The COVID-19 pandemic has profoundly reshaped the way people live and work, marked by new routines of online teaching and web conferencing. Behind the scenes of all the fancy apps are optical fiber networks that are responsible for transmitting an enormous amount of data. And within the fiber networks, LiNbO3 electro-optic modulators play a crucial role by converting electrical signals to optical signals.
However, these modulators are bulky, expensive, and power-consuming since they are not integrated, and are incompatible with modern semiconductor fabrication processes. A key challenge in miniaturizing LiNbO3 photonic devices lies in the non-trivial micromachining of LiNbO3 material, which often comes with rough sidewalls and prohibitively high optical losses.
Cheng Wang, an assistant professor at the City University of Hong Kong, has been working on miniaturizing LiNbO3 photonic devices for more than 8 years. He has developed a series of high-performance photonic devices, which have low power consumption and small size. Such devices possess great potential in future applications in optical communications and quantum information processing. This result received funds from MIT the Engine. At the end of 2018, Wang and colleagues founded HyperLight and has generated revenues.
During his Ph.D., Wang and his colleagues developed robust and scalable nanofabrication techniques, which could produce LiNbO3 photonic devices with record-low propagation losses. In other words, light could be routed back and forth in his photonic chip for a 1-meter-long distance while losing only half of the power. The results put LiNbO3 as one of the lowest-loss nanophotonic materials while featuring unique electro-optic properties.
In 2018, Wang further combined the low-loss LiNbO3 photonic infrastructure with high-speed microwave designs to realize integrated electro-optic modulators with record performances. The integrated LiNbO3 modulators feature dramatically lowered drive voltages (~ 1V), which are directly compatible with typical CMOS circuitry. As a result, bulky and power-hungry electrical amplifiers that are required for traditional LiNbO3 modulators could be eliminated.
The integrated LiNbO3 platform Wang developed has led to many other high-performance photonic devices, including broadband on-chip electro-optic frequency comb generation and electrically programmable photonic molecules.
At present, Wang has established his research team at the City University of Hong Kong. In the future, he wants to further expand the scale and functional complexity of LiNbO3 photonic chips and strive to explore new technological breakthroughs, and continue to push the results to practical applications.
