Physical Review A

Strong-field-induced N2+ lasing by phase control of free induction decay

Siqi Wang, Yao Fu, Erik Lötstedt, Jincheng Cao, Hongwei Zang, Helong Li, Kaoru Yamanouchi, Huailiang Xu

Published Sep 26, 2023• 10 citations

Abstract

We prepare ${{\mathrm{N}}_{2}}^{+}$ mostly in the vibrational ground ${X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}$ state by an ultraviolet 267-nm pulse and create the free induction decay (FID) of the $B{\phantom{\rule{0.16em}{0ex}}}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{u}}^{+}\ensuremath{-}{X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}$(0, 0) transition at 391 nm by a resonant excitation pulse. By controlling the phase shift of the FID using a near-IR control pulse through the dynamical Stark effect and rotational coherence, we reveal that the absorption spectrum of this transition, exhibiting a Lorentzian absorption profile, can be changed into a Fano-type profile, and then, a Lorentzian emission profile, resulting in ${{\mathrm{N}}_{2}}^{+}$ lasing. Our results shed light on the long-term controversy over the mechanism of strong-field-induced ${{\mathrm{N}}_{2}}^{+}$ lasing and reveal a general route to achieving amplification of light resonantly interacting with molecular ions without population inversion.

DOI: 10.1103/physreva.108.033113

Related papers

Mechanism and control of rotational coherence in femtosecond laser-driven N2+

Hongbin Lei, Guihua Li, Hongqiang Xie +5 more

Optics ExpressJul 10, 20206 citations

Quantum erasing of laser emission in N2+

Rostyslav Danylo, G. Lambert, Yi Liu +3 more

arXiv:2004.07785Optics LettersJul 20, 202014 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

Physical Review AApr 1, 20241 citation

Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N2+

Xiang Zhang, Qi Lu, Yalei Zhu +14 more

arXiv:2205.07405Ultrafast ScienceDec 4, 202316 citations

Lasing without population inversion in N2+

A. Mysyrowicz, Rostyslav Danylo, Aurélien Houard +7 more

APL PhotonicsNov 1, 201975 citations

Ultraviolet supercontinuum generation driven by ionic coherence in a strong laser field

Hongbin Lei, Jinping Yao, Jing Zhao +11 more

Nature CommunicationsJul 14, 202255 citations

Physical Review A

Strong-field-induced N2+ lasing by phase control of free induction decay

Siqi Wang, Yao Fu, Erik Lötstedt, Jincheng Cao, Hongwei Zang, Helong Li, Kaoru Yamanouchi, Huailiang Xu

Published Sep 26, 2023• 10 citations

Publisher

Abstract

We prepare

{{\mathrm{N}}_{2}}^{+}

mostly in the vibrational ground

{X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}

state by an ultraviolet 267-nm pulse and create the free induction decay (FID) of the

B{\phantom{\rule{0.16em}{0ex}}}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{u}}^{+}\ensuremath{-}{X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}

(0, 0) transition at 391 nm by a resonant excitation pulse. By controlling the phase shift of the FID using a near-IR control pulse through the dynamical Stark effect and rotational coherence, we reveal that the absorption spectrum of this transition, exhibiting a Lorentzian absorption profile, can be changed into a Fano-type profile, and then, a Lorentzian emission profile, resulting in

{{\mathrm{N}}_{2}}^{+}

lasing. Our results shed light on the long-term controversy over the mechanism of strong-field-induced

{{\mathrm{N}}_{2}}^{+}

lasing and reveal a general route to achieving amplification of light resonantly interacting with molecular ions without population inversion.

