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Sample records for crystal sapphire optical

  1. Submicron diameter single crystal sapphire optical fiber

    SciTech Connect

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers is the first step in achieving optical and sensing performance on par with its fused silica counterpart.

  2. Submicron diameter single crystal sapphire optical fiber

    DOE PAGES

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  3. Single Crystal Sapphire Optical Fiber Sensor Instrumentation

    SciTech Connect

    Anbo Wang; Russell May; Gary R. Pickrell

    2000-10-28

    The goal of this 30 month program is to develop reliable accurate temperature sensors based on single crystal sapphire materials that can withstand the temperatures and corrosive agents present within the gasifier environment. The research for this reporting period has been segregated into two parallel paths--corrosion resistance measurements for single crystal sapphire fibers and investigation of single crystal sapphire sensor configurations. The ultimate goal of this phase one segment is to design, develop and demonstrate on a laboratory scale a suitable temperature measurement device that can be field tested in phase two of the program.

  4. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    SciTech Connect

    A. Wang; G. Pickrell; R. May

    2002-09-10

    In this research program, several optical instruments for high temperature measurement based on single crystal sapphire material are introduced and tested for real-time, reliable, long-term monitoring of temperatures for coal gasifier. These are sapphire fiber extrinsic Fabry-Perot interferometric (EFPI) sensor; intensity-measurement based polarimetric sapphire sensor and broadband polarimetric differential interferometric (BPDI) sapphire sensor. Based on current evaluation and analysis of the experimental results, the broadband polarimetric differential interferometric (BPDI) sensor system was chosen for further prototype instrumentation development. This approach is based on the self-calibrating measurement of optical path differences (OPD) in a single-crystal sapphire disk, which is a function of both the temperature dependent birefringence and the temperature dependent dimensional changes. The BPDI sensor system extracts absolute temperature information by absolute measurement of phase delays. By encoding temperature information in optical spectrum instead of optical intensity, this sensor guarantees its relative immunity to optical source power fluctuations and fiber losses, thus providing a high degree of long-term measurement stability which is highly desired in industrial applications. The entire prototype for BPDI system including the single crystal sapphire probe, zirconia prism, alumina extension tube, optical components and signal processing hardware and software have shown excellent performance in the laboratory experiments shown in this report.

  5. Modal reduction in single crystal sapphire optical fiber

    NASA Astrophysics Data System (ADS)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-01

    A type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high- and low-index regions in the azimuthal direction. The structure retains a "core" region of pure single crystal (SC) sapphire in the center of the fiber and a "cladding" region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying the effective core diameter and the dimensions of the "windmill"-shaped cladding. The simulation results showed that the number of guided modes was significantly reduced in the windmill fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the windmill SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.

  6. Modal reduction in single crystal sapphire optical fiber

    SciTech Connect

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying the effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.

  7. Modal reduction in single crystal sapphire optical fiber

    DOE PAGES

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying themore » effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.« less

  8. Single-Crystal Sapphire Optical Fiber Sensor Instrumentation

    SciTech Connect

    Pickrell, Gary; Scott, Brian; Wang, Anbo; Yu, Zhihao

    2013-12-31

    This report summarizes technical progress on the program “Single-Crystal Sapphire Optical Fiber Sensor Instrumentation,” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. This project was completed in three phases, each with a separate focus. Phase I of the program, from October 1999 to April 2002, was devoted to development of sensing schema for use in high temperature, harsh environments. Different sensing designs were proposed and tested in the laboratory. Phase II of the program, from April 2002 to April 2009, focused on bringing the sensor technologies, which had already been successfully demonstrated in the laboratory, to a level where the sensors could be deployed in harsh industrial environments and eventually become commercially viable through a series of field tests. Also, a new sensing scheme was developed and tested with numerous advantages over all previous ones in Phase II. Phase III of the program, September 2009 to December 2013, focused on development of the new sensing scheme for field testing in conjunction with materials engineering of the improved sensor packaging lifetimes. In Phase I, three different sensing principles were studied: sapphire air-gap extrinsic Fabry-Perot sensors; intensity-based polarimetric sensors; and broadband polarimetric sensors. Black body radiation tests and corrosion tests were also performed in this phase. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. At the beginning of Phase II, in June 2004, the BPDI sensor was tested at the Wabash River coal gasifier

  9. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    SciTech Connect

    A. Wang; G. Pickrell; R. May

    2002-09-10

    Accurate measurement of temperature is essential for the safe and efficient operation and control of a wide range of industrial processes. Appropriate techniques and instrumentation are needed depending on the temperature measurement requirements in different industrial processes and working environments. Harsh environments are common in many industrial applications. These harsh environments may involve extreme physical conditions, such as high-temperature, high-pressure, corrosive agents, toxicity, strong electromagnetic interference, and high-energy radiation exposure. Due to these severe environmental conditions, conventional temperature sensors are often difficult to apply. This situation has opened a new but challenging opportunity for the sensor society to provide robust, high-performance, and cost-effective temperature sensors capable of operating in those harsh environments. The focus of this research program has been to develop a temperature measurement system for temperature measurements in the primary and secondary stages of slagging gasifiers. For this application the temperature measurement system must be able to withstand the extremely harsh environment posed by the high temperatures and corrosive agents present in these systems. Real-time, accurate and reliable monitoring of temperature for the coal gasification process is important to realize the full economic potential of these gasification systems. Long life and stability of operation in the high temperature environment is essential for the temperature measurement system to ensure the continuous running of the coal gasification system over the long term. In this high temperature and chemically corrosive environment, rather limited high temperature measurement techniques such as high temperature thermocouples and optical/acoustic pyrometers are available, each with their own limitations. In this research program, five different temperature sensing schemes based on the single crystal sapphire

  10. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    SciTech Connect

    A. Wang; G. Pickrell; R. May

    2002-10-18

    Accurate measurement of temperature is essential for the safe and efficient operation and control of a wide range of industrial processes. Appropriate techniques and instrumentation are needed depending on the temperature measurement requirements in different industrial processes and working environments. Harsh environments are common in many industrial applications. These harsh environments may involve extreme physical conditions, such as high-temperature, high-pressure, corrosive agents, toxicity, strong electromagnetic interference, and high-energy radiation exposure. Due to these severe environmental conditions, conventional temperature sensors are often difficult to apply. This situation has opened a new but challenging opportunity for the sensor society to provide robust, high-performance, and cost-effective temperature sensors capable of operating in those harsh environments. The focus of this research program has been to develop a temperature measurement system for temperature measurements in the primary and secondary stages of slagging gasifiers. For this application the temperature measurement system must be able to withstand the extremely harsh environment posed by the high temperatures and corrosive agents present in these systems. Real-time, accurate and reliable monitoring of temperature for the coal gasification process is important to realize the full economic potential of these gasification systems. Long life and stability of operation in the high temperature environment is essential for the temperature measurement system to ensure the continuous running of the coal gasification system over the long term. In this high temperature and chemically corrosive environment, rather limited high temperature measurement techniques such as high temperature thermocouples and optical/acoustic pyrometers are available, each with their own limitations. In this research program, five different temperature sensing schemes based on the single crystal sapphire

  11. Optical Properties of Single-Crystal Sapphire Fibers

    NASA Astrophysics Data System (ADS)

    Merberg, Glenn N.

    1992-01-01

    The optical properties of edge-defined, film-fed growth (EFG) and laser heated pedestal growth (LHPG) sapphire fibers were characterized, and the utility of these fibers for medical and industrial applications assessed. While EFG fibers are not yet produced with good optical quality, they offer enormous potential for mass production of sapphire fibers. The LHPG process has been successfully employed to produce good optical quality sapphire. This dissertation focussed on the optical attenuation mechanisms which limit the transmission properties of both EFG and LHPG sapphire fibers. The EFG fibers obtained for this research were found to contain bubbles along the fiber axes. As a result of the bubble inclusions, the measured optical scattering coefficients of the fibers were quite high. At a wavelength of 2.94 mum, a typical 280 μm diameter EFG fiber had a total attenuation coefficient of 18 dB/m. The contribution of scattering to this loss was measured as 17 dB/m, and the absorptive component as measured by laser calorimetry was 1 dB/m. The wavelength dependence of the scattering in EFG fibers was found to be lambda^{-1.5}, which is consistent with a Mie scattering model for scattering of light by bubbles on the dimensional order of the wavelength. Some of the LHPG fibers grown at Rutgers had measured attenuation coefficients of less than 2 dB/m at 2.94 μm wavelength. The absorptive component of this loss was measured by laser calorimetry as 0.7 dB/m, while the scattering loss was 1 dB/m. Optical scattering in Rutgers LHPG fibers had a lambda^ {-4} wavelength dependence, although the scattering coefficients were considerably higher than predicted for intrinsic scattering. Although visible absorbing color -centers were discovered in Rutgers LHPG fibers, excessive optical scattering dominated the attenuation in this spectral region. Melt extruded Teflon-FEP claddings were applied to LHPG fibers. The claddings were very effective in reducing evanescent coupling of Er

  12. Sapphire shaped crystals for medicine

    NASA Astrophysics Data System (ADS)

    Shikunova, A.; Kurlov, V. N.

    2016-01-01

    The favorable combination of excellent optical and mechanical properties of sapphire makes it an attractive structural material for medicine. We have developed a new kind of medical instruments and devices for laser photodynamic and thermal therapy, laser surgery, fluorescent diagnostics, and cryosurgery based on sapphire crystals of various shapes with capillary channels in their volume.

  13. Light refraction in sapphire plates with a variable angle of crystal optical axis to the surface

    SciTech Connect

    Vetrov, V. N. Ignatenkov, B. A.

    2013-05-15

    The modification of sapphire by inhomogeneous plastic deformation makes it possible to obtain plates with a variable angle of inclination of the crystal optical axis to the plate surface. The refraction of light in this plate at perpendicular and oblique incidence of a parallel beam of rays is considered. The algorithm of calculating the refractive index of extraordinary ray and the birefringence is proposed.

  14. Design and analysis of large-core single-mode windmill single crystal sapphire optical fiber

    NASA Astrophysics Data System (ADS)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2016-06-01

    We present a large-core single-mode "windmill" single crystal sapphire optical fiber (SCSF) design, which exhibits single-mode operation by stripping off the higher-order modes (HOMs) while maintaining the fundamental mode. The "windmill" SCSF design was analyzed using the finite element analysis method, in which all the HOMs are leaky. The numerical simulation results show single-mode operation in the spectral range from 0.4 to 2 μm in the windmill SCSF, with an effective core diameter as large as 14 μm. Such fiber is expected to improve the performance of many of the current sapphire fiber optic sensor structures.

  15. Single-crystal sapphire tubes as economical probes for optical pyrometry in harsh environments

    SciTech Connect

    Ruzicka, Jakub; Houzvicka, Jindrich; Bok, Jiri; Praus, Petr; Mojzes, Peter

    2011-12-20

    One-end-sealed single-crystal sapphire tubes are presented as a simple, robust, and economical alternative for bulky lightpipe probes. Thermal radiation from a blackbody cavity created at the inner surface of the sealed end is gathered by a simple lens-based collecting system and transmitted via optical fiber to the remote detection unit. Simplicity and applicability of the concept are demonstrated by the combination of commercially available sapphire tubes with a common optical pyrometer. Radiation thermometers with sapphire tubes as invasive probes can be useful for applications requiring immunity to electromagnetic interference, resistance to harsh environments, simple replacement in the case of failure, and enhanced mechanical firmness, enabling wider range probe positioning inside the medium of interest.

  16. Single-crystal sapphire tubes as economical probes for optical pyrometry in harsh environments.

    PubMed

    Růžička, Jakub; Houžvička, Jindřich; Bok, Jiří; Praus, Petr; Mojzeš, Peter

    2011-12-20

    One-end-sealed single-crystal sapphire tubes are presented as a simple, robust, and economical alternative for bulky lightpipe probes. Thermal radiation from a blackbody cavity created at the inner surface of the sealed end is gathered by a simple lens-based collecting system and transmitted via optical fiber to the remote detection unit. Simplicity and applicability of the concept are demonstrated by the combination of commercially available sapphire tubes with a common optical pyrometer. Radiation thermometers with sapphire tubes as invasive probes can be useful for applications requiring immunity to electromagnetic interference, resistance to harsh environments, simple replacement in the case of failure, and enhanced mechanical firmness, enabling wider range probe positioning inside the medium of interest.

  17. Single-crystal sapphire tubes as economical probes for optical pyrometry in harsh environments.

    PubMed

    Růžička, Jakub; Houžvička, Jindřich; Bok, Jiří; Praus, Petr; Mojzeš, Peter

    2011-12-20

    One-end-sealed single-crystal sapphire tubes are presented as a simple, robust, and economical alternative for bulky lightpipe probes. Thermal radiation from a blackbody cavity created at the inner surface of the sealed end is gathered by a simple lens-based collecting system and transmitted via optical fiber to the remote detection unit. Simplicity and applicability of the concept are demonstrated by the combination of commercially available sapphire tubes with a common optical pyrometer. Radiation thermometers with sapphire tubes as invasive probes can be useful for applications requiring immunity to electromagnetic interference, resistance to harsh environments, simple replacement in the case of failure, and enhanced mechanical firmness, enabling wider range probe positioning inside the medium of interest. PMID:22193189

  18. Design and analysis of large-core single-mode windmill single crystal sapphire optical fiber

    DOE PAGES

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2016-06-01

    We present a large-core single-mode “windmill” single crystal sapphire optical fiber (SCSF) design, which exhibits single-mode operation by stripping off the higher-order modes (HOMs) while maintaining the fundamental mode. The “windmill” SCSF design was analyzed using the finite element analysis method, in which all the HOMs are leaky. The numerical simulation results show single-mode operation in the spectral range from 0.4 to 2 μm in the windmill SCSF, with an effective core diameter as large as 14 μm. Such fiber is expected to improve the performance of many of the current sapphire fiber optic sensor structures.

  19. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-04-01

    This report summarizes technical progress over the first six months of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on analyzing and testing factors that impact performance degradation of the initially designed sensor prototype, including sensing element movement within the sensing probe and optical signal quality degradation. Based these results, a new version of the sensing system was designed by combining the sapphire disk sensing element and the single crystal zirconia right angle light reflector into one novel single crystal sapphire right angle prism. The new sensor prototype was tested up to 1650 C.

  20. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-11-01

    This report summarizes technical progress over the second six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on evaluating corrosion effects in single crystal sapphire at temperatures up to 1400 C, and designing the sensor mechanical packaging with input from Wabash River Power Plant. Upcoming meetings will establish details for the gasifier field test.

  1. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Anbo Wang

    2007-03-31

    This report summarizes technical progress October 2006 - March 2007 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. During the second phase, an alternative high temperature sensing system based on Fabry-Perot interferometry was developed that offers a number of advantages over the BPDI solution. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. The sapphire wafer-based interferometric sensing system that was installed at TECO's Polk Power Station remained in operation for seven months. Our efforts have been focused on monitoring and analyzing the real-time data collected, and preparing for a second field test.

  2. Thermal debracketing of single crystal sapphire brackets.

    PubMed

    Rueggeberg, F A; Lockwood, P E

    1992-01-01

    Because of their optical clarity, single crystal sapphire brackets provide an esthetic advantage over many other types of orthodontic brackets. However, debonding of these brackets has caused iatrogenic damage to enamel. Thermal debonding has been proposed for use in removing sapphire brackets without causing damage to teeth. This study determined the temperature required at the enamel/resin interface to thermally debond sapphire brackets from etched bovine enamel using 23 different commercially available orthodontic resins and one experimental product. The results indicate a wide range of debonding temperatures for the various resins. As a group, the powder-liquid materials had a statistically lower debonding temperature than the two-paste, the no-mix products, or the light-cured materials, for which the temperatures were all similar. This paper presents relative information a clinician can use in selecting an orthodontic bonding resin to minimize thermal damage to the teeth while debonding sapphire brackets.

  3. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang; Yizheng Zhu

    2005-04-01

    This report summarizes technical progress October 2004-March 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report.

  4. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2005-11-01

    This report summarizes technical progress April-September 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report. The sensing system will be installed and tested at TECO's Polk Power Station. Following a site visit in June 2005, our efforts have been focused on preparing for that field test, including he design of the sensor mechanical packaging, sensor electronics, the data transfer module, and the necessary software codes to accommodate this application.. We are currently ready to start sensor fabrication.

  5. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang

    2004-04-01

    This report summarizes technical progress over the third six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on sensor probe design and machining, sensor electronics design, software algorithm design, sensor field installation procedures, and sensor remote data access and control. Field testing will begin in the next several weeks.

  6. Failure mechanism of single crystal alumina (sapphire) in conventional machining

    SciTech Connect

    Liang, H.

    1995-12-31

    This work is to investigate the types of common failure of sapphire during machining. The various features of failure indicated and types of failure characteristics will be discussed, and where appropriate, several of the fundamental mechanisms involved will be explained. The objective of this work is to show how sapphire is removed during machining. Based on a good understanding of the failure mechanism, the machining conditions can be optimized. Machining methods discussed in this work are all conventional methods. They include grinding, diamond saw cutting, diamond core drilling, abrasive and chemomechanical polishing. The machining conditions used for each different orientation of crystal planes were consistent. The machining surfaces were observed by using optical microscope and scanning electron microscope. The surface roughness and subsurface damage were also measured and compared. Under a consistent machining condition, sapphire is machined based on its different crystal orientations. Before machining, these crystals were annealed in order to get rid of the preexisting defects. After machining, these samples were etched, and observed under optical and scanning electronic microscope. A series of observations was compared. The machining induced failures, as observed, for example, are cleavage, twinning, chipping, and pitting, etc. The effect of crystal orientation on machining is also discussed. Results show the effect of crystal orientation on material removal rate, surface and subsurface damage and thereafter surface finish. It suggests a certain orientation of crystal for a certain type of machining method.

  7. Advances in sapphire optical fiber sensors

    NASA Technical Reports Server (NTRS)

    Wang, Anbo; Wang, George Z.; Gollapudi, Sridhar; May, Russell G.; Murphy, Kent A.; Claus, Richard O.

    1993-01-01

    We describe the development and testing of two sapphire fiber sensor designs intended for use in high temperature environments. The first is a birefringence-balanced polarimetric sapphire fiber sensor. In this sensor, two single crystal sapphire rods, acting as the birefringence sensing element, are connected to each other in such a way that the slow axis of the first rod is aligned along with the fast axis of the second rod, and the fast axis of the first rod is along the slow axis of the second rod. This sensor has been demonstrated for measurement of temperature up to 1500 C. The second is a sapphire-fiber-based intrinsic interferometric sensor. In this sensor, a length of uncoated, unclad, structural-graded multimode sapphire fiber is fusion spliced to a singlemode silica fiber to form a Fabry-Perot cavity. The reflections from the silica-to-sapphire fiber splice and the free endface of the sapphire fiber give rise to the interfering fringe output. This sensor has been demonstrated for the measurement of temperature above 1510 C, and a resolution of 0.1 C has been obtained.

  8. Anisotropy of sapphire single crystal sputtering

    SciTech Connect

    Minnebaev, K. F.; Tolpin, K. A.; Yurasova, V. E.

    2015-08-15

    We have studied the spatial distribution of particles sputtered from the base (0001) plane of a sapphire single crystal with trigonal crystalline lattice (α-Al{sub 2}O{sub 3}) that can be considered a superposition of two hexagonal close packed (hcp) structures–the ideal sublattice of oxygen and a somewhat deformed sublattice of aluminum. It is established that the particles sputtered from the base plane of sapphire are predominantly deposited along the sides of an irregular hexagon with spots at its vertices. The patterns of spots have been also studied for sputtering of particles from the (0001) face of a zinc single crystal with the hcp lattice. The spots of sputtered Zn atoms are arranged at the vertices of concentric equilateral hexagons. In both cases, the observed anisotropy of sputtering is related to focused collisions (direct and assisted focusing) and the channeling process. The chemical composition of spots has been determined in various regions of sputtered sapphire deposition. The results are discussed in comparison to analogous earlier data for secondary ion emission from an α-Al{sub 2}O{sub 3} single crystal.

  9. Sapphire Fiber Optics Sensors for Engine Test Instrumentation

    SciTech Connect

    Janney, MA

    2003-09-19

    This document is the final report for the Cooperative Research and Development Agreement (CRADA) between UT-Battelle and Prime Photonics, Inc. The purpose of this CRADA was to improve the properties of single crystal sapphire optical fibers for sensor applications. A reactive coating process was developed to form a magnesium aluminate spinel cladding on sapphire optical fibers. The resulting clad fiber had a numerical aperture, NA, of 0.09 as compared with 0.83 for the unclad fiber, dramatically enhancing its usefulness for sensor applications. Because the process allows one to control the diameter of the sapphire core within the fiber, it may be possible using this technology to develop waveguides that approach single-mode transmission character.

  10. Modern trends in crystal growth and new applications of sapphire

    NASA Astrophysics Data System (ADS)

    Akselrod, Mark S.; Bruni, Frank J.

    2012-12-01

    We provide an overview of the latest market trends and modern competing methods of sapphire crystal growth and the application of sapphire wafers as LED substrates. Almost all methods of high temperature growth from the melt are suitable for sapphire production, but each of these methods has its advantages and disadvantages depending on the application and required finished product form factor. Special attention is paid to the review of defects and imperfections that allow the engineering of new active devices based on sapphire.

  11. Optical Extinction of Sapphire Shock Loaded to 250-260 GPa

    SciTech Connect

    Hare, D E; Webb, D J; Lee, S H; Holmes, N

    2001-08-21

    Sapphire, a common optical window material used in shock-compression studies, displays significant shock-induced optical emission and extinction. It is desirable to quantify such non-ideal window behavior to enhance the usefulness of sapphire in optical studies of opaque shock-compressed samples, such as metals. At the highest stresses we can achieve with a two-stage gas gun it is technically very difficult to study the optical properties of sapphire without the aid of some opaque backing material, hence one is invariably compelled to deconvolve the optical effects of the opaque surface and the sapphire. In an effort to optimize this deconvolution process, we have constructed sapphire/thin-film/sapphire samples using two basic types of thin films: one optimized to emit copious optical radiation (the hot-film sample), the other designed to yield minimal emission (the cold-film sample). This sample geometry makes it easy to maintain the same steady shock-stress in the sapphire window (255 GPa in our case) while varying the window/film interface temperature. A six-channel time-resolved optical pyrometer is used to measure the emission from the sample assemblies. Two different sapphire crystal orientations were evaluated. We also comment on finite thermal conductivity effects of the thin-film geometry on the interpretation of our data.

  12. Study of the crystal structure of silicon nanoislands on sapphire

    SciTech Connect

    Krivulin, N. O. Pirogov, A. V.; Pavlov, D. A.; Bobrov, A. I.

    2015-02-15

    The results of studies of the crystal structure of silicon nanoislands on sapphire are reported. It is shown that the principal defects in silicon nanoislands on sapphire are twinning defects. As a result of the formation of such defects, different crystallographic orientations are formed in silicon nanoislands on sapphire. In the initial stages of the molecular-beam epitaxy of silicon on sapphire, there are two basic orientations: the (001) orientation parallel to the surface and the (001) orientation at an angle of 70° to the surface.

  13. Removal of Lattice Imperfections that Impact the Optical Quality of Ti:Sapphire using Advanced Magnetorheological Finishing Techniques

    SciTech Connect

    Menapace, J A; Schaffers, K I; Bayramian, A J; Davis, P J; Ebbers, C A; Wolfe, J E; Caird, J A; Barty, C J

    2008-02-26

    Advanced magnetorheological finishing (MRF) techniques have been applied to Ti:sapphire crystals to compensate for sub-millimeter lattice distortions that occur during the crystal growing process. Precise optical corrections are made by imprinting topographical structure onto the crystal surfaces to cancel out the effects of the lattice distortion in the transmitted wavefront. This novel technique significantly improves the optical quality for crystals of this type and sets the stage for increasing the availability of high-quality large-aperture sapphire and Ti:sapphire optics in critical applications.

  14. Reactive ion etching of high optical quality GaN/sapphire photonic crystal slab using CH{sub 4}-H{sub 2} chemistry

    SciTech Connect

    Bouchoule, S.; Boubanga-Tombet, S.; Le Gratiet, L.; Le Vassor d'Yerville, M.; Torres, J.; Chen, Y.; Coquillat, D.

    2007-02-15

    Reactive ion etching (RIE) using a CH{sub 4}-H{sub 2} plasma is investigated for the fabrication of a GaN one-dimensional (1D) photonic crystal (PhC) slab. The dominant control parameter for the etch rate and the sidewall profile is the dc bias. The influence of operating pressure, CH{sub 4}/H{sub 2} ratio, and total gas flow rate on the etching characteristics is also presented. An etch rate as high as 85 nm/min and an overcut angle as low as 5 degree sign obtained in this work are among the best values reported for conventional RIE technique. The CH{sub 4}-H{sub 2} process is used to etch 1D PhCs with a lattice parameter ranging from 700 to 350 nm and an air filling factor of 0.30 into a 600-nm-thick GaN/sapphire slab. Sharp peaks corresponding to the resonant modes of the nanopatterned structures are observed in the experimental reflection spectra for all the lattice periods. Furthermore, the good optical quality of the nanostructures is evidenced by a resonantly enhanced second-harmonic generation experiment around 400 nm. A second-harmonic generation enhancement factor as high as 10{sup 5} is obtained, compared with the unpatterned GaN reference slab. These results demonstrate that the CH{sub 4}-H{sub 2} conventional RIE technique is well adapted to the etching of GaN PhC for the fabrication of next generation photonic devices exploiting nonlinear processes.

  15. Reduced cost and improved figure of sapphire optical components

    NASA Astrophysics Data System (ADS)

    Walters, Mark; Bartlett, Kevin; Brophy, Matthew R.; DeGroote Nelson, Jessica; Medicus, Kate

    2015-10-01

    Sapphire presents many challenges to optical manufacturers due to its high hardness and anisotropic properties. Long lead times and high prices are the typical result of such challenges. The cost of even a simple 'grind and shine' process can be prohibitive. The high precision surfaces required by optical sensor applications further exacerbate the challenge of processing sapphire thereby increasing cost further. Optimax has demonstrated a production process for such windows that delivers over 50% time reduction as compared to traditional manufacturing processes for sapphire, while producing windows with less than 1/5 wave rms figure error. Optimax's sapphire production process achieves significant improvement in cost by implementation of a controlled grinding process to present the best possible surface to the polishing equipment. Following the grinding process is a polishing process taking advantage of chemical interactions between slurry and substrate to deliver excellent removal rates and surface finish. Through experiments, the mechanics of the polishing process were also optimized to produce excellent optical figure. In addition to reducing the cost of producing large sapphire sensor windows, the grinding and polishing technology Optimax has developed aids in producing spherical sapphire components to better figure quality. In addition to reducing the cost of producing large sapphire sensor windows, the grinding and polishing technology Optimax has developed aids in producing spherical sapphire components to better figure quality. Through specially developed polishing slurries, the peak-to-valley figure error of spherical sapphire parts is reduced by over 80%.

  16. A peek into the history of sapphire crystal growth

    NASA Astrophysics Data System (ADS)

    Harris, Daniel C.

    2003-09-01

    After the chemical compositions of sapphire and ruby were unraveled in the middle of the 19th century, chemists set out to grow artificial crystals of these valuable gemstones. In 1885 a dealer in Geneva began to sell ruby that is now believed to have been created by flame fusion. Gemnologists rapidly concluded that the stones were artificial, but the Geneva ruby stimulated A. V. L. Verneuil in Paris to develop a flame fusion process to produce higher quality ruby and sapphire. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, even though Verneuil did not publicly announce his work until 1902 and did not publish details until 1904. The Verneuil process was used with little alteration for the next 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire by the Verneuil process. In the U.S., under government contract, Linde Air Products Co. implemented the Verneuil process for ruby and sapphire when European sources were cut off during World War II. These materials were essential to the war effort for jewel bearings in precision instruments. In the 1960s and 1970s, the Czochralski process was implemented by Linde and its successor, Union Carbide, to make higher crystal quality material for ruby lasers. Stimulated by a government contract for structural fibers in 1966, H. LaBelle invented edge-defined film-fed growth (EFG). The Saphikon company, which is currently owned by Saint-Gobain, evolved from this effort. Independently and simultaneously, Stepanov developed edge-defined film-fed growth in the Soviet Union. In 1967 F. Schmid and D. Viechnicki at the Army Materials Research Lab grew sapphire by the heat exchanger method (HEM). Schmid went on to establish Crystal Systems, Inc. around this technology. Rotem Industries, founded in Israel in 1969, perfected the growth of sapphire hemispheres and near-net-shape domes by gradient solidification. In the U.S., growth of near

  17. On-Orbit Results for Canada's Sapphire Optical Payload

    NASA Astrophysics Data System (ADS)

    Scott, A.; Hackett, J.

    2013-09-01

    Sapphire is the first Space Situational Awareness (SSA) satellite mission flown by Canada's Department of National Defence (DND). On February 25, 2013 Sapphire was successfully launched into a sun synchronous orbit at ~786 km altitude. The commissioning phase was a success and the Sapphire system is entering its operational phase. Canada and the United States signed an SSA Memorandum of Understanding on May 4, 2012. Under the agreement, data from DND's Sapphire satellite will be contributed to the U.S. Space Surveillance Network (SSN), enhancing the ability of both countries to detect and avoid the collision of critical space platforms with orbital debris. The Sapphire system is now collecting SSA data that will be shared with the SSN. This SSA partnership will strengthen the long standing defence relationship between the US and Canada and provide diversity in space based sensors at a time of fiscal constraint. The Sapphire satellite optical imaging payload was designed and built by COM DEV based around a small (13.25 cm) Three Mirror Anastigmat (TMA) telescope similar in design to the Space Based Visible sensor on the US Mid-Course Space Experiment satellite. The paper provides an overview of the design and operational performance of the Sapphire instrument, comparing the actual performance to the requirements. Based on lessons learned on this program we discuss potential improvements that would be feasible in a second generation Sapphire payload including the potential for using this sensor as a hosted payload in other applications.

  18. Thermal and optical behavior of sapphire fiber tips for laser angioplasty

    NASA Astrophysics Data System (ADS)

    Ashley, Simon; Brooks, Stephen G.; Gehani, Abdurrazak A.; Kester, Ralph C.; Rees, Michael R.

    1990-07-01

    Atraumatic rounded contact probes made from artificial sapphire crystal were developed for general laser surgery and are currently being evaluated for use in percutaneous laser angioplasty utilising continuous wave (cw) Nd-YAG energy (1064nm). The thermal and optical characteristics of five different types of rounded sapphire probe [Surgical Laser Technologies (SLT) - SMTR (1.8mm), MTh (2.2mm), MTRL (3.0mm); Living Technology - LT (2.2mm), OS (2.2mm)] were investigated and related to efficiency of contact ablation of arterial wall in vitro. The sapphire probes were mounted on catheters containing a 0.6 mm quartz optical fiber, coupled to a cw Nd-YAG laser. All probes produced a similar beam profile but there was some variation in their forward transmission of energy (54-85%).Probe heating occurs due to energy absorption within the sapphire and was measured in air by infrared thermography. There was a high temperature gradient from the front surface of the sapphires to the probe rim. But, at energy settings used clinically (10 J pulses, 10 Watts for 1 second) the SMTR, MTR, and MTRL probes exhibited a higher mean temperature rise (63-74 C) than the OS and LT probes (20 C) [3-way ANOVA psapphire temperature rise recorded after 5 seconds exposure at 20 Watts was 340 C, but at all energy settings sapphire temperatures were much lower than attained by metal probes. Furthermore, there was relatively little heating of the metal jacket behind the sapphires (maximum 35 C) reducing the risk of thermal injury to surrounding vessel. These properties enhanced contact ablation by the MTR probe relative to the other 2.2mm probes when applied with a downward force of 80 g, perpendicular to fresh porcine aortic segments immersed in whole blood. Penetration efficiencies at energy levels producing the most efficient ablation by each probe were as follows [mean (SD) microns/JI:- MTR 50 (7), LT 9 (5), 05 4 (2), (p

  19. Optical Crystals

    ERIC Educational Resources Information Center

    Bergsten, Ronald

    1974-01-01

    Discusses the production and structure of a sequence of optical crystals which can serve as one-, two-, and three-dimensional diffraction plates to illustrate diffraction patterns by using light rather than x-rays or particles. Applications to qualitative presentations of Laue theory at the secondary and college levels are recommended. (CC)

  20. Synthesis and Transfer of Large-Area Monolayer WS2 Crystals: Moving Toward the Recyclable Use of Sapphire Substrates.

