Preface

The development of the information society drives the increasing demand for novel optoelectronic materials. Therefore, bismuth-related optoelectronic materials are increasingly favoured due to the unique characteristics of bismuth. This book mainly concentrates on the development of optoelectronic materials for the applications of photon generation, amplification, detection and storage, although there is still a lot of outstanding and innovative research work in this field.

The book contains 8 chapters contributed to by many excellent researchers. It is organized in the following sections:

1.Introduction

**II**

**Section 4**

*by Kuldeep Chand Verma*

Nanoparticles for Photonic Applications

Bismuth Related Data Storage Materials **99**

**Chapter 7 101**

**Chapter 8 131**

Synthesis and Characterization of Multiferroic BiFeO3 for Data Storage

Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties of Bi3+ Doped Manganese Spinel Ferrite

*by V. Jagadeesha Angadi, H.R. Lakshmiprasanna and K. Manjunatha*


Several sections and chapters of the book show how diverse bismuth-related optoelectronic materials are becoming. It is expected that, in the near future, many new bismuth-related optoelectronic materials under development will find important applications in telecommunications, renewable energy, data storage, and so on. All the authors are leading researchers in their respective fields. Their chapters reflect the excellent research work and technology applications of their own work and others. Hence this book, as a new entry to the open access IntechOpen book library, will be useful for researchers, academics, engineers, and students to access expertly summarized specific topics on bismuth-related optoelectronic materials for research, education, and learning purposes.

We would like to take this opportunity to express our great appreciation to all our colleagues and authors as well as collaborators for their support and great contribution to this book. We also would like to thank the IntechOpen editors and staff, especially Mr. Mateo Pulko, Mr. Luka Cvjetkovic, Ms. Marina Dusevic for their excellent support throughout this book project.

> **Yanhua Luo** Photonics and Optical Communications, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, Australia

## **Jianxiang Wen**

Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai University, Shanghai, China

## **Jianzhong Zhang**

**1**

Section 1

Introduction

Key Laboratory of In-Fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin, China

Section 1 Introduction

**3**

e.g. Pb and Bi<sup>+</sup>

, Pb<sup>+</sup>

**Chapter 1**

Materials

**1. Introduction**

Introductory Chapter:

Bismuth-Related Optoelectronic

21st century is the information era. In this rapidly developing information society, more and more optoelectronic materials are needed to meet the increasing demands, including the information generation, transmission, amplification, detection, storage, etc. Among many optoelectronic materials, Bi-related optoelectronic materials are an essential category. The unique properties of bismuth enable the diversity of functions and applications. As schemed in **Figure 1**, bismuth related optoelectronic materials have demonstrated the great potential for the photon generation, amplification, detection and storage. For example, Bi-doped optical fibers (BDFs) have already been proved as the promising active media for the creation of BDF lasers and amplifiers in the near infrared (NIR) region from 1150 to 1800 nm, including the regions of 1250 – 1500 nm and 1600-1800 nm, where efficient rareearth fiber lasers are absent [1]. In addition, Bi/Er and Bi/Er/Yb co-doped optical fiber (BEDF and BEYDF) have further been developed for broader bandwidth [2, 3]. The BDF lasers can cover O, E, S, C, L and U bands, which are commonly used for fiber-optic telecommunication [4, 5]. The optical amplification in O, E, S, C, L and U bands have also been achieved in both BDFs and BEDFs [6–8]. Regarding to the commercialized bismuth-doped fiber amplifier (BDFA), OFS company reported that the BDFA operating over the O-band (1272-1310 nm) extend 425 Gb/s 400GBASE-LR8 transmission beyond 50 km of G.652 fiber [8]. In the detection field, high performance of the broadband photo detecting have been realized in many bismuth related materials, like bismuth selenide nanowire [9], bismuth telluride nanoplate [10], bismuth sulfide nanobelt [11], bismuth nanosheet [12], and bismuth film [13]. In addition, bismuth halide perovskites have been demonstrated as one of the most efficient and promising solar cells for its free of toxic Pb [14]. Bismuth thin film [15], bismuth tellurite [16], bismuth-substituted iron garnet [17], etc. have exhibited great potential for data storage. In addition, both Bi3+ substituted spinel nanoparticles [18]

*Yanhua Luo, Jianxiang Wen and Jianzhong Zhang*

and multiferroic BiFeO3 [19] can be used for the data storage.

The applications of bismuth related optoelectronic materials above are mainly derived from the unique characteristics of bismuth. It is well known that bismuth is a post-transition metal element. Bismuth and its ions have multivalent states ranged from +5 to 0, or even negative valence [20]. Its ions belong to 6p ions, whose valence state is easily changed, particularly under high temperature and reduction atmosphere [21]. Generally, Bi oxides are likely amphoteric (acidic - basic) for lower valence or acidic for higher valence [22]. As Bi82 and Pb83 are located nearby with each other on the periodic table, they have many isoelectronic configurations,

and Bi2+, and Pb2+ and Bi3+. Isoelectronic configurations not

## **Chapter 1**

## Introductory Chapter: Bismuth-Related Optoelectronic Materials

*Yanhua Luo, Jianxiang Wen and Jianzhong Zhang*

## **1. Introduction**

21st century is the information era. In this rapidly developing information society, more and more optoelectronic materials are needed to meet the increasing demands, including the information generation, transmission, amplification, detection, storage, etc. Among many optoelectronic materials, Bi-related optoelectronic materials are an essential category. The unique properties of bismuth enable the diversity of functions and applications. As schemed in **Figure 1**, bismuth related optoelectronic materials have demonstrated the great potential for the photon generation, amplification, detection and storage. For example, Bi-doped optical fibers (BDFs) have already been proved as the promising active media for the creation of BDF lasers and amplifiers in the near infrared (NIR) region from 1150 to 1800 nm, including the regions of 1250 – 1500 nm and 1600-1800 nm, where efficient rareearth fiber lasers are absent [1]. In addition, Bi/Er and Bi/Er/Yb co-doped optical fiber (BEDF and BEYDF) have further been developed for broader bandwidth [2, 3]. The BDF lasers can cover O, E, S, C, L and U bands, which are commonly used for fiber-optic telecommunication [4, 5]. The optical amplification in O, E, S, C, L and U bands have also been achieved in both BDFs and BEDFs [6–8]. Regarding to the commercialized bismuth-doped fiber amplifier (BDFA), OFS company reported that the BDFA operating over the O-band (1272-1310 nm) extend 425 Gb/s 400GBASE-LR8 transmission beyond 50 km of G.652 fiber [8]. In the detection field, high performance of the broadband photo detecting have been realized in many bismuth related materials, like bismuth selenide nanowire [9], bismuth telluride nanoplate [10], bismuth sulfide nanobelt [11], bismuth nanosheet [12], and bismuth film [13]. In addition, bismuth halide perovskites have been demonstrated as one of the most efficient and promising solar cells for its free of toxic Pb [14]. Bismuth thin film [15], bismuth tellurite [16], bismuth-substituted iron garnet [17], etc. have exhibited great potential for data storage. In addition, both Bi3+ substituted spinel nanoparticles [18] and multiferroic BiFeO3 [19] can be used for the data storage.

