Optics express最新文献

During the Warring States period in ancient China, the tiger-shaped tally (TST) was used to securely transmit military commands. It served as the ultimate symbol of the emperor for troop mobilization, and its loss could even mean the total collapse of centralized military control. Inspired by this ancient authentication mechanism, an optical encryption strategy is proposed based on dynamically tunable circular dichroism (CD). The TST are metastructure-photonic crystal composed of periodically alternating layers of tilted potassium bromide and silver. Specifically, the configuration consists of an upper fixed Z-shaped configuration (TST1), a SiO₂ spacer layer, and a lower rotated Z-shaped configuration (TST2). By varying the tilt angle (φ), the azimuthal rotation angle (δ) of TST2, and the incident angle (θ) of the circularly polarized wave, different CD states can be achieved in perfect coordination with TST1. The strategy integrates computational encryption algorithms with physical encryption mechanisms derived from the verification principle of the TST to achieve multi-level information security protection, offering a technical pathway for the development of optical information security technologies.

A 5.58 kW narrow-linewidth linearly polarized single-mode fiber amplifier is demonstrated using a double-parabola active fiber. The fiber design ensures strong fundamental-mode selectivity under bending through its double-parabola refractive index and Yb³⁺-doped profiles, while stress zone modulation is applied to approach the cutoff condition of the fast-axis mode. The system ultimately delivers a 5.58 kW output with a broadened spectrum of 88.5 GHz for SBS suppression, while maintaining a polarization extinction ratio above 19.6 dB throughout the power scaling process and M² ∼ 1.1 at 5.2 kW, representing the highest power-beam quality-polarization combination at this level.

We present what we believe to be a novel frequency scanning interferometry (FSI) system that integrates a passive Fabry-Pérot (FP) delay line to overcome bandwidth limitations in high-speed, long-range distance metrology. Unlike conventional FSI systems that require high acquisition rates or active switching mechanisms, this architecture utilizes the multiple optical delays within a single FP cavity to produce a comb of modulation frequencies, with a corresponding set of delay surfaces within the measurement volume. The target self-selects the delay surfaces with the lowest modulation frequencies, thus enabling range estimation with low-bandwidth detectors and low-throughput signal processing. Delay order ambiguity is resolved by means of a dual-cavity configuration. Using a swept VCSEL laser (100 kHz repetition rate, 100 nm bandwidth), we demonstrate absolute range measurements up to 1.4 m with sub-3 ppm precision. The maximum sampling rate is a factor of >67× lower than the 54 GS s^-1 required by a conventional FSI system at this range and repetition rate, with a similar reduction in subsequent computational effort. The system is compatible with standard fiber components and scalable to high-speed, real-time metrology applications. It offers a cost-effective, compact solution for dynamic industrial environments where bandwidth, size, and power constraints typically limit FSI adoption.

Imparting vivid colors to photovoltaic devices has traditionally required sacrificing power conversion efficiency, a trade-off that limits their adoption in building-integrated photovoltaics (BIPV) and other aesthetics-driven applications. Here, we overcome this constraint by integrating short-range correlated disordered dielectric nanostructures onto high-efficiency organic-silicon heterojunction solar cells. These wavelength-scale nanospheres act dually to suppress broadband specular reflection, thereby enhancing light harvesting, and to generate coherent off-specular scattering that yields iridescent structural colors. To explore this mechanism, we developed a large-scale theoretical framework that decouples collective disorder from single-particle scattering responses, enabling quantitative prediction of the color-efficiency interplay in assemblies of more than 2000 nanoparticles. Experimentally, the iridescent device achieves a power conversion efficiency of 8.17%, compared with 7.3% for the reference device without PS nanospheres, while exhibiting high-saturation CIE 1931 color coordinates. This work demonstrates that vivid coloration does not require strong reflection, overturning the long-standing efficiency-aesthetics trade-off and opening pathways to next-generation BIPV that combine performance with visual appeal.

Excimer lasers are widely used in advanced lithography, while the anisotropic intensity distribution and spatial coherence of these sources have not been simultaneously fully incorporated in homogenizer designs. To address this issue, we propose a tunable excimer laser model based on a partially coherent flattened Gaussian beam that accurately reflects the characteristics of practical light sources. Furthermore, by combining pseudo-mode representation with the angular spectrum method, we efficiently compute the transmission of partially coherent beams through homogenizers and systematically investigate the effects of coherence length, Fresnel number, and defocusing on their performance to achieve highly uniform output beams. Finally, the accuracy and reliability of the proposed excimer laser source and homogenizer model are experimentally verified.

