Improvements to the anti-drone lidar technology make it a promising alternative to the pricey EO/IR and active SWIR cameras employed in counter-UAV systems.

A continuous-variable quantum key distribution (CV-QKD) system relies on the data acquisition process to generate secure secret keys. Data acquisition methods, in their typical form, assume the channel's transmittance remains unchanged. Quantum signal transmission in a free-space CV-QKD channel is accompanied by fluctuating transmittance, a characteristic that invalidates the efficacy of the pre-existing methods. Our proposed data acquisition scheme, in this paper, relies on a dual analog-to-digital converter (ADC). This data acquisition system, designed for high precision, incorporates two ADCs operating at the same frequency as the system's pulse repetition rate, alongside a dynamic delay module (DDM). It corrects for transmittance variations through the simple division of ADC data. Simulation and proof-of-principle experimental validation demonstrate the scheme's effectiveness in free-space channels, enabling high-precision data acquisition, even under conditions of fluctuating channel transmittance and extremely low signal-to-noise ratios (SNR). Subsequently, we detail the direct use cases for the proposed scheme in a free-space CV-QKD system and examine their viability. This approach holds substantial importance for enabling both the experimental implementation and practical application of free-space CV-QKD systems.

Femtosecond laser microfabrication quality and precision are being explored through the use of sub-100 femtosecond pulses. However, the application of these lasers at pulse energies typical for laser fabrication processes is known to lead to the distortion of the beam's temporal and spatial intensity profile due to nonlinear propagation effects in air. JNJ77242113 The distortion in the material makes it difficult to quantify the eventual crater configuration produced by the laser ablation process. Nonlinear propagation simulations were leveraged in this study to develop a method for quantitatively determining the ablation crater's shape. A thorough investigation revealed that calculations of ablation crater diameters, using our method, were in excellent quantitative agreement with experimental data for several metals, over a two-orders-of-magnitude variation in pulse energy. A clear quantitative correlation was observed between the simulated central fluence and the depth of ablation in our investigation. These proposed methods are predicted to improve the controllability of laser processing, particularly for sub-100 fs pulses, extending their practical utility across a broad range of pulse energies, including those with nonlinearly propagating pulses.

Nascent data-intensive technologies are demanding the implementation of low-loss, short-range interconnections, whereas current interconnects exhibit substantial losses and limited aggregate data throughput, stemming from a lack of efficient interfaces. We report on a 22-Gbit/s terahertz fiber link, where a tapered silicon interface acts as a coupling component between the dielectric waveguide and hollow core fiber. Our study of hollow-core fibers' fundamental optical properties included fibers with core diameters measuring 0.7 mm and 1 mm. A 10 cm fiber within the 0.3 THz band demonstrated a coupling efficiency of 60% alongside a 3-dB bandwidth of 150 GHz.

The coherence theory for non-stationary optical fields informs our introduction of a fresh category of partially coherent pulse sources, featuring the multi-cosine-Gaussian correlated Schell-model (MCGCSM), and subsequently provides the analytic solution for the temporal mutual coherence function (TMCF) of an MCGCSM pulse beam navigating dispersive media. The dispersive media's effect on the temporally averaged intensity (TAI) and the temporal coherence degree (TDOC) of the MCGCSM pulse beams is investigated numerically. Source parameter control dictates the transformation of a primary pulse beam into a multi-subpulse or flat-topped TAI distribution as the beam propagates across increasing distances, as demonstrated by our results. Furthermore, if the chirp coefficient is below zero, the MCGCSM pulse beams propagating through dispersive media exhibit characteristics indicative of two self-focusing processes. The physical significance of two self-focusing processes is examined and clarified. This paper's findings pave the way for new applications of pulse beams, including multi-pulse shaping, laser micromachining, and advancements in material processing.

Electromagnetic resonance phenomena, known as Tamm plasmon polaritons (TPPs), manifest at the juncture of a metallic film and a distributed Bragg reflector. Surface plasmon polaritons (SPPs) contrast with TPPs, which display both cavity mode properties and the attributes of surface plasmons. A detailed investigation into the propagation properties of TPPs is presented in this work. JNJ77242113 Directional propagation of polarization-controlled TPP waves is enabled by nanoantenna couplers. Asymmetric double focusing of TPP waves results from the integration of nanoantenna couplers and Fresnel zone plates. Nanoantenna couplers arranged in a circular or spiral form are effective in achieving the radial unidirectional coupling of the TPP wave. This configuration's focusing ability exceeds that of a single circular or spiral groove, with the electric field intensity at the focus amplified to four times. In terms of excitation efficiency and propagation loss, TPPs outperform SPPs. The numerical study highlights the considerable promise of TPP waves in integrated photonics and on-chip devices.

