Planar integration of a polarization-insensitive optical switch with holographic elements

Planar integration of various optical systems has been developed in recent years as a way to reduce alignment problems and to build small size, robust monolithic devices. We are currently developing a family of re-configurable planar systems based on polarization properties of 90 degrees diffraction gratings. This approach allows particular applications in optical interconnections, where waveguide properties of planar integrated systems are exploited. In this paper, we propose an efficient way to implement multistage network in a planar configuration in order to realize a polarization-insensitive 2 x 2 optical switch. The switch is a multilayered structure composed of a reflective polarizing hologram sandwiched between two planar substrates. Signals are coupled in and out of the switch by diffraction on substrate-mode holograms and their optical paths are controlled by total internal reflection in a liquid crystal cell. Holographic optical elements are recorded in high-index modulation Omnidex(TM) photopolymer film from DuPont de Nemours. Hologram properties, switch design and performances are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.