    PubMed

    Xu, Zai-Quan; Zhang, Yupeng; Lin, Shenghuang; Zheng, Changxi; Zhong, Yu Lin; Xia, Xue; Li, Zhipeng; Sophia, Ponraj Joice; Fuhrer, Michael S; Cheng, Yi-Bing; Bao, Qiaoliang

    2015-06-23

    Two-dimensional layered transition metal dichalcogenides (TMDs) show intriguing potential for optoelectronic devices due to their exotic electronic and optical properties. Only a few efforts have been dedicated to large-area growth of TMDs. Practical applications will require improving the efficiency and reducing the cost of production, through (1) new growth methods to produce large size TMD monolayer with less-stringent conditions, and (2) nondestructive transfer techniques that enable multiple reuse of growth substrate. In this work, we report to employ atmospheric pressure chemical vapor deposition (APCVD) for the synthesis of large size (>100 μm) single crystals of atomically thin tungsten disulfide (WS2), a member of TMD family, on sapphire substrate. More importantly, we demonstrate a polystyrene (PS) mediated delamination process via capillary force in water which reduces the etching time in base solution and imposes only minor damage to the sapphire substrate. The transferred WS2 flakes are of excellent continuity and exhibit comparable electron mobility after several growth cycles on the reused sapphire substrate. Interestingly, the photoluminescence emission from WS2 grown on the recycled sapphire is much higher than that on fresh sapphire, possibly due to p-type doping of monolayer WS2 flakes by a thin layer of water intercalated at the atomic steps of the recycled sapphire substrate. The growth and transfer techniques described here are expected to be applicable to other atomically thin TMD materials.

  1. Synthesis and Transfer of Large-Area Monolayer WS2 Crystals: Moving Toward the Recyclable Use of Sapphire Substrates.

    PubMed

    Xu, Zai-Quan; Zhang, Yupeng; Lin, Shenghuang; Zheng, Changxi; Zhong, Yu Lin; Xia, Xue; Li, Zhipeng; Sophia, Ponraj Joice; Fuhrer, Michael S; Cheng, Yi-Bing; Bao, Qiaoliang

    2015-06-23

    Two-dimensional layered transition metal dichalcogenides (TMDs) show intriguing potential for optoelectronic devices due to their exotic electronic and optical properties. Only a few efforts have been dedicated to large-area growth of TMDs. Practical applications will require improving the efficiency and reducing the cost of production, through (1) new growth methods to produce large size TMD monolayer with less-stringent conditions, and (2) nondestructive transfer techniques that enable multiple reuse of growth substrate. In this work, we report to employ atmospheric pressure chemical vapor deposition (APCVD) for the synthesis of large size (>100 μm) single crystals of atomically thin tungsten disulfide (WS2), a member of TMD family, on sapphire substrate. More importantly, we demonstrate a polystyrene (PS) mediated delamination process via capillary force in water which reduces the etching time in base solution and imposes only minor damage to the sapphire substrate. The transferred WS2 flakes are of excellent continuity and exhibit comparable electron mobility after several growth cycles on the reused sapphire substrate. Interestingly, the photoluminescence emission from WS2 grown on the recycled sapphire is much higher than that on fresh sapphire, possibly due to p-type doping of monolayer WS2 flakes by a thin layer of water intercalated at the atomic steps of the recycled sapphire substrate. The growth and transfer techniques described here are expected to be applicable to other atomically thin TMD materials. PMID:25961515

  2. DOE SAPPHIRE PROJECT

    SciTech Connect

    Dr. Gary R. Pickrell

    2000-03-01

    Since this is the first report for this project an extensive background section follows on the theory of operation of the single crystal sapphire sensor technology which will be developed and field tested at the Wabash River Coal Gasification Facility. Requirements for the temperature sensors for implementation in the coal gasifiers has been established in conjunction with the industrial partner, Dynegy. Coal slag immersion tests indicate good corrosion resistance of the single crystal sapphire. However, a more sophisticated corrosion apparatus has been constructed in order to test the optical attenuation of a single crystal sapphire fiber immersed in the coal slag at high temperature. These results will be reported in the next period. The data to date for sapphire sensor development is promising. More extensive data on the sapphire fiber sensor development will be reported for the next period.

  3. Numerical computation of sapphire crystal growth using heat exchanger method

    NASA Astrophysics Data System (ADS)

    Lu, Chung-Wei; Chen, Jyh-Chen

    2001-05-01

    The finite element software FIDAP is employed to study the temperature and velocity distribution and the interface shape during a large sapphire crystal growth process using a heat exchanger method (HEM). In the present study, the energy input to the crucible by the radiation and convection inside the furnace and the energy output through the heat exchanger is modeled by the convection boundary conditions. The effects of the various growth parameters are studied. It is found that the contact angle is obtuse before the solid-melt interface touches the sidewall of the crucible. Therefore, hot spots always appear in this process. The maximum convexity decreases significantly when the cooling-zone radius (RC) increases. The maximum convexity also decreases significantly as the combined convection coefficient inside the furnace (hI) decreases.

  4. Single-crystal sapphire microstructure for high-resolution synchrotron X-ray monochromators

    DOE PAGES

    Asadchikov, Victor E.; Butashin, Andrey V.; Buzmakov, Alexey V.; Deryabin, Alexander N.; Kanevsky, Vladimir M.; Prokhorov, Igor A.; Roshchin, Boris S.; Volkov, Yuri O.; Zolotov, Dennis A.; Jafari, Atefeh; et al

    2016-03-22

    We report on the growth and characterization of several sapphire single crystals for the purpose of x-ray optics applications. Structural defects were studied by means of laboratory double-crystal X-ray diffractometry and white beam synchrotron-radiation topography. The investigations confirmed that the main defect types are dislocations. The best quality crystal was grown using the Kyropoulos technique with a dislocation density of 102-103 cm-2 and a small area with approximately 2*2 mm2 did not show dislocation contrast in many reflections and has suitable quality for application as a backscattering monochromator. As a result, a clear correlation between growth rate and dislocation densitymore » is observed, though growth rate is not the only parameter impacting the quality.« less

  5. Clinical evaluation of a single crystal sapphire tooth implant in human beings.

    PubMed

    Sclaroff, A; el-Mofty, S; Guyer, S E

    1990-08-01

    Single crystal sapphire implants are commercially prepared ceramics of aluminum oxide. These endosseous implants have been placed in patients at Washington University since 1978. The course of patients has been followed closely with periodic clinical and radiographic evaluations. Sapphire is well tolerated by hard and soft tissue and provides excellent abutments for fixed partial dentures.

  6. Effect of Charging Electron Exposure on 1064nm Transmission through Bare Sapphire Optics and SiO2 over HfO2 AR-coated Sapphire Optics

    NASA Technical Reports Server (NTRS)

    Ottens, Brian P.; Connelly, Joseph; Brown, Stephen; Roeder, james; Kauder, Lonny; Cavanaugh, John

    2008-01-01

    Experiments measuring the effect of electron exposure on 1064nm transmission for optical sapphire were conducted. Detailed before and after inspections did not identify any resulting Litchenburg patterns. Pre- and post-exposure 1064nm transmission measurements are compared.

  7. Effect of Charging Electron Exposure on 1064nm Transmission Through Bare Sapphire Optics and SiO2 over HfO2 AR-Coated Sapphire Optics

    NASA Technical Reports Server (NTRS)

    Ottens, Brian P.; Connelly, Joseph; Brown, Stephen; Roeder, James; Kauder, Lonny; Cavanaugh, John

    2010-01-01

    Experiments measuring the effect of electron exposure on 1064nm transmission for optical sapphire were conducted. Detailed before and after inspections did not identify any resulting Litchenburg patterns. Pre- and post-exposure 1064nm transmission measurements are compared.

  8. Defect Analysis of Boron Phosphide Thin Films and Sapphire Single Crystal Using Synchrotron X-ray Topography

    NASA Astrophysics Data System (ADS)

    Ding, Zihao

    Boron phosphide is an ideal semiconductor material used for neutron detectors because of its superior material properties, such as wide band gap and large thermal neutron capture cross-section of 10B. Since bulk BP is not readily available for neutron detector application, BP thin films are mainly synthesized by chemical vapor deposition (CVD). Among all the feasible substrates for BP deposition, SiC stands out due to its small lattice mismatch (4.5%) with BP, however it is necessary to optimize the growth condition to synthesize high quality BP thin films on SiC. In chapter III, BP thin film samples deposited on 4H-SiC and 6H-SiC under different growth conditions are characterized, mainly using synchrotron X-ray topography and other techniques such as optical microscopy and scanning electron microscopy. The relationship between BP thin film crystal quality and substrate material and orientation and other growth conditions is investigated. It can be concluded from the experimental data that the crystal quality of BP thin films on 4H-SiC substrate is much better than that on 6H-SiC substrate. Besides, poor crystalline quality of substrate will likely degrade the crystalline quality of epitaxial thin films. Sapphire single crystal has been widely used in high-technology industry because of its excellent combination between optical, electrical and mechanical properties. In this thesis, a-plane sapphire ribbon grown by Edge-defined Film-fed Growth method (EFG) is analyzed by characterizing the seed crystals used and the quality of as-grown ribbon, by reflection X-ray topography. Distributions and formation mechanisms of defects inside both the sapphire seed crystal and ribbon crystal are studied. Transmission topographs reveal the presence of two sets of slip bands that are nucleated from either edge, the distribution of which is symmetric in the used seed crystal and asymmetric in the pristine seed crystal. This phenomenon could be caused by the unstable growth

  9. Removal of Lattice Imperfections that Impact the Optical Quality of Ti:Sapphire using Advanced Magnetorheological Finishing Techniques

    SciTech Connect

    Menapace, J A; Schaffers, K I; Bayramian, A J; Davis, P J; Ebbers, C A; Wolfe, J E; Caird, J A; Barty, C J; Joyce, D B; Schmid, K; Schmid, F

    2007-10-09

    Ti:sapphire has become the premier lasing medium material for use in solid-state femtosecond high-peak power laser systems because of its wide wavelength tuning range. With a tuneable range from 680 to 1100 nm, peaking at 800 nm, Ti:sapphire lasing crystals can easily be tuned to the required pump wavelength and provide very high pump brightness due to their good beam quality and high output power of typically several watts. Femtosecond lasers are used for precision cutting and machining of materials ranging from steel to tooth enamel to delicate heart tissue and high explosives. These ultra-short pulses are too brief to transfer heat or shock to the material being cut, which means that cutting, drilling, and machining occur with virtually no damage to surrounding material. Furthermore, these lasers can cut with high precision, making hairline cuts of less than 100 microns in thick materials along a computer-generated path. Extension of laser output to higher energies is limited by the size of the amplification medium. Yields of high quality large diameter crystals have been constrained by lattice distortions that may appear in the boule limiting the usable area from which high quality optics can be harvested. Lattice distortions affect the transmitted wavefront of these optics which ultimately limits the high-end power output and efficiency of the laser system, particularly when operated in multi-pass mode. To make matters even more complicated, Ti:sapphire is extremely hard (Mohs hardness of 9 with diamond being 10) which makes it extremely difficult to accurately polish using conventional methods without subsurface damage or significant wavefront error. In this presentation, we demonstrate for the first time that Magnetorheological finishing (MRF) can be used to compensate for the lattice distortions in Ti:sapphire by perturbing the transmitted wavefront. The advanced MRF techniques developed allow for precise polishing of the optical inverse of lattice

  10. Modeling habit forms of sapphire crystals using the principles of periodic-bond-chain method

    NASA Astrophysics Data System (ADS)

    Bakholdin, S. I.; Maslov, V. N.

    2015-03-01

    The potential of the periodic-bond-chain method for calculating the sequence of manifestation of faces of corundum single crystals is considered. The leading role of the faces of the pinacoid, high rhombohedron, and hexagonal prism is demonstrated. The calculation results are compared with the experimental data on faceting the lateral surface of cylindrical sapphire single crystals grown by the Stepanov method and with the faceting data for crystals grown by the flux method and natural crystals.

  11. High performance sapphire windows

    NASA Technical Reports Server (NTRS)

    Bates, Stephen C.; Liou, Larry

    1993-01-01

    High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

  12. Survival of single crystal sapphire implants supporting mandibular overdentures.

    PubMed

    Berge, T I; Grønningsaeter, A G

    2000-04-01

    One hundred and sixteen sapphire (Bioceram, Kyocera) implants were inserted in 30 patients between 1984 and 1991 to support mandibular overdentures. Survival analyses were made on the basis of clinical and radiographic follow-up evaluation for 15 patients with 56 implants. For the 15 patients who were lost to follow-up, 7 of whom were deceased, reviews of records and available radiographs determined outcome and observation time. The resulting Kaplan-Meier cumulative survival rate for the sapphire implants was 68.66%, mean survival time 11.44 years, 95% confidence interval 10.56-12.32 years. Uni- and multivariate analysis using the Cox Regression model, indicated an increased risk of implant failure in patients over 60 years at time of operation, and in patients who smoke. Limited experience in implant surgery were associated with increased implant failure rate. A qualitative analysis of survived implants showed a mean annual bone loss of 0.2 mm, moderate to excellent plaque control, and excellent to good subjective global assessment of the treatment. The long-term results of the sapphire implant system used for mandibular overdenture support are inferior to other implants systems.

  13. All-glass optical fibers derived from sapphire

    NASA Astrophysics Data System (ADS)

    Dragic, Peter D.; Hawkins, Thomas; Foy, Paul; Morris, Stephanie; Ballato, John

    2013-02-01

    Increasing power levels and novel applications are demanding from fibers performance capabilities that have, to date, not been realized. One such example arises from the nascent push towards the 10-kW power threshold for narrow linewidth fiber lasers designed for applications including coherently-phased laser arrays and spectroscopic lidars. It is well-known that Brillouin scattering still restricts continued power scaling in these systems, despite several recent advances in acoustic-wave Brillouin management. Accordingly, novel fibers possessing a Brillouin gain coefficient 10 dB or more less than previously demonstrated would be of great practical benefit if they comprise novel materials in simple geometries and are manufactured using industry-accepted methods. Introducing a new and effective approach to the management of Brillouin scattering, we present on all-glass optical fibers derived from silica-clad sapphire with alumina concentrations up to 55 mole percent; considerably greater than conventionally possible enabling the design of optical fiber possessing a series of essential properties. Markedly, a Brillouin gain coefficient of 3.1 × 10-13 m/W was measured for a fiber with an average alumina concentration of 54 mole percent. This value is nearly 100 times lower than standard commercial single-mode fiber and is likely the lowest ever specified value. This reduction in Brillouin gain is enabled by a number of key material properties of the alumina-silica system, amazingly even leading to a predicted, but not yet demonstrated, composition with zero Brillouin gain. Optical fiber materials with these and other crucial properties will be discussed in the context high energy fiber laser systems.

  14. Properties Data for Adhesion and Surface Chemistry of Aluminum: Sapphire-Aluminum, Single-Crystal Couple

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Pohlchuck, Bobby; Whitle, Neville C.; Hector, Louis G., Jr.; Adams, Jim

    1998-01-01

    An investigation was conducted to examine the adhesion and surface chemistry of single-crystal aluminum in contact with single-crystal sapphire (alumina). Pull-off force (adhesion) measurements were conducted under loads of 0. I to I mN in a vacuum of 10(exp -1) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) at room temperature. An Auger electron spectroscopy analyzer incorporated directly into an adhesion-measuring vacuum system was primarily used to define the chemical nature of the surfaces before and after adhesion measurements. The surfaces were cleaned by argon ion sputtering. With a clean aluminum-clean -sapphire couple the mean value and standard deviation of pull-off forces required to separate the surfaces were 3015 and 298 micro-N, respectively. With a contaminated aluminum-clean sapphire couple these values were 231 and 241 micro-N. The presence of a contaminant film on the aluminum surface reduced adhesion by a factor of 13. Therefore, surfaces cleanliness, particularly aluminum cleanliness, played an important role in the adhesion of the aluminum-sapphire couples. Pressures on the order of 10(exp -8) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) maintained a clean aluminum surface for only a short time (less then 1 hr) but maintained a clean sapphire surface, once it was achieved, for a much longer time.

  15. Low Temperature Rhombohedral Single Crystal SiGe Epitaxy on c-plane Sapphire

    NASA Technical Reports Server (NTRS)

    Duzik, Adam J.; Choi, Sang H.

    2016-01-01

    Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (Al2O3) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100 C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550 C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

  16. Low temperature rhombohedral single crystal SiGe epitaxy on c-plane sapphire

    NASA Astrophysics Data System (ADS)

    Duzik, Adam J.; Choi, Sang H.

    2016-04-01

    Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (Al2O3) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100°C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550°C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

  17. Crystal orientation mechanism of ZnTe epilayers formed on different orientations of sapphire substrates by molecular beam epitaxy

    SciTech Connect

    Nakasu, T. Yamashita, S.; Aiba, T.; Hattori, S.; Sun, W.; Taguri, K.; Kazami, F.; Kobayashi, M.

    2014-10-28

    The electrooptic effect in ZnTe has recently attracted research attention, and various device structures using ZnTe have been explored. For application to practical terahertz wave detector devices based on ZnTe thin films, sapphire substrates are preferred because they enable the optical path alignment to be simplified. ZnTe/sapphire heterostructures were focused upon, and ZnTe epilayers were prepared on highly mismatched sapphire substrates by molecular beam epitaxy. Epitaxial relationships between the ZnTe thin films and the sapphire substrates with their various orientations were investigated using an X-ray diffraction pole figure method. (0001) c-plane, (1-102) r-plane, (1-100) m-plane, and (11-20) a-plane oriented sapphire substrates were used in this study. The epitaxial relationship between ZnTe and c-plane sapphire was found to be (111) ZnTe//(0001) sapphire with an in-plane orientation relationship of [−211] ZnTe//[1-100] sapphire. It was found that the (211)-plane ZnTe layer was grown on the m-plane of the sapphire substrates, and the (100)-plane ZnTe layer was grown on the r-plane sapphire. When the sapphire substrates were inclined from the c-plane towards the m-axis direction, the orientation of the ZnTe thin films was then tilted from the (111)-plane to the (211)-plane. The c-plane of the sapphire substrates governs the formation of the (111) ZnTe domain and the ZnTe epilayer orientation. These crystallographic features were also related to the atom arrangements of ZnTe and sapphire.

  18. Wafer-scale highly-transparent and superhydrophilic sapphires for high-performance optics.

    PubMed

    Leem, Jung Woo; Yu, Jae Su

    2012-11-19

    We reported the wafer-scale highly-transparent and superhydrophilic sapphires with antireflective subwavelength structures (SWSs) which were fabricated by dry etching using thermally dewetted gold (Au) nanomasks. Their optical transmittance properties were experimentally and theoretically investigated. The density, size, and period of the thermally dewetted Au nanopatterns can be controlled by the Au film thickness. For the sapphire with both-side SWSs at 5 nm of Au film, the average total transmittance (T(avg)) of ~96.5% at 350-800 nm was obtained, indicating a higher value than those of the flat sapphire (T(avg)~85.6%) and the sapphire with one-side SWSs (T(avg)~91%), and the less angle-dependent transmittance property was observed. The calculated transmittance results also showed a similar tendency to the measured data. The SWSs enhanced significantly the surface hydrophilicity of sapphires, exhibiting a water contact angle (θ(c)) of < 5° for Au film of 5 nm compared to θ(c)~37° of the flat sapphire. PMID:23187471

  19. Wafer-scale highly-transparent and superhydrophilic sapphires for high-performance optics.

    PubMed

    Leem, Jung Woo; Yu, Jae Su

    2012-11-19

    We reported the wafer-scale highly-transparent and superhydrophilic sapphires with antireflective subwavelength structures (SWSs) which were fabricated by dry etching using thermally dewetted gold (Au) nanomasks. Their optical transmittance properties were experimentally and theoretically investigated. The density, size, and period of the thermally dewetted Au nanopatterns can be controlled by the Au film thickness. For the sapphire with both-side SWSs at 5 nm of Au film, the average total transmittance (T(avg)) of ~96.5% at 350-800 nm was obtained, indicating a higher value than those of the flat sapphire (T(avg)~85.6%) and the sapphire with one-side SWSs (T(avg)~91%), and the less angle-dependent transmittance property was observed. The calculated transmittance results also showed a similar tendency to the measured data. The SWSs enhanced significantly the surface hydrophilicity of sapphires, exhibiting a water contact angle (θ(c)) of < 5° for Au film of 5 nm compared to θ(c)~37° of the flat sapphire.

  20. Modelling of Verneuil process for the sapphire crystal growth

    NASA Astrophysics Data System (ADS)

    Barvinschi, Floricica; Santailler, Jean-Louis; Duffar, Thierry; Le Gal, Hervé

    1999-03-01

    The finite element software FIDAP was used to simulate the Verneuil crystal growth process. The turbulent combustion between hydrogen and oxygen, giving water, the hydrodynamics of the gas phase, the inlet and outlet chemical species flow resulting from the combustion and the heat transfer in the furnace (including internal wall-to-wall radiation) are taken into account. A problem with 10 degrees of freedom per node is generated, solved and the results of the axisymmetric model have shown that the coupling of all these phenomena can be achieved in one numerical model. The effects of transparency of the crystal is discussed. A qualitative agreement between some experimental observations and the model is found, so that modelling may be a good tool for studying the Verneuil process. Nevertheless, some improvements of the model in conjunction with other experimental validations appear necessary.

  1. Ion Milling of Sapphire

    NASA Technical Reports Server (NTRS)

    Gregory, Don A.

    2002-01-01

    The ion figuring system at the Marshall Space Flight Center has been successfully used for at least three previous investigations into the ion milling of metals. The research was directed toward improving the surface quality of X-ray directing optics. These studies were performed on surfaces that were already hand polished to an excellent surface quality and were intended to remove the residual unwanted figure left by those techniques. The ion milling was typically carried out on test surfaces or mandrels that were several centimeters in width and length. The good thermal conductivity of the metal samples allowed the ion beam to be directed onto the sample for an indefinite period of time. This is not true of sapphire or most electrical insulators and problems have arisen in recent attempts to ion mill thin samples of sapphire. The failure and fracture of the material was likely due to thermal stresses and the relatively low thermal conductivity of sapphire (compared to most metals), These assumed stresses actually provided the key as to how they might be monitored. A thermal gradient in the sapphire sample will induce an effective index of refraction change and because of the shape constraint and the crystal structure and simple thermal expansion, this index change will be nonuniform across the sample. In all but simple cubic crystal structures, this leads to a spatially nonuniform optical retardance induced on any polarized optical beam traversing the sample, and it is this retardance that can be monitored using standard polarimetric procedures.

  2. Pulsed Laser Deposition of VO2 Single Crystal Thin Films on Sapphire Substrates

    NASA Astrophysics Data System (ADS)

    Zhu, Pei-ran; S, Yamamoto; A, Miyashita; H, Naramoto

    1998-12-01

    Thin films of VO2 single-crystalline on (0001) sapphire substrates have been prepared by visible pulsed laser ablation technique. The crystal quality and properties of the films are evaluated through electrical resistance measurement, x-ray diffraction (XRD), and Rutherford-backscattering spectroscopy/channeling (RBS/C) analysis. The dependence of the surface electrical resistance of the films on the temperature shows semiconductor-to-metal transitions with the resistance change of 7 × 103-2 × 104. The hysteresis widths are from less than 1 to 3 K. XRD and RBS/C data reveal that the films prepared in particular conditions are single-crystalline VO2 with the (010) planes parallel to the surface of the sapphire substrate.

  3. Photonic crystal optical memory

    NASA Astrophysics Data System (ADS)

    Lima, A. Wirth; Sombra, A. S. B.

    2011-06-01

    After several decades pushing the technology and the development of the world, the electronics is giving space for technologies that use light. We propose and analyze an optical memory embedded in a nonlinear photonic crystal (PhC), whose system of writing and reading data is controlled by an external command signal. This optical memory is based on optical directional couplers connected to a shared optical ring. Such a device can work over the C-Band of ITU (International Telecommunication Union).

  4. Optical transmission of strained GaN/sapphire structures

    NASA Astrophysics Data System (ADS)

    Kurin, S. Yu; Puzyk, M. V.; Ermakov, I. A.; Antipov, A. A.; Barash, I. S.; Roenkov, A. D.; Ratnikov, V. V.; Usikov, A. S.; Papchenko, B. P.; Helava, H.; Makarov, Yu N.; Chernyakov, A. E.

    2016-08-01

    In this work we correlated transmission spectra of GaN layers grown on sapphire substrates by hydride vapour phase epitaxy with biaxial stress measured in the layers. It was observed that the sign of stress in the GaN layer is changed by Si doping and growth conditions. Transmission curves are shifted relative to each other depending on the stress in the layer. The cut-off wavelength of the transmission curves has a tendency to shift near parallel to a shorter wavelength range when the GaN layer is under the compression biaxial stress. When the GaN layer is under the tensile biaxial stress the cut off wavelength has a tendency to shift near parallel to a longer wavelength range).

  5. A new material (single crystal sapphire screw) for internal fixation of the mandibular ramus.

    PubMed

    Iizuka, T; Fujimoto, H; Ono, T

    1987-02-01

    A new single crystal sapphire bone screw which has favourable properties such as chemical stability, mechanical strength and biocompatibility, was applied for rigid internal fixation of the sagittal split osteotomies in 86 cases since 1982. Radiographic findings supported the excellent biocompatibility of the material; there was no noticeable bone loss around the screw and the excellent bone adaptation to the threaded portion was observed. The screws can mechanically support the split mandibular rami until bone union occurs. Complications due to the screw were not encountered in follow-up periods of 0.5-3.5 years.

  6. Initial bone-implant interfaces of submergible and supramergible endosseous single-crystal sapphire implants.

    PubMed

    Akagawa, Y; Hashimoto, M; Kondo, N; Satomi, K; Takata, T; Tsuru, H

    1986-01-01

    Three types of bone-single-crystal sapphire implant interfaces were histologically determined in submergible and supramergible implant: direct bone apposition (type I), thin connective tissue with poor collagen fibers (type II), and dense fibrous connective tissue (type III). Type I interface was predominant and type III interface was sparsely seen in submergible implants. In contrast to these findings, type III interfaces frequently appeared in supramergible implants, primarily at the apical region. These differences were considered to occur by the biomechanical variable of postoperative healing.

  7. Optical properties of sapphire in its opacity range

    NASA Astrophysics Data System (ADS)

    Rogalin, V. E.; Kaplunov, I. A.; Tsenina, I. S.; Andreeva, M. S.; Filin, S. A.

    2016-06-01

    We have studied the reflection spectrum of leucosapphire in the range of 2.5-25.0 μm. Based on the analysis of the known frequency and temperature dependences of the absorption coefficient in the range of 2.5-7.0 μm, its extrapolation to the range of 10.6 μm has been performed. We have shown that the absorption coefficient in the range of 10.6 μm and in the temperature interval 300-2300 K can be evaluated as β = (2-3) × 104 cm-1. It has also been shown that the value of this characteristic correlates with the results of investigations of the action of a powerful radiation pulse of a CO2 laser on the surface of anodized aluminum. These data can be used in the development of technologies of laser processing of articles made of sapphire and ceramics based on aluminum oxide, as well as anodized articles made of aluminum alloys.

  8. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization.

  9. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization. PMID:27420499

  10. Mid-infrared silicon-on-sapphire waveguide coupled photonic crystal microcavities

    SciTech Connect

    Zou, Yi E-mail: swapnajit.chakravarty@omegaoptics.com Chen, Ray T. E-mail: swapnajit.chakravarty@omegaoptics.com; Chakravarty, Swapnajit E-mail: swapnajit.chakravarty@omegaoptics.com

    2015-08-24

    We experimentally demonstrate a photonic crystal (PC) microcavity side coupled to a W1.05 photonic crystal waveguide fabricated in silicon-on-sapphire working in mid-IR regime at 3.43 μm. Using a fixed wavelength laser source, propagation characteristics of PC waveguides without microcavity are characterized as a function of lattice constant to determine the light line position, stop gap, and guided mode transmission behavior. The resonance of an L21 PC microcavity coupled to the W1.05 PCW in the guided mode transmission region is then measured by thermal tuning of the cavity resonance across the source wavelength. Resonance quality factor ∼3500 is measured from the temperature dependency curve.

  11. Containerless laser-induced flourescence study of vaporization and optical properties for sapphire and alumina

    NASA Technical Reports Server (NTRS)

    Nordine, Paul C.; Schiffman, Robert A.

    1988-01-01

    Evaporation of aluminum oxide was studied from 1800 to 2327 K by laser-induced flourescence (LIF) detection of Al atom vapor over sapphire and alumina spheres that were levitated in an argon gas jet and heated with a continuous wave CO2 laser. Optical properties were determined from apparent specimen temperatures measured with an optical pyrometer and true temperatures deduced from the LIF intensity versus temperature measurements using the known temperature dependence of the Al atom vapor concentration in equilibrium with Al2O3. The effects of impurities and dissolved oxygen on the high-temperature optical properties of aluminum oxide were discussed.

  12. The study of optical property of sapphire irradiated with 73 MeV Ca ions

    NASA Astrophysics Data System (ADS)

    Yang, Yitao; Zhang, Chonghong; Song, Yin; Gou, Jie; Liu, Juan; Xian, Yongqiang

    2015-12-01

    Single crystals of sapphire were irradiated with 73 MeV Ca ions at room temperature to the fluences of 0.1, 0.5 and 1.0 × 1014 ions/cm2. Optical properties of these samples were characterized by ultraviolet-visible spectrometry (UV-VIS) and fluorescence spectrometer (PL). In UV-VIS spectra, it is observed the absorbance bands from oxygen single vacancy (F and F+ color centers) and vacancy pair (F2+ and F22+ color centers). The oxygen single vacancy initially increases rapidly and then does not increase in the fluence range from 0.1 to 0.5 × 1014 ions/cm2. When the fluence is higher than 0.5 × 1014 ions/cm2, oxygen single vacancy starts to increase again. Oxygen vacancy pair increases monotonically with fluence for all irradiated samples. The variation of oxygen single vacancy with fluence is probably associated with the recombination of oxygen vacancies with Al interstitials and complex defect formation (such as vacancy clusters). From PL spectra, two emission bands around 3.1 and 2.34 eV are observed. The PL intensity of the emission band around 3.1 eV decreases for all the irradiated samples. For the emission band around 2.34 eV, the PL intensity initially decreases, and then increases with fluence. Meanwhile, the peak position of the emission band around 2.34 eV gradually shifts to high energy direction with increase of fluence. The decrease of the intensity of the emission bands around 3.1 and 2.34 eV could be induced by stress from the damage layer in the irradiated samples. The shift of peak position for the emission band around 2.34 eV is induced by the appearance of emission band from Al interstitials.

  13. Long-term optical phase locking between femtosecond Ti:sapphire and Cr:forsterite lasers

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yohei; Yoshitomi, Dai; Kakehata, Masayuki; Takada, Hideyuki; Torizuka, Kenji

    2005-09-01

    Long-term optical phase-coherent two-color femtosecond pulses were generated by use of passively timing-synchronized Ti:sapphire and Cr:forsterite lasers. The relative carrier-envelope phase relation was fixed by an active feedback loop. The accumulated phase noise from 10 mHz to 1 MHz of the locked beat note was 0.43 rad, showing tight phase locking. The optical frequency fluctuation between two femtosecond combs was submillihertz, with a 1 s averaged counter measurement over 3400 s, leading to a long-term femtosecond frequency-comb connection.

  14. The study on the nanomachining property and cutting model of single-crystal sapphire by atomic force microscopy.

    PubMed

    Huang, Jen-Ching; Weng, Yung-Jin

    2014-01-01

    This study focused on the nanomachining property and cutting model of single-crystal sapphire during nanomachining. The coated diamond probe is used to as a tool, and the atomic force microscopy (AFM) is as an experimental platform for nanomachining. To understand the effect of normal force on single-crystal sapphire machining, this study tested nano-line machining and nano-rectangular pattern machining at different normal force. In nano-line machining test, the experimental results showed that the normal force increased, the groove depth from nano-line machining also increased. And the trend is logarithmic type. In nano-rectangular pattern machining test, it is found when the normal force increases, the groove depth also increased, but rather the accumulation of small chips. This paper combined the blew by air blower, the cleaning by ultrasonic cleaning machine and using contact mode probe to scan the surface topology after nanomaching, and proposed the "criterion of nanomachining cutting model," in order to determine the cutting model of single-crystal sapphire in the nanomachining is ductile regime cutting model or brittle regime cutting model. After analysis, the single-crystal sapphire substrate is processed in small normal force during nano-linear machining; its cutting modes are ductile regime cutting model. In the nano-rectangular pattern machining, due to the impact of machined zones overlap, the cutting mode is converted into a brittle regime cutting model.

