Adaptive interferometers with no external field using reflection gratings in CdTe:Ge at 1550Â nm

We demonstrate experimentally the operation of an adaptive two-wave mixing interferometer with no field applied to a photorefractive crystal in which the quadrature condition is introduced by an external π/2 phase step. To achieve high signal to noise ratio the counter-propagating geometry for grating recording is used with a CdTe:Ge crystal, ensuring effective recording of reflection holograms. It is demonstrated that the interferometer with a photorefractive semiconductor crystal provides good sensitivity without the adverse effects that are normally associated with an applied field.