Organic-based electrically switchable Bragg gratings and their applications in photonics and telecommunications

An organic electrically switchable holographic material and its applications to display and photonics components are outlined. This material is an extension of polymer dispersed liquid crystal (PDLC) technology. Consisting of liquid crystal (LC), prepolymer and photoinitiator, a holographic PDLC (HPDLC) mixture can form LC droplets in the polymer matrix 1 - 2 orders of magnitude smaller than those in regular PDLCs. Thin HPDLC films sandwiched between transparent electrodes such as ITO-coated glass can be used to record high-resolution holographic gratings. These gratings, the result of the index modulation due to the phase separation of the LC from the polymer matrix, can be easily switched on and off under an electric voltage at a high speed 1 - 2 orders of magnitude faster than that of a regular PDLC device or a bulk nematic/cholesteric LC based device. Two types of switchable diffractive gratings, transmissive and reflective gratings, will be discussed. Applications such as wearable displays, portable projectors and optical networking components will be described in the presentation. Prototypes of some of these devices will be demonstrated in the presentation.