Optics
Few-cycle electro-optic light on thin-film lithium niobate
Xinyi Ren, Chun-Ho Lee, Ian Christen et al. (+6 more)
The twin fields of ultrafast optics and nonlinear photonics enable applications ranging from attosecond science [1, 2] and ultrafast electronics [3] to molecular spectroscopy [4, 5], nonlinear optics [6-8],
quantum nanophotonics [9] and precision metrology [10]. However, bringing these capabilities-including ultrashort pulse generation, dispersion control, and strong nonlinear interactions-together within a scalable photonic integrated platform requires exceptional performance and cooperation between components while preserving sufficient optical power across the
circuit. Here we demonstrate an integrated multi-functional nonlinear photonic system that transforms continuous-wave (CW) light into high-peak-power femtosecond pulses and harnesses them for pulse-driven nonlinear optics on thin-film lithium niobate (TFLN). Microwave-driven electro-optic (EO) broadening followed by integrated dispersive compression generates 230-fs
Fourier-transform-limited pulses with energies up to 3.3 pJ at 30.7 GHz, representing orders of magnitude higher pulse energy than previous integrated pulse synthesis at comparable repetition rates [11]. In a 0.3-meter dispersion-engineered TFLN waveguide,
soliton dynamics compress the pulses to 35 fs (6.7 optical cycles), accompanied by coherent spectral broadening exceeding 330 nm. In a fully-monolithic architecture, EO synthesis, dispersive compression and a high-Q nonlinear resonator are integrated on a single TFLN chip, enabling resonantly-enhanced pulse pumping and coherent spectral broadening at pulse energies as low as 400 fJ. By unifying microwave-controlled pulse synthesis and pulse-driven nonlinear interactions, our work establishes a direct path from CW excitation to few-cycle nonlinear optics on chip, with opportunities spanning microwave photonics [12], optical frequency synthesis and metrology, and mid-infrared and terahertz generation [13, 14].
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All authors Xinyi Ren, Chun-Ho Lee, Ian Christen, Clayton Cheung, Reshma Kopparapu, Yue Yu, Lian Zhou, Zaijun Chen, Mengjie Yu
Optics · Cross-listed from cond-mat.str-el
Floquet Green's functions for lattice electrons driven by Gaussian quantum light
Atsushi Ono
We formulate Floquet Green's functions for noninteracting single-band
lattice electrons driven by a reservoir-stabilized single-mode Gaussian
quantum light source. The source is prescribed externally and is not updated by the many-electron polarization, while an active electronic probe still conditions the source
evolution through the Peierls coupling. The two time arguments of a Green's function share one source history: the lesser and greater components are obtained by convolving a shared-history four-endpoint kernel with the continuous bath kernels before the final source trace, while the bath canonical anticommutation relation yields an equal-time covariance that seeds the retarded and advanced one-leg propagations. The Peierls coupling is treated nonperturbatively within the prescribed-source model, and classical Floquet theory is recovered in the appropriate limit. Numerical calculations on a minimal one-dimensional model show finite-coupling
quantum-source corrections beyond a prescribed classical drive, together with spectral reconstruction and occupancy redistribution for squeezed
vacuum and squeezed coherent sources. The squeezing parameter and phase provide additional control knobs, beyond classical amplitude modulation, for both sideband structure and occupied weight. This work provides a theoretical framework for
quantum Floquet engineering of condensed matter with an externally prescribed
quantum light source.
