Indium phosphide based integrated photonic devices for telecommunications and sensing applications

Abstract

Photonics is an exciting area of study that is situated at the cross-section of physics, material science, and electrical engineering. The integration of photonic devices serves to reduce the size, weight, power consumption, and cost of the photonics- based systems, whose applications can be as disparate in nature as communications and medicine. In particular, an integrated all-optical logic gate and wavelength converter for fiber-optic telecommunications and an integrated tunable laser for trace-gas sensing are investigated in this thesis. These devices are fabricated in the indium phosphide (InP) material system, which includes InP and the ternary/quaternary III-V semiconductors that can be grown closely lattice-matched on the InP substrate. The all-optical logic gate is designed as a Mach-Zehnder interferometer with semi- conductor optical amplifiers as active nonlinear elements that are optically coupled to the passive waveguides using the asymmetric twin waveguide technique. The device is grown and fabricated monolithically and carrier-dependent optical interference is demonstrated at the 1.55 [mu]m wavelength. The tunable diode laser is designed to operate in the wavelength range of 1.55 [mu]m - 2 [mu]m for trace-gas spectroscopic sensing and comprises of strained InGaAs quantum wells. The laser is monolithically fabricated using mask-less lithography techniques and tuning is demonstrated in Fabry-Perot cavity lasers under continuous-wave operation. A ring-coupled 2 [mu]m wavelength laser is designed that will exhibit a tuning range of tens of nanometers.