Growth of single and multilayer sesquioxide crystal films for lasing applications via pulsed laser deposition

Sesquioxides, materials of the form RE2O3 (RE: rare earth), are of great interest for lasing applications. These materials offer high thermal conductivities, are mechanically stable, can easily be doped with various rare earth ions and are optically isotropic. Members of the sesquioxide family have the same crystal structure but differing refractive indices, and hence are ideal candidates for multilayer as well as single film growth. Sesquioxides can be challenging to grow from the melt, however, due to their high melting points (>2400 °C)

Precision nanoscale domain engineering of lithium niobate via UV laser induced inhibition of poling

Continuous wave ultraviolet (UV) laser irradiation at lambda=244 nm on the +z face of undoped and MgO doped congruent lithium niobate single crystals has been observed to inhibit ferroelectric domain inversion. The inhibition occurs directly beneath the illuminated regions, in a depth greater than 100 nm during subsequent electric field poling of the crystal. Domain inhibition was confirmed by both differential domain etching and piezoresponse force microscopy. This effect allows the formation of arbitrarily shaped domains in lithium niobate and forms the basis of a high spatial resolution micro-structuring approach when followed by chemical etching

Ultra-smooth lithium niobate micro-resonators by surface tension reshaping

Thermal treatment of micro-structured lithium niobate substrates at temperatures close to, but below the melting point, allows surface tension to reshape a preferentially melted surface zone [1] of the crystal to form ultra-smooth single crystal toroidal or spherical structures. Such structures, an example of which is shown in figure 1, are suitable for the fabrication of photonic micro-resonators with low scattering loss. The thermally treated material maintains its single crystal nature after the thermal treatment because the bulk remains solid throughout the process acting as seed during the recrystallization process which takes place during the cooling stage. The single crystal nature of the reshaped material has been verified by piezoresponse force microscopy, Raman spectroscopy and chemical etching. The inherent properties of lithium niobate crystals (optically nonlinear, piezoelectric and electro-optic) makes the resultant micro-resonator extremely suitable for sensing applications, for the production of micro-lasers (if doped with Er or Nd), for nonlinear frequency generation and finally for switching/modulation and tunable spectral filtering in optical telecommunications. The transformation of the initial surface micro-structures to the resulting resonator structure is a temperature dependent process as the surface tension acts on the surface melted layer of the crystal, Experimental investigation and modelling of the thermal treatment as well as investigation of the performance of these microresonators is underway to establish full control of the fabrication process for practical applications

A Study of Expert Systems Using AURA

Many computational biologists would agree that, had it not been for random modalities, the deployment of online algorithms might never have occurred [19]. In this work, we demonstrate the understanding of the producer-consumer problem, which embodies the natural princi- ples of artificial intelligence. In order to achieve this aim, we use atomic configurations to validate that IPv4 can be made electronic, lossless, and low-energy

Apparatus to control and visualize the impact of a high-energy laser pulse on a liquid target

We present an experimental apparatus to control and visualize the response of a liquid target to a laser-induced vaporization. We use a millimeter-sized drop as target and present two liquid-dye solutions that allow a variation of the absorption coefficient of the laser light in the drop by seven orders of magnitude. The excitation source is a Q-switched Nd:YAG laser at its frequency-doubled wavelength emitting nanosecond pulses with energy densities above the local vaporization threshold. The absorption of the laser energy leads to a large-scale liquid motion at timescales that are separated by several orders of magnitude, which we spatiotemporally resolve by a combination of ultra-high-speed and stroboscopic high-resolution imaging in two orthogonal views. Surprisingly, the large-scale liquid motion at upon laser impact is completely controlled by the spatial energy distribution obtained by a precise beam-shaping technique. The apparatus demonstrates the potential for accurate and quantitative studies of laser-matter interactions.Comment: Submitted to Review of Scientific Instrument

Efficient amplification of a single-mode laser diode via photorefractive beam combination using an injection locked laser diode array pump

Powers in excess of 100mW have been obtained in a near-diffraction-limited, single-mode laser-diode output by photorefractive two-beam coupling in BaTiO3, using an injection-locked 1W diode-laser array as the pump source. Signal gains of as much as 8.1 are obtained, corresponding to pump transfer efficiencies of 49%. Calculations suggest that powers as high as 225mW should be obtainable, given suitable antireflection-coated optics

Space station common module network topology and hardware development

Conceptual space station common module power management and distribution (SSM/PMAD) network layouts and detailed network evaluations were developed. Individual pieces of hardware to be developed for the SSM/PMAD test bed were identified. A technology assessment was developed to identify pieces of equipment requiring development effort. Equipment lists were developed from the previously selected network schematics. Additionally, functional requirements for the network equipment as well as other requirements which affected the suitability of specific items for use on the Space Station Program were identified. Assembly requirements were derived based on the SSM/PMAD developed requirements and on the selected SSM/PMAD network concepts. Basic requirements and simplified design block diagrams are included. DC remote power controllers were successfully integrated into the DC Marshall Space Flight Center breadboard. Two DC remote power controller (RPC) boards experienced mechanical failure of UES 706 stud-mounted diodes during mechanical installation of the boards into the system. These broken diodes caused input to output shorting of the RPC's. The UES 706 diodes were replaced on these RPC's which eliminated the problem. The DC RPC's as existing in the present breadboard configuration do not provide ground fault protection because the RPC was designed to only switch the hot side current. If ground fault protection were to be implemented, it would be necessary to design the system so the RPC switched both the hot and the return sides of power

Magnetic microscopy/metrology potential of metamaterials using nanosized spherical particle arrays

Techniques for imaging and characterizing magnetic samples have been widely used in many areas of research involving magnetic materials. Nowadays, magnetic microscopy techniques play a critical role in characterizing magnetic thin film structures. In considering the various techniques, optical techniques offer some unique advantages over alternative techniques (e.g. MFM), as they are least affected by magnetic noise and, for the same underlying reasons, have also proven to be more suitable for "high speed" magnetization measurements of magnetization dynamics, which are increasingly important in many of today's research scopes. At the same time, development of metamaterials are opening the doors for newly behaving materials, such as those demonstrating negative refractive index, potentially useful in a variety of applications, such as imaging. Metamaterials deploying arrays of silicon particles, and even alternating silicon particles and split ring resonators have recently been shown to demonstrate interesting behavior, such as negative magnetic susceptibility and large resonant peaks in the Terahertz regime. Such high frequencies offer the potential bandwidth of extraordinarily fast dynamics, which are increasingly being generated in magnetic materials, for example, in optically-induced demagnetization and all-optical magnetic recording. Here, initial investigations toward ultra high-speed imaging and/or information extraction from magnetic samples is discussed considering metamaterials deploying mainly spherical particle arrays. In addition to the frequency spectrums of the system, the response of the system to external magnetic fields and background permeability changes due to external fields are investigated. Our results suggest a significant potential of metamaterials for use in probing information from magnetic materials

Ordered nano-scale domains in lithium niobate single crystals via phase-mask assisted all-optical poling

We report the formation of directionally-ordered nanoscale surface domains on the +z face of undoped congruent lithium niobate single crystals by using UV illumination through a phase mask with an energy fluence between ~90mj/cm2 and 150 mJ/cm2 at lambda = 266 nm. We clearly show here that the UV-induced surface ferroelectric domains nucleate and then propagate along the maxima of laser intensity produced by the phase mask, thus enabling a degree of control over this all-optical poling process. Acid etching of the illuminated crystal faces was employed to reveal the induced domain nature and the spatial structure of the formed nanoscale domains