Multilayer Diffraction Research Articles

10.8 kW spectral beam combination of eight all-fiber superfluorescent sources and their dispersion compensation.

We report an 8-element spectral beam combination of Yb-doped all fiber superfluorescent sources around 1070 nm wavelength. Each source consists of a 60 mW front-end and a 1.5 kW three-stage fiber amplifier chain. The eight output beamlets are spectrally combined using a home-made polarization-independent multilayer dielectric reflective diffraction grating. 10.8 kW output power is achieved with an efficiency of 94%. Besides, both theoretical and experimental studies of dual grating dispersion compensation scheme have been performed, which is proved to be a prospective way for high brightness spectral beam combination.

Electron-phonon equilibration in laser-heated gold films

By irradiating a thin metal foil with an intense short-pulse laser, we have created a uniform system far from equilibrium. The deposited energy is initially deposited only within the electronic subsystem, and the subsequent evolution of the system is determined by the details of the electron-phonon coupling. Here, we measure the time evolution of the lattice parameter through multilayer Bragg diffraction and compare the result to classical molecular dynamic simulations to determine the lattice temperature. The electron-ion coupling constant for gold is then determined by comparison with the evolution of a two-temperature electron-phonon system.

Nanostructural Colouration in Malaysian Plants: Lessons for Biomimetics and Biomaterials

Plant tissues include leaves, flower petals, and fruits. These can provide us with variety of design inspirations. Biomimetics allows us to learn from nature and transfer the knowledge we gain from studying sophisticated and amazing biological structures, materials and processes to engineering and the arts. The microstructures of morphology and anatomy of plant tissue have potential applications in technology through bioinspired design, which can mimic the properties found in nature or use them as inspiration for alternative applications. Many applications have been developed as a result of studying physical properties of plant tissues. Structural colours, for example, have been applied in the design of thin films both with regard to single or multilayer thin film interference, scattering, and diffraction gratings. Iridescent, metallic, or greyish colouration found naturally in plants is the result of physical structures or physical effects and not pigmentation. Phenotypical appearance of plants with structural colouration in tropical Malaysia is correlated with environmental parameters such as location (shady understory rainforest, sunny conditions) and altitude (highlands, lowlands). Various examples of bioinspired technical innovations with structural colours highlight the importance of inspiration by structural colours in living nature.

极紫外光刻含缺陷多层膜衍射谱仿真简化模型

极紫外光刻含缺陷多层膜衍射谱仿真简化模型

Joint application of the incomplete Galerkin method and scattering matrix method for modeling multilayer diffraction gratings

A mathematical model of wave diffraction from a one-dimensional multilayer periodic grating is considered. A rigorous mathematical statement is given for the problem where partial radiation conditions are used for domain confinement. A complete formulation of the numerical algorithm based on a combination of the incomplete Galerkin method and the scattering-matrix method is presented. The algorithm’s convergence rate and computational complexity are analyzed and the optimal values of the computational parameters are recommended.

Influence of microstructure on optical behaviour of freshwater cultured pearls

The relationship between optical behaviour and microstructure of pearl was studied by laser scanning confocal microscopy, high resolution scanning electron microscopy and atomic force microscopy. There are three optical effects in pearls, namely, the reflection–diffraction effect, a chromatic diffusion halo and the whispering gallery effect. From the structure observation for pearls, we proposed that the first optical effect exhibited by pearls is dominated by the surface diffuse reflection. In addition, the multilayer interference and diffraction have little contribution. With delicate observation for the structure of pearl by an atomic force microscope, it is revealed that the polygon platelets of pearl are not single crystals but nanograins of aragonite in the network of organic matrix, which is responsible for the chromatic diffusion halo. As for the third optical effect, it originates from the stratification structure, which is composed of aragonite platelets. When the light falls on the surface of the pearl, it will travel along the laminations of its structure rather than through the whole pearl, so the rim of the pearl is bright even if no light falls on the surface directly.

