Wdm Systems Research, Optical Thin Film Filter Based On Fabry - Perot Cavity

Based on the principle of thin-film Fabry-Perot filter, the dissertation is mainly focused on the study of the thin-film interleaver device and tunable filter with liquid crystal Fabry-Perot etalon, which both are used in DWDM System, as well as the thin film mux/demultiplexer utilizing the superprism effect in photonic crystal.1. Research on the interleaver based on multi-cavity thin film Fabry-Perot filter. The interleaver structure combined by Gires-Tournois (G-T) etalon and reflector was analyzed and the thin film G-T etalon with solid cavity was presented. By characteristic matrix method, the device was simulated in detailed and we disclosed that the match of the phase on reflectance is the key factor to achieve the interleaver function. Furthermore, we presented the method to design the interleaver device which is used in DWDM system by multi-cavity cascade. The novel design was discussed and the important factors that would affect the optical performance of the device were analyzed. We introduce the multi-mirror theory to analyze the relation of the reflectance of each etalon that has influence on the ripple in passband. Experimentally, the thin-film Fabry-Perot interleaver by multj-cavity cascaded was fabricated, which has 100GHz-spaced channel and the measurement system was built. The test result showed that the interleaver achieved to the bandwidth with 0.8nm@ -24dB, 0.12nm@ -0.5dB and the insertion loss nearly 0.6dB or so, which meet the requirement of the DWDM system.2. Research on the tunable filter with liquid crystal Fabry-Perot etalon. According to the principle of the output wavelength tuning by changing the thickness of Fabry-Perot etalon, the tunable filter was designed with nematic liquid crystal, which could achieve tunable filter by rotating the molecule of liquid crystal when applied the voltage. We analyzed the factors which could affect the performance of the device and discussed the "Mode Jumping" phenomenon in the measuring process of the tunable filter, studied the reason in theory and made numerical simulation, which elucidated the phenomenon properly. Our research result showed that in practice, the big difference of the refractive index of the liquid crystal material can not always increase the tunable range of the device yet; however, it should be selected suitably according to the designed parameter of the device. The influence of penetrate depth of reflective phase in dielectric reflective-mirror stack on the effective cavity length of the liquid crystal Fabry-Perot etalon was discussed and analyzed.the tuning processwas also simulated numerically. We fabricated the tunable filter with liquid crystal Fabry-Perot etalon and tested the spectrum of the sample, the result showed that the device was achieved to the tunable range from 1534.5nm to 1562.5nm and the full width of the half maximum is nearly 0.8nm in C-band. Finally, we presented a novel designed method for tunable wavelength micro-cavity organic electroluminescent diode based on the tunable feature of the liquid crystal Fabry-Perot etalon. The device was simulated numerically and proved its feasibility. The simulated result showed that the tunable range could reach to 60nm and the full width of half maximum is 5.5nm, furthermore, the device possesses good orientation in light-emission space.3. Research on thin-film mux/demultiplexer based on the superprism effect in Photonic Crystal, we designed and achieved to observe the micrometer-level shift by space dispersion in the 1D thin-film periodic structure, in the case of the thin-film stack like as Air| (HL)10|Sub, the dispersion shift of the reflective beam was detected and reached to 22μm or so.which is consisted with the designed one. The influence of the beam size on the calculation of group delay was analyzed and the condition in which the Bloch theory could be applied was also discussed. In order to enhance the intensity of the reflective beam, we made the analysis on the superprism effect of the 1D thin-film periodic structure with reflective layer...