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Optics · Cross-listed from quant-ph
Impact of strain and dark states on spectroscopic measurements of silicon-vacancy centers in diamond
Tommy Chin, Kesav V. Narayan, Imran Bashir et al. (+4 more)
Negatively charged silicon-vacancy (SiV$^-$) centers in diamond offer an attractive platform for the development of many forms of
quantum technology. However, questions remain in connection to how large ensembles of SiV$^-$ centers behave in concert. Here, we develop a computational model designed to simulate recent experiments where optical multidimensional coherent spectroscopy (MDCS) was used to examine a high-concentration sample of SiV$^-$ centers in diamond, revealing significant variations in spectral signature depending on the detection scheme. Simulation results reveal that strain effects are highly random in this system, with a characteristic axial strain of $2.8 \times 10^{-4}$ and a shear strain of $3.5 \times 10^{-5}$. They suggest in addition that highly strained centers (with values exceeding $1.5 \times 10^{-5}$) may become significantly decoupled from optical emission. The results have implications for the use of SiV$^-$ centers as
quantum sensors.
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All authors Tommy Chin, Kesav V. Narayan, Imran Bashir, Kelsey M. Bates, Liam G. Stanton, Ehsan Khatami, Christopher L. Smallwood
Optics
High-dimensional Supermode Photonics Enabled by Hierarchical Supersymmetric Transformation
Yuan Zhong, Kaile Chen, Qi Lu et al. (+8 more)
Modes provide a fundamental degree of freedom for photonic information processing, yet conventional multimode waveguides exhibit non-equidistant effective-index distributions, making closely spaced modes vulnerable to intermodal crosstalk. Supermode photonics can overcome this limitation by geometrically engineering coupled waveguide arrays to realize large and equidistant effective-index spacing, but precise supermode excitation and detection remain challenging at the subwavelength scale. Here, we report a hierarchical second-order discrete supersymmetric (DSUSY) transformation method that enables high-purity excitation and extraction of arbitrary target supermodes in a compact and scalable architecture. We experimentally demonstrate six-supermode multiplexing systems on silicon-on-
insulator and silicon nitride platforms. Benefiting from the large supermode index spacing and the isospectrality of DSUSY transformations, the fabricated devices exhibit low insertion losses (<2.6 dB) and intermodal crosstalk (<-11.1 dB) for all channels over a 100-nm wavelength range. A high-speed transmission experiment on the silicon device achieves an aggregate data rate of 1.2 Tbit/s, with all channel bit error rates below the 7% hard-decision forward-error-correction threshold. The method can further support polarization-insensitive architectures, enabling compact polarization-supermode hybrid multiplexing. This work provides a scalable route toward high-dimensional supermode photonics for high-capacity optical interconnects, highly parallel AI optical computing, and high-dimensional
quantum information processing.
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All authors Yuan Zhong, Kaile Chen, Qi Lu, Chunxue Wang, Jingchi Li, Yuru Li, Zhaohui Li, Chao Lu, Xinchen Ji, Yikai Su, Lu Sun
Optics
Non-resonant laser-driven narrowing of particle velocity distributions
Ashwini Vaishnav, Matthias Rupp, Olivier De Castro et al. (+2 more)
Stark acceleration and deceleration based techniques for generating particle ensembles with low velocity spread are useful in many experimental applications. For a given velocity distribution of a particle ensemble, these techniques accelerate or decelerate a small subset of the total population, with a low velocity uncertainty. However, narrowing the original velocity distribution by accelerating or decelerating the ensemble particles near the mean velocity is fundamentally limited and not yet explored. We present a numerical study of particle dynamics using neutral cesium atoms as an example. We investigate different interaction regimes, identify key limitations, and propose an interaction regime in which optical Stark deceleration can be used to narrow the velocity distribution of a propagating ensemble about its mean velocity. These findings have potential implications for optical manipulation and control, controlled collisions, and matter interferometry.
