title: Silicon-based transmissive diffractive optical element.
abstract: A silicon nitride (SiNx) membrane diffractive optical element (DOE) designed to exhibit beam-splitting and focusing behavior at visible wavelengths has been fabricated and tested. Since the fabrication process is based on silicon micromachining technology, the DOE is easily integrated with a laser diode chip and a photodiode chip on a silicon substrate to function as the hologram-laser-photodiode unit for use in the pickup head of a CD or DVD system. The SiNx film is deposited with low-pressure chemical-vapor deposition and the free-standing membrane is formed by KOH etching. The transmissive DOE showed a high diffraction efficiency (>20% for a binary-phase-level element). The experimental evaluation was in good agreement with the designed and modeled predictions.
authors.affiliation: Optical Science Center, National Central University, Jung-Li 320, Taiwan. jjlee@phy.ncu.edu.tw
authors.forename: Chien Chieh
authors.initials: CC
authors.lastname: Lee
authors.forename: Yu Cheng
authors.initials: YC
authors.lastname: Chang
authors.forename: Chih Ming
authors.initials: CM
authors.lastname: Wang
authors.forename: Jenq Yang
authors.initials: JY
authors.lastname: Chang
authors.forename: Gou Chung
authors.initials: GC
authors.lastname: Chi