High-power portable terahertz laser systems

Khalatpour, Ali; Paulsen, Andrew; Deimert, Chris; Wasilewski, Z. R.; Hu, Qing

doi:10.1038/s41566-020-00707-5

Cited by 276 publications

(206 citation statements)

References 39 publications

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“…Figure 1 shows the current status of the various semiconductor THz sources that directly generate THz waves from a dc power supply—note that sources that require other external microwave or light sources to generate THz waves (e.g., by multiplication or difference frequency) are not included in the figure. On the optical device side, p-germanium (p-Ge) lasers [ 4 ] and quantum cascade lasers (QCLs) have been studied [ 5 , 6 , 7 , 8 , 9 ]. Recently, room-temperature THz sources with difference frequency generation (DFG) using mid-infrared QCLs have been reported [ 10 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

Asada

Suzuki

2021

Sensors

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A compact source is important for various applications utilizing terahertz (THz) waves. In this paper, the recent progress in resonant-tunneling diode (RTD) THz oscillators, which are compact semiconductor THz sources, is reviewed, including principles and characteristics of oscillation, studies addressing high-frequency and high output power, a structure which can easily be fabricated, frequency tuning, spectral narrowing, different polarizations, and select applications. At present, fundamental oscillation up to 1.98 THz and output power of 0.7 mW at 1 THz by a large-scale array have been reported. For high-frequency and high output power, structures integrated with cylindrical and rectangular cavities have been proposed. Using oscillators integrated with varactor diodes and their arrays, wide electrical tuning of 400–900 GHz has been demonstrated. For spectral narrowing, a line width as narrow as 1 Hz has been obtained, through use of a phase-locked loop system with a frequency-tunable oscillator. Basic research for various applications—including imaging, spectroscopy, high-capacity wireless communication, and radar systems—of RTD oscillators has been carried out. Some recent results relating to these applications are discussed.

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Section: Introductionmentioning

confidence: 99%

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

Asada

Suzuki

2021

Sensors

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“…Unfortunately, this approach still shows two main limitations: Firstly, the limited mode-hop-free tunability range of the single device (few hundred MHz) is not suited for broadband spectroscopy; secondly, the need for cryogenic cooling has profoundly hampered QCLs' widespread use. In fact, despite the extreme miniaturization of the sources, the need of a liquid helium cryostat, of the corresponding liquid helium dewar, or (alternatively) the need of expensive low mechanical noise pulse tube refrigerators, make the experimental setup bulky, unfriendly to operate, and unfit for field deployment, even if first attempts have been recently pioneered [17,27,28].…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Terahertz Frequency Comb Generation in Difference-Frequency Quantum Cascade Lasers

et al. 2021

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Terahertz quantum cascade laser sources based on intra-cavity difference frequency generation from mid-IR devices are an important asset for applications in rotational molecular spectroscopy and sensing, being the only electrically pumped device able to operate in the 0.6–6 THz range without the need of bulky and expensive liquid helium cooling. Here we present comb operation obtained by intra-cavity mixing of a distributed feedback laser at λ = 6.5 μm and a Fabry–Pérot device at around λ = 6.9 μm. The resulting ultra-broadband THz emission extends from 1.8 to 3.3 THz, with a total output power of 8 μW at 78 K. The THz emission has been characterized by multi-heterodyne detection with a primary frequency standard referenced THz comb, obtained by optical rectification of near infrared pulses. The down-converted beatnotes, simultaneously acquired, confirm an equally spaced THz emission down to 1 MHz accuracy. In the future, this setup can be used for Fourier transform based evaluation of the phase relation among the emitted THz modes, paving the way to room-temperature, compact, and field-deployable metrological grade THz frequency combs.

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“…THz QCLs have achieved impressive performances in term of spectral coverage 17 , output power 18 and bandwidth 19,20 via carefully designed waveguides and active regions. Further, temperature operation has been extended to Peltier cooled operation 21,22 , with recent results showing operation up to 250 K 23 with further perspectives to achieve room temperature operation through new bandstructure designs and materials 24 . To extend the capabilities of these devices, nonlinear intracavity processes have been successfully exploited to generate frequencies in the telecom band~1.55 µm 25,26 , and shown the generation of frequency combs [27][28][29] with octave spanning bandwidth 20 .…”

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confidence: 99%

Millimeter wave photonics with terahertz semiconductor lasers

et al. 2021

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Millimeter wave (mmWave) generation using photonic techniques has so far been limited to the use of near-infrared lasers that are down-converted to the mmWave region. However, such methodologies do not currently benefit from a monolithic architecture and suffer from the quantum defect i.e. the difference in photon energies between the near-infrared and mmWave region, which can ultimately limit the conversion efficiency. Miniaturized terahertz (THz) quantum cascade lasers (QCLs) have inherent advantages in this respect: their low energy photons, ultrafast gain relaxation and high nonlinearities open up the possibility of innovatively integrating both laser action and mmWave generation in a single device. Here, we demonstrate intracavity mmWave generation within THz QCLs over the unprecedented range of 25 GHz to 500 GHz. Through ultrafast time resolved techniques, we highlight the importance of modal phases and that the process is a result of a giant second-order nonlinearity combined with a phase matched process between the THz and mmWave emission. Importantly, this work opens up the possibility of compact, low noise mmWave generation using modelocked THz frequency combs.

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High-power portable terahertz laser systems

Cited by 276 publications

References 39 publications

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

Direct Observation of Terahertz Frequency Comb Generation in Difference-Frequency Quantum Cascade Lasers

Millimeter wave photonics with terahertz semiconductor lasers

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