Construction Of In-Situ High-Pressure Z-Scan System

Nonlinear optics has a wide range of application prospects in laser technology,optical communication,information storage and many other aspects,and has potential application value and scientific significance.The Z-scan technique is a method of obtaining nonlinear optical coefficients by measurement.The nonlinear refractive index and nonlinear absorption coefficient of materials can be measured to provide basic data for material performance improvement.The device and method thereof are relatively simple and have high sensitivity.Under high pressure,due to the reduction of atomic spacing,the crystal structure will change accordingly,so the physical and chemical properties of the material will change accordingly.The higher-order nonlinear optical response is closely related to the crystal configuration.Therefore,exploring the nonlinear optical properties of materials under high-pressure can broaden the thinking of materials.Based on this,we built an in-situ high-pressure nonlinear optical test system to study the nonlinear refractive index and absorption coefficient of materials under high pressure.This paper describes the system from the aspects of system construction,theoretical model,optical path design and optical path construction.These include:Design and construction of high-pressure Z-scan system: The high-pressure Z-scanning optical path system includes various parts as follows.Beam part is composed of picosecond laser,radio frequency driver(RF),acousto-optic modulator(AOM)and adjusted beam lifting device;optical path beam expansion and collimation part is composed of plano-convex lens and mirror;microscope objective part is composed of a microscope objective lens and a plano-convex lens;the high-pressure sample translation part is composed of a translation stage,a three-dimensional combined adjustment frame and a rotary stage;the first signal receiving part is composed of a half mirror,a plano-convex lens and No.1 detector;the second signal receiving part is composed of plano-convex lens,aperture and No.2 detector;the imaging part is composed of white light source,plano-convex lens,microscope objective lens,half mirror,mirror,CCD and display screen.Software of high voltage Z-scan optical path system: The software program,software acquisition process and optical test method of Z scan optical system are introduced.Software acquisition process: through the laser program software to set laser power,frequency and other parameters;Lab View software is used to control the movement of the translation platform and obtain the collected data.Test method for high-voltage Z-scan optical path: Turn on the laser,adjust the parameters,turn on the acoustro-optic modulator power supply,the detection signal is low-frequency signal,the power meter measures the reference power of the laser,turn on the white light source,ensure that the laser fully reaches the sample through CCD imaging,adjust the mirror to ensure that the detector receives the signal,and start the program for data acquisition.The nonlinear refraction of carbon disulfide(CS2)under different pressures has been measured and analyzed.