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We study the feasibility of dispersion compensated terahertz quantum cascade lasers combs operating around 2.65–2.95 THz to perform multiheterodyne spectroscopy. The devices show short-term intermode beat note frequency drift after 30 μs, which indicates that reliable multiheterodyne spectroscopy over extended time-scale requires phase and timing correction to allow for coherent averaging.
In recent years, quantum cascade lasers (QCLs) have shown tremendous potential for the generation of frequency combs in the mid-infrared and terahertz portions of the electromagnetic spectrum. The research community has experienced success both in the theoretical understanding and experimental realization of QCL devices, capable of generating stable and broadband frequency combs. Specifically, it...
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...
We demonstrate a fast frequency tuning of a terahertz wire-laser. Using a piezo-actuator and a MEMS-plunger enables a tuning speed up to ∼15 KHz. Improved bonding-pad design of wire-lasers leads to larger fabrication yield and better mode discrimination.
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...
We report a novel tuning mechanism based on a “wire-laser” with subwavelength transverse dimensions(w≪λ). By manipulating the waveguided mode propagating outside the cavity, frequency tuning of ∼137GHz (3.6%) is demonstrated from a single-laser device at ∼3.8THz.
The authors demonstrate a novel tuning mechanism based on the unique feature of an unusual device termed "wire laser", which is defined as a laser whose dimension in the transverse direction w is much smaller than ??. As such, a large fraction of the mode propagates outside the solid core. Placing a movable object close to the wire laser allows direct manipulation of the evanescent laser...
Transitions between subbands in semiconductor quantum wells were suggested as a method to generate long wavelength radiation at customizable frequencies. The recently developed THz quantum-cascade lasers (QCL) hold great promise to bridge the so-called "THz gap" between conventional electronic and photonic devices.Using the high-power THz QCL and a 240x320 focal-plane array camera, we are...
We report operation of v ~ 2.7 THz quantum-cascade lasers (QCLs) up to 174 K. A new three-well active region, one-well injector scheme is utilized to lower the operating current densities. While the temperature performance of this design is comparable to that of the best published THz QCLs, lower operating current densities make this design a viable alternative.
Based on a robust THz gain medium that rapidly depopulates the lower state using resonant LO-phonons and a novel metal-metal waveguide structure for mode confinement, we have developed THz quantum cascade lasers with many performance records. These include but not limited to: pulsed operating temperature of ~170 K, the highest CW operating temperature of 117 K, long wavelength of ~207 mum, and the...
We report robust single-mode operation of surface-emitting distributed-feedback terahertz quantum-cascade lasers in metal-metal waveguides. Grating devices span a range of 0.35THz around 2.9THz, with 149K maximum pulsed operating temperature, and >6mW continuous-wave power at 5K.
A real-time reflection/transmission imaging system is demonstrated using a 50-mW, 4.3-THz quantum cascade laser source in a closed-cycle cryorefrigerator, with a 240times320 pixel microbolometer detector. A signal-to-noise ratio of 340 is achieved with a 20-frame/sec acquisition rate.
We report the demonstration of quantum-cascade lasers at ~4.4 THz (lambda ~ 68 mum) that emit 248 mW peak power in pulsed mode, and 138 mW continuous-wave power at heat-sink temperatures of 10 K.
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