1.55-μm InGaAsP-InP two-section DFB lasers with varied ridge width, both gain-coupled and index-coupled, have been fabricated. Self-pulsations with frequencies around 40 GHz are observed. The related mechanism and the tunability of generated self-pulsations is studied.
A complex-coupled DFB laser with sampled grating has been designed and fabricated. The method uses the ＋ 1 st order reflection of the sampled grating for laser single-mode operation. The typical threshold current of the sampled grating based DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5385 μm, which is the ＋1 st order wavelength of the sampled grating.
A 1.55μm InGaAsP-InP three-section DFB laser with hybrid grating is fabricated and self-pulsations （SP） with frequencies around 20GHz are observed. The mechanism of SP generation in this device is researched. Furthermore,the important role of the phase tuning section on the SP is investigated.
A 100-μm-long electroabsorption modulator monolithically integrated with passive waveguides at the input and output ports is fabricated through ion implantation induced quantum well intermixing, using only a twostep low-pressure metal-organic vapor phase epitaxial process. An InGaAsP/InGaAsP intra-step quantum well is introduced to the active region to improve the modulation properties. In the experiment high modulation speed and high extinction ratio are obtained simultaneously, the electrical-to-optical frequency response （E/O response） without any load termination reaches to 22 GHz, and extinction ration is as high as 16 dB.
