Minimizing energy consumption for signal processing using optical microcavities скачать в хорошем качестве

Minimizing energy consumption for signal processing using optical microcavities

Researchers in Takasumi Tanabe's group, at Keio University, are working on achieving signal processing with the lowest possible energy consumption by utilizing photonic technologies. The key device is an optical microcavity, which is a tiny container that can cage photons. When electrons are used for signal processing, the resistance of electrical wiring causes Joule heating, and this means energy is lost. But with photons, this energy loss can be avoided, and so signal processing with high energy efficiency can be achieved. To process optical signals, optical microcavities need to be utilized, these can stop light and allow a strong interaction between light and matter. Q. "The principle of the light confinement in a microcavity that we use is total reflection. This phenomenon is also used in optical fibers that can transmit light over long distances. Total reflection occurs when we have two materials with different refractive indexes, such as glass and air. If light is sent in at an angle, and the incident angle is within a certain value, then all the light is reflected. Ideally, total reflection is lossless, and this means that we can make a very good optical cavity. The light in a toroid microcavity propagates along the side wall, which satisfies the total reflection condition. This means that the light doesn't leak out of the microcavity, and we can confine it for a very long time." In addition to their use for signal processing, microcavities are expected to be employed as sensors for the precise detection of nanometer-sized particles. In this application, the light-confining nature of a resonator is used to detect small particles trapped on its surface. Although a large number of researchers, including the Tanabe group, are using semiconductors and glass to fabricate optical microcavities, researchers in this group are also trying to use crystalline materials to increase the caging time. Q. "Crystalline materials are fragile, so they break very easily. That's the difficulty here. So we're trying to grow crystals in such a way that they will have the desired shape immediately after growth. We're trying to design the shape and grow the crystals at the same time. In this case, we cannot use the conventional semiconductor processes. So we're developing an entirely new fabrication process. For future applications, we'd like to have resonators that have ten or a hundred times stronger confinement than glass ones." Optical microcavities are expected to be used for research on such devices as single-photon transistors, optical ICs, and sensors with extremely high sensitivity. The researchers in Takasumi Tanabe's group are paving the way to the realization of all-optical signal processing at the lowest possible energy, by using photonic and semiconductor micro-fabrication technologies.