Optimized quantization for diffractive phase elements by use of uneven phase levels

Many applications of diffractive phase elements involve the calculation of a continuous phase profile, which is The quantization process maps the cont inuous range of phase values to a limited number of discrete steps. We pres ent a new scheme with unevenly spaced levels for the design of diffractive elements and apply it to the design of intracavity mode-selecting elements. We show that this modified quantization can produce significantly better r esults than are possible with a regular or even the bias-phase-optimized qu antization scheme that we reported here earlier. In principle this process can be employed to a greater or lesser extent in any quantization process, allowing the fabrication of diffractive elements with much improved perform ance. (C) 2001 Optical Society of America.