Directly written monolithic waveguide laser incorporating a distributed feedback waveguide-Bragg grating

We report the fabrication and performance of the first C-band directly written monolithic waveguide laser (WGL). The WGL device was created in an erbium- and ytterbium-doped phosphate glass host and consisted of an optical waveguide that included a distributed feedback Bragg grating structure. The femtosecond laser direct-write technique was used to create both the waveguide and the waveguide-Bragg grating simultaneously and in a single processing step. The waveguide laser was optically pumped at approximately 980 nm and lased at 1,537 nm with a bandwidth of less than 4 pm.     

Laser-fabricated dielectric optical components for surface plasmon polaritons

Fabrication of dielectric optical components for surface plasmon polaritons (SPPs) by two-photon polymerization (2PP) is studied. This direct-write femtosecond laser technology provides a low-cost and flexible method for the fabrication and investigation of plasmonic structures and optical components. Using the 2PP technique, we fabricated narrow dielectric ridges with dimensions as small as 150 nm on metal surfaces. SPP excitation with the laser-fabricated structures and guiding along them are demonstrated.     

Unipolar resistive switching in high-resistivity Pr<Subscript>0.7</Subscript>Ca<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> junctions

We report the first demonstration of laser forward transfer using a real-time reconfigurable mask based on a spatial light modulator. The ability to dynamically change the projected beam shape and size of a coherent light source, in this case a 355-nm pulsed UV laser, represents a significant technological advancement in laser direct-write processing. The application of laser transfer techniques with adaptive control of the laser beam pattern is unique and represents a paradigm shift in non-lithographic processing. This work describes how the size and shape of an incident laser beam can be dynamically controlled in real time with the use of a digital micromirror device (DMD), resulting in laser-printed functional nanomaterials with geometries identical to those of the projected beam. For applications requiring additive non-lithographic techniques, this novel combination, which relies on the laser forward transfer of variable, structured voxels, represents a dramatic improvement in the capabilities and throughput of laser direct-write processes.     

Variable UV laser exposure processing of photosensitive glass-ceramics: maskless micro- to meso-scale structure fabrication

A novel variable UV laser processing technique was developed that enables the concurrent fabrication of structures in photosensitive glass-ceramic (PSGC) materials that range from the micro-scale to the meso-scale domains. This technique combines the advantages of direct-write volumetric laser patterning and batch chemical processing. The merged non-thermal laser fabrication approach relies on the ability to precisely and selectively alter the chemical etch rate of the PSGC by varying the laser exposure during pattern formation. The present study determined that the chemical etch rate of a commercial photosensitive glass-ceramic (Foturan^TM, Schott Corp., Germany) in dilute hydrofluoric (HF) acid is strongly dependent on the incident laser irradiance during patterning at λ=266 nm and λ=355 nm. For low laser irradiances, the etch rate ratio (R_exposed/R_unexposed) increased nearly linearly with laser irradiance. The slopes of the linear ranges of the etch rate ratios were measured to be 435.9±46.7 μm²/mW and 46.2±2.3 μm²/mW for λ=266 nm and λ=355 nm, respectively. For high laser irradiances, the measured etch rate ratio saturated at ∼30:1 with a maximum absolute etch rate of 18.62±0.30 μm/min. The maximum absolute chemical etch rate was independent of the exposure wavelength. Consequently, variation of the laser exposure during direct-write patterning permits the formation of variegated and proximal high and low aspect ratio structures on a common substrate. The results show that adjacent microstructures with aspect ratios ranging from <1:1 to ∼30:1 can be fabricated in a single, simultaneous batch chemical etch step without the need for a complex masking sequence or post-process ablation step. This new technique facilitates rapid prototype processing with pattern and component uniformity, and achieves material processing over large areas without incurring high cost. PACS 42.62.-b; 42.79.-e; 81.05.Kf; 81.20.-n     

Ultrafast laser-written dual-wavelength waveguide laser

We report the performance of a dual-wavelength waveguide laser based on a phase-modulated sampled-grating architecture fabricated using the femtosecond laser direct-write technique. The waveguide laser was written in Yb-doped phosphate glass and had a narrow linewidth (<10 pm), high signal-to-noise ratio (>60 dB), 5 mW output power per channel, and wavelength separation of 10 nm.     

