Broadband strong field terahertz source based on silicon carbide single crystal

Abstract

The invention discloses a broadband strong-field terahertz source based on a silicon carbide single crystal. The broadband strong-field terahertz source comprises a femtosecond pulse laser source, a wavefront tilting system, a silicon carbide wafer and a coupling output end. The femtosecond pulse laser source part comprises a femtosecond laser and a plane mirror, the wavefront inclination system part comprises a reflection grating, a half-wave plate and a telescope imaging lens group, femtosecond laser is normally incident to a silicon carbide wafer after passing through a wavefront inclination system, terahertz pulse radiation is generated in the wafer in a light rectification mode, and the terahertz pulse radiation is transmitted to the femtosecond laser; terahertz pulse radiation is coupled and output through the triangular prism silicon prism at the coupling output end. Wherein the thickness of the silicon carbide wafer is 0.5-6 mm, the wavefront inclination angle of pulses in the wafer is 31.5-38 degrees, three cylindrical surfaces of the triangular prism silicon prism are subjected to optical polishing treatment, the cutting angle of the terahertz output surface of the triangular prism silicon prism is 31-32 degrees, and the input surface of the triangular prism silicon prism completely covers and is attached to the output surface of the silicon carbide wafer through an optical contact method.

Description

technical field [0001] The invention belongs to the technical field of nonlinear optical frequency conversion, and specifically relates to a silicon carbide wafer with different thicknesses based on the optical rectification effect and using femtosecond laser tilt pulse wave front pumping (TPFP) to realize instantaneous broadband or high-efficiency narrowband too Hertz pulse radiation, and the broadband tuning of the terahertz center frequency can be realized by changing the wavefront inclination angle, and the technical solution of effective filtering and coupling output is realized by using a triangular prism silicon prism. Background technique [0002] Based on the optical rectification effect, the use of femtosecond laser pumping nonlinear optical crystals to generate terahertz radiation pulses is a traditional way to efficiently generate terahertz radiation (Wu Xiaojun, Guo Fengwei, Ma Jinglong, et al. High-energy strong-field terahertz based on inclined wavefront techno...

AI Technical Summary

Problems solved by technology

Zinc telluride crystal has the characteristics of suitable phase matching, high nonlinear coefficient and low absorption coefficient in the low-frequency part of terahertz, and is often used in the emission end of optical rectification and the detection end of photoelectric sampling. However, its impact on terahertz The middle and high frequency bands have strong absorption, and the optical damage threshold is low, so high power density light source pumping cannot be used to further improve the conversion efficiency (Tomasino A, Parisi A, Stivala S, et al. Wideband THz time domain spectroscopy based on optical rectification and electro-optic sampling[J].ScientificReports,2013,3:3116); DAST, as a common terahertz organic crystal, has the advantages of broadband phase matching and high nonlinear coefficient, and has great potential in producing high-efficiency broadband terahertz radiation through optical rectification important application value, but it is limited by the difficult growth process, and instability factors such as deliquescence, it is difficult to obtain a reliable optical rectification terahertz light source with good robustness (Schneider A, Neis M, Stillhart M, et al. al.Generation of terahertz pulses through optical rectification in organic DAST crystals: theory and experiment[J].Journal of the Optical Society of America B,2006,23(9):1822–1835); technology, and developed a high-energy optical rectification terahertz source based on lithium niobate bulk crystals. Form cascaded difference frequency to generate terahertz radiation, because the lithium niobate crystal has a high nonlinear coefficient and a high optical damage threshold, so a photorectified terahertz source with high conversion efficiency and high energy output is obtained, however, due to Due to the limitations of phase matching and absorption characteristics, the terahertz radiation generated by optical rectification is mainly within 2THz (Zhang B, Ma Z, Ma J, et al.1.4-mJ high energy terahertz radiation from lithium niobates[J].Laser&PhotonicsReviews,2021, 15:2000295) and 14.6THz single frequency point (Jang D, Sung J H, Lee S K, etal.Generation of 0.7mJ multicycle 15THz radiation by phase-matched optical rectification in lithium niobate[J].Optics Letters,45(13):3617–3620), and usually need to place lithium niobate crystals in low temperature conditions of liquid nitrogen to reduce the absorption of terahertz radiation effect

Images