Related Experiment Video
Updated: Jun 29, 2026
08:01
Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Causality and electromagnetic properties of active media
Bertil Nistad1, Johannes Skaar
1Department of Electronics and Telecommunications, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 15, 2008
Summary
This study explores active media and metamaterials, focusing on properties like permittivity and permeability. It discusses fundamental limitations related to causality, stability, and gain in these advanced materials.
Area of Science:
- Physics
- Materials Science
- Electromagnetism
Background:
- Active media and metamaterials offer unique electromagnetic properties.
- Understanding their behavior is crucial for advanced applications.
Purpose of the Study:
- To analyze key properties of active media and metamaterials.
- To investigate the implications of causality on their performance.
Main Methods:
- Theoretical analysis of permittivity and permeability.
- Examination of wave vector and refractive index behavior.
- Discussion of stability, refraction, and gain.
Main Results:
- Established several results concerning active media and metamaterials.
- Identified fundamental limitations imposed by causality.
- Detailed the interplay between material properties and wave propagation.
Conclusions:
- Causality imposes fundamental constraints on active media and metamaterials.
- Stability, gain, and refraction are intrinsically linked to material parameters.
- Further research into metamaterial design considering these limitations is warranted.
Related Concept Videos
01:10Dual Nature of Electromagnetic (EM) Radiation
Electromagnetic (EM) radiation consists of electric and magnetic field components oscillating in planes perpendicular to each other and mutually perpendicular to radiation propagation through space. EM radiation can be classified as a wave, characterized by the properties of waves such as wavelength (denoted as λ) and frequency (represented by ν).
Wavelength is the distance between two consecutive peaks (the highest point) or troughs (the lowest point) in the wave. Frequency is the number of...
Wavelength is the distance between two consecutive peaks (the highest point) or troughs (the lowest point) in the wave. Frequency is the number of...
01:30Electromagnetic Waves
James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his theory predicted “Electromagnetic waves”. He brought together all the work that had been done by brilliant physicists such as Oersted, Coulomb, Gauss, and Faraday and added his own insights to develop the overarching theory of electromagnetism. Maxwell’s equations, combined with the Lorentz force law, encompass all the laws of electricity and...
01:30Electromagnetic Waves in Matter
Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, or glass.
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
01:10Generating Electromagnetic Radiations
The German physicist Heinrich Hertz (1857–1894) was the first to generate and detect certain types of electromagnetic waves in the laboratory. Starting in 1887, he performed a series of experiments that confirmed the existence of electromagnetic waves and verified that they travel at the speed of light. Hertz used an alternating-current RLC (resistor-inductor-capacitor) circuit that resonated at a known frequency and connected it to a loop of wire. High voltages induced across the gap in the...
01:30Propagation Speed of Electromagnetic Waves
Electromagnetic waves are consistent with Ampere's law. Assuming there is no conduction current Ampere's law is given as:
01:12Interaction of EM Radiation with Matter: Spectroscopy
Electromagnetic (EM) radiation can be considered an oscillating electric and magnetic field propagating through a medium that can interact with matter in its path. The electric field in the radiation can interact with electrical charges in the atoms or molecules in the matter. On the other hand, the magnetic field can interact with the magnetic field in the atomic nucleus. The study of the interaction between electromagnetic radiation and matter is termed spectroscopy. Spectroscopy is the study...