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Stimuli responsive diffraction gratings in soft-composite materials
摘要： Diffraction gratings (DGs) are unique optical components with the capability to control and address a travelling light wave because of their micro/nanoscale periodicity. Nowadays, DGs are used in several sophisticated and high-tech applications such as spectrometers, memories, as well as in bioengineering and telecommunications. Advanced micro and nano fabrication processes enable the realization of DGs with excellent morphological and optical properties. However, realizing DGs with on-demand optical parameters is still a challenge because of the absence of reliable and cost-effective smart materials. Herein, we discuss the unique and compelling opportunities obtained by bridging materials with intrinsic flexibility (soft polymers) and re-configurability (liquid crystals (LCs)), as well as emerging fabrication procedures. Further, we present several stimuli responsive DGs used in various research fields such as sensing, biotechnology and solar energy. Lastly, in the light of flexible and reconfigurable DGs applications, we report different examples of light responsive and electro-activated, LCs based, DGs.
关键词： photolithography,liquid crystals,diffraction gratings,optics
更新于2025-09-23 15:23:52
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Nature-Inspired Quasicrystal SRG Using Fibonacci Sequences in Photo-Reconfiguration on Azo Polymer Films
摘要： In this study, we present the fabrication route of quasicrystal surface relief grating (SRG) of azopolymer. Based on photo-reconfigurable azobenzene property, various morphologies of grating patterns were inscribed on azopolymer thin-films by two-beam coupling light interference lithography (LIL) process. Multiplexing the LIL with different rotation sequence on azopolymers resulted in unusual surface structures including quasicrystal-like SRGs with Fibonacci sequences in rotational LIL. We investigated the effect of rotation sequence on the grating patterns by atomic force microscope, revealing that rotation sequence is a critical parameter determining surface structures of azopolymer films.
关键词： holographic optical elements,diffraction gratings,optical fabrication
更新于2025-09-23 15:21:21
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CMOS Nanophotonic Sensor with Integrated Readout System
摘要： The measurement of nanophotonic sensors currently requires the use of external measuring equipment for their read-out such as an optical spectrum analyzer, spectrophotometer, or detectors. This requirement of external laboratory-based measuring equipment creates a 'chip-in-a-lab' dilemma and hinders the use of nanophotonic sensors in practical applications. Making nanophotonic sensors usable in everyday life requires miniaturization of not only the sensor chip itself but also the equipment used for its measurement. In this paper, we have removed the need of external measuring equipment by monolithically integrating 1-D grating structures with a complementary metal-oxide-semiconductor (CMOS) integrated circuit having an array of photodiodes. By doing so, we get a direct electrical read-out of the refractive index changes induced when applying different analytes to grating structures. The gratings are made of CMOS compatible silicon nitride. Employing a nanophotonic sensor made of CMOS compatible material allows fabrication of the integrated sensor chip in a commercial CMOS foundry, enabling mass production for commercialization with low cost. Our results present a significant step toward transforming present laboratory-based nanophotonic sensors into practical portable devices to enable applications away from the analytical laboratory. We anticipate the work will have a major impact on technology for personalized medicine, environmental, and industrial sensing.
关键词： Diffraction gratings,nanophotonics,photodetectors,optoelectronics,sensors
更新于2025-09-23 15:21:01
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || SPECTROPHOTOMETRY/Diode Array ☆
摘要： Diode array spectrometry represents a particular approach for characterizing the result of the interaction between electromagnetic radiation and the sample, based on simultaneous measurement of light intensity over small spectral intervals having equal width. This is achieved through the following sequential stages, as schematically shown in Figs. 1 and 2D: a. interaction between the polychromatic beam and the sample; b. spatial dispersion of the transmitted (eventually reflected or emitted) radiation according to wavelength on multiple channels of equal widths, by means of a fixed optical element; c. imaging the dispersed radiation in a focal plane; and d. (quasi)simultaneous sampling of the dispersed radiation interval using photosensitive detectors, precisely positioned in the focal plane.
关键词： photodiode principle,Diode array spectrometry,concave diffraction gratings,spectrophotometry,instrumentation
更新于2025-09-23 15:21:01
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[ASME ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - San Antonio, Texas, USA (Monday 10 September 2018)] Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies - Manufacture of Lenses and Diffraction Gratings Using DLP As an Additive Manufacturing Technology
摘要： This document condenses the results obtained when 3D printing lenses and their potential use as diffraction gratings using Digital Light Processing (DLP), as an additive manufacturing technique. This project investigated the feasibility of using DLP additive manufacturing for producing custom designed lenses and gratings. DLP was identified as the preferred manufacturing technology for gratings fabrication. Diffraction gratings take advantage of the anisotropy, in additive manufacturing processes, to produce a collated pattern of multiple fringes on a substrate with completely smooth surfaces. The gratings are transmissive and were manufactured with slit separations of 10, 25 and 50 μm. More than 50 samples were printed at various build angles and mechanically treated for maximum optical transparency. The variables of the irradiance equation were obtained from photographs taken with an optical microscope. These values were used to estimate theoretical irradiance patterns of a diffraction grating and compared against the experimental 3-D printed grating. The resulting patterns were found to be remarkably similar in amplitude and distance between peaks when compared to theoretical values.
