ATHERMALIZATION AND PRESSURE DESENSITIZATION OF DIFFRACTION GRATING BASED WDM DEVICES

摘要

A wavelength division multiplexer/demultiplexer (WDM) for use in an optical network and in an optical performance monitor that minimizes increases in insertion losses over temperature variations. The WDM has a structure for holding at least one optical component. A diffraction grating assembly havin g a substrate is held in relation to the at least one optical component by the structure. A lens assembly having a focal length is held in relation to the at least one optical component. The coefficient of thermal expansion of the len s assembly and structure are approximately equal. The lens assembly is constructed from a material chosen to minimize its variance in focal length over temperature. The grating assembly has an angular dispersion that change s with temperature and the product of the focal length and angular dispersion remains constant over temperature. The WDM further comprises a prism having a change in index of refraction with temperature that is approximately equal t o a negative of a coefficent of thermal expansion of the substrate. The substrate has a coefficient of thermal expansion approximately equal to a negative of a coefficient of thermal expansion of air.