1.55 μm spot-size converter integrated polarization-insensitive quantum-well semiconductor optical amplifier with tensile-strained barriers

A 1.55 mum polarization-insensitive lateral tapered spot-size converter integrated semiconductor optical amplifier (SSC-SOA) with tensile-strained barriers was investigated. The optical amplifier structure used a conventional ridge guide for the active layers and a second larger ridge for the passive waveguide. Low beam divergence of 12degrees x 15degrees results in about 3.1 dB coupling losses with -1 dB positional tolerances of +/-2.3 mum and +/-1.6 mum in horizontal and vertical directions using an anti-reflection coated flat-ended single-mode fibre. The active layer of SSC-SOA consisted of a tensile-strained barrier multiple-quantum-well structure. The SSC-SOA exhibited a signal gain of 25.5 dB and a saturation output power of 11.2 dB m with excellent polarization insensitivity (less than 0.5 dB) at 200 mA.