흡수격자를 갖는 DFB 레이저의 제작 및 특성

Fabrication and Characteristics of DFB Laser with Absorptive Grating

New type of 1.3㎛ DFB laser diode with absorptive grating layer of 1.55㎛ InGaAsP was fabricated. The threshold current was about 24 mA. This laser shows self-plusation for DC operation. At low of injection the relation between the pulsation frequency and the injection current shows behavior similar to the relaxation oscillation of ordinary laser diode. At high level of injection the pulsation frequency decreases compared to the relaxation oscillation. Period doubling, tripling and quadrupling were observed in AC modulation. In case of period doubling the wave form shows only one extremely short pulse within double period of the modulation current pulse without any accompanying subsidiary pulese and the oscillation frequency was quite stable. The pulse widths as short as 58.5ps was observed in that case. We suppose that this characteristics of the DFB laser diode with absorptive grating will be applicable to the modulation methods of time division multiplexing.