研究目的
Investigating THz generation in organic crystals (DAST) by optical rectification (OR) of intense Mid–Infrared (MIR) pulses to achieve high THz energy densities and understand crystal damage thresholds.
研究成果
The study demonstrates that THz generation in organic crystals driven by sub 100 fs, 3.9 μm pulses can achieve remarkably broadband THz spectra exceeding 10 THz and high THz energy densities of 3.1 mJ/cm2 without crystal damage at pump fluences > 150 mJ/cm2. This is attributed to the small pump photon energy being below the crystal absorption edge, suppressing heating by multiphoton absorption. The efficiency could potentially be improved by optimizing the crystal thickness.
研究不足
The study is limited by the need to optimize the beam profile due to the non-Gaussian shape of the OPCPA output beam and the necessity to prevent crystal damage through thermal heating by reducing the repetition rate. Future improvements could focus on matching the crystal thickness to the effective generation length to further improve efficiency.
1：Experimental Design and Method Selection:
The study utilizes Optical Parametric Chirped-Pulse Amplification (OPCPA) technology for generating THz in organic crystals through optical rectification.
2：Sample Selection and Data Sources:
DAST organic crystals are used, pumped by
3：9 μm OPCPA pulses. List of Experimental Equipment and Materials:
Includes a high-energy OPCPA system, DAST crystals, irises for beam profile optimization, a chopper to reduce repetition rate, long pass filters for THz separation, a pyroelectric detector for THz energy measurement, and a Michelson interferometer for spectrum recording.
4：Experimental Procedures and Operational Workflow:
The pump pulse is delivered to the crystal in an almost collimated geometry, with beam size adjusted to match the crystal size. Beam profile is optimized with two irises. A chopper reduces the repetition rate to prevent crystal damage. THz radiation is separated from the mid-IR pump pulse using long pass filters, and its energy and spectrum are measured.
5：Data Analysis Methods:
The THz spectrum is analyzed using autocorrelation measurements, and conversion efficiency is calculated with respect to pump fluence.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
