Color conversion of on-chip photonics to power next-generation computers and quantum networks

by

In the upper device, two coupled resonators form an eight-shaped structure. The input light from the waveguide travels through the resonators, enters as a color and appears as another colour. The lower device uses three paired resonators: a small toroidal resonator, a long elliptical resonator called a racetrack resonator, and a rectangular resonator. As the light speeds around the racetrack resonator, it rolls to higher and higher frequencies, resulting in a shift of up to 120 GHz. Credit: Second Bay Studios/Harvard SEAS

On-chip frequency converters in the gigahertz range can be used in computers and next-generation quantum networks.

The ability to precisely control and change the properties of a photon, including polarization, location in space, and time of arrival, has given rise to a wide range of communication technologies we use today, including the Internet. The next generation of optical technologies, such as quantum optical networks and computers, will require more control over the properties of the photon.

One of the most difficult properties to change is the color of a photon, also known as its frequency, because changing a photon’s frequency means changing its energy.

Today, most frequency shifters are either very inefficient, lose a lot of light in the conversion process, or cannot convert light in the gigahertz range, where the most important frequencies for communications, computing and other applications are located.

Now, researchers from Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed highly efficient on-chip frequency converters that can convert light in the gigahertz frequency range. Frequency shifters can be easily controlled using continuous and mono microwave ovens.

The search was published in temper nature.

“Our frequency shifters could become an essential building block for classical high-speed and large-scale communication systems as well as emerging optical quantum computers,” said Marco Lunar, Professor of Electrical Engineering at Tiantsai Lin and senior author of the research paper.

The paper specifies two types of on-chip frequency switches – one that can mask one color to another, using an offset of a few tens of gigahertz, and one that can sequence several shifts, i.e. an offset of more than 100 gigahertz.

Each device is built on the lithium niobate platform pioneered by Lonar and his lab.

Lithium nubs can efficiently convert electronic signals into an optical one, but many in the field have considered it difficult to operate at small scales. In previous research, Lončar and his team demonstrated a technique for fabricating high-performance lithium niobite microstructures using the standard plasma Etching to physically sculpt microresonators into lithium niobate thin films.

Here, using the same technique, Lunar and his team etched double cyclic resonators and waveguides onto a thin layer of lithium niobate. In the first device, two coupled resonators form an octagon-like structure. The input light from the waveguide travels through the resonators in a figure-eight pattern, entering as one color and appearing as another colour. This device provides high frequency conversions of up to 28GHz with an efficiency of up to 90%. They can also be reconfigured as tunable frequency beam splitters, in which a beam of one frequency is split into two beams of another frequency.

The second device uses three coupled resonators: a small toroidal resonator, a long elliptical resonator called a racetrack resonator, and a rectangular resonator. As the light speeds around the racetrack resonator, it rolls to higher and higher frequencies, resulting in a shift of up to 120 GHz.

“We are able to achieve this magnitude of frequency shift using only a single microwave signal, 30 gigahertz,” said Yaowen Hu, a research assistant at SEAS and first author of the paper. This is a completely new type of optical device. Previous attempts to convert frequencies in magnitudes greater than 100 gigahertz have been very difficult and expensive, and require an equally large microwave signal.”

“This work is made possible by all of the previous developments in the field of integrated lithium-niobate photons,” Lunar said. “The ability to process information in the frequency domain in an efficient, compact and scalable manner has the potential to significantly reduce the expenditures and resource requirements of large-scale optical circuits, including Quantitative StatisticsCommunications, radar, optical signal processing and spectroscopy. “

Reference: “Photovoltaic Frequency Switches and Beam Dividers” By Yawen Hu, Mingye Yu, De Chu, Neil Sinclair, Amir Hassan Shams Ansari, Linbow Shaw, Jeffrey Holzgrave, Eric Boma, Mian Zhang and Marco Lunar, November 24, 2021, temper nature.
DOI: 10.1038 / s41586-021-03999-x

The Harvard Technology Development Office has protected the intellectual property associated with this project and is pursuing commercialization opportunities.

The research was co-authored by Mingye Yu, De Chu, Neil Sinclair, Amir Hassan Shams Ansari, Linbow Shaw, Jeffrey Holzgrave, Eric Boma and Mian Zhang. Supported in part by the United States Office of Naval Research under grant QOMAND N00014-15-1-2761, and the Air Force Office of Scientific Research under grants FA9550‐19‐1‐0310 and FA9550-20-1-0105, National Science Foundation, under grant ECCS-1839197, ECCS-1541959, PFI-TT IIP-1827720, Army Research Office under grant W911NF2010248, and Department of Energy under grant HEADS-QON DE-SC0020376.

Leave a reply:

Your email address will not be published.