Publications

2024
Joon-Suh Park, Soon Wei Daniel Lim, Arman Amirzhan, Hyukmo Kang, Karlene Karrfalt, Daewook Kim, Joel Leger, Augustine Urbas, Marcus Ossiander, Zhaoyi Li, and Federico Capasso. 1/17/2024. “All-Glass 100 mm Diameter Visible Metalens for Imaging the Cosmos.” ACS Nano, 18, 4, Pp. 3187–3198. Publisher's Version d100mmmetalens_supplementaryinformation.pdf d100mmmetalens_maintext_revised_final.pdf
Dmitry Kazakov, Theodore P. Letsou, Maximilian Beiser, Yiyang Zhi, Nikola Opačak, Marco Piccardo, Benedikt Schwarz, and Federico Capasso. 2024. “Active mid-infrared ring resonators.” Nature Communications, 15, 1, Pp. 607. Publisher's VersionAbstract
High-quality optical ring resonators can confine light in a small volume and store it for millions of roundtrips. They have enabled the dramatic size reduction from laboratory scale to chip level of optical filters, modulators, frequency converters, and frequency comb generators in the visible and the near-infrared. The mid-infrared spectral region (3−12 μm), as important as it is for molecular gas sensing and spectroscopy, lags behind in development of integrated photonic components. Here we demonstrate the integration of mid-infrared ring resonators and directional couplers, incorporating a quantum cascade active region in the waveguide core. It enables electrical control of the resonant frequency, its quality factor, the coupling regime and the coupling coefficient. We show that one device, depending on its operating point, can act as a tunable filter, a nonlinear frequency converter, or a frequency comb generator. These concepts extend to the integration of multiple active resonators and waveguides in arbitrary configurations, thus allowing the implementation of purpose-specific mid-infrared active photonic integrated circuits for spectroscopy, communication, and microwave generation.
active_midir_ring_resonators_maintext.pdf active_midir_ringres_supplementary_information.pdf
Dmitry Kazakov, Nikola Opačak, Florian Pilat, Yongrui Wang, Alexey Belyanin, Benedikt Schwarz, and Federico Capasso. 2024. “Cluster synchronization in a semiconductor laser.” APL Photonics, 9, 2, Pp. 026104. Publisher's VersionAbstract
Cluster synchronization is a general phenomenon in a network of non-locally coupled oscillators. Here, we show that cluster synchronization occurs in semiconductor lasers, where the beat notes between the pairs of adjacent longitudinal modes of the laser cavity constitute a collection of coupled phase oscillators. Non-local coupling arises from the standing-wave nature of the cavity with finite mirror reflectivities, which we can actively control. Varying the coupling, we can bring the laser into a state of cluster synchronization where the two beat note families oscillate at two distinct collective frequencies. Using a coherent beat note detection technique, we show that the beat notes within the two families are synchronized in the opposite configurations—in-phase and antiphase.
kazakov2024_aplphotonics.pdf
Dmitry Kazakov, Theodore P. Letsou, Marco Piccardo, Lorenzo L. Columbo, Massimo Brambilla, Franco Prati, Sandro Dal Cin, Maximilian Beiser, Nikola Opačak, Pawan Ratra, Michael Pushkarsky, David Caffey, Timothy Day, Luigi A. Lugiato, Benedikt Schwarz, and Federico Capasso. 2024. “Driven bright solitons on a mid-infrared laser chip”. Publisher's Version kazakovsoliton2024.pdf
Nikola Opačak, Dmitry Kazakov, Lorenzo L. Columbo, Maximilian Beiser, Theodore P. Letsou, Florian Pilat, Massimo Brambilla, Franco Prati, Marco Piccardo, Federico Capasso, and Benedikt Schwarz. 2024. “Nozaki–Bekki solitons in semiconductor lasers.” Nature, 625, 7996, Pp. 685–690. Publisher's VersionAbstract
Optical frequency-comb sources, which emit perfectly periodic and coherent waveforms of light1, have recently rapidly progressed towards chip-scale integrated solutions. Among them, two classes are particularly significant–-semiconductor Fabry–Perót lasers2–6 and passive ring Kerr microresonators7–9. Here we merge the two technologies in a ring semiconductor laser10,11 and demonstrate a paradigm for the formation of free-running solitons, called Nozaki–Bekki solitons. These dissipative waveforms emerge in a family of travelling localized dark pulses, known within the complex Ginzburg–Landau equation12–14. We show that Nozaki–Bekki solitons are structurally stable in a ring laser and form spontaneously with tuning of the laser bias, eliminating the need for an external optical pump. By combining conclusive experimental findings and a complementary elaborate theoretical model, we reveal the salient characteristics of these solitons and provide guidelines for their generation. Beyond the fundamental soliton circulating inside the ring laser, we demonstrate multisoliton states as well, verifying their localized nature and offering an insight into formation of soliton crystals15. Our results consolidate a monolithic electrically driven platform for direct soliton generation and open the door for a research field at the junction of laser multimode dynamics and Kerr parametric processes.
