SAKAGUCHI Takahiro Tokyo Institute of Technology, Precision and Intelligence Lab., Research Assistant, 精密工学研究所, 助手 (70215622)
KOYAMA Fumio Tokyo Institute of Technology, Precision and Intelligence Lab., Professor, 精密工学研究所, 教授 (30178397)
Low cost and high performance lasers are required in next short distance lightwave networks and optical LANs. The vertical cavity surface emitting laser (VCSEL) is important light source and the VCSEL with 1.1-1.6μm of wavelength is suitable for the optical fiber systems. This research is aiming to realize the long wavelength VCSEL for optical data links using GaAs based material.
As GaAs based materials, highly strained GaInAs quantum well (QW), GaInNAs QW, GaInNAs quantum dot (QD) and GaInAsSb QD are grown using CBE, MBE and MOCVD epitaxial techniques for realizing high emission efficiency and long wavelength emission. 1.1-1.2μm emission by GaInAs QWs, 1.2-1.4μm by GaInNAs QWs, and 1.4-1.5μm by GaInAsSb QDs were observed from photoluminescence measurement of grown crystals. These results indicate applicability of GaAs based material for long wavelength lasers. It was also found that GaInNAs QDs were effective in high-density dot formation which is advantageous for improving in the laser characteristics. The edge emitting lasers are grown and fabricated using highly strained GaInAs and GaInNAs QWs and the lasing at 1.2μm and 1.4μm, respectively were observed. In addition, a 1.13μm wavelength VCSEL was fabricated by highly strained GaInAs QWs. The VCSEL was operated under high temperature and the long-distance high-speed tr'ansmission experiment was demonstrated. These initial lasing performances suggest applicability of GaAs based long wavelength material to the high performance VCSELS. Although, the VCSEL beyond 1.2μm of wavelength is not realized, 1.1-1.5μm VCSELS on GaAs will be achieved by improving emission efficiency of crystals by optimization of growth conditions.