Rare-earth gain media form the foundation of modern optical communications, emerging quantum hardware, and ultrafast optics. While chip-scale integration can enable fiber-like, and potentially beyond-fiber, functionality with unprecedented scalability, development in the visible and near-infrared remains in its early stages. Here, we demonstrate ytterbium-based optical gain integrated into an aluminum oxide photonic platform, achieving both single-mode lasing and optical amplification in the near-infrared regime. This platform delivers optical amplification with output powers exceeding 0.5 W, an optical-to-optical conversion efficiency above 70

We demonstrate an integrated, ytterbium-based femtosecond pulse amplifier, delivering output peak powers up to 13.85 kW. The pulses generate octave-spanning super-continuum with visible dispersive waves extending from 780 to 500 nm.

The photonics landscape encompasses a wide scope of material platforms, each optimized for specific functionalities, yet no platform meets the demands of all current and evolving photonic applications. Although combining integrated-photonics materials enhances overall capability, such as unifying nonlinear optics, low-loss passive devices and electro-optics, material and process compatibility remains a major challenge. Here we introduce full-wafer, monolithic 3D integration of tantalum pentoxide (Ta2O5, hereafter tantala1) photonics directly onto a patterned substrate, demonstrated here with thin-film lithium niobate2. Tantala's unique properties, importantly room-temperature deposition, moderate-temperature annealing and low residual stress in thick films optimized for phase matching, make it well suited for monolithic 3D integration without compromising substrate performance or compatibility. We demonstrate low-loss, high-quality-factor microresonators and nanophotonics in tantala, robust quasi-phase-matching in poled lithium niobate waveguides3, and efficient 3D interlayer routing. These capabilities enable us to demonstrate a rich palette of nonlinear frequency conversion processes, including χ(3) four-wave mixing for supercontinuum generation, optical parametric oscillation and dark-pulse microcomb generation in tantala microresonators and photonic crystal resonators, χ(2) second-harmonic generation in periodically poled lithium niobate, and combinations thereof.

Optical atomic clocks provide exceptionally accurate and precise signals for timekeeping and precision measurements, but they require high-power, free-space laser configurations that limit scalability. We introduce and explore a scalable infrastructure for strontium (Sr) optical-lattice clocks that incorporates co-design of atomic-beam slowing and a magneto-optical trap (MOT) from an effusion source, generation of complex, three-dimensional free-space laser configurations with a photonic integrated circuit (PIC) and metasurface (MS) optics, and laser stabilization to a frequency-comb supercontinuum generated with integrated nonlinear photonics. With these elements, we realize MOTs of all stable strontium isotopes (^84Sr, ^86Sr, ^87Sr, ^88Sr) with populations commensurate with natural abundances, demonstrating precise beam control and robustness. Access to laser-cooled alkaline-earth atoms with scalable integrated photonics enables system engineering for optical clocks, quantum sensing, and quantum information, and our experiments demonstrate extensible technologies that advance toward a Sr optical clock largely free of bulk optics.

The photonics landscape encompasses a wide scope of material platforms, each optimized for specific functionalities, yet no platform meets the demands of all current and evolving photonic applications. While combining integrated photonics materials enhances overall capability - such as unifying nonlinear optics, low-loss passive devices, and electro-optics - material and process compatibility remains a major challenge. We introduce full-wafer, monolithic 3D integration of tantalum pentoxide (Ta_2O_5, hereafter tantala) photonics onto arbitrary substrates, which we explore here with thin-film lithium niobate (LN) on silicon. Tantala's unique properties, importantly room-temperature deposition, low-temperature annealing, and low stress in thick films optimized for phase matching, make it well suited for monolithic 3D integration without compromising substrate performance or compatibility. We demonstrate low-loss, high-quality-factor microresonators and nanophotonics in tantala, robust quasi-phase-matching in poled LN waveguides, and efficient 3D interlayer routing. This enables us to demonstrate a rich palette of nonlinear frequency conversion processes, including χ^(3) optical parametric oscillation (OPO) and soliton microcomb generation in tantala microresonators and photonic-crystal resonators, χ^(2) second-harmonic generation (SHG) in periodically poled LN, and combinations thereof. Monolithic 3D integration with tantala opens a new paradigm for scalable, multifunctional photonic systems, enabling visible, near-IR, and nonlinear operation into existing photonic infrastructure.