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All authors Ashwini Vaishnav, Matthias Rupp, Olivier De Castro, Mikhail N. Shneider, Alexandros Gerakis
Optics
Plasmonic Fourier Surfaces Revisited: Relating Bandgaps with Bound States in the Continuum
Alexander A. Antonov, Connor Heimig, Hannah Niese et al. (+5 more)
Periodically corrugated metal interfaces supporting surface plasmon polaritons (SPPs) belong to the earliest nanoplasmonic platforms. Even simplest reliefs described by a few harmonics - plasmonic
Fourier surfaces - display markedly different far-field signatures depending on the corrugation depth and
symmetry: shallow reliefs exhibit a plasmonic bandgap (PBG) between two hybridized SPP standing waves, while deeper reliefs support asymmetry-induced single sharp resonances, termed over the last decade as quasi-bound states in the continuum (qBICs). Although these spectral features have long been observed experimentally and treated empirically, the underlying eigenmode
evolution connecting the shallow and deep corrugation regimes has remained largely unexplored. Here we revisit this long-standing problem by analyzing it in terms of modern eigenstate formalism. Starting from the Rayleigh hypothesis, we develop a concise first-principle analytical description that explicitly captures how one eigenmode transforms from a dark bound state into an observable qBIC, while the other turns from bright into an overcoupled, unobservable state - thus unifying the SPP manifestations featuring PBG and qBIC within the same eigenmode framework. Finally, we demonstrate the practical relevance of the theory by showing how precise eigenstate engineering can enhance the SPP refractive index sensitivity.
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All authors Alexander A. Antonov, Connor Heimig, Hannah Niese, Yannik M. Glauser, Sander J. W. Vonk, David J. Norris, Maxim V. Gorkunov, Andreas Tittl
Optics · Cross-listed from quant-ph
Boosting self hybridized exciton polaritons with metal clad WS2 waveguides
Filip Majstorovic, Masoud Taleb, Victor DeManuel-Gonzalez et al. (+2 more)
The formation of Fabry Perot and guided wave self hybridized
exciton polaritons in two dimensional materials results in long range
exciton energy transfer and strong
exciton exciton interactions. Here, we demonstrate that the coupling strength between photonic modes and
excitons is significantly boosted by
embedding the active excitonic layer in a metal clad WS2 waveguide. The photonic modes in this waveguide exhibit modified dispersion properties for both Fabry Perot type and guided wave
exciton polaritons compared to pure WS2 flakes, and show an increased couplingr strength. Our results provide a robust approach for controlling
exciton photon interactions and their coupling strength in hybrid
heterostructures.
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All authors Filip Majstorovic, Masoud Taleb, Victor DeManuel-Gonzalez, Kai Rossnagel, Nahid Talebi
Optics
Optical-Memory Transport Imaging: A Transport-History Framework for Finite-Memory Tracers
Haichun Liu and Jerker Widengren
Finite-
memory optical tracers encode upstream transport histories rather than instantaneous local flow velocities. We introduce optical-
memory transport (OMT) imaging, a framework in which finite
memory couples internal-state relaxation to transport through
memory kernels. Under structured illumination, these histories are converted into measurable complex spatial-frequency response, whose local transfer-function limit yields constant-velocity inversion. Fisher-information analysis establishes kernel-dependent information limits and design principles for finite-
memory transport imaging.
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Optics
Rf beam steering using on-ohip optical true time delay on 3 micrometer siliocn on insulator platfrom
Somnath Paul, Jussi Saily, Markus Schroder et al. (+2 more)
We present the design, packaging, and system-level experimental demonstration of a reconfigurable 5-bit, 4-channel optical true time delay (OTTD) chip realized on a 3 micrometer thick silicon on
insulator (SOI) platform at VTT. The chip enables 32 discrete delay states over a 0 to 101 picoseconds range, with a delay resolution of 3.25 picoseconds, making it well suited for broadband RF beamforming with upcoming 6G FR3 band systems around 10 GHz. Each channel incorporates five binary weighted delay stages controlled by Mach-Zehnder interferometer (MZI) based thermo-optic switches with an extinction ratio exceeding 25 decibels and an average switching power of 25 milliwatts. The chip is embedded within an analog
radio-over-fibre (A-RoF) link, and the outputs are connected to a PCB-based four-element patch
antenna array. Accurate RF beam steering is demonstrated at broadside and at 30 degrees from broadside using a 16 - QAM signal modulated at 100 MBaud on a 10 GHz carrier. An error vector magnitude (EVM) degradation of approximately 1 percent is observed upon steering, and an extinction ratio exceeding 50 decibels is measured between the two receiver positions. The results confirm the potential of integrated OTTD technology for compact, power-efficient, and broadband beamforming in next-generation wireless and radar systems.
