Optical networking by DLP-based switched blazed grating

Abstract

All-optical modules are devices which process and transport optical signals without transforming to electronic signals. They get more attention as the optical communication network becomes more and more complicated. Among them, OADM (optical add drop module) is one of the most important devices in the optical DWDM (dense wavelength division multiplex) network. It plays the role of a node in network to upload/download signals or to route signals for optical performance monitoring. Applied broadly in projection display systems, DLP TM (Digital Light Processing TM ) from Taxes Instruments turns out to be a versatile device for optical signal processing. The working principle of DLP is based on so called switched-blazedgrating. Part of its micro-mirror array can be formed as a dynamic blazed grating with a period of 14 µm by tilting the micro-mirrors at an angle of ± 12 degrees. It is expected to function as either a switch or an attenuator by directing total or part of the incident light between the 2 nd and -2 nd diffraction orders. In this paper, we investigate the optical characteristics of a switched-blazed-grating, its application as a re-configurable OADM, and the performance of such a device. Ray tracing and optical analysis of the OADM are made by using package software ASAP TM from Breault Research Organization. In conclusion, as a mature and reliable MEMS device, DLP TM -based switched-blazed-grating provides a very versatile platform for digital optical signal processing and can be used as a dynamic optical-networking device with good performance.

Diffraction analysis of digital micromirror device in maskless photolithography system

“…8 Because of the periodical configuration and the coherence of the light source, the irradiance of the DMD is influenced by diffraction effects. 9 Even though several researchers have investigated DMD's diffraction, [9][10][11][12][13][14] there are still several issues which have not been fully understood. 9 Even though several researchers have investigated DMD's diffraction, [9][10][11][12][13][14] there are still several issues which have not been fully understood.…”

“…10 Evaluation of the diffraction efficiency is used to predict the exposure doses. In the general Fourier analysis of a DMD, 11,13,16 a single micromirror is considered as a rectangular function and the micromirror array is considered as a sampling function limited by the input pattern of the DMD. For example, errors of the DMD's manufacture and the precision of the machining of the optical mechanical structure influence the diffraction efficiency.…”