High performance LaAlF nanocomposite coatings prepared by a co-evaporation technique.

LaAlF nanocomposite coatings with various amounts of AlF in LaF were deposited on the fused silica substrate using double-source electron beam co-evaporation. The effects of the material composition on the chemical composition, optical properties, microstructure properties, and residual stress of these deposited coatings were investigated. The results showed that although the doping of AlF led to a reduction in the refractive index, the overall performance of the nanocomposites showed remarkable improvement.

Hybrid design scheme for enabling large-aperture diffractive achromat imaging.

Diffractive achromats (DAs) combined with image processing algorithms offer a promising lens solution for high-performance ultra-thin imagers. However, the design of large-aperture DAs that align seamlessly with image processing algorithms remains challenging. Existing sequential methods, which prioritize focusing efficiency in DAs before selecting an algorithm, may not achieve a satisfactory match due to an ambiguous relationship between efficiency and final imaging quality.

Enhanced Circular Dichroism for Achiral Sensing Based on a DNA-Origami-Empowered Anapole Metasurface.

Circular dichroism (CD) spectroscopy has been extensively utilized for detecting and distinguishing the chirality of diverse substances and structures. However, CD spectroscopy is inherently weak and conventionally associated with chiral sensing, thus constraining its range of applications. Here, we report a DNA-origami-empowered metasurface sensing platform through the collaborative effect of metasurfaces and DNA origami, enabling achiral/slightly chiral sensing with high sensitivity via the enhanced ΔCD.

Real-time synchronized monitoring for the overlap accuracy of the combining beam spot in a wavelength beam combination based on confocal planes.

Beam overlap accuracy in a wavelength beam combination system determines the beam quality and efficiency, so systematic monitoring of overlap accuracy is essential. In this work, a method of performing real-time synchronized monitoring and recording overlap accuracy for a combining beam spot is proposed. Firstly, theoretical calculations for monitoring different wavelength sub-beam positions and angular errors are established.

Group delay dispersion monitoring for computational manufacturing of dispersive mirrors.

We present a computational manufacturing program for monitoring group delay dispersion (GDD). Two kinds of dispersive mirrors computational manufactured by GDD, broadband, and time monitoring simulator are compared. The results revealed the particular advantages of GDD monitoring in dispersive mirror deposition simulations.

Production of ultra-steep dichroic filters with broad band optical monitoring.

The feasibility of using direct broad band optical monitoring control in the fabrication of the ultra-steep dichroic filters based on resonant structures is investigated. Using computational manufacturing and deposition experiments, the role of the errors self-compensation effect is clarified by comparing the results of direct broad band optical monitoring and time monitoring. The errors correlation strength of ultra-steep dichroic filter is analyzed and it shows that the correlation calculated by the current model is not strong.

Mechanisms of the Jian Pi Tiao Gan Yin in the treatment of simple obesity revealed by network pharmacology.

Background: This study sought to examine the mechanism of the Jian Pi Tiao Gan Yin in the treatment of obesity by network pharmacology.

Methods: The active components and corresponding targets of the Jian Pi Tiao Gan Yin were identified using the traditional Chinese medicine systems pharmacology database and analysis platform, and the obesity-related targets were acquired from the Online Mendelian Inheritance in Man database. The drug and disease targets were also identified.

High performance ZnS antireflection sub-wavelength structures with HfO protective film for infrared optical windows.

Antireflection sub-wavelength structures (SWSs) on ZnS were designed and ZnS SWSs with HfO protective film were prepared, and their properties in long-wave infrared applications were examined and compared to AR coatings. The SWS has good antireflection performance and exhibits less polarization sensitivity than the AR coating. At temperatures above 500 °C, the SWS with HfO protective film has a better thermal endurance property than the multilayer AR coating.

HfSiO Nanocomposite Coatings Prepared by Ion-Assisted Co-Evaporation Process for Low-Loss and High-LIDT Optics.