The applications of bismuth related optoelectronic materials above are mainly derived from the unique characteristics of bismuth. It is well known that bismuth is a post-transition metal element. Bismuth and its ions have multivalent states ranged from +5 to 0, or even negative valence [20]. Its ions belong to 6p ions, whose valence state is easily changed, particularly under high temperature and reduction atmosphere [21]. Generally, Bi oxides are likely amphoteric (acidic - basic) for lower valence or acidic for higher valence [22]. As Bi82 and Pb83 are located nearby with each other on the periodic table, they have many isoelectronic configurations, e.g. Pb and Bi<sup>+</sup> , Pb<sup>+</sup> and Bi2+, and Pb2+ and Bi3+. Isoelectronic configurations not

**Figure 1.** *The functionality of bismuth related optoelectronic materials.*

only allow the replacement of Pb with Bi, but also make their properties similar, including density of their doped borate glasses [23], capability to generate the non-bridging oxygens [24], diamagnetic property [25], the analogy of the photoluminescence [21], etc.

Although there are many reports of bismuth related optoelectronic materials at present, this book mainly focuses on their applications for the photon generation, amplification, detection and storage. The whole book can be structured into three sections:

Section 1: Since the first demonstration of broad NIR luminescence in Bi doped silica glass in 1999 [26], BDF and BEDF has been developed for the full utilization of the huge unused bandwidth of the existing telecommunication network, in response to the forecasted upcoming 'capacity crunch'. In this section, the development of BDF and the post-treatment effect by radiations, like laser, gamma ray and electron beam have been described. Firstly, R. M. D. Alsingery et al. gave an overview of the development of BDFs and their applications in the optical communication system. Then, B. Zhang et al. systematically summarized the photobleaching effect of bismuth active centers (BACs) related to the NIR luminescence in BDF and BEDF, in terms of irradiation intensity/wavelength and temperature. Subsequently, J. Wen et al. fabricated Bi co-doped silica optical fibers with atomic layer deposition (ALD) and modified chemical vapor deposition (MCVD). In addition, gamma radiation effect upon the fluorescence intensity/lifetime, the absorption, as well as Verdet constants of BDFs fabricated have been investigated. Finally, A. Kir'yanov et al. studied effects of electron irradiation on optical properties of bismuth doped phosphosilicate fiber. The results reveal its overall resistance to irradiation in terms of emission and bleaching contrast at excitation into the absorption bands of BACs. In addition, they found a new effect of large dose-dependent Stokes shift, experienced by the fiber's cutoff wavelength due to the radiation induced refractive-index rise in its core area. The studies of these researchers not only give more information about the configuration and structure of BACs, but also offer an effective approach to regulate BACs.

Section 2: In response to the energy crisis, more and more photovoltaic materials are developed. In recent years, the perovskite solar cells were developed with an excellent power conversion efficiency of 25%, which has been considered as one of the most efficient and promising solar cells. To overcome the remaining issues, like

**5**

applications.

*Introductory Chapter: Bismuth-Related Optoelectronic Materials*

end, some strategies for the improved performance are prospected.

The ferroelectricity of BiFeO3 is originated from 6s2

the presence of highly toxic lead and poor stability, bismuth has been introduced to replace Pb in perovskite solar cells due to their similar property. In this section, K. Ahmad overviewed the fabrication of bismuth halide perovskite solar cells. At the

Section 3: In recent years, with the rapid development of optical fiber communication networks, Internet of Things, big data and cloud computing, the amount of global data has shown the exponential growth. The global data volume has already exceeded 45 ZB in 2019, and it is expected to reach 175 ZB in 2025 [27]. To meet the ever-increasing data storage, it is very important to develop the new generation of data storage media for computing performance and the magnetic random access memories storage. In this section, K. C. Verma and J. Angadi described the synthesis and characterization of two bismuth related data storage materials: multiferroic BiFeO3 and Bi3+ doped manganese spinel ferrite nanopar-

Bi3+ and the G-type antiferromagnetic ordering resulted from Fe3+ spins order of cycloidal below Neel temperature. So multiferroic BiFeO3 allows the data to be written electrically and read magnetically due to its magnetoelectric effect observed at room temperature. Especially, the structure of BiFeO3 can be controlled through the selection of appropriate synthesis route, reaction conditions and heating processes. To overcome the drawback of the disappearance of multiferroicity in BiFeO3, several solutions are proposed like the replacement of dopant ions, the control of ions concentration, BiFeO3 composites as well as thin films,

The Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15 and 0.2) nanoparticles were prepared

As the most promising gain medium for the next generation photonic network, the work presented in the Section 1 is evidently not enough. So, challenges and opportunities of the development of BDF and BEDF is further briefed in the following.

Water-free fiber technology has enabled silica optical fibers to achieve ultralow loss transmission over the broad spectral range of 1200-1700 nm, where the transmission loss is less than 0.5 dB/km as shown in **Figure 2** [28]. **Figure 2** also shows the NIR spectral range of some rare earth ions often doped in fibers [28]. It has already demonstrated that the construction of the efficient optical amplifiers based on rare earths doped optical fibers for the extended bands is impossible. Though many researchers have previously been focused on the development of fiber amplifiers and lasers based on fibers doped with rare earth ions, e. g. Er3+, Tm3+, Yb3+, Nd3+, Ho3+, Pr3+, for the extended bands, none of them has demonstrated sufficient optical gain and enough bandwidth for the telecommunication

**2. Challenges and opportunities of bismuth doped optical fiber**

by the solution combustion method and their structural, microstructural and magnetic properties are characterized. Rietveld refined X-ray diffraction (XRD) patterns confirm the single-phase formation with space group Fd3m having spinel cubic structure and the lattice parameters increase with the increase of Bi3+ concentration. The magnetic hysteresis curves reveal the soft magnetic material nature of these nanoparticles, demonstrating the great potential for absorbing electromag-

lone-pair electrons of

*DOI: http://dx.doi.org/10.5772/intechopen.94237*

ticles, respectively.

especially multilayer structures.

netic waves, storage media, etc.

**2.1 Background**

### *Introductory Chapter: Bismuth-Related Optoelectronic Materials DOI: http://dx.doi.org/10.5772/intechopen.94237*

*Bismuth - Fundamentals and Optoelectronic Applications*

*The functionality of bismuth related optoelectronic materials.*

minescence [21], etc.

sections:

**Figure 1.**

only allow the replacement of Pb with Bi, but also make their properties similar, including density of their doped borate glasses [23], capability to generate the non-bridging oxygens [24], diamagnetic property [25], the analogy of the photolu-

Although there are many reports of bismuth related optoelectronic materials at present, this book mainly focuses on their applications for the photon generation, amplification, detection and storage. The whole book can be structured into three

