| Similar with the bandgap of electron in semiconductor, there is a bandgap of photon in periodic dielectric structures named as photonic crystals. Photonic crystals can forbid the propagation of light in a certain frequency range and fetch great opportunities for developing important and interesting scientific and technological applications. One can design and obtain the desired photonic bandgap by changing the various parameters of photonic crystals, such as refractive index, periodicity and space filling factor, then control the propagation of light with a required wavelength. Photonic bandgap can be tuning with external stimulations including electrical field, temperature, strain and light. The realization of reversible photonics bandgap tuning is aspiration and critically important in photonic applications, such as optical switch, optical modulation and so on. As one of the simplest methods for photonics bandgap tuning, light irradiation is much easier and more convenient method for photonics bandgap tuning comparing to other ways. Up to now, many works have been reported to realize photonic bandgap tuning. However, the range of the tunable bandgap is too small and the tunable is irreversible in most reports. Therefore, it is very important to fabricate and investigate the properties of photonic crystals with large range and reversible bandgap tenability.The purpose of this thesis was to demonstrate the reversible photonic bandgap tuning of three-dimensional photonic crystals performed simply by light irradiation. Based on this, we designed and synthesized several novel arcylate compounds with azobenzene group in the subsititute (AN-azo-AO,AN-azo-AO3,AN-azo-AO6 ). The azobenzenes were introduced into the polymer networks by using two-photon induced polymerization and three-domensional photonic crystals with reversible photonic bandgap were obtained.This thesis consists of seven parts. The main point of each part is listed as following:Chapter 1: The background and fabrication, analyses the modulate mechanism of photonic crystals are reviewed. After discussed the microfabrication technology of two-photon polymerization, we addressed the purpose, significance and contents of this thesis.Chapter 2: The mechanism and factor of the photoisomerization of azobenzene derivatives were introduced and the design of azobenzene derivatives in this work was illustrated. We designed two kinds of aminoazobenzene derivatives containing amino- (Ia-Ic) and acetylamino- (IIa-IIc), respectively. And designed novel acrylate compounds with azobenzene group in the substitute (AN-azo-AO,AN-azo-AO3,AN-azo-AO6 ).Chapter 3: The photoisomerization behaviors of two series of azobenzenes in the polymer matrix (PMMA) were investigated by UV-Vis spectra. The rate constants were calculated according to dynamics equations for reversible photoisomerization. Aminoazobenzenes Ia-c exhibited faster photoisomerization and had larger integration rate constants than the corresponding acetylamino derivatives IIa-c. Azobenzenes with a longer alkyl chain (Ic, IIc) showed a faster photoisomerization rate than those with shorter chains (Ib, IIb). At equilibrium, cis ratios of IIa-c (49-60%) were higher than those of Ia-c (35%) due to larger steric limitation and intermolecular hydrogen bonding interactions between acetylamino groups.Chapter 4: This chapter included three parts. Firstly, the photoisomerization of polymer with azobenzene in the polymer network was investigated. The photoisomerization of azobenzene units occurred even they were embedded in the tightly crosslinking polymer network. The properties of the azobenzene with different acryl chain in the substitute show no significant difference. Secondly, the photonic badgap modulation was investigated. By using two-photon polymerization, the azobenzene (AN-azo-AO, AN-azo-AO3) was introduced into the polymer network and obtained two log-pile structures (PCs-1, PCs-2), respectively. The center wavelengths of these photonic bandgaps were measured as 2130 nm and 2245 nm. They showed a blue shift of ~60 nm and ~37 nm after ultraviolet light irradiating, respectively. The reversible photonic band gap tuning resulted from the photoisomerization of azobenzene. Thirdly, by using a finite-difference time domain (FDTD) with a commercial software (Rsoft FullWave), we simulated the spectra change of the photonic bandgap (PCs-1) and calculate that the refractive index of the material have a decrease of 0.114 after ultraviolet irradiation. The simulation has a good fit with the experiments.Chapter 5: A three-dimensional photonic crystals composed of woodpile structures with different periodic parameters by a two-photon polymerization technique in a novel resin containing azobenzene (AN-azo-AO) was successfully designed and fabricated. The center wavelengths of these photonic bandgaps were measured as 2151 nm and 2462 nm, with a maximum reflectivity of 9.8 % and 8.5 %, respectively. A reversible tuning of this dual photonic bandgap was achieved as a shift of 36 nm by irradiating the structures with ultraviolet light. Such a three-dimensional photonic bandgap, showing multiple photonic bandgaps with reversible tunability, could be expected to play an important role in photonic applications, such as polymeric integrated photonic circuits and multiple frequency filters.Chapter 6: The conclusions were drawn in this chapter and the future researches were discussed.Chapter 7: Experimental part including measurement and synthesis.
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