Optics express最新文献

We demonstrate experimentally the generation of 1064 nm watt-level optical skyrmions and bimerons with first order Néel, Bloch, and anti polarization textures based on a continuous-wave Nd:YVO₄ laser with a dual output coupler cavity configuration. The estimated skyrmion number of these quasiparticles is > 0.94.

Integrating functionalized quantum dot (QD) components on integrated photonic circuits is an enabling technology to realize unprecedented optical functionalities beyond the capacities of passive photonic devices. Here, we demonstrate a fast-response infrared lead sulfide (PbS) QD photodetector operating at 1550 nm wavelength. Fabricated by a low-cost layer-by-layer process on a 2 cm × 2 cm glass substrate, this device is compatible with wafer-scale large-volume manufacturing. We systematically characterize the absorption properties of the QD solution, QD film, and the final fabricated photodetectors. Our photodetector exhibits a responsivity of 2.61 × 10^-3 A/W at zero bias, which is further boosted to 0.16 A/W at -1 V bias, with photoresponse spanning the telecom S- and C-bands. The photodetector features a -3 dB bandwidth of 4 kHz and a rapid rise time of 86.7 µs. For the first time, we showcase the photodetector in acetylene gas absorption spectroscopy and high-Q tantalum pentoxide microresonator transmission spectrum characterizations, and achieve excellent agreement with the results measured by commercial detectors. This work presents a critical step towards fully integrated QD-incorporated optoelectronic circuits, paving the way to complicated integrated photonic systems that could be deployed for on-chip sensing, optical communication, and optical computing.

After transmitting through a disordered medium, a squeezed state would conceivably exhibit excess noise above the shot-noise level. Recent advancements have demonstrated that the technique of single-sided wavefront shaping provides an effective avenue to suppress the excess noise. Nevertheless, the minimum suppressed noise remains above the initial squeezed noise level. Inspired by full-reflection structures enabling novel optical phenomena, we propose an alternative noise-reduction scheme combining a zero-transmission structure with wavefront shaping, which further reduces the excess quantum fluctuations. Intriguingly, when the input is a single-mode squeezed state, the excess fluctuation can be fully erased. Therefore, our approach paves another way for the elimination of the excess noise induced by multiple scattering in disordered media.

We present the design and characterization of a guided-wave, bright, and highly frequency non-degenerate parametric down-conversion (PDC) source in thin-film lithium niobate. The source generates photon pairs with wavelengths of 815 nm and 1550 nm, linking the visible wavelength regime with telecommunication wavelengths. We confirm the high quality of the generated single photons by determining a value for the heralded second-order correlation function as low as gh(2)(0)=(6.7±1.1)⋅10^-3. Furthermore, we achieve a high spectral brightness of 0.44·10⁷pairss⋅mW⋅GHz which is two orders of magnitude higher than sources based on weakly guiding waveguides. The shape of the PDC spectrum and the strong agreement between the effective and nominal bandwidth highlight our high fabrication quality of periodically poled waveguides. The good agreement between the measured and simulated spectral characteristics of our source demonstrates our excellent understanding of the PDC process. Our result is a valuable step towards practical and scalable quantum communication networks as well as photonic quantum computing.

Many optical techniques exploit interference in deterministic turbid media such as colloids and biological tissues. For instance, wavefront shaping methods that focus light in such materials do so by optimizing self-interference patterns. Despite significant interest, simulating such processes can be challenging. One issue is representing the known properties of the medium. Often, only mesoscale parameters such as the scattering coefficient are known. While these can be replicated-for example, using sphere suspensions designed via Mie theory-such representations are not directly compatible with simulation methods that require spatially sampled refractive index distributions. Another issue is computational complexity. Full-wave simulations traversing the length scales of practical experiments, e.g., thick biological tissue sections, are often beyond the limits of existing tools. To address this challenge, we developed a simulation method coupling together a sphere-based representation of the turbid media with a T-matrix method of computing the light fields. As T-matrix calculations can work directly on Mie-theory designed sphere suspensions, this provides a physically consistent and computationally efficient way to model coherent light transport in turbid media. To demonstrate the approach, we simulated light propagation and focusing in and around a diffusive layer and an 800 µm thick biological tissue section. By enabling deterministic coherent optics simulations in the ballistic, quasi-ballistic and diffusive regimes, the work provides a tool that could aid the development of a range of techniques exploiting coherent phenomena in turbid media.

