First tunable narrowband 1.55 µm optical dropfilter usinga dynamic photorefractive grating in iron doped indiumphosphide

Abstract

A tunable narrowband (FWHM = 2.5 GHz) 1.55 µm reflective drop filter is realised in an iron doped indium phosphide crystal. The index grating results from the photorefractive effect via an interference pattern. The grating period is determined by the wavelength of the laser diode which provides the two counter-propagating writing beams.