We report the demonstration of a terahertz quantum-cascade laser that operates up to 164 K in pulsed mode and 117 continuous-wave at approximately 3.0 THz. The active region was based on resonant-phonon depopulation scheme metal-metal waveguide used for modal confinement. Copper copper thermocompression wafer bonding fabricate waveguide, which displayed improved thermal properties compared previous indium-gold method.

We report the development of a quantum cascade laser, at λ=87.2 μm, corresponding to 3.44 THz or 14.2 meV photon energy. The GaAs/Al0.15Ga0.85As laser structure utilizes longitudinal-optical (LO) phonon scattering for electron depopulation. Laser action is obtained in pulsed mode temperatures up 65 K, and 50% duty cycle 29 K. Operating 5 K mode, threshold current density 840 A/cm2, peak power approximately 2.5 mW. Based on relatively high operating cycles, we propose that direct...

Resonant-phonon terahertz quantum-cascade lasers operating up to a heat-sink temperature of 186 K are demonstrated. This record performance is achieved based on diagonal design, with the objective increase upper-state lifetime and therefore gain at elevated temperatures. The increased diagonality also lowers current densities by limiting flow parasitic leakage current. Quantitatively, characterized radiative oscillator strength that smaller factor two from least any previously published...

Quantum state engineering, the cornerstone of quantum photonic technologies, mainly relies on spontaneous parametric down-conversion and four-wave mixing, where one or two pump photons decay into a photon pair. Both these nonlinear effects require momentum conservation (i.e., phase-matching) for participating photons, which strongly limits versatility resulting states. Nonlinear metasurfaces, due to their subwavelength thickness, relax this constraint extend boundaries engineering. Here, we...

Room temperature operation of terahertz quantum cascade lasers (THz QCLs) has been a long-pursued goal to realize compact semiconductor THz sources. In this paper, we report on improving the maximum operating QCLs ∼ 261 K as step toward realization goal.

We report lasing at ∼3.0 THz (λ≈98–102 μm) in a quantum-cascade structure which mode confinement is provided by double-sided metal waveguide. The depopulation mechanism based on resonant phonon scattering, as our previous work. Lasing takes place pulsed up to heat-sink temperature of 77 K. waveguide consists metallic films placed above and below the 10-μm-thick multiple-quantum-well gain region, gives low losses modal factor nearly unity. Fabrication via low-temperature wafer bonding...

Demonstration of quantum-cascade lasers at ∼4.4 THz (λ∼68 µm), which are measured to emit 248 mW peak power in pulsed mode, and 138 continuous-wave heatsink temperatures 10 K, is reported. These based on a resonant-phonon depopulation scheme, use semi-insulating surface-plasmon waveguide.

The authors demonstrate the use of a terahertz quantum cascade laser (QCL) for real-time imaging in transmission mode at standoff distance 25meters. Lasing frequency was selected optimum within an atmospheric window ∼4.9THz. Coarse selection made by design QCL gain medium. Finer (to 0.1THz) judicious choice cavity length to adjust facet losses and therefore lasing threshold bias, order overlap peak Stark-shifted spectrum with window. Images are shown using uncooled 320×240 microbolometer camera.

We report the use of a ~50-mW peak power 4.3-THz quantum cascade laser (QCL) as an illumination source for real-time imaging with 320 times 240 element room-temperature microbolometer focal-plane array detector. The QCL is modulated synchronously differential imaging. Signal-to-noise ratios ~340 are achieved at 20-frame/s acquisition rate, and optical noise equivalent detector 4.3 THz estimated to be ~320 pW/radicHz. Both reflection transmission mode demonstrated

We measure microwave frequency (4-40 GHz) photoresistance at low magnetic field B, in high mobility 2D electron gas samples, excited by signals applied to a transmission line fabricated on the sample surface. Oscillatory vs B is observed. For excitation cyclotron resonance frequency, we find an unprecedented, giant relative (\Delta R)/R of up 250 percent. The apparently proportional square root power, and disappears as temperature increased.

We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2THz suitable space-based observatories. The uses a NbN superconducting hot-electron bolometer as mixer and quantum cascade laser operating at 2.8THz local oscillator. measure double sideband noise temperature 1400K 4.2K, find free-running QCL has sufficient power stability practical receiver, demonstrating unprecedented combination sensitivity stability.

We report cw operation of a quantum-cascade laser at 3.2 THz (λ≈94 μm) up to heat-sink temperature 93 K. Resonant longitudinal-optical phonon scattering is used depopulate the lower radiative state and low-loss metal–metal waveguide provide high modal confinement. Optical powers ∼1.8 mW 10 K ∼400 μW 78 are observed from single facet 40-μm-wide 1.35-mm-long device. A threshold current density 432 A/cm2 552 was obtained in mode. The same device lased 129 pulsed mode with 419 5

Single-mode surface-emitting distributed feedback terahertz quantum-cascade lasers operating around 2.9 THz are developed in metal-metal waveguides. A combination of techniques including precise control phase reflection at the facets, and use metal on sidewalls to eliminate higher-order lateral modes allow robust single-mode operation over a range approximately 0.35 THz. Single-lobed far-field radiation pattern is obtained using pi phase-shift center second-order Bragg grating. grating...

Recently, much attention has been focused on the generation of optical frequency combs from quantum cascade lasers. We discuss how fast detectors can be used to demonstrate mutual coherence such combs, and present an inequality that quantitatively evaluate their performance. several technical issues related shifted wave interference Fourier Transform spectroscopy (SWIFTS), show measurements elucidate time-domain properties showing they possess signatures both frequency-modulation...

Frequency combs based on terahertz quantum cascade lasers feature broadband coverage and high output powers in a compact package, making them an attractive option for spectroscopy.Here, we demonstrate the first multi-heterodyne spectroscopy using two laser combs.With just 100 µs of integration time, achieve peak signal-to-noise ratios exceeding 60 dB spectral greater than 250 GHz centered at 2.8 THz.Even with room-temperature detectors are able to 50 dB, as proof-of-principle use these...

We report Coulomb drag measurements between vertically-integrated quantum wires separated by a barrier only 15 nm wide. The temperature dependence of the resistance is measured in true one-dimensional (1D) regime where both have less than one 1D subband occupied. As function temperature, an upturn observed three distinct devices at $T^* \sim 1.6$ K. This crossover behaviour consistent with Tomonaga-Luttinger liquid models for 1D-1D wires.

Hyperspectral imaging is a spectroscopic technique that allows for the creation of images with pixels containing information from multiple spectral bands.At terahertz wavelengths, it has emerged as prominent tool number applications, ranging nonionizing cancer diagnosis and pharmaceutical characterization to nondestructive artifact testing.Contemporary systems typically rely on nonlinear optical downconversion fiber-based near-infrared femtosecond laser, requiring complex systems.Here, we...

We report operation of a terahertz quantum-cascade laser at 3.8 THz (λ≈79 μm) up to heat-sink temperature 137 K. A resonant phonon depopulation design was used with low-loss metal–metal waveguide, which provided confinement factor nearly unity. threshold current density 625 A/cm2 obtained in pulsed mode 5 Devices fabricated using conventional semi-insulating surface-plasmon waveguide lased 92 K 670

We compare the electronic temperatures and population inversion both below above lasing threshold in three quantum-cascade lasers (QCLs) operating at 2.8THz, 3.2THz, 3.8THz using microprobe band-to-band photoluminescence. In range, while ground-state temperature remains close to lattice one (90K–100K), upper radiative state heats up ∼200K. From measured thermal resistance power dependence of temperature, we get a value electron-lattice energy relaxation rate comparable with that typical...