Research On Measurement Technology And Application Based On Optical Properties Of Crystal

Photonic crystals, including electric-optical crystal, phonon-optical crystal, magneto-optical crystal, laser crystal, nonlinear crystal, photorefractive crystal and scintillation crystal had been studied intensively for their promising potential for application. Whereas the optical property is the key feature that is looked for, research on basic optical measurements and application test is necessary and important.The present paper will be focusing the study of photorefractive crystal (Ca0.28Ba0.72)x(Sr0.60Ba0.40)1-xNb2O6(CSBN), which has a Tungsten Bronze (TB) structure. Both theoretical and experimental studies were conducted on the absorption spectroscopy of CSBN in an applied electric field given varies Ca doping rate. Doping-dependent absorption spectroscopy data was obtained and analyzed. In addition, conoscopic interference together with digital image analysis was used to study the double-axis angle of Nd:LaVO4. Auto-measurement and auto-correction was achieved by a software program written by the author. Self-pumped phase conjugation was also studied on CSBN. In the paper, detailed research will include:1. Based on previous research that, for CSBN, the absorption in an applied electric field is mainly affected by temperature, the absorption coefficient should be proportional to the square of electric field intensity. Absorption of CSBN50and CSBN75crystals in an electric field range of0Kv/cm-2.1Kv/cm was studied. It is found that, instead of linear relation, the actual relation is oscillatory and the absorption is doping dependent. Together with additional experiments, it is confirmed that the electric field is more important in this case compared with thermal excitation. This phenomenon was analyzed in the perspective of structure. We propose that the oscillatory nature of doping-dependence result from spatial charge relocation upon applied field. Finally, the effect of external field on absorption coefficient and absorption length was analyzed. It is possible that based on the computation result, external field has larger effect on absorption coefficient than absorption length. As a conclusion, we demonstrated that applied external field is an effective way to study and understand the absorption spectroscopy, which is also an important application of the present research.2.Current double-axis measurements and angle detection techniques are largely based on x-ray diffraction. which is complex and high-maintenance. Inspired by conoscopic interference, the authors proposed that conoscopic interference pattern can be used to measure double-axis angle. Mathematical calculation was first conducted to establish the conoscopic interference pattern of double-axis crystal, based on which experiments was successfully conducted on the measurement of double-axis angle of laser-crystal Nd:LaVO4. The angle was determined to be60°with an error bar smaller than0.5°. The author utilized C++builder to program and managed to achieve data auto-collecting, auto-determination of optical axis, data analysis and uncertainty analysis on a single platform. This program can provide sufficient support in many application cases where high resolution is not needed.3. We summarize the theoretical foundation of the optical phase conjugation, introduce the mathematical description of phase conjugate wave, four-wave mixing effect and the generation of phase conjugate wave, describe the induction light scattering and fan effect, summarizes the main four kinds of self pumped phase conjugate theory model.We set the self pumped phase conjugate experimental light path, and has carried on the corresponding experiment using the CSBN crystal. We mainly observe and record when part of the light occurs self pumped phase conjugate phenomenon, transmission light behind the crystal has strange changes, and we give the theoretical explanation. We think it occurs because the self pumped phase conjugate of light and part of reflected light and transmitted light are modulated by the refractive index grating produced by self pumped phase conjugate. We also discuss the application of self pumped phase conjugate in image processing in this paper, and have got good experimental results. We considered the strengthening of Laplace factors in the self pumped phase conjugate wave lead to the emergence of image edge enhancement effect.