Two-tone femtosecond laser collinear pumping detecting thermal reflection system

Abstract

The invention relates to a two-tone femtosecond laser collinear pumping detecting thermal reflection system which comprises a polarization output pulse laser, a wave plate, a beam splitting element, a reflecting mirror, an electro-optical modulator, a frequency doubling crystal, an optical filter, a beam expander, an electronic control displacing platform, a cold-light mirror, a fixing adjusting frame, a focusing lens, a photoelectric detector and a filter amplifier, wherein the polarization output pulse laser is used for outputting a pulse laser; the wave plate is used for causing the laser to rotate along a polarization direction; the laser beam is divided into two mutually vertical beams along the polarization direction by the beam splitting element; the laser beam is received and reflected by the reflecting mirror; the laser beam is modulated by the electro-optical modulator; the frequency doubling crystal is used for causing the laser to generate second harmonics; the laser within an appointed wavelength interval is filtered by the optical filter; the diameter of the laser beam is expanded by the beam expander; the electronic control displacing platform can move back and forth; the laser beams with different wavelengths are combined by the cold-light mirror; a sample is fixed by the fixing adjusting frame; the laser is irradiated on the surface of the sample by the focusing lens; the photoelectric detector is used for receiving the laser passing through the optical filter and generating an electric signal; and the signal of the photoelectric detector is amplified by the filter amplifier. According to the two-tone femtosecond laser collinear pumping detecting thermal reflection system, femtosecond pulse lasers with different wavelengths are applied to pumping light and detecting light; the pumping light after being subjected to frequency doubling is filtered by the optical filter with high selective permeability; the interference of the pumping light to a detecting signal is avoided; and the accurate high-efficient measurement is realized.

Description

technical field [0001] The invention belongs to solid thermal conductivity testing technology, relates to ultrashort laser pulse pumping detection technology, in particular to a two-color femtosecond laser collinear pumping detection heat reflection system. Background technique [0002] Thin film materials have been widely used in microelectronics, optoelectronics and other fields, and these microdevices will generate extremely high heat flux density during operation, and heat accumulation will directly affect the working efficiency and reliability of such devices. It is extremely urgent to solve the heat dissipation problem of the above-mentioned micro-devices, which requires accurate characterization of the thermal transport properties of the thin-film materials that make up the above-mentioned micro-devices in order to reveal its heat transport mechanism. In the study of ultrafast thermodynamic processes, it is often necessary to use ultrashort pulse laser pump-probe tech...

AI Technical Summary

Problems solved by technology

However, the light elimination efficiency of existing nonlinear crystals is only 10 -3 to 10 -4 , very low signal-to-noise ratio

In the prior art, due to the low signal-to-noise ratio of the single-wavelength pumping detection system, the requirements for the optical path system of the pumping light and the detection light are extremely high, which makes the system structure complex and inconvenient to operate

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