**8. References**


**2** 

*China* 

**980nm Photonic Microcavity Vertical** 

Vertical-Cavity Surface-Emitting Laser (VCSEL) is a type of semiconductor laser with laser beam perpendicular to the surface of the semiconductor substrate, as shown in Fig.1(a) [1]. VCSEL has many advantages, such as non-divergence output beam, fabrication and test on wafer, easy two-dimensional integration, and single longitudinal mode work. VCSEL is composed of an active region sandwiched between top and bottom highly reflective DBR mirror [2,3]. Generally high power VCSEL could be realized through large emission window, but suffers multi-mode operation due to the inhomogeneous current distribution across the active region. On the other hand single-mode operation is required in many applications including optical communications. Single-mode can transport longer distance and meet the requirements of high-speed data transmission [4,5]. Several approaches such as confined aperture less than 3m, proton implantation, oxide and proton implantation mixed structure have been reported to achieve single-mode VCSEL. Due to the small aperture of emission window, these VCSELs are lasing at low output power. Besides the requirements of high output power and single mode operation, the wavelength range of VCSEL is broadened by applying InAs quantum dots or InGaAsN quantum well of the wavelength range of 1300nm and nitride quantum well of the blue light range for the applications of fiber communication

In the past few years photonic crystal materials became of a great interest due to their powerful properties allowing for previously unknown flexibility in shaping the light. On the contrary to conventional edge emitting laser, the cavity length of VCSEL is of the size of optical wavelength. This brings VCSEL actually into microcavity field, where spontaneous emission is believed not to be an intrinsic atomic property anymore. Spontaneous emission can be enhanced or inhibited by tailoring the electromagnetic environment that the atom can radiate into. In a conventional edge emitting laser made of large cavity, most of the spontaneous emission is lost to free space as radiation modes and only a small fraction couples to the resonant mode of the cavity formed by the mirrors. Therefore, significant stimulated emission output can only be obtained when the input power crosses a threshold to overcome the free-space loss. In a wavelength-sized microcavity, the photon-mode density develops singularities, just as in the case of carrier confinement in quantum well. In this case, a single spectrally distinct mode can receive most or all of the spontaneous

**1. Introduction** 

and display.

**Cavity Surface Emitting Laser** 

*Changchun Institute of Optics, Fine Mechanics and Physics* 

Yongqiang Ning and Guangyu Liu

*Chinese Academy of Sciences Changchun* 