HfSiO nanocomposites with different SiO doping ratios were synthesized using an ion-assisted co-evaporation process to achieve dense amorphous HfSiO coatings with low loss and a high laser-induced damage threshold (LIDT). The results showed that the HfSiO nanocomposites (x ≥ 0.20) exhibited excellent comprehensive performance with a wide band gap and a dense amorphous microstructure.

Ultrabroadband Absorption Enhancement via Hybridization of Localized and Propagating Surface Plasmons.

Broadband metamaterial absorbers (MAs) are critical for applications of photonic and optoelectronic devices. Despite long-standing efforts on broadband MAs, it has been challenging to achieve ultrabroadband absorption with high absorptivity and omnidirectional characteristics within a comparatively simple and low-cost architecture. Here we design, fabricate, and characterize a novel compact Cr-based MA to achieve ultrabroadband absorption in the visible to near-infrared wavelength region.

Near-infrared broadband Si:H/SiO multilayer gratings with high tolerance to fabrication errors.

Si:H and TiO multilayer dielectric gratings (MDGs) were studied comparatively to highlight the influence of refractive indices on fabrication tolerances, including tolerances for grating width errors and cross-sectional shape errors. The fabrication tolerance of Si:H MDGs is two to four times greater than that of TiO MDGs, because the higher refractive index of Si:H has a stronger ability to restrain electric fields. It was further revealed in these studies that a Si:H MDG with positive trapezoidal errors has minor influence on high diffraction efficiency bandwidth.

Demonstration of a dual-channel two-dimensional reflection grating filter.

A dual-channel two-dimensional (2D) reflection grating filter operating around the 1.55 µm wavelength region is demonstrated, exhibiting dual-channel reflection peaks at 1.492 µm and 1.

Design and fabrication of a superior nonpolarizing long-wavelength pass edge filter applied in laser beam combining technology.

The wavelength combining technique has been widely used to increase the power scaling of lasers. The edge filter, which is nonpolarizing for wavelength, has proven to be a critical component for the combining process, and should have high spectral efficiency, high laser induced damage threshold, and excellent thermal stability. Here, we design a superior nonpolarizing long-wavelength pass edge filter using a novel depolarized initial film structure based on a tuned Fabry-Perot interference filter.

Influence of dry etching on the properties of SiO and HfO single layers.

A comparative study was performed to investigate how etching methods and parameters affect the properties of and coatings. and single layers were prepared by electron-beam evaporation (EBE), ion-beam assisted deposition (IAD), and ion-beam sputtering (IBS). Then, ion-beam etching (IBE), reactive ion etching (RIE), and inductively coupled plasma etching (ICPE) were used to study the influence of ion bombardment energy and chemical reaction on the etching rates and properties of the prepared and single layers.

Morphological and damage growth characteristics of shell-type damage of fused silica optics induced by ultraviolet laser pulses.

Under the radiation of a nanosecond pulse laser, the types of damage and damage profile of fused silica optics are closely related to the surface and subsurface defects of the component. Using the raster-scanning mode to measure the laser-induced damage threshold of fused silica optics, three different types and sizes of damage patterns are found, of which shell damage is the intermediate state and is a bridge connecting submicrometer-size damage and catastrophic damage. This paper mainly studies the mechanism and damage growth law of shell damage, analyzes the model of laser-induced shell damage, and discusses the probability and cause of shell-damage growth.

Angle-Insensitive Broadband Absorption Enhancement of Graphene Using a Multi-Grooved Metasurface.

An angle-insensitive broadband absorber of graphene covering the whole visible spectrum is numerically demonstrated, which is resulted from multiple couplings of the electric and magnetic dipole resonances in the narrow metallic grooves. This is achieved by integrating the graphene sheet with a multi-grooved metasurface separated by a polymethyl methacrylate (PMMA) spacer, and an average absorption efficiency of 71.1% can be realized in the spectral range from 450 to 800 nm.

