Optically Pumped Far-Infrared Ammonia Lasers

Weiß, C. O.; Fourrier, M.; Gastaud, C.; Redon, M.

doi:10.1007/978-1-4613-2689-2_15

Cited by 10 publications

(20 citation statements)

References 42 publications

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“…Only the pairs of transitions exhibiting an exploitable molecular gain factor, i.e., within five orders of magnitude of the strongest one (here G m > 1 Â 10 À21 uG m ) are reported. Under these restrictions, a total of 326 potential laser lines accessible via 808 pump/laser combinations for 14 NH 3 (Table S3, Supporting Information) and 285 potential laser lines accessible via 733 pump/laser combinations for 15 NH 3 (Table S4, Supporting Information) are reported in this work. Subsets of these tables, displaying only the THz laser lines with the strongest potential, their paired MIR pump frequency and molecular gain factor, are reported in Table 1.…”

Section: Catalogs Of Mir-pumped Thz-laser Transitions Of Ammoniamentioning

confidence: 99%

“…An imperfect resonance reduces drastically the gain and then requires a very powerful pump laser to reach the lasing threshold. [14] THz spectrometers that use such molecular lasers pumped by CO 2 lasers are usually very bulky, energy intensive, and require both a lot of different molecules to cover the THz range and a strong expertise. [1,[15][16][17][18][19] Because of their continuous tunability, solid-state pump sources overcome the aforementioned difficulty to generate the adequate frequency for a molecular gain medium.…”

Section: Introductionmentioning

confidence: 99%

“…As THz molecular lasers pumped by a QCL will potentially generate a huge quantity of new THz frequencies, a method that would allow comparison and classification of laser lines by their lasing potential is more than ever needed. The aims of the present paper are threefold: 1) define a purely molecular-based figure of merit (i.e., excluding experimental and technical parameters proper to each laser design), hereafter called the molecular gain factor G m , that allows identification of the MIR/THz transitions pairs exhibiting the strongest lasing potential; 2) provide a list of possible THz laser lines that can be obtained using a MIR pump laser in the 10 μm range and ammonia as gain medium (both 14 NH 3 and 15 NH 3 ); 3) verify experimentally the validity of both our figure of merit and catalogs by detecting various laser lines up to 5.5 THz. In the following, after defining the molecular gain factor, we report two laser catalogs, for 14 NH 3 and 15 NH 3 , that have been built using available spectroscopic information on the HITRAN database.…”

Section: Introductionmentioning

confidence: 99%

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Optically Pumped Terahertz Molecular Laser: Gain Factor and Validation up to 5.5 THz

Mammez

Buchanan

Pirali

et al. 2022

Advanced Photonics Research

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Quantum cascade laser‐pumped terahertz (THz) gas lasers are at the edge of revolutionizing THz science where powerful yet tunable sources have long been lacking. Maybe one of the last remaining drawbacks to a wider use of these instruments lies in the lack of available databases of potentially lasing transitions for users. A new figure of merit, the molecular gain factor is proposed, that allows to discriminate transitions by their lasing potential. Using this factor, catalogs of THz laser lines of ammonia, both 14NH3 and 15NH3, up to 10 THz are reported. Demonstration of the use of these two catalogs, and of the pertinence of the molecular gain factor, is made by experimentally observing 32 laser lines of 14NH3 and 5 lines of 15NH3 up to 5.5 THz. Prospects to generalize the use of this molecular gain factor to a wide range of molecules are discussed.

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Section: Catalogs Of Mir-pumped Thz-laser Transitions Of Ammoniamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optically Pumped Terahertz Molecular Laser: Gain Factor and Validation up to 5.5 THz

Mammez

Buchanan

Pirali

et al. 2022

Advanced Photonics Research

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“…Moreover, the ammonia molecule has a high rotational constant and a fast relaxation rate, and was identified as an ideal molecule for THz lasing in the 1980s, without, however, the possibility to pump it with a CW CO2 laser. [12][13][14]. As shown in Fig.1(c) all these factors allow reaching an exceptionally high MIRàTHz conversion efficiency "#$ = 1% (i.e.…”

Section: Thz Molecular Lasermentioning

confidence: 99%

Quantum cascade laser-pumped terahertz molecular lasers: frequency noise and phase-locking using a 1560 nm frequency comb

Lampin¹,

Pagies²,

Santarelli³

et al. 2020

Opt. Express

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The recent demonstration of a terahertz (THz) molecular gas laser pumped by a mid-infrared quantum cascade laser (QCL) has opened up new perspectives for this family of sources, traditionally relying on CO2-laser pumping. A so far open question concerning QCL-pumped THz molecular lasers (MLs) is related to their spectral purity. Indeed, assessing their frequency/phase noise is crucial for a number of applications potentially exploiting these sources as local oscillators. Here this question is addressed by reporting the measurement of the frequency noise power spectral density (PSD) of a THz ML pumped by a 10.3µm-wavelength QCL, and emitting 1mW at 1.1THz in continuous wave. This is achieved by beating the ML frequency with the 1080 th harmonic of the repetition rate of a 1560nm frequency comb. We find a frequency noise PSD < 10Hz 2 /Hz (-95dBc/Hz) at 100kHz from the carrier. To demonstrate the effect of the stability of the pump laser on the spectral purity of the THz emission we also measure the frequency noise PSD of a CO2-laser-pumped 2.5THz ML, reaching 0.1Hz 2 /Hz (-105dBc/Hz) at 40kHz from the carrier, limited by the frequency noise of the frequency comb harmonic. Finally, we show that it is possible to actively phase-lock the QCL-pumped molecular laser to the frequency comb repetition rate harmonic by controlling the QCL current, demonstrating a sub-Hz linewidth.

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“…Other ways were also tried: pulsed CO 2 pumping, Stark tuning, isotopic CO 2 and/or isotopic NH 3 , Raman laser, and sequence band lasers pumping. 12 A number of lines were discovered but all these solutions were quite complicated, bulky, and expensive. Using QCL pumping, it is, in principle, possible to choose the transitions that allow high gain and generate interesting frequencies for applications.…”

Section: -2mentioning

confidence: 99%

Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

2016

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We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia) in gas state. The low-power (<60 mW) laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

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Optically Pumped Far-Infrared Ammonia Lasers

Cited by 10 publications

References 42 publications

Optically Pumped Terahertz Molecular Laser: Gain Factor and Validation up to 5.5 THz

Optically Pumped Terahertz Molecular Laser: Gain Factor and Validation up to 5.5 THz

Quantum cascade laser-pumped terahertz molecular lasers: frequency noise and phase-locking using a 1560 nm frequency comb

Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

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