GLAss and Rare-Earth Photonic Integration for Quantum and Lasing Applications

Abstract

As integrated photonics advances sensing, precision metrology, and quantum technologies, the integration of novel materials is becoming essential for enabling chip-scale multifunctionality. In GLARE, my research will focus on designing and integrating next-generation photonic systems using rare-earth (RE)-doped materials and specialty glasses, with a particular emphasis on ultrafast laser systems and quantum devices.

Recent breakthroughs have been achieved in the photonic integration of solid-state gain (SSG) materials, including erbium-ion-implanted silicon nitride (Er:Si3N4)[1], thulium-doped alumina (Tm:Al2O3)[2], and titanium-doped sapphire (Ti:sapphire)[3],[4]. These advances have enabled the realization of on-chip solid state lasers (SSLs) and amplifiers with comparable performance of table top systems which surpasses integrated diode-based lasers, in terms of noise and power handling capabilities.[5],[6].

Among various SSG materials, REs are especially suited for laser and quantum technologies because their shielded 4f orbitals provide stable emission lines, long coherence times, narrow linewidths and long coherence times, enabling efficient lasers, quantum memories, and single-photon sources across key spectral ranges from UV to mid-infrared[7]. Furthermore, REs offer high-power scalability and support ultrashort pulse generation, positioning them as key enablers for on-chip high-power and ultrafast laser systems.5,6.

Nevertheless, the spectral coverage of current on-chip SSLs remains limited, primarily spanning 750-950 nm (Ti:sapphire4), 1.5 μm (Er:Si3N4)1, and 2.0 μm (Tm3). Crucial wavelength bands for science and technology are still missing, including the O-band for datacom, the 1.0 μm range for biomedical and environmental sensing, and the visible spectrum for atomic clocks and quantum science, where many transitions of crucial cold atoms (171Yb, 40Ca+, 88Sr ions) reside.

To unlock these wavelength gaps, I will leverage my expertise on RE materials and heterogeneous integration to develop wafer-scale active photonic devices on photonic integrated circuit (PIC) platforms (silicon and silicon nitride). This will involve both monolithic integration, such as sputtering and wet-chemical deposition of RE-doped glasses and glass-ceramics, and heterogeneous integration, including micro-transfer printing of thin-film RE-doped crystals or melt-quenched glasses. It is well known that lasing properties of REs can vary significantly with their surrounding environments, e.g. in glasses, in single-crystals, or glass-ceramics and each material host has to be chosen and engineer suitably for the interest RE type and transition. My near-term objectives include the realization of ytterbium (Yb)-based mode-locked lasers (MLLs) on Si3N4 using sputtered Yb-doped glasses, and praseodymium (Pr)-based MLLs operating in the O-band via micro-transfer printing of Pr-doped crystals onto Si3N4 PICs.

Beyond the RE-based materials, I will build on my experience in glass photonics to integrate specialty active glasses into photonic integrated circuits. For instance, I will explore photosensitive glasses for on-chip reconfigurable structures[8] and highly nonlinear glasses for enhanced frequency conversion and signal processing, thereby extending the functionality of PIC systems.

[1] Liu, Y., Qiu, Z., Ji, X., Lukashchuk, A., He, J., Riemensberger, J., ... & Kippenberg, T. J. (2022). A photonic integrated circuit–based erbium-doped amplifier. Science, 376(6599), 1309-1313.
[2] Singh, N., Lorenzen, J., Wang, K., Gaafar, M. A., Sinobad, M., Francis, H., ... & Kärtner, F. X. (2025). Watt-class silicon photonics-based optical high-power amplifier. Nature Photonics, 19(3), 307-314.
[3] Wang, Y., Holguín-Lerma, J. A., Vezzoli, M., Guo, Y., & Tang, H. X. (2023). Photonic-circuit-integrated titanium: sapphire laser. Nature Photonics, 17(4), 338-345.
[4] Yang, J., Van Gasse, K., Lukin, D. M., Guidry, M. A., Ahn, G. H., White, A. D., & Vučković, J. (2024). Titanium: sapphire-on-insulator integrated lasers and amplifiers. Nature, 630(8018), 853-859.
[5] Singh, N., Lorenzen, J., Sinobad, M., Wang, K., Liapis, A. C., Frankis, H. C., ... & Kärtner, F. X. (2024). Silicon photonics-based high-energy passively Q-switched laser. Nature photonics, 18(5), 485-491.Z. Qiu et al., "High-Energy Mode-Locked Pulses from a Photonic Integrated Mamyshev Oscillator,"
[6] Qiu, Z., Hu, J., Yang, X., Liu, Z., Zhang, Y.,... & Kippenberg, T. (2025). High-pulse-energy integrated mode-locked lasers based on a Mamyshev oscillator. arXiv:2509.05133.
[7] Tran, T. N. L., Szczurek, A., Lukowiak, A., & Chiasera, A. (2022). (Invited) A review on rare-earth activated SnO2-based photonic structures: Synthesis, fabrication and photoluminescence properties. Optical Materials: X, 13, 100140.
[8] Tran, T. N. L., Berneschi, S., Trono, C., Conti, G. N., Zur, L., Armellini, C., ... & Ferrari, M. (2020). SiO2-SnO2: Er3+ planar waveguides: Highly photorefractive glass-ceramics. Optical Materials: X, 7, 100056.