IndiaNanoResearchers(INR)

In a major breakthrough for optoelectronics, researchers at Columbia University have made the smallest yet integrated photonic circuit. In the process, they have managed to attain a high level of performance over a broad wavelength range, something not previously achieved. The researchers believe their discovery is equivalent to replacing vacuum tubes in computers with semiconductor transistors—something with the potential to completely transform optical communications and optical signal processing. The research community has been feverishly trying to build i ntegrated photonic circuits  that can be shrunk to the size of integrated circuits (ICs) used in computer chips. But there’s a big problem: When you use wavelengths of light instead of electrons to transmit information, you simply can’t compress the wavelengths enough to work in these smaller chip-scale dimensions. In research described in the journal  Nature Nanotechnology , the integrated ...

Through advanced calculations physicists and mathematicians have discovered that a thin, diamond-like photonic nanostructure reflects a surprisingly broad range of colors of light, from all angles. This causes the material to have great potential as a back reflector to enhance the efficiency of solar cells or tiny on-chip light sources. The efficiency of solar cells depends on trapping and absorbing light and can be increased by using a back reflector: a mirror behind the solar cell material that reflects light that was not absorbed and leads it back into the solar cell. The ideal mirror reflects light incident from any angle, known as omnidirectional reflectance, and for all frequencies (or colors) of light. Such omnidirectional reflectance for dielectric structures is associated with three-dimensional photonic crystal nanostructures that sustain a so-called complete photonic band gap. However, researchers always thought such structures would have a narrow frequency range of o...