by Clarence Oxford
Los Angeles CA (SPX) Apr 29, 2026
Researchers at Harvard have demonstrated a chip-scale ultraviolet mild supply constructed on thin-film lithium niobate that generates 4.2 milliwatts of on-chip UV energy at 390 nanometers wavelength — roughly 120 instances extra output energy than any earlier comparable demonstration on the identical materials platform.
Ultraviolet mild is used throughout a variety of recent purposes, from floor disinfection and fluorescence imaging of organic supplies to photolithography in semiconductor manufacturing. On the chip scale, compact UV sources are anticipated to allow advances in trapped-ion quantum computer systems, ultra-precise atomic clocks, and compact environmental sensors able to monitoring greenhouse gases and atmospheric pollution.
The core problem has been that UV mild loses energy quickly because it travels by way of optical waveguides, making it extraordinarily troublesome to construct sensible chip-scale sources at these wavelengths. The Harvard staff, working within the lab of Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering, addressed this by changing crimson mild to UV mild straight on the chip slightly than trying to ship UV mild from an exterior supply.
Within the frequency upconversion course of utilized by the machine, two crimson photons mix contained in the lithium niobate crystal to supply a single higher-energy UV photon. Lithium niobate is already a well-established platform for built-in photonics, notably at infrared and telecommunications wavelengths, however this work demonstrates it may well additionally information and host mild sources at a lot shorter UV wavelengths.
“When individuals take into consideration [thin-film lithium niobate], they do not consider it as a UV materials, however we present that it’s,” stated co-first writer Kees Franken, a former analysis fellow within the Loncar lab. “We additionally present that there are another nonlinear results occurring that we do not totally perceive but.”
Environment friendly frequency conversion in lithium niobate requires a nanofabrication course of referred to as poling, during which the crystal grain constructions are periodically flipped at exactly managed intervals alongside the waveguide. Getting that periodic sample precisely proper — at sub-micron size scales over centimeter-long gadgets — has been the central limitation of earlier makes an attempt.
Earlier fabrication approaches confronted a basic tradeoff. Poling your entire movie earlier than etching the waveguides preserved poling high quality however eradicated the flexibility to compensate for fabrication imperfections. Fabricating waveguides first after which poling allowed corrections, however the electrodes needed to be positioned removed from the waveguide, leading to solely partial poling of the movie and lowered conversion effectivity.
The Harvard staff invented a brand new method they name sidewall poling to resolve this tradeoff. Slightly than inserting electrodes solely above the movie, they patterned metallic electrodes — formed as slender metallic fingers — straight in opposition to the sidewalls of the etched waveguide, requiring positioning accuracy of roughly 50 nanometers.
“The important thing concept was: may we simply put the electrodes straight on the waveguide?” stated co-first writer Soumya Ghosh, a former graduate scholar within the lab. Putting electrodes on the sidewalls allowed the researchers to totally invert the crystal domains throughout your entire waveguide cross-section, so that every one the sunshine passing by way of the machine sees a uniformly flipped materials construction. This maximizes conversion effectivity all through the waveguide.
The geometry additionally allowed the staff to tailor the poling interval alongside the size of the machine, drawing on tailored poling methods beforehand developed by the Loncar group and others, to compensate for variations in movie thickness and waveguide form which can be unavoidable in cleanroom fabrication.
Earlier thin-film lithium niobate demonstrations at this wavelength vary produced solely tens of microwatts of UV energy — sufficient to determine feasibility however far beneath the edge for sensible purposes. The brand new machine’s 4.2 milliwatt output represents a step towards real-world usefulness.
Trapped-ion quantum computer systems require exactly managed UV mild at wavelengths akin to particular atomic transitions, and scaling these methods right down to chip-level parts is taken into account important for making the expertise sensible. “If you would like a scalable quantum pc that is not the dimension of a truck, you want to scale all the pieces right down to the chip stage, and this consists of the sunshine sources,” Franken stated.
Ghosh and Franken attributed the advance partly to the Loncar lab’s built-in method to analysis, combining theoretical design, cleanroom fabrication, and optical characterization inside a single group. “The hands-on instinct that we gained for learn how to make a tool, whereas additionally maintaining the zoomed-out view of what this machine is for, and the way we had been going to characterize it — that is an enormous a part of what enabled this venture for us,” Ghosh stated.
The paper was co-authored by C.C. Rodrigues, J. Yang, C.J. Xin, S. Lu, D. Witt, G. Joe, G.S. Wiederhecker, and Ok.-J. Boller. Funding got here from the Division of the Air Power, the Workplace of Naval Analysis, NASA, and the Nationwide Science Basis.
Analysis Report:Milliwatt-level UV technology utilizing sidewall poled lithium niobate
Associated Hyperlinks
Harvard Faculty of Engineering and Utilized Sciences
Laptop Chip Structure, Know-how and Manufacture
Nano Know-how Information From SpaceMart.com
