Integrated Silicon Nitride Photonic Chips

Integrated silicon nitride photonic chips with meter-long spiral waveguides. Credit: Jijun He, Junqiu Liu (EPFL)

Encoding data into gentle, and transmitting it via optical fibers lies on the core of optical communications. With an extremely low lack of 0.2 dB/km, optical fibers produced from silica have laid the foundations of right this moment’s international telecommunication networks and our data society.

Such ultralow optical loss is equally important for built-in photonics, which allow the synthesis, processing and detection of optical alerts utilizing on-chip waveguides. Today, plenty of modern applied sciences are primarily based on built-in photonics, together with semiconductor lasers, modulators, and photodetectors, and are used extensively in information facilities, communications, sensing and computing.

Integrated photonic chips are normally produced from silicon that’s plentiful and has good optical properties. But silicon can’t do the whole lot we want in built-in photonics, so new materials platforms have emerged. One of those is silicon nitride (Si3N4), whose exceptionally low optical loss (orders of magnitude decrease than that of silicon), has made it the fabric of alternative for purposes for which low loss is crucial, akin to narrow-linewidth lasers, photonic delay strains, and nonlinear photonics.

Now, scientists within the group of Professor Tobias J. Kippenberg at EPFL’s School of Basic Sciences have developed a brand new expertise for constructing silicon nitride built-in photonic circuits with document low optical losses and small footprints. The work is revealed in Nature Communications.

Combining nanofabrication and materials science, the expertise relies on the photonic Damascene course of developed at EPFL. Using this course of, the workforce made built-in circuits of optical losses of just one dB/m, a document worth for any nonlinear built-in photonic materials. Such low loss considerably reduces the facility price range for constructing chip-scale optical frequency combs (“microcombs”), utilized in purposes like coherent optical transceivers, low-noise microwave synthesizers, LiDAR, neuromorphic computing, and even optical atomic clocks. The workforce used the brand new expertise to develop meter-long waveguides on 5×5 mm2 chips and high-quality-factor microresonators. They additionally report excessive fabrication yield, which is important for scaling as much as industrial manufacturing.

“These chip devices have already been used for parametric optical amplifiers, narrow-linewidth lasers and chip-scale frequency combs,” says Dr. Junqiu Liu who led the fabrication at EPFL’s Center of MicroNanoTechnology (CMi). “We are also looking forward to seeing our technology being used for emerging applications such as coherent LiDAR, photonic neural networks, and quantum computing.”

Reference: “High-yield, wafer-scale fabrication of ultralow-loss, dispersion-engineered silicon nitride photonic circuits” by J. Liu, G. Huang, R. N. Wang, J. He, A. S. Raja, T. Liu, N. J. Engelsen and T. J. Kippenberg, 16 April 2021, Nature Communications.
DOI: 10.1038/s41467-021-21973-z

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