Section 1: Since the first demonstration of broad NIR luminescence in Bi doped silica glass in 1999 [26], BDF and BEDF has been developed for the full utilization of the huge unused bandwidth of the existing telecommunication network, in response to the forecasted upcoming 'capacity crunch'. In this section, the development of BDF and the post-treatment effect by radiations, like laser, gamma ray and electron beam have been described. Firstly, R. M. D. Alsingery et al. gave an overview of the development of BDFs and their applications in the optical communication system. Then, B. Zhang et al. systematically summarized the photobleaching effect of bismuth active centers (BACs) related to the NIR luminescence in BDF and BEDF, in terms of irradiation intensity/wavelength and temperature. Subsequently, J. Wen et al. fabricated Bi co-doped silica optical fibers with atomic layer deposition (ALD) and modified chemical vapor deposition (MCVD). In addition, gamma radiation effect upon the fluorescence intensity/lifetime, the absorption, as well as Verdet constants of BDFs fabricated have been investigated. Finally, A. Kir'yanov et al. studied effects of electron irradiation on optical properties of bismuth doped phosphosilicate fiber. The results reveal its overall resistance to irradiation in terms of emission and bleaching contrast at excitation into the absorption bands of BACs. In addition, they found a new effect of large dose-dependent Stokes shift, experienced by the fiber's cutoff wavelength due to the radiation induced refractive-index rise in its core area. The studies of these researchers not only give more information about the configuration

and structure of BACs, but also offer an effective approach to regulate BACs.

are developed. In recent years, the perovskite solar cells were developed with an excellent power conversion efficiency of 25%, which has been considered as one of the most efficient and promising solar cells. To overcome the remaining issues, like

Section 2: In response to the energy crisis, more and more photovoltaic materials

**4**

the presence of highly toxic lead and poor stability, bismuth has been introduced to replace Pb in perovskite solar cells due to their similar property. In this section, K. Ahmad overviewed the fabrication of bismuth halide perovskite solar cells. At the end, some strategies for the improved performance are prospected.

Section 3: In recent years, with the rapid development of optical fiber communication networks, Internet of Things, big data and cloud computing, the amount of global data has shown the exponential growth. The global data volume has already exceeded 45 ZB in 2019, and it is expected to reach 175 ZB in 2025 [27]. To meet the ever-increasing data storage, it is very important to develop the new generation of data storage media for computing performance and the magnetic random access memories storage. In this section, K. C. Verma and J. Angadi described the synthesis and characterization of two bismuth related data storage materials: multiferroic BiFeO3 and Bi3+ doped manganese spinel ferrite nanoparticles, respectively.

The ferroelectricity of BiFeO3 is originated from 6s2 lone-pair electrons of Bi3+ and the G-type antiferromagnetic ordering resulted from Fe3+ spins order of cycloidal below Neel temperature. So multiferroic BiFeO3 allows the data to be written electrically and read magnetically due to its magnetoelectric effect observed at room temperature. Especially, the structure of BiFeO3 can be controlled through the selection of appropriate synthesis route, reaction conditions and heating processes. To overcome the drawback of the disappearance of multiferroicity in BiFeO3, several solutions are proposed like the replacement of dopant ions, the control of ions concentration, BiFeO3 composites as well as thin films, especially multilayer structures.

The Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15 and 0.2) nanoparticles were prepared by the solution combustion method and their structural, microstructural and magnetic properties are characterized. Rietveld refined X-ray diffraction (XRD) patterns confirm the single-phase formation with space group Fd3m having spinel cubic structure and the lattice parameters increase with the increase of Bi3+ concentration. The magnetic hysteresis curves reveal the soft magnetic material nature of these nanoparticles, demonstrating the great potential for absorbing electromagnetic waves, storage media, etc.

As the most promising gain medium for the next generation photonic network, the work presented in the Section 1 is evidently not enough. So, challenges and opportunities of the development of BDF and BEDF is further briefed in the following.

## **2. Challenges and opportunities of bismuth doped optical fiber**

## **2.1 Background**

Water-free fiber technology has enabled silica optical fibers to achieve ultralow loss transmission over the broad spectral range of 1200-1700 nm, where the transmission loss is less than 0.5 dB/km as shown in **Figure 2** [28]. **Figure 2** also shows the NIR spectral range of some rare earth ions often doped in fibers [28]. It has already demonstrated that the construction of the efficient optical amplifiers based on rare earths doped optical fibers for the extended bands is impossible. Though many researchers have previously been focused on the development of fiber amplifiers and lasers based on fibers doped with rare earth ions, e. g. Er3+, Tm3+, Yb3+, Nd3+, Ho3+, Pr3+, for the extended bands, none of them has demonstrated sufficient optical gain and enough bandwidth for the telecommunication applications.

### **Figure 2.**

*Spectral ranges of various doping elements, normalized emission spectra from each active center interested as well as the low-loss spectrum of silica-based optical fiber.*

Since the first demonstration of broadband NIR luminescence in Bi-doped silica glass [26], many researchers have devoted to the investigation of bismuth doped glasses or materials for the extended band [29–31]. The development in these materials has spurred significant work in optical fiber form [28, 32], since the fabrication of the first BDF in 2005 [33]. Different from the well shielded shell of rare earth ions, the electronic shell of bismuth is easy coupled with the external environment, which finally influences the characteristic properties of BACs. According to the local environments, there exist four types of BACs, which are BAC-Si, BAC-Ge, BAC-P and BAC-Al, relating to SiO2, GeO2, P2O5:SiO2 and Al2O3:SiO2, respectively [5]. The normalized luminescence spectra of these four BACs are plotted in **Figure 2** [34]. Seen from **Figure 2**, BDFs have demonstrated as the promising active media for the NIR region from 1150 to 1800 nm [1]. Especially, through their co-doping, more broader and stronger emission and gain can be achieved, like Bi/Er [7, 35–37], Bi/Tm [38, 39], etc. [40, 41].

#### **2.2 Remaining challenges**

Despite the great success in the development of the BDF technology for the unused bandwidth, there remain many fundamental scientific and technological issues and challenges, before these fiber lasers and amplifiers can be practically and commercially used.

*On the scientific side:* The main challenge is that the nature of bismuth NIR emitting centers is still not clear [1]. Difficulties mainly arise from Bi where its *d* orbitals are easily coupled to the surrounding environment. But it is such coupling, which allows the formation of broadband NIR emission center through the tailoring of the external environment by additional dopants such as Ge, P, Al, etc. Meanwhile, bismuth as the wonder metal, can proceed reduction reactions with no other element and produce such a variety of products [42]. Especially, under the high temperature, the change of the valent state of bismuth in Bi-doped glasses occurs [43]: Bi3+ → Bi2+ → Bi+ → Bi/Bi2, Bi2 − , Bi3, etc. → (Bi)n, where Bi2, Bi2 − , Bi3, etc. are Bi clusters and (Bi)n is metallic colloid. As bismuth doped glasses and fibers often undergo the high temperature in the fabrication process. For example, under the high temperature treatment, the color of the doped core in the BEDF preform is clearly changed as indicated in **Figure 3** (the dark color is often taken as the evidence of the formation of (Bi)n). So many types of bismuth often co-exist in these Bi doped glasses and fibers. Their properties, like unpaired electrons, radius and fluorescence lifetime are different with each other as listed in **Table 1**.

