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We report an extensive study of the effect of an additional dielectric layer on the frequency of terahertz quantum cascade lasers (QCLs). QCLs with third-order distributed feedback structure at frequencies of 3.5 and 4.7 THz are used in our experiment. The applied dielectric layer is either Silicon dioxide (SiO2) or Polymethylmethacrylaat (PMMA). We find that both dielectric layers can shift the lasing...
We demonstrate broadband terahertz laser frequency combs, compact semiconductor devices that combine the high power of lasers with the broad spectra of pulsed sources.
By introducing coupled microstrip antennas on distributed feedback terahertz quantum-cascade lasers, the radiation efficiency of each aperture is greatly enhanced. Single mode emission from a 31-period antenna-coupled perfectly phase matched (PM) third-order DFB laser yields ∼ 4 times improvement in output power comparing with a traditional corrugated third-order DFB laser fabricated on the same gain...
A terahertz pulse emitter is fabricated alongside a quantum cascade laser with a metal-metal waveguide. Terahertz pulses are used to measure the gain of the laser ridge, which is clamped above threshold to 18 cm−1.
We report a novel laser cavity design in third-order distributed feedback terahertz quantum-cascade lasers based on true phase-matching technique. This approach dramatically increases the usable length of third-order DFB lasers and leads to even narrower beam patterns and likely higher output power. Single frequency emissions from 150 apertures (5.6-mm long device) are coherently added up to form...
The maximum operating temperature of previously reported terahertz quantum-cascade lasers (QCLs) has empirically been limited to a value of ~ ħω/kB. Here, we report a new design scheme for terahertz QCLs and achieve 163-K operation for a 1.8-THz QCL, which is a factor of 1.9 larger than ħω/kB.
We report single-mode operation of phase-locked arrays of surface-emitting distributed-feedback terahertz quantum-cascade lasers. Carefully-designed phase-sector locks lasers in-phase, creating tighter beam-patterns along the phased-array direction (FWHM ≈ 10°). This method allows beam-steering applications at terahertz frequencies.
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