Development of backward-wave oscillators for terahertz applications

Ives, R. Lawrence; Kory, C.L.; Read, Michael; Neilson, Jeff; Caplan, M.; Chubun, N.N.; Schwartzkopf, S.; Witherspoon, R.

doi:10.1117/12.506905

Cited by 29 publications

(9 citation statements)

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“…THz /8π 2 νt sp is the cross section for the lasing transition, the spontaneous emission lifetime is t sp = 3h 0 λ 3 THz /16π 3 μ 2 23 , where μ 2 23 = | 2|μ|3 | 2 is the dipole matrix element for the laser transition, and ν is the half width of the gain profile, approximated as ν ≈ ν 2 D + ν 2 p , where ν D and ν p are the Dopplerbroadening (for the terahertz transition) and pressurebroadening line widths, respectively.…”

Section: Three-level Model Equationsmentioning

confidence: 99%

“…The need for powerful tunable narrow-band sources to span the "terahertz gap" between 0.3 and 3.0 THz continues to grow as next-generation wireless-communication systems demand increasing bandwidth and new opportunities arise for intrinsically short-range communications facilitated by strong frequency-dependent atmosphericwater-vapor absorption [1]. Most terahertz sources fall into one of two categories: lower-frequency electronic sources for which power decreases with increasing frequency, such as microwave oscillators or frequency multipliers [2], backward-wave oscillators [3], and gyrotrons [4] and higher-frequency optical sources for which power increases with increasing frequency, such as terahertz quantum cascade lasers [5] and difference-frequency lasers [6][7][8]. The region in between, where powerful sources are lacking, is known as the terahertz gap.…”

Section: Introductionmentioning

confidence: 99%

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Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

2021

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Quantum-cascade-laser-(QCL) pumped molecular lasers (QPMLs) have recently been introduced as a source of powerful (>1 mW) tunable (>1 THz) narrow-band (<10 kHz) continuous-wave terahertz radiation. The performance of these lasers depends critically on molecular collision physics, pump saturation, and on the design of the laser cavity. Using a validated three-level model that captures the essential collision and saturation behaviors of the QPML gas nitrous oxide (N 2 O), we explore how the threshold pump power and output terahertz power depend on the pump power and gas pressure, as well as on the diameter, length, and output-coupler transmissivity of a cylindrical cavity. The analysis indicates that maximum power occurs as pump saturation is minimized in a manner that depends much more sensitively on pressure than on cell diameter, length, or transmissivity. A near-optimal compact laser cavity can produce tens of milliwatts of power tunable over frequencies above 1 THz when pumped by a multiwatt QCL.

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Section: Three-level Model Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

2021

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“…The saturation-dependent infrared absorption coefficient for a given transition is obtained by nonlinearly solving equations (3)(4)(5)(6). Pump saturation is described in (6) by the population difference (N tot 1 − N tot 2 ) between levels 1 and 2.…”

Section: Three-level Model Equationsmentioning

confidence: 99%

“…The need for powerful, tunable, narrow-band sources to span the "terahertz gap" between 0.3-3.0 THz continues to grow as next generation wireless-communication systems demand increasing bandwidth and new opportunities arise for intrinsically short-range communications facilitated by strong, frequency-dependent atmospheric water vapor absorption [1]. Most terahertz sources fall into one of two categories: lower-frequency electronic sources such as microwave oscillators or frequency multipliers [2], backward-wave oscillators [3], and gyrotrons [4] whose power decreases with increasing frequency; and higher-frequency optical sources such as terahertz quantum cascade lasers [5] and difference-frequency lasers [6][7][8] whose power increases with increasing frequency. The region in between, where powerful sources are lacking, is known as the terahertz gap.…”

Section: Introductionmentioning

confidence: 99%

Maximizing performance of quantum cascade laser-pumped molecular lasers

Wang,

Johnson,

Everitt

2021

Preprint

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Quantum cascade laser-pumped molecular lasers (QPMLs) have recently been introduced as a new source of powerful (> 1 mW), tunable (> 1 THz), narrow-band (< 10 kHz), continuous-wave terahertz radiation. The performance of these lasers depends critically on molecular collision physics, pump saturation, and on the design of the laser cavity. Using a validated three-level model that captures the essential collision and saturation behaviors of the QPML gas nitrous oxide (N2O), we explore how threshold pump power and output terahertz power depend on pump power, gas pressure, as well as on the diameter, length, and output-coupler transmissivity of a cylindrical cavity. The analysis indicates that maximum power occurs as pump saturation is minimized in a manner that depends much more sensitively on pressure than on cell diameter, length, or transmissivity. A compact laser cavity with 10-100 times smaller volume than the nominally optimal geometry is able to achieve at least 95% of the maximum laser performance.

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“…Although many advances have been made in development of solid-state semiconductor lasers and oscillators [3], the potential of traditional vacuum sources such as klystrons, magnetrons, and backward wave oscillators remains virtually untapped. Recent advances in modern micromachining technologies suggest that this was a natural route to fabricate small structures, such as cavities, waveguides, and slow wave structures (SWS), which might be used in the scaleddown vacuum electron tubes operating at far greater frequencies [4,5]. Based on this mechanism, a novel 0.14 THz-overmoded surface wave oscillator (SWO), which could deliver an output power around 40 MW, was designed and reported in APMC2008 proceedings [6].…”

Section: Introductionmentioning

confidence: 99%

Modeling and simulation of a powerful terahertz generator based on Cherenkov superradiance

Zhang

Wang

Tian

2010

Micro & Optical Tech Letters

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In this article, the preliminary studies of coherent stimulated terahertz radiation from intense, subnanosecond electron beam are presented. The mechanism of terahertz pulse generation is associated with self-bunching of the beam and slippage of the wave over the whole electron flow. This so-called Cherenkov superradiance (SR) was used to propose a compact terahertz generator with high peak power. A large cross section (overmoded), slow wave structure was designed to support the high power handling capability, and the mode competition was avoided by operating the device in the surface wave status. With 2.5D particle-in-cell simulation, we investigated the ''hot'' characteristics of the proposed superradiant terahertz generator and found that the SR peak power could be further increased by optimizing the amplitude profile of electron pulse.ABSTRACT: Interference scenarios between ZigBee transceivers in a multiple integrated laser engagement system have been presented. The permissible output power of interfering transmitters measured in the case of a direct link and a direct link with repeaters. The later was reduced by 10 dB relative to that for the direct link.

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Development of backward-wave oscillators for terahertz applications

Cited by 29 publications

References 0 publications

Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

Maximizing performance of quantum cascade laser-pumped molecular lasers

Modeling and simulation of a powerful terahertz generator based on Cherenkov superradiance

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