Gain and noise characteristics of 25-layer stacked quantum dot-semiconductor optical amplifiers in the communication wavelength band

Abstract In this study, a 25-layer stacked quantum dot (QD) semiconductor optical amplifier was fabricated using the strain compensation technique with an InP(311)B substrate. The highly stacked InAs QD layers enhanced the gain and output in the communication wavelength band. During pulsed operation, an extremely high gain of 36.9 dB and a saturated output power of 17.9 dBm were confirmed. In addition, sufficient gain was confirmed across the C-band and a part of the L-band. The measured noise figure (6.2 dB) was comparable to the generally accepted low-noise threshold of 5 dB, and its temperature stability was maintained up to 45 °C. However, performance limitations due to thermal effects were observed during direct-current operation. Further improvements in the device structure are required to reduce the thermal effects and enhance the output.