Counter-propagating solitons in microresonators
Solitons occur in many physical systems when a nonlinearity compensates wave dispersion. Their recently demonstrated formation in microresonators has opened a new research direction for nonlinear optical physics. Soliton mode locking also endows frequency microcombs with the enhanced stability necessary for miniaturization of spectroscopy and frequency metrology systems. These microresonator solitons orbit around a closed waveguide path and produce a repetitive output pulse stream at a rate set by the roundtrip time. Here, counter-propagating solitons that simultaneously orbit in an opposing sense (clockwise/counter-clockwise) are studied. Despite sharing the same spatial mode family, their roundtrip times can be precisely and independently controlled. Furthermore, a state is possible in which both the relative optical phase and relative repetition rates of the distinct soliton streams are locked. This state allows a single resonator to produce dual-soliton frequency-comb streams with different repetition rates, but with a high relative coherence that is useful in both spectroscopy and laser ranging systems.
Additional Information© 2017 Macmillan Publishers Limited, part of Springer Nature. Received 06 February 2017; Accepted 14 June 2017; Published online 07 August 2017. The authors acknowledge the Defense Advanced Research Projects Agency under the PULSE (grant no. W31P4Q-14-1-0001) and SCOUT (contract no. W911NF-16-1-0548) programmes, NASA and the Kavli Nanoscience Institute. Author Contributions: Experiments were conceived by Q.-F.Y., X.Y., K.Y.Y. and K.V. Analysis of results was conducted by Q.-F.Y., X.Y., K.Y.Y. and K.V. Q.-F.Y. and X.Y. performed measurements. K.Y.Y. fabricated devices. All authors participated in writing the manuscript. The authors declare no competing financial interests. Data availability: The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
Submitted - 1704.08409.pdf
Supplemental Material - nphoton.2017.117-s1.pdf