Researches On The Preparation And Characterization Of Photorefractive Photonic Microstructures

Photonic microstructure is a kind of excellent photonics materials. It has an attractive prospect in the manipulation of photons movements. This provides new possibilities for the development of photonics devices in all-optical communications. Mature and perfect fabrication technologies of microstructures are conducive to the intensive research and practical application of photonic microstructures. However, traditional methods of fabricating photonic microstructures usually have certain limitations, such as, equipment complexity, difficult to be fabricated, the structure style is single, flexibility is poor, and production efficiency is low, expensive, and not suitable for mass production. The optical induction technique is a new method for fabricating photonic microstructures developed in recent years. It mainly uses the light-induced refractive index changes characteristics of photorefractive media. The refractive index microstructures formed by modulating the spatial intensity distribution of the incident light. The optical induction technique has some advantages, such as, simple, flexible, low cost, easy to implement, materials can be recycled. At present, most of researches on fabricating photonic microstructures by optical induction technique are about periodic microstructures, meanwhile, most of them present the fabrication area is small and efficiency is low. The relevant research about aperiodic complex photonic microstructures (such as, quasicrystal lattices and composite periodic lattices) progress slowly because of fabricating difficulty. Aimed at these issues, this paper conducted deep and systematic research about optical fabrication of various photonic microstructures in iron-doped lithium niobate photorefractive crystal based on optical induction technique. The main findings are as follows:1. Develop a simple and low-priced experimental device, which achieves optional multi-beam interference by combining multi-pinhole plates and Fourier transform lens. This new device overcomes the shortage of traditional multi-beam interference devices, complicate, hard to adjust, and hard to achieve. It also has flexible expandability. Two- and three-dimensional photonic quasicrystal microstructures are optically induced inside an iron-doped lithium niobate photorefractive crystal for the first time. Optically induced quasicrystal microstructures are also verified and represented by plane wave guiding, Brillouin-zone spectroscopy and far field diffraction pattern imaging.2. Aimed at small made area and low efficiency issue, propose two experimental approaches for fabricating large-area two-dimensional photonic microstructures in photorefractive crystal, multi-lens board and multi-face wedge prism. Both of approaches are easy, no need to complicate adjusting advice, stable, low cost, and high efficiency. Fabricating large-area two-dimensional periodic photonic microstructures and quasicrystal microstructures in iron-doped lithium niobate crystal, increase the fabrication efficiency greatly. Verify and analyze several experimental approaches to fabricate large-area photonic microstructures. Both multi-lens board and multi-face wedge prism have good expandability. They can produce kinds of more complex large-area photonic microstructures with proper design.3. The complex type photonic microstructures are fabricated in lithium niobate crystal for the first time. Composite periodic lattice microstructures, wavy lattice microstructures and different defects microstructures are fabricated by using multi-beam interference and projection imaging method. This work successfully solves hard to make defect and hard to achieve arbitrary shape photonic microstructures problem in traditional methods of fabricating photonic microstructures. Both of these producing methods have easy-operate and good expandability advantage. These complex type photonic microstructures provide a good experiment media for research on the nonlinear optical properties of photonics micro-cavity and microstructure waveguides. What’s more, it has an excellent future application in integrated optics and microstructure optical waveguide devices fields.4. Photorefractive photonic microstructures are conducted quantitative analysis using Bragg diffraction phenomenon. Induced large-area two-dimensional square lattice microstructures are set as an experimental object and analyze by Bragg diffraction measuring. By means of detecting normal incidence and lateral incidence, measure the lattice spacing of microstructures, which draw the same conclusion with the theoretical prediction. Bragg diffraction characteristic measuring leads us a new way to quantitatively analyze photonic microstructures. This finding is helpful to do deeper research characters of photonic microstructures, to promote relevant development and application on microstructure photonic devices.