High quality-factor (Q) optical resonators are a key component for ultra-narrow linewidth lasers, frequency stabilization, precision spectroscopy and quantum applications. Integration in a photonic waveguide platform is key to reducing cost, size, power and sensitivity to environmental disturbances. However, to date, the Q of all-waveguide resonators has been relegated to below 260 Million. Here, we report a Si3N4 resonator with 422 Million intrinsic and 3.4 Billion absorption-limited Qs. The resonator has 453 kHz intrinsic, 906 kHz loaded, and 57 kHz absorption-limited linewidths and the corresponding 0.060 dB m−1 loss is the lowest reported to date for waveguides with deposited oxide upper cladding. These results are achieved through a careful reduction of scattering and absorption losses that we simulate, quantify and correlate to measurements. This advancement in waveguide resonator technology paves the way to all-waveguide Billion Q cavities for applications including nonlinear optics, atomic clocks, quantum photonics and high-capacity fiber communications.
Dispersive Fourier transform imaging is a powerful technique in achieving ultrafast imaging of wide areas. However, system power efficiency is often limited by dispersive components. Here, we demonstrate that a gap-plasmon metasurface (GPM) based blazed grating can be used in dispersive imaging applications to achieve higher power efficiency than conventional gratings. A sub-wavelength GPM-based grating at telecommunication wavelengths has been designed and fabricated. 75.6% power efficiency with ∼0.4°/10 nm spatial dispersion has been measured for TE polarized waves at normal incidence. The fabricated device has been tested in a wide area real-time dispersive imaging system and <300 μm spatial resolution has been demonstrated experimentally.
Narrow linewidth visible light lasers are critical for atomic, molecular and optical (AMO) physics including atomic clocks, quantum computing, atomic and molecular spectroscopy, and sensing. Stimulated Brillouin scattering (SBS) is a promising approach to realize highly coherent on-chip visible light laser emission. Here we report demonstration of a visible light photonic integrated Brillouin laser, with emission at 674 nm, a 14.7 mW optical threshold, corresponding to a threshold density of 4.92 mW μm−2, and a 269 Hz linewidth. Significant advances in visible light silicon nitride/silica all-waveguide resonators are achieved to overcome barriers to SBS in the visible, including 1 dB/meter waveguide losses, 55.4 million quality factor (Q), and measurement of the 25.110 GHz Stokes frequency shift and 290 MHz gain bandwidth. This advancement in integrated ultra-narrow linewidth visible wavelength SBS lasers opens the door to compact quantum and atomic systems and implementation of increasingly complex AMO based physics and experiments.
We demonstrate a novel technique to fabricate sub-micron silicon nitride waveguides using conventional contact lithography with MEMS-grade photomasks. Potassium hydroxide anisotropic etching of silicon facilitates line reduction and roughness smoothing and is key to the technique. The fabricated waveguides is measured to have a propagation loss of 0.8dB/cm and nonlinear coefficient of γ = 0.3/W/m. A low anomalous dispersion of <100ps/nm/km is also predicted. This type of waveguide is highly suitable for nonlinear optics. The channels naturally formed on top of the waveguide also make it promising for plasmonics and quantum efficiency enhancement in sensing applications.
A microelectromechanical systems acceleration latching switch with cylindrical contacts and an easy-latching/difficult-releasing (ELDR) latching mechanism is presented in this paper. The cylindrical contacts can make the switch immune to fabrication imperfections and off-axis shocks and can decrease the contact resistance as well. The ELDR latching mechanism can latch the switch reliably. Moreover, all the contacts and their support beams are separated from the proof mass so as to prevent the contacts from opening due to the impact resulting from the rebound or vibration of the proof mass once the switch is latched. The switch has been fabricated by a two-mask silicon-on-glass process and tested. The measured latching shock is over 4600 g and the response time is less than 0.2 ms. The total on-resistance is less than 3 while the insulation resistance is more than 100 G and the maximum allowable current is up to 130 mA.
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