Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Electronic-coherence-mediated molecular nitrogen-ion lasing in a strong laser field

Jinming Chen, Jinping Yao, Haisu Zhang, Zhaoxiang Liu, Bo Xu, Wei Chu, Lingling Qiao, Zhenhua Wang, Julien Fatome, O. Faucher, Chengyin Wu, Ya Cheng

Published Sep 26, 2019• 38 citations
Publisher

Abstract

We report a combined theoretical and experimental investigation on the unambiguous role of electronic coherence underlying the generation of laserlike coherent emission from ${{\mathrm{N}}_{2}}^{+}$ ions launched in a strong laser field. The coherence manifests itself by giving rise to a dramatic enhancement of ${{\mathrm{N}}_{2}}^{+}$ laserlike radiation with two temporally separated pump laser pulses centered at 800- and 1580-nm wavelengths, respectively. We further show that coherent control of ${{\mathrm{N}}_{2}}^{+}$ lasing in a subfemtosecond timescale can be achieved by replacing the single 800-nm laser pulse with a pair of 800-nm laser pulses of adjustable time delay. The experimental results are well reproduced in theory using a three-level quantum model of ${{\mathrm{N}}_{2}}^{+}$ ions under the density matrix representation.

DOI
10.1103/physreva.100.031402

Related papers

Electronic quantum coherence induced by strong field molecular ionization

Jinming Chen, Jinping Yao, Haisu Zhang +9 more

The existence of electronic coherence can fundamentally change the scenario of nonlinear interaction of light with quantum systems such as atoms and molecules, which, however, has escaped from observation in the investigations of strong field nonlinear optics in the past several decades. Here, we report on the generation of electronic quantum coherence by strong field ionization of nitrogen molecules in an intense 800 nm laser field. The coherence is experimentally revealed by observing a resonant four-wave mixing process in which the two pump pulses centered at 800 nm and 1580 nm wavelengths are temporally separated from each other. The experimental observation is further reproduced by calculating the nonlinear polarization response of N_2^+ ions using a three-level quantum model. Our result suggests that strong field ionization provides a unique approach to generating a fully coherent molecular wavepacket encapsulating the rotational, vibrational, and electronic states.

arXiv:1808.03914•Aug 12, 2018•0 citations

Coherent control of the multiple wavelength lasing of ${\rm N}_2^ +$: coherence transfer and beyond

Xiang Zhang, Qi Lu, Zhedong Zhang +7 more

Nitrogen molecules pumped by intense femtosecond laser pulses give rise to coherent emission in the forward direction at a series of wavelengths, coined “air lasing.” We demonstrate the coherent control of these emissions via a pair of seeding pulses at two different frequencies at low pressures, revealing a coherence transfer through vibrational motion. It is found that the injection of a 427.8 nm (391.4 nm) seeding pulse results in its amplification at the expense of the 391.4 nm (427.8 nm) signal, demonstrating a competition between the two spectral components of the emission from the upper level population. Moreover, when the delay between the seeding and pump pulses is finely tuned, the coherent control of both transitions is observed via the coherence transfer. A microscopic molecular relaxation model reproduces these observations, highlighting the crucial role of electronic and vibrational coherences, as well as their coupling, during the lasing action.

Optica•Mar 29, 2021•32 citations

Comparative study of enhancement and suppression of N2+ lasing induced by coherent molecular rotational wave packets of N2 and N2+

Hongqiang Xie, Shu‐Ting Wu, Yihong Huang +7 more

${\mathrm{N}}_{2}^{+}$ lasing action involves the creation, evolution, and radiation of ions in intense laser fields. In this paper, we demonstrate that ${\mathrm{N}}_{2}^{+}$ lasing intensity can be enhanced by several times or totally suppressed by controlling the ionic creation and radiation processes through manipulation of the coherent molecular rotational wave packets of ${\mathrm{N}}_{2}$ and ${\mathrm{N}}_{2}^{+}$ with a pump-control scheme. Our results show that if a weak control pulse arrives at the revival moments of the ionic rotational wave packet, the lasing signal can be notably promoted, which is in contrast to observations in previous studies. Meanwhile, the modulation profiles of the lasing signals caused by molecular alignments of ${\mathrm{N}}_{2}$ and ${\mathrm{N}}_{2}^{+}$ are analyzed at length, revealing the double roles of the weak control pulse in inducing molecular alignment of ${\mathrm{N}}_{2}$ or monitoring the amplification of the ${\mathrm{N}}_{2}^{+}$ system by controlling electronic and rotational coherence. Moreover, by performing a Fourier transformation of the delay-dependent ${\mathrm{N}}_{2}^{+}$ lasing, the rotational wave-packet information of ${\mathrm{N}}_{2}$ and ${\mathrm{N}}_{2}^{+}$ is simultaneously retrieved.

