Design and fabrication of InP-based passive mode-locked multisection diode lasers

The primary aim of effective communication is to deliver the intended messages to the other party in the most secure and fastest way possible. In optoelectronic communication, semiconductor (diode) lasers have begun to be used as light sources, and one reason these lasers are significant light sources in fiber optic communication systems is that they enable information transfer through very short and high-power optical pulses, minimizing distortion in the transmitted data. While an attenuation of 0,5 dB/km is achieved at 1350 nm, it is 0,2 dB/km at 1550 nm. To produce diode lasers that emit short-duration and high-power optical pulses, multi-section structures with different functions are developed over the cavity. In fiber optic communication systems, the number of repeaters is reduced by using high-power lasers, thereby minimizing the dispersion of optical information. Additionally, by generating very short optical pulses, it is possible to transmit more optical information, which increases bandwidth. In this thesis, different configurations of diode lasers with gain and absorption sections were designed and fabricated by keeping the cavity length short (<500 μm) using InGaAsP/InP (1350 nm) and AlGaInAs/InP (1550 nm) material structures. Characterization measurements as light output-current (L-I), current-voltage (I-V), optical spectrum and optical pulses were conducted on the produced lasers.