Application of SiC

SiC crystal is an important wide-bandgap semiconductor material. Because of its high thermal conductivity, high electron drift rate, high breakdown field strength and stable physical and chemical properties, it is widely used in high temperature, In high frequency and high power electronic devices. There are more than 200 types of SiC crystals that have been discovered so far. Among them, 4H- and 6H-SiC crystals have been commercially supplied. They all belong to the 6mm point group and have a second-order nonlinear optical effect. Semi-insulating SiC crystals are visible and medium. The infrared band has a higher transmittance. Therefore, optoelectronic devices based on SiC crystals are very suitable for applications in extreme environments such as high temperature and high pressure. Semi-insulating 4H-SiC crystal has been proved to be a new type of mid-infrared nonlinear optical crystal. Compared with commonly used mid-infrared nonlinear optical crystals, SiC crystal has a wide band gap (3.2eV) due to the crystal. , High thermal conductivity (490W/m·K) and large bond energy (5eV) between Si-C, so that SiC crystal has a high laser damage threshold. Therefore, semi-insulating 4H-SiC crystal as a nonlinear frequency conversion crystal has obvious advantages in outputting high-power mid-infrared laser. Thus, in the field of high-power lasers, SiC crystal is a nonlinear optical crystal with broad application prospects. However, the current research based on the nonlinear properties of SiC crystals and related applications is not yet complete. This work takes the nonlinear optical properties of 4H- and 6H-SiC crystals as the main research content, and aims to solve some basic problems of SiC crystals in terms of nonlinear optical properties, so as to promote the application of SiC crystals in the field of nonlinear optics. A series of related work has been carried out theoretically and experimentally, and the main research results are as follows: First, the basic nonlinear optical properties of SiC crystals are studied. The variable temperature refraction of 4H- and 6H-SiC crystals in the visible and mid-infrared bands (404.7nm～2325.4nm) was tested, and the Sellmier equation of variable temperature refractive index was fitted. The single oscillator model theory was used to calculate the dispersion of the thermo-optical coefficient. A theoretical explanation is given; the influence of the thermo-optic effect on the phase matching of 4H- and 6H-SiC crystals is studied. The results show that the phase matching of 4H-SiC crystals is not affected by temperature, while 6H-SiC crystals still cannot achieve temperature phase matching. condition. In addition, the frequency doubling factor of semi-insulating 4H-SiC crystal was tested by the Maker fringe method. Second, the femtosecond optical parameter generation and amplification performance of 4H-SiC crystal is studied. The phase matching, group velocity matching, best non-collinear angle and best crystal length of 4H-SiC crystal pumped by 800nm ​​femtosecond laser are theoretically analyzed. Using the femtosecond laser with a wavelength of 800nm ​​output by the Ti:Sapphire laser as the pump source, using two-stage optical parametric amplification technology, using a 3.1mm thick semi-insulating 4H-SiC crystal as a nonlinear optical crystal, under 90° phase matching, For the first time, a mid-infrared laser with a center wavelength of 3750nm, a single pulse energy up to 17μJ, and a pulse width of 70fs was obtained experimentally. The 532nm femtosecond laser is used as the pump light, and the SiC crystal is 90° phase-matched to generate signal light with an output center wavelength of 603nm through optical parameters. Third, the spectral broadening performance of semi-insulating 4H-SiC crystal as a nonlinear optical medium is studied. The experimental results show that the half-maximum width of the broadened spectrum increases with the crystal length and the laser power density incident on the crystal. The linear increase can be explained by the principle of self-phase modulation, which is mainly caused by the difference of the refractive index of the crystal with the intensity of the incident light. At the same time, it is analyzed that in the femtosecond time scale, the nonlinear refractive index of SiC crystal may be mainly attributed to the bound electrons in the crystal and the free electrons in the conduction band; and the z-scan technology is used to preliminarily study the SiC crystal under 532nm laser. Non-linear absorption and non

linear refractive index performance.

6 inch High-purity Semi-insulating 4H-SiC Substrates Specifications