Characteristics-improvement of QD semiconductor optical amplifier using rapid-thermal annealing process

Abstract

We investigated the effect of Rapid Thermal Annealing (RTA) process on Quantum Dot Semiconductor Optical Amplifiers (QD SOAs). The devices are composed of 30-layer stacks of InAs quantum dot by using strain compensation method. The lateral size and height of QD are 30 nm and 4 nm, respectively. Our QD SOAs have emission wavelengths within 1.5 μm-band. We applied RTA process to improve the characteristics of internal quantum efficiency (ηi ) and optical loss (αi ) of ridge laser diode for QD SOAs. In this case, the operating temperatures of RTA process were set at 600°C, 620°C, 640°C and 660°C for 30 seconds each. In addition, the devices are cleaved to form a cavity length at 0.06 cm, 0.08 cm, 0.10 cm, 0.12 cm and 0.14 cm. According to the L-I characteristic result of ridge laser diode structure for QD SOAs at 640°C, the best minimum threshold current ( Ith ) is 47.93 mA. Moreover, according to the plot between 1 ηd−1 (external quantum efficiency) and cavity length, we can optimize the internal quantum efficiency and optical loss for a ridge laser diode structure to be 66.39% and 9.87 cm-1 respectively at 640°C RTA’s temperature. Finally, The RTA process helps to achieve 1.4 times higher in internal quantum efficiency as well as a minimal increase in internal optical loss comparing to without RTA.