Research On The Noise Characteristic Of Femtosecond Laser Optical Frequency Comb

Research on the noise characteristic of femtosecond optical frequency comb is huge significant for precise optical measurement,time reference,attosecond pulse generation,coherent pulse synthesis,replication of optical frequency comb and its remote distribution.It is the foundation of laser output optimization and low noise femtosecond laser source,and also is the theoretical basis for laser noise reduction,noise compensation technique and broadband optical frequency comb generation.Unidirectional pulse propagation equation successfully describes the variation dynamics when pulse propagates in the media with detail information of complex electric field.Base on the modeling of Ti: sapphire femtosecond laser using unidirectional pulse propagation equation,in order to reduce the noise of femtosecond laser,we study the noise characteristic of optical frequency comb and achieve coherent synthesis.The main contents of this thesis include:1.Derivation of unidirectional pulse propagation equation and its numeric solution using split-step Fourier combined with 4th order Runge-Kutta method.2.Modeling of Ti: sapphire femtosecond laser based on unidirectional pulse propagation equation.We make numerical stimulation of the dynamics of the ultra-short pulses in the cavity and get pulses with 133 nm spectrum,47 fs pulse duration and 39 nJ pulse energy under the condition of-13 fs2 cavity net dispersion.We do experiments on the compact broadband tunable Ti: sapphire femtosecond laser and get tunable output ultrashort pulses ranging from 740 nm to 893 nm in spectral domain.The output power is 800 mW at 800 nm center wavelength.The output power is 420 mW at 890 nm center wavelength.The spectrum of wide-spectrum output ranges from 730 nm to 870 nm in spectral domain.3.Elaboration of basic theory of optical frequency comb noise.We add quantum limited noise into the numerical model of the femtosecond laser,get the stimulation results of elastic tape model and timing jitter characteristics.4.Experiments on the coherent synthesis of two independent Yb-doped fiber femtosecond lasers.We lock the repetition rate of the two lasers using balanced optical correlation,the residual timing jitter is 380 as.We lock the carrier envelope phase of the two lasers using an acoustic-optical modulator outside the cavity,the residual phase noise is 495 mrad.The coherent spectrum is stable after synthesis.