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We demonstrate passive large-scale nanophotonic phased arrays in a CMOS-compatible silicon photonic platform. Silicon nitride waveguides are used to allow for higher input power and lower phase variation compared to a silicon-based distribution network. A phased array at an infrared wavelength of 1550 nm is demonstrated with an ultra-large aperture size of 4  mm×4  mm, achieving a record small and near diffraction-limited spot size of 0.021°×0.021° with a side lobe suppression of 10 dB. A main beam power of 400 mW is observed. Using the same silicon nitride platform and phased array architecture, we also demonstrate, to the best of our knowledge, the first large-aperture visible nanophotonic phased array at 635 nm with an aperture size of 0.5  mm×0.5  mm and a spot size of 0.064°×0.074°.

Gravity gradients represent a major obstacle in high-precision measurements by atom interferometry. Controlling their effects to the required stability and accuracy imposes very stringent requirements on the relative positioning of freely falling atomic clouds, as in the case of precise tests of Einstein's equivalence principle. We demonstrate a new method to exactly compensate the effects introduced by gravity gradients in a Raman-pulse atom interferometer. By shifting the frequency of the Raman lasers during the central π pulse, it is possible to cancel the initial position- and velocity-dependent phase shift produced by gravity gradients. We apply this technique to simultaneous interferometers positioned along the vertical direction and demonstrate a new method for measuring local gravity gradients that does not require precise knowledge of the relative position between the atomic clouds. Based on this method, we also propose an improved scheme to determine the Newtonian gravitational constant G towards the 10 ppm relative uncertainty.

Silicon photonics has been heralded for a number of high technology fields, but access to a high quality technology has been limited to vertically integrated design/fabrication companies, or fabless companies with significant resources to engage high volume fabs. More recently, research and development hubs have developed and released process design kits and multi-project wafer programs to lower the barrier. We present the first silicon photonics multi-project wafer (MPW) service produced in a state-of-the-art 300 mm fabrication facility. The MPW service is enabled by a best-in-class process design kit (PDK) which allows designers to layout and obtain photonic integrated circuits (PICs) that work properly on the first run. The fabrication of these circuits is carried out at the SUNY Polytechnic Institute which operates a world class 300 mm cleanroom that, besides silicon photonics, develops sub-7 nm CMOS architectures. The industrial-level management of this facility and its equipment provides high quality photonic devices which are repeatable from run-to-run along with rapid turnaround time. The devices that are available to designers via the process design kit are produced by Analog Photonics and have been verified on actual runs. The performance of these devices is comparable to the state-of-the-art and enables a wide variety of silicon photonic applications. Index Terms-Photonic integrated circuits, silicon photonics, foundries. I. INTRODUCTION O VER the past twenty years the popularity of silicon photonic integrated circuits (PICs) has increased as their reported performance improves. This popularity is partially driven due to the potential cost benefits that silicon-based PICs possess over alternative material platforms (ie, III-V). Specifically, PICs fabricated using a silicon-based platform are able to take advantage of the unsurpassed infrastructure of silicon-based electronic Manuscript

We demonstrate monolithic 160-µm-diameter rare-earth-doped microring lasers using silicon-compatible methods. Pump light injection and laser output coupling are achieved via an integrated silicon nitride waveguide. We measure internal quality factors of up to 3.8 × 105 at 980 nm and 5.7 × 105 at 1550 nm in undoped microrings. In erbium- and ytterbium-doped microrings we observe single-mode 1.5-µm and 1.0-µm laser emission with slope efficiencies of 0.3 and 8.4%, respectively. Their small footprints, tens of microwatts output powers and sub-milliwatt thresholds introduce such rare-earth-doped microlasers as scalable light sources for silicon-based microphotonic devices and systems.