Tunable Spectral Devices Based on Planar Holographic Diffractive Structures

Combining photonic components into a single integrated optical chip usually requires channel waveguides, which are difficult to fabricate and have high losses. Therefore, DARPA is seeking device technology for two-dimensional holographic diffractivestructures in planar waveguides that efficiently connect multiple input-output port pairs. Lithographic scribing of these devices followed by low-cost stamping or etching into optoelectronic materials promises devices that are extremely robust and immuneto point defects. However, their implementation in complex yet flexible fully 2D photonic devices for spectral filtering, target discrimination and other applications will require dynamically tunable on-chip holographic elements. In response, to thisDARPA need Physical Optics Corporation (POC) proposes to develop a new electro-optically tunable Active Planar Holographic Diffractive Structure (APHODS) technology combining standard lithography with holographic nanostructuring. It combines electro-opticmaterial such as liquid crystal polymer with surface relief structures in planar waveguides to create a high speed, low voltage electrically-tunable, fully 2D planar diffractive structure. In Phase I, POC will demonstrate the feasibility of APHODS bymeans of a simple tunable grating device. Phase II will culminate in a fully packaged 2D planar holographic device for spectral filtering and processing applications, leading to a manufacturing ready device in Phase III. The incorporation of coherentspectral filtering and spectral target recognition, into a single chip will have enormous benefits to a number of military and commercial applications. With the U.S. military's increasing use of photonic technologies, the development of APHODS will becritical for homeland security. Initial applications are envisioned in advanced optical code division multiplexing and many other types of all-optical processing. Optical integrated circuits of commercial importance include waveguides, emitters,detectors, modulators, and spatial wavefront control devices, all in the plane of the waveguide. Use of fully 2D planar waveguide circuits allows powerful integration of all these functions in a single planar waveguide.