Related Experiment Video
Updated: Jun 5, 2025
10:35
Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
8.7K
Resonant third-harmonic generation driven by out-of-equilibrium electron dynamics in sodium-based near-zero index
Matteo Silvestri1, Ambaresh Sahoo1, Luca Assogna1
1Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, 67100 L'Aquila, Italy.
Nanophotonics (Berlin, Germany)
|December 5, 2024
Summary
We demonstrate resonant third-harmonic generation in near-zero index thin films. Tuning the pump angle and film thickness optimizes this nonlinear optical process for novel ultraviolet light sources.
Area of Science:
- Nonlinear optics
- Condensed matter physics
- Materials science
Background:
- Intense optical excitation drives thin films out-of-equilibrium.
- Near-zero index (NZI) materials exhibit unique optical properties.
- Third-harmonic generation (THG) is a key nonlinear optical process.
Purpose of the Study:
- Investigate resonant THG in NZI thin films.
- Model collision-driven nonlinear dynamics in sodium.
- Explore THG modulation via pump angle and film thickness.
Main Methods:
- Landau weak coupling formalism for electron scattering.
- Derivation of novel hydrodynamic equations.
- Perturbative solution of hydrodynamic equations for THG modeling.
Main Results:
- THG resonance observed at the NZI resonance of the third harmonic signal.
- Reduced absorption in sodium allows THG tuning via pump radiation angle.
- Optimized THG conversion efficiency at a specific thin film thickness due to evanescent back-reflection.
Conclusions:
- Resonant THG in NZI thin films is feasible and tunable.
- Results pave the way for new ultraviolet light sources.
- Potential applications in integrated spectroscopy schemes.
Related Concept Videos
01:23Atomic Nuclei: Nuclear Relaxation Processes
622
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
622
01:12Double Resonance Techniques: Overview
191
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
191
01:05Atomic Nuclei: Magnetic Resonance
624
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
624