Related Experiment Video
Updated: Jun 20, 2026
09:36
Characterization of Anisotropic Leaky Mode Modulators for Holovideo
Published on: March 19, 2016
Mode coupling in thin-film chirped gratings
1Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo 185, Japan.
Optics Letters
|August 19, 2009
Summary
Mode coupling in thin-film chirped gratings is analyzed. Inclined light induces TE-TM coupling, impacting chirped-grating demultiplexer wavelength resolution.
Area of Science:
- Optics and Photonics
- Materials Science
Background:
- Thin-film gratings are crucial optical components.
- Understanding mode coupling is essential for device performance.
Purpose of the Study:
- To investigate mode coupling phenomena in thin-film chirped gratings.
- To analyze the influence of incident light angle on mode coupling.
- To relate mode coupling to the wavelength resolution of chirped-grating demultiplexers.
Main Methods:
- Theoretical analysis of mode coupling.
- Simulation of light propagation in chirped gratings.
- Mathematical description of TE-TM mode coupling.
Main Results:
- TE-TM mode coupling occurs for inclined incident light.
- The degree of mode coupling is dependent on the grating's chirp and incident angle.
- Mode coupling directly affects the wavelength resolution of the demultiplexer.
Conclusions:
- Mode coupling is a significant factor in thin-film chirped grating performance.
- Controlling mode coupling can optimize demultiplexer resolution.
- Further research into tailored grating designs can enhance optical device functionality.
Related Concept Videos
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
01:27Biasing of Metal-Semiconductor Junctions
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...