Study On Fabrication Method Of (2+1)-dimensional Photonic Lattice

Photonic crystal has very wide application foreground in optical communications and integration optics. Array wave-guides is the extremely format of (2+1)-dimensional photonic lattices. It can be applied to control the light-transmitting path, control optics interlinkage and study the transmitting action of light in photonic crystal, etc.At present, there are many studys on fabricating methods of wave-guide arrays, but most of the techniques are very complex. All optical method is a kind of the simplest, most convenient and most feasible method to fabricate wave-guide arrays in the photorefractive crystal. With the development of real-time fabricating wave-guide arrays using light induced technology, it improves the conventional techniques of wave-guide arrays fabrications, it makes fabricating (2+1)-dimensional photonic lattices even more real-time, therefore, the study on the transmitting action of light in photonic crystal become even easier. At present, the study on discrete diffraction and discrete soliton in (2+1)-dimensional photonic lattices becomes the research focus of nonlinear optics. Fabricating wave-guide arrays by light induced technology in self-focus photorefractive crystal is easier, but it is not easy to preserve photonic lattices, moreover, the materials are expensive. So the most important basal research problems for fabricating needful photonic lattices in the field of nonlinear optics are the study on the mechanism of fabricating wave-guide arrays using array beam of light, the study on interaction of array beam of light with photonic lattices fabricated in self-defocus photorefractive crystal and the study on fabricating needful photonic lattices.In the work of this thesis, using YAG laser and He-Ne laser as the light source, which output wavelength are 532nm and 632.8nm, we successfully real-time fabricate various periodic (2+1)-dimensional nonlinear photonic lattices in the self-defocus photorefractive crystal LiNbO3: Fe of different thickness by diverse light induced methods that include the method of optical Fourier transform, the method of imaging and the method of interference. The experimental result shows that using the method of optical Fourier transform, the short periods wave-guide arrays can be fabricated by controlling irradiation time, but the area of wave-guide arrays fabricated is smaller. Using the method of interference, one-dimensional wave-guide arrays can be fabricated easily, but the light-pathway of fabricating two-dimensional wave-guide arrays is more complex. Using the method of imaging fabricating photonic lattices, the lattices periods are bigger and the writing time is longer though the defect modes are imported easily in photonic lattices. But once the good quality amplitude mask is fabricated, the photonic lattices can be fabricated generally, but also the photonic lattices that contain corresponding defect modes can be fabricated by choosing suitable amplitude mask.In the process of fabricating photonic lattices and studying the transmiting action of light in photonic crystal, for the first time we observe a phenomenon of spacial frequency doubling. Using the method of optical Fourier transform and interference fabricate photonic lattices in self-defocus photorefractive crystal LNbO3:Fe, We first find the new experiment phenomenon that dual-beam interference fringes are divided into two each, and four-beam interference fringes are divided into four each. We carefully study this phenomenon and prove that it is a phenomenon of spacial frequency doubling. This phenomenon is the result of the interaction between the entrance array beam and the fabricated photonic lattices. It can be explained tentatively by the theory of phase transfer and phase abruption, and it is the important representation of nonlinear character of photorefractive photonic lattices. We analyze its physical mechanism and think the interaction between the entrance array beam and the fabricated photonic lattices can even produce spacial high-order harmonics besides spacial second-harmonic. Using this character, spacial frequency-doubling photonic lattices and spacial frequency high photonic lattices can be fabricated. The discovery of this character is very significant for the fabrication of photorefractive photonic lattices and optical micro-structure, and it is helpful to study the mechanism of fabricating the wave-guide array and optical micro-structure in self-defocus photorefractive crystal by array light beam and the interaction between the array light beam and fabricated photonic lattices.Base on the fabrication of nonlinear photonic lattices using the method of optical Fourier transform, we observe the discrete diffraction phenomena of different photonic lattices. In the experiment, besides common discrete diffraction, we also find a new discrete diffraction phenomenon, and make some basic analysis about it. In addition, we study discrete soliton generation after importing defect mode preliminarily.