Optical Fiber Light Source For Coherent Anti Stokes Raman Scattering Imaging Based On Four Wave Mixing

Coherent anti-Stokes Raman scattering?CARS?microimaging technology is an unmarked optical nonlinear imaging technology.It has the ability of non-invasive and three-dimensional tomography,and has a good application prospect in the field of life science.The traditional space optical CARS technology is based on solid pulse laser.The system has large structure,poor stability,high price and needs special maintenance,which restricts its popularization and application.In order to overcome these problems,this paper studies the all fiber CARS fiber parametric generator based on the fiber four wave mixing effect,studies the basic principle of fiber four wave mixing,and uses this principle to guide the experimental design of the CARS optical fiber parametric generator and obtains the experimental results.This research has a great effect on the development of the new CARS imaging technology.The important application value mainly includes the following contents:1.The four wave mixing effect in optical fiber is theoretically analyzed.From the nonlinear theory of optical fiber,the generation mechanism of four wave mixing is described in detail.On this basis,the factor of nonlinear coefficient,fiber length,pump power,departure effect and other factors affecting the conversion efficiency of four wave mixing are analyzed,and the realization of CARS light is made clear.Parameters of short pulse fiber pump source and nonlinear optical fiber needed for fiber parameters.2.In the study of the pump source used in the CARS imaging fiber parametric generator,the average power of two pump sources with repeated frequency of6.4MHz and 23MHz as the pump source of the CARS imaging fiber parametric generator was selected in the single wavelength pump source experiment.The average power of the pump was amplified to 1.5W and 2W;in the tunable pump source system,the seed source of picosecond pulse was put through the first stage After broadening the pulse width and introducing a certain linear chirp,the spectrum broadened to 5nm,and the tunable filter was connected to the wavelength tuning of the pump light,and the high peak power laser pulse output was then amplified by the cladding layer.3.In the tunable pump wavelength experiment,a new four wave mixing relationship is established between the signal light and the idle frequency light with the change of the pump wavelength.When pumping high nonlinear optical fiber,the tunable range of the pump source is 1026¹034nm,the signal tuning range is982nm⁹93nm,the idle frequency tuning range is 1123nm¹139nm,when the pump wavelength is 1032nm,the highest conversion efficiency of signal light and idle frequency light is 7%and 20%respectively,and the central wavelength of signal light and idle frequency light is 988m and 1132nm respectively.4.When the pumping photonic crystal fiber,the tunable range of the pump source is 1025¹036nm,the signal light is adjustable in the 842⁹42nm range,the idle frequency is adjustable within the 1150¹308nm range.When the pump wavelength is 1033m,the maximum conversion efficiency of the signal light and idle frequency light is reached,respectively,20%and 10.2%,the central wavelengths of the signal light and the idle frequency light is 906nm and 1192nm respectively.The shortest wavelength of the signal light can be tuned to 842nm,the longest wavelength of the idle frequency light reaches 1308nm,which lays the foundation for the study of the optical fiber parameter generator used in coherent anti Stokes Raman scattering imaging,and the frequency difference between the pump light and the signal light covers 963cm^-12120cm^-1.