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All authors Somnath Paul, Jussi Saily, Markus Schroder, Mikko Harjanne, Timo Aalto
Optics
Quantum Theory of Third-harmonic Generation in Epsilon-Near-Zero Materials
Sonia Alipour, Riccardo Franchi, Tornike Shubitidze et al. (+3 more)
We present a theoretical framework, based on the Green's tensor quantization method, to describe third-harmonic generation in epsilon-near-zero (ENZ) materials and derive analytical, closed-form solutions for the generation efficiency. We validate our model against experimental measurements of wavelength- and angle-resolved third-harmonic generation efficiency from 30 nm-thin ITO nanolayers at low pump intensity, described under the undepleted pump approximation. Our results provide a local and scalar effective model for
quantum nonlinear processes in dispersive and lossy ENZ media, and establishes a simple and reliable framework for investigating a variety of nonlinear optical phenomena with applications to
quantum sensing,
quantum information, and
quantum nondemolition measurements.
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All authors Sonia Alipour, Riccardo Franchi, Tornike Shubitidze, Smridhi Chawla, Luca Dal Negro, Marco Ornigotti
Optics · Cross-listed from cond-mat.mes-hall
Revealing time characteristics of optical excitations in dielectric and plasmonic structures through cathodoluminescence interferometry
Evelijn Akerboom, Hirohsi Sugimoto, Minoru Fujii et al. (+5 more)
Cathodoluminescence (CL) spectroscopy provides access to optical excitations with nanometer spatial resolution, but direct time-resolved measurements of optical resonances remain challenging. Here, we demonstrate that CL interferometry provides access to the temporal response, phase behavior, and modal spectral structure of resonant nanoscale scatterers without requiring ultrafast pump-probe schemes. We develop an analytical framework in which
Fourier transformation angle- and frequency-resolved CL interferograms yields the decay time of optical resonances governed by the linear optical response. Multimode resonators exhibit characteristic temporal CL beating signatures associated with spectral mode splitting. By exploiting transition radiation emitted from a nearby metallic surface as a broadband reference, we further demonstrate phase
retrieval and cross-correlation measurements between instantaneous and resonant emission processes. Experimental measurements on Au nanoparticles, broadband plasmonic emitters, Au nanostars, and Si nanospheres supporting multipolar Mie resonances confirm the theoretical predictions, and decay times in the range 1-10 fs are derived for each system. Our results establish CL interferometry as a powerful approach for accessing spectral, spatial, and phase information within a single nanoscale measurement with fs resolution.
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All authors Evelijn Akerboom, Hirohsi Sugimoto, Minoru Fujii, Nicolas Pazos-Perez, Ramon A. Álvarez Puebla, A. Femius Koenderink, F. Javier García de Abajo, Albert Polman
Optics
Stability of Orbital Angular Momentum Modes in Conventional and Ring-Core Optical Fibers
Hassan Asgharzadeh B., Regina Gumenyuk and Marco Ornigotti
Modal dynamics in multimode optical fibers are fundamentally governed by the inter- play between phase matching and intermodal coupling. In this work, we investigate the fundamental coupling mechanisms in ring-core fibers and identify a geometry-induced cou- pling suppression that significantly reduces coupling coefficients between orbital angular momentum modes compared to conventional multimode step-index fibers. This mechanism provides a clear physical explanation for the superior transmission stability of orbital angular momentum modes in ring-core fibers and establishes specific
geometric constraints for the design of ring-core fiber-based mode converters.
