Integration of photonic chips with millimeter-scale atomic,micromechanical,chemical,and biological systems can advance science and enable new miniaturized hybrid devices and technology.Optical interaction via small ev...Integration of photonic chips with millimeter-scale atomic,micromechanical,chemical,and biological systems can advance science and enable new miniaturized hybrid devices and technology.Optical interaction via small evanescent volumes restricts performance in applications such as gas spectroscopy,and a general ability to photonically access optical fields in large free-space volumes is desired.However,conventional inverse tapers and grating couplers do not directly scale to create wide,high-quality collimated beams for low-loss diffraction-free propagation over many millimeters in free space,necessitating additional bulky collimating optics and expensive alignment.Here,we develop an extreme mode converter,which is a compact planar photonic structure that efficiently couples a 300 nm×250 nm silicon nitride high-index single-mode waveguide to a well-collimated near surface-normal Gaussian beam with an≈160μm waist,which corresponds to an increase in the modal area by a factor of>105.The beam quality is thoroughly characterized,and propagation over 4mm in free space and coupling back into a single-mode photonic waveguide with low loss via a separate identical mode converter is demonstrated.To achieve low phase error over a beam area that is>100×larger than that of a typical grating coupler,our approach separates the two-dimensional mode expansion into two sequential separately optimized stages,which create a fully expanded and well-collimated Gaussian slab mode before out-coupling it into free space.Developed at 780 nm for integration with chip-scale atomic vapor cell cavities,our design can be adapted for visible,telecommunication,or other wavelengths.The technique can be expanded to more arbitrary phase and intensity control of both large-diameter,free-space optical beams and wide photonic slab modes.展开更多
The commercialization of atomic technologies requires replacing laboratory-scale laser setups with compact and manufacturable optical platforms.Complex arrangements of free-space beams can be generated on chip through...The commercialization of atomic technologies requires replacing laboratory-scale laser setups with compact and manufacturable optical platforms.Complex arrangements of free-space beams can be generated on chip through a combination of integrated photonics and metasurface optics.In this work,we combine these two technologies using flip-chip bonding and demonstrate an integrated optical architecture for realizing a compact strontium atomic clock.Our planar design includes twelve beams in two co-aligned magneto-optical traps.These beams are directed above the chip to intersect at a central location with diameters as large as 1 cm.Our design also includes two co-propagating beams at lattice and clock wavelengths.These beams emit collinearly and vertically to probe the center of the magneto-optical trap,where they will have diameters of≈100μm.With these devices we demonstrate that our integrated photonic platform is scalable to an arbitrary number of beams,each with different wavelengths,geometries,and polarizations.展开更多
基金support under the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology Center for Nanoscale Science and Technology,Award 70NANB10H193,through the University of Maryland.
文摘Integration of photonic chips with millimeter-scale atomic,micromechanical,chemical,and biological systems can advance science and enable new miniaturized hybrid devices and technology.Optical interaction via small evanescent volumes restricts performance in applications such as gas spectroscopy,and a general ability to photonically access optical fields in large free-space volumes is desired.However,conventional inverse tapers and grating couplers do not directly scale to create wide,high-quality collimated beams for low-loss diffraction-free propagation over many millimeters in free space,necessitating additional bulky collimating optics and expensive alignment.Here,we develop an extreme mode converter,which is a compact planar photonic structure that efficiently couples a 300 nm×250 nm silicon nitride high-index single-mode waveguide to a well-collimated near surface-normal Gaussian beam with an≈160μm waist,which corresponds to an increase in the modal area by a factor of>105.The beam quality is thoroughly characterized,and propagation over 4mm in free space and coupling back into a single-mode photonic waveguide with low loss via a separate identical mode converter is demonstrated.To achieve low phase error over a beam area that is>100×larger than that of a typical grating coupler,our approach separates the two-dimensional mode expansion into two sequential separately optimized stages,which create a fully expanded and well-collimated Gaussian slab mode before out-coupling it into free space.Developed at 780 nm for integration with chip-scale atomic vapor cell cavities,our design can be adapted for visible,telecommunication,or other wavelengths.The technique can be expanded to more arbitrary phase and intensity control of both large-diameter,free-space optical beams and wide photonic slab modes.
文摘The commercialization of atomic technologies requires replacing laboratory-scale laser setups with compact and manufacturable optical platforms.Complex arrangements of free-space beams can be generated on chip through a combination of integrated photonics and metasurface optics.In this work,we combine these two technologies using flip-chip bonding and demonstrate an integrated optical architecture for realizing a compact strontium atomic clock.Our planar design includes twelve beams in two co-aligned magneto-optical traps.These beams are directed above the chip to intersect at a central location with diameters as large as 1 cm.Our design also includes two co-propagating beams at lattice and clock wavelengths.These beams emit collinearly and vertically to probe the center of the magneto-optical trap,where they will have diameters of≈100μm.With these devices we demonstrate that our integrated photonic platform is scalable to an arbitrary number of beams,each with different wavelengths,geometries,and polarizations.
