Tunable optoelectronic flat-top filters using coupled liquid crystal cavities

Recent developments in optical fiber communication have further opened the door to cost effective Wavelength Division Operation in metropolitan and access optical networks. To take advantage of the widened transmission window, broadly tunable optical distortionless filters must be developed to multiplex and demultiplex optical channels. Tunable optical filters are widely needed to manage channels at the optical layer in Dense Wavelength Division Multiplexing (DWDM) systems. One of the few technologies capable of such a large tuning range is liquid crystal (LC). The large anisotropy and low operational voltage make it an ideal candidate for low cost tunable optical filters.;The objective of this dissertation is to present flat-top/distortionless tunable filters that provide the channel shape requirements for DWDM systems channel management. This dissertation introduces two novel types of LC based tunable filters: the tunable LC coupled Fabry-Perot filters (TLCCFP-F) and the LC tunable optical interleavers. Although many studies of the tunable LC Fabry-Perot filters have been presented using different configurations, these efforts fail to address the requisite channel shape requirements for distortionless transmission. Recently, tunable optical interleavers based on electro-optic crystals to gain tuning capability, have greatly attracted attention. These interleavers have the channel flat top and minimal ripple. This approach has the disadvantages of high operational voltage requirements and design complexity.;Several configurations of the TLCCFP-F were investigated in order to achieve a tunable filter with flat-top performance across the C and L bands with a passband ripple less than 0.008 dB, and broad overall tuning range of 175 nm. TLCCFP-F have comparable or better performance than the commercial 100 GHz fixed single channel filters. The optical interleaver filters, based on the combined Michelson interferometer (MI) and the Gires-Tournois interferometer (GTI), show a flat-top performance. Integrating the LC tuning capability into the interleaver has the advantages of low operation voltage requirements and design simplicity. Therefore, the LC tunable optical interleavers have a flat-top response and tunable center wavelength.;Numerical simulations were performed to estimate performance tolerance for both filters. The analysis shows that these structures are feasible with current fabrication techniques. A detailed fabrication process for the TLCCFP-F was proposed. The LC tunable optical interleaver was fabricated and tested. Some results show the tuning capability of the interleaver.