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Optics
Strong, Mode-Selective Evxciton-Photon Coupling Driven by Polariton Scattering in the Mo2 Complexes at Ambient Conditions
Miao Meng, Ying Ning Tan, Zi Cong He et al. (+2 more)
Quadruply bonded Mo2 complexes provide a distinctive molecular platform in which multiple two-level electronic transitions interact with quantized scattering modes under ambient conditions. Here we show that, in the Mo2 complexes, the intrinsic photonic modes selectively couple to molecular excitations, including the characteristic delta-delta(
star), ligand to metal charge transfer (LMCT) and metal to ligand charge transfer (MLCT) transitions, to form the well-resolved
exciton-
photon hybrid states. By combining steady-state absorption, resonance fluorescence, and ultrafast transient spectroscopies, we identify distinct polaritonic branches associated with these electronic
manifolds, with coupling strengths spanning the strong and ultrastrong regimes (g/omega0 up to 0.1). Mode-selective coupling accounts for the pronounced spectral reorganization for the singly oxidized complexes, including the emergence of absorption valleys and sidebands of the associated resonances in the steady-state spectra, characteristic polaritonic emissions in the photoluminescence spectra, and long-lived low-energy hybrid states in the transient spectra. These results support the picture that the Mo2 unit functions as an integrated molecular resonator whose intrinsic quantized field selectively drives and redistributes molecular excitations. This work strengthens the emerging view of bonded dimetal complexes as ambient-condition molecular
quantum systems and provides a chemically defined platform for exploring polaritonic chemistry.
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All authors Miao Meng, Ying Ning Tan, Zi Cong He, Yuli Zhou, Chun Y. Liu
Optics · Cross-listed from quant-ph
Nanoscale graphitization and defect evolution in silicon-vacancy center-containing nanodiamonds under high-pressure high-temperature annealing
M. De Feudis, B. Yavkin, L. Henry et al. (+6 more)
Group-IV color centers, such as the silicon-vacancy (SiV) defect, are highly promising for solid-state
quantum technologies. However, nanodiamonds typically exhibit significant
lattice strain and structural disorder, which degrade their optical properties and hinder the resolution of the fine spectral structure at cryogenic temperatures. High-pressure high-temperature (HPHT) annealing offers a potential route to relax internal strain, although the phase stability of diamond at the nanoscale under such conditions remains poorly constrained. Here, we investigate the structural
evolution of nanodiamonds during HPHT annealing using a Paris-Edinburgh press coupled with in situ synchrotron X-ray diffraction at SOLEIL. A dedicated sample assembly combining nanodiamonds - NaCl - Pt enabled accurate pressure-temperature calibration and real-time monitoring of phase transformations. The diffraction data reveal that the onset of diamond-to-graphite transition occurs at approximately 1800 K at 2 GPa and 2120 K at 4 GPa under the applied HPHT heating protocol. These experimentally determined graphitization onsets define a practical pressure-temperature processing window for HPHT annealing of nanodiamonds while avoiding detectable graphitization and provide a calibrated framework for reliable off-beam annealing treatments that avoid graphitization. Photoluminescence measurements on samples annealed below the graphitization threshold show improved optical response, with partial resolution of the SiV fine structure at 12 K. These optical measurements suggest a relationship between nanoscale phase stability and the optical response of individual SiV-containing nanodiamonds following HPHT annealing. The experimentally established HPHT processing window provides a practical framework for the controlled processing of
quantum nanodiamonds while avoiding graphitization.
