Cryogen-Free High-Heat-Load Packaging of a surface emitting THz QCL

We present a high-heat-load (HHL) packaged terahertz quantum cascade laser (THz QCL) designed for cryogen-free operation. Using a four-stage Peltier cooler, we achieve stable laser operation at 185K, eliminating the need for liquid nitrogen or Stirling coolers. The QCL features a planar patch array antenna, reducing beam divergence, and is enclosed in an HHL package with a CuW insert and an AR-coated silicon window. Output power, emission spectra, and beam profiling confirm the device performance. This work demonstrates the feasibility of compact, cryogen-free THz QCL systems targeting real-world applications.