(a) Schematic diagram of Ag nanodisks embedded in a-Si waveguide with a cross section of 220 × 400 nm2 sandwiched between two Si3N4 layers of equal thickness of 165 nm. The waveguide sits on top of a copper heat sink. The nanodisks are separated from each other with a center-to-center d = 150 nm. Inset: Ag nanodisk with L = 48 nm, W = 15 nm, and H = 15 nm. (b) Optical absorption spectrum of a single Ag nanodisk in a-Si and average electric field enhancement inside of the Ag nanodisk. (c) Top view of the electric field distribution at λ = 1550 nm around Ag nanodisk (white scale bar dimension = 20 nm). (Credit: Scientific Reports)

(a) Schematic diagram of Ag nanodisks embedded in a-Si waveguide with a cross section of 220 × 400 nm2 sandwiched between two Si3N4 layers of equal thickness of 165 nm. The waveguide sits on top of a copper heat sink. The nanodisks are separated from each other with a center-to-center d = 150 nm. Inset: Ag nanodisk with L = 48 nm, W = 15 nm, and H = 15 nm. (b) Optical absorption spectrum of a single Ag nanodisk in a-Si and average electric field enhancement inside of the Ag nanodisk. (c) Top view of the electric field distribution at λ = 1550 nm around Ag nanodisk (white scale bar dimension = 20 nm). (Credit: Scientific Reports)

As streaming, cloud computing, and big data processing experience growth, faster and more stable connections are needed to meet consumer and business expectations and ensure quicker disaster recovery times. One element with the potential to help meet these demands is the all-optical switch.

“An all-optical switch is a cardinal element of future optoelectronic circuits,” says Jacob B. Khurgin, professor of electrical and computer engineering at Johns Hopkins University. “As any switch, the all-optical one is subject to the trade-off between the speed and the power required to achieve switching. The thermo-optical switch is very efficient as it requires relatively low power for switching, but it is also notoriously slow, operating at switching speeds measured in hundreds of microseconds.”

With faster switching in mind, Professor Khurgin and a team of international researchers have demonstrated a way to increase the switching speed in thermo-optical switches. Their findings have been reported online in Scientific Reports, a Nature publication.

“In this theoretical work, we have shown that when minute metal nanoparticles are incorporated into the thermo-optic material the switching speed increases by as much as five orders of magnitude, reaching tens of picoseconds,” says Khurgin.

Additional researchers include Greg Sun, Department of Engineering at the University of Massachusetts-Boston; Wei Ting Chen and Wei-Yi Tsai, Department of Physics at National Taiwan University; and Din Ping Tsai, Department of Physics at National Taiwan University and the Research Center for Applied Sciences at Academia Sinica.

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