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The reaction of aerosol droplets of the organoborate reagent (MeO)3B, suspended in nitrogen, with gaseous ammonia in a flight tube heated to 800−1500 °C was used to produce, in high yield, spherical morphology precursor powders BNxOyCz that contain decreasing amounts of oxygen and carbon as the process temperature and mole fraction of ammonia increased. Subsequent static nitridation of the precursor powder under ammonia gave spherical morphology BN powders with low (

We studied mutual injection locking of two individual continuous-wave Nd:YVO/sub 4/ lasers that were coupled through an external section. The two lasers lased at the same wavelength with a stable output power and interference fringes with high contrast ratio in the combined beam profile showed good mutual coherence of the two lasers. Mutual injection locking was also achieved without active stabilization for individual lasers with a large cavity length difference and low Q-factors. The calculated combined output power under symmetric pumping agreed with the experimental results. Even when output couplings of individual lasers are not optimized, the output coupling of the combining section can be optimized to make the extracted power very close to the sum of maximum powers that can be extracted from individual free running lasers under optimal output coupling.

The azidoborazines [Me(3)N(3)B(2)(Me)(2)B(N(3))] and [H(3)N(3)B(3)(N(3))(3)] were prepared from the combination of Me(3)SiN(3) and the chloroborazines [Me(3)N(3)B(2)(Me)(2)BCl] and (H(3)N(3)B(3)Cl(3)). The compounds have been characterized by analytical and spectroscopic methods. The molecular structure of [H(3)N(3)B(3)(N(3))(3)] has been confirmed by single-crystal X-ray diffraction techniques: triclinic space group Ponemacr; with a = 8.579(1) Å, b = 9.182(1) Å, c = 12.043(1) Å, alpha = 104.62(1) degrees, beta = 90.26(1) degrees, gamma = 110.74(1) degrees, and Z = 4. The thermal behavior of the azides have been examined by TGA/DTA. The explosion sensitivity of [H(3)N(3)B(3)(N(3))(3)], which contains 82.58% nitrogen by weight, has been accessed by drop weight impact, spark, and friction tests. These measurements indicate that [H(3)N(3)B(3)(N(3))(3)] is a relatively sensitive explosive. The Staudinger reactivity of the azides with Ph(3)P was examined, and [H(3)N(3)B(3)(N(3))(3)] was found to produce [Ph(3)P=NH(2)](N(3)). The molecular structure of this compound was determined by single-crystal X-ray diffraction techniques: orthorhombic space group P2(1)2(1)2(1) with a = 10.649(2) Å, b = 11.737(3) Å, c = 13.364(4) Å, alpha = beta = gamma = 90 degrees, Z = 4.

An aerosol-based synthesis is described that uses N,N-dimethylformamide solutions of boric acid as the aerosol feedstock and NH3 as a nitriding atmosphere for the preparation of hollow spherical morphology BN particles in the size range 1−5 μm. These particles display unusually high surface areas (500−1400 m2/g) and microporosity.

The U.S. Army Research Laboratory (ARL) is the Army's premier laboratory for land forces. The Army relies on ARL for scientific discoveries, technological advances, and analyses that enable capabilities a future Army will need to persevere over adversaries. Although a relatively young organization that will celebrate 25 years of the discovery, innovation, and transition of science and technology in October 2017, ARL has already had significant impact in a wide range of scientific and technological disciplines. In this paper, we highlight some of its past and recent achievements in optics and photonics.

The transient response for beam fanning in photorefractive tungsten bronze crystals with an applied electric field and a focused laser beam is studied. Response times on the order of 1 ms for an incident power of 1 mW observed for incident beams focused to a 30 μm diameter in the crystal. This improved response time is accomplished without the significant reduction in the magnitude of the photorefractive effect normally observed for focused beams.

