Hybrid achromatic diffractive-Refractive Optics

Diffractive optical elements (DOEs) have great potential for use in a variety of photonic applications in communications and computer networks. One inherent limitation is their design for a specific, narrowband source. This requires actively controlled laser diode sources to maintain wavelength stability for compact photonic applications involving laser diodes. The finite bandwidth resulted in reduced image quality and diffraction efficiency. We propose a new class of achromatic DOEs that use two surface-relief elements with compensating optical properties. These DOEs will significantly relax the requirements for laser bandwidths and frequency stability. Because of the compensating effects of the two elements, the relief surfaces can be fabricated using a coarse tolerance process and the DOEs can be inexpensively manufactured. The relief surface produced is continuous so the efficiency of these DOEs is very high. The process tolerances allow the relief surface to be cast on one face of a refractive element enabling unique refractive/diffractive hybrids. In Phase I, we will construct a hybrid optic that demonstrates the achromatic performance and characterize its performance. Existing design techniques will be extended to incorporate the unique features of these hybrid achromatic DOEs. In Phase II, the manufacturing techniques will be refined and hybrid optics fabricated for several wavelength regions.