Lithium Niobate Thin Film Based Novel Geometric Electro-Optic Modulator

Rainbow Communications proposes to investigate a compact, highly efficient, low driving voltage, broad bandwidth, high extinction ratio, low optical insertion loss, zero frequency chirp, electro-optic modulator based on thin-film lithium niobate materials, selected domain inversion technique, and optical-wave and electrical-wave velocity matched traveling-wave electrodes configuration for applications in RF photonic links and optical communication. The proposed EO modulator will be capable of modulating the intensity of optical light up to 40GHz with sub-volt driving voltage and up to 20-dB extinction ratio. The total fiber-to-fiber insertion is as low as 3-dB with zero frequency chirp. Several unique features distinguish it. First, Rainbow will fabricate a Mach-Zehnder (MZ) interferometer waveguide structure on a thin-film LiNbO3 material. Second, the domain of one arm of MZ will be inverted by using Rainbow¡¯s unique electrical poling process. Third, by using thin-film structure and optimized traveling-wave electrode design, this EO modulator can achieve both very broad bandwidth, over 40GHz and very low driving voltage, much less than 1-V with high extinction ratio. Fourth, by using Rainbow¡¯s novel package design and optical-fiber to waveguide coupling optimization, overall optical loss is very low and the efficiency of proposed EO modulator can be reach very high.