Study On The Mechanism And Characteristics Of Guided-mode Resonance Subwavelength Device

Guided-mode resonance (GMR) filter is of great interest recently for itsoutstanding advantages such as narrowband of few nanometers, high efficiency, lowsidebands extended over a large spectral range, simple structures and so on. Opticaldevices such as of optical filters, polarization separators with superior performancescan be designed utilizing the guided-mode resonance effect, which can advance thedevelopment of optical communications and related optical areas. The design andexperimental result of GMR filters with the characteristics of filter and highreflectance are presented in this dissertation.Visible band guided-mode resonancefilter with the resonance wavelength at693nm is fabriciated which is based onholographic technique. Moreover, kinds of tunable guided-mode resonace filter arepresented. And the application prospect of guided-mode resonace filter is alsodiscussed.In this dissertation, the rigorous diffractive theory is presented firstly. A generaldiffraction analysis of rectangular grating with different polarizations is introducedby the method of the rigorous coupled-wave ananlysis (RCWA). Based on theresonance anomalous phenomenon occurred in the subwavelength waveguide grating,the effects on the filter characteristics with different structure parameters wasanalyzed which shows that the GMR filter with ideal filter characteristics can bedesigned by adjusting those parameters. It could be found that the thin-film layerunder the grating layer can be used to control the spectrum response curve of thedouble layer GMR filter with RCWA.The contoral could be used to reduce thefabraction difficulties at least in two aspects. First, we can adjust the thickness of thethin-film layer under the grating layer to decrease the depth of the grating groovewithout changing the filter characteristics during the design process. In this way, thefabraction difficulty which is arised by the deep groove grating can be solved.Furthermore, the deviation caused by overetching during the fabrication process willlead to the deviation of the resonant wavelength. To compensate this deviating, theway of covering one compensatory layer film with certain thickness and refractiveindex on the surface of the GMR filter is investigated. Simulation results show thatthe deviation is compensated perfectly by this way, which means that it can be usedto reduce requirements of precision to the grating period and the groove depth bycontrolling the thin-film layer under the grating laye during the fabrication process. As the applications of GMR devices in optical communications, security, tunablelaser and so on are widely concerned, several kinds of the tunable GMR filters withnarrow-bands and high-reflectances were presented based on the rigorouscoupled-wave theory. With the analysis of the variation azimuthal angles influence tothe GMR flter, a kind of tunable narrow band GMR filter designed by tuning theazimuthal angles is illustrated. Combined the electro-optical property of polymerdispersed liquid crystal (PDLC) with the GMR property, a kind of tunable GMRfilter based on PDLC is designed by electronically controlling the refractive index ofPDLC. The resonance wavelength can be tuned from672.4nm to698.4nm, whichachieved a tunable wavelength range of up to26nm. In addition, the concept anddesign of the spectrum energy tunable GMR filter is put forward for the first time.With a specific structure of GMR filter, the energy of the reflectance spectrum can betuned in the dual channels by tuning the azimuthal angles.The spectrum energytunable GMR filter can accurate control the energy of the reflectance spectrum whichmay have potential application in the biologica area. The paper utilizes the array toproduce colored images that changes the traditional color ink colored image concept.Those guided mode resonant gratings are fabricated with the same structure butdifferent period to filter light into the needed for red, green and blue that served asthe three primary colors to display images. Because of the excellent characteristics ofguided mode resonant grating such as simple structure, high diffraction efficiencyand narrowband, monochromatic light of the three primary colors with high puritycan be easily achieved. Colored image can be obtained by arranged and distributedthose microstructure gratings. Preliminary simulation results show that the originalimage can be reproduced realistic with the TE polarized incident light. Owing withthe advantages of resources saving, environmental protection,the method of coloredimage reproduction has the potential for industrial production and application inmany fields,such as the printing industry、authentic preservation and light display.GMR metamaterial structure with the resonance occuring during2and18GHzin the microwave band was given according to the RCWA and design method ofGMR filter. The transmission cut off in the9.7GHz, while the transmission farawayfrom the cut-off zone exceeding90%over the2and18GHz. In addition, thestructures of the double layer subwavelength GMR filter with the resonancesoccurring in the same resonance wavelength were designed by using different refractive index material of HfO2and Ta2O5. The fabrication processe andtechnology of the subwavelength visible band GMR filter with the resonancewavelngthe at693nm were investigated based on the fabrication process of thesubwavelength grating. The filter characteristics of the GMR filter was tested anderror analysis.