Aminochlorophosphanylboranes, (R2N)B(Cl)P(SiMe3)2 (1a — d) and (R2N)B(Cl)PH2 (2a — d), are obtained from elimination reactions between aminochloroboranes and LiP(SiMe3)2 and LiPH2, respectively. Selected reaction chemistry of (i1-Pr2N)B(Cl)P(SiMe3)2] (1a) with NH3, Me3SiN3, Cr(CO)5 · NMe3, and W(CO)5 · NMe3 is described. The azide (i1-Pr2N)B(N3)P(SiMe3)2 (12a) is stable at 25°C; however, thermolysis at 80°C provides a novel six-membered ring compound [(i1-Pr2N)BN(SiMe3)P(SiMe3)]2 (13a). The reaction of (Ph2N)B(Cl)P(SiMe3)2 (1b) with LiP(SiMe3)2 produces the only isolable bis(phosphanyl)borane (5b), while combination of (R2N)B(Cl)Ph2 with LiPH2 · DME yields new diphosphadiboretanes 6 {(R2N)BPH}2 (R2Ni1-Pr2N, Ph2N and tmp2,2,6,6-tetramethylpiperidino) and triphosphatriborinanes 7 {(R2N)BPH}3 (R2N(Me3Si)2N, Me2N and Et2N). Two salts, [(i1-Pr2N) DME]2 (8a) and [tmpLi · DME]2 (8c) (DMEethylene glycol dimethyl ether) are also isolated. The results of molecular structure determinations for [(i1-Pr2N)Bn(SiMe3)P(SiMe3)]2 (13a), [tmpBPH]2 (4c), [tmpBPH]2 · Cr(CO)5 (7c), {[(Me3Si)2N]BPH}3 (4d), {[(Me3Si)2N]BPH}3 · Cr(CO)5 (7d), (Ph2N)B[P(SiMe3)2]2 (5b), and [(i1-Pr2N) · DME]2 (8a) are discussed.

The state of the art in the Czochralski growth of various optical-quality ferroelectric tungsten bronze single crystals is reviewed with respect to crystal structure, phase transitions and cationic make-up. Based on our growth of over 25 single crystal bronzes, we have classified these bronzes into four categories having distinctly different ferroelectric and optical characteristics. With the use of this classification, optimal bronzes can be chosen for specific electro-optic and photorefractive applications.

Two-dimensional solitonic orbital waveguides as y junctions were formed in a strontium barium niobate crystal. The waveguides are 10–20 μm in diameter and propagate unpolarized light.

Cross talk is observed during the transient time of the photorefractive grating formation in a mutually pumped phase conjugator. We show that this feature can be used to transfer pictorial information from one location to another. The transfer is instantaneous and is demonstrated at a resolution of 6 lines/mm.

Syntheses for (i-Pr[sub 2]N)[sub 2]BP(SiMe[sub 3])[sub 2] and (i-Pr[sub 2]N)[sub 2]BPH[sub 2] from (i-Pr[sub 2]N)[sub 2]BCl and LiP(SiMe[sub 3])[sub 2] or LiPH[sub 2] and for ([Li [center dot] DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] from (i-Pr[sub 2]N)[sub 2]BPH[sub 2] and BuLi are described. The species ([Li[center dot]DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] is a useful synthon for diborylphosphines, and preparations of [(i-Pr[sub 2]N)[sub 2]B][sub 2]PH, Ph[sub 2]NB[P(H)B(i-Pr[sub 2]N)[sub 2]][sub 2], and [(i-Pr[sub 2]N)[sub 2]B][(R[sub 2]N)(Cl)B]PH (R[sub 2]N = i-Pr[sub 2]N, tmp, [Me[sub 3]Si][sub 2]N) are presented. Metal carbonyl coordination chemistry and selected substitution chemistry of these reagents are also described. The molecular structures of ([Li[center dot]DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] (3), [(i-Pr[sub 2]N)[sub 2]B][tmpB(Cl)]PH (7), [(i-Pr[sub 2]N)[sub 2]B][tmpB(Cl)]PH[center dot]Cr(CO)[sub 5] (13), and [(i-Pr[sub 2]N)[sub 2]B][sub 2]PH[center dot]Cr(CO)[sub 5] (12) have been determined by single crystal X-ray diffraction analyses.

