Large angular dispersion by a virtually imaged phased array and its application to a wavelength demultiplexer.

A new scheme that shows large angular dispersion is proposed and demonstrated. The key idea to this method is a virtually imaged phased array (VIPA). The angular dispersion of a VIPA is 10-20 times larger than those of common diffraction gratings, which have blaze angles of ~30 deg. With the VIPA, wavelength demultiplexing for 10 channels with 0.8-nm spacing is achieved. Low polarization-state dependence (~0.1 dB) is also confirmed.