Performance and fabrication of ultra-low-reflectivity semiconductor optical amplifier without antireflective coatings

Abstract

Tilted stripe 1.3-µm semiconductor optical amplifiers with internal gains in excess of 30 dB and facet residual reflectivities of less than −40 dB have been fabricated without the use of antireflective (AR) coatings. These values of facet reflectivity are nearly 20 dB lower than the best previously reported results for any uncoated device.1-4 The basic approach to reducing facet reflectivities is to tilt the waveguide relative to the cleaved facets1 by 7°. This technique has previously been reported to reduce the facet reflectivity to about −20 dB and, in combination with AR coatings, has yielded excellent results.2 However, Marcuse5 indicated that much lower facet reflectivities should be achieved without the use of AR coatings. To achieve the predicted low values of facet reflectivity, a single transverse-mode ridge waveguide semiconductor optical amplifier was designed. The purpose of this paper is to describe the excellent uncoated facet reflectivities and the performance achieved with the semiconductor optical amplifier operating at 1.3-µm wavelength and to discuss the pro-designed. The purpose of this paper is to describe the excellent uncoated facet reflectivities and the performance achieved with the semiconductor optical amplifier operating at 1.3-µm wavelength and to discuss the processing techniques developed to ensure reproducible single transverse-mode behavior.