source: © 2012 IEEE Photonics Technology Letters
We report on a robust scheme for wideband variable-phase interferometer stabilization based on active modulation. In contrast to previous schemes, the correction signal is generated without using second harmonics, whose low amplitude often requires employing narrowband lock-in amplifiers. Resonances in the element modulating the phase are attenuated to enable high gain without high-frequency oscillations. Operation over a 3-kHz bandwidth is demonstrated.  [Read more…]
Fig. 2 (a) Schematic description of the analog feedback circuit. PS: phase shifter. BSF: band-stop filter. HPF: high-pass filter. FB: feedback. (b) Measured combined response of the electronic filter and optical system. The figure shows a decrease in the strength of the PZT resonance.