Fig. 1. Polarization rotation measurement system using Faraday modulator. P, polarizer; FM, Faraday modulator; C, rotation generating cell; A, analyzer; PD, photodetector; LIA, lock-in amplifier.

Fig. 2. Schematic of the Faraday modulation-based polarization rotation measurement setup using differential detection. P, polarizer; FM, Faraday modulator; NPBS, non-polarizing beam splitter; M, mirror; C, rotation generating cell; A1, A2, analyzers; PD1, PD2, photodetectors; LIA, lock-in amplifier; OSC, oscilloscope.

Fig. 3. Variation in the axial magnetic field of the solenoid coil of the Faraday modulator.

Fig. 4. Measurement of the Verdet constant of TGG magneto-optic glass using the differential measurement system.

Fig. 5. Noise spectra for a small polarization rotation angle using two measurement techniques. The black and red curves correspond to the single beam detection and the optical differential detection, respectively. The low-frequency performance was considerably improved with the optical differential detection method.