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

International Conference on Ultrafast Phenomena

Picosecond Pulse Multiphoton Coherent Propagation in Vapors

Jean‐Claude Diels, Herman A. Vanherzeele

Published Jan 1, 1984• 0 citations
Publisher

Abstract

We present a novel method for the study of multiphoton excitation by intense picosecond pulses in vapors. The technique, based on interferometric cross correlations of the multiphoton stimulated reradiation with the pulse itself, requires an interferometric delay line to generate accurately phased pulse sequences. Experimental data obtained with our method for two photon coherent propagation in lithium vapor, are in excellent agreement with a theoretical model.

DOI
10.1364/up.1984.tue15

Related papers

Two Photon Resonant Picosecond Pulse Propagation in Lithium Vapor

Anadi Mukherjee

The work of this dissertation has been to prove that the coherence of multiphoton excitation can be studied by an appropriately phased and time delayed sequence of pulses. An application of this fundamental study of coherence has been made for the enhancement of third harmonic generation. The coherent recovery of the energy lost to the two photon absorption process enalled a larger propagation distance for the fundamental than in an interaction which is incoherent or coherent, but not using a 90 degree phase shifted pulse pair. Phase matching over this longer propagation distance gave an enhancement of third harmonic generation.

•Aug 1, 1987•0 citations

Coherent Resonant Interaction and Harmonic Generation in Atomic Vapors.

Nandini Mukherjee

This work examines the use of higher order multiphoton resonances in higher harmonic generation together with judicious exploitation of coherent interaction properties to achieve efficient harmonic generation. A detailed experimental study on third harmonic generation in two photon resonant coherent interaction and a theoretical study on four photon resonant coherent interaction have been conducted. Two photon resonant coheren propagation in lithium vapor (2S-4S and 2S-3D interaction) has been studied in detail as a function of phase and delay of the interacting pulse sequence. Under coherent lossless propagation of 90 phase shifted pulse pair, third harmonic generation is enhanced. A maximum energy conversion efficiency of 1% was measured experimentally. This experiment shows that phase correlated pulse sequence can be used to control multiphoton coherent resonant effects. A larger two photon resonant enhancement does not result in more efficient harmonic generation, in agreement with the theoretical prediction. An accurate (to at least 0.5 A°) measurement of intensity dependent Stark shift has been done with the newly developed "interferometric wavemeter." Stark shifts as big as several pulse bandwidths (of picosecond pulses) result in a poor tuning of multiphoton resonance and become a limiting factor of resonant harmonic generation. A complete theory has been developed for harmonic generation in a four photon resonant coherent interaction. A numerical application of the theory to the Hg atom successfully interprets the experimental observations in terms of the phase dependent stimulated Raman scattering. With the intensity required for four photon resonant transition, the calculation predicts a dramatic Stark shift effect which completely destroys the resonance condition. This model provides a basis for the development of future schemes for efficient higher order coherent upconversion.

•Aug 1, 1987•0 citations

Picosecond Pulse Multiphoton Coherent Propagation in Vapors

Herman A. Vanherzeele, Jean‐Claude Diels

Springer series in chemical physics•Jan 1, 1984•0 citations

Free-precession decay of two-photon-induced coherence in Ca vapor

Masahiro Matsuoka, Hiroki Nakatsuka, Jumpei Okada

Calcium vapor has been excited by two-photon absorption of a mode-locked dye-laser pulse, and emission from a coherent superposition state of the $4{s}^{2}^{1}S_{0}$ and $4s3d^{1}D_{2}$ levels has been observed using a delayed off-resonant interrogation pulse in the picosecond regime. The emission signal intensity was measured as a function of the delay time of the interrogation pulse, and showed a peak well delayed from that of the dye-laser pulse. This reflects the fact that the induced coherence is expressed by a time integral of the excitation. The emission signal was then found to decay as a result of the Doppler effect. The above process is analyzed by Bloch and Maxwell equations. This is the first reported observation of the coherence of an atomic system induced by two-photon absorption, a coherence which persists after the passage of the excitation pulse and decays inhomogeneously as a result of thermal motion. In carrying out the experiment, deformation of the input dye-laser pulse during propagation through the two-photon resonant medium was carefully avoided.

