Adjustable phase control in stabilized interferometry

Abstract

We report an optoelectronic feedback loop that permits the active stabilization of an interferometric setup for any chosen value of the phase between the interfering beams. This method is based on phase modulation and homodyne detection techniques. The phase can be stabilized with a precision of better than 1 deg for our experimental conditions.

Stabilized photorefractive running holograms, with arbitrarily selected phase shift, for material characterization

“…The bulk absorption of the crystal at the operating wavelength was α ≈ 10.50 cm −1 . The recording was carried out using self-stabilization with an arbitrarily selected phase shift ϕ as described elsewhere [21,22].…”

“…Such feedback controlled running holograms under strong light absorption were used for material characterization too [19,20]. The use of a feedback setup enabling stabilized recording with arbitrarily selected holographic phase shift ϕ (the phase shift between the transmitted and diffracted beams along the same direction behind the crystal) was shown [21] to produce photorefractive running holograms with controlled speed and diffraction efficiency. In this way almost environmental perturbation-free (stabilized) running holograms with known and fixed phase shift values could be produced [22] and used for photorefractive materials characterization [23].…”

Oscillating holograms recorded in photorefractive crystals by a frequency detuned feedback loop

“…[16][17][18][19][20][21][22][23][24][25] Stabilization of a holographic setup using a photorefractive crystal in a two-wave mixing experiment was first proposed by Kamshilin et al 16 The method is based on the active control of the phase shift between the transmitted and diffracted beams that propagate along one of the crystal output directions. Phase is linked to the holographic phase shit between the interference pattern and the refractive index modulation; for a pure index grating and in cases where self-diffraction effects can be neglected, = Ϯ / 2.…”

“…Developments and/or improvements on different aspects of the technique extended its application to = Ϯ / 2, 17 and later to any arbitrary value. 18 By using these techniques, phase-locked photorefractive waves moving at constant velocities have been generated in different applications. [28][29][30] In a recent paper, Bryushinin and Sokolov 31 presented an optoelectronic feedback loop suitable for generating photorefractive wave oscillations.…”

“…The technique uses some ideas reported in Refs. [16][17][18] and introduces a quasisynchronous demodulation scheme to create a voltage-controlled phase term into the extracted error signal. This is done through a voltage waveform from a function generator and an electronic time delay circuit, which shift the frequency of the reference wave used for signal demodulation.…”