Differential processing using an arrayed-waveguide grating

This paper reports on time-space conversion-based differential processing o f optical signals using a high-resolution arrayed-waveguide grating (AWG) a nd a spatial filter at a wavelength of 1.55 mu m. We clarify the advantages of the AWG device and show where it is applicable. In order to reduce loss at the spatial filter, we propose a new phase-only filter that functions a s a differential filter. The difference between the exact differential filt er and the proposed phase-only filter is calculated theoretically. We confi rm experimentally that the optical pulse can be differentiated by the propo sed filter. For application of differential processing, we also proposed a phase modulation to amplitude modulation (PM-AM) conversion and demonstrate d the PM-AM conversion at 10 Gbit/s signals using a PSK-nonreturn-to-zero ( NRZ) format.