  15. Random photonic crystal optical memory

    NASA Astrophysics Data System (ADS)

    Wirth Lima, A., Jr.; Sombra, A. S. B.

    2012-10-01

    Currently, optical cross-connects working on wavelength division multiplexing systems are based on optical fiber delay lines buffering. We designed and analyzed a novel photonic crystal optical memory, which replaces the fiber delay lines of the current optical cross-connect buffer. Optical buffering systems based on random photonic crystal optical memory have similar behavior to the electronic buffering systems based on electronic RAM memory. In this paper, we show that OXCs working with optical buffering based on random photonic crystal optical memories provides better performance than the current optical cross-connects.

  16. Electronically tuned Ti:sapphire laser

    SciTech Connect

    Wada, S.; Akagawa, K.; Tashiro, H.

    1996-05-01

    We have applied a birefringent acousto-optic crystal for wavelength tuning of a Ti:sapphire laser. A continuous-tuning range of 12 nm, which was limited by wavelength-dependent angle deviation of the beam deflection in the crystal, was extended to over 100 nm by optical correction. Fast and random access of lasing wavelengths by direct electronic tuning was demonstrated at a pulsed operation of 10 Hz. {copyright} {ital 1996 Optical Society of America.}

  17. Comparison between numerical modeling and experimental measurements of the interface shape in Kyropoulos growth of Ti-doped sapphire crystals

    NASA Astrophysics Data System (ADS)

    Stelian, C.; Sen, G.; Barthalay, N.; Duffar, T.

    2016-11-01

    Numerical modeling is applied to investigate the factors affecting the shape of the crystal-melt interface during the growth of Ti-doped sapphire crystals by using the Kyropoulos method. Numerical results are compared to experimental visualization of the growth interface in the case of ingots grown in crucibles of 15 cm in diameter. The transient computations of the heat transfer and melt convection show that the interface curvature depends on the internal radiative effect in the sapphire crystal. The effective thermal conductivity increases significantly in the case of Ti-doped crystals, leading to conical shapes of the interface with large curvatures. The growth interface is less curved in the case of non-doped sapphire crystals which have a smaller absorption coefficient. The convection driven by buoyancy and Marangoni effects has also a strong effect on the interface shape. The intensity of the Marangoni flow increases significantly during the shouldering stage of the growth, leading to a more curved interface with a convex-concave shape. The comparison between numerically computed interface deflection and the experimental results shows a good agreement. According to present numerical analysis, the formation of a plateau and the temporal concave shape of the crystal are related to unfavorable thermal conditions at the beginning of the growth process.

  18. Temperature dependence of the optical properties of VO2 deposited on sapphire with different orientations

    NASA Astrophysics Data System (ADS)

    Nazari, Mohammad; Zhao, Yong; Kuryatkov, Vladimir; Fan, Zhaoyang; Bernussi, Ayrton; Holtz, Mark

    2012-10-01

    Vanadium dioxide exhibits a reversible first-order metal-insulator phase transition (MIT) at temperature TMIT= 350 K. The transformation brings structural phase transition and abrupt changes in electrical conductivity and optical properties. Despite intensive studies of this material, little is understood about the optical properties and their connection with the structural properties across the phase transition. We report spectroscopic ellipsometry and Raman investigations of the optical properties of vanadium dioxide on sapphire substrates with c-, m- and r- orientations. For the m- and r-plane substrates, VO2 is strained such that the material transforms from the monoclinic M1 phase directly to the rutile R structure. In contrast, c-plane sapphire produces strains favoring transformation from M1 into monoclinic M2 material, prior to reaching the R phase. These structural differences result in distinct variations of the optical transitions observed in the ellipsometry results. While in m-plane sample the energy gap collapses over a narrow temperature range, for the c-plane case, a broad temperature range is obtained over which the energy gap is small but not fully collapsed. Raman studies show diverse phonon behavior across the phase transitions.

  19. Optimization of the structural quality of sapphire rods grown by the Stepanov method in a reducing atmosphere

    SciTech Connect

    Kryvonosov, Ye. V.; Konevskiy, P. V. Lytvynov, L. A.; Tkachenko, V. F.

    2015-03-15

    Historically, the Stepanov method has been used for growing long shaped sapphire crystals (rods, tubes, and ribbons) for practical design. The recent intense development of this technique was stimulated by sapphire applications in optics and electronics; thus, the optical and structural quality of these crystals is of great importance. The results of studying the structural quality of sapphire rods up to 18 mm in diameter grown under optimized conditions are reported.

  20. Laser-induced microexplosion confined in the bulk of a sapphire crystal: evidence of multimegabar pressures.

    PubMed

    Juodkazis, S; Nishimura, K; Tanaka, S; Misawa, H; Gamaly, E G; Luther-Davies, B; Hallo, L; Nicolai, P; Tikhonchuk, V T

    2006-04-28

    Extremely high pressures (approximately 10 TPa) and temperatures (5 x 10(5) K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 10(14) W/cm2 converting material within the absorbing volume of approximately 0.2 microm3 into plasma in a few fs. A pressure of approximately 10 TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 10(18) K/s can, thus, be studied in a well-controlled laboratory environment.

  1. Bulk vertical micromachining of single-crystal sapphire using inductively coupled plasma etching for x-ray resonant cavities

    NASA Astrophysics Data System (ADS)

    Chen, P.-C.; Lin, P.-T.; Mikolas, D. G.; Tsai, Y.-W.; Wang, Y.-L.; Fu, C.-C.; Chang, S.-L.

    2015-01-01

    To provide coherent x-ray sources for probing the dynamic structures of solid or liquid biological substances on the picosecond timescale, a high-aspect-ratio x-ray resonator cavity etched from a single crystal substrate with a nearly vertical sidewall structure is required. Although high-aspect-ratio resonator cavities have been produced in silicon, they suffer from unwanted multiple beam effects. However, this problem can be avoided by using the reduced symmetry of single-crystal sapphire in which x-ray cavities may produce a highly monochromatic transmitted x-ray beam. In this study, we performed nominal 100 µm deep etching and vertical sidewall profiles in single crystal sapphire using inductively coupled plasma (ICP) etching. The large depth is required to intercept a useful fraction of a stopped-down x-ray beam, as well as for beam clearance. An electroplated Ni hard mask was patterned using KMPR 1050 photoresist and contact lithography. The quality and performance of the x-ray cavity depended upon the uniformity of the cavity gap and therefore verticality of the fabricated vertical sidewall. To our knowledge, this is the first report of such deep, vertical etching of single-crystal sapphire. A gas mixture of Cl2/BCl3/Ar was used to etch the sapphire with process variables including BCl3 flow ratio and bias power. By etching for 540 min under optimal conditions, we obtained an x-ray resonant cavity with a depth of 95 µm, width of ~30 µm, gap of ~115 µm and sidewall profile internal angle of 89.5°. The results show that the etching parameters affected the quality of the vertical sidewall, which is essential for good x-ray resonant cavities.

  2. Single-crystal sapphire resonator at millikelvin temperatures: Observation of thermal bistability in high-Q factor whispering gallery modes

    SciTech Connect

    Creedon, Daniel L.; Tobar, Michael E.; Le Floch, Jean-Michel; Reshitnyk, Yarema; Duty, Timothy

    2010-09-01

    Resonance modes in single crystal sapphire ({alpha}-Al{sub 2}O{sub 3}) exhibit extremely high electrical and mechanical Q factors ({approx_equal}10{sup 9} at 4 K), which are important characteristics for electromechanical experiments at the quantum limit. We report the cool down of a bulk sapphire sample below superfluid liquid-helium temperature (1.6 K) to as low as 25 mK. The electromagnetic properties were characterized at microwave frequencies, and we report the observation of electromagnetically induced thermal bistability in whispering gallery modes due to the material T{sup 3} dependence on thermal conductivity and the ultralow dielectric loss tangent. We identify ''magic temperatures'' between 80 and 2100 mK, the lowest ever measured, at which the onset of bistability is suppressed and the frequency-temperature dependence is annulled. These phenomena at low temperatures make sapphire suitable for quantum metrology and ultrastable clock applications, including the possible realization of the quantum-limited sapphire clock.

  3. Mandibular single crystal sapphire implants: changes in crestal bone levels over three years.

    PubMed

    Fartash, B; Eliasson, S; Arvidson, K

    1995-09-01

    A total of 190 single crystal sapphire implants, 85 short (4S9S) and 105 long (4S9L), were monitored with panoramic and intraoral radiographs for 3 years. The implants were used as abutments for overdentures in edentulous mandibles in 51 patients. Within the first year, 2 patients lost one implant each due to pain and lack of osseointegration. Neither was replaced and the superstructures remained stable. At baseline registration, i.e., immediately after the prosthetic installation, the bone height relative to the length of the implant was calculated. The mean bone implant score (BIS) was 63.55 +/- 1.34% (mean +/- SE). BIS decreased during the first year 62.18 +/- 1.51%. At the 2- and 3-year recordings, the mean BIS were 61.81 +/- 1.58% and 61.73 +/- 1.63%, respectively. There were no statistically significant differences in BIS changes over the 3-year period or between men and women. The decrease in mean BIS was greater for implants in the premolar region than in the incisor region and for short implants than for long implants.

  4. Temperature dependence of the optical properties of VO2 deposited on sapphire with different orientations

    NASA Astrophysics Data System (ADS)

    Nazari, M.; Zhao, Y.; Kuryatkov, V. V.; Fan, Z. Y.; Bernussi, A. A.; Holtz, M.

    2013-01-01

    Spectroscopic ellipsometry studies are reported for vanadium dioxide grown on c-, m-, and r-plane sapphire substrates. The crystallographic orientation of the VO2 depends strongly on the substrate, producing diverse strains in the layers which affect the interband transition energies and the phase transition temperatures. These structural differences correlate with distinct variations of the optical transitions observed in the ellipsometry results. For the m- and r-plane substrates, the VO2 appears to transform abruptly from the monoclinic phase to the rutile R structure as temperature is increased. In contrast, VO2 deposited on c-plane sapphire exhibits a sluggish transformation. For the m-plane sample, the energy gap collapses over a narrow temperature range. For the c-plane case, a broad temperature range is obtained between the onset and completion of the transformation. Raman studies of the vibrational structure show that internal stresses due to expansion and contraction across the phase transitions impacts the observed phonon energies.

  5. Optical anisotropy of ZnO nanocrystals on sapphire by thermoreflectance spectroscopy.

    PubMed

    Ho, Ching-Hwa; Chen, Yi-Jia; Jhou, Huang-Wei; Du, Jhih-Han

    2007-09-15

    The band-edge excitonic transitions of vertically aligned and tilted ZnO nanorods on sapphire have been characterized using thermoreflectance (TR) measurements in the temperature range between 30 and 300 K. The TR spectra of the nanorods with largely {0001} planes show considerable difference in energy and line shape with respect to those of the other sample with largely side planes of {1010}. The TR result at each temperature clearly indicates the band-edge excitons (A, B, and C) measured from the largely {0001} planes of the rods are lower in energy with respect to those obtained from the other sample dominated by the side planes of {1010}. Optical anisotropy in the transition amplitudes of the TR spectra for the vertically aligned and tilted ZnO nanorods is observed. The TR is shown to be very sensitive to the detection of the ZnO nanorods' alignment.

  6. Ultrabroadband noncollinear optical parametric amplification with LBO crystal.

    PubMed

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2008-11-10

    Ultrabroadband visible noncollinear optical parametric amplification (NOPA) was achieved in an LBO crystal, with a continuum seed pulse generated from a sapphire plate. The spectral bandwidth of the amplified visible pulse was about 200 nm, which can support sub-5 fs pulse amplification. An amplified output of 0.21 microJ with an average gain of about 210 was achieved. This provides, to the best of our knowledge, the first-time demonstration of such broadband amplification with a biaxial nonlinear optical crystal. Both the simulation and experimental results indicate that the LBO has a great potential as nonlinear medium in power amplifier for TW to PW noncollinear optical parametric chirped pulse amplification (NOPCPA) systems. PMID:19581976

  7. Silicon-Based Optical Waveguide Modulators and Mode-Locked TITANIUM:SAPPHIRE Laser Dynamics.

    NASA Astrophysics Data System (ADS)

    Liu, Yanming

    Single-mode deeply-etched silicon-germanium/silicon (SiGe/Si) rib waveguides have been fabricated and characterized with low propagation losses and strong guiding. Such a waveguide structure is suitable for bent waveguide devices and provides efficient field overlapping, which is needed for devices requiring strong nonlinear coupling. Using the deeply-etched waveguide technique, we have fabricated Si/SiGe/Si Mach-Zehnder modulators, which show strong single-mode waveguiding but only small electro -optic modulation has been observed so far. Another Si modulator is a Fabry-Perot interferometer. We have demonstrated all-optical modulation at 1.3 μm and 1.5 μm in the reflection mode of the asymmetric Si Fabry-Perot interferometer by a control light beam at 0.85 mum. Both switching -on and switching-off operations are demonstrated by transversely moving the etalon. In addition, we have analyzed that silicon carbide (SiC) waveguides exhibit low loss for fundamental modes and high loss for higher-order modes at wavelengths from 0.6 to 1.6 mum. Electro-optic modulation is analyzed with a SiC-on-SiO_2 waveguide structure. Such modulators are potential candidates for high-speed electro-optic modulation for silicon-based optoelectronic devices. Furthermore, we studied the dynamics of a Kerr -lens self-mode-locked Ti:sapphire laser, generating 40 -fs pulses and tunable from 750 nm to 920 nm. A moving mirror was first proposed as a starting mechanism for self -mode locking and the starting dynamics is studied in detail. In addition, periodic pulse-train amplitude modulations have been observed and studied. The observation of the amplitude modulation further confirms the dynamic Kerr-lens self -focusing model of self-mode locking in Ti:sapphire lasers and helps us better understand the laser performance. Furthermore, dual-wavelength mode locking is observed over a broad tuning range, which would be very useful for two-wavelength subpicosecond optical sampling, such as pump

  8. 1 Hz linewidth Ti:sapphire laser as local oscillator for (40)Ca(+) optical clocks.

    PubMed

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled (40)Ca(+) ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10(-14)) is observed. This laser is also used as the local oscillator for the comparison experiment of two (40)Ca(+) ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  9. 1 Hz linewidth Ti:sapphire laser as local oscillator for (40)Ca(+) optical clocks.

    PubMed

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled (40)Ca(+) ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10(-14)) is observed. This laser is also used as the local oscillator for the comparison experiment of two (40)Ca(+) ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results. PMID:27370440

  10. 1 Hz linewidth Ti:sapphire laser as local oscillator for 40Ca+ optical clocks

    NASA Astrophysics Data System (ADS)

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10-15 frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled 40Ca+ ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10-14) is observed. This laser is also used as the local oscillator for the comparison experiment of two 40Ca+ ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  11. Anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using double AlN buffer layers.

    PubMed

    Zhao, Guijuan; Wang, Lianshan; Yang, Shaoyan; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Wang, Zhanguo

    2016-02-10

    We report the anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11-22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1-100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting.

  12. Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

    PubMed Central

    Zhao, Guijuan; Wang, Lianshan; Yang, Shaoyan; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Wang, Zhanguo

    2016-01-01

    We report the anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11–22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1–100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting. PMID:26861595

  13. Liquid-Crystal Optical Correlator

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1989-01-01

    Optical correlator uses commercially-available liquid-crystal television (LCTV) screen as spatial light modulator. Correlations with this device done at video frame rates, making such operations as bar-code recognition possible at reasonable cost. With further development, such correlator useful in automation, robotic vision, and optical image processing.

  14. Comparative evaluation of chewing function with removable partial dentures and fixed prostheses supported by the single-crystal sapphire implant in the Kennedy Class II partially edentulous mandible.

    PubMed

    Akagawa, Y; Okane, H; Kondo, N; Tsuga, K; Tsuru, H

    1989-01-01

    Differential chewing function with removable partial dentures (RPDs) and fixed prostheses supported by the single-crystal sapphire implant was evaluated in five subjects with Kennedy Class II partially edentulous mandibles by means of electromyography. Rehabilitation with the single-crystal sapphire implant resulted in regular chewing patterns with a low variation coefficient and higher activity of chewing-side masticatory muscles compared to RPD rehabilitation. This difference in chewing function between the two rehabilitation modalities could be the result of differences in stability of occlusion and neurophysiologic feedback systems.

  15. Growth Of Large-Diameter Crystals By Hem Tmfor Optical And Laser Applications

    NASA Astrophysics Data System (ADS)

    Khattak, C. P.; Schmid, F.

    1984-12-01

    The Heat Exchanger Method (HEM), a new crystal growth process, is in commercial production for 20 cm diameter sapphire crystals and 40 cm diameter silicon ingots for optical applications. The simplicity of the HEM combined with a very high degree of control of the submerged, solid-liquid interface allows growth of high-quality crystals. The HEM is also being adapted for the growth of Co:MgF2, Ti:A1203 and Cr:A1203 crystals for laser applications.

  16. High refractive index immersion liquid for superresolution 3D imaging using sapphire-based aplanatic numerical aperture increasing lens optics.

    PubMed

    Laskar, Junaid M; Shravan Kumar, P; Herminghaus, Stephan; Daniels, Karen E; Schröter, Matthias

    2016-04-20

    Optically transparent immersion liquids with refractive index (n∼1.77) to match the sapphire-based aplanatic numerical aperture increasing lens (aNAIL) are necessary for achieving deep 3D imaging with high spatial resolution. We report that antimony tribromide (SbBr3) salt dissolved in liquid diiodomethane (CH2I2) provides a new high refractive index immersion liquid for optics applications. The refractive index is tunable from n=1.74 (pure) to n=1.873 (saturated), by adjusting either salt concentration or temperature; this allows it to match (or even exceed) the refractive index of sapphire. Importantly, the solution gives excellent light transmittance in the ultraviolet to near-infrared range, an improvement over commercially available immersion liquids. This refractive-index-matched immersion liquid formulation has enabled us to develop a sapphire-based aNAIL objective that has both high numerical aperture (NA=1.17) and long working distance (WD=12  mm). This opens up new possibilities for deep 3D imaging with high spatial resolution. PMID:27140083

  17. High refractive index immersion liquid for superresolution 3D imaging using sapphire-based aplanatic numerical aperture increasing lens optics.

    PubMed

    Laskar, Junaid M; Shravan Kumar, P; Herminghaus, Stephan; Daniels, Karen E; Schröter, Matthias

    2016-04-20

    Optically transparent immersion liquids with refractive index (n∼1.77) to match the sapphire-based aplanatic numerical aperture increasing lens (aNAIL) are necessary for achieving deep 3D imaging with high spatial resolution. We report that antimony tribromide (SbBr3) salt dissolved in liquid diiodomethane (CH2I2) provides a new high refractive index immersion liquid for optics applications. The refractive index is tunable from n=1.74 (pure) to n=1.873 (saturated), by adjusting either salt concentration or temperature; this allows it to match (or even exceed) the refractive index of sapphire. Importantly, the solution gives excellent light transmittance in the ultraviolet to near-infrared range, an improvement over commercially available immersion liquids. This refractive-index-matched immersion liquid formulation has enabled us to develop a sapphire-based aNAIL objective that has both high numerical aperture (NA=1.17) and long working distance (WD=12  mm). This opens up new possibilities for deep 3D imaging with high spatial resolution.

  18. Structural and optical properties of low temperature grown AlN films on sapphire using helicon sputtering system

    SciTech Connect

    Chen, Meei-Ru; Chen, Hou-Guang; Kao, Hui-Ling Wu, Ming-Guei; Tzou, An-Jye; Chen, Jyh Shin; Chou, Hsiung

    2015-05-15

    AlN thin films have been deposited directly on c-plane sapphire substrates at low temperatures by a helicon sputtering system. The structural quality of AlN epitaxial films was characterized by x-ray diffractometry and transmission electron microscopy. The films exhibit smooth surface with root-mean-square roughness as small as 0.7 nm evaluated by atomic force microscope. The optical transmittance spectra show a steep absorption edge at the wavelength of 200 nm and a high transmittance of over 80% in the visible range. The band-edge transition (6.30 eV) of AlN film was observed in the cathodoluminescence spectrum recorded at 11 K. The spectral response of metal–semiconductor–metal photodetectors constructed with AlN/sapphire reveals the peak responsivity at 200 nm and a UV/visible rejection ratio of about two orders of magnitude. The results of this low temperature deposition suggest the feasibility of the epitaxial growth of AlN on sapphire substrates and the incorporation of the AlN films in the surface acoustic wave devices and the optical devices at deep ultraviolet region.

  19. Measurement of nonlinear optical refraction of composite material based on sapphire with silver by Kerr-lens autocorrelation method.

    PubMed

    Yu, Xiang-xiang; Wang, Yu-hua

    2014-01-13

    Silver nanoparticles synthesized in a synthetic sapphire matrix were fabricated by ion implantation using the metal vapor vacuum arc ion source. The optical absorption spectrum of the Ag: Al2O3 composite material has been measured. The analysis of the supercontinuum spectrum displayed the nonlinear refractive property of this kind of sample. Nonlinear optical refraction index was identified at 800 nm excitation using the Kerr-lens autocorrelation (KLAC) technique. The spectrum showed that the material possessed self-defocusing property (n(2) = -1.1 × 10(-15) cm(2)W). The mechanism of nonlinear refraction has been discussed.

  20. Optics of globular photonic crystals

    SciTech Connect

    Gorelik, V S

    2007-05-31

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter {approx}200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  1. Histology of tissues surrounding single crystal sapphire endosseous dental implants: an experimental study in the beagle dog.

    PubMed

    Fartash, B; Arvidson, K; Ericsson, I

    1990-12-01

    9 single crystal sapphire dental implants were installed bilaterally into pre-extracted areas in the lower jaw of two beagle dogs and histologically analysed after 180 days in situ. 8 implants were stable and radiographs disclosed complete bone healing. Light-, scanning- and transmission electron microscopy demonstrated that the stable implants were surrounded by a mineralizing bone boundary and a mucosa nearly free from inflammatory cell infiltrations. The 9th implant was mobile and surrounded by a non-mineralized connective tissue capsule containing bundles of collagen. The ultrastructure of the mucosa surrounding the implants closely resembled the mucosa surrounding the tooth. Histometric analysis of the alveolar bone surrounding the stable implants revealed that the value of the bone contact surface ranged from 37.1% to 86.9% (mean value 61.8%) at the light microscopic level.

  2. Optimization of a femtosecond Ti : sapphire amplifier using a acouto-optic programmable dispersive filter and a genetic algorithm.

    SciTech Connect

    Korovyanko, O. J.; Rey-de-Castro, R.; Elles, C. G.; Crowell, R. A.; Li, Y.

    2006-01-01

    The temporal output of a Ti:Sapphire laser system has been optimized using an acousto-optic programmable dispersive filter and a genetic algorithm. In-situ recording the evolution of spectral phase, amplitude and temporal pulse profile for each iteration of the algorithm using SPIDER shows that we are able to lock the spectral phase of the laser pulse within a narrow margin. By using the second harmonic of the CPA laser as feedback for the genetic algorithm, it has been demonstrated that severe mismatch between the compressor and stretcher can be compensated for in a short period of time.

  3. Optical Magnetometer Incorporating Photonic Crystals

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Florescu, Lucia

    2007-01-01

    According to a proposal, photonic crystals would be used to greatly increase the sensitivities of optical magnetometers that are already regarded as ultrasensitive. The proposal applies, more specifically, to a state-of-the-art type of quantum coherent magnetometer that exploits the electromagnetically-induced-transparency (EIT) method for determining a small change in a magnetic field indirectly via measurement of the shift, induced by that change, in the hyperfine levels of resonant atoms exposed to the field.

  4. Influence of the crucible geometry on the shape of the melt crystal interface during growth of sapphire crystal using a heat exchanger method

    NASA Astrophysics Data System (ADS)

    Chen, Jyh-Chen; Lu, Chung-Wei

    2004-05-01

    Computer simulations using the commercial code FIDAP, which is based on finite element techniques, were performed to investigate the effect of the shape of the crucible on the temperature distribution, velocity distribution and shape of the melt-crystal interface, during the application of the heat exchanger method (HEM) of growing sapphire crystals. Heat transfer from the furnace to the crucible and heat extraction from the heat exchanger can be modeled by the convection boundary conditions. Cylindrical crucibles with differently curved corners at their base are considered. The curved base of the crucible decreases the convexity of the melt-crystal interface and suppresses the appearance of "hot spots". A hemispherically shaped crucible base yields the lowest maximum convexity. The variation in convexity of the melt-crystal interface is less abrupt for a cylindrical crucible with curved corners at the base than one without curved corners. The effects of the thickness and the conductivity of the crucible are also addressed. The convexity of the melt-crystal interface decreases as the thickness of the crucible wall increases. The convexity also declines as the conductivity of the crucible increases.

  5. Characterization of critically cleaned sapphire single-crystal substrates by atomic force microscopy, XPS and contact angle measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Wang, You; Gan, Yang

    2013-06-01

    A contaminant-free surface of single-crystal α-Al2O3 (or sapphire) substrates is key to the experimental studies of its surface and interfacial properties at ambient conditions. Here we critically evaluated methods reported in the literature using comprehensive surface analysis techniques including atomic force microscopy, XPS and contact angle measurements. We found that reported methods did not perform well in terms of removing both organic and particulate contaminants from the (0 0 0 1) basal surface. After thoroughly examining the cleaning effect of various chemical solutions and UV light and plasma irradiation, and based on modified RCA cleaning protocols, we proposed a new wet-cleaning method showing outstanding cleaning performance. This new reliable method will be very useful for the next-step surface chemistry study of single-crystal α-Al2O3. It was also demonstrated that AFM, due to its high spatial resolution and sensitivity as a local probe technique, was an indispensable tool for surface contamination control studies.

  6. Determination of Second-Order Nonlinear Optical Susceptibility of GaN Films on Sapphire

    NASA Astrophysics Data System (ADS)

    Fujita, Takashi; Hasegawa, Tatsuo; Haraguchi, Masanobu; Okamoto, Toshihiro; Fukui, Masuo; Nakamura, Syuji

    2000-05-01

    The second-order nonlinear susceptibilities of GaN films on sapphire were determined by the Maker fringe technique. In deriving the second-harmonic intensity, the bound wave propagating from the GaN-air interface to the GaN-sapphire interface and that propagating in the opposite direction were taken into account. We obtained |χ(2)zxx|=14.7±0.2 pm/V, |χ(2)xzx|=14.4±0.2 pm/V and |χ(2)zzz|=29.7±0.7 pm/V for the GaN film with a thickness of 2.55 μm using fundamental light with a wavelength of 1.064 μm.

  7. Dual Femtosecond TITANIUM:SAPPHIRE Laser for Ultrafast Optical Sampling Two-Color Pump/probe Studies.

    NASA Astrophysics Data System (ADS)

    Luo, Ningyi Daniel

    A pair of self-synchronous Ti:Sapphire lasers have been setup for two-color pump/probe detection in the sub-picosecond time regime. The two 75 femtosecond self -mode-locked Ti:Sapphire lasers are operated asynchronously at slightly different repetition rates to provide continuously varying dynamic delay times. They are tunable at 700-890 nm. The shorter wavelength pulses from one laser are used as a pump source, while the longer wavelength pulses are used as a probe. The sum-frequency pulses generated by the cross-correlation of the two laser pulses are used to define the "time-zero" position and trigger the pump/probe process. The experiment is triggered at the difference frequency, and the signal can be averaged many times allowing a weak signal to build up. Dual-time scale is involved with the interpretation of the signal, which allows the experiment to be carried on the real time scale and the signal to be recorded on a much reduced equivalent time scale. Excited state lifetime measurement of laser HITCI has proven that this technology is practically feasible. Several advantages have been seen: (1) independent wavelength tunability of the pump and probe lasers; (2) variable femto- to nano -second pump/probe time delay; (3) fast (mu s-ms) data collection time; (4) compact optical layout, without the need for optical delay lines and modulators, and thus, simple optical alignment. This study sheds light on the development of a novel compact high speed optical instrument.

  8. Pulsed modification of germanium films on silicon, sapphire, and quartz substrates: Structure and optical properties

    SciTech Connect

    Novikov, H. A.; Batalov, R. I. Bayazitov, R. M.; Faizrakhmanov, I. A.; Lyadov, N. M.; Shustov, V. A.; Galkin, K. N.; Galkin, N. G.; Chernev, I. M.; Ivlev, G. D.; Prokop’ev, S. L.; Gaiduk, P. I.

    2015-06-15

    The structural and optical properties of thin Ge films deposited onto semiconducting and insulating substrates and modified by pulsed laser radiation are studied. The films are deposited by the sputtering of a Ge target with a low-energy Xe{sup +} ion beam. Crystallization of the films is conducted by their exposure to nanosecond ruby laser radiation pulses (λ = 0.694 μm) with the energy density W = 0.2−1.4 J cm{sup −2}. During pulsed laser treatment, the irradiated area is probed with quasi-cw (quasi-continuous-wave) laser radiation (λ = 0.532 and 1.064 μm), with the reflectance recorded R(t). Experimental data on the lifetime of the Ge melt are compared with the results of calculation, and good agreement between them is demonstrated. Through the use of a number of techniques, the dependences of the composition of the films, their crystal structure, the level of strains, and the reflectance and transmittance on the conditions of deposition and annealing are established.

  9. Determining Optical Axes of Uniaxial Crystals

    NASA Technical Reports Server (NTRS)

    Schock, H. J.; Regan, C. A.; Lock, J. A.

    1987-01-01

    Polarizing-microscope concept adapted for thick samples. Optical axis of crystal usually found by examining sample thinner than 1 mm between crossed polarizing plates. Frequently impractical to cut off small sample of crystal for testing, technique modified to accommodate large crystals. Ability to circumvent effect of birefringence has applications where laser beams must be transmitted through uniaxial crystals, as in laser diagnostics of contained flows in systems requiring windows for optical access.

  10. Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing

    NASA Astrophysics Data System (ADS)

    Zhao, Mingtao; Huang, Yong; Kang, Jin U.

    2013-03-01

    We describe a novel common-path optical coherence tomography (CP-OCT) fiber probe design using a sapphire ball lens for cross-sectional imaging and sensing in retina vitrectomy surgery. Single mode Gaussian beam (TEM00) simulation was used to optimize lateral resolution and working distance (WD) of the common-path probe. A theoretical sensitivity model for CP-OCT was prosed to assess its optimal performance based an unbalanced photodetector configuration. Two probe designs with working distances (WD) 415μm and 1221μm and lateral resolution 11μm and 18μm, respectively were implemented with sensitivity up to 88dB. The designs are also fully compatible with conventional Michelson interferometer based OCT configurations. The reference plane of the probe, located at the distal beam exit interface of the single mode fiber (SMF), was encased within a 25-gauge hypodermic needle by the sapphire ball lens facilitates its applications in bloody and harsh environments. The performances of the fiber probe with 11μm of lateral resolution and 19μm of axial resolution were demonstrated by cross-sectional imaging of a cow cornea and retina in vitro with a 1310nm swept source OCT system. This probe was also attached to a piezoelectric motor for active compensation of physiological tremor for handheld retinal surgical tools.

  11. Influence of gamma-irradiation sterilization on the structural defects of sapphire single crystals (alpha-Al(2)O(3)).

