Microfabrication of Three-Dimensional Structures in Polymer and Glass by Femtosecond Pulses

We report three-dimensional laser microfabrication, which enables microstructuring of materials on the scale of 0.2-1 micrometers. The two different types of microfabrication demonstrated and discussed in this work are based on holographic recording, and light-induced damage in transparent dielectric materials. Both techniques use nonlinear optical excitation of materials by ultrashort laser pulses (duration < 1 ps).Comment: This is a proceedings paper of bi-lateral Conf. (Republics of China & Lithuania) on Optoelectronics and Magnetic Materials, Taipei, May 25-26, 2002.

Nanoscale precision of 3D polymerisation via polarisation control

A systematic analysis of polarization effects in a direct write femtosecond laser 3D lithography is presented. It is newly shown that coupling between linear polarization of the writing light electric field and temperature gradient can be used to fine-tune feature sizes in structuring of photoresists at a nanoscale. The vectorial Debye focusing is used to simulate polarization effects and a controlled variation up to 20% in the linewidth is shown experimentally for the identical axial extent of the polymerised features. The revealed mechanisms are relevant for a wide range of phenomena of light-matter interaction at tight focusing in laser-tweezers and in plasmonic or dielectric sub-wavelength focusing where strong light intensity and thermal gradients coexist.Comment: 15 pages, 3 figure

Evidence of superdense aluminium synthesized by ultrafast microexplosion

At extreme pressures and temperatures, such as those inside planets and stars, common materials form new dense phases with compacted atomic arrangements and unusual physical properties. The synthesis and study of new phases of matter at pressures above 100 GPa and temperatures above 10 4 Kg-warm dense matterg-may reveal the functional details of planet and star interiors, and may lead to materials with extraordinary properties. Many phases have been predicted theoretically that may be realized once appropriate formation conditions are found. Here we report the synthesis of a superdense stable phase of body-centred-cubic aluminium, predicted by first-principles theories to exist at pressures above 380 GPa. The superdense Al phase was synthesized in the non-equilibrium conditions of an ultrafast laser-induced microexplosion confined inside sapphire (α-Al 2O 3). Confined microexplosions offer a strategy to create and recover high-density polymorphs, and a simple method for tabletop study of warm dense matter

Determination of Stokes vector from a single image acquisition

Four Stokes parameters (1852) define the polarisation state of light. Measured changes of the Stokes vector of light traversing an inhomogeneous sample are linked to the local anisotropies of absorption and refraction and are harnessed over an increasing range of applications in photonics, material, and space/earth observation. Several independent polarisation sensitive measurements are usually required for determination of the all four Stokes parameters, which makes such characterisation procedure time-consuming or requires complex setups. Here we introduce a single-snapshot approach to Stokes polarimetry in transmission by use of a 4-polarisation camera with the on-chip integrated polarisers. A quarter-waveplate was added in front of the sample and was illuminated by a linearly polarised light. This approach is demonstrated by measuring birefringence $\Delta n\sim 0.012$ of spider silk of only $\sim 6~\mu$m-diameter using microscopy, however, due to its generic nature, it is transferable to other spectral ranges and imaging applications, e.g., imaging from a fast moving satellite or drone or monitoring fast changing events such as phase transitions.Comment: 9 pages, 8 figure

AVal: an Extensible Attribute-Oriented Programming Validator for Java

International audienceAttribute Oriented Programming (@OP ) permits programmers to extend the semantics of a base program by annotating it with attributes that are related to a set of concerns. Examples of this are applications that rely on XDoclet (such as Hibernate) or, with the release of Java5's annotations, EJB3. The set of attributes that implements a concern defines a Domain Specific Language, and as such, imposes syntactic and semantic rules on the way that attributes are included in the program or even on the program itself. We propose a framework for the definition and checking of these rules for @OP that uses Java5 annotations. We define an extensible set of meta-annotations to allow the validation of @OP programs, as well as the means to extend them using a compile-time model of the program's source code. We show the usefulness of the approach by presenting two examples of its use: an @OP extension for the Fractal component model called Fraclet, and the JSR 181 for web services definitio

Three-dimensional recording by tightly focused femtosecond pulses in LiNbO₃

The authors report on a three-dimensional single-shot optical recording by 150fs pulses at 800nm wavelength in Fe doped LiNbO₃. The rewritable bits (2ₓ×2y×8zμm³) are demonstrated. The highest refractive index modulation of ∼10⁻³ per single pulse has been formed by preferential photovoltaiceffect at close to the dielectric breakdownirradiance of ∼TW/cm² and was independent of polarization (in respect to the c axis). The achievable refractive index modulation is evaluated and the recording mechanisms are discussed.One of the authors M.S. thanks the Matsumae International Foundation for the research fellowship. Another author E.G.G. acknowledges support of the Australian Research Council through its Center of Excellence

Mechanical properties and tuning of three-dimensional polymeric photonic crystals

Applied Physics LettersMechanical properties of photopolymerized photonic crystal PhC structures having woodpile and spiral three-dimensional architectures were examined using flat-punch indentation. The structures were found to exhibit a foamlike response with a bend-dominated elastic deformation regime observed at strain levels up to 10%. Numerical simulations of optical properties of these PhC structures demonstrate the possibility of achieving a substantial and reversible spectral tuning of the photonic stop gap wavelength by applying a mechanical load to the PhC

Infrared micro-sensor based on 3D photonic crystal

2015年度～2017年度 科学研究費助成事業(基盤研究(C)（一般）)研究成果報告書publishe