Microcombs-optical frequency combs generated in microresonators-have advanced tremendously in the past decade,and are advantageous for applications in frequency metrology,navigation,spectroscopy,telecommunications,and...Microcombs-optical frequency combs generated in microresonators-have advanced tremendously in the past decade,and are advantageous for applications in frequency metrology,navigation,spectroscopy,telecommunications,and microwave photonics.Crucially,microcombs promise fully integrated miniaturized optical systems with unprecedented reductions in cost,size,weight,and power.However,the use of bulk free-space and fiber-optic comp on ents to process microcombs has restricted form factors to the table-top.Taking microcomb-based optical frequency synthesis around 1550 nm as our target application,here,we address this challenge by proposing an integrated photonics interposer architecture to replace discrete components by collecting,routing,and interfacing octave-wide microcomb-based optical signals between photonic chiplets and heterogeneously integrated devices.Experimentally,we con firm the requisite performa nee of the individual passive elements of the proposed interposer一octave-wide dichroics,multimode interferometers,and tunable ring filters,and implement the octave-spanning spectral filteri ng of a microcomb,central to the in terposer,using silicon n itride phot onics.Moreover,we show that the thick silicon nitride needed for bright dissipative Kerr soliton generation can be integrated with the comparatively thin silicon nitride interposer layer through octave-bandwidth adiabatic evanescent coupling,indicating a path towards future system-level consolidation.Fin ally,we numerically confirm the feasibility of operating the proposed in terposer synthesizer as a fully assembled system.Our interposer architecture addresses the immediate need for on-chip microcomb processing to successfully miniaturize microcomb systems and can be readily adapted to other metrology-grade applications based on optical atomic clocks and high-precision navigation and spectroscopy.展开更多
Self-referencing turns pulsed laser systems into self-referenced frequency combs.Such frequency combs allow counting of optical frequencies and have a wide range of applications.The required optical bandwidth to imple...Self-referencing turns pulsed laser systems into self-referenced frequency combs.Such frequency combs allow counting of optical frequencies and have a wide range of applications.The required optical bandwidth to implement self-referencing is typically obtained via nonlinear broadening in optical fibers.Recent advances in the field of Kerr frequency combs have provided a path toward the development of compact frequency comb sources that provide broadband frequency combs,exhibit microwave repetition rates and are compatible with on-chip photonic integration.These devices have the potential to significantly expand the use of frequency combs.Yet to date,self-referencing of such Kerr frequency combs has only been attained by applying conventional,fiber-based broadening techniques.Here we demonstrate external broadening-free self-referencing of a Kerr frequency comb.An optical spectrum spanning two-thirds of an octave is directly synthesized from a continuous wave laser-driven silicon nitride microresonator using temporal dissipative Kerr soliton formation and soliton Cherenkov radiation.Using this coherent bandwidth and two continuous wave transfer lasers in a 2f–3f self-referencing scheme,we are able to detect the offset frequency of the soliton Kerr frequency comb.By stabilizing the repetition rate to a radio frequency reference,the self-referenced frequency comb is used to count and track the continuous wave pump laser’s frequency.This work demonstrates the principal ability of soliton Kerr frequency combs to provide microwave-to-optical clockworks on a chip.展开更多
基金the Defense Adva need Research Projects Agency(DARPA-DODOS)NIST-UDiversity of Maryland(70NANB10H193)National Institute of Standards and Technology(NIST-on-a-chip).A.R.and X.L.gratefully ack no wledge support un der the Cooperative Research Agreement between the University of Maryland and NIST-CNST,Award no.70NANB10H193.
文摘Microcombs-optical frequency combs generated in microresonators-have advanced tremendously in the past decade,and are advantageous for applications in frequency metrology,navigation,spectroscopy,telecommunications,and microwave photonics.Crucially,microcombs promise fully integrated miniaturized optical systems with unprecedented reductions in cost,size,weight,and power.However,the use of bulk free-space and fiber-optic comp on ents to process microcombs has restricted form factors to the table-top.Taking microcomb-based optical frequency synthesis around 1550 nm as our target application,here,we address this challenge by proposing an integrated photonics interposer architecture to replace discrete components by collecting,routing,and interfacing octave-wide microcomb-based optical signals between photonic chiplets and heterogeneously integrated devices.Experimentally,we con firm the requisite performa nee of the individual passive elements of the proposed interposer一octave-wide dichroics,multimode interferometers,and tunable ring filters,and implement the octave-spanning spectral filteri ng of a microcomb,central to the in terposer,using silicon n itride phot onics.Moreover,we show that the thick silicon nitride needed for bright dissipative Kerr soliton generation can be integrated with the comparatively thin silicon nitride interposer layer through octave-bandwidth adiabatic evanescent coupling,indicating a path towards future system-level consolidation.Fin ally,we numerically confirm the feasibility of operating the proposed in terposer synthesizer as a fully assembled system.Our interposer architecture addresses the immediate need for on-chip microcomb processing to successfully miniaturize microcomb systems and can be readily adapted to other metrology-grade applications based on optical atomic clocks and high-precision navigation and spectroscopy.
基金supported by the European Space Agency(ESA)contract ESTEC CN 4000108280/12/NL/PAthe Defense Advanced Research Projects Agency(DARPA)contract W911NF-11-1-0202(QuASAR)+4 种基金the Swiss National Science Foundationsupported by the Air Force Office of Scientific Research,Air Force Material Command,under award FA9550-15-1-0099support from the ESA via contract ESTEC CN 4000105962/12/NL/PAsupport by the Marie Curie IIF Fellowshipsupport from the Hasler foundation and support from the‘EPFL Fellows’fellowship program co-funded by Marie Curie,FP7 Grant agreement no.291771。
文摘Self-referencing turns pulsed laser systems into self-referenced frequency combs.Such frequency combs allow counting of optical frequencies and have a wide range of applications.The required optical bandwidth to implement self-referencing is typically obtained via nonlinear broadening in optical fibers.Recent advances in the field of Kerr frequency combs have provided a path toward the development of compact frequency comb sources that provide broadband frequency combs,exhibit microwave repetition rates and are compatible with on-chip photonic integration.These devices have the potential to significantly expand the use of frequency combs.Yet to date,self-referencing of such Kerr frequency combs has only been attained by applying conventional,fiber-based broadening techniques.Here we demonstrate external broadening-free self-referencing of a Kerr frequency comb.An optical spectrum spanning two-thirds of an octave is directly synthesized from a continuous wave laser-driven silicon nitride microresonator using temporal dissipative Kerr soliton formation and soliton Cherenkov radiation.Using this coherent bandwidth and two continuous wave transfer lasers in a 2f–3f self-referencing scheme,we are able to detect the offset frequency of the soliton Kerr frequency comb.By stabilizing the repetition rate to a radio frequency reference,the self-referenced frequency comb is used to count and track the continuous wave pump laser’s frequency.This work demonstrates the principal ability of soliton Kerr frequency combs to provide microwave-to-optical clockworks on a chip.