Physical Review A•Sep 1, 1975•35 citations

Picosecond standoff multiphoton detection of gas phase species: initial results

Jerald B. Johnson, Kevin Lyon, William D. Murry +2 more

In the implementation of laser-induced fluorescence (LIF) for the detection of vapor-phase organic compounds that accompany hazardous materials, multiphoton excitation offers a significant advantage over single photon methods. In particular, if the absorption spectra of unwanted background molecules overlap that of the target molecule, single photon LIF is plagued by false positives. Multiphoton methods alleviate this difficulty by requiring that the target molecule be in resonance with multiple molecular transitions. A promising multiphoton method is stimulated Raman adiabatic passage (STIRAP). This method involves a counterintuitive sequence of laser pulses which is capable of transferring 100% of the target molecules to the desired excited state from which fluorescence is to be observed. As a precursor to more complex molecules, we demonstrate the STIRAP technique on sodium vapor using the 3p (2P1/2) ← 3s (2S1/2) and 5s (2S1/2) ← 3p (2P1/2) transitions. This is the first time STIRAP has been achieved on a vapor using picosecond lasers. We produced light to couple the states using two synchronously pumped OPG/OPAs (pumped by the 355 nm light from a picosecond YAG). We measured the fluorescence from the 5s state to both 3p states (2P1/2, 2P3/2) and from both 3p states to the 3s state with monochromator using a gated CCD to eliminate Rayleigh scattered light. Our results indicate a four to five-fold increase in the transfer efficiency to the 5s state when the laser pulse that couples the 3p and 5s states precedes the laser pulse tuned to the 3p ← 3s transition.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 6, 2008•2 citations

Coherent Multiphoton Resonant Interaction And Harmonic Generation

Arindum Mukherjee, Nandini Mukherjee, Grigory Arzumanyan +1 more

As a succession of two pulses propagates through a medium which exhibits a resonance (single or multiphoton), the resonant parts of the susceptibility will depend on the relative phase of the two pulses, provided the delay between the pulses is shorter than the phase relaxation time of the interaction. As a result of this "coherent interaction", the reradiation of the sample (the fluorescence, the absorption and the generation of harmonics) will be a periodic function of the phase difference and delay between the two pulses of the sequence 1. The study of these coherent effects is important, because one expect to find conditions under which the maximum harmonic conversion to much shorter wavelengths can be greatly enhanced 2. The presence of the multiphoton resonance enhances the nonlinear susceptibility responsible for the harmonic generation, but reduces also the maximum achievable conversion efficiency because of resonant losses (depletion of the fundamental by multiphoton absorption). The latter effect can be eliminated by a judicious choice of the pulse sequencing and phasing. In addition to demonstrating, for the first time, coherent interaction enhancement in harmonic generation, the data of third harmonic versus relative phase of the pulse sequences enable us to measure the phase angle of the third order susceptibility (hence the contribution of the continuum relative to that of the resonance).

