1.5 mu m GaInAsP angled-facet flared-waveguide traveling-wave laser amplifiers

A broadband laser amplifier requires extremely low facet reflectivity (<0.1%). Previously, a low effective facet reflectivity of 0.05% was realized by an angle-facet structure in the 1.3- mu m wavelength band. Present work reports an improved structure for the 1.5- mu m wavelength band by flaring the waveguide ends near the angled facets. With a conventional antireflection coating of approximately 1% reflectivity, the measured effective facet reflectivity is less than 0.01% and the resultant devices have a fiber-to-fiber gain of 15 dB centered at 1.49 mu m.<
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