Abstract
Titanium:sapphire (Ti:sapphire) lasers have been essential for advancing fundamental research and technological applications, including the development of the optical frequency comb1, two-photon microscopy2 and experimental quantum optics3,4. Ti:sapphire lasers are unmatched in bandwidth and tuning range, yet their use is restricted because of their large size, cost and need for high optical pump powers5. Here we demonstrate a monocrystalline titanium:sapphire-on-insulator (Ti:SaOI) photonics platform that enables dramatic miniaturization, cost reduction and scalability of Ti:sapphire technology. First, through the fabrication of low-loss whispering-gallery-mode resonators, we realize a Ti:sapphire laser operating with an ultralow, sub-milliwatt lasing threshold. Then, through orders-of-magnitude improvement in mode confinement in Ti:SaOI waveguides, we realize an integrated solid-state (that is, non-semiconductor) optical amplifier operating below 1 μm. We demonstrate unprecedented distortion-free amplification of picosecond pulses to peak powers reaching 1.0 kW. Finally, we demonstrate a tunable integrated Ti:sapphire laser, which can be pumped with low-cost, miniature, off-the-shelf green laser diodes. This opens the doors to new modalities of Ti:sapphire lasers, such as massively scalable Ti:sapphire laser-array systems for several applications. As a proof-of-concept demonstration, we use a Ti:SaOI laser array as the sole optical control for a cavity quantum electrodynamics experiment with artificial atoms in silicon carbide6. This work is a key step towards the democratization of Ti:sapphire technology through a three-orders-of-magnitude reduction in cost and footprint and introduces solid-state broadband amplification of sub-micron wavelength light.
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The data used to support the findings in this work are presented in the main text and Supplementary Information.
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Acknowledgements
We thank C. Langrock for his help with lapping and polishing, K. Yang for the discussions and guidance on fibre tapering, L. Mandyam for technical support in device fabrication and M. M. Fejer for access to laboratory equipment. We acknowledge funding support from the IET A. F. Harvey Prize, the Vannevar Bush Faculty Fellowship from the US Department of Defense, DARPA LUMOS and the AFOSR under award no. FA9550-23-1-0248. J.Y. acknowledges support from the National Defense Science and Engineering Graduate (NDSEG) Fellowship. K.V.G. acknowledges support from the Research Foundation—Flanders (12ZB520N). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF)/Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under award no. ECCS-2026822.
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J.Y. and K.V.G. designed the devices. J.Y., K.V.G., D.M.L. and G.H.A. fabricated the devices. J.Y., K.V.G., D.M.L., M.A.G. and A.D.W. ran the device simulations. J.Y., K.V.G., D.M.L., M.A.G. and A.D.W. assisted with the experimental setup. J.Y., K.V.G., D.M.L. and M.A.G. conducted the measurements on the microdisk lasers. J.Y., K.V.G., D.M.L. and M.A.G. conducted the measurements on the waveguide amplifiers. J.Y., K.V.G. and D.M.L. conducted the measurements on the waveguide lasers. J.Y. and D.M.L. conducted the cavity QED experiment. J.Y., K.V.G. and D.M.L. analysed the data. All authors helped with editing the Article. J.V. supervised the work.
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J.Y. and D.M.L. are cofounders of Brightlight Photonics, which is commercializing integrated Ti:sapphire lasers. K.V.G. is an advisor to Brightlight Photonics. J.Y., K.V.G. and D.M.L. hold equity in Brightlight Photonics. J.V., D.M.L., M.A.G. and G.H.A. are coinventors on a patent application related to integrated Ti:sapphire lasers (patent no. WO 2021/022188). J.V., J.Y., K.V.G. and D.M.L. are coinventors on a patent application related to integrated Ti:sapphire amplifiers.
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Extended Data Fig. 1 Diode-pumped on-chip Ti:Sapphire laser.
(a) Diagram of the measurement setup used in the diode-pumping experiments (MM: multi-mode, OSA: optical spectrum analyzer). (b) Measured optical spectrum of single-mode lasing at 848.7 nm and 858.3 nm, with a SMSR of 23.2 dB and 22.2 dB, respectively. (Inset) Image of the diode package used in these experiments.
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Yang, J., Van Gasse, K., Lukin, D.M. et al. Titanium:sapphire-on-insulator integrated lasers and amplifiers. Nature 630, 853–859 (2024). https://doi.org/10.1038/s41586-024-07457-2
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DOI: https://doi.org/10.1038/s41586-024-07457-2
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