We demonstrate a common-mode rejection scheme for a bulk-optic triangu
lar Faraday current sensor that can eliminate optical noise induced by
fiber-link vibration. The noise floor before applying common rejectio
n was about 30 dB for a 100 Angstrom Faraday signal and transceiver vi
bration levels of approximately 30 g. This was reduced to about 60 dB
for the same vibration levels. The sensor's exploitation of Ampere's c
ircuital law is also demonstrated.