    PubMed

    Dubois, J C; Jardin, C; Exbrayat, P; Lissac, M; Treheux, D

    2001-01-01

    The influence of sterilization by gamma rays on the structure and the electrical behaviour of sapphire single crystal (alpha-Al(2)O(3)) was studied successively by thermoluminescence, by cathodoluminescence and by observation of the scanning electron microscope mirror effect. The mirror method allowed us to measure the capacity of an insulating material to trap electrons. The structural analysis of the alpha-Al(2)O(3) showed that there were oxygen vacancies, as well as chromium and titanium impurities. It was possible to demonstrate that these defects, especially the oxygen vacancies, are in a different state after a 30 kilogray irradiation. The valency state changes of these defects and the presence of trapped charges are accompanied by a deformation of the crystalline lattice which results in a modification of its electrical properties. At room temperature, the irradiated alpha-Al(2)O(3), unlike non irradiated alpha-Al(2)O(3), is capable of trapping electrons. It can be concluded that gamma-ray sterilization modifies the cohesive energy of alpha-Al(2)O(3), which could lead to mechanical changes (surface charge, friction, wear, fracture strength, em leader) in this material. PMID:11564909

  12. Long-term evaluation of single crystal sapphire implants as abutments in fixed prosthodontics.

    PubMed

    Fartash, B; Arvidson, K

    1997-02-01

    49 patients participated in a prospective study of treatment of total or partial edentulism with fixed prosthodontics supported by Bioceram sapphire implants. 15 patients were treated for maxillary or mandibular edentulism, and 7 for a missing maxillary anterior tooth. The remaining 27 patients, with Applegate-Kennedy Class I-IV residual dentitions, were treated with fixed bridges supported by free-standing implants, or bridges supported by teeth and implants. Implant success, prosthesis stability, radiographic marginal bone level as well as parameters for peri-implant health were evaluated. The study began in 1982, and clinical treatment of the last patients was completed in 1988, i.e., a follow-up period ranging from 7 to 13 years. Of the patients treated for total mandibular edentulism, one implant fractured after 6 years in situ. The bone implant score (BIS) values for those implants were at the time for the bridge cementation 63.5 +/- 1.4 and at 1, 2, 3 and 5 year follow-ups 62.1 +/- 1.4, 61.9 +/- 1.5, 61.5 +/- 1.6, and 60.95 +/- 1.3, respectively. The success rate was 100%, 100% and 97.7% for the mandible at 3, 5 and 10 years, respectively. Of the 7 edentulous patients treated with maxillary fixed bridges, 6 implants in 1 patient had to be removed after 1 year in service. Another 2 patients lost all their implants, 6 each, after 36 months. 6 implants in the 4th patient did not fulfil the criteria for success and were rated as failures at the four year follow-up. The success rate was thus 58.1%, 44.2% and 44.2% for the maxilla at 3, 5 and 10 year follow-ups, respectively. Of the 7 patients in whom single missing teeth were replaced, 1 implant in the premolar region was lost during the 1st year post-operatively, but no other complications or changes in BIS were observed. Of the 27 patients treated for partial edentulism (56 implants total) 1 implant, of a 4-unit free standing maxillary bridge fractured after 6 years and was later replaced. There were no

  13. Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

    NASA Technical Reports Server (NTRS)

    Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

    1988-01-01

    Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

  14. Molecular beam epitaxy growth and optical properties of single crystal Zn3N2 films

    NASA Astrophysics Data System (ADS)

    Wu, Peng; Tiedje, T.; Alimohammadi, H.; Bahrami-Yekta, V.; Masnadi-Shirazi, M.; Wang, Cong

    2016-10-01

    Single crystal Zn3N2 films with (100) orientation have been grown by plasma-assisted molecular beam epitaxy on MgO and A-plane sapphire substrates with in situ optical reflectance monitoring of the growth. The optical bandgap was found to be 1.25-1.28 eV and an electron Hall mobility as high as 395 cm2 V-1 s-1 was measured. The films were n-type with carrier concentrations in the 1018-1019 cm-3 range.

  15. Optical Evaluation of DMDs with UV-Grade FS, Sapphire, MgF2 Windows and Reflectance of Bare Devices

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Heap, Sara; Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Roberto, Massimo

    2016-01-01

    Digital Micro-mirror Devices (DMDs) have been identified as an alternative to microshutter arrays for space-based multi-object spectrometers (MOS). Specifically, the MOS at the heart of a proposed Galactic Evolution Spectroscopic Explorer (GESE) that uses the DMD as a reprogrammable slit mask. Unfortunately, the protective borosilicate windows limit the use of DMDs in the UV and IR regimes, where the glass has insufficient throughput. In this work, we present our efforts to replace standard DMD windows with custom windows made from UV-grade fused silica, Low Absorption Optical Sapphire (LAOS) and magnesium fluoride. We present reflectance measurements of the antireflection coated windows and a reflectance study of the DMDs active area (window removed). Furthermore, we investigated the long-term stability of the DMD reflectance and recoating device with fresh Al coatings.

  16. Optical diagnostics of the laser-induced phase transformations in thin germanium films on silicon, sapphire, and fused silica

    NASA Astrophysics Data System (ADS)

    Novikov, H. A.; Batalov, R. I.; Bayazitov, R. M.; Faizrakhmanov, I. A.; Ivlev, G. D.; Prokop'ev, S. L.

    2015-03-01

    The in-situ procedure is used to study the modification of thin (200-600 nm) germanium films induced by nanosecond pulses of a ruby laser. The films are produced using the ion-beam or magnetron sputtering on single-crystalline silicon (Si), sapphire (Al2O3), and fused silica (α-SiO2) substrates. The results on the dynamics of the laser-induced processes are obtained using the optical probing of the irradiated region at wavelengths of λ = 0.53 and 1.06 μm. The results of probing make it possible to determine the threshold laser energy densities that correspond to the Ge and Si melting and the generation of the Ge ablation plasma versus the amount of deposited Ge and thermophysical parameters of the substrate. The reflection oscillograms are used to obtain the dependences of the melt lifetime on the laser-pulse energy density.

  17. Na-doped optical Germanium bulk crystals

    NASA Astrophysics Data System (ADS)

    Pekar, G. S.; Singaevsky, A. F.

    2012-09-01

    In an effort to develop a material for infrared (IR) optics with improved parameters, bulk crystals of optical germanium doped with Na have been first grown and studied. Single-crystalline and coarse-crystalline Ge:Na boules of different shapes and dimensions, up to 10 kg by weight, have been grown. Sodium was incorporated into the Ge crystal during the crystal growing from the melt. Despite the fact that Na contamination in the source material was not strictly controlled, the density of Na in the grown crystals determined by the neutron activation analysis as well as by the glow discharge mass spectrometry did not exceed 1015 cm-3. Just this value may be supposed to be close to the solubility limit of Na incorporated in Ge in the course of bulk crystal growth. A first demonstration of donor behavior of Na in bulk Ge crystals is made by means of a thermoelectric type of testing. An interstitial location of Na impurity has been verified by experiments on donor drift in the dc electric field. The crystals are grown with free electron density in the range from 5ṡ1013 to 4ṡ1014 cm-3 which is optimal for using Ge crystals as an optical material for fabricating passive elements of the IR technique. A comparison between the properties of Ge:Na crystals and Ge crystals doped with Sb, a conventional impurity in optical germanium, grown under the same technological conditions and from the same intrinsic Ge as a source material, revealed a number of advantages of Ge:Na crystals; among them, the higher transparency in the IR region, smaller radiation scattering and higher regular optical transmission, lower dislocation density, more uniform distribution of electrical and optical characteristics over the crystal volume, the identity of optical parameters in the single-crystalline, and coarse-crystalline boules. No degradation of optical elements fabricated from Ge:Na crystals was detected in the course of their commercial application, starting from 1998.

  18. Intense laser propagation in sapphire

    NASA Astrophysics Data System (ADS)

    Tate, Jennifer L.

    When a sufficiently energetic short laser pulse propagates through a medium it can generate an explosive increase in bandwidth leading to the creation of white light; this is known as supercontinuum generation (SCG). Although it is frequently referred to as a single process, SCG is actually the result of many different parallel and competing processes. In this work we investigate the contribution of the individual physical processes underlying the SCG effect, focusing specifically on Raman processes and plasma formation in sapphire. For our experiments we use an amplified Ti:sapphire laser system producing nearly transform limited 60 fs pulses at 800 nm. Typical pulse energies for the experiments are 1--3 muJ/pulse. Using a new experimental technique, the spectrally resolved interferometric double pump, we study the contribution of non-instantaneous Raman effects. We see two distinct Raman contributions in sapphire which are much stronger than indicated in previous work. One Raman process has a period of approximately 185 fs and is related to an available optical phonon; the second Raman process has a period of 20 fs and is related to defect states caused by an oxygen vacancy in the sapphire crystal. Data from the same experiment show that the SCG light is not phase stable at low excitation energies, but that the phase stability is restored and saturates with increasing laser intensity. In a separate experiment we investigate the dynamics of plasma formation using a pump-probe technique. We observe that in sapphire both the formation and the decay of the plasma occur over time scales much longer than predicted by current theory. The plasma rise time is ˜225 fs, while the decay time is ˜150 ps; we also observe that these values do not depend on input pulse energy. In addition to these experiments, we perform a numerical integration of the extended (3 + 1) dimensional nonlinear Schrodinger equation, which models the propagation of a short laser pulse through a

  19. Optical temperature sensor utilizing birefringent crystals

    NASA Technical Reports Server (NTRS)

    Quick, William H. (Inventor); James, Kenneth A. (Inventor); Strahan, Virgil H. (Inventor)

    1980-01-01

    A temperature sensor comprising an optical transducer member having an array of birefringent crystals. The length and, accordingly, the sensitivity to temperature change of successive birefringent crystals varies according to a particular relationship. The transducer is interconnected with a fiber optic transmission and detecting system. Respective optical output signals that are transmitted from the birefringent crystals via the fiber optic transmission system are detected and decoded so as to correspond to digits of a numbering system, whereby an accurate digital representation of temperature can ultimately be provided.

  20. Two-Step Growth of (0001) ZnO Single-Crystal Layers on (0001) Sapphire Substrates by Halide Vapor Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Masuda, Rui; Togashi, Rie; Murakami, Hisashi; Kumagai, Yoshinao; Koukitu, Akinori

    2011-12-01

    The heteroepitaxial growth of (0001) ZnO on (0001) sapphire substrates by halide vapor phase epitaxy using a two-step growth procedure was investigated. X-ray diffraction analysis revealed that single-crystal (0001) ZnO layers on (0001) sapphire substrates were grown at 400 °C. High-temperature heteroepitaxy at 1000 °C on (0001) sapphire substrates was realized by two-step growth using the ZnO layer grown at 400 °C as a buffer layer. Two-dimensional layer growth at 1000 °C was realized on buffer layers thicker than 0.4 µm. Photoluminescence (PL) measurements performed at room temperature for the ZnO layer grown on the 0.4-µm-thick buffer layer showed a significant blueshift of near-band-edge emission (NBE). A thick buffer layer of 0.8 µm was found to be necessary for a successful two-step growth without a blueshift of NBE in the PL spectra, which is caused by a large compressive stress.

  1. Methodology of growing gigantic sapphire for GSLW project

    NASA Astrophysics Data System (ADS)

    Abgaryan, Artoush A.; Hartounian, Gomidas

    2005-09-01

    In our present world the Crystal Growth Technology does not have the necessary and sufficient conditions to manufacture large sizes; especially in the Sapphire Crystal world. We have a theoretical and methodological development for growing gigantic Sapphire Crystal Lenses. Our gigantic Sapphire Crystal Lenses have a unique optical characteristic which will be used in the Global System of Laser Weapons (GSLW); hence solving one of the crucial problems in the Relay Mirror System; where it captures the Laser beam from the earth surface, cleaning the beam in the Satellite and redirecting the laser energy to the precise desired target. Developed and solution for the temperature and heat-elasticity fields in growth systems are considered theoretical, in order to assess their effects on the optical symmetry of the growing crystal. The process is modeled using three-dimensional curvilinear coordinates to describe a closed, low-strain heat-elasticity system, with allowance made for the temperature variations of the thermal properties of the multilayer growth system, and nonlinear and unsteady-state process with arbitrary boundary conditions. The results presented as plots of the strain, stress, displacement, and temperature fields; demonstrate the potential of the method for designing new growth units and improving the existing ones and suggesting that crystals, in general, without frustration of optical symmetry can, in principle, be grown. In order to solve generalized problem for large optics. It is required to have super and correct mathematical computing calculations, and using basic fundamental laws of nature regarding optical symmetry in the crystal, and discovering the radical "new wave method" for crystal growth technology.

  2. Development of Sensors Using Evanescent Wave Interactions in Sapphire Optical Fibers

    SciTech Connect

    Michael W. Renfro; Eric H. Jordan

    2006-12-31

    The development of tunable diode laser absorption sensors for measurements in industrial boilers, both through direct absorption and evanescent wave absorption have been performed in the work presented here. These sensors use both direct and indirect absorption through the use of evanescent interactions within a coal firing combustion environment. For the direct absorption sensor, wavelength modulation absorption spectroscopy with second-harmonic detection was implemented within a physical probe designed to be placed with the flue stack of a power plant. Measurements were taken of carbon dioxide and water vapor concentration during operation at a local industrial facility. The design of this sensor probe overcomes problems of beam steering and permits a reference gas measurement. Extracted concentration data and design elements from the direct absorption measurements are presented. In addition, development of a sapphire fiber-based sensor using evanescent wave absorption along the outside of the fiber is presented. Evanescent absorption allows for the laser transmission to be maintained in the fiber at all times and may alleviate problems of background emission, beam steering, and especially scattering of the laser beam from solid particles experienced through free path direct absorption measurements in particulated flows. Laboratory measurements using evanescent fiber detection are presented.

  3. Tridimensional morphology and kinetics of etch pit on the {l_brace}0 0 0 1{r_brace} plane of sapphire crystal

    SciTech Connect

    Zhang Lunyong; Sun Jianfei; Zuo Hongbo; Yuan Zhiyong; Zhou Ji; Xing Dawei; Han Jiecai

    2012-08-15

    The tridimensional morphology and etching kinetics of the etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal ({alpha}-Al{sub 2}O{sub 3}) in molten KOH were studied experimentally. It was shown that the etch pit takes on tridimensional morphologies with triangular symmetry same as the symmetric property of the sapphire crystal. Pits like centric and eccentric triangular pyramid as well as hexagonal pyramid were observed, but the latter is less in density. In-depth analyses show the side walls of the etch pits belong to the {l_brace}1 1{sup Macron} 0 2{sup Macron }{r_brace} family, and the triangular pit contains edges full composed by Al{sup 3+} ions on the etching surface so it is more stable than the hexagonal pit since its edges on the etching surface contains Al{sup 2+} ions. The etch pits developed in a manner of kinematic wave by the step moving with constant speed, which is controlled by the chemical reaction with activation energy of 96.6 kJ/mol between Al{sub 2}O{sub 3} and KOH. - Graphical abstract: Schematic showing the atomic configuration of the predicted side walls of regular triangular pyramid shaped etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal. Highlights: Black-Right-Pointing-Pointer Observed the tridimensional morphology of etch pits. Black-Right-Pointing-Pointer Figured out the atomic configuration origin of the etch pits. Black-Right-Pointing-Pointer Quantitatively determined the etch rates of the etch pits.

  4. Ion Milling of Sapphire

    NASA Technical Reports Server (NTRS)

    Gregory, Don A.; Herren, Kenneth A.

    2004-01-01

    The ion milling of sapphire is a complicated operation due to several characteristics of the material itself. It is a relatively hard transparent nonconductive crystalline material that does not transfer heat nearly as well as metals that have been successfully ion milled in the past. This investigation involved designing an experimental arrangement, using existing ion milling equipment, as the precursor to figuring the surface of sapphire and other insulating optical materials. The experimental arrangement employs a laser probe beam to constantly monitor the stresses being induced in the material, as it is being ion milled. The goal is to determine if the technique proposed would indeed indicate the stress being induced in the material so that these stresses can be managed to prevent failure of the optic.

  5. Epitaxial growth, electrical and optical properties of a-plane InN on r-plane sapphire

    SciTech Connect

    Ajagunna, A. O.; Iliopoulos, E.; Tsiakatouras, G.; Tsagaraki, K.; Androulidaki, M.; Georgakilas, A.

    2010-01-15

    The heteroepitaxy of a-plane (1120) InN films on r-plane (1102) sapphire substrates, by nitrogen radio frequency plasma-assisted molecular beam epitaxy, has been investigated and compared to that of c-plane (0001) InN. The epitaxial growth of a-plane InN proceeded through the nucleation, growth, and coalescence of three-dimensional islands, resulting in surface roughness that increased monotonically with epilayer thickness. The full width at half maximum of (1120) x-ray diffraction rocking curves decreased significantly with increasing InN thickness, characteristic of structural improvement, and it reached the value of 24 arcmin for a 1 {mu}m thick film. Hall-effect measurements exhibited a similar dependence of electron concentration and mobility on thickness for both the a- and c-plane InN films. The analysis of the Hall-effect measurements, by considering the contribution of two conducting layers, indicates a similar accumulation of low mobility electrons with N{sub s}>10{sup 14} cm{sup -2} at the films' surface/interfacial region for both the a- and c-plane InN films. From optical transmittance measurements, the absorption edge of 0.768 eV was determined for the 1 {mu}m a-plane film, consistent with the expected Burstein-Moss effect. Photoluminescence spectra exhibited a lower energy peak at 0.631 eV, suggesting defect-related transitions.

  6. Eurolaser. High power excimer laser: Optical crystals

    NASA Astrophysics Data System (ADS)

    Gaenswein, Bernhard

    1987-09-01

    The crystals used in excimer lasers because of their excellent optical properties in the ultra violet spectrum are described. The crystals are fluorides of the alkaline earth metals magnesium, calcium and barium and the alkaline fluorides of lithium and sodium. It is possible to grow optical monocrystals of these compounds up to weights of 15 kg with a diameter of 180 mm. Some problems develop in growing crystals larger than this. To do so greater plants and improved automatic temperature monitoring and regulation are required. Special tools are needed for handling such large and heavy monocrystals. Understanding of the interaction between laser radiation and crystal must be improved upon in order to meet all the requirements to be placed on optical components in the future.

  7. Optical diagnostics of solution crystal growth

    NASA Technical Reports Server (NTRS)

    Kim, Yongkee; Reddy, B. R.; George, Tharayil G.; Lal, Ravindra B.

    1995-01-01

    Solution crystal growth monitoring of LAP/TGS crystals by various optical diagnostics systems, such as conventional and Mach-Zehnder (M-Z) interferometers, optical heterodyne technique, and ellipsometry, is under development. The study of the dynamics of the crystal growth process requires a detailed knowledge of crystal growth rate and the concentration gradient near growing crystals in aqueous solution. Crystal growth rate can be measured using conventional interferometry. Laser beam reflections from the crystal front as well as the back surface interfere with each other, and the fringe shift due to the growing crystal yields information about the growth rate. Our preliminary results indicate a growth rate of 6 A/sec for LAP crystals grown from solution. Single wavelength M-Z interferometry is in use to calculate the concentration gradient near the crystal. Preliminary investigation is in progress using an M-Z interferometer with 2 cm beam diameter to cover the front region of the growing crystal. In the optical heterodyne technique, phase difference between two rf signals (250 KHZ) is measured of which one is a reference signal, and the other growth signal, whose phase changes due to a change in path length as the material grows. From the phase difference the growth rate can also be calculated. Our preliminary results indicate a growth rate of 1.5 A/sec. the seed and solution temperatures were 26.46 C and 27.92 C respectively, and the solution was saturated at 29.0 C. an ellipsometer to measure the growth rate and interface layer is on order from JOBIN YVON, France. All these systems are arranged in such a manner that measurements can be made either sequentially or simultaneously. These techniques will be adapted for flight experiment.

  8. A Three-Dimensional Optical Photonic Crystal

    SciTech Connect

    Fleming, J.G.; Lin, S.

    1998-12-17

    The search for a photonic crystal to confine optical waves in all three dimensions (3D) has proven to be a formidable task. It evolves from an early theoretical suggestion [1,2], a brief skepticism [3-5] and triumph in developing the mm-wave [6-8] and infrared 3D photonic crystals [9]. Yet, the challenge remains, as the ultimate goal for optoelectronic applications is to realize a 3D crystal at X=1.5 pm communication wavelengths. Operating at visible and near infrared wavelengths, X=1-2 pm, a photonic crystal may enhance the spontaneous emission rate [1, 10] and give rise to a semiconductor lasers with a zero lasing threshold[11, 12]. Another important application is optically switching, routing and interconnecting light [13,14] with an ultrafast transmission speed of terabits per second. A photonic crystal may also serve as a platform for integrating an all-optical circuitry with multiple photonic components, such as waveguides and switches, built on one chip [15]. In this Letter, we report on the successful fabrication of a working 3D crystal operating at optical L The minimum feature size of the 3D structure is 180 nanometers. The 3D crystal is free from defects over the entire 6-inch silicon wafer and has an absolute photonic band gap centered at A.-1.6 pm. Our data provides the first conclusive evidence for the existence of a full 3D photonic band gap in optical A. This development will pave the way to tinier, cheaper, more effective waveguides, optical switches and lasers.

  9. Experimental demonstration of broadband femtosecond optical parametric amplification based on YCOB crystal at near critical wavelength degeneracy

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyang; Leng, Yuxin; Li, Yanyan; Li, Wenkai; Lu, Xiaoming; Xu, Yi; Li, Ruxin

    2016-07-01

    Broadband optical parametric amplification (OPA) in the near-infrared region (1.3-1.8 μm) is demonstrated in YCOB crystal pumped by 1 kHz Ti:sapphire based femtosecond laser at near critical wavelength degeneracy phase matching condition at first time. The gain bandwidth is closed to BIBO or BBO crystal OPA gain bandwidth. The energy obtained with 3.5 mm-thick YCOB reached 20 μJ with RMS 1.9%. After second harmonic generation, 17.6 fs pulse is obtained, and the pulse compressibility is demonstrated.

  10. Silicon-on-sapphire fiber optic transceiver technology for space applications

    NASA Astrophysics Data System (ADS)

    Kuznia, C. P.; Ahadian, J. F.; Pommer, R. J.; Hagan, R.

    2007-09-01

    We present Single Event Upset (SEU) testing of a parallel fiber optic transceiver designed for communicating data using commercial Fibre Channel and GbE protocols at data rates up to 2.5 Gbps per channel (on eight parallel channels). This transceiver was developed for aircraft applications, such as the Joint Strike Fighter (JSF), Raptor and F/A-18 aircraft, that deploy fiber optic networks using multi-mode fiber operating at 850 nm wavelength. However, this transceiver may also have applications in space environments. This paper describes the underlying transceiver component technology, which utilizes complementary metal-oxide semiconductor (CMOS) silicon-onsapphire circuitry and GaAs VCSEL and PIN devices. We also present results of SEU testing of this transceiver using heavy ions at Brookhaven National Labs.

  11. Optical analysis of crystal growth

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Passeur, Andrea; Harper, Sabrina

    1994-01-01

    Processing and data reduction of holographic images from Spacelab presents some interesting challenges in determining the effects of microgravity on crystal growth processes. Evaluation of several processing techniques, including the Computerized Holographic Image Processing System and the image processing software ITEX150, will provide fundamental information for holographic analysis of the space flight data.

  12. Erbium doped tellurite photonic crystal optical fiber

    NASA Astrophysics Data System (ADS)

    Osorio, Sergio P.; Fernandez, Enver; Rodriguez, Eugenio; Cesar, Carlos L.; Barbosa, Luiz C.

    2005-04-01

    In this work we present the fabrication of tellurite glass photonic crystal fiber doped with a very large erbium concentration. Tellurite glasses are important hosts for rare earth ions due to its very high solubility, which allows up to 10,000 ppm Er3+ concentrations. The photonic crystal optical fibers and tellurite glasses can be, therefore, combined in an efficient way to produce doped fibers for large bandwidth optical amplifiers. The preform was made of a 10 mm external diameter tellurite tube filled with an array of non-periodic tellurite capillaries and an erbium-doped telluride rod that constitute the fiber core. The preform was drawn in a Heathway Drawing Tower, producing fibers with diameters between 120 - 140 μm. We show optical microscope photography of the fiber"s transverse section. The ASE spectra obtained with a spectra analyzer show a red shift as the length of the optical fiber increases.

  13. Structural and optical properties of AgAlTe{sub 2} layers grown on sapphire substrates by closed space sublimation method

    SciTech Connect

    Uruno, A. Usui, A.; Kobayashi, M.

    2014-11-14

    AgAlTe{sub 2} layers were grown on a- and c-plane sapphire substrates using a closed space sublimation method. Grown layers were confirmed to be single phase layers of AgAlTe{sub 2} by X-ray diffraction. AgAlTe{sub 2} layers were grown to have a strong preference for the (112) orientation on both kinds of substrates. The variation in the orientation of grown layers was analyzed in detail using the X-ray diffraction pole figure measurement, which revealed that the AgAlTe{sub 2} had a preferential epitaxial relationship with the c-plane sapphire substrate. The atomic arrangement between the (112) AgAlTe{sub 2} layer and sapphire substrates was compared. It was considered that the high order of the lattice arrangement symmetry probably effectively accommodated the lattice mismatch. The optical properties of the grown layer were also evaluated by transmittance measurements. The bandgap energy was found to be around 2.3 eV, which was in agreement with the theoretical bandgap energy of AgAlTe{sub 2}.

  14. Optical monitoring of protein crystal growth

    NASA Technical Reports Server (NTRS)

    Choudry, A.

    1988-01-01

    The possibility of using various optical techniques for detecting the onset of nucleation in protein crystal growth was investigated. Direct microscopy, general metrologic techniques, light scattering, ultraviolet absorption, and interferometry are addressed along with techniques for determining pH value. The necessity for collecting basic data on the optical properties of the growth solution as a prerequisite to the evaluation of monitoring techniques is pointed out.

  15. Novelty filtered optical correlator using photorefractive crystal

    NASA Technical Reports Server (NTRS)

    Liu, Duncan T. H.; Chao, Tien-Hsin; Cheng, Li-Jen

    1992-01-01

    We demonstrate a new optical correlator in which the correlation peak intensity is increased when the matched input object is moving. The basic configuration of the correlator is the same as a VanderLugt optical correlator consisting of a photorefractive crystal. The principal of this new correlator is based on the dynamic grating erasure property of photorefractive materials. The detail of this principle is described.

  16. Optical modeling of liquid crystal biosensors

    NASA Astrophysics Data System (ADS)

    Hwang, Dae Kun; Rey, Alejandro D.

    2006-11-01

    Optical simulations of a liquid crystal biosensor device are performed using an integrated optical/textural model based on the equations of nematodynamics and two optical methods: the Berreman optical matrix method [J. Opt. Soc. Am. 62, 502 (1972)] and the discretization of the Maxwell equations based on the finite difference time domain (FDTD) method. Testing the two optical methods with liquid crystal films of different degrees of orientational heterogeneities demonstrates that only the FDTD method is suitable to model this device. Basic substrate-induced texturing process due to protein adsorption gives rise to an orientation correlation function that is nearly linear with the transmitted light intensity, providing a basis to calibrate the device. The sensitivity of transmitted light to film thickness, protein surface coverage, and wavelength is established. A crossover incident light wavelength close to λco≈500nm is found, such that when λ >λco thinner films are more sensitive to the amount of protein surface coverage, while for λ <λco the reverse holds. In addition it is found that for all wavelengths the sensitivity increases with the amount of protein coverage. The integrated device model based on FDTD optical simulations in conjunction with the Landau-de Gennes nematodynamics model provides a rational basis for further progress in liquid crystal biosensor devices.

  17. Optical crystal temperature gauge with fiber optic connections

    SciTech Connect

    Sharma, M.M.

    1982-07-01

    An optical temperature gauge uses a semiconductor crystal with a band-edge shift property which is temperature dependent. An external narrow band light source provides optical excitation through a optical fiber and light energy thus passed through the crystal is conveyed by a second optical fiber to a light-to-electric transducers at an external location. The crystal can be located in cryogenic or other systems, to provide remote read-out. The light wavelength is varied (scanned) in a repetitive pattern in source with the instantaneous wavelength passing over the band-edge wavelength during each cycle of the scan. The timing of the crossover is related to the temperature of the crystal by electronic means. Several alternative elements of instrumentation are disclosed. A variation in the basic measurement apparatus is also disclosed, in which the band gap voltage of a light source such as a laser diode is evaluated at the time of band-edge crossover in the crystal and converted to a temperature value. Official Gazette of the U.S. Patent and Trademark Office

  18. Single-crystal sapphire endosseous dental implant loaded with functional stress--clinical and histological evaluation of peri-implant tissues.

    PubMed

    Hashimoto, M; Akagawa, Y; Nikai, H; Tsuru, H

    1988-01-01

    Peri-implant tissues of the single-crystal sapphire implant connected with neighbouring teeth by a metal bridge-work were examined clinically, radiographically, and histologically in ten monkeys. Professional tooth cleaning was performed during the study. At 3-12 months after insertion, most of the implants were firmly connected to the surrounding tissues and peri-implant gingiva was regarded as healthy, based on various periodontal parameter scores. Destructive changes of the peri-implant bone were not found radiographically. Histologically, peri-implant gingiva was revealed to show similar structure to that of the gingiva around natural teeth. Direct bone-implant interface was observed at 3 months after insertion, while a thin loose fibrous connective tissue layer was present between bone and implant at 6 and 12 months. Such different interrelationship between bone and implant might be attributable to the difference in distribution of functional stress.

  19. Experimental observation of optical precursors in optically pumped crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Zong-Quan; Li, Chuan-Feng; Guo, Guang-Can

    2013-04-01

    We experimentally observed optical precursors in optically pumped crystals using polarization-based interference. By switching the user-programmable medium among the fast light, slow light, and no-dispersion regimes, we observed an unchanged polarization state for the wave fronts. The robust polarization-encoded information carried by wave fronts suggests that precursors are the preferred carriers for both quantum and classical information in communication networks.

  20. Optical solitons in liquid crystals

    SciTech Connect

    Yung, Y.S.; Lam, L.; Los Alamos National Lab., NM )

    1989-01-01

    In this paper, we will discuss theoretically the possible existence of optical solitons in the isotropic liquid and in the nematic phase. For the same compound, when heated, the nematic phase will go through a first order transition at temperature T{sub c} to the isotropic liquid phase. As temperature increases from below T{sub c}, the orientation order parameter, Q, decreases, drops to zero abruptly at T{sub c} and remains zero for T > T{sub c}. 10 refs., 1 fig.

  1. Thermal characteristics of sapphire contact probe delivery systems for laser angioplasty.

    PubMed

    Ashley, S; Brooks, S G; Gehani, A A; Kester, R C; Rees, M R

    1990-01-01

    Contact probes made from synthetic sapphire crystal, designed for general laser surgery, are currently being evaluated for use in laser angioplasty. Their mode of action and safety in the context of arterial recanalisation is unknown, particularly with respect to the degree of probe and catheter heating. Infrared thermal imaging was used to investigate the surface temperature rise of various rounded sapphire probes during emission of continuous wave Nd-YAG (1,064 nm) laser energy. Catheter safety was addressed by analyzing the temperature of the metal interface between the optical fiber and sapphire, as well as the catheter proximal to this junction. Transmission of Nd-YAG energy through each probe was also measured. Five rounded probes of 1.8-3.0 mm diameter (three supplied by Surgical Laser Technologies [SLT], two by Living Technology [LT]), along with their respective optical catheters, were compared. There was a large temperature gradient between the front and rim of the probes. The maximum surface temperature rise of the sapphire (at 20 W, 5-second exposure) was 314-339 degrees C (SLT) and 90-108 degrees C (LT) [P less than 0.001, 3-way ANOVA]. The reason for this difference may be related to "crazing" of the front surface of the SLT sapphires. At all energy levels sapphire temperatures were considerably lower than attained by metal laser thermal angioplasty probes. Forward transmission was slightly higher in the SLT probes (75-85%) than the LT sapphires (54-69%). With fiber perfusion at 2 ml/minute, a minor degree of heating of the metal sapphire holders was recorded (maximum rise 35 degrees C), but heating of the catheter proximal to this was negligible. Therefore, it would appear that the risk of tip detachment or arterial injury due to heating of the connecting metal interface is extremely low. Without perfusion, however, there was a greater degree of interface heating in the LT delivery system suggestive of more laser backscattering by these sapphires

  2. Thermal characteristics of sapphire contact probe delivery systems for laser angioplasty.

    PubMed

    Ashley, S; Brooks, S G; Gehani, A A; Kester, R C; Rees, M R

    1990-01-01

    Contact probes made from synthetic sapphire crystal, designed for general laser surgery, are currently being evaluated for use in laser angioplasty. Their mode of action and safety in the context of arterial recanalisation is unknown, particularly with respect to the degree of probe and catheter heating. Infrared thermal imaging was used to investigate the surface temperature rise of various rounded sapphire probes during emission of continuous wave Nd-YAG (1,064 nm) laser energy. Catheter safety was addressed by analyzing the temperature of the metal interface between the optical fiber and sapphire, as well as the catheter proximal to this junction. Transmission of Nd-YAG energy through each probe was also measured. Five rounded probes of 1.8-3.0 mm diameter (three supplied by Surgical Laser Technologies [SLT], two by Living Technology [LT]), along with their respective optical catheters, were compared. There was a large temperature gradient between the front and rim of the probes. The maximum surface temperature rise of the sapphire (at 20 W, 5-second exposure) was 314-339 degrees C (SLT) and 90-108 degrees C (LT) [P less than 0.001, 3-way ANOVA]. The reason for this difference may be related to "crazing" of the front surface of the SLT sapphires. At all energy levels sapphire temperatures were considerably lower than attained by metal laser thermal angioplasty probes. Forward transmission was slightly higher in the SLT probes (75-85%) than the LT sapphires (54-69%). With fiber perfusion at 2 ml/minute, a minor degree of heating of the metal sapphire holders was recorded (maximum rise 35 degrees C), but heating of the catheter proximal to this was negligible. Therefore, it would appear that the risk of tip detachment or arterial injury due to heating of the connecting metal interface is extremely low. Without perfusion, however, there was a greater degree of interface heating in the LT delivery system suggestive of more laser backscattering by these sapphires

  3. Optical amplification enhancement in photonic crystals

    SciTech Connect

    Sapienza, R.; Leonetti, M.; Froufe-Perez, L. S.; Galisteo-Lopez, J. F.; Lopez, C.; Conti, C.