Conical diffraction by multilayer gratings: a recursive integral equation approach

The paper is devoted to an integral equation algorithm for studying the scattering of plane waves by multilayer diffraction gratings under oblique incidence. The scattering problem is described by a system of Helmholtz equations with piecewise constant coefficients in ℝ2 coupled by special transmission conditions at the interfaces between different layers. Boundary integral methods lead to a system of singular integral equations, containing at least two equations for each interface. To deal with an arbitrary number of material layers we present the extension of a recursive procedure developed by Maystre for normal incidence, which transforms the problem to a sequence of equations with 2×2 operator matrices on each interface. Necessary and sufficient conditions for the applicability of the algorithm are derived.

Extension of Reflectance and Transmission Coefficient Matrix to C-method for study of periodic multilayer system

The C-method is one of the most efficient and versatile method designed for diffraction gratings. The boundary conditions of the grating can be greatly simplified when the coordinate systems coincide with the surfaces of the grating. Reflectance and Transmission Coefficient Matrix (RTCM) with clearly physical concept is a powerful propagation algorithm proposed for steady and fast calculation of multilayer gratings. In this paper, the C-method is extended to treat the multilayer diffraction grating with the identical or nonidentical surface shapes. Numerical examples including diffraction efficiencies of both dielectric and metallic grating are presented. In addition, the excellent convergence for various adjacent-heights and diffracted orders of our propagation algorithm for TE and TM polarizations is also included.

Multifunctional Lipid Multilayer Stamping

Nanostructured lipid multilayers on surfaces are a promising biofunctional nanomaterial. For example, surface-supported lipid multilayer diffraction gratings with optical properties that depend on the microscale spacing of the grating lines and the nanometer thickness of the lipid multilayers have been fabricated previously by dip-pen nanolithography (DPN), with immediate applications as label-free biosensors. The innate biocompatibility of such gratings makes them promising as biological sensor elements, model cellular systems, and construction materials for nanotechnology. Here a method is described that combines the lateral patterning capabilities and scalability of microcontact printing with the topographical control of nanoimprint lithography and the multimaterial integration aspects of dip-pen nanolithography in order to create nanostructured lipid multilayer arrays. This approach is denoted multilayer stamping. The distinguishing characteristic of this method is that it allows control of the lipid multilayer thickness, which is a crucial nanoscale dimension that determines the optical properties of lipid multilayer nanostructures. The ability to integrate multiple lipid materials on the same surface is also demonstrated by multi-ink spotting onto a polydimethoxysilane stamp, as well as higher-throughput patterning (on the order of 2 cm(2) s(-1) for grating fabrication) and the ability to pattern lipid materials that could not previously be patterned with high resolution by lipid DPN, for example, the gel-phase phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or the steroid cholesterol.

Nanoindentation probing of high-aspect ratio pillar structures on optical multilayer dielectric diffraction gratings

ABSTRACTWe measure the mechanical response of optical multilayer dielectric (MLD) diffraction gratings, geometries which are constrained in only one transverse direction but free in the other, using nanoindentation. The results are explained using a stress-strain model, which reveals a uniaxial yield stress of 4.1- 4.6 GPa and predicts a similar dependence of yield stress on loads for both fully-elastic and fully-plastic solutions. Following R. Hill’s model of an expanding cavity under internal pressure, we show that the indentation response of the high-aspect ratio “pillar” geometry can be expressed in terms of uniaxial yield stress rather than material hardness.

宽光谱大视场角的高衍射效率多层衍射元件

宽光谱大视场角的高衍射效率多层衍射元件

Nanoindentation of high-aspect ratio pillar structures on optical multilayer dielectric diffraction gratings

The mechanical response of optical multilayer dielectric (MLD) diffraction gratings has been studied using nanoindentation. The results are interpreted using a stress-strain model, which reveals a uniaxial yield stress of 4.1 GPa. It is shown that the indentation response of the high-aspect ratio “pillar” geometry (constrained in one transverse direction but free in the other) can be expressed in terms of yield stress rather than material hardness.

Analysis of a Gradient Index Metamaterial Blazed Diffraction Grating

The equivalent of a blazed diffraction grating can be formed from an array of metamaterial elements arranged so as to produce a linear gradient in the effective refractive index. By spreading the gradient over a multiwavelength distance, and repeating the pattern many times, a gradient index (GRIN) diffraction grating is formed. Using lithographically patterned, metallic metamaterial elements, dozens of distinguishable phase levels can be implemented by slightly modifying the design of each successive metamaterial element. We analyze here a multilayer metamaterial diffraction grating designed for operation at 10.6 μm, exploring the impact of material losses and impedance mismatch on the diffraction efficiency.

