Supercontinuum Generation In Solid Thin Plates And Its Applications In High Harmonic Generation

Generation of white continuum is an important research topic in the field of nonlinear optics.It has wide applications in ultrashort pulse generation,carrier-envelope phase(CEP)stabilization,high-harmonic generation(HHG),isolated attosecond pulse generation,ultrafast measurement and laser spectroscopy.To date,the most widely used method to generate high energy supercontinuum is injecting amplified pulses into hollow-core fiber to broaden the spectrum.Though hollow-core fiber system has the advantages of good beam quality and wide spectrum,it suffers beam-pointing and energy instability.What's more,the energy of output supercontinuum is always limited to mJ level,which is too low to generate high flux isolated attosecond pulse.In view of the above situation,this dissertation focused on the research of using solid thin plates instead of hollow-core fiber to generate high energy supercontinuum.Some innovation results have been obtained,which are summarized as follows:1: An octave-spanning supercontinuum was generated by using solid thin plates.The driving laser is FEMTOPOWER COMPACT PRO(CEP),which emits 0.8 mJ,30 fs,800 nm pulses at 1 kHz.To avoid the laser damage,0.2 mJ laser pulses were firstly injected into 7 fused silica plates with the thickness of 0.1 mm,0.18 mJ octave-spanning supercontinuum was achieved.Afterwards,by broadening the beam waist and increasing the distances between fused silica plates,0.35 mJ and 0.7 mJ supercontinuum was obtained respectively with 0.4 mJ and 0.8 mJ input pulses,corresponding to the efficiency of 87.5%.2: The mechanism of spectral broadening was analyzed experimentally.The main processes leading to supercontinuum generation were self-phase modulation(SPM)and self-steepening effect.Then the supercontinuum was compressed to 5.4 fs by chirped mirrors and a wedge pair.3: A continuum centered at 400 nm was generated when 0.2 mJ,33 fs,400 nm pulses are injected into 7 thin fused silica plates.After compressed by chirped mirrors,pulses of 0.12 mJ,8.6 fs were obtained.4: The CEP of compressed 5.4 fs pulse was stabilized by using solid-state supercontinuum in high precision.With a CEP stabilized oscillator,the amplifier CEP stabilization experiment was carried out.The octave-spanning supercontinuum was directly injected into the f-2f interferometer to measure CEP.Then the CEP was stabilized by feedback controlling one of the prisms in the compressor.In nearly 2 hours,the root mean square(RMS)of CEP error was 75.2 mrad with the integration time of 20 ms.5: The CEP stabilized 0.5 mJ,5.4 fs pulses were used to perform HHG experiment.By changing CEP,the continuous and discrete cutoff spectra were measured,which indicated that the CEP was successfully controlled.