Single-mode semiconductor lasers based on quantum-nano-structures for low-power consumption and high functional operations.

点击翻译按钮获取中文摘要

GaInAsP/InP strained low dimensional quantum structure lasers have been studied both theoretically and experimentally as the low power consumption, high performance light sources. A new type of distributed reflector (DR) laser, fabricated by the same fabrication processes as those of quantum-wire lasers and distributed feedback (DFB) lasers with wirelike active regions, has also been studied. Results obtained in this research are as follows:(1) A GaInAsP/InP quantum wire DFB laser with the active region width of 30nm in the period of 240nm was realized by an electron beam lithography, CH_4/H_2-reactive ion etching and two-step organometnllic vapor-phase- epitaxial growth processes. By adopting low-damage fabrication processes for high-mesa stripe structures, a threshold current as low as 2.1 mA, which corresponds to a threshold current density of 176 A/cm2, and a differential quantum efficiency of 16%/facet were obtained for the stripe width of 3.4μm and the cavity length of 350μm unde … More r RT-CW condition. A single mode operation with the sub-mode suppression-ratio (SMSR) as high as 50 dB (a bias current of twice the threshold) was also achieved in the lasing wavelength of 1542nm.(2) A distributed reflector (DR) laser, which consists of the active DFB and passive DBR sections with a quantum-wire structure, was studied for the low threshold, high efficiency and stable single-mode operation. The DFB and DBR sections are integrated by using the energy blue shift due to the lateral quantum confinement effect. As a result, a threshold current as low as 1.2mA was obtained under RT-CW conditions. The maximum differential quantum efficiency at the front facet was realized to be 36%. Furthermore a sub-mA operation of a DR laser has been realized with a higher index coupling coefficient of 570 cm^<-1> utilizing a deep DFB grating region in the active section. A minimum threshold current of 0.8mA (threshold current density of 180A/cm^2) and the differential quantum efficiency from the front facet was 20% have been realized. Stable single mode characteristics were preserved with a SMSR value of 41 dB at a bias current of twice threshold current.(3) A single mode operation and a high characteristic temperature operation of 1599nm GaInAsP/InP quantum-wirelike DFB lasers were achieved by adopting the Bragg wavelength detuning from the gain peak of a 54nm quantum wire active regions with a period of 247.5nm. A single mode operation with the sub-mode suppression-ratio (SMSR) as high as 51 dB (a bias current of twice the threshold under RT-CW condition) was achieved. A fixed single-mode operation without a mode hopping over a temperature range between 10℃ and 85℃ was achieved. The minimum threshold current of 5.4mA (current density of 520A/cm^2) was obtained at 50℃. Moreover, the changes of threshold current densities and differential quantum efficiencies as low as±19% and 24%, respectively, were obtained. Less