Polarization-insensitive optical amplifiers using tensile-strained quantum wells

Polarization-control issue in the semiconductor laser amplifier (SLA) is very important for its integration with optics such as waveguide-based devices. So far, two types of approaches have been tried for the polarization insensitive amplification in the SLA. Propagation characteristics of active waveguide was controlled to accomplish polarization-insensitive amplification through a controlled optical confinements for TE- and TM-mode. A square shaped active waveguide was employed in a polarization-insensitive SLA. Another approach is based on the modified electronic structure by strain, which can control electronic transitions for the TE- and the TM-modes. We have proposed and demonstrated a polarization-insensitive SLA with a tensile-strained MQW structure at 1.5 μm band. In this paper, we describe the polarization insensitive SLA using the tensile-strained InGaAsP-InGaAsP MQW structure as active layer material. The optimization of device structure and strain is discussed toward the polarization-insensitive amplification