Single mode terahertz quantum cascade amplifier

Low-divergence single-mode terahertz quantum cascade laser

The operation of quantum cascade lasers has to date been demonstrated over a broad frequency range in the terahertz spectrum (from 4.4 THz to 1.2 THz)1–3. Most potential applications of terahertz quantum cascade lasers require a source that has an excellent spatial and spectral control of the radiated emission4–7. Here, we present a distributed feedback design of a double-metal waveguide quantu...

Lateral distributed-feedback gratings for single-mode, high-power terahertz quantum-cascade lasers.

We report on terahertz quantum-cascade lasers (THz QCLs) based on first-order lateral distributed-feedback (lDFB) gratings, which exhibit continuous-wave operation, high output powers (>8 mW), and single-mode emission at 3.3-3.4 THz. A general method is presented to determine the coupling coefficients of lateral gratings in terms of the coupled-mode theory, which demonstrates that large couplin...

Low divergence single-mode surface-emitting concentric-circular-grating terahertz quantum cascade lasers.

We report the design, fabrication and experimental characterization of surface-emitting terahertz (THz) frequency quantum cascade lasers (QCLs) with distributed feedback concentric-circular-gratings. Single-mode operation is achieved at 3.73 THz with a side-mode suppression ratio as high as ~30 dB. The device emits ~5 times the power of a ridge laser of similar dimensions, with little degradati...

Frequency stabilization of a single mode terahertz quantum cascade laser to the kilohertz level.

A simple analog locking circuit was shown to stabilize the beat signal between a 2.408 THz quantum cascade laser and a CH(2)DOH THz CO(2) optically pumped molecular laser to 3-4 kHz (FWHM). This is approximately a tenth of the observed long-term (t approximately sec) linewidth of the optically pumped laser showing that the feedback loop corrects for much of the mechanical and acoustic-induced f...

Nanowire terahertz quantum cascade lasers