Related Experiment Video
Updated: Jun 22, 2026
12:18
Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Uniform coil optical resonator and waveguide: transmission spectrum, eigenmodes, and dispersion relation
Optics Express
|June 5, 2009
Summary
The coil optical resonator (COR) traps light through evanescent coupling. Its unique spectrum collapses fractally, revealing distinct waveguide behaviors based on interturn coupling strength.
Area of Science:
- Photonics and Optical Engineering
- Materials Science
- Waveguide Physics
Background:
- The coil optical resonator (COR) is an all-pass optical device formed by tightly winding a microfiber coil on an optical rod.
- Its resonant behavior is governed by evanescent coupling between adjacent microfiber turns.
- Existing resonator and photonic crystal structures exhibit different transmission characteristics.
Purpose of the Study:
- To investigate the transmission characteristics of a uniform coil optical resonator (COR) with N turns.
- To explore the unique resonant behaviors and light-trapping phenomena in CORs.
- To compare COR behavior with established resonator types like SCISSOR and CROW.
Main Methods:
- Theoretical investigation of the uniform COR with N turns.
- Analysis of transmission characteristics based on propagation constant and interturn coupling.
- Examination of spectral properties, including fractal collapse and group velocity zeros.
Main Results:
- Discovered discrete sequences of propagation constant and interturn coupling that enable complete light trapping within the COR.
- Observed a fractal collapse of the COR spectrum for N turns, specifically at points of second-order group velocity zero.
- Demonstrated that COR waveguide behavior transitions from SCISSOR-like (small coupling) to CROW-like (large coupling).
Conclusions:
- The COR exhibits unique transmission characteristics distinct from conventional resonators and photonic crystals.
- Light trapping and fractal spectral collapse are key phenomena in CORs, dependent on coupling and propagation constants.
- CORs offer tunable waveguide functionalities, mimicking SCISSOR and CROW structures based on coupling strength.
Related Concept Videos
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:14Sound Waves: Resonance
Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical boundary conditions (i.e., has a node at each end). A node is defined as a fixed point where the string does not move. The symmetrical boundary conditions result in some frequencies resonating and producing standing waves, while other frequencies interfere destructively. Sound waves can resonate in a hollow tube, and the frequencies of the sound...
01:04Modes of Standing Waves: II
The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions are derived from the physical understanding of how the standing waves are sustained, that is, how the vibrating particles of the medium behave at the boundaries imposed on them.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end.
01:24Electromagnetic Wave Equation
Maxwell's equations for electromagnetic fields are related to source charges, either static or moving. These fields act on a test charge, whose trajectory can thus be determined using suitable boundary conditions. The objective of electromagnetism is thus theoretically complete.
However, although electric and magnetic fields were first introduced as mathematical constructs to simplify the description of mutual forces between charges, a natural question emerges from Maxwell's equations: What...
However, although electric and magnetic fields were first introduced as mathematical constructs to simplify the description of mutual forces between charges, a natural question emerges from Maxwell's equations: What...
01:24Characteristics 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:
01:17Design Example: Underdamped Parallel RLC Circuit
Consider designing an oscillator circuit, a crucial component in various electronic devices and systems. The objective is to create an oscillator circuit with specific characteristics: a damped natural frequency of 4 kHz and a damping factor of 4 radians per second. To accomplish this, a parallel RLC circuit is employed, known for its ability to sustain oscillations at a resonant frequency. In this case, the damping factor is pivotal in achieving the desired performance.
Starting with a fixed...
Starting with a fixed...