An integrated reconfigurable optical multiple-input multiple-output (MIMO) processor can effectively mitigate channel crosstalk in space-division multiplexing (SDM) systems in the optical domain, while significantly alleviating the power consumption, computational load, and processing latency compared with its digital signal processing (DSP) counterpart in the electrical domain. However, real-time reconfiguration of optical MIMO remains a significant challenge in transmission systems subject to time-varying channels under multiple impairments. This paper proposes a pilot-aided optical MIMO joint compensation scheme to address channel crosstalk, frequency offset (FO), and phase noise (PN) in SDM coherent optical communication systems. Frequency-domain pilot tones are embedded in digital subcarrier multiplexing (DSCM) signals to construct a composite transmission matrix that simultaneously characterizes channel crosstalk, FO, and PN. Phase shifters of Mach-Zehnder interferometers (MZIs) that compose an optical MIMO processor are dynamically controlled by an optimization algorithm to achieve optical mode decoupling, while the embedded pilot tones enable joint FO/PN compensation in the electrical domain. For an optical MIMO processor employing a cascaded structure, we introduce a staged optimization strategy and evaluate the convergence performance of various gradient algorithms, including gradient descent (GD), Nesterov's accelerated gradient (NAG), adaptive moment estimation (Adam), and Lookahead. Simulation results show that the staged strategy significantly accelerates convergence, with NAG converging in 20 iterations. For a simulated 800-Gb/s 2-mode 5-band DSCM dual-polarization (DP) 16-QAM signal transmission system, the proposed optical MIMO scheme incurs only a 0.2 dB OSNR sensitivity penalty relative to the theoretical 16-QAM limit at the 7% HD-FEC threshold.

Supercontinuum (SC) generation in bulk materials offers a versatile, broadband coherent light source for ultrafast spectroscopy and nonlinear optics. The filamentation process underlying SC generation is primarily governed by three critical parameters: input pulse energy, focusing numerical aperture, and crystal thickness. Using femtosecond pulses and sapphire crystals, we systematically investigate how these parameters affect SC energy stability. Depending on the number of pulse-splitting events, filamentation can manifest in either single- or multi-filament regimes, with the latter leading to undesirable spectral modulation and thus requiring avoidance. Our study reveals that within the single-filament regime, two distinct dynamical states can arise: a critical state, in which pulse-splitting dynamics and SC spectra evolve rapidly with increasing input pulse energy, and a steady state, which ensures optimal stability. Experimental results show that steady-state SC generation yields the highest stability, exceeding that of the driving laser. These findings deepen the physical understanding of filamentation and provide clear guidelines for parameter selection to achieve stable SC in bulk media, offering practical insights for optimizing broadband coherent sources in ultrafast applications.

We propose and experimentally demonstrate a compact hybrid-integrated multi-port multi-wavelength laser source (MP-MWL) for optical input/output (I/O) technology. A multi-wavelength high-power distributed feedback laser array (DFB LA) with slab-coupled optical waveguide (SCOW) and highly reflective and anti-reflective (HR-AR) coated facet is utilized to achieve simultaneous high-power output of multiple wavelengths. The reconstruction equivalent chirp technique provides highly precise control of the grating phase of the DFB laser and an equivalent π phase shift is introduced to provide single-longitudinal-mode lasing. Employed as a splitter and combiner network, an 8×8 multi-mode interferometer (MMI) on the passive silicon nitride photonic platform contributes to significant bandwidth enhancement. The output from the fiber array (FA) of the proposed MP-MWL has 8 fibers each carrying all 8 wavelengths, for a total of 64 addressable carriers. The photonic wire bonding technique enables the compact and efficient hybrid integration of the LA, MMI and FA. The side mode suppression ratios of all 8 wavelengths are above 42 dB at a 20°C working environment. A wavelength spacing of 100 GHz is achieved, and 87.5% of the wavelengths exhibit a deviation within ± 0.15 nm. Additionally, the relative intensity noise is below -135 dB/Hz, while the Lorentzian linewidth is 379.9 kHz. Furthermore, clear 25 Gb/s non-return-to-zero (NRZ) eye diagrams are obtained for all 64 carriers with the external lithium niobate Mach-Zehnder modulator. The proposed MP-MWL might be applied in optical I/O technology where the dense wavelength division multiplexing (DWDM) technique is required for increasing bandwidth in data centers.

We propose a scheme based on the multiplexing of heralded multiphoton sources for the generation of multiphoton Fock states. We theoretically analyze the performance of multiplexed multiphoton sources based on output-extended incomplete binary-tree multiplexers. We show that this system can be used to generate multiphoton states with considerably higher multiphoton probabilities than those that can be achieved with a single heralded multiphoton source. For multiplexed two-photon sources, we present detailed results on the optimization of the mean number of photon pairs generated in the heralded sources and the number of multiplexed units, which are relevant for the experimental realization.

Understanding the gain dynamics of amplification in rare-earth-doped silica glass fibers is crucial for developing sophisticated low-noise amplifiers and frequency combs. Recent and ongoing research efforts in these areas have specifically targeted the spectral region around 2 µm and the use of thulium-doped silica glass fibers as a broadband, power-scalable gain medium. We present a comprehensive characterization of the transfer functions of thulium ions in silica glass for emission in the spectral 2 µm region, including the magnitude and phase information. We investigated the most widespread pumping schemes: in-band pumping at 1550 nm, as well as out-of-band pumping at 790 nm. A semi-analytical model and a numerical model are developed to describe the complex energy level system of thulium ions and their associated ion-ion interactions, providing deeper insight into the influence of various parameters on the transfer functions of thulium ions in silica glass. The presented results of the transfer functions support the choice of fiber amplifier geometries and electronics to optimize noise performance.