MONOLITHIC INTEGRATED WAVELENGTH DEMULTIPLEXER BASED ON A WAVE-GUIDE ROWLAND CIRCLE GRATING IN INGAASP INP/

We present detailed modeling and experimental results for an improved design of an InGaAsP/lnP wavelength demultiplexer based on a monolithi cally integrated Rowland circle grating. The design incorporated ten w avelength channels at 1.55 mu m with a uniform spacing of 2 nm. The to tal on-chip loss was about 10 dB and the crosstalk between adjacent ch annels was as low as -25 dB. It was shown that low-loss etched turning mirrors can reduce the total on-chip loss by about 4 dB compared to t raditional 90 degrees curved multimode waveguides. By replacing standa rd hat grating facets with retro-reflecting V-shaped facets in the ech elle grating, the loss was further reduced by 4 dB, Polarization indep endent operation within a passband of 0.5 nm was achieved by using mul timode output waveguide, The potential sources producing the crosstalk have been analyzed and fabrication modifications for further improvem ent are suggested.