A diffractive optical element was fabricated by monolithically integrating two volume phase-gratings (VPGs) in the bulk of a single-piece transparent material. A computer model of the diffraction generated by the double volume phase-grating (DVPG) was made with a rigorous coupled wave analysis simulator. Simulations and experiments show that the diffractive behavior of a DVPG can be controlled by arranging the relative displacement and the distance between the VPGs according to Talbot self-imaging planes. In order to diffract the total incident light, the phase accumulation in the VPGs has to be π/2, which was achieved by single-scan femtosecond laser processing of a nanocrystal doped glass as the substrate material. Ex situ microscope images of the cross-sections are presented for laser processed lines in the form of VPGs and DVPGs. The far-field diffraction of DVPGs formed by selectively located VPGs was characterized with a monochromatic 633 nm and a supercontinuum white light. Functional designs of high diffraction efficiency with potential applications in photonics were successfully fabricated in a one-step and free of chemicals process.
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http://dx.doi.org/10.1364/OE.402275 | DOI Listing |
Polymers (Basel)
January 2025
State Key Laboratory of Precision Manufacturing for Extreme Service Performance, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China.
Vibration sensors are integral to a multitude of engineering applications, yet the development of low-cost, easily assembled devices remains a formidable challenge. This study presents a highly sensitive flexible vibration sensor, based on the piezoresistive effect, tailored for the detection of high-dynamic-range vibrations and accelerations. The sensor's design incorporates a polylactic acid (PLA) housing with cavities and spherical recesses, a polydimethylsiloxane (PDMS) membrane, and electrodes that are positioned above.
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January 2025
Soreq NRC, Yavne 81800, Israel.
Fiber Bragg gratings (FBGs) inscribed by UV light and different femtosecond laser techniques (phase mask, point-by-point, and plane-by-plane) were exposed-in several irradiation cycles-to accumulated high doses of gamma rays (up to 124 MGy) and neutron fluence (8.7 × 10/cm) in a research-grade nuclear reactor. The FBG peak wavelengths were measured continuously in order to monitor radiation-induced shifts.
View Article and Find Full Text PDFMolecules
January 2025
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Anhui University, Hefei 230601, China.
Carbon-based nanomaterials with excellent electrical and optical properties are highly sought after for a plethora of hybrid applications, ranging from advanced sustainable energy storage devices to opto-electronic components. In this contribution, we examine in detail the dependence of electrical conductivity and the ultrafast optical nonlinearity of graphene oxide (GO) films on their degrees of reduction, as well as the link between the two properties. The GO films were first synthesized through the vacuum filtration method and then reduced partially and controllably by way of femtosecond laser direct writing with varying power doses.
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January 2025
School of Physics and Optoelectronic Engineering, Beijing University of Technology, Beijing 100124, China.
Gallium nitride (GaN) exhibits distinctive physical and chemical properties that render it indispensable in a multitude of electronic and optoelectronic devices. Given that GaN is a typical hard and brittle material that is difficult to machine, femtosecond laser technology provides an effective and convenient tool for processing such materials. However, GaN undergoes complex physical and chemical changes during high-power ablation, which poses a challenge to high-precision processing with controllable geometry.
View Article and Find Full Text PDFLangmuir
January 2025
Laboratory of the Intelligent Microsystem, Beijing Information Science and Technology University, Beijing 100192, China.
In this work, laser-induced graphene from kraft paper (kraft paper-LIG) was employed for the nonenzymatic electrochemical sensing of dopamine (DA). We reported the fabrication and characterization of a disposable, cost-effective, kraft-based electrochemical dopamine sensor with the sensing electrode consisting of laser-induced graphene derived from kraft paper. Kraft paper-LIG was formed by the femtosecond laser modification of kraft paper into a three-dimensional (3D) graphene arrangement.
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