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Related Concept Videos

Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)01:22

Spin–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...
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–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...
Characteristics of Series Resonant Circuit01:24

Characteristics of Series Resonant Circuit

Series resonance occurs in a circuit containing inductive (L), capacitive (C), and resistive (R) elements connected sequentially. At the resonance frequency, the inductive and capacitive reactances are equal in magnitude but opposite in sign, effectively canceling each other. This causes the circuit's impedance is minimal, primarily determined by the resistance R. The resonant frequency of an RLC circuit is defined as:
Double Resonance Techniques: Overview01:12

Double Resonance Techniques: Overview

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...
¹H NMR: Long-Range Coupling01:27

¹H NMR: Long-Range Coupling

The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
Spin–Spin Coupling Constant: Overview01:08

Spin–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...

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Fabrication and Characterization of Superconducting Resonators
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[A new tunable SOI micro-ring resonator with three coupling points].

Zhi-Quan Li1, Xin Zhang, Yu-Chao Sun

  • 1College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China. lzq54@ysu.edu.cn

Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu
|August 3, 2013
PubMed
Summary
This summary is machine-generated.

A novel tunable silicon micro-ring resonator with three coupling points offers adjustable optical spectrum output. This design achieves a high quality factor and large free spectral range (FSR) by altering feedback waveguide properties.

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Area of Science:

  • Photonics and Optical Engineering
  • Materials Science (Silicon-on-Insulator)

Context:

  • Micro-ring resonators are crucial components in integrated photonics for wavelength filtering and signal processing.
  • Tunability of optical devices is essential for dynamic control in optical communication and sensing systems.

Purpose:

  • To propose and simulate a new tunable single micro-ring resonator structure with three coupling points.
  • To investigate the tunability of the output optical spectrum by modifying the feedback waveguide's length or temperature.
  • To analyze the performance metrics including free spectral range (FSR) and quality factor.

Summary:

  • A novel silicon-on-insulator (SOI) micro-ring resonator with three coupling points was designed based on coupled mode theory and transmission matrix.
  • Simulations using Matlab demonstrate that the output optical spectrum is tunable by altering the feedback waveguide's length or temperature.
  • Achieved a free spectral range (FSR) of 43.8 nm and a quality factor of 1.25 x 10^5 with a coupling coefficient k=0.018, exhibiting narrow bandwidth and high Q-factor.

Impact:

  • This resonator offers a high-quality factor, narrow bandwidth, and large FSR, suitable for advanced photonic integrated circuits.
  • The demonstrated tunability enables dynamic spectral control, paving the way for reconfigurable optical add-drop multiplexers and tunable filters.
  • Provides a foundation for developing next-generation optical communication and sensing technologies leveraging tunable micro-ring resonators.