Algaasgaas terahertz quantum cascade laser with goldbased. The reported technique is able to control and fully suppress higher order lateral modes in broadband terahertz quantum cascade lasers by introducing sideabsorbers to metalmetal waveguides. Highspeed modulation of a terahertz quantum cascade laser by. The terahertz thz frequency quantum cascade laser qcl is a compact source of thz radiation offering high power, high spectral purity and. Thz radiation was outcoupled through the midir waveguide facets. Grapheneintegrated metamaterial device for allelectrical. Bacon, timeresolved pumpprobe investigation of the terahertz quantum cascade laser, ph. Sirtori materiaux et phenomenes quantiques, universite paris 7 denis diderot.
Reflection imaging with terahertz quantumcascade laser. Pdf dispersion in a broadband terahertz quantum cascade laser. Diode laser thz qcl rf optical spectrum analyzer dc bias. Terahertz quantumcascade laser with active leakywave antenna amir a. The introduction of the cherenkov waveguide scheme in these devices grown on semiinsulating inp substrates enabled.
Injection locking of a terahertz quantum cascade laser to. We report on the engineering of broadband quantum cascade lasers qcls emitting at. Its operation is based on 3quantumwell 3qw modules, where the gaas qws are separated by al 0. Modeling and experiments yao chen et aloptimization of thz semi. Semiconductor terahertz lasers based on the quantum cascade design, so called terahertz quantum cascade lasers thz qcls, have become an established thz technology. A qcl is built by stacking up alternating layers of semiconductors with thicknesses of only a few atoms. Terahertz thz frequencies, which exploit a heterogeneous active region. The terahertz thz frequency quantum cascade laser qcl is a compact source of thz radiation offering high power, high spectral purity and moderate tunability. However, for many applications, a radiation source with a continuous coverage of a substantially larger frequency range is required. The sideabsorbers consist of a top metalization setback with respect to the laser ridge and an additional lossy metal. This chapter is dedicated to terahertz thz quantum cascade laser technology. The terahertz thz region of the electromagnetic spectrum is usually defined as ranging from 1 thz 300 micrometers in wavelength to 10 thz 30 micrometers in wavelength. Terahertz nanoscopy of plasmonic resonances with a quantum. Terahertz quantum cascade laser leiying ying, noriaki horiuchiikeda and hideki hirayamarecent citations transmission electron microscopy of algaasgaas quantum cascade laser structures t.
A terahertz quantum cascade laser qcl uses electron transitions between manmade quantum well levels to emit terahertz. We report on the dopplerfree saturation spectroscopy of a molecular transition at 3. Reno, and qing hu, towards thz dualcomb spectrometer based on quantum cascade laser frequency combs, itqw2015, the th international conference on intersubband transitions in quantum wells, vienna, austria, september 611 2015. Pdf dopplerfree spectroscopy with a terahertz quantum. Distinct regions of brain tissue rich in fat, proteins, and fluidfilled cavities are resolved showing the. Liu, terahertz quantum cascade lasers operating up to 200 k with optimized oscillator strength and improved injection tunneling, opt. We present a terahertz thz scattering nearfield optical microscope ssnom based on a quantum cascade laser implemented as both source and detector in a selfmixing scheme utilizing resonant quartz tuning forks as a sensitive nanopositioning element.
A quantum cascade laser qcl is a nextgeneration device that uses electron transitions between manmade quantum well levels, as opposed to traditional lasers that use transitions between atomic levels. Terahertz quantum cascade lasers quantum cascade lasers qcl are electricallypumped semiconductor lasers based on intersubband transition in the conduction band of the heterostructure. Beat notes are detected with a gaas diode mixer and a microwave spectrum analyzer, permitting very precise. In this dissertation we present the complete realization of semiconductorheterostructure lasers emitting in the thz and employing the quantum cascade technology. Hu department of electrical engineering and computer science, and. We found that a certain level of external optical feedback is tolerable as long as the free spectral range of. Terahertz sidebandtuned quantum cascade laser radiation andriy a. It was in october of 2001 that the first qc laser with a photon energy less than the semiconductor optical phonon energy was demonstrated at 4. Kainz, sebastian schonhuber, tobias zederbauer, donald macfarland, michael krall, christoph deutsch, martin brandstetter, pavel klang, werner schrenk, karl unterrainer, and gottfried strasser. We present the experimental study of the direct emission detection system based on the thz quantum cascade laser as a source and hot electron bolometer heb detector in view of its application as an optical communication system. Terahertz quantumcascadelaser source based on intracavity. Pdf thermoelectriccooled terahertz quantum cascade lasers. Pdf phaselocking a thz quantum cascade laser to a thz comb. Terahertz quantumcascade transmissionline metamaterials.