Experimental observations are reported which demonstrate that the response time for beam fanning, self-pumped phase conjugation, and double phase conjugation can be shortened by more than an order of magnitude without a significant reduction in coupling strength by using a cyclindrical lens to focus incident laser light into a photorefractive crystal. These results are compared with those obtained using a spherical lens where a reduction in the photorefractive response time is accompanied by a corresponding reduction in coupling strength. It is shown that the fidelity of a phase conjugate beam is not degraded when cylindrical optics are used.

The azidoborazines [Me3N3B2(Me)2B(N3)] and [H3N3B3(N3)3] were prepared from the combination of Me3SiN3 and the chloroborazines [Me3N3B2(Me)2BCl] and (H3N3B3Cl3). The compounds have been characterized by analytical and spectroscopic methods. The molecular structure of [H3N3B3(N3)3] has been confirmed by single-crystal X-ray diffraction techniques: triclinic space group P1 with a = 8.579(1) A, b = 9.182(1) A, c = 12.043(1) A, α = 104.62(1)°, β = 90.26(1)°, γ = 110.74(1)°, and Z = 4. The thermal behavior of the azides have been examined by TGA/DTA. The explosion sensitivity of [H3N3B3(N3)3], which contains 82.58% nitrogen by weight, has been accessed by drop weight impact, spark, and friction tests. These measurements indicate that [H3N3B3(N3)3] is a relatively sensitive explosive. The Staudinger reactivity of the azides with Ph3P was examined, and [H3N3B3(N3)3] was found to produce [Ph3PNH2](N3). The molecular structure of this compound was determined by single-crystal X-ray diffraction techniques: ortho...

The reaction of (i-Pr 2 N)B(Cl)P(SiMe 3 ) 2 with (i-Pr 2 N)BCl 2 in a 2:1 ratio results in the formation of a trigonalbipyramidal compound, P 2 (i-Pr 2 NB) 3 . A more controlled, predictable synthesis of related P 2 B 3 cages is available from reactions of 1,3,2,4-diphosphadiboretanes (HPBNR 2 ) 2 with n-BuLi, followed by addition of R 2 NBCl 2 and then t-BuLi.

Syntheses for (i-Pr[sub 2]N)[sub 2]BP(SiMe[sub 3])[sub 2] and (i-Pr[sub 2]N)[sub 2]BPH[sub 2] from (i-Pr[sub 2]N)[sub 2]BCl and LiP(SiMe[sub 3])[sub 2] or LiPH[sub 2] and for ([Li [center dot] DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] from (i-Pr[sub 2]N)[sub 2]BPH[sub 2] and BuLi are described. The species ([Li[center dot]DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] is a useful synthon for diborylphosphines, and preparations of [(i-Pr[sub 2]N)[sub 2]B][sub 2]PH, Ph[sub 2]NB[P(H)B(i-Pr[sub 2]N)[sub 2]][sub 2], and [(i-Pr[sub 2]N)[sub 2]B][(R[sub 2]N)(Cl)B]PH (R[sub 2]N = i-Pr[sub 2]N, tmp, [Me[sub 3]Si][sub 2]N) are presented. Metal carbonyl coordination chemistry and selected substitution chemistry of these reagents are also described. The molecular structures of ([Li[center dot]DME][(i-Pr[sub 2]N)[sub 2]BP(H)])[sub 2] (3), [(i-Pr[sub 2]N)[sub 2]B][tmpB(Cl)]PH (7), [(i-Pr[sub 2]N)[sub 2]B][tmpB(Cl)]PH[center dot]Cr(CO)[sub 5] (13), and [(i-Pr[sub 2]N)[sub 2]B][sub 2]PH[center dot]Cr(CO)[sub 5] (12) have been determined by single crystal X-ray diffraction analyses.

The optimum performance of a photorefractive two‐beam coupling fluence limiter is presented. A two‐level, single‐dopant‐species model is used to determine the minimum transmitted fluence for different crystal dopant densities and incident fluences. The effects on limiter performance for different beam parameters such as the modulation ratio and crossing angle and for different crystal parameters such as the mobility, electro‐optic coefficient, and dielectric constant are determined.

A GaNxOy precursor powder has been prepared by reaction of an aqueous Ga(NO3)3 aerosol with NH3(g) at 1050 °C. This powder is efficiently converted to crystalline h-GaN by heat treatment under NH3 at 1050 °C.

