Photorefractive Polymers with Superior Performance
N. Peyghambarian, M. Eralp, S. Tay, G. Li, J. Thomas, A. Schulzgen, S. Marder, M. Yamamoto and R. Norwood
We report on development of photorefractive materials with superior performance. High-voltage (5-10 kV) poling necessary for the operation of photorefractive polymeric devices has been a drawback of these materials. We have now developed devices that can be poled at order of magnitude lower voltages by carefully engineering the material composition using high performance nonlinear chromophores for thinner devices. For a thickness of 20 µm, the device showed more than 90% diffraction efficiency with a dominant fast response time of 27 ms at about an applied voltage of 1 kV. A useful diffraction efficiency of about 10% can be observed even at a voltage as little as 450 V, which demonstrates a major step forward in the possible applications of photorefractive devices. We have also been able to extend the operating wavelength to near IR. By employing a new sensitizer dye, we have demonstrated a first-time proof of photorefractivity at 975 nm in an all-organic composite with 90% diffraction efficiency and video rate response time using a low power cw laser. This is a significant advance in the development of all-organic PR device for near-infrared imaging and optical communication. Furthermore, devices were made to operate at 1550 nm wavelength, suitable for fiber optics applications. Using two-photon absorption (TPA) processes, we demonstrated more than 40% diffraction efficiency maintaining near video-rate response time. This approach provides the inherent advantage of non-destructive read-out using cw laser light. As an application of these devices, we demonstrated beam cleanup and aberration correction in a free space communication application. An oil-filled phase plate, which generates atmospheric-like wavefront aberrations, was employed and demonstrated high quality aberration corrections.