Physical Review A•Apr 1, 2024•1 citation

Superradiance of molecular nitrogen ions in strong laser fields

Wang, Q., Pengji Ding, Shane G. Wilkins +5 more

We perform a combined theoretical and experimental investigation of the superradiance in the quantum coherent system generated by strong laser fields. The semiclassical theory of superradiance that includes the superradiant temporal profile, character duration, time delay, intensity is derived. The experimental data and theoretical predictions of 391-nm forward emission as a function of nitrogen gas pressure are compared and show good agreement. Our results not only demonstrate that the time-delayed optical amplification inside the molecular nitrogen ions is superradiance, but also reveal the quantum optical properties of strong-field physics.

arXiv:2105.00675•May 3, 2021•0 citations

Amplification characteristics of N2+ lasing at multiple wavelengths generated by polarization-modulated femtosecond laser fields

Shu‐Ting Wu, Qian Gao, Yihong Huang +4 more

Multiple gain routes complicate the amplification behaviors of N2+ lasing. A direct comparison of the amplification processes of various lasing lines of N2+ is still lacking to date, mainly because the efficient generation of different lasing lines requires different experimental conditions. In this work, to overcome the limitation, we use an intense polarization-modulated femtosecond laser pulse to simultaneously produce high-intensity N2+ lasing signals at 391 nm and 428 nm, permitting us readily performing their time-domain characterizations. Our results show that the primary amplification of 428-nm lasing is always retarded by a few picoseconds with respect to the probe pulse while the amplification of 391-nm lasing can be basically completed within the probe pulse duration at a relatively high gas pressure, and besides, the time duration of the former sustains several times longer than that of the latter. These observations indicate the non-negligible contribution of the initial electronic coherence established by the pump laser, apart from the external triggering pulse. For the 391-nm lasing, the seed amplification and superradiance can fiercely interplay within the probe pulse duration. However, for the 428-nm lasing, its amplification is in essence Raman-assisted superfluorescence due to the lacking of the initial electronic coherence and a direct triggering pulse. Our findings not only shed light on the physics of N2+ lasing but also promote the relevant studies on the collective emissions in the cascaded multi-level molecular ion system.

Optics Express•Aug 2, 2024•1 citation

arXiv : Superradiance of molecular nitrogen ions in strong laser fields

Qian Wang, Bitao Hu, Yun Zhang +4 more

We perform a combined theoretical and experimental investigation of the superradiance in the quantum coherent system generated by strong laser fields. The semiclassical theory of superradiance that includes the superradiant temporal profile, character duration, time delay, intensity is derived. The experimental data and theoretical predictions of 391-nm forward emission as a function of nitrogen gas pressure are compared and show good agreement. Our results not only demonstrate that the time-delayed optical amplification inside the molecular nitrogen ions is superradiance, but also reveal the quantum optical properties of strong-field physics.