nozaki_bekki_optical_solitons.pdf
2023
Rui Jie Tang, Soon Wei Daniel Lim, Marcus Ossiander, Xinghui Yin, and Federico Capasso. 11/14/2023. “Time Reversal Differentiation of FDTD for Photonic Inverse Design.” ACS Photonics, 10, 12, Pp. 4140-4150. Publisher's Version ddfdtd_acsphotonics_authors_manuscript.pdf ddfdtd_acsphotonics_supplementary.pdf
Jinsheng Lu, Vincent Ginis, Soon Wei Daniel Lim, and Federico Capasso. 10/6/2023. “Helicity and Polarization Gradient Optical Trapping in Evanescent Fields.” Phys. Rev. Lett., 131, 14, Pp. 143803. Publisher's Version physrevlett.131.143803.pdf
Yun Kai, Jet Lem, Marcus Ossiander, Maryna L. Meretska, Vyacheslav Sokurenko, Steven E. Kooi, Federico Capasso, Keith A. Nelson, and Thomas Pezeril. 9/7/2023. “High-power laser beam shaping using a metasurface for shock excitation and focusing at the microscale.” Opt. Express, 31, 19, Pp. 31308–31315. Publisher's VersionAbstract
Achieving high repeatability and efficiency in laser-induced strong shock wave excitation remains a significant technical challenge, as evidenced by the extensive efforts undertaken at large-scale national laboratories to optimize the compression of light element pellets. In this study, we propose and model a novel optical design for generating strong shocks at a tabletop scale. Our approach leverages the spatial and temporal shaping of multiple laser pulses to form concentric laser rings on condensed matter samples. Each laser ring initiates a two-dimensional focusing shock wave that overlaps and converges with preceding shock waves at a central point within the ring. We present preliminary experimental results for a single ring configuration. To enable high-power laser focusing at the micron scale, we demonstrate experimentally the feasibility of employing dielectric metasurfaces with exceptional damage threshold, experimentally determined to be 1.1 J/cm2, as replacements for conventional optics. These metasurfaces enable the creation of pristine, high-fluence laser rings essential for launching stable shock waves in materials. Herein, we showcase results obtained using a water sample, achieving shock pressures in the gigapascal (GPa) range. Our findings provide a promising pathway towards the application of laser-induced strong shock compression in condensed matter at the microscale.
oe-31-19-31308.pdf
Yijie Shen, Qiwen Zhan, Logan G Wright, Demetrios N Christodoulides, Frank W Wise, Alan E Willner, Kai-heng Zou, Zhe Zhao, Miguel A Porras, Andy Chong, Chenhao Wan, Konstantin Y Bliokh, Chen-Ting Liao, Carlos Hernández-García, Margaret Murnane, Murat Yessenov, Ayman F Abouraddy, Liang Jie Wong, Michael Go, Suraj Kumar, Cheng Guo, Shanhui Fan, Nikitas Papasimakis, Nikolay I Zheludev, Lu Chen, Wenqi Zhu, Amit Agrawal, Mickael Mounaix, Nicolas K Fontaine, Joel Carpenter, Spencer W Jolly, Christophe Dorrer, Benjamín Alonso, Ignacio Lopez-Quintas, Miguel López-Ripa, Íñigo J Sola, Junyi Huang, Hongliang Zhang, Zhichao Ruan, Ahmed H Dorrah, Federico Capasso, and Andrew Forbes. 8/4/2023. “Roadmap on spatiotemporal light fields.” Journal of Optics, 25, 9, Pp. 093001. Publisher's VersionAbstract
Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents a major goal of the everlasting pursue of ultra-fast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell’s equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird’s eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges.