    2011-02-15

    Improving and controlling the efficiency of a gain medium is one of the most challenging problems of laser research. By measuring the gain length in an opal-based photonic crystal doped with laser dye, we demonstrate that optical amplification is more than twenty-fold enhanced along the {Gamma}-K symmetry directions of the face-centered-cubic photonic crystal. These results are theoretically explained by directional variations of the density of states, providing a quantitative connection between density of the states and light amplification.

  4. Amplifying magneto-optical photonic crystal

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.

    2010-08-01

    We modeled transmission and Faraday rotation characteristics of Er-doped all-garnet [Bi3Fe5O12/Gd3Ga5O12]m photonic crystals in view of their application in C-band magneto-optical amplifiers. It is found that 48 layered 11.4 μm thick crystal at λ =1532 nm provides 45° Faraday rotation and transmission as high as 85% being pumped with 100 mW/980 nm solid state laser diode.

  5. Integrated diamond sapphire laser

    NASA Astrophysics Data System (ADS)

    Fork, Richard L.; Walker, Wesley W.; Laycock, Rustin L.; Green, Jason J. A.; Cole, Spencer T.

    2003-10-01

    We use analytic expressions and simulations to examine a model laser gain element formed by integrating diamond and a solid state laser material, such as, Ti:sapphire. The gain element is designed to provide in a single composite structure the thermal management capabilities of diamond and the optical amplification of the laser material. The model results indicate low temperature and a specific radial dependence of the heat transfer coefficient at the material interfaces are needed to access the highest average powers and highest quality optical fields. We outline paths designed to increase average output power of a lowest order mode laser oscillator based on these gain elements to megawatt levels. The long term goal is economically viable solar power delivered safely from space. The short term goal is a design strategy that will facilitate "proof of principle" demonstrations using currently accessible optical pump and thermal management capabilities.

  6. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    SciTech Connect

    Soltani, A. Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C.; Charrier, J.; Mattalah, M.; Barkad, H. A.; Mortet, V.

    2014-04-28

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  7. Optical Restoration of Lead Fluoride Crystals

    SciTech Connect

    Spilker, A.; Cole, P. L.; Forest, T. A.; Mestari, M.; Naeem, S.; LeBaron, N.; Bertin, P.; Camacho, C. Munoz; Roche, J.

    2009-03-10

    Due to its relatively high resistance to high radiation, lead fluoride (PbF{sub 2}) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF{sub 2} crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF{sub 2} samples with 1.1 and 1.3 MeV gammas from {sup 60}Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410-450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF{sub 2} samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching.

  8. Luminescent Magneto-Optical Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Khartsev, S. I.

    2012-03-01

    We compare luminescent properties of several Er-doped garnet films as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals: La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, Bi3Fe5O12, and Bi2.97Er0.03Fe4Al0.5Ga0.5O12. Er substituents on the dodecahedral lattice sites do not decrease giant Faraday rotation in Bi3Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching 6 ms in Gd2.9Er0.1Ga5O12. The first luminescent one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystal was composed from diamagnetic Sm3Ga5O12 and MO-active Bi2.97Er0.03Al0.5Ga0.5O12 garnet layers by rf-magnetron sputtering on Gd3Ga5O12(111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure Bi3Fe5O12. Photonic crystals owned a record high magneto-optical quality and a latching type (magnetic remnant) Faraday rotation (FR). At the resonance wavelength 775 nm, specific FR θF = - 14.1 deg/μm and MO-quality factor Q = 99.3 deg represent the highest MO performance achieved so far. Long-lived near-IR luminescence in Er substituted gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

  9. Characterization of single crystal films of molybdenum (011) grown by molecular beam epitaxy on sapphire (112¯0) and studied by low-energy electron microscopy

    NASA Astrophysics Data System (ADS)

    Świȩch, W.; Mundschau, M.; Flynn, C. P.

    1999-08-01

    Films of molybdenum grown on the (112¯0) plane of sapphire (Al 2O 3) are characterized using low-energy microscopy and low-energy electron diffraction. Stress fields observed on the Mo surface originate at dislocations and at miscut steps of the buried molybdenum-alumina vicinal interface. As-grown films contain small-angle grain boundaries. These are largely eliminated upon heating to 1700 K as edge dislocations that form the boundaries become extremely mobile. Edge dislocations attract and annihilate one another, and the small-angle grain boundaries disappear. Mobility of edge dislocations is correlated with rapid diffusion of carbon, which apparently pins dislocations up to temperatures that allow diffusion of carbon from dislocations into the bulk. The main contaminants of the Mo surface are carbon, oxygen and carbon monoxide. The most stable impurities are carbides that persist to 1700 K. Oxygen promotes bunching of monatomic steps into groups of two, three and four. Electron beams dissociate CO with energy less than 1 eV and deposit residues of carbon. Fairly ideal single crystal films of Mo produced by annealing exhibit monatomic surface step and terrace structure, and a minimum of dislocations. The quality of surfaces on these films exceeds that of typical single crystal bulk samples and is well suited for fundamental studies in surface science.

  10. Complete characterization of a self-mode-locked ti:sapphire laser in the vicinity of zero group-delay dispersion by frequency-resolved optical gating.

    PubMed

    Dudley, J M; Boussen, S M; Cameron, D M; Harvey, J D

    1999-05-20

    The intensity and the phase of ultrashort pulses from a self-mode-locked Ti:sapphire laser operating in the vicinity of zero group-delay dispersion (GDD) have been completely characterized by the technique of frequency-resolved optical gating (FROG). For small values of negative GDD, the appearance of a dispersive wave in the pulse spectrum is manifested in the measured FROG trace, and pulse retrieval directly shows its association with a broad leading-edge pedestal. For positive GDD, we confirm previous experimental observations of picosecond pulses with large positive chirp and report a new operating regime in which the output pulses are of picosecond duration but are intensity modulated at 20 THz. The physical origin of this modulation is discussed by analogy with similar effects observed during pulse propagation in optical fibers, and the experimental results are compared with a model of intracavity four-wave mixing about the cavity zero GDD wavelength. PMID:18319926

  11. Optics in Microstructured and Photonic Crystal Fibers

    NASA Astrophysics Data System (ADS)

    Knight, J. C.

    2008-10-01

    The development of optical fibers with two-dimensional patterns of air holes running down their length has reinvigorated research in the field of fiber optics. It has greatly—and fundamentally—broadened the range of specialty optical fibers, by demonstrating that optical fibers can be more "special" than previously thought. Fibers with air cores have made it possible to deliver energetic femtosecond-scale optical pulses, transform limited, as solitons, using single-mode fiber. Other fibers with anomalous dispersion at visible wavelengths have spawned a new generation of single-mode optical supercontinuum sources, spanning visible and near-infrared wavelengths and based on compact pump sources. A third example is in the field of fiber lasers, where the use of photonic crystal fiber concepts has led to a new hybrid laser technology, in which the very high numerical aperture available sing air holes have enabled fibers so short they are more naturally held straight than bent. This paper describes some of the basic physics and technology behind these developments, illustrated with some of the impressive demonstrations of the past 18 months.

  12. Rate of F center formation in sapphire under low-energy low-fluence Ar+ irradiation

    NASA Astrophysics Data System (ADS)

    Epie, E. N.; Wijesundera, D. N.; Tilakaratne, B. P.; Chen, Q. Y.; Chu, W. K.

    2016-03-01

    Ionoluminescence, optical absorption spectroscopy and Rutherford backscattering spectrometry channelling (RBS-C) have been used to study the rate of F center formation with fluence in 170 keV Ar+ irradiated single crystals of α-Al2O3 (sapphire) at room temperature. Implantation fluences range between 1013 cm-2 and 5 ×1014 cm-2. F center density (NF) has been found to display an initial rapid linear increase with Ar+ fluence followed by saturation to a maximum value of 1.74 ×1015 cm-2. Experimental results show a 1-1 correlation between radiation damage in the oxygen sublattice and F center density. This suggest F center kinetics in sapphire under low-energy low-fluence Ar irradiation is a direct consequence of dynamic competition between oxygen defect creation and recombination. An attempt has also been made to extend this discussion to F center kinetics in sapphire under swift heavy ion irradiation.

  13. Liquid Crystal Television For Optical Correlation

    NASA Astrophysics Data System (ADS)

    Perng, Wen-Sheng; Cheng, Yih-Shyang; Chang, Ming-Wen

    1987-08-01

    In this paper, we present a newly developed hybrid multi-channel real-time pattern recognition system. Two modified commercial liquid crystal televisions are applied as a real-time incoherent to coherent image transducer and a device to produce converging wavelets with different focal positions. Taking advantages of the cross-grating nature of the LCTV screen, a multi-channel correlator becomes possible. This hybrid system has both the high processing speed of an optical system and the flexibility of an electronic system.

  14. Photonic crystal electro-optical switching cell

    NASA Astrophysics Data System (ADS)

    Lima, A. Wirth; Sombra, A. S. B.

    2012-06-01

    We investigated the physical mechanism of a photonic crystal (PhC) switching cell based on an optical directional coupler (ODC). This ODC is driven by a low power external electrical command signal, inserted in the central coupling region, which causes the changes in the refractive index. The switching process is based on the change of the bar state to the cross state owing to the external command signal. In our simulations we used the following methods: Plane Wave Expansion by MPB (MIT Photonic-Bands), Finite-Difference Time-Domain by MEEP (MIT Electromagnetic Equation Propagation), Finite Element by COMSOL Multiphysics and our own Binary Propagation Method.

  15. Wide Angle Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Wang, Xing-Hua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John J.; Miranda, Felix A.; McManamon, Paul F.

    2004-01-01

    Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.

  16. Optical trapping apparatus, methods and applications using photonic crystal resonators

    SciTech Connect

    Erickson, David; Chen, Yih-Fan

    2015-06-16

    A plurality of photonic crystal resonator optical trapping apparatuses and a plurality optical trapping methods using the plurality of photonic crystal resonator optical trapping apparatuses include located and formed over a substrate a photonic waveguide that is coupled (i.e., either separately coupled or integrally coupled) with a photonic crystal resonator. In a particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a monocrystalline silicon (or other) photonic material absent any chemical functionalization. In another particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a silicon nitride material which when actuating the photonic crystal resonator optical trapping apparatus with a 1064 nanometer resonant photonic radiation wavelength (or other resonant photonic radiation wavelength in a range from about 700 to about 1200 nanometers) provides no appreciable heating of an aqueous sample fluid that is analyzed by the photonic crystal resonator optical trapping apparatus.

  17. Optical Investigation of Nanoconfined Crystal Growth

    NASA Astrophysics Data System (ADS)

    Kohler, F.; Dysthe, D. K.

    2015-12-01

    Crystals growing in a confined space exert forces on their surroundings. This crystallization force causes deformation of solids and is therefore particularly relevant for the comprehension of geological processes such as replacement and weathering [1]. In addition, these forces are relevant for the understanding of damages in porous building materials caused by crystallization, which is of great economical importance and fundamental for methods that can help to preserve our cultural heritage [2,3]. However, the exact behavior of the growth and the dissolution process in close contact to an interface are still not known in detail. The crystallization, the dissolution and the transport of material is mediated by a nanoconfined water film. We observe brittle NaClO3 crystals growing against a glass surface by optical methods such as reflective interference contrast microscopy (RICM) [4]. In order to carefully control the supersaturation of the fluid close to the crystal interface, a temperature regulated microfluidic system is used (fig. A). The interference based precision of RICM enables to resolve distance variations down to the sub nanometer range without any unwanted disturbances by the measuring method. The combination of RICM with a sensitive camera allows us to observe phenomena such as periodic, wavelike growth of atomic layers. These waves are particularly obvious when observing the difference between two consecutive images (fig. B). In contradiction to some theoretical results, which predict a smooth interface, some recent experiments have shown that the nanoconfined growth surfaces are rough. In combination with theoretical studies and Kinetic Monte Carlo simulations we aim at providing more realistic descriptions of surface energies and energy barriers which are able to explain the discrepancies between experiments and current theory. References:[1] Maliva, Diagenetic replacement controlled by force of crystallization, Geology, August (1988), v. 16 [2] G

  18. Measuring single-shot, picosecond optical damage threshold in Ge, Si, and sapphire with a 5.1-μm laser

    DOE PAGES

    Agustsson, R.; Pogorelsky, I.; Arab, E.; Murokh, A.; O"Shea, B.; Ovodenko, A.; Rosenzweig, J.; Solovyov, V.; Tilton, R.

    2015-11-18

    Optical photonic structures driven by picosecond, GW-class lasers are emerging as promising novel sources of electron beams and high quality X-rays. Due to quadratic dependence on wavelength of the laser ponderomotive potential, the performance of such sources scales very favorably towards longer drive laser wavelengths. However, to take full advantage of photonic structures at mid-IR spectral region, it is important to determine optical breakdown limits of common optical materials. To this end, an experimental study was carried out at a wavelength of 5 µm, using a frequency-doubled CO2 laser source, with 5 ps pulse length. Single-shot optical breakdowns were detectedmore » and characterized at different laser intensities, and damage threshold values of 0.2, 0.3, and 7.0 J/cm2, were established for Ge, Si, and sapphire, respectively. As a result, the measured damage threshold values were stable and repeatable within individual data sets, and across varying experimental conditions.« less

  19. Measuring single-shot, picosecond optical damage threshold in Ge, Si, and sapphire with a 5.1-μm laser

    SciTech Connect

    Agustsson, R.; Pogorelsky, I.; Arab, E.; Murokh, A.; O"Shea, B.; Ovodenko, A.; Rosenzweig, J.; Solovyov, V.; Tilton, R.

    2015-11-18

    Optical photonic structures driven by picosecond, GW-class lasers are emerging as promising novel sources of electron beams and high quality X-rays. Due to quadratic dependence on wavelength of the laser ponderomotive potential, the performance of such sources scales very favorably towards longer drive laser wavelengths. However, to take full advantage of photonic structures at mid-IR spectral region, it is important to determine optical breakdown limits of common optical materials. To this end, an experimental study was carried out at a wavelength of 5 µm, using a frequency-doubled CO2 laser source, with 5 ps pulse length. Single-shot optical breakdowns were detected and characterized at different laser intensities, and damage threshold values of 0.2, 0.3, and 7.0 J/cm2, were established for Ge, Si, and sapphire, respectively. As a result, the measured damage threshold values were stable and repeatable within individual data sets, and across varying experimental conditions.

  20. The effect of nucleation layer thickness on the structural evolution and crystal quality of bulk GaN grown by a two-step process on cone-patterned sapphire substrate

    NASA Astrophysics Data System (ADS)

    Shang, Lin; Zhai, Guangmei; Mei, Fuhong; Jia, Wei; Yu, Chunyan; Liu, Xuguang; Xu, Bingshe

    2016-05-01

    The role of nucleation layer thickness on the GaN crystal quality grown on cone-patterned sapphire substrate (PSS) was explored. The morphologies of epitaxial GaN at different growth stages were investigated by a series of growth interruption in detail. After 10- and 15-min three-dimensional growth, the nucleation sites are very important for the bulk GaN crystal quality. They have a close relationship with the nucleation layer thickness, as confirmed through the scanning electron microscope (SEM) analysis. Nucleation sites formed mainly on patterns are bad for bulk GaN crystal quality and nucleation sites formed mainly in the trenches of PSS mounds are good for bulk GaN crystal quality, as proved by X-ray diffraction analysis. Nucleation layer thickness can effectively control the nucleation sites and thus determine the crystal quality of bulk GaN.

  1. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, S.D.; Marshall, K.L.; Cerqua, K.A.

    1991-10-08

    Composite optical devices are disclosed using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T[sub g]) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device. 7 figures.

  2. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, Stephen D.; Marshall, Kenneth L.; Cerqua, Kathleen A.

    1991-01-01

    Composite optical devices using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T.sub.g) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device.

  3. Planar optics with patterned chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-01

    Reflective metasurfaces based on metallic and dielectric nanoscatterers have attracted interest owing to their ability to control the phase of light. However, because such nanoscatterers require subwavelength features, the fabrication of elements that operate in the visible range is challenging. Here, we show that chiral liquid crystals with a self-organized helical structure enable metasurface-like, non-specular reflection in the visible region. The phase of light that is Bragg-reflected off the helical structure can be controlled over 0-2π depending on the spatial phase of the helical structure; thus planar elements with arbitrary reflected wavefronts can be created via orientation control. The circular polarization selectivity and external field tunability of Bragg reflection open a wide variety of potential applications for this family of functional devices, from optical isolators to wearable displays.

  4. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope.

  5. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope. PMID:19844566

  6. Photonic detection and characterization of DNA using sapphire microspheres

    NASA Astrophysics Data System (ADS)

    Murib, Mohammed Sharif; Yeap, Weng-Siang; Martens, Daan; Bienstman, Peter; De Ceuninck, Ward; van Grinsven, Bart; Schöning, Michael J.; Michiels, Luc; Haenen, Ken; Ameloot, Marcel; Serpengüzel, Ali; Wagner, Patrick

    2014-09-01

    A microcavity-based deoxyribonucleic acid (DNA) optical biosensor is demonstrated for the first time using synthetic sapphire for the optical cavity. Transmitted and elastic scattering intensity at 1510 nm are analyzed from a sapphire microsphere (radius 500 μm, refractive index 1.77) on an optical fiber half coupler. The 0.43 nm angular mode spacing of the resonances correlates well with the optical size of the sapphire sphere. Probe DNA consisting of a 36-mer fragment was covalently immobilized on a sapphire microsphere and hybridized with a 29-mer target DNA. Whispering gallery modes (WGMs) were monitored before the sapphire was functionalized with DNA and after it was functionalized with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The shift in WGMs from the surface modification with DNA was measured and correlated well with the estimated thickness of the add-on DNA layer. It is shown that ssDNA is more uniformly oriented on the sapphire surface than dsDNA. In addition, it is shown that functionalization of the sapphire spherical surface with DNA does not affect the quality factor (Q≈104) of the sapphire microspheres. The use of sapphire is especially interesting because this material is chemically resilient, biocompatible, and widely used for medical implants.

  7. Fabrication of fully undercut ZnO-based photonic crystal membranes with 3D optical confinement

    NASA Astrophysics Data System (ADS)

    Hoffmann, Sandro Phil; Albert, Maximilian; Meier, Cedrik

    2016-09-01

    For studying nonlinear photonics, a highly controllable emission of photons with specific properties is essential. Two-dimensional photonic crystals (PhCs) have proven to be an excellent candidate for manipulating photon emission due to resonator-based effects. Additionally, zinc oxide (ZnO) has high susceptibility coefficients and therefore shows pronounced nonlinear effects. However, in order to fabricate such a cavity, a fully undercut ZnO membrane is required, which is a challenging problem due to poor selectivity of the known etching chemistry for typical substrates such as sapphire or ZnO. The aim of this paper is to demonstrate and characterize fully undercut photonic crystal membranes based on a thin ZnO film sandwiched between two layers of silicon dioxide (SiO2) on silicon substrates, from the initial growth of the heterostructure throughout the entire fabrication process. This process leads to a fully undercut ZnO-based membrane with adjustable optical confinement in all three dimensions. Finally, photonic resonances within the tailored photonic band gap are achieved due to optimized PhC-design (in-plane) and total internal reflection in the z-direction. The presented approach enables a variety of photon based resonator structures in the UV regime for studying nonlinear effects, including photon-exciton coupling and all-optical switching.

  8. Effect of sapphire substrate orientations on the microstructural, optical and NO2 gas sensing properties of Zn(1-x)CdxO thin films synthesized by sol gel spin-coating method

    NASA Astrophysics Data System (ADS)

    Boukadhaba, M. A.; Chebil, W.; Fouzri, A.; Sallet, V.; Lusson, A.; Amiri, G.; Vilar, C.; Oumezzine, M.

    2016-06-01

    A simple and cost-effective sol-gel technique was employed to elaborate ZnO and Zn(1-x)CdxO thin films deposit by spin coating onto the c- and r-plane sapphire substrates. The deposited films were characterized for their structural, morphological and optical properties using high resolution X ray diffraction (HRXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) as function of Cd incorporation and employed substrate. Higher Cd incorporation (4.5%) is obtained for ZnCdO layer deposited on r-plane sapphire, which is confirmed by the greatest energy shift (110 meV) to lower energy measured by low temperature photoluminescence. X-ray diffraction study revealed that all films are polycrystalline with a hexagonal wurtzite structure. A preferred orientation along [001] and [110] direction is obtained respectively for layer deposited on c- and r-plane sapphire. However, the (002) and (110) XRD layers peak were shifted towards the lower 2θ values after Cd incorporation showing a slight variation of cell parameters. SEM and AFM image show no very significant variation in the morphology of the layers depending on the substrate orientation and Cd content incorporated. A mixture of large and small hexagonal grains are obtained which are more pronounced for ZnCdO deposited on r-plane sapphire and their agglomeration leaves more empty space in films. The gas sensing performances were tested in NO2 containing air for different operating temperatures as function of Cd incorporation and sapphire substrate orientation. The experimental result exhibited that ZnCdO sensors deposited on r-plane sapphire shows a more better gas response with fast response and recovery time at moderate operating temperatures as Cd contend increase.

  9. Electro-optic phase modulation by polymer dispersed liquid crystals

    NASA Astrophysics Data System (ADS)

    Vicari, L.

    1997-05-01

    We present a mathematical model to describe the optical phase shift induced by polymer dispersed liquid crystals (PDLCs) on light impinging transversely on the sample. PDLCs are dispersions of liquid crystal microdroplets in a polymeric binder. Droplets appear as optically uniaxial spheres randomly oriented so that the material is optically isotropic. The application of an external electric field results in a reorientation of the liquid crystal and therefore in an electrically controllable optical uniaxicity of the material. The model is discussed by comparison with experimental data and with previous theory [F. Basile, F. Bloisi, L. Vicari, and F. Simoni, Phys. Rev. E 48, 432 (1993)].

  10. Optical defect modes in chiral liquid crystals

    SciTech Connect

    Belyakov, V. A.; Semenov, S. V.

    2011-04-15

    An analytic approach to the theory of optical defect modes in chiral liquid crystals (CLCs) is developed. The analytic study is facilitated by the choice of the problem parameters. Specifically, an isotropic layer (with the dielectric susceptibility equal to the average CLC dielectric susceptibility) sandwiched between two CLC layers is studied. The chosen model allows eliminating the polarization mixing and reducing the corresponding equations to the equations for light of diffracting polarization only. The dispersion equation relating the defect mode (DM) frequency to the isotropic layer thickness and an analytic expression for the field distribution in the DM structure are obtained and the corresponding dependences are plotted for some values of the DM structure parameters. Analytic expressions for the transmission and reflection coefficients of the DM structure (CLC-defect layer-CLC) are presented and analyzed for nonabsorbing, absorbing, and amplifying CLCs. The anomalously strong light absorption effect at the DM frequency is revealed. The limit case of infinitely thick CLC layers is considered in detail. It is shown that for distributed feedback lasing in a defect structure, adjusting the lasing frequency to the DM frequency results in a significant decrease in the lasing threshold. The DM dispersion equations are solved numerically for typical values of the relevant parameters. Our approach helps clarify the physics of the optical DMs in CLCs and completely agrees with the corresponding results of the previous numerical investigations.

  11. Elasto-optic effect anisotropy in gallium phosphide crystals.

    PubMed

    Mytsyk, B G; Demyanyshyn, N M; Sakharuk, O M

    2015-10-01

    Elasto-optic coefficients of gallium phosphide (GaP) crystals were calculated on the basis of their piezo-optic and elastic coefficients. Surfaces of the spatial distribution of piezo- and elasto-optic effects in these crystals were built. The maxima of the surfaces of the elasto-optic effect and the geometries of acousto-optic interaction that correspond to these maxima were found. Ratios that describe the rotation of optical indicatrix, depending on direction of the action of uniaxial pressure or deformation on cubic crystal, were recorded. It was shown that such rotations induced by mechanical stress do not exceed 1.5° in GaP, but in some cubic crystals they can reach tens of degrees. PMID:26479633

  12. Structural and optical properties of SrCu2O2 films deposited on sapphire substrates by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Tambunan, Octolia Togibasa; Tukiman, Hadiyawarman; Parwanta, Kadek Juliana; Jeong, Da Woon; Jung, Chang Uk; Rhee, Seuk Joo; Liu, Chunli

    2012-10-01

    We deposited SrCu2O2 (SCO) films on sapphire (Al2O3) (0 0 0 1) substrates by pulsed laser deposition. The crystallographic orientation of the SCO thin film showed clear dependence on the growth temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis showed that the film deposited at 400 °C was mainly oriented in the SCO [2 0 0] direction, whereas when the growth temperature was increased to 600 °C, the SCO film showed a dominant orientation of SCO [1 1 2]. The SCO film deposited at 500 °C was obvious polycrystalline, showing multi peaks from (2 0 0), (1 1 2), and (2 1 1) diffraction in the XRD spectrum. The SCO film deposited at 600 °C showed a band gap energy of 3.3 eV and transparency up to 80% around 500 nm. The photoluminescence (PL) spectra of the SCO films grown at 500 °C and 600 °C mainly showed blue-green emission, which was attributed to the intra-band transition of the isolated Cu+ and Cu+-Cu+ pairs according to the temperature dependent-PL analysis.

  13. Improvement of optical quality of semipolar (11 2 ¯ 2 ) GaN on m-plane sapphire by in-situ epitaxial lateral overgrowth

    NASA Astrophysics Data System (ADS)

    Monavarian, Morteza; Izyumskaya, Natalia; Müller, Marcus; Metzner, Sebastian; Veit, Peter; Can, Nuri; Das, Saikat; Özgür, Ümit; Bertram, Frank; Christen, Jürgen; Morkoç, Hadis; Avrutin, Vitaliy

    2016-04-01

    Among the major obstacles for development of non-polar and semipolar GaN structures on foreign substrates are stacking faults which deteriorate the structural and optical quality of the material. In this work, an in-situ SiNx nano-network has been employed to achieve high quality heteroepitaxial semipolar (11 2 ¯ 2 ) GaN on m-plane sapphire with reduced stacking fault density. This approach involves in-situ deposition of a porous SiNx interlayer on GaN that serves as a nano-mask for the subsequent growth, which starts in the nanometer-sized pores (window regions) and then progresses laterally as well, as in the case of conventional epitaxial lateral overgrowth (ELO). The inserted SiNx nano-mask effectively prevents the propagation of defects, such as dislocations and stacking faults, in the growth direction and thus reduces their density in the overgrown layers. The resulting semipolar (11 2 ¯ 2 ) GaN layers exhibit relatively smooth surface morphology and improved optical properties (PL intensity enhanced by a factor of 5 and carrier lifetimes by 35% to 85% compared to the reference semipolar (11 2 ¯ 2 ) GaN layer) which approach to those of the c-plane in-situ nano-ELO GaN reference and, therefore, holds promise for light emitting and detecting devices.

  14. Use of a photonic crystal for optical amplifier gain control

    DOEpatents

    Lin, Shawn-Yu; Fleming, James G.; El-Kady, Ihab

    2006-07-18

    An optical amplifier having a uniform gain profile uses a photonic crystal to tune the density-of-states of a gain medium so as to modify the light emission rate between atomic states. The density-of-states of the gain medium is tuned by selecting the size, shape, dielectric constant, and spacing of a plurality of microcavity defects in the photonic crystal. The optical amplifier is particularly useful for the regeneration of DWDM signals in long optical fibers.

  15. Germanium Nanocrystals Embedded in Sapphire

    SciTech Connect

    Xu, Q.; Sharp, I.D.; Liao, C.Y.; Yi, D.O.; Ager III, J.W.; Beeman, J.W.; Yu, K.M.; Chrzan, D.C.; Haller, E.E.

    2005-04-15

    {sup 74}Ge nanocrystals are formed in a sapphire matrix by ion implantation followed by damage. Embedded nanocrystals experience large compressive stress relative to bulk, as embedded in sapphire melt very close to the bulk melting point (Tm = 936 C) whereas experience considerably lower stresses. Also, in situ TEM reveals that nanocrystals ion-beam-synthesized nanocrystals embedded in silica are observed to be spherical and measured by Raman spectroscopy of the zone center optical phonon. In contrast, reveals that the nanocrystals are faceted and have a bi-modal size distribution. Notably, the matrix remains crystalline despite the large implantation dose and corresponding thermal annealing. Transmission electron microscopy (TEM) of as-grown samples those embedded in silica exhibit a significant melting point hysteresis around T{sub m}.

  16. Lightweight optical mirrors formed in single crystal substrate

    NASA Technical Reports Server (NTRS)

    Bly, Vincent T. (Inventor)

    2006-01-01

    This invention is directed to a process for manufacturing a lightweight mirror from a single crystal material, such as single crystal silicon. As a near perfect single crystal material, single crystal silicon has much lower internal stress than a conventional material. This means much less distortion of the optical surface during the light weighting process. After being ground and polished, a single crystal silicon mirror is light weighted by removing material from the back side using ultrasonic machining. After the light weighting process, the single crystal silicon mirror may be used as-is or further figured by conventional polishing or ion milling, depending on the application and the operating wavelength.

  17. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

    1998-09-08

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.

  18. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D. Wayne; Bennett, Bryan L.; Cockroft, Nigel J.

    1998-01-01

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal.

  19. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630–720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  20. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630-720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  1. Large diameter germanium single crystals for infrared optics.

    NASA Astrophysics Data System (ADS)

    Gafni, G.; Azoulay, M.; Shiloh, C.; Noter, Y.; Saya, A.; Galron, H.; Roth, M.

    1989-09-01

    Large single crystals, up to 200 mm in diameter, of high optical quality germanium have been grown by the Czochralski technique. Postgrowth thermal treatment improves the optical homogeneity and reduces optical losses, as shown by measurements of refractive index gradients and modulation transfer function (MTF). A new approach for the piecewise combination of interferograms, as well as a polychromatic treatment of MTF, is presented.

  2. Elasto-optic effect anisotropy in calcium tungstate crystals.

    PubMed

    Demyanyshyn, N M; Mytsyk, B G; Kost, Y P; Solskii, I M; Sakharuk, O M

    2015-03-20

    The anisotropy of piezo- and elasto-optic effects in calcium tungstate CaWO4 crystals was studied by the indicatory surfaces method. On the basis of the maximum surfaces of the elasto-optic effect, the geometry of acousto-optic interaction with maximum efficiency was found. PMID:25968520

  3. Sapphire-fiber-based intrinsic Fabry-Perot interferometer

    NASA Technical Reports Server (NTRS)

    Wang, Anbo; Gollapudi, Sridhar; Murphy, Kent A.; May, Russell G.; Claus, Richard O.

