Wideband arbitrary-phase interferometer stabilization

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….]

source: © 2012 IEEE Photonics Technology Letters

(a) Schematic description of the experimental setup. ASE: amplified spontaneous emission. EDFA: erbium-doped fiber amplifier. ODL: optical delay line. FB: feedback. PZT: piezoelectric transducer. (b) Amplitude of frequency response of the PZT h^(f) . The first resonance is obtained at f=18kHz . (c) Spectrum of the signal detected by the photodiode with sine modulation at 70 kHz obtained for two values of ϕ . The first and second harmonics are marked by arrows.

A. Rosenthal, S. Kellnberger, G. Sergiadis, and V. Ntziachristos, “Wideband arbitrary-phase interferometer stabilization,” Phot. Technol. Lett. Vol. 24, pp. 1499 – 1501 (2012)