DOI: 10.1103/physreva.108.033113

Related papers

Mechanism and control of rotational coherence in femtosecond laser-driven N2+

Hongbin Lei, Guihua Li, Hongqiang Xie +5 more

We investigate the formation of rotational coherence of N2+ resonantly interacting with an intense femtosecond laser field by numerical simulations based on a strong-field ionization-coupling model described with the density matrix formalism. The created N2+ system is unique in many aspects: the variable total population within the pump duration due to the intensity-dependent ionization injection, the readily accessible resonance owing to the effect of Stark shift, and the involvement of a few dozen of quantum states. By regarding the N2+ system as an open and non-stationary Λ-type cascaded multi-level system, we quantitatively studied the dependence of rotational coherence in different electronic-vibrational states of N2+ on the alignment angle θ and the pumping intensity. Our simulation results indicate that the quantum coherence between the neighbouring rotational states of J, J+2 in the vibrational state ν=0, 1 of the ground state of N2+ can be changed from a negative to a positive. The significant contribution of rotational coherence to inducing an extra gain or absorption of N2+ air lasing is further verified by solving the Maxwell's propagating equation. The finding provides crucial clues on how to manipulate N2+ lasing by controlling the rotational coherence and paves the way to studying strong-field quantum optics effects such as lasing without inversion and electromagnetically induced transparency in molecular ionic systems.We investigate the formation of rotational coherence of N2+ resonantly interacting with an intense femtosecond laser field by numerical simulations based on a strong-field ionization-coupling model described with the density matrix formalism. The created N2+ system is unique in many aspects: the variable total population within the pump duration due to the intensity-dependent ionization injection, the readily accessible resonance owing to the effect of Stark shift, and the involvement of a few dozen of quantum states. By regarding the N2+ system as an open and non-stationary Λ-type cascaded multi-level system, we quantitatively studied the dependence of rotational coherence in different electronic-vibrational states of N2+ on the alignment angle θ and the pumping intensity. Our simulation results indicate that the quantum coherence between the neighbouring rotational states of J, J+2 in the vibrational state ν=0, 1 of the ground state of N2+ can be changed from a negative to a positive. The significant contribution of rotational coherence to inducing an extra gain or absorption of N2+ air lasing is further verified by solving the Maxwell's propagating equation. The finding provides crucial clues on how to manipulate N2+ lasing by controlling the rotational coherence and paves the way to studying strong-field quantum optics effects such as lasing without inversion and electromagnetically induced transparency in molecular ionic systems.

Optics ExpressJul 10, 20206 citations

Quantum erasing of laser emission in N2+

Rostyslav Danylo, G. Lambert, Yi Liu +3 more

Cavity-free lasing of N 2 + induced by a femtosecond laser pulse at 800 nm is nearly totally suppressed by a delayed twin control pulse. We explain this surprising effect within the V-scheme of lasing without population inversion. A fast transfer of population between nitrogen ionic states X 2 Σ g + and A 2 Π u , induced by the second pulse, terminates the conditions for amplification in the system. The appearance of short lasing bursts at delays corresponding to revivals of rotational wave packets is explained along the same lines.Cavity-free lasing of N 2 + induced by a femtosecond laser pulse at 800 nm is nearly totally suppressed by a delayed twin control pulse. We explain this surprising effect within the V-scheme of lasing without population inversion. A fast transfer of population between nitrogen ionic states X 2 Σ g + and A 2 Π u , induced by the second pulse, terminates the conditions for amplification in the system. The appearance of short lasing bursts at delays corresponding to revivals of rotational wave packets is explained along the same lines.

arXiv:2004.07785Optics LettersJul 20, 202014 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.${\mathrm{N}}_{2}^{+}$ 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 AApr 1, 20241 citation

Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N2+

Xiang Zhang, Qi Lu, Yalei Zhu +14 more

Quantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter, regardless of how many optical frequencies are involved. Here, we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser pulses. In the spectral domain, Fano resonance is observed in the emission spectrum, where a laser-assisted dynamic Stark effect creates the continuum. In the time domain, the fast-evolving emission is measured, revealing the nature of free-induction decay arising from quantum radiation and molecular cooperativity. These findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be universal. The present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance.Quantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter, regardless of how many optical frequencies are involved. Here, we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser pulses. In the spectral domain, Fano resonance is observed in the emission spectrum, where a laser-assisted dynamic Stark effect creates the continuum. In the time domain, the fast-evolving emission is measured, revealing the nature of free-induction decay arising from quantum radiation and molecular cooperativity. These findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be universal. The present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance.

