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 Ď• . The first and second harmonics are marked by arrows.