Off-resonance properties of a photoelastic modulator

Karlton Crabtree, Neil Beaudry, Russell Chipman

Research output: Contribution to journalConference articlepeer-review


Polarization modulation in photo-elastic modulators (PEM) driven on and off resonance has been investigated for a commercially available PEM using a high speed infrared (lambda=1550 nm) polarimeter. Off-resonance operation was explored in the hope of finding a slower operating mode than the primary resonance. The primary resonance, used for normal PEM operation, was 5 Hz wide with a Q of 8500. The phase transfer function was well behaved and typical of electrical resonances. Device startup and shutdown had smooth amplitude changes occurring over 1/3 rd of a second. The photo-elastic modulator was examined at drive frequencies significantly below the resonant frequency. Driving the PEM with several odd sub-harmonics generated resonance at the fundamental frequency. Three other lower frequency resonances were discovered, but all at an oscillation amplitude more than 12 db below the amplitude of the fundamental resonance. Thus a practical configuration to allow slower operation of the PEM was not found.

Original languageEnglish (US)
Article number58880A
Pages (from-to)1-6
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Dec 29 2005
EventPolarization Science and Remote Sensing II - San Diego, CA, United States
Duration: Aug 2 2005Aug 4 2005


  • Photo-elastic modulator
  • Polarimetry
  • Polarization modulation
  • Retardance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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