High-gain array of semiconductor optical amplifier integrated with bent spot-size converter (BEND SS-SOA)

We propose a high-gain semiconductor optical amplifier with an integrated bent spot-size converter (BEND SS-SOA). A straight active waveguide enables us to use a pn-buried heterostructure (pn-BH) with a high current-blocking effect and uniform characteristics. We can optimize a bent spot-size converter waveguide to provide low optical feedback from the facets and high-coupling efficiency to a flat-end optical fiber with low radiation loss due to the bend. The devices we fabricated achieve a high fiber-to-fiber gain of 18 dB with a coupling efficiency of -3.5 dB, and we have demonstrated a four-channel array with uniform characteristics.