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

Journal Article · Fri Mar 14 04:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4867743· OSTI ID:22277910

Li, Jiaming ^[1]; Luo, Le; Carvell, Jeff; Cheng, Ruihua ^[2]; Lai, Tianshu; Wang, Zixin ^[1]

---

1. School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)
2. Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States)

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.

• OSTI ID: 22277910
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AIR
FARADAY EFFECT
IRON
LASER RADIATION
NOISE
POLARIMETRY
SENSITIVITY
THIN FILMS