shen_2023_j._opt._25_093001.pdf
Dean Hazineh, Soon Wei Daniel Lim, Qi Guo, Federico Capasso, and Todd Zickler. 7/28/2023. “Polarization Multi-Image Synthesis with Birefringent Metasurfaces.” In 2023 IEEE International Conference on Computational Photography (ICCP), Pp. 1-12. Publisher's Version polarization_multi-image_synthesis_with_birefringent_metasurfaces.pdf
Christina M. Spaegele, Michele Tamagnone, Soon Wei Daniel Lim, Marcus Ossiander, Maryna L. Meretska, and Federico Capasso. 6/16/2023. “Topologically protected optical polarization singularities in four-dimensional space.” Science Advances, 9, 24, Pp. eadh0369. Publisher's VersionAbstract
Optical singularities play a major role in modern optics and are frequently deployed in structured light, super-resolution microscopy, and holography. While phase singularities are uniquely defined as locations of undefined phase, polarization singularities studied thus far are either partial, i.e., bright points of well-defined polarization, or are unstable for small field perturbations. We demonstrate a complete, topologically protected polarization singularity; it is located in the four-dimensional space spanned by the three spatial dimensions and the wavelength and is created in the focus of a cascaded metasurface-lens system. The field Jacobian plays a key role in the design of such higher-dimensional singularities, which can be extended to multidimensional wave phenomena, and pave the way for unconventional applications in topological photonics and precision sensing. Metasurfaces enable topologically protected polarization singularities, paving the way to fault-tolerant precision sensing.
sciadv.adh0369.pdf
Soon Wei Daniel Lim, Joon-Suh Park, Dmitry Kazakov, Christina M Spaegele, Ahmed H Dorrah, Maryna L Meretska, and Federico Capasso. 6/5/2023. “Point singularity array with metasurfaces.” Nature Communications, 14, 3237. s41467-023-39072-6.pdf
Wei Ting Chen, Joon-Suh Park, Justin Marchioni, Sophia Millay, Kerolos MA Yousef, and Federico Capasso. 5/3/2023. “Dispersion-engineered metasurfaces reaching broadband 90% relative diffraction efficiency.” Nature Communications, 14, Pp. 2544. Publisher's Version HighEfficiency_paper.pdf Associated_simulation_files.zip
Jinsheng Lu, Vincent Ginis, Cheng-Wei Qiu, and Federico Capasso. 5/1/2023. “Polarization-Dependent Forces and Torques at Resonance in a Microfiber-Microcavity System.” Phys. Rev. Lett., 130, Pp. 183601. Publisher's Version physrevlett.130.183601.pdf
Ahmed H. Dorrah, Priyanuj Bordoloi, Vinicius S. de Angelis, Jhonas O. de Sarro, Leonardo A. Ambrosio, Michel Zamboni-Rached, and Federico Capasso. 4/10/2023. “Light sheets for continuous-depth holography and three-dimensional volumetric displays.” Nature Photonics. Publisher's Version s41566-023-01188-y.pdf
Marcus Ossiander, Maryna Leonidivna Meretska, Hana Kristin Hampel, Soon Wei Daniel Lim, Nico Knefz, Thomas Jauk, Federico Capasso, and Martin Schultze. 4/6/2023. “Extreme ultraviolet metalens by vacuum guiding.” Science, 380, 6640, Pp. 59-63. Publisher's VersionAbstract
Extreme ultraviolet (EUV) radiation is a key technology for material science, attosecond metrology, and lithography. Here, we experimentally demonstrate metasurfaces as a superior way to focus EUV light. These devices exploit the fact that holes in a silicon membrane have a considerably larger refractive index than the surrounding material and efficiently vacuum-guide light with a wavelength of  50 nanometers. This allows the transmission phase at the nanoscale to be controlled by the hole diameter. We fabricated an EUV metalens with a 10-millimeter focal length that supports numerical apertures of up to 0.05 and used it to focus ultrashort EUV light bursts generated by high-harmonic generation down to a 0.7-micrometer waist. Our approach introduces the vast light-shaping possibilities provided by dielectric metasurfaces to a spectral regime that lacks materials for transmissive optics. The fields of ultrafast spectroscopy and semiconductor photolithography rely on very short wavelengths, typically in the extreme ultraviolet (EUV) realm. However, most optical materials strongly absorb light in this wavelength regime, resulting in a lack of generally available transmissive components. Ossiander et al. designed and fabricated a metalens in which a carefully engineered array of holes in a thin silicon membrane focuses ultrafast EUV pulses close to the diffraction limit by “vacuum guiding.” The results open up transmissive optics to the EUV regime. —ISO Metalens technology can be pushed into the extreme ultraviolet wavelength regime.
