Developing a chip-scale optical clock

Abstract

We report our in-house R&D efforts of designing and developing key integrated photonic devices and technologies for a chip-scale optical oscillator and/or clock. This would provide precision sources to RF-photonic systems. It could also be the basic building block for a photonic technology to provide positioning, navigation, and timing as well as 5G networks. Recently, optical frequency comb (OFC)-based timing systems have been demonstrated for ultra-precision time transfer. Our goal is to develop a semiconductor-based, integrated photonic chip to reduce the size, weight, and power consumption, and cost of these systems. Our approach is to use a self-referenced interferometric locking circuit to provide short-term stabilization to a micro-resonator-based OFC. For long-term stabilization, we use an epsilon-near-zero (ENZ) metamaterial to design an environment-insensitive cavity/resonator, thereby enabling a chipscale optical long-holdover clock. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Evaluating Optical Clock Performance for GNSS Positioning

“…For instance, an indication of its transportability was introduced by the authors of [35], who created a 40 Ca + ion optical clock and achieved 7.3 × 10 −16 stability over 1000 s, whilst [36] established an 87 Sr optical lattice clock in a car trailer set-up and showed 4.1 × 10 −17 stability at a similar averaging time. Lately, Chip-Scale Optical Clock (CSOC) development with integrated photonics has also occurred [37][38][39]. Furthermore, some experiments to test optical clock performance in space scenarios were proposed using a lattice optical clock aboard the International Space Station [40] and a molecular iodine optical clock to be on board the TEXUS 54 sounding rocket to assess the maturity of the clock [41].…”

Response Function of Homodyne Wavelength Difference Stabilization

“…Self-stabilization of optical frequency combs (OFCs) may allow for fully on-chip ultra-low phase noise microwave sources. While fiber-optic demonstrations have previously yielded promising results, on-chip implementation imposes significant restrictions on the architecture [1]. For example, obtaining on-chip OFCs (e.g.…”

“…Previously, we have demonstrated a homodyne selfstabilization scheme to address the lack of frequency-shifting components [1,2]. Meanwhile, a method has also been demonstrated to cancel the fceo-noise by filtering the interferometer output to generate signals corresponding to two distinct wavelengths and subtracting their phases in the electrical domain [3]; we will refer to this method as wavelength difference stabilization (WDS).…”