Polarisation Conversion at Cryogenic Temperatures

This video shows the response of an electro-optic polarisation converter as a function of operating temperature, when cooled from 300K to 0.8K over a duration of 16h. Linearly polarised light is sent through the sample and changes in the intensity of the ordinary and extra-ordinary polarised beams are monitored, dependent on an applied voltage. During the cool down, the wavelength and modulation voltage is continuously swept, around the (temperature dependent) phase-matched wavelength and +/- 27V, respectively. The operation wavelength shifts to longer wavelengths because of the temperature dependent refractive index of the material.