EUV_metalens.pdf
Marcus Ossiander, Maryna L. Meretska, Sarah Rourke, Christina Spaegele, Xinghui Yin, Ileana-Cristina Benea-Chelmus, and Federico Capasso. 2/27/2023. “Metasurface-stabilized optical microcavities.” Nature Communications, 14, Pp. 1114. Publisher's Version s41467-023-36873-7.pdf
Lisa W. Li, Noah A. Rubin, Michael Juhl, Joon Suh Park, and Federico Capasso. 2/22/2023. “Evaluation and characterization of imaging polarimetry through metasurface polarization gratings.” Appl. Opt., 62, 7, Pp. 1704–1722. Publisher's VersionAbstract
Metasurfaces are a new class of diffractive optical elements with subwavelength elements whose behavior can be lithographically tailored. By leveraging form birefringence, metasurfaces can serve as multifunctional freespace polarization optics. Metasurface gratings are novel, to the best of our knowledge, polarimetric components that integrate multiple polarization analyzers into a single optical element enabling the realization of compact imaging polarimeters. The promise of metasurfaces as a new polarization building block is contingent on the calibration of metagrating-based optical systems. A prototype metasurface full Stokes imaging polarimeter is compared to a benchtop reference instrument using an established linear Stokes test for 670, 532, and 460&\#x00A0;nm gratings. We propose a complementary full Stokes accuracy test and demonstrate it using the 532&\#x00A0;nm grating. This work presents methods and practical considerations involved in producing accurate polarization data from a metasurface-based Stokes imaging polarimeter and informs their use in polarimetric systems more generally.
ao-62-7-1704.pdf
Vincent Ginis, Ileana-Cristina Benea-Chelmus, Jinsheng Lu, Marco Piccardo, and Federico Capasso. 1/30/2023. “Resonators with tailored optical path by cascaded-mode conversions.” Nature Communications, 14, Pp. 495. Publisher's VersionAbstract

Optical resonators enable the generation, manipulation, and storage of electromagnetic waves. The physics underlying their operation is determined by the interference of electromagnetic waves, giving rise to the resonance spectrum. This mechanism causes the limitations and trade-offs of resonator design, such as the fixed relationship between free spectral range, modal linewidth, and the resonator’s refractive index and size. Here, we introduce a new class of optical resonators, generating resonances by designing the optical path through transverse mode coupling in a cascaded process created by mode-converting mirrors. The generalized round-trip phase condition leads to resonator characteristics that are markedly different from Fabry-Perot resonators and can be tailored over a wide range. We confirm the existence of these modes experimentally in an integrated waveguide cavity with mode converters coupling transverse modes into one supermode. We also demonstrate a transverse mode-independent transmission and show that its engineered spectral properties agree with theoretical predictions.

s41467-023-35956-9.pdf
Giampaolo Pitruzzello. 2023. “Metaoptics for the consumer market (Interview with Prof. Capasso) .” Nature Photonics, 17, Pp. 6-7. Publisher's Version naturephotonics_interview_capasso.pdf

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