•May 3, 2021•0 citations
We report a combined theoretical and experimental investigation on the unambiguous role of electronic coherence underlying the generation of laserlike coherent emission from N2+{{\mathrm{N}}_{2}}^{+}N2​+ ions launched in a strong laser field. The coherence manifests itself by giving rise to a dramatic enhancement of N2+{{\mathrm{N}}_{2}}^{+}N2​+ laserlike radiation with two temporally separated pump laser pulses centered at 800- and 1580-nm wavelengths, respectively. We further show that coherent control of N2+{{\mathrm{N}}_{2}}^{+}N2​+ lasing in a subfemtosecond timescale can be achieved by replacing the single 800-nm laser pulse with a pair of 800-nm laser pulses of adjustable time delay. The experimental results are well reproduced in theory using a three-level quantum model of N2+{{\mathrm{N}}_{2}}^{+}N2​+ ions under the density matrix representation.
The existence of electronic coherence can fundamentally change the scenario of nonlinear interaction of light with quantum systems such as atoms and molecules, which, however, has escaped from observation in the investigations of strong field nonlinear optics in the past several decades. Here, we report on the generation of electronic quantum coherence by strong field ionization of nitrogen molecules in an intense 800 nm laser field. The coherence is experimentally revealed by observing a resonant four-wave mixing process in which the two pump pulses centered at 800 nm and 1580 nm wavelengths are temporally separated from each other. The experimental observation is further reproduced by calculating the nonlinear polarization response of N_2^+ ions using a three-level quantum model. Our result suggests that strong field ionization provides a unique approach to generating a fully coherent molecular wavepacket encapsulating the rotational, vibrational, and electronic states.
Coherent control of the multiple wavelength lasing of N2+{\rm N}_2^ +N2+​: coherence transfer and beyond
Nitrogen molecules pumped by intense femtosecond laser pulses give rise to coherent emission in the forward direction at a series of wavelengths, coined “air lasing.” We demonstrate the coherent control of these emissions via a pair of seeding pulses at two different frequencies at low pressures, revealing a coherence transfer through vibrational motion. It is found that the injection of a 427.8 nm (391.4 nm) seeding pulse results in its amplification at the expense of the 391.4 nm (427.8 nm) signal, demonstrating a competition between the two spectral components of the emission from the upper level population. Moreover, when the delay between the seeding and pump pulses is finely tuned, the coherent control of both transitions is observed via the coherence transfer. A microscopic molecular relaxation model reproduces these observations, highlighting the crucial role of electronic and vibrational coherences, as well as their coupling, during the lasing action.
N2+{\mathrm{N}}_{2}^{+}N2+​ lasing action involves the creation, evolution, and radiation of ions in intense laser fields. In this paper, we demonstrate that N2+{\mathrm{N}}_{2}^{+}N2+​ lasing intensity can be enhanced by several times or totally suppressed by controlling the ionic creation and radiation processes through manipulation of the coherent molecular rotational wave packets of N2{\mathrm{N}}_{2}N2​ and N2+{\mathrm{N}}_{2}^{+}N2+​ with a pump-control scheme. Our results show that if a weak control pulse arrives at the revival moments of the ionic rotational wave packet, the lasing signal can be notably promoted, which is in contrast to observations in previous studies. Meanwhile, the modulation profiles of the lasing signals caused by molecular alignments of N2{\mathrm{N}}_{2}N2​ and N2+{\mathrm{N}}_{2}^{+}N2+​ are analyzed at length, revealing the double roles of the weak control pulse in inducing molecular alignment of N2{\mathrm{N}}_{2}N2​ or monitoring the amplification of the N2+{\mathrm{N}}_{2}^{+}N2+​ system by controlling electronic and rotational coherence. Moreover, by performing a Fourier transformation of the delay-dependent N2+{\mathrm{N}}_{2}^{+}N2+​ lasing, the rotational wave-packet information of N2{\mathrm{N}}_{2}N2​ and N2+{\mathrm{N}}_{2}^{+}N2+​ is simultaneously retrieved.
We perform a combined theoretical and experimental investigation of the superradiance in the quantum coherent system generated by strong laser fields. The semiclassical theory of superradiance that includes the superradiant temporal profile, character duration, time delay, intensity is derived. The experimental data and theoretical predictions of 391-nm forward emission as a function of nitrogen gas pressure are compared and show good agreement. Our results not only demonstrate that the time-delayed optical amplification inside the molecular nitrogen ions is superradiance, but also reveal the quantum optical properties of strong-field physics.
Multiple gain routes complicate the amplification behaviors of N2+ lasing. A direct comparison of the amplification processes of various lasing lines of N2+ is still lacking to date, mainly because the efficient generation of different lasing lines requires different experimental conditions. In this work, to overcome the limitation, we use an intense polarization-modulated femtosecond laser pulse to simultaneously produce high-intensity N2+ lasing signals at 391 nm and 428 nm, permitting us readily performing their time-domain characterizations. Our results show that the primary amplification of 428-nm lasing is always retarded by a few picoseconds with respect to the probe pulse while the amplification of 391-nm lasing can be basically completed within the probe pulse duration at a relatively high gas pressure, and besides, the time duration of the former sustains several times longer than that of the latter. These observations indicate the non-negligible contribution of the initial electronic coherence established by the pump laser, apart from the external triggering pulse. For the 391-nm lasing, the seed amplification and superradiance can fiercely interplay within the probe pulse duration. However, for the 428-nm lasing, its amplification is in essence Raman-assisted superfluorescence due to the lacking of the initial electronic coherence and a direct triggering pulse. Our findings not only shed light on the physics of N2+ lasing but also promote the relevant studies on the collective emissions in the cascaded multi-level molecular ion system.
We perform a combined theoretical and experimental investigation of the superradiance in the quantum coherent system generated by strong laser fields. The semiclassical theory of superradiance that includes the superradiant temporal profile, character duration, time delay, intensity is derived. The experimental data and theoretical predictions of 391-nm forward emission as a function of nitrogen gas pressure are compared and show good agreement. Our results not only demonstrate that the time-delayed optical amplification inside the molecular nitrogen ions is superradiance, but also reveal the quantum optical properties of strong-field physics.