Linear variable optical attenuators with shaped-finger comb-drive actuators

HAH D.

APPLIED OPTICS, vol.59, no.2, pp.277-284, 2020 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 59 Issue: 2
  • Publication Date: 2020
  • Doi Number: 10.1364/ao.59.000277
  • Journal Name: APPLIED OPTICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Applied Science & Technology Source, Aquatic Science & Fisheries Abstracts (ASFA), Communication Abstracts, Compendex, EMBASE, MEDLINE, DIALNET
  • Page Numbers: pp.277-284
  • Abdullah Gül University Affiliated: Yes

Abstract

A design method is proposed for variable optical attenuators (VOAs), aiming at linear attenuation-voltage characteristics, and verified by finite element analysis. Devices of interest are planar VOAs based on microelectromechanical systems technology, with either a knife-edge shutter or a reflector. The proposed method calculates the shape of the fingers of the comb-drive actuators that are used to move the optical component (shutter or reflector) to change the attenuation level. The calculation is, in effect, tantamount to solving a differential equation that encompasses the optical model of the device, electromechanical behavior of the actuators, and the objective of the design, i.e., linear attenuation-voltage characteristics. The design method is almost all-analytical with minimum usage of numerical analysis. The obtained designs are further examined by three-dimensional finite element analysis to understand their effectiveness and to probe the validity of the approximations used. The best linearity factor (defined as % deviation from the ideal case) obtained is 1.34% for both shutter- and reflection-type devices when the conditions are set as 1-dB insertion loss and 50-dB maximum attenuation. (C) 2020 Optical Society of America