Current traveling-wave laser amplifiers rely on good antireflection coatings on both facets to prohibit the Fabry-Perot resonance. It requires extremely tight control on the refractive index and thickness of dielectric layers.1,2 A simpler way to suppress the Fabry-Perot resonance is to slant the waveguide (gain region) from the cleavage plane so that the internal light reflected by the cleaved facets does not couple back into the waveguide and is, therefore, lost [Fig. 1(a)]. The reflectivity for the lowest-order TE mode decreases exponentially with the slant angle θI.3 High-power GaAs superluminescent diodes have been made with 5° inclination.4,5 Here we report a broadband 1.5-μm InGaAsP traveling-wave laser amplifier (TWA) with angled facets.
© 1988 Optical Society of AmericaPDF Article