We investigate the fabrication of holographic polymer dispersed liquid crystals (H-PDLCs) for use as switchable laser cavities. H-PDLCs are liquid crystal and polymer dispersions used in grating applications for displays, optical communications and optical security. By controlling the pitch of the H-PDLC and the laser dye used, we are able to fabricate a tunable laser. H-PDLCs were made in both reflection and transmission modes to vary the method by which lasing action occurs. The dye-doped H-PDLCs were pumped with nanosecond pulses from a laser with emission at 532 nm and a power of approximately 6 mJ. Lasing action was observed using a spectrometer from the H-PDLC grating; peak wavelengths occurred over a range of wavelengths, depending on the dye used, with the full width of the emission peaks approximately 6-8 nm at half maximum. The lasing action can be turned on and off by the application and removal
of an electric field due to the properties of an H-PDLC. Furthermore, we investigate multidimensional architectures and quasicrystal symmetries for lasing applications. Applications for these cells include use in small-scale portable devices requiring a tunable laser source.
We propose a novel switchable circular-to-point converter (SCPC) device based on the holographic polymer dispersed liquid crystal (HPDLC) technology. An SCPC device converts the Fabry-Perot ring pattern into one point or point array, while an external electrical field on the SCPC will deactivate the conversion. By designing an Indium Tin Oxide (ITO) ring-pixel pattern on the SCPC that match the Fabry-Perot circular interference pattern, we are free to select different single rings of Fabry-Perot ring pattern and convert it into different points that is easy to be detected or collected. Stacking different single SCPC elements will give us a random Optical Switch with application in Lidar detection and optical telecommunication.
Scientific Solutions Inc. (SSI) has developed a tunable liquid crystal Fabry-Perot (LCFP) etalon system comprised of a resolving and a suppression etalon in tandem. The 30-micron resonant cavity spacing of the resolving etalon provides for high spectral resolution while the system maintains the significantly broader free spectral range of the 6-micron gap suppression etalon across the tunable region. An applied electric field alters the ordinary refractive index of nematic liquid crystal cells within each etalon cavity, thereby
altering the resonant properties of the etalons, allowing for system tunability over several orders of interference. This system acts as a tunable optical filter with an operating range from 700nm to 1100nm.
Testing of the LCFP etalon system with both a high resolution Czerny-Turner monochrometer and a stabilized ND:Yag laser demonstrate a FWHM of 0.67nm to 1.03nm. System transmission reaching 70% of polarized light is achieved with tunability over one free spectral range in approximately 30 milliseconds. The free spectral range of the tandem etalon system ranges from 27nm-36nm over the operating range, and
allows for 40 randomly selectable spectral channels per free spectral range. This system is designed for use in spectral imaging systems, initially for the semiconductor industry, but is equally applicable to the earth remote sensing community.
We propose new tunable liquid crystal Fabry-Perot filters for fiber-optical telecommunication application. The filters have a low insertion loss, fast response time, wide tunable range to cover total c-band, or L-band, or both. They are solid-state filters without moving parts and the tuning voltages are low.