Items tagged with "cavity"
Control systems are ubiquitous, and as essential as they are easy to overlook. For instance, turning the dial on a thermostat feels as trivial as moving a piece on a board game, but this control system is actually quite complex.
Can scientists generate any color of light? The answer is not really, but the invention of the laser in 1960 opened new doors for this endeavor. In a result published in Nature Communications scientists* demonstrate a new semiconductor microstructure that performs frequency conversion. This design is a factor of 1000 smaller than previous devices.
Ring resonators are circular waveguides that are used as optical cavities. They look like tiny racetracks and are often fabricated from silicon. Photons can enter and exit a resonator and even move to neighboring waveguides through evanescent coupling. The micro-rings only let light waves circulate-- “resonate”-- if they have the right wavelength. This image, featured on the cover of the December 2013 issue of Nature Photonics, depicts an array of ring resonators designed to be a photonic analog to electrons experiencing quantum Hall physics. Read more to learn more about these micro-racetracks.
Optical cavities can be made by arranging two mirrors facing each other. In this example, light bounces back and forth, forming a standing wave between the mirrors. One of the mirrors is designed to leak out a fraction of the light. Because of the boundaries created by the mirrors, the cavity will only build up light that satisfies a resonance condition--the light's wavelength must be a half-integer multiple of the cavity length. This means that cavities can be used to create narrow frequency sources. Read more to learn more about a cool research result using cavities.