**7**

*Introductory Chapter: Bismuth-Related Optoelectronic Materials*

So far, a number of hypotheses are reported about the origin of the NIR emis-

*Thermal treatment influence upon the fiber core in the BEDF preform: (a) annealing conditions; (b) the color* 

**electrons [44]**

Bi3+ [Xe]5d106s2 0 0.96 — 1 Bi4+ [Xe]5d106s1 1 — — — Bi5+ [Xe]5d10 0 0.74 — — Bi6+ [Xe]5d9 1 — — — BiO — — 1.70 ≥102 ≥10

defects and others, but none of them have been directly confirmed [1]. Though the recent report by Dianov et al. has confirmed that Bi-related NIR emitting centers are clusters consisting of Bi ions and oxygen deficiency centers instead of Bi ions themselves [1], the exact form of bismuth in BAC remains unclear. In addition, the NIR luminescence has also been observed from Bi-doped CsI halide crystals [47], fluoride glasses [48], etc. where no oxygen deficiency will exist in these materials. Therefore, to conquer this challenge, further research is necessary to get reliable results on the nature of Bi-related NIR emitting centers in Bi-doped glasses and optical fibers of various compositions and fabrication techniques with different

*On the technological side:* As the valence state of Bi in BDF/BEDF will change during the fabrication process, so it becomes a technical challenge to control the formation rate of BAC for the preparation of optical fibers. Both the valence state of bismuth and oxygen deficiency centers are sensitive to the processing temperature [43, 49]. In addition, bismuth oxide is easier evaporated during the collapsing process of preform fabrication with the MCVD technique compared with rare earth oxide. Hence, the control of the valence state of Bi as well as the formation rate of BAC is hardly achieved in BDF/BEDF. So there often co-exist many types of Bi ions or BAC in Bi-doped materials [50]. Though the full control of the formation of

, Bi5+, Bi−

<sup>−</sup> — — — ≥102 ~10

clusters, BiO, Bi2

**Radius [Å] [45]**

6p3 3 1.56 ≥102 ~10

6p2 2 1.45 ~102 ≥10

6p1 1 1.16 — ~10

− , Bi2

2− point

**Lifetime [**μ**s] [46]**

**NIR Visi**

*DOI: http://dx.doi.org/10.5772/intechopen.94237*

*change in the core part with thermal treatment.*

Bi0+ [Xe]5d106s2

Bi1+ [Xe]5d106s2

Bi2+ [Xe]5d106s2

**Valence Configuration Number of unpair** 

**Figure 3.**

Bi2

**Table 1.**

sion center in Bi-doped glasses, like: Bi+

*Upaired electrons, radius and fluorescence lifetime of bismuth ions.*

processing conditions.

*Introductory Chapter: Bismuth-Related Optoelectronic Materials DOI: http://dx.doi.org/10.5772/intechopen.94237*

#### **Figure 3.**

*Bismuth - Fundamentals and Optoelectronic Applications*

[7, 35–37], Bi/Tm [38, 39], etc. [40, 41].

*well as the low-loss spectrum of silica-based optical fiber.*

occurs [43]: Bi3+ → Bi2+ → Bi+ → Bi/Bi2, Bi2

**2.2 Remaining challenges**

commercially used.

**Figure 2.**

Since the first demonstration of broadband NIR luminescence in Bi-doped silica glass [26], many researchers have devoted to the investigation of bismuth doped glasses or materials for the extended band [29–31]. The development in these materials has spurred significant work in optical fiber form [28, 32], since the fabrication of the first BDF in 2005 [33]. Different from the well shielded shell of rare earth ions, the electronic shell of bismuth is easy coupled with the external environment, which finally influences the characteristic properties of BACs. According to the local environments, there exist four types of BACs, which are BAC-Si, BAC-Ge, BAC-P and BAC-Al, relating to SiO2, GeO2, P2O5:SiO2 and Al2O3:SiO2, respectively [5]. The normalized luminescence spectra of these four BACs are plotted in **Figure 2** [34]. Seen from **Figure 2**, BDFs have demonstrated as the promising active media for the NIR region from 1150 to 1800 nm [1]. Especially, through their co-doping, more broader and stronger emission and gain can be achieved, like Bi/Er

*Spectral ranges of various doping elements, normalized emission spectra from each active center interested as* 

Despite the great success in the development of the BDF technology for the unused bandwidth, there remain many fundamental scientific and technological issues and challenges, before these fiber lasers and amplifiers can be practically and

*On the scientific side:* The main challenge is that the nature of bismuth NIR emitting centers is still not clear [1]. Difficulties mainly arise from Bi where its *d* orbitals are easily coupled to the surrounding environment. But it is such coupling, which allows the formation of broadband NIR emission center through the tailoring of the external environment by additional dopants such as Ge, P, Al, etc. Meanwhile, bismuth as the wonder metal, can proceed reduction reactions with no other element and produce such a variety of products [42]. Especially, under the high temperature, the change of the valent state of bismuth in Bi-doped glasses

−

etc. are Bi clusters and (Bi)n is metallic colloid. As bismuth doped glasses and fibers often undergo the high temperature in the fabrication process. For example, under the high temperature treatment, the color of the doped core in the BEDF preform is clearly changed as indicated in **Figure 3** (the dark color is often taken as the evidence of the formation of (Bi)n). So many types of bismuth often co-exist in these Bi doped glasses and fibers. Their properties, like unpaired electrons, radius and

fluorescence lifetime are different with each other as listed in **Table 1**.

, Bi3, etc. → (Bi)n, where Bi2, Bi2

− , Bi3,

**6**

*Thermal treatment influence upon the fiber core in the BEDF preform: (a) annealing conditions; (b) the color change in the core part with thermal treatment.*


#### **Table 1.**

*Upaired electrons, radius and fluorescence lifetime of bismuth ions.*

So far, a number of hypotheses are reported about the origin of the NIR emission center in Bi-doped glasses, like: Bi+ , Bi5+, Bi− clusters, BiO, Bi2 − , Bi2 2− point defects and others, but none of them have been directly confirmed [1]. Though the recent report by Dianov et al. has confirmed that Bi-related NIR emitting centers are clusters consisting of Bi ions and oxygen deficiency centers instead of Bi ions themselves [1], the exact form of bismuth in BAC remains unclear. In addition, the NIR luminescence has also been observed from Bi-doped CsI halide crystals [47], fluoride glasses [48], etc. where no oxygen deficiency will exist in these materials. Therefore, to conquer this challenge, further research is necessary to get reliable results on the nature of Bi-related NIR emitting centers in Bi-doped glasses and optical fibers of various compositions and fabrication techniques with different processing conditions.

