Laser soliton microcombs heterogeneously integrated on silicon

Xiang, Chao; Liu, Junqiu; Guo, Joel; Chang, Lin; Wang, Rui Ning; Weng, Wenle; Peters, Jonathan D.; Wang, Xie; Zhang, Zeyu; Riemensberger, Johann; Selvidge, Jennifer; Kippenberg, Tobias J.; Bowers, John E.

doi:10.1126/science.abh2076

Cited by 223 publications

(121 citation statements)

References 49 publications

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“…The diagnostic power of our comb breathalyzer can be substantially enhanced by expanding the spectral coverage to detect more molecular species, based on the recent extension of frequency combs towards longer wavelengths 22,23,24,25 . Second, by miniaturization and simplification of the technology, CE-DFCS can become transportable 26,27 and deployed in point-of-care settings with minimal operator training. Finally, alternative AI approaches that use neural networks 28 or weighted analyses with non-classifications might improve the predictive power of spectral analyses.…”

Section: Future Outlookmentioning

confidence: 99%

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

Liang¹,

Chan²,

Toscano³

et al. 2022

Preprint

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Human breath contains hundreds of volatile molecules that can provide powerful, non-intrusive spectral diagnosis of a diverse set of diseases and physiological/metabolic states. To unleash this tremendous potential for medical science, we present a robust analytical method that simultaneously measures tens of thousands of spectral features in each breath sample, followed by efficient and detail-specific multivariate data analysis for unambiguous binary medical response classification. We combine mid-infrared cavity-enhanced direct frequency comb spectroscopy (CE-DFCS), capable of real-time collection of tens of thousands of distinct molecular features at parts-per-trillion sensitivity, with supervised machine learning, capable of analysis and verification of extremely high-dimensional input data channels. Here, we present the first application

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Section: Future Outlookmentioning

confidence: 99%

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

Liang¹,

Chan²,

Toscano³

et al. 2022

Preprint

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“…Such fully adaptive QPM greatly eases the efforts for meeting phasematching condition, posing Si 3 N 4 microresonators as ideal testbeds to investigate various χ (2) nonlinear effects beyond SH generation. Meanwhile, Si 3 N 4 is indisputably one of the most popular platforms for Kerr microcomb research 11,[48][49][50][51][52][53] . The combined χ (2) and χ (3) combs have also been observed in Si 3 N 4 microresonators 54,55 , albeit the presence of χ (2) being attributed to intermodal phasematching.…”

Section: Introductionmentioning

confidence: 99%

Photo-induced cascaded harmonic and comb generation in silicon nitride microresonators

Hu¹,

Nitišs²,

He³

et al. 2022

Preprint

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Silicon nitride (Si 3 N 4 ) is an ever-maturing integrated platform for nonlinear optics. Yet, due to the absence of second-order (χ (2) ) nonlinearity, Si 3 N 4 is mostly considered for third-order (χ (3) ) nonlinear interactions. Recently, this limitation was overcome by optical poling in both Si 3 N 4 waveguides and microresonators via the photogalvanic effect, resulting in the inscription of quasi-phase-matched χ (2) gratings. Here, we report cascaded nonlinear effects in a normal dispersion Si 3 N 4 microresonator with combined χ (2) and χ (3) nonlinearities. We demonstrate that the photo-induced χ (2) grating also provides phasematching for the sum-frequency generation process, enabling the initiation and successive switching of primary combs at pump wavelength. Additionally, the doubly resonant pump and secondharmonic fields allow for cascaded third-harmonic generation, where a secondary optically written χ (2) grating is identified. Finally, we reach a lownoise, broadband microcomb state evolved from the sum-frequency coupled primary comb. These results expand the scope of cascaded effects in χ (2) and χ (3) microresonators.

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“…Silicon nitride (Si 3 N 4 ) photonics adds even more functionality, taking advantage of CMOS compatibility, wide bandgap, and lowloss integrated waveguides [31][32][33]. Si 3 N 4 -based lasers have especially leveraged low-loss [10,11,[34][35][36] and have demonstrated coherence on par with commercial fiber lasers [12]. However, they are ultimately limited by thermo-refractive noise (TRN), which has kept the fractional frequency instability of planar waveguide and solid dielectric resonators above the 10 −13 level typical of quartz oscillators [37].…”

Section: Introductionmentioning

confidence: 99%

Chip-Based Laser with 1 Hertz Integrated Linewidth

Guo¹,

McLemore²,

Xiang³

et al. 2022

Preprint

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Lasers with hertz-level linewidths on timescales up to seconds are critical for precision metrology, timekeeping, and manipulation of quantum systems. Such frequency stability typically relies on bulk-optic lasers and reference cavities, where increased size is leveraged to improve noise performance, but with the trade-off of cost, hand assembly, and limited application environments. On the other hand, planar waveguide lasers and cavities exploit the benefits of CMOS scalability, but are fundamentally limited from achieving hertz-level linewidths at longer times by stochastic noise and thermal sensitivity inherent to the waveguide medium. These physical limits have inhibited the development of compact laser systems with frequency noise required for portable optical clocks that have performance well beyond conventional microwave counterparts. In this work, we break this paradigm to demonstrate a compact, high-coherence laser system at 1548 nm with a 1 s integrated linewidth of 1.1 Hz and fractional frequency instability less than 10 −14 from 1 ms to 1 s. The frequency noise at 1 Hz offset is suppressed by 11 orders of magnitude from that of the free-running diode laser down to the cavity thermal noise limit near 1 Hz 2 /Hz, decreasing to 10 −3 Hz 2 /Hz at 4 kHz offset. This low noise performance leverages wafer-scale integrated lasers together with an 8 mL vacuum-gap cavity that employs micro-fabricated mirrors with sub-angstrom roughness to yield an optical Q of 11.8 billion. Significantly, all the critical components are lithographically defined on planar substrates and hold the potential for parallel high-volume manufacturing, and the total laser system optics can be housed in a 150 mL custom compact module. Consequently, this work provides an important advance towards compact lasers with hertz-level linewidths for applications such as portable optical clocks, low-noise RF photonic oscillators, and related communication and navigation systems.

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Laser soliton microcombs heterogeneously integrated on silicon

Cited by 223 publications

References 49 publications

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

Photo-induced cascaded harmonic and comb generation in silicon nitride microresonators

Chip-Based Laser with 1 Hertz Integrated Linewidth

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