Advances in photorefractive polymers and applications

Photorefractive (PR) polymers change their index of refraction upon illumination through a series of electronic phenomena that makes these materials one of the most complex organic systems known. The refractive index change is dynamic and fully reversible, making PR materials very interesting for a large variety of applications such as holography and 3D display. In order to improve the recording speed and achieve videorate for our stereographic display application, we have introduced a new type of electrode geometry where the anode and cathode are in the same plane and are shaped as interpenetrating combs. This type of electrode geometry does not require the sample to be tilted with respect to the writing beams to record the hologram, which is a significant advantage. To monitor the highly non-homogeneous field resulting from this configuration, we used a multiphoton microscope to directly observe the chromophore orientation in situ upon the application of an electric field. Most recently, we developed a fast repetition rate laser (10kHz) where the pulse width can be adjusted from microseconds to milliseconds so that, in conjunction with a ns Q-switched Nd:YAG laser and an externally chopped CW laser, the diffraction efficiency of the material could be measured over 9 orders of magnitude. This measurement helps us better understand the mechanism of grating buildup inside photorefractive polymers.