In this paper we modeled and analyzed the ridge type InGaAlAs/InP semiconductor laser with lateral current confinement structure, and optimized the design for the ridge wave guide with the current confinement. We proposed and fabricated the ridge type InGaAlAs/InP laser with a cost effective selective undercut etching method and demonstrated the improvement of the ridge laser performance. This paper provides a solution to solve the cost/yield issue for conventional BH (buried hetero-structure) type laser and performance issue for conventional ridge type laser.

Simulation and fabrication results on back-illuminated 4-channel photodiode (PD) array with a self-aligned micro ball lens are described. The channel pitch and diameter of each photosensitive area are 250 µm and 40 µm, respectively. Measured photocurrent is 1.92 times larger than that without a lens. Alignment tolerance between the single mode fiber (SMF) optical axis and the photodiode is improved from 21.2 µm to 42.7 µm. Moreover, the separation tolerance between the fiber and the lens is 210.5 µm. These large tolerances agree with simulation results, demonstrating that the device configuration is suitable for receivers for multi-channel inter-connection. Frequency response and inter-channel cross talk are also discussed.

The TJS lasers which have the kink-free behavior and good proportionalities in the outputs between the front mirror and the rear mirror have been tested by cw aging. After 12,000-hour cw againg, a TJS laser has been found to still lase in a single longitudinal mode as well as in the fundamental transverse mode. The life of TJS lasers at 25 is estimated to be at least 80,000 hours on the basis that the laser is still alive after 3,000-hour aging at 60. By considering that the spatial homogeneity in the active region of the TJS laser is maintained for long time cw aging, the reason why the single mode behavior is kept even after the aging can be explained. Here, the spatial homogeneity in the active region of the TJS laser may be due to a small size of the region and to high hole concentration of the region.