A new way to trap light

MIT researchers discover a new phenomenon that could lead to new types of lasers and sensors. There are several ways to "trap" a beam of light - usually with mirrors, other reflective surfaces, or high-tech materials such as photonic crystals. But now researchers at MIT have discovered a new method to trap light that could find a wide variety of applications. The new system, devised through computer modeling and then demonstrated experimentally, pits light waves against light waves: It sets up two waves that have the same wavelength, but exactly opposite phases - where one wave has a peak, the other has a trough - so that the waves cancel each other out. Meanwhile, light of other wavelengths (or colors) can pass through freely. The researchers say that this phenomenon could apply to any type of wave: sound waves, radio waves, electrons (whose behavior can be described by wave equations), and even waves in water. The discovery is reported this week in the journal Nature by professors of physics Marin Soljacic and John Joannopoulos, associate professor of applied mathematics Steven Johnson, and graduate students Chia Wei Hsu, Bo Zhen, Jeongwon Lee and Song-Liang Chua.