Slab -coupled buried waveguide high power semiconductor laser and optical amplifier

Rapid development in the optical communication created large demands of high-performance, high-efficiency, low-cost optoelectronic devices. The semiconductor laser and the semiconductor optical amplifier are two of the most important and attractive devices for optical communication applications. However, current semiconductor optical amplifiers exhibit large crosstalk in multi-channel communication systems, which heavily limits their deployment. Traditional buried hetero-structure semiconductor laser has a low output power, and a large coupling loss to the single mode fiber due to the mode mismatch.;This thesis research focused on developing novel semiconductor materials and waveguide structures to improve the device performance. It was aiming at a full research program of design, growth, fabrication and characterization of the semiconductor laser and semiconductor optical amplifier. The technical approach is based on advanced metal organic chemical vapor deposition technologies, photolithography, selective etching, photoluminescence spectroscopy, and electro-magnetic wave theory.;Indirect band gap materials, including n-i-p-i doping structure, GaAs/AlAs superlattice structure, and InGaAsP/InGaAlAs type II multi-quantum well (MQW) structure were investigated. My study showed that electrons and holes in semiconductor materials can be separated in space by ion induced electrical field or band discontinuity. The two recombination channels, direct and indirect, have been observed. An InGaAsP/InGaAlAs type II MQW material with the indirect recombination peak dominant PL and EL spectra at room temperature was successfully grown. The measurement showed that this material has longer carrier lifetime of 18 ns, compared to 10 ns in type I InGaAsP/InGaAsP MQW material. This type II MQW material is an excellent candidate for the low-crosstalk, low-phase-noise semiconductor optical amplifier.;I designed a slab-coupled buried waveguide laser structure, and successfully fabricated the robust single spatial mode semiconductor laser with large near circular mode profile. A butt-coupling efficiency of 59% to single mode fiber was achieved. The -1 dB alignment tolerances with cleaved fiber were ±3.25 μm and ±1.80 μm in the parallel and perpendicular directions to the PN junction. The highest laser output power achieved was 116 mW per facet in CW mode, and 200 mW per facet in pulse mode.