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Broadband, high-intensity mid-infrared (mid-IR) ultrafast pulses are of great importance in a few applications such as frequency metrology, advanced spectroscopy, and medical surgery. Here we report the generation of broadband mid-IR pulses with µJ-level pulse energies using a single nonlinear medium of thin plate and a simple chirp compensation scheme. The system can be used for spectral broadening wavelength-tunable, mid-infrared pulses generated from an Optical Parameter Amplifier (OPA) system. Several pieces of solid thin plates made from different materials, including ZnSe, Ge and TiO2, were used in our experiments, to test their performances for the nonlinear spectral broadening. The experimental results demonstrated that the TiO2 thin plate has the highest spectral-broadening efficiency. While 2300 nm pulses with an initial bandwidth of approximately 200 nm (−30 dB level) and a pulse duration of 145 fs, was used as the seed light, octave-spanning nonlinear broadening could be achieved, leading to ⪆1300 nm (−30 dB level) output spectrum which corresponds to a Fourier Transform Limit (FTL) pulse duration of approximately 30 fs. After chirp compensation, the compensated pulse was measured to be approximately 67 fs, giving rise to a pulse compression ratio of approximately 2.2. The broadband spectra and ultrafast durations of the output pulses, generated from the system, highlight its great application potential in ultrafast spectroscopy, remote sensing, and gas detection.
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