Cross talk is observed in a photorefractive bridge mutually pumped phase conjugator during the transient time of photorefractive grating formation and is utilized to construct a moving-object correlator. The correlation of various input images has been demonstrated and compared with calculated results. The device is currently capable of a resolution of approximately 4 to 6 lines/mm.

The photorefractive effect is demonstrated in single crystals of ferroelectric Ce-doped (BaSr)6Ti2Nb8O30 for the first time to our knowledge. The maximum intensity gain, measured by two-beam coupling at a 488-nm wavelength, was Γ ~ 20 cm−1. The photorefractive time response, also measured from beam coupling, was determined to be 0.1 s at an incident intensity of I = 1 W/cm2.

The principle of incoherent-to-coherent conversion is demonstrated in several photorefractive oxide crystals using a self-pumped phase-conjugator geometry. Resolution in excess of 30 line pairs/mm has been obtained for writing beams of a few milliwatts of power. The combined read/write function for a single frame showed a time response of approximately 140 ms at an intensity of 1 W/cm2 for the crystals used in these demonstrations.

Self-pumping in cerium-doped strontium barium niobate has been observed with phase-conjugate reflectivities near 6% and a formation time of 8 sec for a 200-mW/cm(2)beam at 442 nm. The time response for asymmetrical self-defocusing was also measured, and the observed transmissions through the crystal at normal incidence were limited to about 1.5% of the incident radiation.

Submillimeter-wave laser action is reported for the first time in fully deuterated methyl fluoride. Twelve new laser lines were obtained by optical pumping with twelve CO(2) laser lines in the 9- and 10-microm regions. Milliwatt-level cw lasing was observed on two lines in an unoptimized hole-coupled waveguide resonator.

Color phase-conjugate imaging is demonstrated using a multi-colored laser beam. Speed of response, size of the image, clarity of the image, and the intensity of the image are investigated. Color images are stored and recalled without crosstalk between different colors.

A definitive demonstration of the use of a photorefractive crystal to project a three-dimensional image in space is reported on. The image is bright and different perspective views of the object appear as the viewing direction is changed.

We demonstrated mutual injection locking and coherent beam combining of three individual Nd:YVO4 laser modules. A beam splitter couples three lasers as well as combines their outputs. In the free running state, the divergence of combined beams is large. Under mutual injection locking, the divergence of the combined beams becomes substantially smaller than that in the free-running state and is as small as that of the individual laser beam. Mutual injection locking was also realized without active stabilization with large individual laser cavity length difference and low individual laser Q-factor.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Experimental data are presented, which demonstrates an optical limiter based on a large birefringence which is optically induced in bacteriorhodopsin. The induced birefringence is observed to be a function of incident intensity, but saturates at a value of about 0.454 W/cm2. A measured value of Δn of 6.6×10−4 at a wavelength of 514 nm is reported. The observed birefringence is found to be in good agreement with a proposed model.

In this paper, a comparison of ceramic Nd:YAG manufacturing techniques are presented, including an overview of the coprecipitation process and the solid state reaction process. Merits and risks of each from a commercial manufacturing viewpoint are also presented.

Laser power scaling, while preserving the diffraction-limited beam quality, is one of the most challenging problems in high power laser development. Heat removal from a thermal distortion-prone active medium is a major hurdle in power scaling. This is the more so with solid-state lasers in which, unlike the gas and liquid lasers, the active medium itself cannot be "recirculated" to facilitate a proper no-distortion heat exchange. Another significant hurdle, if merely scaling a single power oscillator is pursued, is lateral amplified spontaneous emission (ASE), which inherently limits area scaling. Phase conjugation by stimulated Brillouin scattering (SBS) is a powerful way to achieve beam quality improvement while also providing coherent beam combination due to SBS-assisted four-wave mixing. Technical parameters of fully optimized system with nearly diffraction limited output beam are being presented.

