Wavelength Router Using Bridged Planar Spectrographs

We propose a device which has the same wavelength routing function as a conventional arrayed-waveguide-grating and consists of two planar waveguide spectrographs connected by waveguide array of equal-length. We fabricate the device using compound semiconductor for future integration of many functions. The fabricated device shows a filter width of 1.7 nm and a sidelobe level of -8 dB which is limited by the power distribution in the waveguide array. A device using the whispering gallery mode is also demonstrated. The whispering gallery mode is expected to reduce the phase error. The sidelobe level is reduced by over 5 dB as compared to a device using the conventional channel waveguide. Finally, a design for compensating the effect of the radius of curvature on the propagation constant is proposed.