*On the technological side:* As the valence state of Bi in BDF/BEDF will change during the fabrication process, so it becomes a technical challenge to control the formation rate of BAC for the preparation of optical fibers. Both the valence state of bismuth and oxygen deficiency centers are sensitive to the processing temperature [43, 49]. In addition, bismuth oxide is easier evaporated during the collapsing process of preform fabrication with the MCVD technique compared with rare earth oxide. Hence, the control of the valence state of Bi as well as the formation rate of BAC is hardly achieved in BDF/BEDF. So there often co-exist many types of Bi ions or BAC in Bi-doped materials [50]. Though the full control of the formation of

BACs is very hard, reductive agents, like high-purity silicon powder or sucrose in MCVD process [51] and SiC in melt and pour glass [52] have already been introduced in the fabrication of the Bi-doped materials as bismuth NIR emitting centers are formed in an endothermic redox chemical reaction [53]. In addition, post treatments, like femtosecond laser [54], thermal treatment [55, 56], γ-radiation [57], H2 reduction [58], etc. have also been tried to activate and control the BAC. Recently, M. Melkumov et al. have tried to improve the performance of BDF by the optimization of drawing and MCVD processing conditions [59, 60]. Though these solutions can regulate the formation of BAC to some degree, the success rate still cannot be quantified due to the unclear structure of the BAC. In addition, most of BDFs with lasing and amplification are doped with very low content of bismuth (usually <0.1 wt.%) [5], which is often lower than the detection limit of mostly used equipment-energy-dispersive X-ray (EDX) analyzer. However, the performance improvement by the increment of Bi concentration is limited by the fast growth of the background loss in fiber [5]. So the concentration increment and the control growth of the background loss should be balanced for high performance BDF and BEDF. All these technical issues are subject to further in-depth and systematic research and development, such as the selection of dopants and their compositions, and fabrication conditions, etc.

## **Author details**

Yanhua Luo1 \*, Jianxiang Wen<sup>2</sup> and Jianzhong Zhang3

1 Photonics and Optical Communications, School of Electrical Engineering, University of New South Wales, Sydney 2052, NSW, Australia

2 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China

3 Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, School of Science, Harbin Engineering University, Harbin 150001, China

\*Address all correspondence to: yanhua.luo1@unsw.edu.au

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**9**

2017

*Introductory Chapter: Bismuth-Related Optoelectronic Materials*

Firstov SV et al., Simple broadband bismuth doped fiber amplifier (BDFA)

to extend O-band transmission reach and capacity, in Optical Fiber Communication Conference (OFC) 2019, San Diego, California, 2019: Optical Society of America, p. M1J.4

[9] Sharma A, Bhattacharyya B, Srivastava AK, Senguttuvan TD, and Husale S, High performance broadband

photodetector using fabricated nanowires of bismuth selenide, Scientific Reports, **6**(1), 19138, 2016

**2**(3), 1333-1339, 2020

[12] Huang H, Ren X, Li Z,

2020

2018

2018

**5**(1), 12320, 2015

[10] Zhang Y, You Q, Huang W, Hu L, Ju J, Ge Y et al. Few-layer hexagonal bismuth telluride (Bi2Te3) nanoplates with high-performance UV-Vis photodetection, Nanoscale Advances,

[11] Xu J, Li H, Jiang K, Yao H, Fang F, Chen F et al., Synthesis of bismuth sulfide nanobelts for high performance broadband photodetectors, Journal of Materials Chemistry C, **8**(6), 2102-2108,

Wang H, Huang Z, Qiao H et al., Twodimensional bismuth nanosheets as prospective photo-detector with tunable optoelectronic performance, Nanotechnology, **29**(23), 235201,

[13] Yao JD, Shao JM, and Yang GW, Ultra-broadband and high-responsive photodetectors based on bismuth film at room temperature, Scientific Reports,

[14] Ahmad K, Ansari S.N, Natarajan K, and Mobin SM, Design and synthesis

[(CH3NH3)3Bi2Cl9]n perovskite: a new light absorber material for lead free perovskite solar cells, ACS Applied Energy Materials, **1**(6), 2405-2409,

of 1D-polymeric chain based

*DOI: http://dx.doi.org/10.5772/intechopen.94237*

[2] Luo Y, Wen J, Zhang J, Canning J, and Peng G-D, Bismuth and erbium codoped optical fiber with ultrabroadband luminescence across O-, E-, S-, C-, and L-bands, Optics Letters, **37**(16), 3447-

[3] Sathi ZM, Zhang J, Luo Y, Canning J, and Peng GD, Improving broadband emission within Bi/Er doped silicate fibres with Yb co-doping, Optical Materials Express, **5**(10), 2096-2105,

[4] Firstov S, Alyshev S, Melkumov M, Riumkin K, Shubin A, and Dianov E, Bismuth-doped optical fibers and fiber lasers for a spectral region of 1600- 1800 nm, Optics Letters, **39**(24),

[5] Bufetov IA, Melkumov MA, Firstov S V, Riumkin KE, Shubin AV, Khopin VF et al., "Bi-doped optical fibers and fiber lasers," IEEE Journal of Selected Topics in Quantum Electronics, **20**(5),

[6] Dvoyrin VV, Medvedkov OI,

**16**(21), 16971-16976, 2008

[7] Firstov SV, Firstov SV,

Mashinsky VM, Umnikov AA, Guryanov AN, and Dianov EM, "Optical amplification in 1430-1495 nm range and laser action in Bi-doped fibers," Optics Express,

Riumkin KE, Khegai AM, Alyshev SV, Melkumov MA, Khopin VF et al., Wideband bismuth- and erbiumcodoped optical fiber amplifier for C+L+U-telecommunication band, Laser Physics Letters, **14**(11), 110001,

[8] Mikhailov V, Melkumov MA, Inniss D, Khegai AM, Riumkin KE,

[1] Dianov EM, Nature of Bi-related near IR active centers in glasses: state of the art and first reliable results, Laser Physics Letters, **12**(9), 095106, 2015

**References**

3449, 2012

2015

6927-6930, 2014

0903815, 2014

*Introductory Chapter: Bismuth-Related Optoelectronic Materials DOI: http://dx.doi.org/10.5772/intechopen.94237*

## **References**

*Bismuth - Fundamentals and Optoelectronic Applications*

BACs is very hard, reductive agents, like high-purity silicon powder or sucrose in MCVD process [51] and SiC in melt and pour glass [52] have already been introduced in the fabrication of the Bi-doped materials as bismuth NIR emitting centers are formed in an endothermic redox chemical reaction [53]. In addition, post treatments, like femtosecond laser [54], thermal treatment [55, 56], γ-radiation [57], H2 reduction [58], etc. have also been tried to activate and control the BAC. Recently, M. Melkumov et al. have tried to improve the performance of BDF by the optimization of drawing and MCVD processing conditions [59, 60]. Though these solutions can regulate the formation of BAC to some degree, the success rate still cannot be quantified due to the unclear structure of the BAC. In addition, most of BDFs with lasing and amplification are doped with very low content of bismuth (usually <0.1 wt.%) [5], which is often lower than the detection limit of mostly used equipment-energy-dispersive X-ray (EDX) analyzer. However, the performance improvement by the increment of Bi concentration is limited by the fast growth of the background loss in fiber [5]. So the concentration increment and the control growth of the background loss should be balanced for high performance BDF and BEDF. All these technical issues are subject to further in-depth and systematic research and development, such as the selection of dopants and their compositions,

**8**

**Author details**

\*, Jianxiang Wen<sup>2</sup>

provided the original work is properly cited.

and fabrication conditions, etc.

and Jianzhong Zhang3

1 Photonics and Optical Communications, School of Electrical Engineering,

2 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data

3 Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, School of

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

University of New South Wales, Sydney 2052, NSW, Australia

Science, Harbin Engineering University, Harbin 150001, China

\*Address all correspondence to: yanhua.luo1@unsw.edu.au

Science, Shanghai University, Shanghai 200444, China

Yanhua Luo1

[1] Dianov EM, Nature of Bi-related near IR active centers in glasses: state of the art and first reliable results, Laser Physics Letters, **12**(9), 095106, 2015