    1992-01-01

    A sapphire optical fiber intrinsic Fabry-Perot interferometric sensor is demonstrated. A length of multimode sapphire fiber that functions as a Fabry-Perot cavity is spliced to a silica single-mode fiber. The interferometric signals of this sensor are produced by the interference between the reflection from the silica-sapphire fiber splice and the reflection from the free end face of the sapphire fiber. This sensor has been demonstrated for temperature measurement. A resolution of 0.2 C has been obtained over a measurement range of 310 C to 976 C.

  4. Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

    2016-01-01

    One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic <111> direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

  5. Optical limiter based on two-dimensional nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Belabbas, Amirouche; Lazoul, Mohamed

    2016-04-01

    The aim behind this work is to investigate the capabilities of nonlinear photonic crystals to achieve ultra-fast optical limiters based on third order nonlinear effects. The purpose is to combine the actions of nonlinear effects with the properties of photonic crystals in order to activate the photonic band according to the magnitude of the nonlinear effects, themselves a function of incident laser power. We are interested in designing an optical limiter based nonlinear photonic crystal operating around 1064 nm and its second harmonic at 532 nm. Indeed, a very powerful solid-state laser that can blind or destroy optical sensors and is widely available and easy to handle. In this work, we perform design and optimization by numerical simulations to determine the better structure for the nonlinear photonic crystal to achieve compact and efficient integrated optical limiter. The approach consists to analyze the band structures in Kerr-nonlinear two-dimensional photonic crystals as a function of the optical intensity. We confirm that these bands are dynamically red-shifted with regard to the bands observed in linear photonic crystals or in the case of weak nonlinear effects. The implemented approach will help to understand such phenomena as intensitydriven optical limiting with Kerr-nonlinear photonic crystals.

  6. Optical Evaluation of Digital Micromirror Devices (DMDs) with UV-Grade Fused Silica, Sapphire, and Magnesium Fluoride Windows and Longterm Reflectance of Bare Devices

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Robberto, Massimo; Heap, Sara

    2016-01-01

    Digital micromirror devices (DMDs) are commercial micro-electromechanical systems, consisting of millions of mirrors which can be individually addressed and tilted into one of two states (+/-12deg). These devices were developed to create binary patterns in video projectors, in the visible range. Commercially available DMDs are hermetically sealed and extremely reliable. Recently, DMDs have been identified as an alternative to microshutter arrays for space-based multi-object spectrometers (MOS). Specifically, the MOS at the heart of the proposed Galactic Evolution Spectroscopic Explorer (GESE) uses the DMD as a reprogrammable slit mask. Unfortunately, the protective borosilicate windows limit the use of DMDs in the UV and IR regimes, where the glass has insufficient throughput. In this work, we present our efforts to replace standard DMD windows with custom windows made from UV-grade fused silica, low-absorption optical sapphire (LAOS) and magnesium fluoride (MgF2). We present transmission measurements of the antireflection coated windows and the reflectance of bare (window removed) DMDs. Furthermore, we investigated the long-term stability of the DMD reflectance and experiments for coating DMD active area with a layer of pure aluminum (Al) to boost reflectance performance in the UV spectral range (200-400 nm).

  7. Progress in linear optics, non-linear optics and surface alignment of liquid crystals

    SciTech Connect

    Ong, H.L.; Meyer, R.B.; Hurd, A.J.; Karn, A.J.; Arakelian, S.M.; Shen, Y.R.; Sanda, P.N.; Dove, D.B.; Jansen, S.A.; Hoffmann, R.

    1989-01-01

    We first discuss the progress in linear optics, in particular, the formulation and application of geometrical-optics approximation and its generalization. We then discuss the progress in non-linear optics, in particular, the enhancement of a first-order Freedericksz transition and intrinsic optical bistability in homeotropic and parallel oriented nematic liquid crystal cells. Finally, we discuss the liquid crystal alignment and surface effects on field-induced Freedericksz transition. 50 refs.

  8. Compact dual-crystal optical parametric amplification for broadband IR pulse generation using a collinear geometry.

    PubMed

    Hong, Zuofei; Zhang, Qingbin; Lu, Peixiang

    2013-04-22

    A novel compact dual-crystal optical parametric amplification (DOPA) scheme, collinearly pumped by a Ti:sapphire laser (0.8 μm), is theoretically investigated for efficiently generating broadband IR pulses at non-degenerate wavelengths (1.2 μm~1.4 μm and 1.8 μm~2.1 μm). By inserting a pair of barium fluoride (BaF(2)) wedges between two thin β-barium borate (BBO) crystals, the group velocity mismatch (GVM) between the three interacting pulses can be compensated simultaneously. In this case, the obtained signal spectrum centered at 1.3 μm is nearly 20% broader and the conversion efficiency is increased, but also the pulse contrast and beam quality are improved due to the better temporal overlap. Furthermore, sub-two-cycle idler pulses with carrier-envelope phase (CEP) fluctuation of sub-100-mrad root mean square (RMS) can be generated. Because a tunable few-cycle IR pulse with millijoule energy is attainable in this scheme, it will contribute to ultrafast community and be particularly useful as a driving or controlling field for the generation of ultrafast coherent x-ray supercontinuum.

  9. Crystal-free Formation of Non-Oxide Optical Fiber

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

  10. Sapphire tube pressure vessel

    DOEpatents

    Outwater, John O.

    2000-01-01

    A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

  11. Crystalline perfection, third-order nonlinear optical properties and optical limiting studies of 3, 4-Dimethoxy -4‧-methoxychalcone single crystal

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Maidur, Shivaraj R.; Rao, S. Venugopal; Dharmaprakash, S. M.

    2016-07-01

    Transparent good quality single crystals of organic nonlinear optical material, 3, 4-Dimethoxy -4‧-methoxychalcone (DMMC) were grown by slow evaporation solution growth technique in acetone at ambient temperature. The lattice parameters were estimated from powder X-ray diffraction. The crystalline perfection has been evaluated by high resolution X-ray diffractometry (HRXRD). The UV-vis-NIR absorption spectrum reveals that the crystal is transparent between 440 nm and 900 nm for optical applications. The fluorescence spectrum shows a peak at about 482 nm and indicates that the crystal has a blue fluorescence emission. The third order nonlinear optical properties of solution of DMMC in N, N-Dimethylformamide (DMF) solvent has been investigated using Z-scan technique with femtosecond (fs) Ti:sapphire laser pulses at 800 nm wavelength. The calculated values of nonlinear refractive index, nonlinear absorption coefficient, and the magnitude of third-order susceptibility are of the order of - 7.7×10-14cm2/W, 1.7×10-9 cm/W and 6.7×10-12 e.s.u. respectively. The two photon absorption (2PA) cross section and molecular second-order hyperpolarizability values obtained is of the order of 10-49 cm4 s/photon/molecule and 2.8×10-31 e.s.u. respectively. The crystal shows optical-limiting (OL) effects for femtosecond laser pulses at 800 nm. The results suggest that the nonlinear properties investigated for DMMC are comparable with some of the reported chalcone derivatives and can be desirable for nonlinear optical applications.

  12. Combined CW ring single-frequency Ti:sapphire/dye laser for atom cooling and high-precision spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobtsev, Sergey; Baraulya, Vladimir; Lunin, Vladimir

    2007-04-01

    Presented in the work are the results of the development of a new combined CW ring single-frequency laser with universal design that allows efficient use as the active medium of both a Ti:Sapphire crystal and a dye jet. For the first time such combination has been implemented in a horizontal resonator configuration that offers an improvement of stability in the position of optical elements and more convenient operation. The short-term line width without the frequency stabilisation is less than 5 MHz (Ti:Sapphire) and < 10 MHz (Dye); with the frequency stabilisation to a specially designed thermo-stabilised reference interferometer with high finesse, the line width is less than 10 kHz (Ti:Sapphire) and 90 kHz (Dye), output frequency drift being less than 25 MHz/hour. The total working spectral range of the combined laser stretches from 550 to 1000 nm (550-770 nm for the Dye and 695-1000 nm for Ti:Sapphire) when pumped with 532/515-nm radiation. The maximum output power with a 10-W pump exceeds 2 W for the Ti:Sapphire configuration and is > 1 .5 W for the Dye one.

  13. Sapphire: A kinking nonlinear elastic solid

    NASA Astrophysics Data System (ADS)

    Basu, S.; Barsoum, M. W.; Kalidindi, S. R.

    2006-03-01

    Kinking nonlinear elastic (KNE) solids are a recently identified large class of solids that deform fully reversibly by the formation of dislocation-based kink bands [Barsoum et al. Phys. Rev. Lett. 92, 255508 (2004)]. We further conjectured that a high c/a ratio-that ensures that only basal slip is operative-is a sufficient condition for a solid to be KNE. The c/a ratio of sapphire is 2.73 and thus, if our conjecture is correct, it should be a KNE solid. Herein by repeatedly loading-up to 30 times-the same location of sapphire single crystals of two orientations-A and C-with a 1 μm radius spherical nanoindenter, followed by atomic force microscopy, we showed that sapphire is indeed a KNE solid. After pop-ins of the order of 100 nm, the repeated loadings give rise to fully reversible, reproducible hysteresis loops wherein the energy dissipated per unit volume per cycle Wd is of the order of 0.5 GJ/m3. Wd is due to the back and fro motion of the dislocations making up the incipient kink bands that are fully reversible. The results presented here strongly suggest that-like in graphite and mica-kink bands play a more critical role in the room temperature constrained deformation of sapphire than had hitherto been appreciated. Our interpretation is also in agreement with, and can explain most, recent nanoindentation results on sapphire.

  14. Optical stress sensor based on electro-optic compensation for photoelastic birefringence in a single crystal

    SciTech Connect

    Li Changsheng

    2011-09-20

    An optical stress sensor is proposed by using a single crystal with both electro-optic and photoelastic effects. Different from previous crystal-based stress sensors, the proposed sensor is based on electro-optic compensation for stress-induced birefringence and does not need an additional quarter-wave plate or modulator, because the stress-sensing element is simultaneously used as an electro-optic compensator. Candidate sensing materials include electro-optic crystals of the 3 m symmetry group and all glass with large Kerr coefficients. A primary experiment has demonstrated that the stress-induced birefringence in lithium niobate crystal can be compensated by its electro-optic birefringence. The proposed stress sensor is compact and low cost, and it is possible to achieve closed-loop stress measurement.

  15. Tunable optical anisotropy in three-dimensional photonic crystals

    SciTech Connect

    Che Ming; Li Zhiyuan; Liu Rongjuan

    2007-08-15

    Artificial optical birefringence can be realized in three-dimensional photonic crystals with a uniaxial structural symmetry: e.g., woodpile photonic crystals with a tetragonal lattice structure in the long-wavelength limit. The ordinary and extraordinary indices of refraction are determined from calculation of the reflection coefficient for a plane wave incident on the surface of a semi-infinite photonic crystal at different angles. We find that the anisotropy can be widely tuned by simply changing the width and thickness of the dielectric rod. A large relative negative anisotropy over 33% is found. A transition from positive anisotropy to negative anisotropy can be readily achieved. At certain parameters, a structurally anisotropic nanostructure can behave like an optically isotropic medium. Our study opens a window to use artificial nanostructures to create an arbitrary optical anisotropy that is not possible in natural crystals.

  16. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  17. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  18. Process of making cryogenically cooled high thermal performance crystal optics

    SciTech Connect

    Kuzay, T.M.

    1990-06-29

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N{sub 2} is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  19. Evolution of molecular crystal optical phonons near structural phase transitions

    NASA Astrophysics Data System (ADS)

    Michki, Nigel; Niessen, Katherine; Xu, Mengyang; Markelz, Andrea

    Molecular crystals are increasingly important photonic and electronic materials. For example organic semiconductors are lightweight compared to inorganic semiconductors and have inexpensive scale up processing with roll to roll printing. However their implementation is limited by their environmental sensitivity, in part arising from the weak intermolecular interactions of the crystal. These weak interactions result in optical phonons in the terahertz frequency range. We examine the evolution of intermolecular interactions near structural phase transitions by measuring the optical phonons as a function of temperature and crystal orientation using terahertz time-domain spectroscopy. The measured orientation dependence of the resonances provides an additional constraint for comparison of the observed spectra with the density functional calculations, enabling us to follow specific phonon modes. We observe crystal reorganization near 350 K for oxalic acid as it transforms from dihydrate to anhydrous form. We also report the first THz spectra for the molecular crystal fructose through its melting point.

  20. A novel organic nonlinear optical crystal: Creatininium succinate

    NASA Astrophysics Data System (ADS)

    Thirumurugan, R.; Anitha, K.

    2015-06-01

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV-Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.

  1. A novel organic nonlinear optical crystal: Creatininium succinate

    SciTech Connect

    Thirumurugan, R.; Anitha, K.

    2015-06-24

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.

  2. Dispersion of optical activity of magnesium sulfite hexahydrate single crystals

    NASA Astrophysics Data System (ADS)

    Dimov, T.; Bunzarov, Zh; Iliev, I.; Petkova, P.; Tzoukrovski, Y.

    2010-11-01

    The magnesium sulfite hexahydrate (MgSO3.6H2O) crystals are unique because they are the only representative (with sodium periodate) of the crystallographic class C3 (without a center of symmetry). The crystal symmetry suggests presence of nonlinearity, piezo- and pyro-electric properties and gyrotropy as well. Single crystals of MgSO3.6H2O (pure and doped with Ni, Co and Zn) for the time being are grown only by the original method developed in the Laboratory for Crystal growth at the Faculty of Physics in Sofia University. The first results of optical activity of pure MgSO3.6H2O and Zn doped MgSO3.6H2O crystals are described and analyzed in a wide spectral range. The optical activity manifests itself in the direction (0001) as a rotation of the polarization plane.

  3. Crystal growth of organics for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Mazelsky, R.

    1993-01-01

    The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

  4. Optical properties of doped potassium gadolinium tungstate single crystals

    NASA Astrophysics Data System (ADS)

    Michalski, E.; Zmija, Jozef; Mierczyk, Zygmunt; Majchrowski, Andrzej; Kopczynski, Krzysztof; Cichowski, S.; Wojtanowski, J.

    2001-08-01

    Single crystals of double tungstates find applications as laser materials having very good parameters. One of the intensively investigated material sis KGD(WO4)2 doped with rare earth elements. Single crystal of KGd(WO4)2 were grown with the use of Top Seeded Solution Growth technique from K2W2O7 solvent. The crystals have low absorption loses and show high lasing efficiency. Optical investigations of as grown KGW:Nd single crystal confirmed their good optical quality and high absorption coefficient near 810 nm, what in connection with strong luminescence near 1067 nm allows fabrication of diode pumped microchip lasers working both in CW and giant pulse regime. Absorption and luminescence spectra of Nd3+ doped KGW single crystals are presented. Laser action was obtained in form of 128.5 kHz train of 100 ns giant pluses due to YAG:Cr4+ passive Q-switch.

  5. Optically tunable and rewritable diffraction grating with photoaligned liquid crystals.

    PubMed

    Sun, J; Srivastava, A K; Wang, L; Chigrinov, V G; Kwok, H S

    2013-07-01

    An optically tunable and rewritable liquid crystal (LC) diffraction grating cell has been revealed that consists of an optically active and an optically passive alignment layer. The grating profile is created by confining the LC director distribution in alternate planar and twisted alignment domains by means of photoalignment of the LCs. The proposed grating is optically tunable for diffractive and nondiffractive states with a small response time that depends on the exposure energy and LC parameters. In addition, the grating can be erased and rewritten for different diffracting characteristics. These optically tunable diffractive elements could find application in various photonic devices. PMID:23811922

  6. Piezo-optic surfaces of lithium niobate crystals

    SciTech Connect

    Mytsyk, B. G. Dem'yanyshyn, N. M.

    2006-07-15

    A method of construction of the spatial distribution of the piezo-optic effect in crystals is proposed. A particular case of this method is the known technique of construction of indicator surfaces of the piezo-optic effect. The essence of the proposed method consists in determining the difference in the radius vectors of the optical indicatrix perturbed by stress and the free optical indicatrix. It is shown that this difference in the radius vectors is mathematically identical to the law of transformation of the piezo-optic tensor during the rotation of the coordinate system.

  7. Band structure and optical properties of diglycine nitrate crystal

    NASA Astrophysics Data System (ADS)

    Andriyevsky, Bohdan; Ciepluch-Trojanek, Wioleta; Romanyuk, Mykola; Patryn, Aleksy; Jaskólski, Marcin

    2005-07-01

    Experimental and theoretical investigations of the electron energy characteristics and optical spectra for diglycine nitrate crystal (DGN), (NH 2CH 2COOH) 2·HNO 3, in the paraelectric phase ( T=295 K) are presented. Spectral dispersion of light reflection R( E) have been measured in the range of 3-22 eV and the optical functions n( E) and k( E) have been calculated using Kramers-Kronig relations. First principal calculations of the electron energy characteristic and optical spectra of DGN crystal have been performed in the frame of density functional theory using CASTEP code (CAmbridge Serial Total Energy Package). Optical transitions forming the low-energy edge of fundamental absorption are associated with the nitrate groups NO 3. Peculiarities of the band structure and DOS projected onto glycine and NO 3 groups confirm the molecular character of DGN crystal.

  8. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, Ralph

    1994-01-11

    A non-linear optical crystal vibration sensing device (10) including a photorefractive crystal (26) and a laser (12). The laser (12 ) produces a coherent light beam (14) which is split by a beam splitter (18) into a first laser beam (20) and a second laser beam (22). After passing through the crystal (26) the first laser beam (20) is counter-propagated back upon itself by a retro-mirror (32), creating a third laser beam (30). The laser beams (20, 22, 30) are modulated, due to the mixing effect within the crystal (26) by vibration of the crystal (30). In the third laser beam (30), modulation is stable and such modulation is converted by a photodetector (34) into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal (26).

  9. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, R.

    1994-08-09

    A non-linear optical crystal vibration sensing device including a photorefractive crystal and a laser is disclosed. The laser produces a coherent light beam which is split by a beam splitter into a first laser beam and a second laser beam. After passing through the crystal the first laser beam is counter-propagated back upon itself by a retro-mirror, creating a third laser beam. The laser beams are modulated, due to the mixing effect within the crystal by vibration of the crystal. In the third laser beam, modulation is stable and such modulation is converted by a photodetector into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal. 3 figs.

  10. Damage testing of sapphire and Ti: sapphire laser materials

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Diffusion bonded sapphire and Ti (Titanium). Sapphire laser materials that will be damage tested to determine if there is an increase in damage threshold. Photographed in building 1145, photographic studio.

  11. Surface mediated nonlinear optic effects in liquid crystals

    NASA Astrophysics Data System (ADS)

    Merlin, Jessica M.

    Liquid crystals have become a significant part of technology, mainly through their use in the display industry. This is due in part to the fact that the optical properties of liquid crystals are easily manipulated electronically. It has been recognized that the optical properties liquid crystals may also be controlled using light. Because of this, there are other various applications being explored for liquid crystals in photorefraction, optical limiting and switching, and in spatial light modulators. Although, the photorefractive effect was reported in liquid crystals over 10 years ago, there is still controversy over the exact mechanism for the reorientation of the liquid crystal director. This difficulty may be due in part to the fact that it is difficult to characterize the effect using photorefractive measurements and figures of merit. The optical and electronic control of liquid crystals will be studied here using a Friedericksz transition measurement in a twist cell geometry. This type of apparatus was chosen because it leads to a more direct demonstration of the surface effect. Namely, by studying changes in the Friedericksz transition threshold in a twist cell, a more direct observation of changes in the internal field may be observed. First a brief introduction to liquid crystals and their role in technology will be presented. This will be followed by a more rigorous discussion of the physics of liquid crystals and a review of the important literature. The experimental apparatus and the materials and cell geometry used will be described followed by the results of those measurements. Finally, the results will be considered in terms of a model involving interfacial charge and discussed in the context of previous work.

  12. Crystal growth and characterization of new semiorganic nonlinear optical single crystals

    NASA Astrophysics Data System (ADS)

    Kulshrestha, Shobha; Shrivastava, A. K.

    2016-05-01

    An organic material of a L-histidine monohydrochloride single crystal was grown in a distilled water solution using the slow evaporation method at 40-45°C. The grown crystal was transparent and colourless, with a size of about 20 × 9 × 5 mm3, obtained within a period of 21 days. The solubility of grown crystals have found out at various temperatures. The UV-visible transmittance studies show that the grown crystals have wide optical transparency in the entire visible region It is observed that the crystal has transparency window from 255nm to 700nm and its energy gap (Eg) found to be is 3.1eV. The grown crystal was subjected to powder X-ray diffraction analysis, confirming that the orthorhombic crystalline nature of the crystal. To identify the surface morphology, the as grown crystal was subjected to FE-SEM technique. The chemical composition of the grown crystal was estimated by Energy dispersive X-ray analysis. The optical behaviour of the grown crystal was analyzed by PL study.

  13. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    SciTech Connect

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-04-15

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm{sup 2} at 1064 nm laser radiation. Highlights: Black-Right-Pointing-Pointer It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. Black-Right-Pointing-Pointer Wide optical transparency window between 280 nm and 1100 nm. Black-Right-Pointing-Pointer Negative birefringence crystal and dispersion of birefringence is negligibly small. Black-Right-Pointing-Pointer Thermal study reveals that the grown crystal is stable up to 210 Degree-Sign C. Black-Right-Pointing-Pointer Multiple shot surface laser damage threshold is 0.30 GW/cm{sup 2} at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV-vis-IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has

  14. Nonreciprocal optical properties in resonant hybrid photonic crystals

    NASA Astrophysics Data System (ADS)

    D'Andrea, A.; Tomassini, N.

    2016-07-01

    The present work is devoted to the theoretical study of the nonreciprocal optical properties in hybrid (isotropic and anisotropic) periodic multilayers for photon energy values chosen close to the electronic energy gaps of semiconductors (excitons). The optical properties of these resonant nonmagnetic photonic crystals, where linear and quadratic spatial dispersion effects are both present, will be studied in the framework of exciton-polariton self-consistent solutions of the Maxwell and Schrödinger equations in the effective-mass approximation. The main interesting optical properties, namely, giant transmission, absorption suppression, and optical unidirectional propagation, will be computed by implementing a two-layer "minimum model."

  15. Crystal structure, growth and nonlinear optical studies of isonicotinamide p-nitrophenol: A new organic crystal for optical limiting applications

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi, A.; Vidyavathy, B.; Vinitha, G.

    2016-08-01

    Isonicotinamide p-nitrophenol (ICPNP), a new organic material, was synthesized using methanol solvent. Single crystals of ICPNP were grown using a slow evaporation solution growth technique. Crystal structure of ICPNP is elucidated by single crystal X-ray diffraction analysis. It belongs to monoclinic crystal system with space group of P21/c. It forms two dimensional networks by O-H…O, N-H…O and C-H…O hydrogen bonds. The molecular structure of ICPNP was further confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance range and the lower cut-off wavelength (421 nm) with the optical band gap (2.90 eV) of the ICPNP crystal were determined by UV-vis-NIR spectral study. Thermal behavior of ICPNP was studied by thermo gravimetric and differential thermal analyses (TG/DTA). The relative dielectric permittivity was calculated for various temperature ranges. Laser damage threshold of ICPNP crystal was found to be 1.9 GW/cm2 using an Nd:YAG laser. A Z-scan technique was employed to measure the nonlinear absorption coefficient, nonlinear refractive index and nonlinear optical susceptibility. Optical limiting behavior of ICPNP was observed at 35 mW input power.

  16. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOEpatents

    Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

    1996-08-06

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

  17. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOEpatents

    Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.

    1996-01-01

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.

  18. Optical properties of Nd:YCOB crystal

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Zheng, Wei; Liu, Xinrong; Wang, Biao

    2001-10-01

    Ca4YO(BO3)3 crystal doped with Nd3+ has been grown by the Czochralski method under air atmosphere. The growth conditions were studied in the paper. X-ray powder diffractogram, the absorption spectra and infrared spectra have been measured. The effects of ions in the crystal on the absorption peak of OH- have been also discussed. The second harmonic generation (SHG) and self- frequency-doubling (SFD) experiments were carried out on the sample with the dimension of 4x4x8mm3.

  19. Optical modulator based on coupled photonic crystal cavities

    NASA Astrophysics Data System (ADS)

    Serafimovich, Pavel G.; Kazanskiy, Nikolay L.

    2016-07-01

    We propose and numerically investigate an optical signal modulator based on two-photonic crystal nanobeam cavities coupled through a waveguide. The suggested modulator shifts the resonant frequency over a scalable range. We design a compact optical modulator based on photonic crystal nanobeams cavities that exhibits high stability to manufacturing. Photonic crystal waveguide tuning in the low-intensity region of the resonant mode is demonstrated. The advantages of the suggested approach over the single-resonator optical modulator approaches include the possibilities to shift the modulator frequency over a scalable range that depends on switching energy level and to effectively electrically tune the device in the low-intensity region of the resonant mode.

  20. Linear optical and SHG characterization of new chalcone crystals

    NASA Astrophysics Data System (ADS)

    Raghavendra, S.; Jayarama, A.; Shekhara Shetty, T. Chandra; Dharmaprakash, S. M.

    2013-02-01

    Two new non linear optical (NLO) materials: (2E)-1-(4-chloro-3-methyl phenyl)-3-(2, 3-dimethoxy phenyl) prop-2-en-1-one (CMDP) and (2E)-1-(4-chloro-3-methylphenyl)-3-(2,4,5-tri methoxy phenyl) prop-2-en-1-one (CMTP) were crystallized using methanol solution. Various functional groups present in CMDP and CMTP were identified by FTIR spectra. The second harmonic generation (SHG) in CMDP and CMTP crystals was observed for a Q-switched and pulsed Nd:YAG laser of wavelength 1064nm. The SHG efficiency of the CMDP and CMTP was found to be 0.5 and 5 times that of urea, respectively. The linear optical properties of the compounds have been determined from the absorbance spectrum, collected using UV-VIS spectrophotometer. The absorption edges, direct and indirect optical band gaps of the crystals were determined.

  1. Modeling of Optical Aberration Correction using a Liquid Crystal Device

    NASA Technical Reports Server (NTRS)

    Xinghua, Wang; Bin, Wang; McManamon, Paul F.; Pouch, John J.; Miranda, Felix A.

    2006-01-01

    Gruneisen (sup 1-3), has shown that small, light weight, liquid crystal based devices can correct for the optical distortion caused by an imperfect primary mirror in a telescope and has discussed the efficiency of this correction. In this paper we expand on that work and propose a semi-analytical approach for quantifying the efficiency of a liquid crystal based wavefront corrector for this application.

  2. Optically induced melting of colloidal crystals and their recrystallization.

    PubMed

    Harada, Masashi; Ishii, Masahiko; Nakamura, Hiroshi

    2007-04-15

    Colloidal crystals melt by applying focused light of optical tweezers and recrystallize after removing it. The disturbed zone by the light grows radially from the focus point and the ordering starts from the interface with the crystal. Although the larger disturbed zone is observed for the higher power optical tweezers, a master curve is extracted by normalization of the disturbed zone. The temporal changes of the normalized disturbed zone are well described with exponential functions, indicating that the melting and recrystallization process is governed by a simple relaxation mechanism.

  3. Growth morphologies and optical properties of LTA single crystal.

    PubMed

    Liu, Xiaojing; Ren, Miaojuan; Chen, Gang; Wang, Peiji

    2013-12-01

    Atomic force microscopy (AFM) has been used to study the growth morphologies of l-threonine acetate (abbreviated as LTA) crystal. Spiral growth hillocks and typical step patterns are described and discussed. Nuclei with various shapes often distribute at the larger step terraces. Eventually, in order to investigate microscopic second order nonlinear optical properties of LTA crystals, the molecular dipole moment (μ), polarizability (α), and first hyperpolarizability (β) were computed using a series of basis sets including polarized and diffuse functions at the framework of Hartree-Fock and density functional theory methods. The study is helpful to the further development of l-threonine analogs with improved nonlinear optical properties.

  4. Optical model of transient light scattering in ferroelectric liquid crystals

    SciTech Connect

    Loiko, V. A. Konkolovich, A. V.; Miskevich, A. A.

    2009-03-15

    A static optical model is developed for the effect of field-induced transient scattering on coherent light transmission through ferroelectric liquid crystals. Scattering processes are described by introducing an optically anisotropic medium containing scatterers (transient domains). The results presented in the paper are obtained for a plane parallel layer of ferroelectric liquid crystals with a planar helicoidal structure under normal illumination with a linearly polarized plane wave. An analysis is presented of the coherent transmittance of the layer in static applied electric fields.

  5. Optical properties of ultra-thin (< 30 nm) GaN layers on c-sapphire substrates with different initial growth conditions measured by surface-plasmon enhanced Raman scattering.

    PubMed

    Kim, Ho-Jong; Kim, Tae-Soo; Lee, Jin-Gyu; Song, Jung Hoon

    2014-11-01

    We have carried out surface-plasmon enhanced Raman spectroscopy (SERS) on 30 nm-thick GaN samples grown at various temperatures, in order to investigate the properties of ultra thin GaN films on sapphire. We found that the properties, such as the strain and the free-carrier density of the thin layers, were sensitively affected by the growth temperatures. Our results show that SERS, by selectively enhancing the Raman signal near the surface, can be a very useful technique to investigate the optical properties of ultra-thin GaN films and their initial growth mode.

  6. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    PubMed

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system.

  7. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    PubMed

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system. PMID:18273287

  8. Optical Properties of TGS Crystal with L-Valine Admixture

    SciTech Connect

    Stadnyk, V. Yo. Romanyuk, N. A.; Kiryk, Yu. I.

    2010-11-15

    The thermal expansion and temperature and the spectral dependences of the refractive indices and birefringence of triglycine sulphate (TGS) crystals with a 5% L-valine admixture have been investigated. It is established that the introduction of L-valine weakens the temperature dependence of the refractive indices and the birefringence and thermal expansion of TGS crystals. The parameters of the Sellmeier formula, refractions, and electronic polarizabilities are calculated. The changes observed may be related to the increase in hardness of admixture-containing crystals, the decrease in the spontaneous polarization, the replacement of the refraction components of the valine bond, or the spontaneous electro-optic effect.

  9. Highly Non-Linear Optical (NLO) organic crystals

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    This research project involves the synthesis and characterization of organic materials having powerful nonlinear optical (NLO) properties and the growth of highly ordered crystals and monomolecular films of these materials. Research in four areas is discussed: theoretical design of new materials, characterization of NLO materials, synthesis of new materials and development of coupling procedures for forming layered films, and improvement of the techniques for vapor phase and solution phase growth of high quality organic crystals. Knowledge gained from these experiments will form the basis for experiments in the growth of these crystals.

  10. Optical-diffraction method for determining crystal orientation

    DOEpatents

    Sopori, B.L.

    1982-05-07

    Disclosed is an optical diffraction technique for characterizing the three-dimensional orientation of a crystal sample. An arbitrary surface of the crystal sample is texture etched so as to generate a pseudo-periodic diffraction grating on the surface. A laser light beam is then directed onto the etched surface, and the reflected light forms a farfield diffraction pattern in reflection. Parameters of the diffraction pattern, such as the geometry and angular dispersion of the diffracted beam are then related to grating shape of the etched surface which is in turn related to crystal orientation. This technique may be used for examining polycrystalline silicon for use in solar cells.

  11. Assembly of optical-scale dumbbells into dense photonic crystals.

    PubMed

    Forster, Jason D; Park, Jin-Gyu; Mittal, Manish; Noh, Heeso; Schreck, Carl F; O'Hern, Corey S; Cao, Hui; Furst, Eric M; Dufresne, Eric R

    2011-08-23

    We describe the self-assembly of nonspherical particles into crystals with novel structure and optical properties combining a partial photonic band gap with birefringence that can be modulated by an external field or quenched by solvent evaporation. Specifically, we study symmetric optical-scale polymer dumbbells with an aspect ratio of 1.58. Hard particles with this geometry have been predicted to crystallize in equilibrium at high concentrations. However, unlike spherical particles, which readily crystallize in the bulk, previous experiments have shown that these dumbbells crystallize only under strong confinement. Here, we demonstrate the use of an external electric field to align and assemble the dumbbells to make a birefringent suspension with structural color. When the electric field is turned off, the dumbbells rapidly lose their orientational order and the color and birefringence quickly go away. In this way, dumbbells combine the structural color of photonic crystals with the field addressability of liquid crystals. In addition, we find that if the solvent is removed in the presence of an electric field, the particles self-assemble into a novel, dense crystalline packing hundreds of particles thick. Analysis of the crystal structure indicates that the dumbbells have a packing fraction of 0.7862, higher than the densest known packings of spheres and ellipsoids. We perform numerical experiments to more generally demonstrate the importance of controlling the orientation of anisotropic particles during a concentration quench to achieve long-range order.

