Chinese, U.S. scientists develop tiny, efficient modulator, revolutionize industry

http://www.xinhuanet.com/english/2018-09/24/c_137490235.htm

WASHINGTON, Sept. 24 (Xinhua) -- An international team led by Chinese scientists have built a smaller, more efficient on-chip modulator that is set to revolutionize the communication industry.

The lithium niobate modulator is only 1-2 cm long and its surface area is less than 1 percent of traditional ones, according to a study published Monday in the journal Nature.

Electro-optic modulators are critical components in modern communications, converting high-speed electronic signals in computational devices such as computers to optical signals before transmitting them through optical fibers.

However, the existing and commonly used lithium niobate modulators require a high drive voltage of 3-5V, significantly higher than 1V, a voltage provided by a typical CMOS (complementary metal-oxide-semiconductor) circuitry. Therefore, an electrical amplifier makes the whole device bulky, expensive and energy-consuming.

Scientists from the City University of Hong Kong, Harvard University and Nokia Bell Labs used nano fabrication approaches to build a lithium niobate modulator that can be operated at ultra-high electro-optic bandwidths with a voltage compatible with CMOS.

Its data bandwidth triples from 35 GHz to 100 GHz, but with less energy consumption and ultra-low optical losses.

The tiny modulator can transmit data at rates up to 210 Gbit per second, with about 10 times lower optical losses than existing modulators.

The new invention will pave the way for future high-speed, low power and cost-effective communication networks as well as quantum photonic computation.

"In the future, we will be able to put the CMOS right next to the modulator, so they can be more integrated, with less power consumption. The electrical amplifier will no longer be needed," said Wang Cheng, assistant professor in the Department of Electronic Engineering at City University of Hong Kong and co-first author of the paper.

Wang is looking into its application for the coming 5G communication together with the research team at China's State Key Laboratory of Terahertz and Millimeter Waves at the City University of Hong Kong.

"Millimeter wave will be used to transmit data in free space, but to and from and within base stations, for example, it can be done in optics, which will be less expensive and less lossy," said Wang.