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Population difference gratings created on vibrational transitions by nonoverlapping subcycle THz pulses
Rostislav Arkhipov1,2,3, Anton Pakhomov2, Mikhail Arkhipov1,2
1St. Petersburg State University, Saint Petersburg, Russian Federation.
Scientific Reports
|January 22, 2021
Summary
We demonstrate the creation and ultrafast control of population density gratings in multi-level resonant media using subcycle terahertz (THz) pulses. This novel method enables efficient manipulation of THz light interactions with matter.
Area of Science:
- Quantum Optics
- Nonlinear Optics
- Molecular Spectroscopy
Background:
- Population density gratings are crucial for controlling light-matter interactions.
- Terahertz (THz) pulses offer unique capabilities for probing molecular resonances.
- Ultrafast control of optical phenomena is a key area in modern physics.
Purpose of the Study:
- To theoretically investigate the creation and ultrafast control of population density gratings in multi-level resonant media.
- To explore the use of subcycle THz pulses for generating and manipulating these gratings.
- To analyze the role of quasi-unipolar pulses in enhancing grating modulation depth.
Main Methods:
- Approximate analytical solution of the time-dependent Schrödinger equation (TDSE) using perturbation theory.
- Numerical simulations employing Bloch equations for density matrix elements.
- Analysis of THz resonances in a [Formula: see text] molecule.
Main Results:
- Successful theoretical demonstration of population density grating creation and control using subcycle THz pulses.
- Identification of indirect pulse interaction via induced coherent polarization gratings.
- Quasi-unipolar subcycle pulses enhance excitation of higher quantum levels and grating modulation depth.
- Agreement between analytical and numerical results in the perturbative regime; non-harmonic grating shapes in the strong-field regime.
Conclusions:
- The study confirms the feasibility of creating and controlling population density gratings in multi-level resonant media with THz pulses.
- The findings suggest novel approaches for THz spectroscopy and ultrafast THz pulse control.
- The research opens new avenues for manipulating light-matter interactions in the THz frequency range.
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