International Conference on Ultrafast Phenomena•Jan 1, 1986•0 citations
We present a novel method for the study of multiphoton excitation by intense picosecond pulses in vapors. The technique, based on interferometric cross correlations of the multiphoton stimulated reradiation with the pulse itself, requires an interferometric delay line to generate accurately phased pulse sequences. Experimental data obtained with our method for two photon coherent propagation in lithium vapor, are in excellent agreement with a theoretical model.
The work of this dissertation has been to prove that the coherence of multiphoton excitation can be studied by an appropriately phased and time delayed sequence of pulses. An application of this fundamental study of coherence has been made for the enhancement of third harmonic generation. The coherent recovery of the energy lost to the two photon absorption process enalled a larger propagation distance for the fundamental than in an interaction which is incoherent or coherent, but not using a 90 degree phase shifted pulse pair. Phase matching over this longer propagation distance gave an enhancement of third harmonic generation.
This work examines the use of higher order multiphoton resonances in higher harmonic generation together with judicious exploitation of coherent interaction properties to achieve efficient harmonic generation. A detailed experimental study on third harmonic generation in two photon resonant coherent interaction and a theoretical study on four photon resonant coherent interaction have been conducted. Two photon resonant coheren propagation in lithium vapor (2S-4S and 2S-3D interaction) has been studied in detail as a function of phase and delay of the interacting pulse sequence. Under coherent lossless propagation of 90 phase shifted pulse pair, third harmonic generation is enhanced. A maximum energy conversion efficiency of 1% was measured experimentally. This experiment shows that phase correlated pulse sequence can be used to control multiphoton coherent resonant effects. A larger two photon resonant enhancement does not result in more efficient harmonic generation, in agreement with the theoretical prediction. An accurate (to at least 0.5 A°) measurement of intensity dependent Stark shift has been done with the newly developed "interferometric wavemeter." Stark shifts as big as several pulse bandwidths (of picosecond pulses) result in a poor tuning of multiphoton resonance and become a limiting factor of resonant harmonic generation. A complete theory has been developed for harmonic generation in a four photon resonant coherent interaction. A numerical application of the theory to the Hg atom successfully interprets the experimental observations in terms of the phase dependent stimulated Raman scattering. With the intensity required for four photon resonant transition, the calculation predicts a dramatic Stark shift effect which completely destroys the resonance condition. This model provides a basis for the development of future schemes for efficient higher order coherent upconversion.
Calcium vapor has been excited by two-photon absorption of a mode-locked dye-laser pulse, and emission from a coherent superposition state of the $4{s}^{2}^{1}S_{0}$ and 4s3d1D24s3d^{1}D_{2}4s3d1D2​ levels has been observed using a delayed off-resonant interrogation pulse in the picosecond regime. The emission signal intensity was measured as a function of the delay time of the interrogation pulse, and showed a peak well delayed from that of the dye-laser pulse. This reflects the fact that the induced coherence is expressed by a time integral of the excitation. The emission signal was then found to decay as a result of the Doppler effect. The above process is analyzed by Bloch and Maxwell equations. This is the first reported observation of the coherence of an atomic system induced by two-photon absorption, a coherence which persists after the passage of the excitation pulse and decays inhomogeneously as a result of thermal motion. In carrying out the experiment, deformation of the input dye-laser pulse during propagation through the two-photon resonant medium was carefully avoided.
In the implementation of laser-induced fluorescence (LIF) for the detection of vapor-phase organic compounds that accompany hazardous materials, multiphoton excitation offers a significant advantage over single photon methods. In particular, if the absorption spectra of unwanted background molecules overlap that of the target molecule, single photon LIF is plagued by false positives. Multiphoton methods alleviate this difficulty by requiring that the target molecule be in resonance with multiple molecular transitions. A promising multiphoton method is stimulated Raman adiabatic passage (STIRAP). This method involves a counterintuitive sequence of laser pulses which is capable of transferring 100% of the target molecules to the desired excited state from which fluorescence is to be observed. As a precursor to more complex molecules, we demonstrate the STIRAP technique on sodium vapor using the 3p (2P1/2) ← 3s (2S1/2) and 5s (2S1/2) ← 3p (2P1/2) transitions. This is the first time STIRAP has been achieved on a vapor using picosecond lasers. We produced light to couple the states using two synchronously pumped OPG/OPAs (pumped by the 355 nm light from a picosecond YAG). We measured the fluorescence from the 5s state to both 3p states (2P1/2, 2P3/2) and from both 3p states to the 3s state with monochromator using a gated CCD to eliminate Rayleigh scattered light. Our results indicate a four to five-fold increase in the transfer efficiency to the 5s state when the laser pulse that couples the 3p and 5s states precedes the laser pulse tuned to the 3p ← 3s transition.
As a succession of two pulses propagates through a medium which exhibits a resonance (single or multiphoton), the resonant parts of the susceptibility will depend on the relative phase of the two pulses, provided the delay between the pulses is shorter than the phase relaxation time of the interaction. As a result of this "coherent interaction", the reradiation of the sample (the fluorescence, the absorption and the generation of harmonics) will be a periodic function of the phase difference and delay between the two pulses of the sequence 1. The study of these coherent effects is important, because one expect to find conditions under which the maximum harmonic conversion to much shorter wavelengths can be greatly enhanced 2. The presence of the multiphoton resonance enhances the nonlinear susceptibility responsible for the harmonic generation, but reduces also the maximum achievable conversion efficiency because of resonant losses (depletion of the fundamental by multiphoton absorption). The latter effect can be eliminated by a judicious choice of the pulse sequencing and phasing. In addition to demonstrating, for the first time, coherent interaction enhancement in harmonic generation, the data of third harmonic versus relative phase of the pulse sequences enable us to measure the phase angle of the third order susceptibility (hence the contribution of the continuum relative to that of the resonance).