[2] Luo Y, Wen J, Zhang J, Canning J, and Peng G-D, Bismuth and erbium codoped optical fiber with ultrabroadband luminescence across O-, E-, S-, C-, and L-bands, Optics Letters, **37**(16), 3447- 3449, 2012

[3] Sathi ZM, Zhang J, Luo Y, Canning J, and Peng GD, Improving broadband emission within Bi/Er doped silicate fibres with Yb co-doping, Optical Materials Express, **5**(10), 2096-2105, 2015

[4] Firstov S, Alyshev S, Melkumov M, Riumkin K, Shubin A, and Dianov E, Bismuth-doped optical fibers and fiber lasers for a spectral region of 1600- 1800 nm, Optics Letters, **39**(24), 6927-6930, 2014

[5] Bufetov IA, Melkumov MA, Firstov S V, Riumkin KE, Shubin AV, Khopin VF et al., "Bi-doped optical fibers and fiber lasers," IEEE Journal of Selected Topics in Quantum Electronics, **20**(5), 0903815, 2014

[6] Dvoyrin VV, Medvedkov OI, Mashinsky VM, Umnikov AA, Guryanov AN, and Dianov EM, "Optical amplification in 1430-1495 nm range and laser action in Bi-doped fibers," Optics Express, **16**(21), 16971-16976, 2008

[7] Firstov SV, Firstov SV, Riumkin KE, Khegai AM, Alyshev SV, Melkumov MA, Khopin VF et al., Wideband bismuth- and erbiumcodoped optical fiber amplifier for C+L+U-telecommunication band, Laser Physics Letters, **14**(11), 110001, 2017

[8] Mikhailov V, Melkumov MA, Inniss D, Khegai AM, Riumkin KE, Firstov SV et al., Simple broadband bismuth doped fiber amplifier (BDFA) to extend O-band transmission reach and capacity, in Optical Fiber Communication Conference (OFC) 2019, San Diego, California, 2019: Optical Society of America, p. M1J.4

[9] Sharma A, Bhattacharyya B, Srivastava AK, Senguttuvan TD, and Husale S, High performance broadband photodetector using fabricated nanowires of bismuth selenide, Scientific Reports, **6**(1), 19138, 2016

[10] Zhang Y, You Q, Huang W, Hu L, Ju J, Ge Y et al. Few-layer hexagonal bismuth telluride (Bi2Te3) nanoplates with high-performance UV-Vis photodetection, Nanoscale Advances, **2**(3), 1333-1339, 2020

[11] Xu J, Li H, Jiang K, Yao H, Fang F, Chen F et al., Synthesis of bismuth sulfide nanobelts for high performance broadband photodetectors, Journal of Materials Chemistry C, **8**(6), 2102-2108, 2020

[12] Huang H, Ren X, Li Z, Wang H, Huang Z, Qiao H et al., Twodimensional bismuth nanosheets as prospective photo-detector with tunable optoelectronic performance, Nanotechnology, **29**(23), 235201, 2018

[13] Yao JD, Shao JM, and Yang GW, Ultra-broadband and high-responsive photodetectors based on bismuth film at room temperature, Scientific Reports, **5**(1), 12320, 2015

[14] Ahmad K, Ansari S.N, Natarajan K, and Mobin SM, Design and synthesis of 1D-polymeric chain based [(CH3NH3)3Bi2Cl9]n perovskite: a new light absorber material for lead free perovskite solar cells, ACS Applied Energy Materials, **1**(6), 2405-2409, 2018

[15] Suh S and Craighead H, Optical writing characteristics of multilayered bismuth/selenium thin films, Optical Engineering, **26**(6), 266524, 1987

[16] Oliveira ID, Carvalho JF, Fabris ZV, and Frejlich J, Holographic recording and characterization of photorefractive Bi2TeO5 crystals at 633nm wavelength light, Journal of Applied Physics, **115**(16), 163514, 2014

[17] Anoikin EV and Sides PJ, "Plasmaactivated chemical vapor deposition of bismuth-substituted iron garnets for magneto-optical data storage," IEEE Transactions on Magnetics, **31**(6), 3239- 3241, 1995

[18] Seevakan K, Manikandan A, Devendran P, Slimani Y, Baykal A, and Alagesan T, Structural, magnetic and electrochemical characterizations of Bi2Mo2O9 nanoparticle for supercapacitor application, Journal of Magnetism and Magnetic Materials, **486**, 165254, 2019

[19] Wang J, Neaton JB, Zheng H, Nagarajan V, Ogale SB, Liu B et al., Epitaxial BiFeO3 multiferroic thin film heterostructures, Science, **299**(5613), 1719-1722, 2003

[20] Xu L, Bobev S, El-Bahraoui J, and Sevov SC, A naked diatomic molecule of bismuth, [Bi2] 2−, with a short Bi−Bi bond: synthesis and structure, Journal of the American Chemical Society, **122**(8), 1838-1839, 2000

[21] Hughes MA, Gwilliam RM, Homewood K, Gholipour B, Hewak DW, Lee T-H et al., On the analogy between photoluminescence and carrier-type reversal in Bi- and Pb-doped glasses, Optics Express, **21**(7), 8101-8115, 2013

[22] http://ww2.chemistry.gatech. edu/~barefield/1311/coordination\_ complexes.pdf (accessed 20/09/2020) [23] Khanisanij M and Sidek HAA, Elastic behavior of borate glasses containing lead and bismuth oxides, Advances in Materials Science and Engineering, **2014**, 452830, 2014

[24] Sidek HAA,

Hamezan M, Zaidan AW, Talib ZA, and Kaida K, Optical characterization of lead-bismuth phosphate glasses, American Journal of Applied Sciences, **2**(8), 1266-1269, 2005.

[25] Elisa M, Iordanescu R, Vasiliu C, Sava BA, Boroica L, Valeanu M, Kuncse V et al., Magnetic and magneto-optical properties of Bi and Pb-containing aluminophosphate glass, Journal of Non-Crystalline Solids, **465**, 55-58, 2017

[26] Murata K, Fujimoto Y, Kanabe T, Fujita H, and Nakatsuka M, Bi-doped SiO2 as a new laser material for an intense laser, Fusion Engineering and Design, **44**(1), 437-439, 1999

[27] Reinsel D, Gantz J, and Rydning J, "The digitization of the world from edge to core," IDC, 2018.

