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Abstract: “A novel technique is presented for realising programmable silicon photonic circuits. Once the proposed photonic circuit is programmed, its routing is retained without the need for additional power consumption. This technology enables a uniform multi-purpose design of photonic chips for a range of different applications and performance requirements, as it can be programmed for each specific application after chip fabrication. Therefore the cost per chip can be dramatically reduced because of the increase in production volume, and rapid prototyping of new photonic circuits is enabled. Essential building blocks for programmable circuits, erasable directional couplers (DCs) were designed and fabricated, utilising ion implanted waveguides. We demonstrate permanent switching between the drop port and through port of the DCs using a localised post-fabrication laser annealing process. Proof-of-principle demonstrators in the form of generic 1×4 and 2×2 programmable switching circuits were then fabricated and subsequently programmed, to define their function. “

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    This is a really clever idea. Being able to set an optical switch without continuous power is something I hadn’t seen before. I didn’t follow the all device level details, but then, I worked on a photonics project for five years and I never really did. :)

    I skimmed this to see what the loss numbers for these devices would be - that’s what we usually focused on when trying to design system architectures that would be competitive with electronic networks.

    Looking back at the last paper I was involved in about this 1, it seems like we needed basically every device along a waveguide to have a loss of less than 0.75dB, and for the number of devices along a path to be ten or fewer (IIRC), for a switched optical network to be competitive. It looks like each of these programmable switches has ~2dB loss, so you’d blow your budget pretty quickly.

    Also as an aside, I’m still surprised to read new papers about this kind of stuff that completely omits the work our collaborators were doing (and publishing) at Sun & Oracle. It’s just weird to me. I don’t really recognize these authors but I met many of the people they did cite, and they certainly knew our people.