| Summary: | 碩士 === 國立清華大學 === 光電工程研究所 === 104 === In this thesis, we demonstrate a high-sensitivity characterization of ultrashort mid-infrared pulse by a modified interferometric field autocorrelation (MIFA) method. MIR pulse measurement is a novel field in pulse measurement. We report on spectral phase retrieval of 43 MHz, ~100 fs, 3.3 μm pulses at energies down to 8.9 pJ by MIFA. Accordingly, a sensitivity of 3×10^-2 W^2 is achieved in the field of MIR pulse measurement. The simple setup consists of a Michelson interferometer, a 266-μm-thick AgGaSe2 crystal, and a homemade spectrometer with a thermoelectrically cooled InGaAs point detector, which is readily applicable to measuring a 20 fs (1.8 cycles) pulse at 3.3 μm. The feasibility is verified by comparing with the results obtained by simulation and frequency-resolved optical gating for the spectral phase modulation because of a 4-mm-thick Germanium plate. The reproducibility is tested by resolving the spectral phase modulation with several individual raw data. MIFA is a desirable pulse characterization technique because of (1) simplicity of configuration, (2) high sensitivity, and (3) algebraic data retrieval algorithm. The method has successfully characterized MIR pulses at 3.3 μm, exhibiting the potential in measuring pulses with longer wavelength.
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