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347 results on '"Kippenberg, Tobias J."'

28. Difference-frequency generation in optically poled silicon nitride waveguides

Author

Sahin Ezgi, Zabelich Boris, Yakar Ozan, Nitiss Edgars, Liu Junqiu, Wang Rui N., Kippenberg Tobias J., and Brès Camille-Sophie

Subjects
all-optical poling, difference-frequency generation, integrated optics, second-order nonlinearity, Physics, QC1-999
Abstract

Difference-frequency generation (DFG) is elemental for nonlinear parametric processes such as optical parametric oscillation and is instrumental for generating coherent light at long wavelengths, especially in the middle infrared. Second-order nonlinear frequency conversion processes like DFG require a second-order susceptibility χ (2), which is absent in centrosymmetric materials, e.g. silicon-based platforms. All-optical poling is a versatile method for inducing an effective χ (2) in centrosymmetric materials through periodic self-organization of charges. Such all-optically inscribed grating can compensate for the absence of the inherent second-order nonlinearity in integrated photonics platforms. Relying on this induced effective χ (2) in stoichiometric silicon nitride (Si3N4) waveguides, second-order nonlinear frequency conversion processes, such as second-harmonic generation, were previously demonstrated. However up to now, DFG remained out of reach. Here, we report both near- and non-degenerate DFG in all-optically poled Si3N4 waveguides. Exploiting dispersion engineering, particularly rethinking how dispersion can be leveraged to satisfy multiple processes simultaneously, we unlock nonlinear frequency conversion near 2 μm relying on all-optical poling at telecommunication wavelengths. The experimental results are in excellent agreement with theoretically predicted behaviours, validating our approach and opening the way for the design of new types of integrated sources in silicon photonics.

Published
2021
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30. Controlling free electrons with optical whispering-gallery modes

Author

Kfir, Ofer, Lourenço-Martins, Hugo, Storeck, Gero, Sivis, Murat, Harvey, Tyler R., Kippenberg, Tobias J., and Feist, Armin

Subjects
Electron microscopy -- Methods, Electrons -- Optical properties -- Methods, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Free-electron beams are versatile probes of microscopic structure and composition.sup.1,2, and have revolutionized atomic-scale imaging in several fields, from solid-state physics to structural biology.sup.3. Over the past decade, the manipulation and interaction of electrons with optical fields have enabled considerable progress in imaging methods.sup.4, near-field electron acceleration.sup.5,6, and four-dimensional microscopy techniques with high temporal and spatial resolution.sup.7. However, electron beams typically couple only weakly to optical excitations, and emerging applications in electron control and sensing.sup.8-11 require large enhancements using tailored fields and interactions. Here we couple a free-electron beam to a travelling-wave resonant cavity mode. The enhanced interaction with the optical whispering-gallery modes of dielectric microresonators induces a strong phase modulation on co-propagating electrons, which leads to a spectral broadening of 700 electronvolts, corresponding to the absorption and emission of hundreds of photons. By mapping the near-field interaction with ultrashort electron pulses in space and time, we trace the lifetime of the the microresonator following a femtosecond excitation and observe the spectral response of the cavity. The natural matching of free electrons to these quintessential optical modes could enable the application of integrated photonics technology in electron microscopy, with broad implications for attosecond structuring, probing quantum emitters and possible electron-light entanglement. The coupling between light and relativistic free electrons is enhanced through phase matching of electrons with optical whispering-gallery modes in dielectric microspheres and through extended modal lifetimes., Author(s): Ofer Kfir [sup.1] , Hugo Lourenço-Martins [sup.1] , Gero Storeck [sup.1] , Murat Sivis [sup.1] , Tyler R. Harvey [sup.1] , Tobias J. Kippenberg [sup.2] , Armin Feist [sup.1] [...]

Published
2020
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31. Massively parallel coherent laser ranging using a soliton microcomb

Author

Riemensberger, Johann, Lukashchuk, Anton, Karpov, Maxim, Weng, Wenle, Lucas, Erwan, Liu, Junqiu, and Kippenberg, Tobias J.

Subjects
Optical radar -- Equipment and supplies -- Usage -- Research, Optics -- Research, Lasers -- Resonators, Laser communication systems -- Research -- Usage -- Equipment and supplies, Solitons -- Usage -- Equipment and supplies -- Research, Laser and infrared communication, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Coherent ranging, also known as frequency-modulated continuous-wave (FMCW) laser-based light detection and ranging (lidar).sup.1 is used for long-range three-dimensional distance and velocimetry in autonomous driving.sup.2,3. FMCW lidar maps distance to frequency.sup.4,5 using frequency-chirped waveforms and simultaneously measures the Doppler shift of the reflected laser light, similar to sonar or radar.sup.6,7 and coherent detection prevents interference from sunlight and other lidar systems. However, coherent ranging has a lower acquisition speed and requires precisely chirped.sup.8 and highly coherent.sup.5 laser sources, hindering widespread use of the lidar system and impeding parallelization, compared to modern time-of-flight ranging systems that use arrays of individual lasers. Here we demonstrate a massively parallel coherent lidar scheme using an ultra-low-loss photonic chip-based soliton microcomb.sup.9. By fast chirping of the pump laser in the soliton existence range.sup.10 of a microcomb with amplitudes of up to several gigahertz and a sweep rate of up to ten megahertz, a rapid frequency change occurs in the underlying carrier waveform of the soliton pulse stream, but the pulse-to-pulse repetition rate of the soliton pulse stream is retained. As a result, the chirp from a single narrow-linewidth pump laser is transferred to all spectral comb teeth of the soliton at once, thus enabling parallelism in the FMCW lidar. Using this approach we generate 30 distinct channels, demonstrating both parallel distance and velocity measurements at an equivalent rate of three megapixels per second, with the potential to improve sampling rates beyond 150 megapixels per second and to increase the image refresh rate of the FMCW lidar by up to two orders of magnitude without deterioration of eye safety. This approach, when combined with photonic phase arrays.sup.11 based on nanophotonic gratings.sup.12, provides a technological basis for compact, massively parallel and ultrahigh-frame-rate coherent lidar systems. A massively parallel coherent light detection and ranging (lidar) scheme using a soliton microcomb--a light source that emits a wide spectrum of sharp lines with equally spaced frequencies--is described., Author(s): Johann Riemensberger [sup.1] , Anton Lukashchuk [sup.1] , Maxim Karpov [sup.1] , Wenle Weng [sup.1] , Erwan Lucas [sup.1] , Junqiu Liu [sup.1] , Tobias J. Kippenberg [sup.1] Author [...]

Published
2020
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34. Integrated turnkey soliton microcombs

Author

Shen, Boqiang, Chang, Lin, Liu, Junqiu, Wang, Heming, Yang, Qi-Fan, Xiang, Chao, Wang, Rui Ning, He, Jijun, Liu, Tianyi, Xie, Weiqiang, Guo, Joel, Kinghorn, David, Wu, Lue, Ji, Qing-Xin, Kippenberg, Tobias J., Vahala, Kerry, and Bowers, John E.

Published
2020
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44. A microphotonic astrocomb

Author

Obrzud, Ewelina, Rainer, Monica, Harutyunyan, Avet, Anderson, Miles H., Liu, Junqiu, Geiselmann, Michael, Chazelas, Bruno, Kundermann, Stefan, Lecomte, Steve, Cecconi, Massimo, Ghedina, Adriano, Molinari, Emilio, Pepe, Francesco, Wildi, François, Bouchy, François, Kippenberg, Tobias J., and Herr, Tobias

Published
2019
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