[28] Dianov EM, Amplification in extended transmission bands using bismuth-doped optical fibers, Journal of Lightwave Technology, **31**(4), 681-688, 2013

[29] Fujimoto Y and Nakatsuka M, Infrared luminescence from bismuthdoped silica glass, Japanese Journal of Applied Physics, **49**(2001), L279-L281, 2001

[30] Meng X, Qiu J, Peng M, Chen D, Zhao Q, Jiang X et al., Near infrared broadband emission of bismuthdoped aluminophosphate glass, Optics Express, **13**, 1628-1634, 2005

[31] Sun H-T, Zhou J, and Qiu J, Recent advances in bismuth activated photonic materials, Progress in Materials Science, **64**, 1-72, 2014

**11**

*Introductory Chapter: Bismuth-Related Optoelectronic Materials*

emission in Tm-Bi codoped sodiumgermanium-gallate glasses, Optics Express, **19**(7), 6514-6523, 2011

[40] Ruan J, Chi Y, Liu X, Dong G, Lin G, Chen D et al., Enhanced nearinfrared emission and broadband optical amplification in Yb–Bi co-doped germanosilicate glasses, Journal of Physics D: Applied Physics, **42**(15),

[41] Zhang P, Chen N, Wang R, Huang X, Zhu S, Li Z et al., Charge compensation effects of Yb3+ on the Bi+

near-infrared emission in PbF2 crystal, Optics Letters, **43**(10), 2372-2375, 2018

[42] Corbett JD, Homopolyatomic ions of the post-transition elements synthesis, structure and bonding (Progress in Inorganic Chemistry). New

[43] Khonthon S, Morimoto S, Arai Y, and Ohishi Y, Redox equilibrium and NIR luminescence of Bi2O3-containing glasses, Optical Materials, **31**(8), 1262-

Nakatsuka M, and Young-Seok S, Local structures of bismuth ion in bismuthdoped silica glasses analyzed using Bi LIII X-ray absorption fine structure, Journal of the American Ceramic Society, **90**(11), 3596-3600, 2007

[45] Sun H-T, Matsushita Y, Sakka Y, Shirahata N, Tanaka M, Katsuya Y et al., Synchrotron X-ray, photoluminescence, and quantum chemistry studies of bismuth-embedded dehydrated zeolite Y, Journal of the American Chemical Society, **134**(6), 2918-2921, 2012

[46] Sokolov VO, Plotnichenko VG, and Dianov EM, The origin of near-IR luminescence in bismuth-doped silica and germania glasses free of other dopants: First-principle study, Optical Materals Express, **3**(8), 1059-1074, 2013

[44] Ohkura T, Fujimoto Y,

:

155102, 2009

York: Wiley, 1976

1268, 2009

*DOI: http://dx.doi.org/10.5772/intechopen.94237*

[32] Dianov EM, Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media, Quantum Electronics,

[33] Dvoyrin VV, Mashinsky VM, Dianov EM, Umnikov AA, Yashkov MV, and Guranov AN, Absorption, fluorescence and optical amplification in MCVD Bismuth-doped silica glass optical fibres, ECOC Proceeding, **4**, 949-950,

[34] Dianov EM, Firstov SV, and

[35] Kuwada Y, Fujimoto Y, and Nakatsuka M, Ultrawideband light emission from bismuth and erbium doped silica, Japanese Journal of Applied Physics, **46**, 1531-1532 2007

[36] Peng M, Zhang N, Wondraczek L, Qiu J, Yang Z, and Zhang Q, Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses, Optics Express, **19**(21), 20799-

Melkumov M A, Bismuth-doped optical fibers: advances and bew developments, in Workshop on Specialty Optical Fibers and Their Applications, Hong Kong, 2015: Optical Society of America, in OSA Technical Digest (online), p.

**42**(9), 754 – 761, 2012

2005

WT1A.4

20807, 2011

[37] Luo Y, Wen J, Zhang J,

**37**(16), 3447-3449, 2012

glasses for broadband optical

2486-2488, 2009

Canning J, and Peng G-D, Bismuth and erbium codoped optical fiber with ultrabroadband luminescence across O-, E-, S-, C-, and L-bands, Optics Letters,

[38] Ruan J, Dong G, Liu X, Zhang Q, Chen D, and Qiu J, Enhanced broadband near-infrared emission and energy transfer in Bi–Tm-codoped germanate

amplification, Optics Letters, **34**(16),

[39] Zhou B, Lin H, Chen B, and Pun EY-B, Superbroadband near-infrared *Introductory Chapter: Bismuth-Related Optoelectronic Materials DOI: http://dx.doi.org/10.5772/intechopen.94237*

[32] Dianov EM, Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media, Quantum Electronics, **42**(9), 754 – 761, 2012

*Bismuth - Fundamentals and Optoelectronic Applications*

[23] Khanisanij M and Sidek HAA, Elastic behavior of borate glasses containing lead and bismuth oxides, Advances in Materials Science and Engineering, **2014**, 452830, 2014

Hamezan M, Zaidan AW, Talib ZA, and Kaida K, Optical characterization of lead-bismuth phosphate glasses, American Journal of Applied Sciences,

[25] Elisa M, Iordanescu R, Vasiliu C, Sava BA, Boroica L, Valeanu M, Kuncse V et al., Magnetic and magneto-optical properties of Bi and Pb-containing aluminophosphate glass, Journal of Non-Crystalline Solids, **465**, 55-58, 2017

[26] Murata K, Fujimoto Y, Kanabe T, Fujita H, and Nakatsuka M, Bi-doped SiO2 as a new laser material for an intense laser, Fusion Engineering and

[27] Reinsel D, Gantz J, and Rydning J, "The digitization of the world from edge

[28] Dianov EM, Amplification in extended transmission bands using bismuth-doped optical fibers, Journal of Lightwave Technology, **31**(4), 681-688,

[29] Fujimoto Y and Nakatsuka M, Infrared luminescence from bismuthdoped silica glass, Japanese Journal of Applied Physics, **49**(2001), L279-L281,

[30] Meng X, Qiu J, Peng M, Chen D, Zhao Q, Jiang X et al., Near infrared broadband emission of bismuthdoped aluminophosphate glass, Optics

[31] Sun H-T, Zhou J, and Qiu J, Recent advances in bismuth activated photonic materials, Progress in Materials Science,

Express, **13**, 1628-1634, 2005

**64**, 1-72, 2014

Design, **44**(1), 437-439, 1999

to core," IDC, 2018.

2013

2001

[24] Sidek HAA,

**2**(8), 1266-1269, 2005.

[15] Suh S and Craighead H, Optical writing characteristics of multilayered bismuth/selenium thin films, Optical Engineering, **26**(6), 266524, 1987

[16] Oliveira ID, Carvalho JF, Fabris ZV, and Frejlich J, Holographic recording and characterization of photorefractive Bi2TeO5 crystals at 633nm wavelength light, Journal of Applied Physics,

[17] Anoikin EV and Sides PJ, "Plasmaactivated chemical vapor deposition of bismuth-substituted iron garnets for magneto-optical data storage," IEEE Transactions on Magnetics, **31**(6), 3239-

[18] Seevakan K, Manikandan A, Devendran P, Slimani Y, Baykal A, and Alagesan T, Structural, magnetic and electrochemical characterizations

of Bi2Mo2O9 nanoparticle for

**486**, 165254, 2019

1719-1722, 2003

of bismuth, [Bi2]

**122**(8), 1838-1839, 2000

[21] Hughes MA, Gwilliam RM,

[22] http://ww2.chemistry.gatech. edu/~barefield/1311/coordination\_ complexes.pdf (accessed 20/09/2020)

supercapacitor application, Journal of Magnetism and Magnetic Materials,

[19] Wang J, Neaton JB, Zheng H, Nagarajan V, Ogale SB, Liu B et al., Epitaxial BiFeO3 multiferroic thin film heterostructures, Science, **299**(5613),