arXiv:2205.07405Ultrafast ScienceDec 4, 202316 citations

Lasing without population inversion in N2+

A. Mysyrowicz, Rostyslav Danylo, Aurélien Houard +7 more

We experimentally demonstrate the existence of long-lived coherent polarizations coupling simultaneously ground state X (X2Σg+) to excited states A (A2Πu) and B (B2Σu+) of N2+ inside a plasma created by a short intense laser pulse at 800 nm. This three-level V-scheme arrangement is responsible for a strong optical gain without population inversion at the B–X transition at 391.4 nm. Simulations based on Maxwell-Bloch equations reproduce well the kinetics and the pressure dependence of the gain.We experimentally demonstrate the existence of long-lived coherent polarizations coupling simultaneously ground state X (X2Σg+) to excited states A (A2Πu) and B (B2Σu+) of N2+ inside a plasma created by a short intense laser pulse at 800 nm. This three-level V-scheme arrangement is responsible for a strong optical gain without population inversion at the B–X transition at 391.4 nm. Simulations based on Maxwell-Bloch equations reproduce well the kinetics and the pressure dependence of the gain.

APL PhotonicsNov 1, 201975 citations

Ultraviolet supercontinuum generation driven by ionic coherence in a strong laser field

Hongbin Lei, Jinping Yao, Jing Zhao +11 more

Supercontinuum (SC) light sources hold versatile applications in many fields ranging from imaging microscopic structural dynamics to achieving frequency comb metrology. Although such broadband light sources are readily accessible in the visible and near infrared regime, the ultraviolet (UV) extension of SC spectrum is still challenging. Here, we demonstrate that the joint contribution of strong field ionization and quantum resonance leads to the unexpected UV continuum radiation spanning the 100 nm bandwidth in molecular nitrogen ions. Quantum coherences in a bunch of ionic levels are found to be created by dynamic Stark-assisted multiphoton resonances following tunneling ionization. We show that the dynamical evolution of the coherence-enhanced polarization wave gives rise to laser-assisted continuum emission inside the laser field and free-induction decay after the laser field, which jointly contribute to the SC generation together with fifth harmonics. As proof of principle, we also show the application of the SC radiation in the absorption spectroscopy. This work offers an alternative scheme for constructing exotic SC sources, and opens up the territory of ionic quantum optics in the strong-field regime.Supercontinuum (SC) light sources hold versatile applications in many fields ranging from imaging microscopic structural dynamics to achieving frequency comb metrology. Although such broadband light sources are readily accessible in the visible and near infrared regime, the ultraviolet (UV) extension of SC spectrum is still challenging. Here, we demonstrate that the joint contribution of strong field ionization and quantum resonance leads to the unexpected UV continuum radiation spanning the 100 nm bandwidth in molecular nitrogen ions. Quantum coherences in a bunch of ionic levels are found to be created by dynamic Stark-assisted multiphoton resonances following tunneling ionization. We show that the dynamical evolution of the coherence-enhanced polarization wave gives rise to laser-assisted continuum emission inside the laser field and free-induction decay after the laser field, which jointly contribute to the SC generation together with fifth harmonics. As proof of principle, we also show the application of the SC radiation in the absorption spectroscopy. This work offers an alternative scheme for constructing exotic SC sources, and opens up the territory of ionic quantum optics in the strong-field regime.

Nature CommunicationsJul 14, 202255 citations

We prepare

{{\mathrm{N}}_{2}}^{+}

mostly in the vibrational ground

{X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}

state by an ultraviolet 267-nm pulse and create the free induction decay (FID) of the

B{\phantom{\rule{0.16em}{0ex}}}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{u}}^{+}\ensuremath{-}{X}^{2}{{\mathrm{\ensuremath{\Sigma}}}_{g}}^{+}

{{\mathrm{N}}_{2}}^{+}

lasing. Our results shed light on the long-term controversy over the mechanism of strong-field-induced

{{\mathrm{N}}_{2}}^{+}

lasing and reveal a general route to achieving amplification of light resonantly interacting with molecular ions without population inversion.

{\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.