  12. Final EDP Ti: sapphire amplifiers for ELI project

    NASA Astrophysics Data System (ADS)

    Chvykov, Vladimir; Kalashnikov, Mikhail; Osvay, Károly

    2015-05-01

    Recently several ultrahigh intensity Chirped Pulse Amplification (CPA) laser systems have reached petawatt output powers [1, 2] setting the next milestone at tens or even hundreds petawatts for the next three to ten years [3, 4]. These remarkable results were reached when laser amplifiers (opposite to Optical Parametric Amplification (OPA) [5]) were used as final ones and from them Ti:Sapphire crystals supposed to be the working horses as well in the future design of these laser systems. Nevertheless, the main limitation that arises on the path toward ultrahigh output power and intensity is the restriction on the pumping and extraction energy imposed by Transverse Amplified Spontaneous Emission (TASE) [6] and/or transverse parasitic generation (TPG) [7] within the large aperture of the disc-shape amplifier volume.

  13. Compressive failure in sapphire under CO2 laser heating

    NASA Astrophysics Data System (ADS)

    Miles, P. A.; Gallagher, J.; Gentilman, R. L.

    1980-07-01

    Irreversible changes were observed in sapphire crystals subjected to surface heating by CO2 laser irradiation at levels above 300 watts/square centimeter. The changes are interpreted as due to plastic flow under compressive stress at temperatures above 900 C. The recognition of possible compressive failures in refractory oxides is of importance in defining laser tolerance levels in high power optics, in the design of laser heating experiments to assess the thermal shock resistance of materials, and possibly in the field of laser assisted machining of ceramics. A detailed thermomechanical analysis was carried out to predict the temperature and stress conditions throughout disk samples as a function of time, heat flux level and flux distribution. Compressive stresses in excess of 200,000 psi were generated. Compressive failure is likely to precede tensile fracture in most experiments where partially heated disks are used.

  14. Crystal structure and characterization of a novel organic optical crystal: 2-Aminopyridinium trichloroacetate

    SciTech Connect

    Dhanaraj, P.V.; Rajesh, N.P.; Vinitha, G.; Bhagavannarayana, G.

    2011-05-15

    Research highlights: {yields} Good quality crystals of 2-aminopyridinium trichloroacetate were grown for first time. {yields} 2-Aminopyridinium trichloroacetate crystal belongs to monoclinic crystal system with space group P21/c. {yields} 2-Aminopyridinium trichloroacetate crystal exhibits third order nonlinear optical properties. {yields} 2-Aminopyridinium trichloroacetate is a low dielectric constant material. -- Abstract: 2-Aminopyridinium trichloroacetate, a novel organic optical material has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. 2-Aminopyridinium trichloroacetate crystallizes in monoclinic system with space group P2{sub 1}/c and the lattice parameters are a = 8.598(5) A, b = 11.336(2) A, c = 11.023(2) A, {beta} = 102.83(1){sup o} and volume = 1047.5(3) A{sup 3}. High-resolution X-ray diffraction measurements were performed to analyze the structural perfection of the grown crystals. Thermal analysis shows a sharp endothermic peak at 124 {sup o}C due to melting reaction of 2-aminopyridinium trichloroacetate. UV-vis-NIR studies reveal that 2-aminopyridinium trichloroacetate has UV cutoff wavelength at 354 nm. Dielectric studies show that dielectric constant and dielectric loss decreases with increasing frequency and finally it becomes almost a constant at higher frequencies for all temperatures. The negative nonlinear optical parameters of 2-aminopyridinium trichloroacetate were derived by the Z-scan technique.

  15. Web-interfaced Nonlinear Optical Waveguide and Photonic Crystal Simulator

    SciTech Connect

    S. Enguehard; B. Hatfield

    2002-06-15

    We report on the development of new methods for the computation of spectral bandpass properties of photonic crystals and for the electromagnetic wave propagation in second order nonlinear optical waveguides. The former is based on a generalization of characteristic matrices while the latter is based on path integrals. Accurate and efficient propagation methods and algorithms form the basis for the construction of design tools for integrated optics.

  16. Polychromatic Optical Vortex Generation from Patterned Cholesteric Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-01

    Generation of optical vortices is described in cholesteric liquid crystals with a singular point in the spatial distribution of a helix phase. The phenomenon uses the fact that a Bragg reflected light phase varies in proportion to the spatial phase of the helix, both at normal and oblique incidences. Our proposal enables high-efficiency, polychromatic generation of optical vortices without the need of a cumbersome fabrication process and fine-tuning.

  17. Polychromatic Optical Vortex Generation from Patterned Cholesteric Liquid Crystals.

    PubMed

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-24

    Generation of optical vortices is described in cholesteric liquid crystals with a singular point in the spatial distribution of a helix phase. The phenomenon uses the fact that a Bragg reflected light phase varies in proportion to the spatial phase of the helix, both at normal and oblique incidences. Our proposal enables high-efficiency, polychromatic generation of optical vortices without the need of a cumbersome fabrication process and fine-tuning. PMID:27391724

  18. Optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals

    SciTech Connect

    Hamidi, S. M.

    2012-01-15

    In this paper, the optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals have been investigated. We use transfer matrix method to solve our magnetized coupled resonator plasma photonic crystals consist of dielectric and magnetized plasma layers. The results of the change in the optical and magneto-optical properties of structure as a result of the alteration in the structural properties such as thickness, plasma frequency and collision frequency, plasma filling factor, number of resonators and dielectric constant of dielectric layers and external magnetic field have been reported. The main feature of this structure is a good magneto-optical rotation that takes place at the defect modes and the edge of photonic band gap of our proposed optical magnetized plasma waveguide. Our outcomes demonstrate the potential applications of the device for tunable and adjustable filters or reflectors and active magneto-optic in microwave devices under structural parameter and external magnetic field.

  19. Optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals

    NASA Astrophysics Data System (ADS)

    Hamidi, S. M.

    2012-01-01

    In this paper, the optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals have been investigated. We use transfer matrix method to solve our magnetized coupled resonator plasma photonic crystals consist of dielectric and magnetized plasma layers. The results of the change in the optical and magneto-optical properties of structure as a result of the alteration in the structural properties such as thickness, plasma frequency and collision frequency, plasma filling factor, number of resonators and dielectric constant of dielectric layers and external magnetic field have been reported. The main feature of this structure is a good magneto-optical rotation that takes place at the defect modes and the edge of photonic band gap of our proposed optical magnetized plasma waveguide. Our outcomes demonstrate the potential applications of the device for tunable and adjustable filters or reflectors and active magneto-optic in microwave devices under structural parameter and external magnetic field.

  20. Comments on the paper: 'Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal'

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bikshandarkoil R.; Naik, Suvidha G.; Dhavskar, Kiran T.

    2016-02-01

    We argue that the 'L-aspartic acid nickel chloride' crystal reported by the authors of the title paper (Optics Communications, 291 (2013) 304-308) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

  1. Optical Properties of Irradiated Topaz Crystals

    NASA Astrophysics Data System (ADS)

    Skvortsova, V.; Mironova-Ulmane, N.; Trinkler, L.

    2015-04-01

    The results of an investigation of UV-Visible absorption and photoluminescence spectra of colorless topaz before and after neutron irradiation, natural blue topaz from Ukraine, and yellow topaz are presented. We assume that the absorption band ∼ 620 nm and broad emission band 300-700 nm in topaz crystals are associated with exchange interaction between a radiation defect (anion vacancies, which capture one or two electrons) and impurity ions Cr3+, Fe3+ and Mn2+.

  2. Magneto-photonic crystals for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Dissanayake, Neluka

    Among the optical structures investigated for optical sensing purpose, a significant amount of research has been conducted on photonic crystal based sensors. A particular advantage of photonic crystal based sensors is that they show superior sensitivity for ultra-small volume sensing. In this study we investigate polarization changes in response to the changes in the cover index of magneto-optic active photonic band gap structures. One-dimensional photonic-band gap structures fabricated on iron garnet materials yield large polarization rotations at the band gap edges. The enhanced polarization effects serve as an excellent tool for chemical sensing showing high degree of sensitivity for photonic crystal cover refractive index changes. The one dimensional waveguide photonic crystals are fabricated on single-layer bismuth-substituted rare earth iron garnet films ((Bi, Y, Lu)3(Fe, Ga)5O12 ) grown by liquid phase epitaxy on gadolinium gallium garnet substrates. Band gaps have been observed where Bragg scattering conditions links forward-going fundamental waveguide modes to backscattered high-order waveguide modes. Large near-band-edge polarization rotations which increase progressively with backscattered-mode order have been experimentally demonstrated for multiple samples with different composition, film thickness and fabrication parameters. Experimental findings are supported by theoretical analysis of Bloch modes polarization states showing that large near stop-band edge rotations are induced by the magneto-photonic crystal. Theoretical and experimental analysis conducted on polarization rotation sensitivity to waveguide photonic crystal cover refractive index changes shows a monotonic enhancement of the rotation with cover index. The sensor is further developed for selective chemical sensing by employing Polypyrrole as the photonic crystal cover layer. Polypyrrole is one of the extensively studied conducting polymers for selective analyte detection. Successful

  3. Structural and optical properties of a new chalcone single crystal

    NASA Astrophysics Data System (ADS)

    Rajesh Kumar, P. C.; Ravindrachary, V.; Janardhana, K.; Poojary, Boja

    2012-09-01

    A new nonlinear optical material 1-(4-methylthiophenyl)-3-(4-methoxyphenyl)prop-2-en-1-one with molecular formula C17H16O2S was synthesized by using the Claisen-Schmidt condensation reaction method. The Various functional groups present in the compound were identified using recorded FT-IR spectrum. The crystal growth parameters have been studied using solubility test and acetone is found to be a very good solvent for the crystal growth at an ambient temperature. The transparent high quality single crystals up to a size of 26×2×2 mm3 were grown using the slow evaporation solution growth technique. UV-visible study was carried out and the spectrum reveals that the crystal is transparent in the entire visible region and absorptive in the UV region. The refractive index is determined using Brewster's angle method. The optical energy band gap of the material is measured using Tauc's plot and the direct method. The single crystal XRD of MMPP crystal shows the following cell parameters: a=5.9626(2) Å, b=15.3022(6) Å, c=16.0385(7) Å, α=β=γ=90°, volume=1463.37(10) Å3 with a space group of Pna21. The compound MMPP exhibits optical nonlinearity (NLO) and its second order NLO efficiency is 3.15 times to that of urea. The effect of functional groups OCH3 and SCH3 on the non-linearity as well as the structural property of the compound has been discussed. The crystal is thermally stable. High NLO efficiency, good thermal stability, good transparency and ability to grow as a high quality single crystal make this material very attractive for opto-electronic applications.

  4. Effects of MgO buffer annealing on optical and electrical quality of P-MBE grown ZnO films on c-sapphire

    NASA Astrophysics Data System (ADS)

    Setiawan, A.; Yao, T.

    2016-04-01

    Zinc oxide (ZnO) has been attracting much attention because of its potential applications in photonic and optoelectronic devices. In this present study, we investigated the effect of MgO buffer annealing on the optical and electrical quality of P-MBE grown ZnO films on c-sapphire with MgO buffer layer. The optical quality was observed by low-temperature PL (photoluminescence) measurement in the near band edge emission region measured at 10K and at 77K. The emission line located at 3.368eV dominates the spectrum in both samples (ZnO with and without MgO buffer annealing) at 10K and 77K. This emission can be divided into two peaks, 3.367eV and 3.363eV and assigned as I2 (ionized donor bound excitons emission) and I4 (Hydrogen donor related emission), respectively. The relative intensity of these donor bound exactions to free exaction emission of the sample without MgO buffer annealing is greater than that of the sample with MgO buffer annealing. Comparison of the PL spectra of ZnO with and without annealing revealed that the intensity of free exciton emission from the sample with MgO buffer annealing is twice of that from the sample without annealing. We also found that the intensity of deep-level broad emission is reduced by about 1/3 by MgO-buffer annealing. Hence, the decrease of deep level emission intensity and the increase of free exciton emission intensity by annealing of MgO buffer corresponds to the reduction of defects of the ZnO film. The PL properties also suggest that there are fewer nonradiative recombination centers in ZnO layers with MgO buffer annealing than those in ZnO layers grown without MgO buffer annealing. The electrical quality was measured by room temperature Hall measurements. We found that the samples have a background n-type carrier concentration. The ZnO samples with MgO buffer annealing has a carrier concentration of 1.17×1017 cm-3 and Hall mobility of 120 cm2/V.s, while the ZnO sample without MgO buffer annealing has a carrier

  5. Propagation optical quarks after an uniaxial crystal: the experiment

    NASA Astrophysics Data System (ADS)

    Egorov, Yu. A.; Konovalenko, V. L.; Zinovev, A. O.; Anischenko, P. M.; Glumova, M. V.

    2013-12-01

    There is a lots of different papers reporting about the propagation of the different types of an optical beams in a uniaxial crystals are known by that time. This beams are: Lager-Gaussian and Bessel- Gaussian beams. It is common for all this types of beams, that if propagation axis and crystal axis coincides, and accident beam had a circular polarization, are can get type spiral type degenerated umbilici, which corresponds to the charge 2 optical vortex in the orthogonal polarized beam component, generated by crystal [1] (Fig 1). This generation accurse due to total angular momentum conservation law symmetry axis of the crystal. One to the changing of the spin momentum which is associated with the beam polarization, this leads to the orbital momentum changes that associated with topological charge of formed orthogonal circular component. Double charged optical vortex could be easily perturbed by tilting beam axis with respect to the crystal axis. If the tilt angles are small (<0.1°) central umbilici splits on two lemons and the surrounding ring umbilici splits on two pairs of monster-star. The further increasing of the tilt angle leads to the topological charge of circular components becomes, equal, and additional orbital moment correspond to the beam mass center displacement.

  6. Study of green light-emitting diodes grown on semipolar (11-22) GaN/m-sapphire with different crystal qualities

    NASA Astrophysics Data System (ADS)

    Oh, Dong-Sub; Jang, Jong-Jin; Nam, Okhyun; Song, Keun-Man; Lee, Sung-Nam

    2011-07-01

    We investigated the anisotropic optical and structural properties of semipolar (11-22) InGaN-based green light emitting diodes (LEDs) grown on GaN templates with the different crystallographic properties. By introducing the N 2-GaN as a seed layer grown at a N 2 atmosphere, the full width at half maximum (FWHMs) of X-ray rocking curves (XRCs) for semipolar GaN templates were decreased from 1331 to 727 arcsec and from 1955 to 1076 arcsec with the incident beam directions of [11-2-3] and [1-100], respectively. It was found that the interfacial qualities of InGaN/GaN quantum wells (QWs) would be improved by reducing the FWHMs of XRCs with regardless of crystallographic directions. However, the thickness uniformity of InGaN QWs was significantly deteriorated for the direction of [11-2-3] rather than [1-100]. In addition, the EL intensity of semipolar green LEDs would be increased by enhancing the crystal quality of semipolar GaN template, which could also be resulted in the formation of abrupt interface and the enhancement of homogeneity at InGaN/GaN QWs.

  7. Crystal growth and optical properties of rare earth calcium oxoborates

    NASA Astrophysics Data System (ADS)

    Vivien, Daniel; Aka, Gérard; Kahn-Harari, Andrée; Aron, Astrid; Mougel, Frédéric; Bénitez, Jean-Marie; Ferrand, Bernard; Klein, Régine; Kugel, Godefroy; Nain, Nicole Le; Jacquet, Michèle

    2002-04-01

    This paper begins with a historical report of the discovery of Ca 4REO(BO 3) 3 (RECOB), a new family of nonlinear optic (NLO) materials. It presents the crystal growth and some physical characteristics related to their use in NLO applications. Then the NLO properties of GdCOB and YCOB are reviewed and the influence of some cationic substitutions is described.

  8. Demonstrations of Some Optical Properties of Liquid Crystals.

    ERIC Educational Resources Information Center

    Nicastro, Anthony J.

    1983-01-01

    Discusses several properties of liquid crystal displays. Includes instructions for demonstrating liquid crystalline phase, ordering of the long axes of molecules along one direction, and electro-optic effects. The latter is accomplished with the use of an overhead projector following preparation of a sandwich cell. (JN)

  9. Flight experiment on acousto-optic crystal growth

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Duval, Walter M. B.

    1991-01-01

    The physical vapor transport method was used for growing mercurous chloride crystals in different convective conditions. Optical homogeneity is found to be extremely dependent on convection levels. Results of numerical studies indicate that for a gravity level of 0.001 g or less the Stefan wind drives the flow and no recirculating cells are observed.

  10. Configuration of singular optical cones in gyrotropic crystals with dichroism

    SciTech Connect

    Merkulov, V. S.

    2015-02-15

    Optical conic singularities in crystals with linear dichroism and natural optical activity at the point of intersection of dispersion curves for the main refractive indices are considered. The possible existence of singularities like a nodal point, tangency point, triple point, and cusps of the first and second order is demonstrated. Forty-nine different types of irreducible fourth-order optical cones obtained by sequential bifurcations of eight main singular cones are established. The classification is based on the concept of roughness of systems depending on parameters.

  11. Optical trapping of the anisotropic crystal nanorod.

    PubMed

    Bareil, Paul B; Sheng, Yunlong

    2015-05-18

    We observed in the optical tweezers experiment that some anisotropic nanorod was stably trapped in an orientation tiled to the beam axis. We explain this trapping with the T-matrix calculation. As the vector spherical wave functions do not individually satisfy the anisotropic vector wave equation, we expand the incident and scattered fields in the isotropic buffer in terms of E→, and the internal field in the anisotropic nanoparticle in terms of D→, and use the boundary condition for the normal components of D→ to compute the T-matrix. We found that when the optical axes of an anisotropic nanorod are not aligned to the nanorod axis, the nanorod may be trapped stably at a tilted angle, under which the lateral torque equals to zero and the derivative of the torque is negative. PMID:26074566

  12. Optical diode made from a moving photonic crystal.

    PubMed

    Wang, Da-Wei; Zhou, Hai-Tao; Guo, Miao-Jun; Zhang, Jun-Xiang; Evers, Jörg; Zhu, Shi-Yao

    2013-03-01

    Optical diodes controlling the flow of light are of principal significance for optical information processing. They transmit light from an input to an output, but not in the reverse direction. This breaking of time reversal symmetry is conventionally achieved via Faraday or nonlinear effects. For applications in a quantum network, features such as the abilities of all-optical control, on-chip integration, and single-photon operation are important. Here we propose an all-optical optical diode which requires neither magnetic fields nor strong input fields. It is based on a "moving" photonic crystal generated in a three-level electromagnetically induced transparency medium in which the refractive index of a weak probe is modulated by the moving periodic intensity of a strong standing coupling field with two detuned counterpropagating components. Because of the Doppler effect, the frequency range of the crystal's band gap for the probe copropagating with the moving crystal is shifted from that for the counterpropagating probe. This mechanism is experimentally demonstrated in a room temperature Cs vapor cell. PMID:23496710

  13. Crystal Growth, Thermal, Optical, and Dielectric Properties of L-Lysine Doped Kdp Crystals

    NASA Astrophysics Data System (ADS)

    Parikh, Ketan D.; Dave, Dipak J.; Joshi, Mihir J.

    Single crystals of pure and various amount of L-lysine doped KDP crystals were grown from aqueous solution. The doping of L-lysine was confirmed by CHN analysis and FT-IR spectroscopy. Powder XRD was carried out to assess the single phase nature of the samples. The effect of doping on thermal stability of the crystals was carried out by TGA and the kinetic and thermodynamic parameters of dehydration were evaluated. It was found that as the amount of doping of amino acid, L-lysine, increased the thermal stability of the grown crystals decreased. However, the second-harmonic generation (SHG) efficiency of Nd:YAG laser and UV-vis spectroscopy studies indicated that as the L-lysine doping increased in KDP crystals the SHG efficiency and optical transmission percentage increased. The dielectric constant and the dielectric loss of L-lysine doped KDP crystals are lower than the pure KDP crystals. Hence L-lysine doped KDP crystals are found to be more beneficial from an application point of view as compared to pure KDP crystals. The results are discussed.

  14. Tunable ultracompact electro-optical photonic crystal ring resonator

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Yang

    2013-09-01

    A tunable ultracompact electro-optical photonic crystal ring resonator with high transmission is reported. The photonic crystal ring resonator is obtained by removing a ring shape of cylinders from a square lattice of dielectric cylinders in air. The transmission spectra of this ring resonator have been investigated by using the finite-difference time-domain technique. The general characteristics of the ring elements to achieve resonant tunneling are determined. By modulating the conductibility of the inner cylinders in the ring resonator, the electrical tunability of the resonant modes is observed in the transmission spectrum. The research results should open opportunities for this ring resonator as ultracompact filters, optical add-drop multiplexers, electro-optical N × N switches, and modulators.

  15. Layer matching epitaxy of NiO thin films on atomically stepped sapphire (0001) substrates

    PubMed Central

    Yamauchi, Ryosuke; Hamasaki, Yosuke; Shibuya, Takuto; Saito, Akira; Tsuchimine, Nobuo; Koyama, Koji; Matsuda, Akifumi; Yoshimoto, Mamoru

    2015-01-01

    Thin-film epitaxy is critical for investigating the original properties of materials. To obtain epitaxial films, careful consideration of the external conditions, i.e. single-crystal substrate, temperature, deposition pressure and fabrication method, is significantly important. In particular, selection of the single-crystal substrate is the first step towards fabrication of a high-quality film. Sapphire (single-crystalline α-Al2O3) is commonly used in industry as a thin-film crystal-growth substrate, and functional thin-film materials deposited on sapphire substrates have found industrial applications. However, while sapphire is a single crystal, two types of atomic planes exist in accordance with step height. Here we discuss the need to consider the lattice mismatch for each of the sapphire atomic layers. Furthermore, through cross-sectional transmission electron microscopy analysis, we demonstrate the uniepitaxial growth of cubic crystalline thin films on bistepped sapphire (0001) substrates. PMID:26402241

  16. All-optical information processing in photonic crystals

    NASA Astrophysics Data System (ADS)

    Yanik, Mehmet Fatih

    This thesis covers coherent and incoherent all-optical information processing using photonic bandgap nanostructures and microcavities. The first 3 chapters introduce all-optical bistable switching, transistor and memory elements with sub-micron scale dimensions. A strategy for large scale integration without optical isolators is also described. In chapters 4 and 5, dynamically modulated photonic crystal structures are introduced. It is shown that light pulses can be stopped and stored all-optically without requiring any coherent or resonant light-matter interaction. In chapter 6, it is shown that light pulses can be coherently time-reversed by using only index modulations and linear optics. In chapter 7, a supercomputer implementation of an object oriented finite difference time domain simulation is described to simulate photonic nanostructures with arbitrary material & geometric features.

  17. Photonic crystal composites-based wide-band optical collimator

    NASA Astrophysics Data System (ADS)

    Shi, Jinjie; Juluri, Bala Krishna; Lin, Sz-Chin Steven; Lu, Mengqian; Gao, Tieyu; Huang, Tony Jun

    2010-08-01

    Photonic crystal (PC) composites are sequenced series of PCs that feature the same periods but different filling fractions. By properly tuning the filling fractions of the individual PCs and merging the working band of each PC into a continuous frequency range, wide-band self-collimation of optical signals can be realized. The band diagrams and the equal-frequency contours of the PC structures were calculated through the plane wave expansion method and the finite-difference time-domain method was employed to simulate the propagation of electromagnetic waves through the PC structures. Our results show that while a single PC can only collimate optical waves over a narrow frequency range, a PC composite exhibits a much wider collimation band. Such a wide-band optical collimation lens can be useful in applications that demand directional optical energy flow over a long distance, such as optical imaging and biosensing.

  18. Dislocations, microhardness and optical studies on glycine potassium nitrate crystal

    NASA Astrophysics Data System (ADS)

    Chandra, Ch. Sateesh; Nagaraju, D.; Shekar, P. V. Raja; Rao, T. Tirumal; Krishna, N. Gopi

    2015-06-01

    Single crystals of glycine potassium nitrate (GPN), a semiorganic nonlinear optical crystal, of dimensions 15×12×4 mm3 were grown in a period of 10 days. The defect content present in the crystals was estimated by chemical etching technique. The results indicate that the average dislocation density is about 4.1×103/cm2. The UV-Vis. studies indicate that the crystal has a wide transmission range. The Kurtz powder test indicates that the second harmonic generation efficiency of GPN is 2.5 times that of KDP. The load-hardness curves for GPN were studied over the load range 10-100 g. The anisotropy in hardness was studied using Knoop indentation technique.

  19. Silicon dioxide nanoporous structure with liquid crystal for optical sensors

    NASA Astrophysics Data System (ADS)

    Sushynskyi, Orest; Vistak, Maria; Gotra, Zenon; Fechan, Andriy; Mikityuk, Zinoviy

    2013-05-01

    It has been studied the spectral characteristics of the porous silicon dioxide and cholesteric liquid crystal. It has been shown that doping of the EE1 cholesteric liquid crystal with Fe3O4 magnetite nanoparticles doesn't shift significantly the position of the transmittance minimum of the material. It has been found that the deformation of chiral pitch of cholesteric liquid crystal with magnetite is observed in case of doping of porous nanocomposite host with following shifting of minimum of transmittance into short wavelength direction. It has been shown that influence of carbon monoxide on optical characteristics of the cholesteric liquid crystal with magnetite can be explained by the interaction of CARBON MONOXIDE molecules with magnetite nanodopants.

  20. Complementary interference method for determining optical parameters of liquid crystals

    NASA Astrophysics Data System (ADS)

    Kowiorski, K.; Kędzierski, J.; Raszewski, Z.; Kojdecki, M. A.; Chojnowska, O.; Garbat, K.; Miszczyk, E.; Piecek, W.

    2016-04-01

    Wedge cells of small apex angle, filled with liquid crystals, were used to determining optical characteristics as functions of temperature for three liquid crystalline mixtures recently produced and a reference nematic. The interference fringes appearing in polarised monochromatic light (of sodium yellow line) normally incident on the cell were exploited to measure the ordinary and extraordinary refractive indices in the reflection mode and birefringence in the transmission mode. The measurements were repeated using Abbe's refractometer for 6CHBT as the reference to verifying the precision. Additionally the order parameter was computed from birefringence as a function of temperature. The results confirm the usefulness of the method and provide the properties of two nematic liquid crystals of small and large birefringence and one smectic liquid crystal of medium birefringence, recently produced. The experimental systems served also to investigating phase transition between the liquid crystals and the isotropic liquid at near-clearing temperature.

  1. Electro-optical field sensor using single total internal reflection in electro-optical crystals

    NASA Astrophysics Data System (ADS)

    Kijima, K.; Abe, O.; Shimizu, A.; Nakamura, T.; Kono, H.; Hagihara, S.; Torikai, E.; Hori, H.

    2015-08-01

    A novel electro-optical radio frequency field sensor with simple structure and high sensitivity is realized using single total internal reflection in electro-optical crystals. Without employing any waveguide structures, the minimum detectable electric field strength of the total internal reflection electro-optical-sensor is estimated to 86.52 dB μV/m (21.18 mV/m) at a resolution band width of 100 Hz for a short interaction length.

  2. Non-linear optical titanyl arsenates: Crystal growth and properties

    NASA Astrophysics Data System (ADS)

    Nordborg, Jenni Eva Louise

    Crystals are appreciated not only for their appearance, but also for their unique physical properties which are utilized by the photonic industry in appliances that we come across every day. An important part of enabling the technical use of optical devices is the manufacture of crystals. This dissertation deals with a specific group of materials called the potassium titanyl phosphate (KIP) family, known for their non-linear optical and ferroelectric properties. The isomorphs vary in their linear optical and dielectric properties, which can be tuned to optimize device performance by forming solid solutions of the different materials. Titanyl arsenates have a wide range of near-infrared transmission which makes them useful for tunable infrared lasers. The isomorphs examined in the present work were primarily RbTiOASO4 (RTA) and CsTiOAsO4 (CTA) together with the mixtures RbxCs 1-xTiOAsO4 (RCTA). Large-scale crystals were grown by top seeding solution growth utilizing a three-zone furnace with excellent temperature control. Sufficiently slow cooling and constant upward lifting produced crystals with large volumes useable for technical applications. Optical quality RTA crystals up to 10 x 12 x 20 mm were grown. The greater difficulty in obtaining good crystals of CTA led to the use of mixed RCTA materials. The mixing of rubidium and cesium in RCTA is more favorable to crystal growth than the single components in pure RTA and CTA. Mixed crystals are rubidium-enriched and contain only 20-30% of the cesium concentration in the flux. The cesium atoms show a preference for the larger cation site. The network structure is very little affected by the cation substitution; consequently, the non-linear optical properties of the Rb-rich isomorphic mixtures of RTA and CTA can be expected to remain intact. Crystallographic methods utilizing conventional X-ray tubes, synchrotron radiation and neutron diffraction have been employed to investigate the properties of the atomic

  3. Optical detection of sepsis markers using liquid crystal based biosensors

    NASA Astrophysics Data System (ADS)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  4. A Flexible Parameterization for Shortwave Optical Properties of Ice Crystals

    NASA Technical Reports Server (NTRS)

    VanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Cairns, Brian; Fridlind, Ann M.

    2014-01-01

    A parameterization is presented that provides extinction cross section sigma (sub e), single-scattering albedo omega, and asymmetry parameter (g) of ice crystals for any combination of volume, projected area, aspect ratio, and crystal distortion at any wavelength in the shortwave. Similar to previous parameterizations, the scheme makes use of geometric optics approximations and the observation that optical properties of complex, aggregated ice crystals can be well approximated by those of single hexagonal crystals with varying size, aspect ratio, and distortion levels. In the standard geometric optics implementation used here, sigma (sub e) is always twice the particle projected area. It is shown that omega is largely determined by the newly defined absorption size parameter and the particle aspect ratio. These dependences are parameterized using a combination of exponential, lognormal, and polynomial functions. The variation of (g) with aspect ratio and crystal distortion is parameterized for one reference wavelength using a combination of several polynomials. The dependences of g on refractive index and omega are investigated and factors are determined to scale the parameterized (g) to provide values appropriate for other wavelengths. The parameterization scheme consists of only 88 coefficients. The scheme is tested for a large variety of hexagonal crystals in several wavelength bands from 0.2 to 4 micron, revealing absolute differences with reference calculations of omega and (g) that are both generally below 0.015. Over a large variety of cloud conditions, the resulting root-mean-squared differences with reference calculations of cloud reflectance, transmittance, and absorptance are 1.4%, 1.1%, and 3.4%, respectively. Some practical applications of the parameterization in atmospheric models are highlighted.

  5. Single crystal x-ray diffraction: optical and micro hardness studies on chalcone derivative single crystal

    NASA Astrophysics Data System (ADS)

    Crasta, Vincent; Ravindrachary, V.; Bhajantri, R. F.; Naveen, S.; Shridar, M. A.; Shashidhara Prasad, J.

    2005-08-01

    1-(4-methylphenyl)-3-(4- N, N dimethyl amino phenyl)-2-propen-1-one, a chalcone derivative nonlinear optical material has been synthesized by standard method. FT-IR and NMR spectral studies have been performed to confirm the molecular structure of the synthesized compound. The single crystals up to a dimension of 13 x 9 x 3 mm3 were grown by slow evaporation method. The grown crystals were transparent in the entire visible region and absorbs in the UV-region. The refractive index has been measured using a He-Ne laser. The grown crystals have been subjected to single crystal X-ray diffraction studies to determine the crystal structure and hence the cell parameters of the crystal. From this study it is found that this compound crystallizes in orthorhombic system with a space group P212121 and corresponding lattice parameters are, a = 7.3610(13) Å, b = 11.651(2) Å, c = 17.6490(17) Å. The Kurtz powder second harmonic generation test shows that the compound is a potential candidate for Photonic application. The micro hardness test on these crystals were carried out and the load dependence hardness was observed

  6. van der Waals epitaxial growth of graphene on sapphire by chemical vapor deposition without a metal catalyst.

