3.5 THz quantum-cascade laser emission from dual diagonal feedhorns

Abstract

Antenna-pattern measurements obtained from a double-metal supra-terahertz-frequency (supra-THz) quantum cascade laser (QCL) are presented. The QCL is mounted within a mechanically micro-machined waveguide cavity containing dual diagonal feedhorns. Operating in continuous-wave mode at 3.5 THz, and at an ambient temperature of ~60 K, QCL emission has been directed via the feedhorns to a supra-THz detector mounted on a multi-axis linear scanner. Comparison of simulated and measured far-field antenna patterns shows an excellent degree of correlation between beamwidth (full-width-half-maximum) and sidelobe content and a very substantial improvement when compared with unmounted devices. Additionally, a single output has been used to successfully illuminate and demonstrate an optical breadboard arrangement associated with a future supra-THz Earth observation space-borne payload. Our novel device has therefore provided a valuable demonstration of the effectiveness of supra-THz diagonal feedhorns and QCL devices for future space-borne ultra-high-frequency Earth-observing heterodyne radiometers.

The 2023 terahertz science and technology roadmap

“…Spaceborne THz deployments have been relatively few and instruments operating above 1 THz are even rarer [193]. This primarily arises from the relatively immature status of payload technology, though advancements are being made that increase the potential for THz observation in relation to both Earth observation and astronomy [197,198]. When compared with optical counterparts, THz structures are large and spatial imaging capabilities are inferior.…”

Development of Advanced Terahertz Optics Using Liquid Crystals

“…A linearly polarized, collimated beam from a 3.4-THz QCL [7] was passed through the LC device, which was orientated with the director parallel to the polarization direction and the transmitted power was measured using a helium-cooled bolometer. Modulation depths of 5% and 40% were achieved by adjusting the bias on the 13 µm and 100 µm devices respectively (Figure 3a and b).…”

Spectral analysis of a gas-phase reaction using self-mixing in a terahertz quantum cascade laser

“…The QCL used was a multimode QCL which was mounted within a precision micromachined copper block, with an integrated diagonal feedhorn [2]. In order to validate the SM method, the QCL emission spectrum was measured and compared to results obtained from Fourier-transform infrared (FTIR) spectroscopy with a Michelson interferometer (Fig.…”