Researchers have created a new type of optical device small enough to fit millions on a computer chip that could lead to faster, more powerful information processing and supercomputers.
The "passive optical diode" is made from two tiny silicon rings measuring 10 microns in diameter, or about one-tenth the width of a human hair. Unlike other optical diodes, it does not require external assistance to transmit signals and can be readily integrated into computer chips.
This illustration shows the scheme of a new "silicon passive optical diode". The device has been developed by Purdue University researchers.
The diode is capable of "nonreciprocal transmission," meaning it transmits signals in only one direction, making it capable of better information processing, said Minghao Qi (pronounced Chee), an associate professor of electrical and computer engineering at Purdue University.
Although fiberoptic cables are instrumental in transmitting large quantities of data across oceans and continents, information processing is slowed and the data are susceptible to cyberattack when optical signals must be translated into electronic signals for use in computers.
Electronic diodes constitute critical junctions in transistors and help enable integrated circuits to process information. The new optical diodes are compatible with industry manufacturing processes for complementary metal-oxide-semiconductors, or CMOS, used to produce computer chips.
The new optical diodes could make for faster and more secure information processing by eliminating the need for this translation. The devices, which are nearly ready for commercialization, also could lead to faster, more powerful supercomputers by using them to connect numerous processors together.
Infrared light from a laser goes through an optical fiber and is guided by a microstructure called a waveguide. It then passes sequentially through two silicon rings and undergoes "nonlinear interaction" while inside the tiny rings. Depending on which ring the light enters first, it will either pass in the forward direction or be dissipated in the backward direction, making for one-way transmission. The rings can be tuned by heating them using a "microheater," which changes the wavelengths at which they transmit, making it possible to handle a broad frequency range.
