Two-way optical time transfer using a photonic chip
AssigneeVector Atomic, Inc.
InventorsArman Cingoz, Abijith Sudarsan Kowligy, Jonathan David Roslund
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Abstract
Embodiments herein describe sub-picosecond accurate two-way clock synchronization by optically combining received optical pulses with optical pulses generated locally in a photonic chip before the optical signals are then detected by a photodetector to obtain an interference measurement. That is, the optical pulses can be combined to result in different interference measurements. Optically combining the pulses in the photonic chip avoids much of the jitter introduced by the electronics. Further, the sites can obtain multiple interference measurements which can be evaluated to accurately determine when the optical pulses arrive at the site with femtosecond accuracy.
Claims21
A photonic chip comprising:
- a first optical interface for receiving a first pulse train from an external source, wherein the external source comprises a remote clock, wherein pulses in the first pulse train have a first repetition rate;
- a second optical interface configured to receive a second pulse train having pulses with the first repetition rate;
- a timing discriminator configured to:
- receive the first and second pulse trains, and
- generate a control signal to adjust the first repetition rate and a time offset for the second pulse train such that the pulses of the second pulse train are coincident with the pulses of the first pulse train;
- and
- at least one optical interface for outputting an output of the timing discriminator to a photodetector for synchronizing the remote clock to a local clock.
A method, comprising:
- receiving, at a photonic chip, a first pulse train from an external source, wherein the external source comprises a remote clock, wherein pulses in the first pulse train have a first repetition rate;
- receiving, at the photonic chip, a second pulse train having pulses with the first repetition rate;
- controlling, using a timing discriminator in the photonic chip, the first repetition rate and a time offset for the second pulse train such that the pulses of the second pulse train are coincident with the pulses of the first pulse train;
- and
- synchronizing a local clock to the remote clock based on an output of the timing discriminator.
A photonic chip comprising:
- a first optical interface for receiving a first pulse train from an external source, wherein pulses in the first pulse train have a first repetition rate;
- a second optical interface configured to receive a second pulse train having pulses with the first repetition rate;
- a first interferometer configured to receive the first and second pulse trains and delay the first pulse train relative to the second pulse train;
- a second interferometer configured to receive the first and second pulse trains and delay the second pulse train relative to the first pulse train;
- and
- respective optical interferences for outputting respective outputs of the first and second interferometers onto photodiodes.
Dependencies are inferred from the claim text.