Technology has been improving at a quick rate compared to the centuries before; our smartphones have much more power than supercomputers made decades ago. Although this is true, the semiconductor industry has to come up with new ways to improve current technology. We’re reaching the smallest we can make components that make our devices work. One way researchers are looking to innovate is through improving waveguide based systems/platforms.
Waveguides have varying purposes depending on the application they’re fabricated for. For background information, one anecdotal example of their use is detecting refractive index changes. Data dealing with how the material reacts to light is extracted easily, with potential for multiple uses in different fields.
The flexibility of waveguides makes them an appealing choice for optical circuits and electronics. It leads to different research done to improve waveguide efficiency, such as in the main paper of this article. Researchers from two universities (Zhejiang University and Universidad de Málaga) and from the National Research Council in Canada came up with a design to improve a silicon nitride based platform’s grating coupler. Couplers are an important part of the system that couples (transfers) light/energy from one medium to another. Multiple challenges come with alternative designs from the usual platforms, including a lower refractive index. A low refractive index near 1 (similar to that of air) causes the grating to be much weaker than that of its oxide based counterpart (closer to 2.5). This is the main cause of coupling loss in these nitride based systems, making it hard to create effective designs.
To overcome that, they increased the length of the grating without creating coupling loss. What makes this unusual is that there is usually an increase in the loss with an increase in length. Instead, they improved efficiency of the system by utilizing a different technique when creating it. With 86% coupling efficiency, they made a breakthrough in nitride based platforms not seen before. It’s a small step forward, but the results of creating a grating coupler with high efficiency and a low refractive index can lead to future studies that shape the technological future.
Edited by: Ramneet Chauhan