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All authors M. De Feudis, B. Yavkin, L. Henry, K.O. Ho, M.-P. Adam, P. Goldner, F. Benedic, S. Desgreniers, J.-F. Roch
Optics
Direct experimental measurement of femtonewton-scale momentum transfer force from electron beams
Chunbo Lin, Xinggang Shang, Xijun Li et al. (+6 more)
Electron beams (e-beams) are ubiquitous in imaging, patterning, and propulsion. This prevalence is rooted in the profound mastery of their wave-particle duality and energy-transfer pathways. Yet, a fundamental dimension remains largely unexplored: while the mechanical effect (i.e., the momentum transfer to a target) is theoretically known, quantification of its femtonewton-range force has remained elusive. This discrepancy represents a missing piece of the puzzle toward a comprehensive understanding of e-beam-matter interactions, and ultimately limits the multi-dimensional exploitation of e-beams. A force sensor combining femtonewton sensitivity, immunity to electromagnetic noise, compatibility with
vacuum, and absolute calibration is critical to bridge the gap between theory and experiment. Here the FINEST (Femtonewton Interferometric Nanomechanical Electron-beam Sensing Technology) sensor is proposed and successfully tested to measure the force of an e-beam. FINEST is an optical-pressure-calibrated 3D spring-type optical sensor that operates reliably under e-beam conditions. Femtonewton-scale forces from 2-30 keV e-beams are directly measured, ranging from 505 fN to 13 pN. Both linear scaling with beam current and a non-monotonic energy dependence (peaking near 10 keV) are observed. Based on this calibrated force, the mechanical contribution to e-beam ice etching was quantitatively confirmed; its effect is orders of magnitude lower than the total etch depth and lacks noticeable energy dependence. By achieving the first direct experimental measurement of e-beam momentum transfer, this work adds a long-missing dimension to the physical landscape of e-beam processes. These findings provide a quantitative basis for furthering the multi-dimensional exploitation of e-beams, potentially transforming our approach to precision nanofabrication, sensing, and fundamental electron physics research.
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All authors Chunbo Lin, Xinggang Shang, Xijun Li, Xiaoyu Sun, Kang Zhao, Xujie Wang, Yang Yu, Wenjing Cao, Min Qiu
Optics
Dispersion Control of Chiral Exciton-Polariton Transport with Dielectric Metasurfaces
Juhyeong Jeon, Kehan Wang, Yu-Chen Wei et al. (+6 more)
Exciton-polaritons provide a powerful platform for manipulating hybrid light-matter states with low effective masses and strong nonlinearities. Introducing chirality into these quasiparticles enables selective control over their
spin and propagation, opening new opportunities for chiral transport and
spin-selective polaritonic devices. We exploit the strong chiral light-matter coupling in silicon metasurfaces composed of tilted nanorod dimers to demonstrate selective transport of organic chiral
exciton-polaritons. The metasurface supports surface
lattice resonances and quasi-bound states in the continuum that simultaneously provide high photonic confinement and extrinsic chirality, giving rise to chiral
exciton-polaritons in the achiral molecules. These
exciton-polaritons exhibit a large magnitude of the dissymmetry factor, reaching a value of 0.93. Using photoluminescence
Fourier microscopy and real-space imaging, we show that chiral
exciton-polaritons propagate over distances exceeding 50 um without significant degradation of their dissymmetry, with characteristic propagation lengths of approximately 6-13 um. These propagation lengths correspond to an enhancement of 3 orders of magnitude compared to bare
excitons. This work constitutes the first demonstration of enhanced and selective chiral transport of organic
exciton-polaritons, driven by strong light-matter coupling, in achiral metasurfaces, paving the way for
spin-selective polaritonic technologies using simple metasurfaces.