Morphology and growth properties of nano- and submicrometer-scale initial damage sites under 355 nm wavelength pulsed laser irradiation.

The initial damage of optical elements under irradiation of a 355 nm wavelength nano-second pulsed laser below the laser-induced damage threshold mainly includes nano- and submicrometer-scale craters. The morphology and growth characteristics of such small-scale damage, which are different from those of larger-scale damage, have not been fully clarified. In this study, laser-induced nano- and submicrometer-scale initial damage of fused silica was investigated by atomic force microscope.

Reducing light scattering in high-reflection coatings through destructive interference at fully correlated interfaces.

Light scattering in quarter-wave high-reflection (QWHR) coatings with fully correlated interfaces was reduced by adding Fabry-Perot (FP) cavity structures on top of the multilayer. The properly designed FP cavity can induce destructive interference for fully correlated interfaces and reduce the scattering loss. Compared to QWHR coatings, adding one FP cavity could decrease the scattering at the near specular angles, and two FP cavities have the potential to reduce light scattering in a broad angular range.

Interface and material engineering for zigzag slab lasers.

Laser damage of zigzag slab lasers occurs at interface between laser crystal and SiO film. Although an additional HfO layer could be used to manipulate electric-field on the crystal-film interface, their high absorption and polycrystalline structure were unacceptable. SiO was then doped in HfO to suppress its crystallization and to achieve low absorption by annealing.

Contribution of angle-dependent light penetration to electric-field enhancement at nodules in optical coatings.

The influence of angle-dependent light penetration on electric-field intensity (EFI) enhancement at nodules was investigated in this Letter. An experiment consisting of 3D finite-difference time-domain simulations was conducted on two types of polarizers that prevent light penetration at a low and a high incident angular range (IAR). The EFI at the focal point region is six times lower, and the laser damage resistance is three times higher in the polarizer blocking light penetration in a high IAR.

Influence of coating thickness on laser-induced damage characteristics of anti-reflection coatings irradiated by 1064 nm nanosecond laser pulses.

The influence of coating thickness on laser-induced damage (LID) characteristics of anti-reflection (AR) coatings irradiated by 1064 nm nanosecond laser pulses was investigated. Two HfO/SiO AR coatings with different physical thicknesses, 0.7 and 2.

Research on the mechanical stability of high laser resistant coatings on lithium triborate crystal.

The thermomechanical property of the hafnium/silica antireflection (AR) coatings on lithium triborate (LBO) crystal was investigated by simulation and experiment. From the analysis of the stress and fracture toughness, it was found that the crack originated due to the high tensile stress in hafnium coating. Then we proposed the approaches of decreasing the deposition temperature and substituting the hafnium layers with alumina to improve the mechanical stability of AR coatings on LBO crystals, and cracks were effectively suppressed.

Fabrication of broadband absorbing coatings for amplified spontaneous emission suppression.

Amplified spontaneous emission (ASE) is a critical factor that limits the output power of slab lasers. To suppress the ASE effect in slab lasers, this paper proposes a metal/dielectric broadband absorbing coating between the laser gain medium and the metal heat sink to suppress ASE from zero to total internal reflection angle on the facet from inside the laser medium. Based on accurate characterization of Cr metal thin films, Cr/SiO broadband absorbing films for 1064 nm YAG slab lasers are designed and fabricated to suppress ASE.

Characterization of grain sizes and roughness of HfO single layers.

The grain sizes and their influence on the roughness of an HfO single layer prepared with ion-assisted deposition were investigated. Three methods, x ray diffractometry, atomic force microscopy, and the k-correlated power spectral density function model, were used to obtain the grain sizes in two HfO single layers with 16 and 20 nm thicknesses. X ray diffractometry showed that the grain sizes were about 7 and 9 nm, respectively, whereas the other two methods demonstrated that the grain sizes were about 14 and 16 nm.