Lasers have come a long way since the first demonstration by Maiman of a ruby crystal laser in 1960. Lasers are used as scientific tools as well as for a wide variety of applications for both commercial industry and the military. Today lasers come in all types, shapes and sizes depending on their application. The solid-state laser has some distinct advantages in that it can be rugged, compact, and self contained, making it reliable over long periods of time. With the advent of diode laser pumping a ten times increase in overall laser efficiency has been realized. This significant event, and others, is changing the way solid-state lasers are applied and allows new possibilities. One of those new areas of exploration is the high energy laser. Solid-state lasers for welding are already developed and yield energies in the 0.5 to 6 kilojoule range. These lasers are at the forefront of what is possible in terms of high energy solid-state lasers. It is possible to achieve energies of greater than 100 kJ. These sorts of energies would allow applications, in addition to welding, such as directed energy weapons, extremely remote sensing, power transfer, propulsion, biological and chemical agent neutralization and unexploded and mine neutralization. This article will review these new advances in solid-state lasers and the different paths toward achieving a high energy laser. The advantages and challenges of each approach will be highlighted.

The Army has initiated a flexible display research program. This program is part of the Army's strategy to create technologies that will enable revolutionary designs and transformational weapons systems for the Objective Force. The ARL flexible display program is more general than just for the dismounted soldier-it will also have implications for air and vehicular crews, and for the other services, even though it is not a DoD tri-service program per se. “Flexible” is defined in the program as displays that operate under conditions from conformal applications, limited flexing, to rollable displays for compact storage. The Army program will include display manufacturing concepts that enable roll-to-roll processes reduce cost, to tap a strong U.S. domestic industrial strength, and, eventually, to enable fabrication of very large sizes. There is commercial interest in flexible displays for applications ranging from wearable electronics for road-warriors and gamers to large screen 71-in. 1920x1200 color pixel consumer high definition television sets for walls. Industry willingness to cost share will be a key criterion in identifying investment opportunities that are necessary and timely from among all that may be envisioned. Some anticipated military applications and a roadmap are presented that identify the technology barriers at the materials, device and manufacturing levels to the creation of flexible display technology.

A novel methodology has been developed for the investigation of bacterial spores. Specifically, this method has been used to probe the spore coat composition of several Bacillus species. This technique may be useful in many applications; most notably, development of novel detection schemes toward potentially harmful biological agents. This method would also be useful as an ancillary environmental monitoring system where sterility is of importance (i.e., food preparation areas as well as invasive and minimally invasive medical applications). This unique detection scheme is based on the near-infrared (NIR) Surface-Enhanced-Raman-Scattering (SERS) from single, optically trapped, bacterial spores. The SERS spectra of several bacterial spores in aqueous media have been measured using SERS substrates based on 60-nm diameter gold colloids bound to 3-Aminopropyltriethoxysilane derivatized glass. The light from a 785-nm laser diode was used to capture/manipulate as well as simultaneously excite the SERS of an individual bacterial spore. The collected SERS spectra were examined for uniqueness and the applicability of this technique for the species identification of bacterial spores.

We present experimental results showing an improvement in the spatial resolution of phase conjugate images obtained from mutually pumped phase conjugators. Resolutions of >100 lines/mm are presented and we demonstrate that this resolution can be achieved while performing image processing tasks such as the addition and subtraction of complex spatial distributions. These results represent greater than an order of magnitude improvement over previously reported resolutions obtained in photorefractive mutually pumped phase conjugators and approach the theoretical limit imposed by the grating spacing and crosstalk.

The effect on the photorefractive and optical properties by varying Cr and Mo dopant concentrations equally in co-doped SBN:60 is investigated. We report the effect on the absorption, two-beam coupling, speed of response, and diffraction efficiency. From these measurements the role of the donor and acceptor density is determined.

Recent results which show several ways to improve the photorefractive time response in strontium barium niobate and barium strontium potassium sodium niobate tungsten bronze crystals are presented. The techniques used were thermal, applied fields, self-generated internal fields, and focusing. Orders-of-magnitude improvements in the time response were demonstrated for beam fanning, self-pumped phase conjugation, and double phase conjugation. >

In this paper, we describe the storage and retrieval of three-dimensional (3D), true color holograms in a photorefractive crystal. The 3D image reproduces the actual colors of the object. The 3D hologram is visible over a wide perspective as demonstrated by moving one's head back and forth while viewing the hologram. The wide field-of-view of the hologram is also demonstrated using an imaging lens with a color CCD camera mounted on a goniometer to record various perspectives.

