Due to breakthroughs in microchip photonics, microwave signals have now become very accurate

Zhao Yun/Columbia Engineering Company provided an advanced schematic of a photonic integrated chip, which aims to convert high-frequency signals into low-frequency signals using all optical frequency division.

Scientists have built a small all optical device with the lowest microwave noise ever recorded on integrated chips.

In order to improve the performance of electronic devices used for global navigation, wireless communication, radar, and precise timing, reliable microwave sources must be used as clocks and information carriers. To achieve this, it is necessary to minimize phase change noise or random fluctuations to the greatest extent possible.

David M. Rickey, Professor of Applied Physics and Materials Science and Professor of Electrical Engineering at Columbia Institute of Engineering, Alexander Gaeta, reported that a technology called optical frequency division has produced the lowest noise microwave signal in the past decade.
Optical frequency division is the latest innovation used to generate low signal strength microwaves, but its low noise level makes it unsuitable for small sensing and communication applications that require more compact microwave sources.

Gaeta announced that they have created a device that can accurately achieve optical frequency division on a chip using a single laser in a space as small as 1 mm2. This is a breakthrough that simplifies device design.
Gaeta's team focuses on quantum and nonlinear photonics, with a focus on studying the interaction between lasers and matter. The areas of interest include nonlinear nanophotonics, frequency comb generation, ultrafast pulse interactions, and the generation and processing of quantum states of light.
He and his colleagues developed and constructed an all optical on-chip device that uses a silicon nitride microresonator connected by two photons to generate a 16 GHz microwave signal, with frequency noise being the lowest recorded frequency in integrated chip platforms.

The input wave is fed into two micro resonators through a single frequency laser. One of the microresonators is used to generate an optical parametric oscillator, converting the input wave into two output waves of different frequencies. The frequency interval of the new wave is modified to adapt to the terahertz range, and the noise generated by the oscillator can be thousands of times lower than the input laser wave.

This will generate a second microresonator, transforming the optical frequency comb into one of four frequency combs with microwave spacing; Once completed, the optical pulse from the oscillator is fed into the comb generator to synchronize the microwave comb frequency with the terahertz oscillator, synchronizing the two bits and maintaining the optical frequency refractive index.

The research conducted by the Gaeta team demonstrated a simple optical frequency division method that can be carried in small, sturdy, and lightweight boxes. This breakthrough opens up the possibility of chip level technology, which can generate pure and reliable microwave signals similar to those in precision measurement laboratories.

According to his statement, the use of all-optical frequency division can improve the accuracy of microwave radar in autonomous vehicle.
The main idea of this project was proposed by graduate and postdoctoral students Gaeta, Zhao Yun, and Yoshitomo Okawachi. Zhao and Jae Jang subsequently studied these devices and conducted experiments.

This project was developed in close collaboration with Michal Lipson and his team, as well as Cornell University professors Eugene Higgins and Michal Lipson, who were also involved in the construction of photonic chips.

Source: Laser Net