Rotational Quantum Beat Lasing Without Inversion

Abstract

In standard lasers, light amplification requires population inversion between an upper and a lower state to break the reciprocity between absorption and stimulated emission. However, in a medium prepared in a specific superposition state, quantum interference may fully suppress absorption while leaving stimulated emission intact, opening the possibility of lasing without inversion. Here we show that lasing without inversion arises naturally during propagation of intense femtosecond laser pulses in air. It is triggered by the combination of molecular ionization and molecular alignment, both unavoidable in intense light fields. The effect could enable inversionless amplification of broadband radiation in many molecular gases, opening unusual opportunities for remote sensing.

References in corpus (12)

• Ultrashort filaments of light in weakly-ionized, optically-transparent media
• High-brightness switchable multi-wavelength remote laser in air
• Population Redistribution among Multiple Electronic States of Molecular Nitrogen Ions in Strong Laser Fields
• Recollision induced superradiance of ionized nitrogen molecules
• One-Electron Ionization of Multielectron Systems in Strong Nonresonant Laser Fields
• Self-seeded lasing in ionized air pumped by 800 nm femtosecond laser pulses
• Remote creation of strong and coherent emissions in air with two-color ultrafast laser pulses
• Signature of superradiance from a nitrogen gas plasma channel produced by strong field ionization
• Self-induced white-light seeding laser in a femtosecond laser filament
• Transient gain from $N_2^{+}$ in light filaments
• Coherent control of superradiance from nitrogen ions pumped with femtosecond pulses
• Exit momentum and instantaneous ionization rate of nonadiabatic tunneling ionization in elliptically polarized laser fields

Cited by in corpus (13)

• Electronic State Population Dynamics upon Ultrafast Strong Field Ionization and Fragmentation of Molecular Nitrogen
• Strong Field Ionization of Water II: Electronic and Nuclear Dynamics En Route to Double Ionization
• Structured air lasing of N2+
• Photon retention in coherently excited nitrogen ions
• N${}_2^{+}$ Lasing: Gain and Absorption in the Presence of Rotational Coherence
• Control of ${\text{N}}_2^{+}$ Air Lasing
• Amplification of light pulses with orbital angular momentum (OAM) in nitrogen ions lasing
• Electronic-vibrational dynamics and coherence in x-ray transient absorption of N2+ induced by strong-field ionization
• Controlling the polarization of nitrogen ion lasing
• A quantum model of lasing without inversion
• Ramsey interferometry through coherent $X^2{\Sigma }_g^{+}-A^2{\Pi }_u-B^2{\Sigma }_u^{+}$ coupling and population transfer in N${}_2^{+}$ air laser
• Revisiting self-seeding mechanism by generating vector ultraviolet N${}_2^{+}$ lasing
• Exponential enhancement of sensitivity in Ramsey interferometry with optically thick ensemble of atoms