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11:08
Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities
Published on: November 30, 2012
Demonstration of a cavity coupler based on a resonant waveguide grating
Frank Brückner1, Daniel Friedrich, Tina Clausnitzer
1Institut für Angewandte Physik, Friedrich-Schiller-Universität Jena, Jena, Germany. frank.brueckner@uni-jena.de
Optics Express
|January 9, 2009
Summary
Researchers developed a novel cavity coupler using a guided-mode resonant grating to reduce thermal noise in optical coatings. This innovation is crucial for enhancing the sensitivity of gravitational wave detectors and quantum experiments.
Area of Science:
- Optics
- Materials Science
- Quantum Physics
Background:
- Thermal noise in optical coatings limits sensitivity in gravitational wave detectors and quantum experiments.
- Reducing mechanical loss in dielectric coatings is key to mitigating thermal noise.
Purpose of the Study:
- To experimentally realize and characterize a novel cavity coupler based on a surface relief guided-mode resonant grating.
- To decrease the thickness of dielectric coatings, thereby reducing mechanical loss and thermal noise.
Main Methods:
- Fabrication of a surface relief guided-mode resonant grating cavity coupler.
- Integration of the coupler into a Fabry-Perot resonator with a conventional high-quality mirror.
- Measurement of the cavity finesse and calculation of the coupler reflectivity.
Main Results:
- The cavity coupler was successfully realized and characterized.
- The Fabry-Perot resonator achieved a finesse of F = 657.
- The coupler reflectivity was determined to be R = 99.08 %.
Conclusions:
- The novel cavity coupler demonstrates potential for significantly reducing thermal noise.
- This technology can enhance the sensitivity of gravitational wave detectors and advance quantum experiments.
- The reduced coating thickness offers a promising path towards lower mechanical loss in optical systems.
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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:
01:24Characteristics 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: