Fabrication And Application Of Organic Carbon Nanotubes Thin Film

Nonlinear optical material (NLOM) has many important applications in optical signal processing and functional optic modules and is a very active area in modern optics. Carbon nanotubes have excellent third-order nonlinear optical properties induced by the Carbon-Carbon a bond. It has quick recovery time, high damage threshold, low cost and stable chemical properties. It’s an very important research both in nonlinear optics and its application in optoelectronic devices field based on carbon nanotubes.This article will use polyimide (PI) as scattered material since it has the easiness in fabrication of film, good stability, high temperature resistance and transparent communication wavelength, we had a deep research both on nonlinear optical properties and its application in passively mode-locked fiber laser. Main work of this thesis is following:(1) This thesis analyzes the reason that SWCNT has third-order nonlinear characteristics in its physical and chemical structure and introduces its classification, properties and preparation methods, also elaborates the reason why choose SWCNT to make film.(2) SWCNT is cut and purified by chemical method. By a long time ultrasonic to let SWCNT disperse into PI uniformly, then we will use direct coating method to make SWCNT/PI film with different thickness, different concentrations0.5%,1%,2%.(3) Experiment measured the nonlinear refractive index and nonlinear absorption coefficient of SWCNT/PI film under1064nm wavelength by z scanning, get film with2.5%concentration, thickness of20um, its nonlinear absorption coefficient and nonlinear refractive index are:β=-6.1307×1010cm/W γ=-1.4199×10-13cm2/W, nonlinear third-order polarizability: χ(3)=2.702×10-11esu.(4) Experiment made SWCNT/PI film as optical saturable absorber, set up passive mode-locked laser, compare the result with the different thickness and different concentration of SWCNT/PI, and detect time/frequency domain signal by Spectrum Analyzer/light sampling oscilloscope, the output pulse repetition frequency of passive mode-locked laser in this article is16.8MHz, 3dB bandwidth of frequency spectrum is2.1nm, the average power of output pulse is0.998mW.