Optically controlled variable finesse Fabry-Perot interferometer

We report an optically controlled Fabry- Perot interferometer which uses a liquid crystal light valve (LCLV) for one of the mirrors. This device rotates the plane of polarization for light incident on one side through an angle dependent on the amount of write beam intensity incident on the other side. The Fabry-Perot interferometer is constructed using a polarizing cube beam splitter and a second mirror. Equations are derived showing that the finesse of this Fabry-Perot varies sharply with the rotation angle introduced by the LCLV. The dependence of this rotation angle on the incident write beam intensity varies with such controllable parameters as the frequency of the voltage applied to the LCLV, the bias voltage, and the orientation angle of the LCLV. Experimental performance is examined using a single-mode He-Ne laser beam and compares well with theoretical predictions.