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All authors Juhyeong Jeon, Kehan Wang, Yu-Chen Wei, Francesca Cussiol, Matthijs Berghuis, Fan Xu, Shunsuke Murai, E. W. Meijer, Jaime Gómez Rivas
Optics · Cross-listed from cs.NI
Link-adaptive digital twin for robust physical-layer modeling in hybrid-amplified ultra-wideband optical networks
Xiaoxuan Gao, Rentao Gu, Yingchun Wang et al. (+3 more)
Accurate physical-layer modeling is increasingly essential for reliable ultra-wideband operation and capacity optimization, especially under the intensified inter-channel stimulated Raman scattering (ISRS) effect. This paper proposes the link-adaptive digital twin (LA-DT) for hybrid-amplified ultra-wideband links to overcome the generalization and speed limitations of existing methods, achieving accurate modeling and robust generalized signal-to-noise ratio (GSNR) estimation across diverse links. First, to address EDFA heterogeneity, the GSNR modeling task is decomposed into three key power predictions: ASE, NLI, and signal powers before EDFA entry. Second, to enhance cross-scenario generalization, three dedicated DT models are developed using a novel neural architecture with linear modulation layers (LMLs). Third, for rapid adaptation to unseen scenarios with limited data, three domain discriminators guide few-shot fine-tuning of the LMLs. Fourth, the LA-DT explicitly accounts for Raman amplifier (RA) insertion loss, improving practical deployment reliability. Results across 35 scenarios show that LA-DT reduces RMSE for NLI, ASE, and signal power predictions to 0.151, 0.111, and 0.113 dBm with improvements of 56.0%, 58.4%, and 52.7% over the baseline,and achieves an average GSNR estimation RMSE of 0.114 dBm (55.8% improvement). For 12 unseen scenarios, the LA-DT maintains high accuracy through few-shot fine-tuning with only 20 samples per scenario, achieving an average GSNR RMSE of 0.159 dB and demonstrating strong adaptability and robustness.
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All authors Xiaoxuan Gao, Rentao Gu, Yingchun Wang, Xinyi Liu, Junshi Gao, Yuefeng Ji
Optics
730-nm optical parametric conversion from near- to short-wave infrared band
J. M. Chavez Boggio, J. R. Windmiller, M. Knutzen et al. (+6 more)
A record 730 nm parametric conversion in silica fiber from the near-infrared to the short-wave infrared band is reported and analyzed. A parametric gain in excess of 30 dB was measured for a signal at 1300 nm (with corresponding idler at 2030 nm). This conversion was performed in a travelling single-pass one-pump parametric architecture and high efficiency is achieved by a combination of high peak power and a nonlinear fiber with a reduced fourth-order dispersion coefficient.
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All authors J. M. Chavez Boggio, J. R. Windmiller, M. Knutzen, R. Jiang, C. Bres, N. Alic, B. Stossel, K. Rottwitt, S. Radic
Optics
Toward a Thermodynamic Framework for Dissipative Solitons: From Photonics to Turbulence and Bose–Einstein Condensate Analogies
Vladimir L. Kalashnikov and Irina T. Sorokina
# Abstract Thermodynamic concepts are increasingly used in nonlinear photonics to describe Rayleigh–Jeans thermalization, optical wave
turbulence, condensation, negative-temperature states, and statistical mode locking. This raises a broader question: how far can thermodynamic
reasoning be extended to localized structures maintained far from
equilibrium by a balance of gain, loss, dispersion, and nonlinearity? We address this question using strongly chirped dissipative
solitons (DSs) of the complex cubic–quintic Ginzburg–Landau equation (CQGLE) as a model system. Their internal energy flows and separation of correlation scales connect coherent solitary waves with semi-incoherent wave kinetics, driven open systems, and Bose–Einstein-condensation analogies. We review thermodynamic-like descriptions based on spectral
entropy, internal energy, effective temperature, and condensation-like spectral restructuring, relating them to dissipative-
soliton resonance (DSR),
stochastic mode-locking self-start, and redistribution between single- and multipulse attractors. Normal and anomalous group-delay dispersion (NGD and AGD) provide complementary realizations: in NGD, DSR is accompanied by spectral localization, scale separation, and increasing accessibility of multipulse states; in AGD, the spectrum has extended wings and dynamical robustness occupies only part of the existence domain. These results distinguish general features of nonequilibrium state selection from effects tied to a particular localization mechanism. We argue that thermodynamic-like observables are best viewed as coarse-grained structural diagnostics rather than
equilibrium state variables, while DSs provide a photonic platform linking nonequilibrium thermodynamics, wave
turbulence, driven condensates, and statistical phase-transition concepts.
