Researchers create novel lithium niobate - silicon nitride laser with low frequency noise and fast wavelength tuning

Scientists at EPFL and IBM have created a breakthrough hybrid integrated tunable laser with low frequency noise and fast wavelength tuning by combining lithium niobate and silicon nitride. Due to its unique combination of properties, the new laser has promising applications in LiDAR, telecommunications, and quantum computing.

Lithium niobate is a material that is often used in optical modulators to regulate the frequency or intensity of light transmitted through the device. It is highly valued for its ability to manage large amounts of optical power and its high "Pokels coefficient". This allows the material to change its optical properties when an electric field is applied to it.

The researchers achieved their breakthrough by combining lithium niobate with silicon nitride, which allowed them to produce a new type of hybrid integrated tunable laser. To do this, the team built an integrated circuit (" photonic integrated circuit ") based on silicon nitride light at EPFL and then glued it together with lithium niobate wafers at IBM.

The chip developed in this study. Source: Grigorii Likhachev (EPFL)

This method results in a laser with low frequency noise (a measure of how stable a laser's frequency is), as well as fast wavelength tuning capabilities -- both good qualities for lasers used in light detection and ranging (LiDAR) applications. They then conducted an optical ranging experiment, using the laser to measure distances with high precision.

In addition to integrated lasers, the hybrid platform has the potential to enable integrated transceivers for telecommunications and microwave-optical sensors for quantum computing.

"What is remarkable about this achievement is that the laser provides both low phase noise and fast tuning at megabhertz per second, which has never been achieved before with this type of chip integrated laser," said Tobias J. Kippenberg, professor at EPFL, who led the project.

The research was supported by grants from the Horizon 2020 Framework Program, the Swiss National Science Foundation and the Air Force Office of Scientific Research.

The chip samples were produced at EPFL's Center for Micro and Nano Technology (CMi) and IBM Research's Binnig and Rohrer Center for Nanotechnology (BRNC).

Source: NetEase