Modeling photonic device variations Featured

    AIM Photonics Academy summer intern Stuart Daudlin simulates adding a heater to light-filtering ring resonator manufacturing.

    Integrated photonic devices that use light rather than electricity to move and process data can increase speeds and reduce waste heat for computers and networks, but variations in ring resonators, waveguides and other light-filtering devices pose manufacturing challenges. AIM Photonics Academy summer intern Stuart Daudlin is running numerical simulations to identify ways to improve consistency in these photonic products.

    Working under graduate student Germain Martinez, in the lab of Duane Boning, the Clarence J. LeBel Professor of Electrical Engineering at MIT, Daudlin is simulating photonic device manufacturing using a special type of computer software, a finite difference time domain [FDTD] simulator.

    “My goals this summer are to vary the parameters of a ring resonator and define which parameters cause the most variations,” Daudlin explains. “I've built a model for a ring resonator on numerical software, and I have analyzed a few parameters on how the variations might affect the performance of the device. I've had some interesting results so far looking at how only really two parameters stuck out and caused large changes, which is not a good thing, but it's something that we are looking for.” Two factors, the width and the thickness, contributed the most to changes in performance of waveguides and resonators, Daudlin’s simulations show.

    “Variations in silicon photonics are very important,” electrical engineering and computer science graduate student Martinez says, “because the eventual goal would be to implement these structures in the same sort of process that we have to make CMOS [complementary metal-oxide semiconductors], for example, transistors and electronics. The idea would be to have both silicon photonics structures and CMOS structures on the same chip at the same time working together.”

    “CMOS tends to have metal connectors connecting the different transistors together. Those metal interconnects take up a lot of power, they heat up, especially when you are running at gigahertz frequencies,” Martinez says. “One application of silicon photonics would be to replace some of these metal connectors with silicon waveguides, for example, and the benefit of that would be that you don't dissipate nearly as much heat, because you're not heating up metal anymore. You're using light which doesn't heat up.”

    Summer Scholar Stuart Daudlin Screen DP Web
    2017 AIM Photonics Academy summer intern Stuart Daudlin’s project is simulating addition of a heater to light-filtering ring resonator manufacturing. Photo, Denis Paiste, Materials Processing Center.

    Ring resonators and waveguides can play a key role because they can isolate certain wavelengths of light. “Ring resonators directly apply to this data application that Germain was talking about,” Daudlin explains. “They can sort through the wavelengths and essentially modulate the data. That's like what radios do; they modulate a signal.”

    Daudlin is incorporating a heater into his manufacturing simulations. “With a heater or with other ways to actively tune these resonators, you can change what
    wavelengths they let through,” he says. “For a system on a chip, with theoretically a lot of different cores, that would be perfect for routing these cores together. I currently am working at implementing a heater in the device and in my models, so
    I can heat the device, and mitigate these variations and hopefully that will solve these problems in manufacturing.”

    Martinez says the best outcome for the project would be finding the key sensitivities that lead to device variation, showing how to mitigate those sensitivities with the heater and characterizing these results with mathematical models. “If we had a way to generate these things more quickly and with less variations, we could make an entire fiber-optic chip that could handle an entire network and put out a bunch of these at once and save the Internet companies a lot more money and a lot more infrastructure,” he says.

    Daudlin, a University of Michigan, Ann Arbor, engineering physics major, brings to the project his experience with electricity and magnetism, quantum mechanics and radar. “I've learned a lot since I've got here; I've learned how to use all the software,” Daudlin says. “If I can make a mathematical model to describe the variations of these devices, then that would be very useful for the design of these devices.”

    Daudlin’s AIM Photonics Academy internship is part of the “AIM Photonics Future Leaders: Research and Professional Skills Training Program,” with additional support from the Materials Processing Center and the Center for Materials Science and Engineering. AIM Photonics interns from MIT, the University California, Santa Barbara [UCSB], University of Arizona and SUNY Polytechnic Albany convened at UCSB Aug. 10-11, 2017.

    Denis Paiste, Materials Processing Center
    August 28, 2017

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    Summer Scholar Photonics Stuart Daudlin Poster 9251 DP Web
    2017 AIM Photonics Academy summer intern Stuart Daudlin presents his poster on his project is simulating addition of a heater to light-filtering ring resonator manufacturing. Daudlin worked in the lab of Duane Boning, the Clarence J. LeBel Professor of Electrical Engineering at MIT Photo, Denis Paiste, Materials Processing Center.