**5. References**


23456789 Modulation frequency [GHz]

This book chapter reviews the application of multifunctional Semiconductor Optical Amplifier in microwave photonics optical communication links. The device shows proper performance during the theoretical and experimental study. The noise, the linearity, the bandwidth and the dispersion effect of the multifunctional SOA applied in an optical link are studied. SOAs are potential candidates for modulation and detection tasks in RoF systems as their capabilities for detection/modulation, and amplification at the same time. So, cost effective designs are possible only employing one device at the subscriber's unit. On the other hand, the multifunctional SOA can improve the performance of microwave

A. J. Seeds: Broadband Fibre-Radio Access Networks, in Proc. MWP 1998, Princeton, New

A. Ng'oma: Radio-over-Fibre Technology for Broadband Wireless Communication Systems,

Eindhoven: Technische Universiteit Eindhoven, 2005. Proefschrift. – ISBN 90-386-

Fig. 22. Measured RF responses of the optical link for different SOA parameters Length of the optical fiber=50km, Length of the reference optical fiber=4m, Optical wavelength=1550nm, bias current of the SOA=400mA, 200ma, 125mA, 100mA, Optical


Gain=15dB, 13.5dB, 4,5dB, -9.5dB

**4. Conclusion** 

**5. References** 

1723-2

400mA 200mA 125mA 100mA without SOA

photonic links thanks to its dispersion compensation function.

Jersey, USA, October 1998, pp.1-4

SOA bias current

Normalised Transmission [dB]


**6** 

*1Denmark 2Germany* 

**Red Tunable High-Power** 

**Narrow-Spectrum External-Cavity** 

Mingjun Chi1, Ole Bjarlin Jensen1, Götz Erbert2, Bernd Sumpf2 and Paul Michael Petersen1

**Diode Laser Based on Tapered Amplifier** 

*1Department of Photonics Engineering, Technical University of Denmark, 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik,* 

Diffraction-limited high-power narrow-spectrum red diode lasers are attractive for many applications, such as photodynamic therapy, laser display, and as a pump source to generate UV light by second harmonic generation (SHG). High-power, diffraction-limited diode lasers can be realized by the technology of lasers with a tapered gain-region (Kintzer et al., 1993; Donnelly et al., 1998; Wenzel et al., 2003; Paschke et al., 2005; Sumpf et al., 2009; Fiebig et al., 2010). The tapered laser devices can be used in applications where narrowspectrum is not needed such as photodynamic therapy, but for other applications such as a pump source for UV light generation, the spectral quality of these devices has to be

In order to improve the spectral quality of a tapered laser, different techniques are applied, such as a monolithically integrated master oscillator power amplifier by forming Bragg gratings in the semiconductor material (O'Brien et al., 1993, 1997a), injection locking to an external single-mode laser (Goldberg et al., 1993; Mehuys et al., 1993b; O'Brien et al., 1997b; Wilson et al., 1998; Ferrari et al., 1999; Spieβberger et al., 2011), and different external-cavity feedback techniques (Jones et al., 1995; Cornwell & Thomas, 1997; Morgott et al., 1998; Goyal et al., 1998; Pedersen & Hansen, 2005; Chi et al., 2005; Lucas-Leclin et al., 2008; Tien et al., 2008; Sakai et al., 2009). Up to 1 W output power at 668 nm from a Fabry-Perot tapered diode laser was obtained with a beam quality factor of 1.7, and the spectral width was smaller than 0.2 nm (Sumpf et al., 2007). Around 670 nm, tunable narrow-linewidth diffraction-limited output was also achieved from an injection-locking tapered diode laser system seeded with a single-mode external-cavity diode laser (Häring et al., 2007); the output power was up to 970 mW. A 670 nm micro-external-cavity tapered diode laser system was demonstrated with a reflecting volume Bragg grating as a feedback element; in continuous wave (CW) mode, more than 0.5 W output power was obtained, and in pulse mode, 5 W peak power was obtained with a beam quality factor of 10 and a spectral width below 150 pm (Tien et al., 2008). Up to 1.2 W output power at 675 nm from a tapered laser

**1. Introduction** 

improved.

T.Marozsák, "Transmission Characteristics of All Semiconductor Fiber OpticLinks Carrying Microwave Channels", European Microwave Conf., Paris, France, 2000, vol.2, pp.52-55.
