Arrayed waveguide grating having arrayed waveguide employing taper structure

Abstract

An arrayed waveguide grating for easily changing the ratio of distribution of an optical signal into the main optical signal and the monitored optical signal is disclosed. In the device, an optical signal incident on an input waveguide is input into an arrayed waveguide via an input-side slab waveguide and is divided into main optical signals having different wavelengths in the arrayed waveguide with respect to a diffraction order m (natural number), and the divided optical signals are transmitted through an output-side slab waveguide and converged on output waveguides. The device has monitoring waveguides for monitoring optical signals having corresponding wavelengths of the main optical signals, where the monitored optical signals are diffracted in the arrayed waveguide with respect to a diffraction order m+i or m−i (i is a natural number), and the arrayed waveguide has a taper structure in the vicinity of the joint of the arrayed waveguide and the output-side slab waveguide, in which the width of each waveguide gradually changes along the direction of light transmission so as to adjust the ratio of distribution into the main optical signal and the monitored optical signal.