Virtually Imaged Phased Array

A Virtually Imaged Phased Array (VIPA) is a simple design of an optical element which shows large angular-dispersion versus wavelength change. It consists of a semi-cylindrical lens and a thin plate of glass on which reflection coatings are formed. Both theory and experiment show that the angular dispersion is about 0.5 deg/nm, which is large enough to demultiplex dense WDM channels. When the VIPA is used in a wavelength demultiplexer, the fiber coupling efficiency, which determines the insertion loss and the crosstalk, is important. The characteristics of the demultiplexer using the VIPA are analyzed. Temperature dependence of the demultiplexing performance is also an important issue. A temperature insensitive design of the VIPA is described. Another application of the VIPA is chromatic dispersion compensation in a fiber transmission line. The scheme for chromatic dispersion device using the VIPA is discussed. (Author)