We present a nanophotonic platform of ion-beam-sputtered silica–tantala alloys, where compositional tuning tailors the material linear and nonlinear optical properties, enabling low-loss waveguides for the near-infrared and visible while significantly enhancing the flexibility of photonic design.

We report on experiments generating a magneto-optical trap (MOT) of 88-strontium ($^{88}$Sr) atoms at microkelvin temperature, using integrated-photonics devices. With metasurface optics integrated on a fused-silica substrate, we generate six-beam, circularly polarized, counter-propagating MOTs on the blue broad-line, 461 nm, and red narrow-line, 689 nm, Sr cooling transitions without bulk optics. By use of a diverging beam configuration, we create up to 10 mm diameter MOT beams at the trapping location. To frequency stabilize and linewidth narrow the cooling lasers, we use fiber-packaged, integrated nonlinear waveguides to spectrally broaden a frequency comb. The ultra-coherent supercontinuum of the waveguides covers 650 nm to 2500 nm, enabling phase locks of the cooling lasers to hertz level linewidth. Our work highlights the possibility to simplify the preparation of an ultracold 88Sr gas for an optical-lattice clock with photonic devices. By implementing a timing sequence for control of the MOT lasers and the quadrupole magnetic-field gradient, we collect atoms directly from a thermal beam into the blue MOT and continuously cool into a red MOT with dynamic detuning and intensity control. There, the red MOT temperature is as low as $2~{\mu}$K and the overall transfer efficiency up to 16%. We characterize this sequence, including an intermediate red MOT with modulated detuning. Our experiments demonstrate an integrated photonics system capable of cooling alkaline-earth gases to microkelvin temperature with sufficient transfer efficiencies for adoption in scalable optical clocks and quantum sensors.

We present a 3D-monolithic nonlinear photonics platform comprising $\chi^{(3)}$ tantala and $\chi^{(2)}$ lithium niobate. We demonstrate high power second-harmonic-generation > 10 mW on-chip in poled lithium niobate waveguides, dark-solitons in tantala microres-onators, and low-loss 3D-interlayer routing. © 2025 The Author(s)

We present 3D-integrated thin-film lithium niobate and tantala on a common silicon wafer for diverse, high-performance nonlinear optics. We demonstrate χ(2) second-harmonic generation in periodically poled waveguides and χ(3) soliton microcomb formation in high-Q tantala microresonators.

Microresonator frequency combs and their design versatility have revolutionized research areas from data communication to exoplanet searches. While microcombs in the 1550 nm band are well documented, there is interest in using microcombs in other bands. Here, we demonstrate the formation and spectral control of normal-dispersion dark soliton microcombs at 1064 nm. We generate 200 GHz repetition rate microcombs by inducing a photonic bandgap of the microresonator mode for the pump laser with a photonic crystal. We perform the experiments with normal-dispersion microresonators made from Ta2O5 and explore unique soliton pulse shapes and operating behaviors. By adjusting the resonator dispersion through its nanostructured geometry, we demonstrate control over the spectral bandwidth of these combs, and we employ numerical modeling to understand their existence range. Our results highlight how photonic design enables microcomb spectra tailoring across wide wavelength ranges, offering potential in bioimaging, spectroscopy, and photonic-atomic quantum technologies.

We demonstrate a scalable, integrated photonics infrastructure for compact optical clocks. In this alignment-free MOT 88Sr atoms are cooled to 3 µK and loaded into an optical lattice, ready for ultranarrow clock transition interrogation.