Frequency stabilization of a thz quantum cascade laser qcl. We have measured the spectral linewidths of three continuouswave quantum cascade lasers operating at terahertz frequencies by heterodyning the freerunning quantum cascade laser with two farinfrared gas lasers. The energy levels in a quantum cascade laser are formed by quantum mechanically bound states in an artificially grown semiconductor nanostructure. The operation of thz quantum cascade laser in the region of. Using this technique the first demonstration of beam scanning for a terahertz qclaser was reported from 35. We demonstrate biomedical imaging using a terahertz quantum cascade laser. Introduction last year marked the 20th anniversary of the invention and demonstration of the quantum cascade laser qcl at bell laboratories 1. The overall response is described by parallel contributions from the recti. Evaluation of material systems for thz quantum cascade laser. A lamb dip with a subdoppler linewidth of 170 khz is observed for a rotational transition of hdo. Algaasgaas terahertz quantum cascade laser with gold. The lasers active region is build by stacking the 228 modules. Slingerland p, baird c and giles r h 2012, application of multisubband selfconsistent energy balance method to terahertz quantum cascade lasers, semicond.
Reflected terahertz imaging of a logo on a universal serial bus usb flash disk is demonstrated. Pdf dispersion in a broadband terahertz quantum cascade. Terahertz thz quantum cascade lasers qcls are powerful radiation sources for highresolution and highsensitivity spectroscopy with a discrete spectrum between 2 and 5 thz as well as a continuous coverage of several ghz. A reflection imaging system based on the terahertz quantum well photodetector is presented. The homemade ssnom, based on a resonant tuning fork and metallic tip, operates in tapping mode with a spatial resolution of. Linfield, injection locking of a terahertz quantum cascade laser to a telecommunications wavelength frequency comb, optica 4, 10591064 2017. Nixon4 1 submillimeterwave technology laboratory, dept. Williams, hans callebaut, sushil kumar, and qing hua department of electrical engineering and computer science and research laboratory of electronics, massachusetts institute of technology, cambridge, massachusetts 029 john l. Recent progress in terahertz differencefrequency quantum. Thz source publications submillimeterwave technology.
Williams submitted to the department of electrical engineering and computer science on august 22, 2003, in partial ful. Pdf two terahertz quantum cascade lasers based on gaasal0. Osa injection locking of a terahertz quantum cascade laser. Pdf we present a terahertz quantum cascade laser operating on a thermoelectric cooler up to a recordhigh temperature of 210. Freeman, lalitha ponnampalam, haymen shams, reshma a. Phaselocking a thz quantum cascade laser to a thz comb through an alloptical beating. Goodhue 1photonics center, department of physics and applied phys ics, university of massachusetts lowell, lowell, massachusetts 01854, usa. Although the quantum cascade gain medium can be used to produce incoherent light in a superluminescent configuration, it is most commonly used in combination with an optical cavity to form a laser. In a quantum cascade laser, the mentioned quantum well structure is embedded in a waveguide, and the laser resonator is mostly of dbr or dfb type. Foremost among these developments has been the thz frequency quantum cascade laser qcl 3,4 a compact, electrically pumped source based on intersubband transitions in a quantum heterostructure. Gain dynamics in a heterogeneous terahertz quantum cascade laser. Osa terahertz quantumcascade lasers as highpower and. Terahertz quantum cascade laser qcl sources based on intracavity difference frequency generation are.
Evaluation of material systems for thz quantum cascade laser active regions hermann detz, aaron m. The quantum cascade laser as a terahertz local oscillator. Quantum cascade lasers qcl are semiconductor lasers that emit in the mid and longwave ir bands, and are. Thz quantum cascaded lasers qcl are high power solidstate electrically driven coherent light sources that span 15 thz 420 mev, 60300 m. Gain dynamics in a heterogeneous terahertz quantum cascade. The broadband response of the device was characterized by using thz timedomain spectroscopy, and the modulation characteristics such as the modulation depth and cutoff frequency were studied with a 2. Terahertz differencefrequency quantum cascade laser sources. Terahertz thz quantum cascade lasers sciencedirect.
