<title>Planar optic polarization insensitive wavelength demultiplexer</title>

Abstract

Planar optical systems provide an efficient way to integrate multiple optical components into a compact optical substrate. Both lithographically formed surface relief gratings and holographically formed volume gratings have been used to implement diffractive optical elements in planar optic systems. These systems and sub-assemblies are useful for local distribution of optical signals in optical interconnect and other information processing applications. However when signals are propagated over distance greater than 5 - 10 cm alignment, beam diffraction effects, and substrate uniformity become major issues that limit signal fidelity. One approach to solving this problem is to combine free-space planar optic local distribution systems with fiber optic waveguides for long distance signal transfer. This extension provides a framework for integrating data communication and network environments to realize new forms of distributed information processing architectures. Additional signal capacity and effective data transfer rates can be obtained by incorporating wavelength multiplexing and de-multiplexing techniques in the interconnect system. However, diffractive type planar optical elements typically require high spatial frequency gratings that are sensitive to the polarization state of the incident optical beam. This property can have significant impact on the bit error rate of signals transmitted through hybrid fiber/planar optical distribution systems. In this paper we compare the polarization properties of surface relief and volume gratings for planar optic wavelength demultiplexing operations.