32 research outputs found
Ultra-low loss integrated visible photonics using thin-film lithium niobate
Integrated photonics is a powerful platform that can improve the performance
and stability of optical systems, while providing low-cost, small-footprint and
scalable alternatives to implementations based on free-space optics. While
great progress has been made on the development of low-loss integrated
photonics platforms at telecom wavelengths, visible wavelength range has
received less attention. Yet, many applications utilize visible or near-visible
light, including those in optical imaging, optogenetics, and quantum science
and technology. Here we demonstrate an ultra-low loss integrated visible
photonics platform based on thin film lithium niobate on insulator. Our
waveguides feature ultra-low propagation loss of 6 dB/m, while our microring
resonators have an intrinsic quality factor of 11 million, both measured at 637
nm wavelength. Additionally, we demonstrate an on-chip visible intensity
modulator with an electro-optic bandwidth of 10 GHz, limited by the detector
used. The ultra-low loss devices demonstrated in this work, together with the
strong second- and third-order nonlinearities in lithium niobate, open up new
opportunities for creating novel passive, and active devices for frequency
metrology and quantum information processing in the visible spectrum range
Ultrabroadband Nonlinear Optics in Nanophotonic Periodically Poled Lithium Niobate Waveguides
Quasi-phasematched interactions in waveguides with quadratic nonlinearities enable highly efficient nonlinear frequency conversion. In this article, we demonstrate the first generation of devices that combine the dispersion-engineering available in nanophotonic waveguides with quasi-phasematched nonlinear interactions available in periodically poled lithium niobate (PPLN). This combination enables quasi-static interactions of femtosecond pulses, reducing the pulse energy requirements by several orders of magnitude, from picojoules to femtojoules. We experimentally demonstrate two effects associated with second harmonic generation. First, we observe efficient quasi-phasematched second harmonic generation with <100 fJ of pulse energy. Second, in the limit of strong phase-mismatch, we observe spectral broadening of both harmonics with as little as 2-pJ of pulse energy. These results lay a foundation for a new class of nonlinear devices, in which co-engineering of dispersion with quasi-phasematching enables efficient nonlinear optics at the femtojoule level
Ultrahigh-efficiency wavelength conversion in nanophotonic periodically poled lithium niobate waveguides
Periodically poled lithium niobate (PPLN) waveguides are a powerful platform for efficient wavelength conversion. Conventional PPLN converters, however, typically require long device lengths and high pump powers due to the limited nonlinear interaction strength. Here we use a nanostructured PPLN waveguide to demonstrate an ultrahigh normalized efficiency of 2600%/Wācm^2 for second-harmonic generation of 1.5 Ī¼m radiation, more than 20 times higher than that in state-of-the-art diffused waveguides. This is achieved by a combination of sub-wavelength optical confinement and high-fidelity periodic poling at a first-order poling period of 4 Ī¼m. Our highly integrated PPLN waveguides are promising for future chip-scale integration of classical and quantum photonic systems