IBM Efficient Silicon Waveguides Could Enable Revolutionary Photonic chips

IBM has created low-loss (0.3% loss over 10 microns) silicon waveguide could enable new photonic chip designs for applications that rely on visible light, and could lead to more efficient lasers and modulators used in telecoms.

Above – Illustration of a pair of silicon high contrast gratings that can be used to guide visible light on a chip with low losses despite large absorption by the silicon material.

Nanostructures were used to make high contrast gratings. Such a grating consists of nanometer-sized ‘posts’ lined up to form a ‘fence’ that prevents light from escaping. The posts are 150 nanometers in diameter and are spaced so that light passing through them interferes destructively with light passing between them. Destructive interference is a phenomenon where waves – including electromagnetic waves such as visible light – that oscillate out of sync cancel each other out. This way, no light can “leak” through the grating and most of it gets reflected back inside the waveguide.

The next step is to engineer the efficient coupling of the light out of the waveguides into other components. That’s a crucial step in our research, with the ultimate goal of integrating the all-optical transistors into integrated circuits that would be able to perform simple logic operations.

Nature Light and Science Applications- Low-loss optical waveguides made with a high-loss material

For guiding light on a chip, it has been pivotal to use materials and process flows that allow low absorption and scattering. Based on subwavelength gratings, here, we show that it is possible to create broadband, multimode waveguides with very low propagation losses despite using a strongly absorbing material. We perform rigorous coupled-wave analysis and finite-difference time-domain simulations of integrated waveguides that consist of pairs of integrated high-index-contrast gratings. To showcase this concept, we demonstrate guiding of visible light in the wavelength range of 550–650 nm with losses down to 6 dB/cm using silicon gratings that have a material absorption of 13,000 dB/cm at this wavelength and are fabricated with standard silicon photonics technology. This approach allows us to overcome traditional limits of the various established photonics technology platforms with respect to their suitable spectral range and, furthermore, to mitigate situations where absorbing materials, such as highly doped semiconductors, cannot be avoided because of the need for electrical driving, for example, for amplifiers, lasers and modulators.

SOURCES – IBM, Nature Light and Science Applications
Written by Brian Wang,

3 thoughts on “IBM Efficient Silicon Waveguides Could Enable Revolutionary Photonic chips”

  1. Excellent point. However, that's partially the point of this story.
    Making tiny waveguides is hardly new. After all, even the omnipresent optical fibre is basically the same thing.
    What this story is about is making a waveguide using silicon chip technology. ie. Using the materials and fabrication technique that we've been using for decades to make billions of highly complex identical objects for a couple of dollars with stunning precision.
    So this is about a step, a big step, on the path to take tiny waveguides from the one-off-in-the-lab stage to the mass production and incorporation into existing products stage.
    Not that they are there yet.

  2. "One of my favorite pastimes is reading science articles detailing the new advances in technology that happen every day in research labs across the world. Usually they say something like “Researchers make new wonder material” or “Researchers find new way to make yyyyy”. The challenge for us as a firm, and me in particular is finding the stories that actually represent an opportunity for commercialization. There are countless materials or devices that are scientifically feasible, but we can’t quite figure out how to make them using existing fabrication techniques. Or maybe we have prototypes that can be made one at a time at a cost of $millions per unit, but there is no practical means to reproduce them in a quantity to allow commercialization…"

    I thought this intro to a recent article on atomically precise manufacturing best characterize these papers. They will be beneficial when other papers solve a thousand other problems preventing progress towards commercialization.

    The side panel of this very blog often showcase old posts of past discoveries promising future possibilities, it's hard to know how many found practical use.
    Yet progress depends on such pursuits, where would we be without all the commercial dead ends.

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