The Study Of Semiconductor Ring Laser

Compared to the traditional Fabry-Pérot semiconductor laser, semiconductor ring laser (SRL) employs the ring waveguide and bus waveguide to realize optical resonant cavity and laser output, respectively. On the one hand, there is no need of facet and grating to realize lasing for SRL. On the other hand, SRL exhibits outstanding optical bistable characteristics due to the two counter-propagating laser in the ring cavity. Therefore, SRL is considered as the most promising building block to realize all-optical flip-flop and logic elements, because of its potential for size reduction in monolithic integrated. There has been a continually increasing interest in SRL applications, such as integrated optical source, laser gyroscope, optical SRAM and optical switch.In this thesis, employing 1550nm lasing wavelength and InP based epitaxial wafer, we have fabricated the semiconductor ring lasers successfully, which exhibit excellent unidirectional bistable operation. The main contents of this paper are as follow.The AlGaInAs/InP quaternary materials structure, which employs graded index separate confinement heterostructure (GRINSCH) and tensely strained multi-quantum-well, is adopted in this work. Because, Al-quaternary materials have a lower carrier leakage and a higher characteristic temperature, the GRINSCH is included to generate a much smaller carrier population in the optical core layer, and tensely strained multi-quantum-well could reduce the laser threshold current greatly.We design two kinds of resonant cavity– ring and racetrack, and the both circumferences of them are 2176μm which could meet the 40Gbit/s optical communication. We also design two kinds of ridge waveguide– shallow etching (2010nm) and deep etching (4170nm) - with single transverse mode operation, and we expect that each of them has different optical confinement ability. We design the bus waveguide elaborately, to reach minimal bending losses for low threshold current lasing and the low back-reflection couplers for robust unidirectional operation. At last, the PD electrodes are designed on the bus waveguide to detect the output optical current. In the processing of semiconductor ring laser, a complete fabrication process flow is given and electrical isolation groove, reactive ion etching of ridge waveguide and planarization are discussed in detailed.The electrical performances of the semiconductor ring laser are tested by the I-V characteristics, in which the forward voltage is 0.5V and reverse breakdown voltage is 10V.The optical performance of the semiconductor ring laser are tested by P-I and spectrum characteristics. The shallow etching ring lasers have demonstrated robust unidirectional bistable operation and the threshold is 55mA. The output optical spectrums have also exhibited 1569.65nm lasing wavelength, 25dB side mode suppression ratio and 033nm free spectral range (the spectral interval of two adjacent longitudinal mode), which could meet 40Gbit/s optical communication.