[20] Xu L, Bobev S, El-Bahraoui J, and Sevov SC, A naked diatomic molecule

bond: synthesis and structure, Journal of the American Chemical Society,

Homewood K, Gholipour B, Hewak DW, Lee T-H et al., On the analogy between photoluminescence and carrier-type reversal in Bi- and Pb-doped glasses, Optics Express, **21**(7), 8101-8115,

2−, with a short Bi−Bi

**115**(16), 163514, 2014

3241, 1995

**10**

2013

[33] Dvoyrin VV, Mashinsky VM, Dianov EM, Umnikov AA, Yashkov MV, and Guranov AN, Absorption, fluorescence and optical amplification in MCVD Bismuth-doped silica glass optical fibres, ECOC Proceeding, **4**, 949-950, 2005

[34] Dianov EM, Firstov SV, and Melkumov M A, Bismuth-doped optical fibers: advances and bew developments, in Workshop on Specialty Optical Fibers and Their Applications, Hong Kong, 2015: Optical Society of America, in OSA Technical Digest (online), p. WT1A.4

[35] Kuwada Y, Fujimoto Y, and Nakatsuka M, Ultrawideband light emission from bismuth and erbium doped silica, Japanese Journal of Applied Physics, **46**, 1531-1532 2007

[36] Peng M, Zhang N, Wondraczek L, Qiu J, Yang Z, and Zhang Q, Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses, Optics Express, **19**(21), 20799- 20807, 2011

[37] Luo Y, Wen J, Zhang J, Canning J, and Peng G-D, Bismuth and erbium codoped optical fiber with ultrabroadband luminescence across O-, E-, S-, C-, and L-bands, Optics Letters, **37**(16), 3447-3449, 2012

[38] Ruan J, Dong G, Liu X, Zhang Q, Chen D, and Qiu J, Enhanced broadband near-infrared emission and energy transfer in Bi–Tm-codoped germanate glasses for broadband optical amplification, Optics Letters, **34**(16), 2486-2488, 2009

[39] Zhou B, Lin H, Chen B, and Pun EY-B, Superbroadband near-infrared emission in Tm-Bi codoped sodiumgermanium-gallate glasses, Optics Express, **19**(7), 6514-6523, 2011

[40] Ruan J, Chi Y, Liu X, Dong G, Lin G, Chen D et al., Enhanced nearinfrared emission and broadband optical amplification in Yb–Bi co-doped germanosilicate glasses, Journal of Physics D: Applied Physics, **42**(15), 155102, 2009

[41] Zhang P, Chen N, Wang R, Huang X, Zhu S, Li Z et al., Charge compensation effects of Yb3+ on the Bi+ : near-infrared emission in PbF2 crystal, Optics Letters, **43**(10), 2372-2375, 2018

[42] Corbett JD, Homopolyatomic ions of the post-transition elements synthesis, structure and bonding (Progress in Inorganic Chemistry). New York: Wiley, 1976

[43] Khonthon S, Morimoto S, Arai Y, and Ohishi Y, Redox equilibrium and NIR luminescence of Bi2O3-containing glasses, Optical Materials, **31**(8), 1262- 1268, 2009

[44] Ohkura T, Fujimoto Y, Nakatsuka M, and Young-Seok S, Local structures of bismuth ion in bismuthdoped silica glasses analyzed using Bi LIII X-ray absorption fine structure, Journal of the American Ceramic Society, **90**(11), 3596-3600, 2007

[45] Sun H-T, Matsushita Y, Sakka Y, Shirahata N, Tanaka M, Katsuya Y et al., Synchrotron X-ray, photoluminescence, and quantum chemistry studies of bismuth-embedded dehydrated zeolite Y, Journal of the American Chemical Society, **134**(6), 2918-2921, 2012

[46] Sokolov VO, Plotnichenko VG, and Dianov EM, The origin of near-IR luminescence in bismuth-doped silica and germania glasses free of other dopants: First-principle study, Optical Materals Express, **3**(8), 1059-1074, 2013 [47] Su L, Zhao H, Li H, Zheng L, Ren G, Xu J et al., Near-infrared ultrabroadband luminescence spectra properties of subvalent bismuth in CsI halide crystals, Optics Letters, **36**(23), 4551-4553, 2011

[48] Romanov AN, Haula EV, Fattakhova ZT, Veber AA, Tsvetkov VB, Zhigunov DM et al., Near-IR luminescence from subvalent bismuth species in fluoride glass, Optical Materials, **34**(1), 155-158, 2011

[49] Hanafusa H, Hibino Y, and Yamamoto F, Formation mechanism of drawing-induced defects in optical fibers, Journal of Non-Crystalline Solids, **95-96**, 655-661, 1987

[50] Xu W, Peng M, Ma Z, Dong G, and Qiu J, A new study on bismuth doped oxide glasses, Optics Express, **20**(14), 15692-15702, 2012

[51] Li J, Jiang Z, Peng J, Dai N, Li H, Yang L et al. Preparation method of bismuth-doped silica fiber controllable in components and valence state, and bismuth-doped silica fiber, China Patent, CN103601364A, 2020

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[53] Veber A, Cicconi MR, Puri A, and de Ligny D, Optical properties and bismuth redox in Bi-doped high-silica Al–Si glasses, The Journal of Physical Chemistry C, **122**(34), 19777-19792, 2018

[54] Kononenko V, Pashinin V, Galagan B, Sverchkov S, Denker B, Konov V, et al., Laser induced rise of luminescence efficiency in Bi-doped glass, Physics Procedia, **12**, 156-163, 2011

[55] Wei S, Luo Y, Fan D, Xiao G, Chu Y, Zhang B et al., BAC activation by thermal quenching in bismuth/erbium codoped fiber, Optics Letters, 44(7), 1872-1875, 2019

[56] Kharakhordin AV, Alyshev SV, Firstova EG, Lobanov AS, Khopin VF, Khegai AM et al., Lasing properties of thermally treated GeO2-SiO2 glass fibers doped with bismuth," Applied Physics B, **126**(5), 87, 2020

[57] D. Sporea, Mihai L, Neguţ D, Luo Y, Yan B, Ding M et al., γ irradiation induced effects on bismuth active centres and related photoluminescence properties of Bi/Er co-doped optical fibres, Scientific Reports, **6**(1), 29827, 2016

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[59] S. Firstov, Levchenko A, Kharakhordin A, Khegai A, Alyshev S, Melkumov M et al., Effect of drawing conditions on optical properties of bismuth-doped high-GeO2–SiO2 fibers, IEEE Photonics Technology Letters, **32**(15), 913-916, 2020

[60] Khegai A, Afanasiev F, Ososkov Y, Riumkin K, Khopin V, Lobanov A et al., The influence of the MCVD process parameters on the optical properties of bismuth-doped phosphosilicate fibers, Journal of Lightwave Technology, doi: 10.1109/JLT.2020.3008536, 2020

**13**

Section 2

Bismuth Optical Fibers

Section 2