A compressed spatio-temporal imaging framework, enabling the simultaneous achievement of high frame rates and continuous streaming, is proposed, incorporating the functionalities of time-delay-integration sensors and coded exposure. Due to the absence of supplementary optical encoding components and the associated calibration procedures, this electronic modulation approach leads to a more compact and reliable hardware configuration when contrasted with current imaging methodologies. By using intra-line charge transfer, a super-resolution is obtained in both the temporal and spatial dimensions, leading to a frame rate increase to millions of frames per second. Along with the forward model, possessing post-adjustable coefficients, and two subsequently-developed reconstruction techniques, the post-interpretation of voxels gains adaptability. Conclusive evidence for the proposed framework's effectiveness is provided through both numerical simulations and proof-of-concept experiments. JNJ77242113 The proposed system effectively tackles imaging of random, non-repetitive, or extended events by offering a long time span of observation and adaptable voxel analysis post-interpretation.

We introduce a five-mode, twelve-core fiber, possessing a trench-assisted structure that incorporates a low refractive index circle and a high refractive index ring (LCHR). A 12-core fiber is structured with a triangular lattice arrangement. Using the finite element method, the proposed fiber's properties are simulated. The numerical results show a worst-case inter-core crosstalk (ICXT) of -4014dB/100km, falling short of the -30dB/100km target. The effective refractive index difference between LP21 and LP02 modes now stands at 2.81 x 10^-3 after incorporating the LCHR structure, which suggests their distinct separation. The presence of LCHR results in a reduction of dispersion for the LP01 mode, amounting to 0.016 ps/(nm km) at a wavelength of 1550 nm. The core's relative multiplicity factor, which can be as high as 6217, demonstrates its considerable density. The space division multiplexing system's fiber transmission channels and capacity can be amplified by utilizing the proposed fiber.

Photon-pair sources, especially those engineered using thin-film lithium niobate on insulator technology, hold a promising position in the advancement of integrated optical quantum information processing. A source of correlated twin photon pairs, generated by spontaneous parametric down conversion within a periodically poled lithium niobate (LN) waveguide integrated into a silicon nitride (SiN) rib loaded thin film, is reported. The wavelength of the generated correlated photon pairs, centered around 1560 nanometers, dovetails seamlessly with contemporary telecommunications infrastructure, displaying a vast 21 terahertz bandwidth and a luminance of 25,105 pairs per second per milliwatt per gigahertz. With the Hanbury Brown and Twiss effect as the basis, we have also shown heralded single-photon emission, achieving an autocorrelation g²⁽⁰⁾ of 0.004.

Nonlinear interferometers incorporating quantum-correlated photons have been instrumental in achieving enhancements in optical characterization and metrology. Gas spectroscopy, particularly important for observing greenhouse gas emissions, analyzing breath samples, and industrial uses, is facilitated by these interferometers. Gas spectroscopy's enhancement is facilitated by the strategic deployment of crystal superlattices, as illustrated here. Interferometer sensitivity increases with the number of cascaded nonlinear crystals, each contributing to the overall measurement sensitivity. Specifically, the enhanced sensitivity manifests in the maximum intensity of interference fringes, correlating with low concentrations of infrared absorbers; however, interferometric visibility measurements show enhanced sensitivity at high concentrations. Subsequently, a superlattice's role as a versatile gas sensor is established by its ability to operate by measuring diverse observables of practical significance. Our strategy, we believe, provides a compelling avenue for enhanced quantum metrology and imaging, utilizing nonlinear interferometers and correlated photon pairs.

In the 8- to 14-meter atmospheric transparency range, high-bitrate mid-infrared links have been successfully implemented, utilizing both simple (NRZ) and multi-level (PAM-4) data encoding techniques. The components of the free space optics system are unipolar quantum optoelectronic devices: a continuous wave quantum cascade laser, an external Stark-effect modulator, and a quantum cascade detector, which all operate at room temperature.