Processing of micro-particles by UV laser irradiation in a field cage

An electric cage-laser micro-turning lathe was realised and applied to contact-free handling and mechanical processing of micro particles. Since particles with diameters of several micrometers cannot be fixed in mechanical chucks, an octode field cage was used to trap and rotate a single particle in a fluid without any mechanical surface contact. A pulsed nitrogen laser of high beam quality focused to about 1 μm in diameter could be adjusted independently of the cage position. The trapping forces (negative dielectrophoresis) acting on a bead of 5 to 15 μm are up to several hundred pN. This and the surrounding fluid damp down the effect of the laser pulses during bead processing. Examples demonstrating the possibilities of this technique are shown. Microsystems with high optical quality were fabricated photolithographically or by laser direct-write chemical vapor deposition (LCVD). Technical and biotechnological applications are discussed. Received: 20 October 1999 / Accepted: 27 October 1999 / Published online: 10 November 1999     

基于微结构银纳米线的透明电子皮肤器件

Transparent, flexible electronic skin holds a wide range of applications in robotics, humanmachine interfaces, artificial intelligence, prosthetics, and health monitoring. Silver nanowire are mechanically flexible and robust, which exhibit great potential in transparent and electricconducting thin film. Herein, we report on a silver-nanowire spray-coating and electrodemicrostructure replicating strategy to construct a transparent, flexible, and sensitive electronic skin device. The electronic skin device shows highly sensitive piezo-capacitance response to pressure. It is found that micropatterning the surface of dielectric layer polyurethane elastomer by replicating from microstructures of natural-existing surfaces such as lotus leaf, silk, and frosted glass can greatly enhance the piezo-capacitance performance of the device. The microstructured pressure sensors based on silver nanowire exhibit good transparency, excellent flexibility, wide pressure detection range (0-150 kPa), and high sensitivity (1.28 kPa^-1).     

Measurement of multimode coherent phonons in nanometric spaces in a homojunction-structured silicon light emitting diode

We review the recent advances in integrated quantum optical technologies, with specific emphasis on the femtosecond laser direct-write technique. We present a comparative study of the processing windows which produce low-loss waveguides in two glasses, Schott AF-45 and Corning Eagle-2000. We report the losses at wavelengths 800 and 1,550 nm, the two most critical wavelengths for quantum information science. We find the iron absorption in Eagle-2000 to be the limiting factor for propagation losses, suggesting that low Fe $^{2+}$ glasses are better suited for quantum optical science.     

Metal nanoparticle production by pulsed laser nanostructuring of thin metal films

The controllable nanostructuring of thin metal films by nanosecond UV laser pulses is introduced as a novel technique for the production of metal nanoparticles supported on a range of different oxide substrates, including indium tin oxide. This processing is performed at low macroscopic temperatures. The physical mechanisms underlying the nanostructuring are discussed and applications for these nanoparticle films, including as catalysts for nanotube/nanowire growth and in surface enhanced Raman spectroscopy measurements, are introduced.     

Three-dimensional imaging of direct-written photonic structures

Third-harmonic generation microscopy has been used to analyze the morphology of photonic structures created using the femtosecond laser direct-write technique. Three-dimensional waveguide arrays and waveguide-Bragg gratings written in fused-silica and doped phosphate glass were investigated. A sensorless adaptive-optical system was used to correct the optical aberrations occurring in the sample and microscope system, which had a lateral resolution of less than 500?nm. This nondestructive testing method creates volume reconstructions of photonic devices and reveals details invisible to other linear microscopy and index profilometry techniques.     

Laser printing of nanocomposite solid-state electrolyte membranes for Li micro-batteries

The electrochemical and mechanical properties of nanocomposite solid-state electrolyte membranes deposited using a laser direct-write technique from a suspended solution comprised of an ionic liquid (1,2-dimethyl-3-n-butylimidazolium-bis-trifluoromethanesulfonylimide)-polymer (poly(vinylidene fluoride-co-hexafluoropropylene)) matrix with dispersed nano-particles (TiO₂) are reported and discussed. These laser printed nanocomposite solid-state membranes are shown to exhibit the proper electrochemical behavior for ionic liquids while maintaining the strength and flexibility of the polymer matrix. This combination of physical properties and deposition technique makes these deposited nanocomposite membranes ideally suited for use as an electrolyte/separator in Li micro-batteries. Sample Li micro-batteries using these laser printed nanocomposite membranes have been fabricated and their charge/discharge behavior tested, demonstrating the feasibility of using these nanocomposite membranes in Li micro-battery applications.     

