Semiconductor optical device on an indium phosphide substrate for long operating wavelengths

Abstract

A semiconductor optical device such as a laser or semiconductor optical amplifier (SOA) based on an indium phosphide substrate or equivalent buffer layer. The active layer of the device is based on conventional InGaAs(P) alloy, but additionally includes N in order to increase the operating wavelength to greater than 1.5 μm, preferably to a wavelength lying in the C- or L-band. The active layer composition may thus be denoted InGaAsNPwith x≧0.48, y≦1−z−p, z≦0.05, p≧0. The active layer may include a quantum well or multi-quantum wells in which case its thickness is preferably less than the critical thickness for lattice relaxation. In other embodiments the active layer is a 'massive' layer with quasi-bulk properties. The active layer may advantageously be under tensile stress, preferably roughly between 1% and 2.2%, to manipulate the light and heavy hole bands. The active layer is typically bounded by barrier layers made of a suitable semiconductor alloy, such as AlInAs or InGaAs(P).