Three-dimensional holograms were recorded in a cerium-doped, strontium barium niobate (SBN:75) photorefractive crystal. These holograms are shown to not degrade after more than one week of continuous readout and to reconstruct reproductions of the original object with an observable field of view of approximately 35 degrees.

The rapid advances in full-color displays based on organic light emitting devices (OLEDS) and advances in nonemissive technologies have opened new military and commercial applications. For emissive displays, organic based devices are uniquely capable of being deposited at room temperature, which offers the possibility for fabrication on flexible substrates. Most passive technologies also have this property. In this talk, we will highlight the recent advances towards flexible emissive displays based on OLED technology and light modulating technology that are currently funded by the government. Here, we will provide an overview of the fabrication issues that include: the substrate, active and passive matrix drivers, small molecule and polymer based emissive layers, as well as sealing. The talk will provide an overview of the different approaches taken to address these issues and what are the common issues for all technologies.

The Army Research Laboratory (ARL) conducts a broad-based optoelectronics R and D program that addresses a number of Army applications. This program covers the full range of activities from basic materials development to component development and integration into higher levels of optoelectronic functionality. This paper addresses technology areas of interest to ARL including IR detection and imaging, IR sources, ladar, multifunction optoelectronic integration, diffractive optics, optoelectronic interconnects/processing, waveguide integrated optics, wide bandgap optoelectronics, and nonlinear optics. These areas represent a cross-section of the work conducted in the Sensors and Electron Deices Directorate of ARL. Space does not allow comprehensive discussion of the R and D program each of these technology thrust ares, but references are provided in each case so that the interested reader can pursue each of these topics further.

The Army Research Laboratory has had an active program in displays for many years since all Amy systems require displays of some type. Historically the program was predominately a 6.2 to 6.3 development work. Over the last few years the emphasis has been changing to more basic work. This paper discusses our current program.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An innovative technique for generating a three dimensional holographic display using strontium barium niobate (SBN) is discussed. The resultant image is a hologram that can be viewed in real time over a wide perspective or field of view (FOV). The holographic image is free from system-induced aberrations and has a uniform, high quality over the entire FOV. The enhanced image quality results from using a phase conjugate read beam generated from a second photorefractive crystal acting as a double pumped phase conjugate mirror (DPPCM). Multiple three dimensional images have been stored in the crystal via wavelength multiplexing.

We report on a definitive demonstration of a 3D holographic display utilizing a photorefractive crystal. The resultant holographic image is viewed in real-time over a wide perspective, which can be extended by a mosaic of crystals. The image is also free from system-induced aberrations and has a uniform high quality over the entire range of FOV angles. The enhanced image quality results from the use of a phase-conjugate read beam generated from a second photorefractive crystal acting as a double-pumped phase- conjugate mirror. Multiple 3D images have been stored in the crystal via wavelength and angle multiplexing.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have demonstrated that a multicolor 3D hologram with a large perspective view can be stored and reproduced using a photorefractive crystal. This display is advantageous because of its simple recording process and large storage capacity.

We have investigated the potential for using photorefractive phenomena in optical limiting devices. The major obstacle preventing the photorefractive limiter from reaching this potential has been speed of response. In this paper we report on several techniques which are successful in enhancing the photorefractive beam fanning response time. In particular, we demonstrate and characterize the use of applied electric fields, gratings to seed the beam fan, and cylindrical focusing. We also report the first demonstration of a prototype beam fanning optical limiter encompassing many of the proposed improvements.

The nonlinear transmission of Zn:Tetrabenzporphyrin was measured in a Z-scan setup using 532 nm wavelength laser light with a 13 ns pulse duration. The excited-state absorption cross section, the excited-state refractive index cross section and the linear and nonlinear absorption contribution to a thermal image index change are discussed. The effects of fluorescence and acoustic waves on the nonlinear response of TBP have been determined. Limiter performance was modeled in an f/14 limiter and saturation effects were identified.