Dopplerfree spectroscopy with a terahertz quantumcascade laser. Towards the bigger goal of realizing an active terahertz metamaterial to ultimately develop zeroindex terahertz quantumcascade lasers immune to spatial hole burning, or. Injection locking of a terahertz quantum cascade laser to a telecommunications wavelength frequency comb joshua r. Foremost among these developments has been the thzfrequency quantumcascade laser qcl 3,4 a compact, electrically pumped source based on intersubband transitions in a quantum heterostructure. Evaluation of material systems for thz quantum cascade.
Terahertz frequency quantum cascade lasers thz qcls are compact, semiconductor sources of coherent thz radiation, and have numerous potential applications in chemical sensing and industrial. Terahertz sidebandtuned quantum cascade laser radiation. The qcl is the most mature source of coherent farinfrared emission from 60 to 250 um, i. The terahertz thz quantum cascade laser1 qcl is a compact and coherent source of thz radiation, which is a unipolar device based on intersubband transitions in the conduction band of a speci. Population inversion and laser emission can be freely engineered. Boreiko center for astrophysics and space astronomy, ucb 593, university of colorado, boulder, colorado 80309 b. A high temperature threewell thz qcl emitting at 3.
What is the effect of doping locations on lasing frequency. Since its invention in 2001, the thz quantum cascade laser qcl has emerged as a compact semiconductor thz source capable of delivering milliwattlevel power or higher at various frequencies from 1. Terahertz quantum cascade lasers with copper metalmetal waveguides operating up to 178 k mikhail a. Thz quantum cascade lasers with wafer bonded active regions m. Terahertz quantumcascade laser with active leakywave. Pdf phaselocking a thz quantum cascade laser to a thz. The first qc laser was demonstrated at the much shorter wavelength of 4. Pdf thz communication system based on a thz quantum cascade. Foremost among these developments has been the thzfrequency quantumcascade laser qcl 3,4 a compact, electrically pumped source. Krysaan equivalent circuit model for terahertz quantum cascade lasers. Since then qc lasers have become the dominant midinfrared semiconductor laser sources, with spectral coverage from wavelengths of. Quantum cascade lasers qcls are novel semiconductor devices. Pdf thermoelectrically cooled thz quantum cascade laser.
This experiment demonstrates that the quantum well photodetector is potentially useful for reflection imaging applications. Terahertz quantum cascade lasers with copper metalmetal. Rp photonics encyclopedia quantum cascade lasers, qcl. Terahertz quantumcascade lasers qcls have now been demonstrated at frequencies of 1. Six years after their birth, terahertz quantumcascade lasers can now deliver milliwatts or more of continuouswave coherent radiation throughout the terahertz range the spectral regime. As such, these sources are particularly suited to the application of thz frequency imaging across a range of.
The purpose of this study was to determine the lasing frequency in thz when altering which of two wells were doped. Qclasers are the longest wavelength semiconductor laser. Linewidth and tuning characteristics of terahertz quantum. In this chapter, we report the fabrication of al 0. Highspeed modulation of a terahertz quantum cascade laser. Quantum cascade lasers rp photonics consulting on laser. Unlike ordinary band gap lasers known from everyday life laser pointers, bluraydvdcd drives, they are using a radically new concept. Longterm frequency and amplitude stability of a solidnitrogencooled, continuous wave thz quantum cascade laser pdf 162. Terahertz quantum cascade laser sources based on intracavity frequency mixing are currently the only monolithic electrically pumped semiconductor devices that can operate in the 16 thz spectral range at room temperature. There are also externalcavity lasers, where a wavelength tuning element such as a diffraction grating is part of the resonator. An optical modulation cutoff frequency of 105 15 mhz is reported. This is the simplest of the quantum cascade lasers.
The powercurrent relation and emission spectrum of this laser are shown in fig. Pdf thz communication system based on a thz quantum. A an introduction to quantum cascade lasers qcls april, 20 page 1 what is a qcl. We demonstrate the first lasing emission of a thermoelectrically cooled terahertz quantum cascade laser thz qcl. Osa imaging with a terahertz quantum cascade laser. We investigate the lightcurrentvoltage characteristics and emission spectra of 2. Terahertz differencefrequency quantum cascade laser. Linfield2 1harvard school of engineering and applied sciences, harvard university, cambridge, ma 028 2school of electronic and electrical engineering, university.
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