Photonic Crystal Autocollimation Characteristics And Its Application In Laser Radar

As the semiconductor integration closes to the limit more and more, the applicationof photonic crystals in a new generation of optical communication systems is moreurgent in need. Its superior performance and special dispersion characteristics provide anew way to control the propagation of light and electromagnetic waves in a small scale,making possible to effectively meet the demands of miniaturization and integration.The self-collimation effect of photonic crystals is found and studied in recent years.In this paper, proceeding from the basic theory of photonic crystal, a new type oftwo-dimensional photonic crystal devices based on self-collimation effect is presentedand designed after the analysis of simulation. Meanwhile, the total reflection mirror andthe collimator constrained structure are introduced in the laser radar system, which notonly achieves filtering and collimation constraints but also provides a new design ideafor the development and application of optical communications of such devices infuture.The main contents of the paper are as follows:1. The study begins with the group velocity, analyses three kinds of special effects inphotonic crystals, including the negative refraction effect, self-collimation effect andsuper prism effect, are analyzed and discussed. The direction of the group velocity isperpendicular to the equal frequency line (surface),when the frequency line (surface) isflat, because of the group velocity in the same direction, the beam can propagateaccording to its self-collimation.2. Three numerical calculation methods of the photonic crystals are derived,including the transfer matrix method, the plane wave expansion method and the finitedifference time domain method. Furthermore, their advantages, disadvantages andapplication scope are introduced respectively.3. The band gap characteristics of the photonic crystal are discussed and theinfluence of lattice structure, filling ratio and permittivity on the several commonphotonic crystal band gap have been researched, which lay the foundation for the next step to optimize the self-collimated transmission characteristics of the photonic crystalby changing the parameters, such as filling ratio and permittivity.4. The theoretical analysis of the collimation effect of photonic crystal is made andthe transfer process is simulated with the FDTD method; the influences of three factors,including the incident beam width, the crystal structure width, and random error, on theautocollimator transmission are analyzed.5. The total reflection mirror and collimating devices are designed on the basis ofthe analysis of self-collimation, which can be applied to the three-dimensional imaginglaser radar and meet the demands of miniaturization and integration.