We present key developments towards atmospheric chemistry studies using terahertz quantum-cascade lasers (QCLs), including ~1-cm 3-scale integration of THz QCLs with waveguides and antennas using precision micromachining, and broadband multimode spectroscopy based on detector-free self-mixing.
Waveguide integration of terahertz quantum cascade lasers (THz QCLs) is demonstrated at frequencies above 4.7 THz. A precision micromachining technique, followed by diamond-turning and electrolessplating has been used to manufacture hollow rectangular waveguides with integrated diagonal feedhorns. It is shown that surface roughness at the ≈ 1 μm level is achieved, enabling outcoupling of radiation in the 4.75-5.05 THz band, with a divergence angle of < 5 • along the plane of the QCLs substrate.
We have demonstrated waveguide integration of terahertz quantum cascade
lasers (THz QCLs) at frequencies above 4.7 THz. A precision
micromachining technique, followed by diamond-turning and
electroless-plating has been used to manufacture hollow rectangular
waveguides with integrated diagonal feedhorns. We show that surface
roughness at the 1μm level is achieved, enabling outcoupling of
radiation in the 4.75–5.05 THz band, with a divergence angle of 5°
along the plane of the QCL substrate.
Fig. 1. Shows the thickness of the LCD layer (left pane) and fused quartz window (right pane) extracted from a total variance analysis of the THz-time domain signal [6]
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