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Title: Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling

We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10{sup −9} rad/√(Hz), which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10{sup −9}rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film.
Authors:
 [1] ;  [2] ; ; ;  [3] ; ;  [1]
  1. School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)
  2. (United States)
  3. Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States)
Publication Date:
OSTI Identifier:
22277910
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AIR; FARADAY EFFECT; IRON; LASER RADIATION; NOISE; POLARIMETRY; SENSITIVITY; THIN FILMS