Design and Analysis of Novel O-Band Low Polarization Sensitive SOA Co-Integrated With Passive Waveguides for Optical Systems

Abstract

Low polarization-dependent semiconductor optical amplifiers (SOAs) with an easy fabrication process and the capability to be co-integrated with passive elements are crucial in photonic integrated circuits. In this work, we design, simulate, and optimize a low polarization-dependent bulk SOA based on a novel layerstack with an unstrained bulk active layer with a robust and easy fabrication process that allows the co-integration with passive waveguides. The designed layerstack shows that the reflection between SOA and the passive waveguide is less than 1.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> . Furthermore, by designing the ridge waveguide and layerstack (thickness of the core and cladding layers), the confinement factor of TE- and TM- modes (Г <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TE</sub> / <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sub> ) are engineered to be approximately the same. This results in a low polarization-dependent SOA (since for the active bulk layer, the material gain of TE-mode is very close to the material gain of TM-mode). Numerical assessment of different length SOAs in terms of gain, polarization-dependent gain (PDG), noise figure are extensively investigated. Moreover, a booster SOA (1100 μm) with higher output saturation power has been investigated by widening the width of SOA from 1 μm to 3 μm. The output saturation power at 10 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> increases from +7.6 dBm to +13.9 dBm, when the width of the SOA waveguide increases from 1 μm to 3 μm. Finally, we discuss the fabrication tolerance on SOA characteristics. We show that the PDG strongly depends on the cladding layer thickness tolerance and decreases from 2.3 dB to 1.3 dB as it changes from 135 nm to 175 nm.