The University of California has developed a pioneering chip that can simultaneously carry lasers and photonic waveguides

A team of computer and electrical engineers at UC Santa Barbara, in collaboration with several colleagues at Caltech and another colleague at Anello Photonics, has developed a first-of-its-kind chip that can carry both laser and photonic waveguides. In a paper published in the journal Nature, the team describes how they made the chip and how it worked during testing.

With the advent of integrated circuits, scientists learned to place transistors, diodes, and other components on a single chip, greatly increasing their potential. In the past few years, researchers working on photonics have hoped to achieve the same feat. People in the field say that the development of similar photonic chips could lead to more precise experiments with atomic clocks and could also be used for quantum applications. It will also reduce the need for huge optical platforms.

In order for such a chip to work, it must house both the laser and the photon waveguide. For this purpose, engineers have developed plug-in isolators to prevent reflections and thus avoid instability in the absence of plug-in isolators. Unfortunately, this method requires the use of magnetism, which causes problems in production. In this new effort, the research team found a way to overcome these problems and create the first truly usable composite chip.

To make the chip, the researchers first placed ultra-low loss silicon nitride waveguides on a silicon substrate. They then covered the waveguide with a variety of silicon and installed a low-noise indium phosphate laser on the waveguide. By separating the two components, the team prevented damage to the waveguide during etching.

The team notes that separating the two components also requires the use of a redistribution layer made of silicon nitride to allow interaction between the two components via the evanescent field. The distance formed by the silicon layer between the two components minimizes interference.

The researchers first measured its noise levels to test their chip. They found they were satisfied and then used it to create a tunable microwave frequency generator. They describe their chip as "a critical step toward complex systems and networks on silicon."

Source: Laser Network