design of an angle detector for laser beams based on grating coupling设计基于光栅角探测器的激光束耦合.pdfVIP

Micromachines 2012, 3, 36-44; doi:10.3390/mi3010036 OPEN ACCESS micromachines ISSN 2072-666X /journal/micromachines Article Design of an Angle Detector for Laser Beams Based on Grating Coupling Tapas Kumar Saha 1, Mingyu Lu 1, Zhenqiang Ma 2 and Weidong Zhou 1,* 1 Department of Electrical Engineering, University of Texas at Arlington, Arlington, TX 76019, USA; E-Mails: tapaskumar.saha@ (T.K.S.); mingyulu@ (M.L.); 2 Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; E-Mail: mazq@ * Author to whom correspondence should be addressed; E-Mail: wzhou@; Tel.: +1-817-272-1227; Fax: +1-817-272-7458. Received: 24 December 2011; in revised form: 21 January 2012 / Accepted: 21 January 2012 / Published: 1 February 2012 Abstract: A novel angle detector for laser beams is designed in this paper. It takes advantage of grating coupling to couple the incident light into a slab waveguide; and, the incident light’s angle can be determined by reading the outputs of light detectors within the waveguide. This device offers fast-responding on-chip detection of laser beam’s angle. Compared to techniques based on quadrant photodiodes or lateral effect photodiodes, the device in this paper has far greater detectable range (up to a few degrees, to be specific). Performance of the laser angle detector in this paper is demonstrated by finite-difference- time-domain simulations. Numerical results show that, the detectable angle range can be adjusted by seve