Nonlinear rovibrational polarization response of water vapor to ultrashort long-wave infrared pulses

Abstract

We study the rovibrational polarization response of water vapor using a fully correlated optical Bloch equation approach employing data from the HITRAN database. For a 10-μm long-wave infrared pulse the resulting linear response is negative, with a negative nonlinear response at intermediate intensities and a positive value at higher intensities. For a model atmosphere comprised of the electronic response of argon combined with the rovibrational response of water vapor this leads to a weakened positive nonlinear response at intermediate intensities. Propagation simulations using a simplified noncorrelated approach show the resultant reduction in the peak filament intensity sustained during filamentation due to the presence of the water vapor.

Exact Numerical Methods for Stationary-State-Based Quantum Dynamics of Complex Polyatomic Molecules

“…Due to the rapidly increasing amount of high-quality data placed into molecular spectroscopy databases, it is worth mentioning here that laser-induced dynamics can also be simulated for molecules for which spectroscopic databases, containing rovibrational energy levels as well as transition amplitudes between the corresponding eigenstates, are available. This interesting approach was pursued, for example, in Owens et al (2017) and Schuh et al (2017). reported the extension of the time-independent nuclear-motion code GE-NIUSH with time-dependent quantum-dynamical features and results are presented there for the coherent inhibition and enhancement of tunneling in NH 3 isotopomers.…”

THz generation from laser-induced breakdown in pressurized molecular gases: on the way to terahertz remote sensing of the atmospheres of Mars and Venus

“…In that case, one has to solve thousands of ordinary differential equations for each point in space instead of just a few in our case, so the time required for simulations would grow up accordingly from total of several months to many years. The (t, r+z) propagation simulations with inclusion of nonlinear rovibrational response are possible only if one truncates this system to the system consisting fewer ordinary differential equations [32]. However, the validity of this truncation [32] is limited to the intensity of ∼10TW cm −2 .…”

“…The (t, r+z) propagation simulations with inclusion of nonlinear rovibrational response are possible only if one truncates this system to the system consisting fewer ordinary differential equations [32]. However, the validity of this truncation [32] is limited to the intensity of ∼10TW cm −2 . In our experiment and simulations the intensity up to ∼1000TW cm −2 is attained, therefore the truncation suggested in [32] cannot be applied straightforwardly in our experimental conditions.…”

“…However, the validity of this truncation [32] is limited to the intensity of ∼10TW cm −2 . In our experiment and simulations the intensity up to ∼1000TW cm −2 is attained, therefore the truncation suggested in [32] cannot be applied straightforwardly in our experimental conditions. Indeed, the calculation of vacuum intensity in the geometry of our experiment yields I v ≈2 PW cm −2 .…”

Simulation of LWIR TW ultrashort pulses over kilometer ranges in the atmosphere

“…Beyond the linear contribution from rovibrational response, nonlinear contributions are to be expected for high enough intensities. In order to include these into simulations, we applied the optical Bloch equations to transition data from the HITRAN database 21 . Since the amount of data in HITRAN is rather prohibitive, a selection procedure based on transition strength and detuning from the carrier frequency was applied, reducing the number of transitions from more than 140,000 to 12,709.…”