High gain and low operation current spot-size-converter integrated semiconductor optical amplifier for switching gate application

Spot-size-converter integrated semiconductor optical amplifiers have been developed as gate elements for optical switch matrices and an S-shape waveguide has been introduced to prevent re-coupling of unguided light to the output fiber. It was found that an angled-facet structure effectively suppressed light reflection at the end facets. Consequently, a high extinction ratio of 70 dB and a high fiber-to-fiber gain of 20 dB with gain saturation of 4.5 dBm were achieved. Sufficient optical coupling characteristics to a flat-ended single-mode fiber with a coupling loss of 3.5 dB were also demonstrated.