Wavelength-multiplexing diffractive phase element with quantized phase structure

We have reported on the design algorithm of the wavelength-multiplexing dif fractive phase element (WMDPE) capable of generating independent spot patte rns for more than two wavelengths. [J. Opt. Soc. Am. A 18 (2001) 1082] In t his paper, the stepwise quantization method proposed by F. Wyrowski [J. Opt . Soc. Am. A 7 (1990) 961] is built into the algorithm to design the WMDPE with quantized phase structure. Validity of the method is verified by the W MDPE for 7 wavelengths with 9 phase levels. The optical experiment demonstr ates that the fabricated WMDPE generates correct patterns for different wav elengths. Performance dependence of the WMDPE on the number of quantized ph ase levels is discussed based on the simulation results.