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Optics
Causality Sum Rules in Conventional Scattering Matrices
Ning Han, Rui Zhao, Shuxing Yang et al. (+3 more)
Scattering
matrices are the standard experimental and computational description of photonic and electromagnetic devices. Passivity is explicit in the conventional incoming-outgoing
matrix, whereas causality sum rules are usually formulated only after transforming the response into auxiliary variables. Here we show that these rules can be written directly in the conventional scattering
matrix by removing the time advance introduced by the reference domain. Using the earliest-arrival delay of each channel, we define a domain-delayed
matrix that preserves real-frequency passivity while restoring the causal time origin. Under explicit analyticity, transparency, and regularity assumptions, this
matrix becomes a Schur function, enabling a Cayley-Herglotz construction. The resulting projected and determinant bounds constrain coherent channel superpositions and aggregate multichannel loss. The framework recovers Rozanov's absorber limit and spherical-multipole sum rules, while extending causality bounds to measurable quantities including insertion loss, suppressed singular-value channels, and conditional lossless delay-bandwidth trade-offs. Our work directly connects fundamental causality theory with experimentally accessible scattering data. The initial theoretical route is autonomously explored by Qiushi Engine, an AI research system for open-ended scientific discovery, and subsequently verified, refined, and developed by the authors, demonstrating a hybrid AI-human discovery workflow.
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All authors Ning Han, Rui Zhao, Shuxing Yang, Mingzhu Li, Hongsheng Chen, Yihao Yang
Optics · Cross-listed from quant-ph
Private Correlations Certify Sensing Capability
Yunkai Wang, Peixue Wu, Graeme Smith et al. (+1 more)
We show that private correlations in a bipartite
quantum state constitute a metrological resource for distributed sensing assisted by a possibly noisy channel from one party to the other. We begin with an example with distillable secret key but poor locally accessible sensing performance and show that an assisting channel substantially improves its performance. We then show that any shared state yielding positive private information can serve as a sensing resource after appropriate local coherent processing, and derive a quantitative lower bound on the locally accessible sensing capability after assistance. We further show that classical correlations alone provide no analogous guarantee. Finally, in a channel formulation, we show that a channel with positive private information allows nonzero locally accessible sensitivity when paired with a suitable assisting channel.
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All authors Yunkai Wang, Peixue Wu, Graeme Smith, Sisi Zhou
Optics
Outdoor 100-m-scale air waveguides
Andrew Goffin, Gregory Babic, Andrew DeRusha et al. (+3 more)
Optical power densities for standoff spectroscopy, remote sensing, directed energy, and free-space optical communications are limited by diffraction and adverse atmospheric conditions such as
turbulence, fog, and wind. Air waveguides, generated by ultrashort-pulsed
laser filamentation, are a promising approach for transmission and collection of optical signals over long distances, overcoming beam diffraction and, for point-like sources, inverse square signal falloff with distance. In this work, we demonstrate outdoor guiding for the first time over a record length of ~100 m, exceeding the prior (indoor) record of 42 m. We correlate air waveguide performance to a range of real atmospheric conditions including turbulent refractive index structure parameter ($C_n^2$) values up to ~$2.5\times10^{-14} m^{-2/3}$, crosswind speeds up to ~2 m/s, as well as temperature, pressure, and humidity variations. Accompanying propagation simulations provide insight into the real effects of these environmental perturbations, particularly crosswind, on waveguide performance and lifetime. Our results pave the way for quasi-continuous air waveguiding with kHz-scale repetition rate filaments in challenging outdoor environments.
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All authors Andrew Goffin, Gregory Babic, Andrew DeRusha, Maksim Livshits, Howard Milchberg, Patrick Skrodzki