Chip-Scale Packages for a Tunable Wavelength Reference and Laser Cooling Platform

Abstract

We demonstrate a tunable, chip-scale wavelength reference to greatly reduce the complexity and volume of cold-atom sensors. A 1-mm optical path length microfabricated cell provides an atomic wavelength reference, with dynamic frequency control enabled by Zeeman-shifting the atomic transition through the magnetic field generated by the printed-circuit-board coils. The dynamic range of the laser frequency stabilization system is evaluated and used in conjunction with an improved generation of chip-scale coldatom platforms that traps 4 million 87 Rb atoms. The scalability and component consolidation provide a key step forward in the miniaturization of cold-atom sensors.

Silicon-Nitride Photonic Integrated Circuits for Atomic Systems

“…These initial CSACs have limitations with accuracies of ≤ 1 µs per day but optical atomic clock architectures which could be engineered to be chip scale with accuracies of ≤ 1 ns per day have been proposed [3]. To achieve such systems a range of components must be integrated which include narrow-linewidth lasers at specific atomic transitions [4]- [6], spot-size converters (SSC), optical isolators, phase and amplitude modulators, polarizing beam-splitters (PBS) [7], polarization rotators (PR) [7], high-Q micro-resonators [8], miniature frequency combs, grating couplers, photodetectors and MEMS vapour cells [9] to contain the required atomic species.…”

“…Here we present the development of a Si 3 N 4 photonic integrated circuit (PIC) platform [7] [8] suitable for a wide range of thermal and cold atom atomic systems which includes integrated III-V distributed feedback (DFBs) lasers [4]- [6] and Rb MEMS vapour cells [9]. The waveguides are 200 nm thick Si 3 N 4 grown by low pressure chemical vapour deposition deposited on 4 µm thermal SiO 2 with a 1.5 µm plasma enhanced chemical vapour deposition cladding [8].…”

“…Also shown are images of developed components included DFB lasers flip-chip bonded to a Si chip and aligned to SSCs that couple the light into Si 3 N 4 waveguides on the chip, PBS, PR and a MEMS Rb cell which can be wafer bonded to the PIC. The MEMS Rb vapour cells have recently been used to lock lasers enabling chip-scale laser cooling of atoms [9].…”