In recent years, laser technology has achieved rapid development. The data shows that the annual growth rate of China's laser pointer industry reached more than 20%. Under catalysis, the laser industry will continue to maintain rapid development. As a key device in the industry chain, the development of lasers has always been the top priority of the industry. Due to the very limited wavelength of lasers that can be emitted by traditional laser crystals, it is impossible for current laser products to produce lasers of arbitrary wavelengths. In the application of laser technology, people often need to obtain a variety of lasers with different wavelengths and spectral widths to solve the practical needs; while traditional laser crystals cannot help the laser to achieve this demand. How to overcome the intrinsic defects that traditional laser crystals are difficult to overcome and expand the development of solid-state laser technology and laser source equipment have long been the subject of active research by scientific research institutions around the world.
In many frontier scientific research. Solve for any wavelength. As well as the broader spectrum of ultra-continuous, ultra-wideband, laser light sources with excellent characteristics in terms of temporal coherence and spatial coherence, the significance is significant. If this problem can be solved, and can enter the commercial production and application process, it will open a new door for the laser industry, and subvert or enhance the application of laser technology in many fields, and derive more new applications.
The characteristics of the green laser pointer produced by the laser depends on the laser crystal. As another important part of the laser system, the nonlinear crystal can generate a variety of new laser spectrum lines through the nonlinear interaction with the laser, thereby expanding the frequency window of the laser. Obtaining research on new nonlinear superlattices and nonlinear photonic crystals has become a very effective means to overcome the above-mentioned problems. The matching quasi-phase matching theory was proposed by J. Berger and others in 1962 until the birth of the concept of nonlinear photonic crystals in 1998. Limited by production process and theoretical method. In reality, people still cannot perfectly combine the quasi-phase matching theory with the growing practical requirements. Produce all kinds of high-performance nonlinear superlattices and nonlinear photonic crystals.