In this paper, we report the high-temperature uncooled and high-speed directly modulated 1.3μm wavelength AlGaInAs/InP MQW-DFB ridge waveguide laser diodes. By optimizing the structure of active region based on AlGaInAs strained MQW, and the design of DFB grating, such as the position, coupling coefficient and the detuning with respect to the material peak gain, we have successfully fabricated high-speed and uncooled 1.3μm DFB laser diodes. Large bandwidth of 15GHz was achieved at room temperature. Large characteristic temperature of 80K and small degradation of slope efficiency of 1.2dB from 25°C to 85°C have been realized.
Three dry etching processes using a high ion density inductively coupled plasma (ICP) system in fabrication of optoelectronic device have been briefly presented in this paper. Smooth etched surface, high rate and selectivity ICP InP etching using Cl2/CH4/N2 have been demonstrated first time in fabrications of semiconductor laser. Low damage CH4/H2 ICP InP sub-micron grating etching using SiNx mask can be used for SG-DBR tunable laser fabrication. Anisotropic Cl2/CH4/Ar ICP etching with vertical profile has been used for GaAs/AlGaAs DBR layers etching in vertical cavity surface emitting laser (VCSEL) fabrication. The etching characteristics have been investigated by conventional optical microscopy and scanning electron microscopy (SEM).
We successfully fabricated the angled strip DC-PBH style SLED devices by using low damage ICP dry etching technology. The mesa of DC-PBH SLED was formed by Cl2/N2 ICP dry etching process. The low DC bias (<100 eV) of ICP etching technology can reduce the damage caused by ordinary RIE technique and Cl2/N2 based process can get rid of chemical damage caused by CH4/H2. High out-put power SLED device was obtained by using low damage ICP dry etching, the out-put power is 2 mW at 100 mA inject current (CW) at 25°C. Through optimized the angle of the active strip and AR optical film design, the full width of the half maximum (FWHM) of the spectrum at 2 mW out-put power can reach 46.4nm and the ripple of the SLED spectrum is low down to 0.4 dB.
This paper summarizes the recent advances and results of uncooled, high-speed directly modulated long-wavelength DFB laser diodes. It discusses ways of obtaining high temperature operation of laser diodes. By assessing the effect of carrier transport, doping and strain in active region, as well as the non-active region factor, such as laser waveguide properties and microwave parasitic parameters, various methods are discussed to improve the direct modulation bandwidth.