Sensitive Faraday rotation measurement with auto-balanced photodetection

Chia Yu Chang*, Likarn Wang, Jow Tsong Shy, Chu En Lin, Chien Chou

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

25 Scopus citations

Abstract

A magneto-optic polarimetry based on auto-balanced photodetection is investigated. In this experiment, a commercial auto-balanced photoreceiver is adopted to measure the Faraday rotation of air. With a proper setup to utilize its noise cancellation capability, the measurement can be flexible and sensitive. The angular sensitivity is 2.9910-8 rad Hz-12, which is about 2.7 times the shot noise limit. The measured Verdet constant of air is 1.3910-9 rad G-1 cm-1 at 634.8 nm. Significantly we applied a small AC current to induce the magnetic field, so there was no heating in the coil. In addition, a double current modulation scheme was used to demonstrate that there was no zero drift and amplifier instability in the measurement. The possibility of improvement of the angular sensitivity and the potential applications are also discussed.

Original languageEnglish
Article number063112
JournalReview of Scientific Instruments
Volume82
Issue number6
DOIs
StatePublished - 06 2011
Externally publishedYes

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