Atom lithography without laser cooling

Using direct-write atom lithography, Fe nanolines are deposited with a pitch of 186 nm, a full width at half maximum (FWHM) of 50 nm, and a height of up to 6 nm. These values are achieved by relying on geometrical collimation of the atomic beam, thus without using laser collimation techniques. This opens the way for applying direct-write atom lithography to a wide variety of elements.     

激光微加工技术在集成电路制造中的应用

激光微加工技术以非接触加工方式,高效率、无污染、高精度、热影响区小的优点在微电子集成电路制造中得到了广泛应用.介绍了在集成电路制造封装中采用的激光微调、激光打孔、激光清洗、激光柔性布线和激光微焊技术.     

Laser direct write of planar alkaline microbatteries

We are developing a laser engineering approach to fabricate and optimize alkaline microbatteries in planar geometries. The laser direct-write technique enables multicapability for adding, removing and processing material and provides the ability to pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc–silver oxide alkaline cells under ambient conditions. The microbattery cells exhibit 1.55-V open-circuit potentials, as expected for the battery chemistry, and show a flat discharge behavior under constant-current loads. High capacities of over 450 Ahcm^-2 are obtained for 5-mm² microbatteries. PACS 82.47.Cb; 81.16.Mk; 82.45.Fk     

Atom lithography with ytterbium beam

We successfully produced periodic ytterbium (Yb) narrow lines on a substrate using near-resonant laser light and the direct-write atom-lithography technique. The Yb atom is a promising material for nanofabrication using atom optics due to its electrical conductivity, the laser wavelength required for handling the atoms, the vapor pressure of the fabrication process, etc. The ¹⁷⁴Yb atoms collimated by Doppler cooling were channeled by the dipole force of an optical standing wave and then deposited onto a substrate. We clearly observed a grating pattern of Yb atoms fabricated on the substrate with a line separation of approximately 200 nm after examining the surface of the substrate with atomic force microscope. This is the first demonstration of nanofabrication using the atom-optical approach with Yb atoms. PACS 32.80.-t; 32.80.-Pj     

Selective processing of semiconductor nanowires by polarized visible radiation

Semiconductor nanowires have attracted intense interest due to potential applications in electronics, sensors and photonics. Introduction of dopants and their subsequent activation are essential for exploiting the electronic properties of semiconductor materials. In this work, we demonstrate pulsed laser annealing of silicon nanowires by visible radiation to be an efficient way for activating incorporated dopants and repairing implantation damage in a process that is compatible with sensitive flexible substrates. In situ electrical monitoring was used to study the laser annealing process. The absorption of laser light in SiNWs was shown to be strongly dependent on the light polarization and nanowire diameter based on finite difference time domain simulations. PACS 42.62.-b; 64.70.Nd; 78.67.n; 81.16.c     

Soda-lime glass microlens arrays fabricated by laser: Comparison between a nanosecond and a femtosecond IR pulsed laser

We present the manufacturing of microlens arrays on soda-lime glass substrates by using two different IR pulsed lasers: a nanosecond Nd:YVO₄ laser (1064 nm) and a femtosecond laser based on Ytterbium crystal technology (1030 nm). In both cases, the fabrication technique consists of the combination of a direct-write laser process, followed by a post-thermal treatment assisted by a CO₂ laser. Through the analysis of the morphological characteristics of the generated microlenses, the different physical mechanisms involved in the glass ablation process with a nanosecond and a femtosecond laser are studied. In addition, by analyzing the optical features of the microlenses, a better result in terms of the homogeneity and quality of the spot focuses are observed for those microlenses fabricated with the Nd:YVO₄ nanosecond laser. Microlens arrays with a diameter of 80 and 90 µm were fabricated.