Dielectric metasurfaces, composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements, have revolutionized the field of optics by their potential in constructing high-efficiency and multi-functional optoelectronic systems on chip. The performance of a dielectric metasurface is largely determined by its constituent material, which is highly desired to have a high refractive index, low optical loss and wide bandgap, and at the same time, be fabrication friendly. Here, we present a new material platform based on tantalum pentoxide (Ta 2 O 5 ) for implementing high-performance dielectric metasurface optics over the ultraviolet and visible spectral region. This wide-bandgap dielectric, exhibiting a high refractive index exceeding 2.1 and negligible extinction coefficient across a broad spectrum, can be easily deposited over large areas with good quality using straightforward physical vapor deposition, and patterned into high-aspect-ratio subwavelength nanostructures through commonly-available fluorine-gas-based reactive ion etching. We implement a series of high-efficiency ultraviolet and visible metasurfaces with representative light-field modulation functionalities including polarization-independent high-numerical-aperture lensing, spin-selective hologram projection, and vivid structural color generation, and the devices exhibit operational efficiencies up to 80%. Our work overcomes limitations faced by scalability of commonly-employed metasurface dielectrics and their operation into the visible and ultraviolet spectral range, and provides a novel route towards realization of high-performance, robust and foundry-manufacturable metasurface optics.

We demonstrate dark-soliton microcombs in the 1064 nm band, using a nanophotonic bandgap for tunable phase-matching in normal dispersion. Nanophotonic design enables microcomb spectrum tailoring, here with fifty modes at 200 GHz spacing and 10 dB flatness.

We report on a strontium optical clock built with integrated photonics. We implement free-space laser beam control of positioning, pointing, shaping, polarization, and integration with metasurface optics, and laser-frequency absolute stabilization with waveguide supercontinuum generators.

In the past decade, optical orbital angular momentum (OAM) has entered the field of plasmonics in the form of surface-confined vortices, generating vast interest. Here we give an overview of the field, starting with the pioneering analytic and experimental investigations of plasmonic OAM. We describe the advances leading to the study of suboptical cycle dynamics in time-resolved experiments and the investigation of angular momentum light-matter interactions through the mixing of circularly polarized light with plasmonic vortices. We describe how additional degrees of freedom can be controlled with metasurfaces and other design techniques leading to the complete spatial and temporal modularization of surface-confined OAM. We review maturing applications of plasmonic vortices, such as plasmonic tweezers for the selective trapping and rotation of microparticles and broadband multiplexing of angular momentum light beams for high-capacity optical communications. The major advances in the field, from the first observation to complete modularization, position the controlled surface-confined OAM at the forefront of light-matter science.

We demonstrate an alignment-free 87 Sr magneto optical trap with fully integrated multi-color metasurface photonics. We characterize the functionality of these metasurfaces to facilitate laser cooling and trapping for a compact optical clock.

Visible wavelengths of light control the quantum matter of atoms and molecules and are foundational for quantum technologies, including computers, sensors, and clocks. The development of visible integrated photonics opens the possibility for scalable circuits with complex functionalities, advancing both the scientific and technological frontiers. We experimentally demonstrate an inverse design approach based on superposition of guided-mode sources, allowing the generation and full control of free-space radiation directly from within a single 150 nm layer Ta2O5, showing low loss across visible and near-infrared spectra. We generate diverging circularly-polarized beams at the challenging 461 nm wavelength that can be directly used for magneto-optical traps of strontium atoms, constituting a fundamental building block for a range of atomic-physics-based quantum technologies. Our generated topological vortex beams and spatially-varying polarization emitters could open unexplored light-matter interaction pathways, enabling a broad new photonic-atomic paradigm. Our platform highlights the generalizability of nanoscale devices for visible-laser emission and will be critical for scaling quantum technologies.

Controlling visible-laser emission with integrated photonics affects quantum technologies and challenges nanophotonic design and fabrication. Here, we demonstrate a pathway to millimeter-scale beams with versatile polarization, using wrapped lateral propagation via total internal reflection and metasurface optics.

We demonstrate a scalable, integrated photonics infrastructure for optical atomic clocks. We laser cool and trap 4 × 10 5 87 Sr atoms in a magneto-optical trap, using metasurface optics and a compact, single-chamber vacuum system.

We explore photonic-integrated circuits and metasurface optics to generate multiple, large diameter, circularly polarized laser beams for a compact strontium optical clock. We demonstrate an 88 Sr magneto-optical trap with integrated photonics in a liter-scale apparatus.