Quantum Well Laser Diodes With Slightly-Doped Tunnel Junction

We experimentally investigate the electrical and optical characteristics of conventional quantum well laser diodes and the quantum well laser diodes with slightly-doped tunnel junction N++GaAs/undoped-GaAs. The results show that the slightly-doped tunnel junction give significant role on the laser diodes performances in the InGaAs/GaAs quantum well material system. The TJ LD has a internal quantum efficiency of 21% and the loss is 6.9 em -1 , the current threshold is 35 mA, both the lasers are operating at 1.06 μm, but the slightly-doped tunnel junction diode show nonlinear S-shaped current-voltage and broadband lasing characteristics. The results may also lead to the realization of more applications

A hybrid single-mode laser based on slotted silicon waveguides

An InGaAsP-Si hybrid single-mode laser based on etched slots in silicon waveguides was demonstrated operating at 1543 nm. The InGaAsP gain structure was bonded onto a patterned silicon-on-insulator wafer by selective area metal bonding method. The mode-selection mechanism based on a slotted silicon waveguide was applied, in which the parameters were designed using the simulation tool cavity modeling framework. The III-V lasers employed buried ridge stripe structure. The whole fabrication process only needs standard photolithography and inductively coupled plasma etching technology, which reduces cost for ease in technology transfer. At room temperature, a single mode of 1543-nm wavelength at a threshold current of 21 mA with a maximum output power of 1.9 mW in continuous-wave regime was obtained. The side mode suppression ratio was larger than 35 dB. The simplicity and flexibility of the fabrication process and a low cost make the slotted hybrid laser a promising light source

Asymmetric quantum well broadband thyristor laser

A broadband thyristor laser based on InGaAs/GaAs asymmetric quantum well (AQW) is fabricated by metal organic chemical vapor deposition (MOCVD). The 3-μm-wide Fabry–Perot (FP) ridge-waveguide laser shows an S-shape I−V characteristic and exhibits a flat-topped broadband optical spectrum coverage of ~27 nm (Δ−10 dB) at a center wavelength of ~1090 nm with a total output power of 137 mW under pulsed operation. The AQW structure was carefully designed to establish multiple energy states within, in order to broaden the gain spectrum. An obvious blue shift emission, which is not generally acquired in QW laser diodes, is observed in the broadening process of the optical spectrum as the injection current increases. This blue shift spectrum broadening is considered to result from the prominent band-filling effect enhanced by the multiple energy states of the AQW structure, as well as the optical feedback effect contributed by the thyristor laser structure

High-performance electroabsorption modulator

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 two-step 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

A 10-GHz Bandwidth Electroabsorption Modulated Laser by Ultra-Low-Pressure Selective Area Growth

A novel integration technique has been developed using band-gap energy control of InGaAsP/InGaAsP multiquantum-well (MQW) structures during simultaneous ultra-low-pressure (22 mbar) selective-area-growth (SAG) process in metal-organic chemical vapour deposition. A fundamental study of the controllability of band gap energy by the SAG method is performed. A large band-gap photoluminescence wavelength shift of 83nm is obtained with a small mask width variation (0-30μm). The method is then applied to fabricate an MQW distributed-feedback laser monolithically integrated with an electroabsorption modulator. The experimental results exhibit superior device characteristics with low threshold of 19mA, over 24 dB extinction ratio when coupled into a single mode fibre. More than 10 GHz modulation bandwidth is also achieved, which demonstrates that the ultra-low-pressure SAG technique is a promising approach for high-speed transmission photonic integrated circuits