Wavelength demultiplexer using GaInAs-InP MQW-based variable refractive-index arrayed waveguides fabricated by selective MOVPE

A GaInAs-InP multiple quantum well (MQW)-based wavelength demultiplexer composed of an arrayed waveguide in which the refractive index varies across the array was fabricated. Since optical path length differences between waveguides in the array are achieved through refractive-index differences that are controlled by SiO₂ mask design in selective metal-organic vapor phase epitaxy (MOVPE), straight waveguide gratings having reduced optical propagation losses can be achieved. Furthermore, by employing MQW waveguides, variations in the refractive index may be induced through an applied electric field, allowing the device to manipulate wavelengths dynamically. A straight arrayed waveguide device having a 1.4% difference in refractive index was fabricated using an asymmetric side mask via a single selective MOVPE growth. The achievement of a diffraction angle difference of 4.40° between wavelengths of 1520 and 1580 nm was confirmed experimentally. In addition, a preliminary wavelength demultiplexer with a wavelength separation of approximately 25 nm and a free spectral range (FSR) of approximately 100 nm was also fabricated.