Diffraction property of broadband metal multi-layer dielectric gratings based on rigorous coupled-wave analysis

The rigorous coupled-wave analysis technique for describing the diffraction of metal multi-layer diffraction grating (MMDG) is built. Formulation for a stable and efficient numerical implementation of diffraction efficiency is presented for MMDG with TE polarization. With the merit function of the -1 order diffraction efficiency higher than 97% and working bandwidth, the parameters of MMDG are optimized to achieve broadband. The bandwidths used for 800 nm and 1053 nm can be 130 nm and 150 nm respectively. The manufacture latitude and the effective incident angle for the optimized structure of MMDG are discussed. The optimized grating should be useful for chirped pulse compress.

Large area high efficiency broad bandwidth 800 nm dielectric gratings for high energy laser pulse compression

We have demonstrated broad bandwidth large area (229 mm x 114 mm) multilayer dielectric diffraction gratings for the efficient compression of high energy 800 nm laser pulses at high average power. The gratings are etched in the top layers of an aperiodic (Nb0.5Ta0.5)2O5-SiO2 multilayer coating deposited by ion beam sputtering. The mean efficiency of the grating across the area is better than 97% at the center wavelength and remains above 96% at wavelengths between 820 nm and 780 nm. The gratings were used to compress 5.5 J pulses from a Ti:sapphire laser with an efficiency above 80 percent.

Improved method for computing of light-matter interaction in multilayer corrugated structures: comment

The method recently proposed by Korovin [J. Opt. Soc. Am. A25, 394 (2008)] for modeling multilayer diffraction gratings is in fact the well-known Rayleigh-Fourier method. Many remarks in the above reference in comparing the proposed method and the C method are biased and inaccurate.

Diffraction property of multi-layer dielectric gratings studied by rigorous coupled-wave analysis

The rigorous coupled-wave analysis technique for describing the diffraction of multi-layer diffraction grating (MDG) is put forward. Formulations for a stable and efficient numerical implementation of diffraction efficiency are presented for MDG for TE polarization and Littrow angle. With the merit function of the -1 order diffraction efficiency higher than 96%, the parameters of MDG are optimized for HfO2 and SiO2 top layers, respectively. Numerical calculation indicates that a larger grating parameter range can be obtained with HfO2 rather than the SiO2 on the top. The manufacture tolerance and the effective incident angle for the optimized structure of MDG are discussed in the end.

Development and Evaluation of a Binary Grating consisting of Multi-layer Diffraction

The binary hologram masters with multi-layer refractive index were developed and evaluated in their characteristics. The chirped diffraction grating was fabricating by electron-beam lithography. The design of metallic binary multi-layer gratings were successfully fabricated by excellent polarization separation elements (Hologram Color Filter). The obtained gratings designed were formed by binary metallic microstructures and deflected the incoming light into a certain direction with theoretical efficiency of over 90%.

Multilayer phase-only diffraction gratings: Fabrication and application to extreme ultraviolet optics

The use of phase-only diffractive devices has long played an important role in advanced optical systems in varying fields. Such devices include gratings, diffractive and holographic optical elements, diffractive lenses, and phase-shift masks for advanced lithography. Extending such devices to the increasingly important regime of extreme ultraviolet (EUV) wavelengths, however, is not trivial. Here, the authors present an effective fabrication and etch process enabling high-resolution patterning of Mo∕Si multilayers for use in EUV phase devices, providing another method for fabrication of high numerical aperture diffractive devices or high-resolution EUV phase shift masks.

Fabrication of photonic devices in nanostructured glasses by femtosecond laser pulses

Focused femtosecond laser pulses have been used to modify the optical properties of glass doped with CdSxSe1-x nanocrystals. Large positive refractive index changes have been observed and exploited for the fabrication of photonic devices. In particular, we report on highly confining optical waveguides and single and multi-layer volume diffraction gratings.