关键词： 3D printing,lenses,Digital Light Processing (DLP),additive manufacturing,diffraction gratings
更新于2025-09-23 15:21:01
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European Microscopy Congress 2016: Proceedings || Indexation of diffraction patterns for overlapping crystals in TEM thin foils - Application to orientation mappings
摘要： Application of diffraction gratings for overcoming limitations in organic light-emitting diodes (OLEDs) for displays. The study focuses on enhancing light extraction efficiency and managing color shifts in OLEDs using a novel grating design. The experimental approach involves fabricating and characterizing grating structures on OLED substrates, with results showing significant improvements in efficiency and color stability compared to conventional methods.
关键词： diffraction gratings,color shift,efficiency,OLEDs,light extraction
更新于2025-09-19 17:15:36
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High Energy and Short Pulse Lasers || Phase Manipulation of Ultrashort Soft X-Ray Pulses by Reflective Gratings
摘要： In this chapter, we discuss the use of reflective diffraction gratings to manipulate the phase of ultrashort pulses in the extreme ultraviolet (XUV) and soft X-ray spectral regions. Gratings may be used to condition the spectral phase of ultrashort pulses, e.g., to compensate for the pulse chirp and compress the pulse, similarly to what is routinely realized for visible and infrared pulses. The chirped pulse amplification technique has been already proposed for soft X-ray free-electron laser radiation; however, it requires the use of a compressor to compensate for the pulse chirp and get closer to the Fourier limit. There are fundamental differences when operating the gratings at wavelengths shorter than ≈40 nm on a broad band: (a) the gratings are operated at grazing incidence; therefore, the optical design has to be consequently tailored to this peculiar geometry; (b) the grating efficiency is definitely lower; therefore, the number of diffractions has to be limited to two. We discuss the different configurations that can be applied to the realization of a grating stretcher/compressor.
关键词： extreme ultraviolet,soft X-ray optics,ultrafast optics,diffraction gratings,chirped pulse amplification
更新于2025-09-16 10:30:52
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Efficient Mode Multiplexer for Few-Mode Fibers Using Integrated Silicon-on-Insulator Waveguide Grating Coupler
摘要： We propose a novel and highly efficient multimode waveguide grating coupler which can simultaneously launch four channels including two polarizations of the linear polarized (LP) modes, LP01 and LP11 of a step-index few-mode fiber (FMF). The waveguide grating coupler on the silicon-on-insulator (SOI) platform is based on a subwavelength structure which was optimized using the genetic optimization approach with 2-dimensional finite-difference time-domain (2-D FDTD) simulations combined with the second?order effective medium theory (EMT). Simulations predicted the coupling efficiencies to be ?4.3 dB for LP01 mode and ?5.0 dB for the LP11 mode. The design was fabricated in a multi-project wafer (MPW) run for silicon photonics. Coupling efficiency of ?4.9 dB and ?6.1 dB was experimentally demonstrated for LP01 mode and LP11 mode, respectively. The proposed mode multiplexer is entirely passive and suitable for future applications with FMFs in space-division-multiplexing (SDM) networks.
关键词： few-mode fibers,space-division multiplexing,diffraction gratings,Integrated optics
更新于2025-09-12 10:27:22
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Large-Angle, Broadband and Multifunctional Directive Waveguide Scatterer Gratings
摘要： Conventional surface-relief gratings are inefficient at deflecting normally-incident light by large angles. This limits the overall efficiency of grating-based optical instruments and also restricts their use in many applications. Here, we demonstrate a simple approach for the design of diffraction gratings that can be highly efficient for large deflection angles, while also offering additional functionality. Such gratings are composed of a unit cell comprising a vertically-oriented asymmetric slot waveguide. The unit cell shows oscillating unidirectional scattering behavior that can be precisely tuned as a function of the waveguide length. This occurs due to interference between multiple modes excited in the structure by the incident light. In contrast to metasurface-based gratings with multiple resonant sub-elements, a periodic arrangement of such non-resonant diffracting elements allows for broadband operation and a strong tolerance for variations in angle of incidence. Full-wave simulations show that our grating designs can exhibit diffraction efficiencies ranging from 94% for a deflection angle of 47? to 80% for deflection angle of 80?. To demonstrate the multifunctionality of our approach, we also demonstrate a flat polarization beamsplitter and a polarization insensitive grating.
关键词： directional scattering,slot waveguides,diffraction gratings,metagratings,bianisotropy
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - GaSb-Based 2.55 μm External Cavity Diode Lasers Employing Ruled Diffraction Gratings and External Silicon Photonics Vernier Reflectors
摘要： Important environmental gases, such as H2S, C2H4, CH4, CO, CO2, N2O, and H2O, have strong absorption lines in the 2-3 μm wavelength range. Tunable external cavity diode lasers (ECDLs) present an attractive option for the spectroscopic detection of these gases, because of their broad tuning range, and the possibility to achieve high spectral resolution and sensitivity, due to much higher spectral power density compared to broadband sources [1]. Here we report on the implementation of two tunable ECDL configurations: one where wavelength selection is ensured by a ruled reflective diffraction grating (Littrow configuration), and one based on a tunable silicon photonic reflector chip exploiting the Vernier effect between two ring resonators. In both setups, the gain elements consisted of 3 mm-long reflective semiconductor optical amplifiers (RSOAs), based on GaSb technology and designed to have single-transverse-mode with a gain peak around 2.55 μm. The quantum well structure of the RSOA chips are similar to the superluminescent diodes (SLDs), we recently reported in reference [2], but have facet coatings designed for ECDL-use.
关键词： GaSb,external cavity diode lasers,2.55 μm,ruled diffraction gratings,silicon photonics Vernier reflectors
更新于2025-09-12 10:27:22