The hydrophobicity of a material surface is crucial for its self-cleaning, antifouling, and anticorrosion properties. In this paper, an approach for enhancing surface hydrophobicity is presented, in which laser speckle grayscale lithography combined with soft embossing is employed to fabricate microstructures on polydimethylsiloxane (PDMS). By adjusting the exposure dose and laser speckle size, the surface morphology and, consequently, the wettability of the PDMS showed regular changes. Without any post-treatment, the patterned PDMS exhibited a higher water contact angle (144.2°) than the intrinsic contact angle of PDMS (100.6°). This approach offers a simple and cost-effective route for enhancing the hydrophobicity of surfaces.

Dynamic scattering media video reconstruction represents one of the most challenging problems in computational imaging, with applications ranging from autonomous driving under adverse weather conditions to biomedical imaging through turbid tissues. Traditional approaches are often limited in their ability to capture the complex temporal dynamics and physics-based constraints inherent in scattering phenomena, which can result in reduced reconstruction quality and restricted applicability. In this work, we present PISTA (Physics-Informed Spatio-Temporal Transformer Architecture), a deep learning framework that integrates physical principles with advanced attention mechanisms for improved video reconstruction through dynamic scattering media. Our approach addresses three fundamental limitations of existing methods: incomplete modeling of temporal correlations in scattering dynamics, insufficient incorporation of physics-based constraints into neural network architectures, and limited parameter estimation for time-varying scattering properties. PISTA employs a physics-informed encoder that enforces energy conservation, temporal causality, and reciprocity, coupled with a spatio-temporal attention module that captures long-range dependencies across both spatial and temporal dimensions. Furthermore, we introduce a parameter estimation network that adaptively learns scattering coefficients, enabling reconstruction that is responsive to dynamic medium variations. We validate the proposed framework on both physics-based synthetic data and the OTIS real turbulence dataset, demonstrating notable improvements over conventional CNN- and transformer-based baselines. Overall, PISTA provides a physically consistent and data-efficient solution for video reconstruction in dynamic scattering environments.

High harmonic spectroscopy is a powerful tool that provides insights into molecular structure and multielectron dynamics with attosecond-ångström resolution. The spectral features of high harmonic emissions encode vital information about the underlying molecular structure and dynamics, influenced primarily by two interference effects: structural two-center interference and multichannel dynamic interference. These interferences manifest as intensity minima in the harmonic spectra. Additionally, the spectral phase, critical for wavefunction reconstruction and understanding molecular dynamics, displays distinct behaviors linked to these interferences. In this work, we conduct a comprehensive analysis of the contrasting phase jumps associated with these interference mechanisms within the framework of the strong-field approximation (SFA). Our findings reveal the physical origins of the observed spectral phase variations and underscore the potential of spectral phase information in probing molecular dynamics at ultrafast timescales.

Quantum key distribution (QKD) leverages the principles of quantum mechanics to provide theoretically unconditional security for cryptographic key sharing. However, practical implementations remain vulnerable due to potential security loopholes at both the source and detection sides of QKD systems. The side-channel-secure (SCS) protocol addresses these challenges by encoding bits in vacuum and non-vacuum states and introducing a third-party measurement node, thereby repelling attacks targeting the detection side as well as external lab attacks on the source side. In this work, we consider the state-dependent correlated errors and Trojan-horse attack while preserving the SCS protocol's key advantage--specifically, requiring only upper bounds on intensity characterization without needing a full description of quantum states in infinite dimensions. Numerical results demonstrate that when the reflected light intensity from Trojan-horse attacks falls below 10^-6, Eve can scarcely extract additional key information from the reflections. This work makes the SCS protocol more practical.

As a form of interferometric imaging, synthetic aperture optical imaging systems assume a pivotal role in the realm of optical imaging. The optical path difference (OPD) exerts a profound influence on the quality of interferometric imaging outcomes. Nevertheless, existing approaches for optical path correction predominantly rely on mechanical structures for compensation purposes. This paper presents a passive laser heterodyne measurement approach that utilizes a laser as the local oscillator (LO) signal. We have verified that upon the superposition of independent lasers and incoherent broadband light, beat frequency components emerge within the frequency domain. Leveraging the passive heterodyne theory, these components can be efficiently extracted and analyzed. By deploying two passive heterodyne units to detect the identical light source, the optical path difference between the two signals can be ascertained via the cross-correlation function of the two beat frequency signals. Furthermore, digital compensation techniques can be utilized to accomplish precise phase matching between the two light beams. This method surmounts the limitations of conventional dual-beam superposition techniques and puts forward a potential digital correction strategy for the optical path correction of synthetic apertures.