Integrated optic wavelength demultiplexer using a coplanar grating lens

An integrated optic wavelength-demultiplexer (IOWD) is proposed and demonstrated. A coplanar grating lens in a single-mode slab waveguide is utilized for wavelength separating and focusing functions. The grating lens and input/output channel waveguides are monolithically integrated in a waveguiding film on a rectangular Si substrate. The IOWD was designed for demultiplexing nine wavelengths from 0.778 to 0.802 microm (3-nm separation) with less, similar-20-dB crosstalk. The device requires no additional collimating or focusing lenses and was fabricated by a planar process including an electron-beam writing technique. The demultiplexing principle is demonstrated by elementary experiments using single-mode laser diodes.