研究目的
Investigating the generation of sub-terahertz and terahertz radiation in long-wavelength quantum cascade lasers, focusing on overcoming the challenges of high absorption in waveguides and achieving room-temperature operation.
研究成果
The research demonstrates the realization of sub-THz sources based on high-power, long-wavelength MIR DAU-QCLs, achieving sub-THz emission at ~700 GHz at room temperature. The low-frequency THz generation is mostly attributed to the optical rectification process, offering new opportunities for THz applications.
研究不足
The study is limited by the high free carrier absorption in the QCL waveguide and the THz frequency squared dependence of the DFG efficiency. Achieving high non-linearity for DFG and high mid-infrared pump powers simultaneously is challenging.
1：Experimental Design and Method Selection:
The study utilizes a high-performance, long-wavelength quantum cascade laser with a dual-upper-state active region for terahertz generation via difference frequency generation and optical rectification processes.
2：Sample Selection and Data Sources:
The laser structure consists of a 70-stage In
3：53Ga47As/In52Al48As quantum cascade structure grown on a semi-insulating InP substrate. List of Experimental Equipment and Materials:
The setup includes a Fourier transform infrared spectrometer, a helium-cooled bolometer, and a mercury cadmium telluride infrared detector for spectral measurements.
4：Experimental Procedures and Operational Workflow:
Measurements were acquired using 200-ns current pulses at a 10-kHz repetition rate, with optical filters used to distinguish output powers at different frequencies.
5：Data Analysis Methods:
The optical non-linearity χ(2) was calculated using the summation of contributions from double resonant and optical rectification processes.
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