    PubMed

    Hwang, Jeonghyun; Kim, Moonkyung; Campbell, Dorr; Alsalman, Hussain A; Kwak, Joon Young; Shivaraman, Shriram; Woll, Arthur R; Singh, Arunima K; Hennig, Richard G; Gorantla, Sandeep; Rümmeli, Mark H; Spencer, Michael G

    2013-01-22

    van der Waals epitaxial growth of graphene on c-plane (0001) sapphire by CVD without a metal catalyst is presented. The effects of CH(4) partial pressure, growth temperature, and H(2)/CH(4) ratio were investigated and growth conditions optimized. The formation of monolayer graphene was shown by Raman spectroscopy, optical transmission, grazing incidence X-ray diffraction (GIXRD), and low voltage transmission electron microscopy (LVTEM). Electrical analysis revealed that a room temperature Hall mobility above 2000 cm(2)/V·s was achieved, and the mobility and carrier type were correlated to growth conditions. Both GIXRD and LVTEM studies confirm a dominant crystal orientation (principally graphene [10-10] || sapphire [11-20]) for about 80-90% of the material concomitant with epitaxial growth. The initial phase of the nucleation and the lateral growth from the nucleation seeds were observed using atomic force microscopy. The initial nuclei density was ~24 μm(-2), and a lateral growth rate of ~82 nm/min was determined. Density functional theory calculations reveal that the binding between graphene and sapphire is dominated by weak dispersion interactions and indicate that the epitaxial relation as observed by GIXRD is due to preferential binding of small molecules on sapphire during early stages of graphene formation. PMID:23244231

  7. Electron Beam Welder Used to Braze Sapphire to Platinum

    NASA Technical Reports Server (NTRS)

    Forsgren, Roger C.; Vannuyen, Thomas

    1998-01-01

    A new use for electron beam brazing was recently developed by NASA Lewis Research Center's Manufacturing Engineering Division. This work was done to fabricate a fiberoptic probe (developed by Sentec Corporation) that could measure high temperatures less than 600 deg C of vibrating machinery, such as in jet engine combustion research. Under normal circumstances, a sapphire fiber would be attached to platinum by a ceramic epoxy. However, no epoxies can adhere ceramic fibers to platinum under such high temperatures and vibration. Also, since sapphire and platinum have different thermal properties, the epoxy bond is subjected to creep over time. Therefore, a new method had to be developed that would permanently and reliably attach a sapphire fiber to platinum. Brazing a sapphire fiber to a platinum shell. The fiber-optic probe assembly consists of a 0.015-in.-diameter sapphire fiber attached to a 0.25-in.-long, 0.059-in.-diameter platinum shell. Because of the small size of this assembly, electron beam brazing was chosen instead of conventional vacuum brazing. The advantage of the electron beam is that it can generate a localized heat source in a vacuum. Gold reactive braze was used to join the sapphire fiber and the platinum. Consequently, the sapphire fiber was not affected by the total heat needed to braze the components together.

  8. Photonic crystal-based RGB primary colour optical filter

    NASA Astrophysics Data System (ADS)

    Singh, Brahm Raj; Rawal, Swati; Sinha, R. K.

    2016-08-01

    We have presented an RGB optical filter, based on photonic crystal (PhC) waveguides, with the hexagonal arrangement of GaP rods in air. It filters out the three primary colours of the visible range, red (R, λ = 648 nm), green (G, λ = 540 nm) and blue (B, λ = 470 nm). The plane wave expansion method is applied for estimating the dispersion curves and finite element method is utilized in examining the propagation characteristics of the designed PhC-based optical filter. Transmittance, extinction ratio and tolerance analysis have further been calculated to confirm the performance of the proposed optical filter to work in the visible range of optical spectrum and filter out the three primary colours (red, green, blue) along different output ports.

  9. Silicon single-crystal cryogenic optical resonator.

    PubMed

    Wiens, Eugen; Chen, Qun-Feng; Ernsting, Ingo; Luckmann, Heiko; Rosowski, Ulrich; Nevsky, Alexander; Schiller, Stephan

    2014-06-01

    We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 h. This stability allowed sensitive measurements of the resonator thermal expansion coefficient (α). We found that α=4.6×10(-13)  K(-1) at 1.6 K. At 16.8 K α vanishes, with a derivative equal to -6×10(-10)  K(-2). The temperature of the resonator was stabilized to a level below 10 μK for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-10(-17) level. PMID:24876023

  10. Electro-optic switching in metamaterial by liquid crystal

    NASA Astrophysics Data System (ADS)

    Lee, Yeon Ui; Kim, Junghee; Wu, Jeong Weon

    2015-12-01

    Electro-optic switching of reflection and refraction is experimentally demonstrated in metasurface liquid crystal cell. Negative metasurface is fabricated by focused-ion-beam milling, and twisted nematic cells are constructed with complementary double-split ring resonator and V-shape slot antenna metasurface. By application of an external voltage, electro-optic switchings are achieved in reflection and refraction. It has a strong implication for applications in spatial light modulation and wavelength division multiplexer/demultiplexer in a near-IR spectral range.

  11. All-optical nonlinear switching cell made of photonic crystal.

    PubMed

    Wirth Lima, A; da Silva, Marcio G; Ferreira, A C; Sombra, A S B

    2009-07-01

    We analyze and propose a directional optical coupler embedded in photonic crystal, which is driven by an external command signal. Therefore, this switching cell can work in an all-optical switch. The switching method uses a low-power external command signal, inserted in the central coupling region, which acts as another waveguide. The switching process is based on the change from the bar state to the cross state due to the external command signal. In our simulations we used the plane wave expansion method, finite-difference time-domain method, and our own binary propagation method.

  12. Extreme optical confinement in a slotted photonic crystal waveguide

    SciTech Connect

    Caër, Charles; Le Roux, Xavier; Cassan, Eric; Combrié, Sylvain De Rossi, Alfredo

    2014-09-22

    Using Optical Coherence Tomography, we measure the attenuation of slow light modes in slotted photonic crystal waveguides. When the group index is close to 20, the attenuation is below 300 dB cm{sup −1}. Here, the optical confinement in the empty slot is very strong, corresponding to an ultra-small effective cross section of 0.02 μm{sup 2}. This is nearly 10 times below the diffraction limit at λ = 1.5 μm, and it enables an effective interaction with a very small volume of functionalized matter.

  13. Nonlinear optical diglycine hydrochloride: Synthesis, crystal growth and structural characteristics

    NASA Astrophysics Data System (ADS)

    Narayana Moolya, B.; Darmaprakash, S. M.

    2006-07-01

    Diglycine hydrochloride (DGHCl), a new semiorganic nonlinear optical material with the molecular formula C 4H 11O 4Cl, was synthesized at ambient temperature. The solubility of DGHCl in water at varying temperatures was determined. Bulk single crystals were grown by the slow evaporation method at constant temperature. Powder X-ray diffraction patterns of the grown DGHCl were recorded and indexed. Functional groups present in the sample crystals were identified by FTIR spectral analysis. The chemical composition of the synthesized material was confirmed by CHN analysis. Thermal characteristics of DGHCl were determined from the TGA/DTA response curve. The Kurtz powder second harmonic generation (SHG) test showed potential for optical SHG. The UV cut-off of transmission was identified from the UV-VIS absorption spectra. The SHG of DGHCl is discussed on the basis of structural characteristics of the title compound.

  14. Optical Fluctuation of Texture in Nematic Liquid Crystal Droplets

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Jo; Back, Sang-In; Lev, Bohdan; Kim, Jong-Hyun

    2016-07-01

    We report the observation of texture of a nematic liquid crystal droplet using a high-speed camera mounted on a polarizing optical microscope. The dark crossed texture obtained by the polarizing optical microscope of a nematic liquid crystal droplet has texture wobbles, which are related to the director field fluctuation excited by thermal energy. We confirm relaxation and oscillation modes. An exact solution of the director fluctuation modes with one-constant approximation and an external electric field is proposed. The theoretical predictions of the relaxation time match with our experimental results when varying the temperature, droplet size, and electric field. Relaxation time was insensitive to the temperature, increased with radius of droplet and slightly decreased with electric field. Several oscillation modes, which have no specific trend, were also found. The external electric field freezes the oscillation modes.

  15. Rehabilitation of mandibular edentulism by single crystal sapphire implants and overdentures: 3-12 year results in 86 patients. A dual center international study.

    PubMed

    Fartash, B; Tangerud, T; Silness, J; Arvidson, K

    1996-09-01

    86 patients, in 2 Scandinavian centers, participated in a prospective study of mandibular edentulism, treated with overdentures supported by Bioceram sapphire implants. Implant success and prosthesis stability as well as parameters for peri-implant health were evaluated. Masticatory function and complications were also documented. The study began in 1991 and clinical treatment of the last patients was completed in 1991. The patients have been followed for at least 3 years, and up to 12 years. 4 patients were lost to follow-up. Of the initial 324 implants, 7 implants failed before prosthetic treatment. 3 patients lost 1 implant each within the 1st year, and 4 patients lost all 4 implants. 16 implants were lost between 36 and 42 months in function, due to lack of osseointegration and pain. The loss of implants could be attributable to an association, not statistically verified, between bone quality and anatomy, with heavy smoking as a risk factor. Based on the remaining implants, the cumulative implant success rates were 95.2%, 91.3%, 91.3%, 91.3% at 3, 5, 10 and 12 year follow-up respectively. The cumulative success rates for overdentures were 96.4%, 92.8% and 92.8% respectively, for the same follow-up periods. Indices for the health of the peri-implant mucosa disclosed no serious inflammatory reactions in the surrounding soft tissues. Patient satisfaction with this form of oral rehabilitation was high in all but 2 patients who experienced discomfort.

  16. Crystallization, Optical and Chemical Properties of Fluoride Glasses

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1985-01-01

    Fluoride glasses have great promise as infrared optical components, especially fibers, because they are transparent to 8 micrometers and higher. In order to optimize properties, different glass compositions are needed. Some are hard to form in a container, and may possibly be formable in a containerless furnace. Understanding of crystallization with and without a container could lead to glasses with optimum properties. Chemical durability (attack by water) can limit or extend the applicability of fluoride glasses. Progress to date is given.

  17. Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

    PubMed

    Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

    2014-05-01

    Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. PMID:24531108

  18. Eliminating Crystals in Non-Oxide Optical Fiber Preforms and Optical Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; LaPointe, Michael R.

    2012-01-01

    Non ]oxide fiber optics such as heavy metal fluoride and chalcogenide glasses are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. The addition of rare earths such as erbium, enable these materials to be used as fiber laser and amplifiers. Some of these glasses however are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. Previously two research teams found that microgravity suppressed crystallization in heavy metal fluoride glasses. Looking for a less expensive method to suppress crystallization, ground based research was performed utilizing an axial magnetic field. The experiments revealed identical results to those obtained via microgravity processing. This research then led to a patented process for eliminating crystals in optical fiber preforms and the resulting optical fibers. In this paper, the microgravity results will be reviewed as well as patents and papers relating to the use of magnetic fields in various material and glass processing applications. Finally our patent to eliminate crystals in non ]oxide glasses utilizing a magnetic field will be detailed.

  19. Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Gharde, Rita A.; Thakare, Sangeeta Y.

    2014-11-01

    Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

  20. Synthesis, structural, optical and thermal studies of an organic nonlinear optical 4-aminopyridinium maleate single crystal

    NASA Astrophysics Data System (ADS)

    Pandi, P.; Peramaiyan, G.; Kumar, M. Krishna; Kumar, R. Mohan; Jayavel, R.

    2012-03-01

    Synthesis and growth of a novel organic nonlinear optical (NLO) crystal of 4-aminopyridinium maleate (4APM) in larger size by the slow evaporation solution growth technique are reported. Single crystal and powder X-ray diffraction analyses reveal that 4APM crystallizes in monoclinic system with space group P21 with cell parameters a = 8.140(4) Å, b = 5.457(5) Å, c = 10.926(10) Å and volume = 481.4(7) Å3. The grown crystal has been characterized by Fourier transform infrared and UV-visible spectral analyses. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been carried out to study its thermal properties. Dielectric measurements have been carried out to study the distribution of charges within the crystal. The mechanical strength of the crystal has been studied by using Vickers' microhardness test. The etching studies have been carried out on the grown crystal. The Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal and the SHG efficiency of 4APM was found to be 4.8 times greater than that of KDP crystal.

  1. Direct observation of crystal growth from solution using optical investigation of a growing crystal face

    NASA Technical Reports Server (NTRS)

    Lal, Ravindra

    1994-01-01

    The first technical report for the period 1 Jan. 1993 till 31 Dec. 1993 for the research entitled, 'Direct observation of crystal growth from solution using Optical Investigation of a growing crystal Face' is presented. The work on the project did not start till 1 June 1993 due to the non-availability of the required personnel. The progress of the work during the period 1 June 1993 till the end of 1993 is described. Significant progress was made for testing various optical diagnostic techniques for monitoring crystal solution. Some of the techniques that are being tested are: heterodyne detection technique, in which changes in phase are measured as a interferometric function of time/crystal growth; a conventional technique, in which a fringe brightness is measured as a function of crystal growth/time; and a Mach-Zehnder interferometric technique in which a fringe brightness is measured as a function of time to obtain information on concentration changes. During the second year it will be decided to incorporate the best interferometric technique along with the ellipsometric technique, to obtain real time in-situ growth rate measurements. A laboratory mock-up of the first two techniques were made and tested.

  2. Optical apparatus using liquid crystals for shaping the spatial intensity of optical beams having designated wavelengths

    DOEpatents

    Jacobs, S.D.; Cerqua, K.A.

    1987-07-14

    The spatial intensity profile of an optical beam of designated wavelengths, such as a laser beam, is shaped (the beam is apodized) by means of cholesteric liquid crystals of opposite chirality disposed successively along the path of the beam. The crystals have curved surfaces, which may be defined by a lens which defines the thickness of the liquid crystal fluid gap in a liquid crystal cell, so as to vary the selective reflection of the designated wavelength across the aperture of the beam. In this way, a soft aperture is provided. By using tandem cell pairs having liquid crystals of opposite chirality, but of different pitch, and with lenses of different curvature, beams of different wavelengths which are projected colinearly along the path may be individually tailored in spatial intensity profile. 11 figs.

  3. Optical apparatus using liquid crystals for shaping the spatial intensity of optical beams having designated wavelengths

    DOEpatents

    Jacobs, Stephen D.; Cerqua, Kathleen A.

    1987-01-01

    The spatial intensity profile of an optical beam of designated wavelengths, such as a laser beam, is shaped (the beam is apodized) by means of cholesteric liquid crystals of opposite chirality disposed successively along the path of the beam. The crystals have curved surfaces, which may be defined by a lens which defines the thickness of the liquid crystal fluid gap in a liquid crystal cell, so as to vary the selective reflection of the designated wavelength across the aperture of the beam. In this way, a soft aperture is provided. By using tandem cell pairs having liquid crystals of opposite chirality, but of different pitch, and with lenses of different curvature, beams of different wavelengths which are projected colinearly along the path may be individually tailored in spatial intensity profile.

  4. Epitaxial growth of hexagonal silicon polytypes on sapphire

    SciTech Connect

    Pavlov, D. A.; Pirogov, A. V. Krivulin, N. O.; Bobrov, A. I.

    2015-01-15

    The formation of a single-crystal silicon polytype is observed in silicon-on-sapphire structures by high-resolution transmission electron microscopy. The appearance of inclusions with a structure different from that of diamond is attributed to the formation of strong-twinning regions and the aggregation of stacking faults, which form their own crystal structure in the crystal lattice of silicon. It is demonstrated that the given modification belongs to the 9R silicon polytype.

  5. On crystallographic orientation in crystal core optical fibers

    NASA Astrophysics Data System (ADS)

    McMillen, C.; Hawkins, T.; Foy, P.; Mulwee, D.; Kolis, J.; Stolen, R.; Rice, R.; Ballato, J.; CenterOptical Materials Science; Engineering Technologies (Comset)

    2010-07-01

    Recently developed glass-clad semiconductor core optical fibers offer potential advantages over present optical fiber materials, including greatly enhanced Raman cross-sections and extended infrared transparency. While fibers have been fabricated that exhibit a high degree of crystallinity there has not been any in-depth analysis of the nature of the crystallographic orientation of the core material relative to the fiber axes. This crystallographic analysis is of important scientific and technological value since optical fiber fabrication is a highly non-equilibrium process; consequently, achieving high degrees of crystallinity is counter-intuitive. In this work, the crystallographic orientation of germanium core optical fibers was analyzed using single crystal X-ray diffraction and electron backscatter diffraction techniques. Over nearly a 100 mm length of fiber the Ge cores were found to be polycrystalline with the <1 0 0> and <1 1 0> orientations dominant implying a dendritic growth mechanism. Single crystal regions were observed routinely in lengths greater than 8 mm with the longest being about 15 mm.

  6. Thermo-optical properties and nonlinear optical response of smectic liquid crystals containing gold nanoparticles.

    PubMed

    de Melo, P B; Nunes, A M; Omena, L; do Nascimento, S M S; da Silva, M G A; Meneghetti, M R; de Oliveira, I N

    2015-10-01

    The present work is devoted to the study of the thermo-optical and nonlinear optical properties of smectic samples containing gold nanoparticles with different shapes. By using the time-resolved Z-scan technique, we determine the effects of nanoparticle addition on the critical behavior of the thermal diffusivity and thermo-optical coefficient at the vicinity of the smectic-A-nematic phase transition. Our results reveal that introduction of gold nanoparticles affects the temperature dependence of thermo-optical parameters, due to the local distortions in the orientational order and heat generation provided by guest particles during the laser exposure. Further, we show that a nonlinear optical response may take place at temperatures where the smectic order is well established. We provide a detailed discussion of the effects associated with the introduction gold nanoparticles on the mechanisms behind the thermal transport and optical nonlinearity in liquid-crystal samples.

  7. Optical bistability in photonic crystal microrings with nonlinear dielectric materials.

    PubMed

    Ogusu, Kazuhiko; Takayama, Kosuke

    2008-05-12

    We study the linear resonance properties of several types of microrings in a two-dimensional photonic crystal (PC) consisting of a square lattice with air holes in dielectric using the plane-wave expansion method and the FDTD method. Moreover we investigate the nonlinear responses, especially optical bistability when an intense optical pulse is incident into the microrings. In this paper, Ag-As-Se chalcogenide glass is assumed as nonlinear dielectric, which has a high third-order nonlinearity. Although line-defect waveguides in an air-hole-type PC are usually multimoded, we can obtain interesting unique properties such as counter rotation of intracavity fields, transmission to all output ports, and unstable nonlinear oscillations in the multimoded PC microring. We can improve the resonance characteristics by partly introducing single-mode waveguides into microrings and can obtain stable optical bistability.

  8. Optical birefringence of liquid crystals for label-free optical biosensing diagnosis

    PubMed Central

    Nguyen, Tan Tai; Han, Gyeo-Re; Jang, Chang-Hyun; Ju, Heongkyu

    2015-01-01

    Purpose We present a polarization-sensitive optical detection platform for label-free quantitative optical biosensing diagnosis using liquid crystals (LCs). This is capable of determining quantitatively the optical birefringence of optical cells containing LCs, whose orientation depends on the immobilized biomolecules. Patients and methods This technique uses a polarization-dependent double-port detection without any polarizer at a single wavelength and removes the need of aligning optical cells of LCs in the azimuthal direction, with respect to the light path through the optical cell. Thus, this technique enables a stand-alone detection in a relatively compact format without an additional optical instrument, such as a retardation compensator, a Michael–Levy chart, and a spectrophotometer, in order to determine the optical birefringence quantitatively. Results We demonstrate that bovine serum albumin immobilized on the gold surface of the cell hybrid interfaces that support both homeotropic and planar anchoring of LCs causes optical phase retardation change which can be determined quantitatively. We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined. The estimated limit of bovine serum albumin detection is approximately 2.1 μM. Conclusion This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner. PMID:26347013

  9. Thermal and optical properties of new organic nonlinear optical single crystals

    NASA Astrophysics Data System (ADS)

    Menezes, Anthoni Praveen; Jayarama, A.

    2014-04-01

    Nonlinear optical (NLO) materials are useful in a number of industrial applications. Organic NLO single crystals of 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (4-Chloro chalcone, 4CC) and 3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (4-bromo chalcone, 4BC), having large second harmonic generation efficiency (SHG), were grown by slow evaporation technique. The thermal analysis reveals that these chalcone derivatives possess better thermal stability in comparison with urea. Both the crystals 4CC and 4BC are non-linear optically active with SHG efficiencies of 4 and 1.4 times that of urea respectively. The UV-Visible spectrum reveals that the crystals are transparent in the entire visible region. The substitution of a chloro group at the para position of the phenylene moiety is better in increasing the SHG efficiency of the crystal compared to a bromo group. Good thermal stability, optical transparency and SHG response make the crystals useful for frequency doubling of diode laser down to 435nm.

  10. Piezo-optic, photoelastic, and acousto-optic properties of SrB4O7 crystals.

    PubMed

    Mytsyk, Bohdan; Demyanyshyn, Natalia; Martynyuk-Lototska, Irina; Vlokh, Rostyslav

    2011-07-20

    On the basis of studies of the piezo-optic effect, it has been shown that SrB(4)O(7) crystals can be used as efficient acousto-optic materials in the vacuum ultraviolet spectral range. The full matrices of piezo-optic and photoelastic coefficients have been experimentally obtained for these crystals. The acousto-optic figure of merit and the diffraction efficiency have been estimated for both the visible and deep ultraviolet spectral ranges.

  11. Photonic crystal-based optical filters for operating in second and third optical fiber windows

    NASA Astrophysics Data System (ADS)

    Zamani, Mehdi

    2016-04-01

    In this paper, the filtering properties of photonic crystals (PCs) to perform narrow-channel transmission-type filters in second and third optical fiber telecommunication windows have been studied. Filtration of these zero dispersion and low-loss windows have simultaneously been established by utilizing of a triple-cavity transmission-type one-dimensional PC that provides perfect transmittances and narrow-channels at corresponding wavelengths. Such PC-based optical filter can be used in wavelength division multiplexing (WDM) optical communications systems.

  12. Crystal structure, thermal and optical properties of Benzimidazole benzimidazolium picrate crystal

    NASA Astrophysics Data System (ADS)

    Jagadesan, A.; Peramaiyan, G.; Srinivasan, T.; Kumar, R. Mohan; Arjunan, S.

    2016-02-01

    A new organic framework of benzimidazole with picric acid has been synthesized. A single crystal with a size of 38×10×4 mm3 was grown by a slow evaporation solution growth technique. X-ray diffraction study revealed that the BZP crystal belongs to triclinic system with space group P-1. High resolution X-ray diffraction study shows the absence of grain boundaries without any defects. The thermal stability and specific heat capacity of BZP were investigated by TG/DT and TG/DSC analyses. From the UV-vis-NIR spectral study, optical transmission window and band gap of BZP were found out. The nonlinear refractive index (n2) and third order susceptibility Re(χ(3)) values of BZP crystal are estimated to be 1.73×10-7 cm2/W and 1.26×10-5 esu, respectively using a Z-scan technique.

  13. Shock-induced optical emission from yttria-doped cubic zircon single crystal: crystal orientation effects

    NASA Astrophysics Data System (ADS)

    Cao, Xiuxia; Zhou, Xianming; Meng, Chuanmin

    2015-06-01

    The shock-induced optical emission from yttria (Y2O3) -doped cubic zircon single crystal (< 100 > and < 110 > crystal orientations) under the pressure range from 30 to 52 GPa was measured by the time-resolved 40-channel optical pyrometer at discrete wavelengths ranging from 400 to 800 nm. Clear periodic fluctuation was observed in spectral radiance history of < 110 > ZrO2, while a noise fluctuation was found in < 100 > ZrO2. The gray-body function was used to fit the spectral radiance histories. We found that the obtained apparent temperature varied slightly with time, but the emissivity history showed a fluctuate increase with time. Moreover, all the temperature data were independent of shock stress and were well above the calculated Lindeman melting temperature. Present result suggests that the optical emission relates to the shock-induced local hot spots, and its crystal orientation effect is attributed to the different dynamic deformation response between < 100 > and < 110 > ZrO2.

  14. Automated mineral identification algorithm using optical properties of crystals

    NASA Astrophysics Data System (ADS)

    Aligholi, Saeed; Khajavi, Reza; Razmara, Morteza

    2015-12-01

    A method has been developed to automatically characterize the type of mineral phases by means of digital image analysis using optical properties of crystals. The method relies on microscope automation, digital image acquisition, image processing and analysis. Two hundred series of digital images were taken from 45 standard thin sections using a digital camera mounted on a conventional microscope and then transmitted to a computer. CIELab color space is selected for the processing, in order to effectively employ its well-defined color difference metric for introducing appropriate color-based feature. Seven basic optical properties of minerals (A. color; B. pleochroism; C. interference color; D. birefringence; E. opacity; F. isotropy; G. extinction angle) are redefined. The Local Binary Pattern (LBP) operator and modeling texture is integrated in the Mineral Identification (MI) scheme to identify homogeneous regions in microscopic images of minerals. The accuracy of mineral identification using the method was %99, %98, %96 and %95 for biotite, hornblende, quartz and calcite minerals, respectively. The method is applicable to other minerals and phases for which individual optical properties of crystals do not provide enough discrimination between the relevant phases. On the basis of this research, it can be concluded that if the CIELab color space and the local binary pattern (LBP) are applied, it is possible to recognize the mineral samples with the accuracy of more than 98%.

  15. Liquid crystals for optical non-display applications

    NASA Astrophysics Data System (ADS)

    Lavrentovich, Oleg D.

    2012-10-01

    Liquid crystals (LCs) demonstrate a number of unusual physical properties and effects that so far has been explored mainly for LC display (LCD) applications. This presentation discusses aspects of LCs that lead to the new opportunities in non-LCD applications, such as biosensors, micro- and opto-fluidics, switchable metamaterials. A LC is a unique medium for colloidal particles as it responds to the presence of inclusions by altering the orientation of LC molecules and thus the optic axis. The effect can be used in real-time sensing of microbes, as the molecular reorientation is easily detectable by optical means. Symmetry breaking associated with director distortions around inclusions in LCs enables a new mechanism of nonlinear electrophoresis. In the liquid-crystal enabled electrophoresis (LCEEP), the velocity of particle grows with the square of the applied field. The feature allows one to use an AC driving, to create steady flows and to move uncharged particle. The trajectory of particle is not necessarily parallel to the electric field and can be controlled by the director configuration. A gradient electric field can be used to align metallic nanorods into ordered LC-like birefringent structures with spatially varying refractive index; the latter represents a switchable medium for transformation optics.

  16. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    SciTech Connect

    Awwal, A; Bauman, B; Gavel, D; Olivier, S; Jones, S; Hardy, J L; Barnes, T; Werner, J S

    2003-02-05

    Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using adaptive optics techniques, which are capable of dealing with both the standard low-order aberrations and higher-order aberrations, including coma and spherical aberration. High-order aberrations have been shown to degrade visual performance for clinical subjects in initial investigations. An adaptive optics phoropter has been designed and constructed based on a Shack-Hartmann sensor to measure the aberrations of the eye, and a liquid crystal spatial light modulator to compensate for them. This system should produce near diffraction-limited optical image quality at the retina, which will enable investigation of the psychophysical limits of human vision. This paper describes the characterization and operation of the AO phoropter with results from human subject testing.

  17. A piezoelectric single-crystal ultrasonic microactuator for driving optics.

    PubMed

    Guo, Mingsen; Dong, Shuxiang; Ren, Bo; Luo, Haosu

    2011-12-01

    At the millimeter scale, the motions or force out puts generated by conventional piezoelectric, magnetostrictive, photostrictive, or electromagnetic actuators are very limited. Here, we report a piezoelectric ultrasonic microactuator (size: 1.5 × 1.5 × 5 mm, weight: 0.1 g) made of PIN-PMN-PT single crystal. The actuator converts its high-frequency microscopic displacements (nanometer to micrometer scale) into a macro scopic, centimeter-scale linear movement of a slider via frictional force, resulting in a speed up to 50 mm/s and a very high unit volume direct driving force of 26 mN/mm(3) (which is ~100 times higher than a voice coil motor and ~4 times higher than a piezoceramic ultrasonic motor). This work shows the feasibility of using piezoelectric single-crystal-based ultrasonic microactuator for miniature drive of optics in next-generation mobiles and cameras.

  18. Photonic-crystal-based all-optical NOT logic gate.

    PubMed

    Singh, Brahm Raj; Rawal, Swati

    2015-12-01

    In the present paper, we have utilized the concept of photonic crystals for the implementation of an optical NOT gate inverter. The designed structure has a hexagonal arrangement of silicon rods in air substrate. The logic function is based on the phenomenon of the existence of the photonic bandgap and resulting guided modes in defect photonic crystal waveguides. We have plotted the transmission, extinction ratio, and tolerance analysis graphs for the structure, and it has been observed that the maximum output is obtained for a telecom wavelength of 1.554 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using the finite element method. The proposed structure is applicable for photonic integrated circuits due to its simple structure and clear operating principle.

  19. High power continuous-wave titanium:sapphire laser

    DOEpatents

    Erbert, G.V.; Bass, I.L.; Hackel, R.P.; Jenkins, S.L.; Kanz, V.K.; Paisner, J.A.

    1993-09-21

    A high-power continuous-wave laser resonator is provided, wherein first, second, third, fourth, fifth and sixth mirrors form a double-Z optical cavity. A first Ti:sapphire rod is disposed between the second and third mirrors and at the mid-point of the length of the optical cavity, and a second Ti:sapphire rod is disposed between the fourth and fifth mirrors at a quarter-length point in the optical cavity. Each Ti:sapphire rod is pumped by two counter-propagating pump beams from a pair of argon-ion lasers. For narrow band operation, a 3-plate birefringent filter and an etalon are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors are disposed between the first and second mirrors to form a triple-Z optical cavity. A third Ti:sapphire rod is disposed between the seventh and eighth mirrors at the other quarter-length point in the optical cavity, and is pumped by two counter-propagating pump beams from a third pair of argon-ion lasers. 5 figures.

  20. High power continuous-wave titanium:sapphire laser

    DOEpatents

    Erbert, Gaylen V.; Bass, Isaac L.; Hackel, Richard P.; Jenkins, Sherman L.; Kanz, Vernon K.; Paisner, Jeffrey A.

    1993-01-01

    A high-power continuous-wave laser resonator (10) is provided, wherein first, second, third, fourth, fifth and sixth mirrors (11-16) form a double-Z optical cavity. A first Ti:Sapphire rod (17) is disposed between the second and third mirrors (12,13) and at the mid-point of the length of the optical cavity, and a second Ti:Sapphire rod (18) is disposed between the fourth and fifth mirrors (14,15) at a quarter-length point in the optical cavity. Each Ti:Sapphire rod (17,18) is pumped by two counter-propagating pump beams from a pair of argon-ion lasers (21-22, 23-24). For narrow band operation, a 3-plate birefringent filter (36) and an etalon (37) are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors (101, 192) are disposed between the first and second mirrors (11, 12) to form a triple-Z optical cavity. A third Ti:Sapphire rod (103) is disposed between the seventh and eighth mirrors (101, 102) at the other quarter-length point in the optical cavity, and is pumped by two counter-propagating pump beams from a third pair of argon-ion lasers (104, 105).

  1. Optically controlled spherical liquid-crystal lens: theory and experiment

    SciTech Connect

    Gural'nik, I R; Samagin, S A

    2003-05-31

    A liquid-crystal lens with the focal distance depending on the transmitted light intensity is proposed and studied. A theoretical model is developed which adequately describes the wave-front formation by the lens. The results of visualisation of the wave-front control in a setup with crossed Polaroids and the intensity distributions, which characterise the focusing properties of the lens, are presented. To illustrate the application of the lens, an adaptive-optics system is built for stabilisation of radiation power on a 1-mm diaphragm, which reduces the power fluctuations by a factor of 30. (control of laser radiation parameters)

  2. Exploring optical mechanotransduction in fluorescent liquid crystal elastomers.

    PubMed

    Garcia-Amorós, Jaume; Bassaganyas, Sergi; Velasco, Dolores

    2016-02-21

    Carbazole-based nematic liquid single crystal elastomers switch their fluorescence mechanically on demand enabling a fast optical mechanotransduction under ambient conditions. The identification of the key factors controlling such process is of utmost importance since it might lead to a significant improvement of the transducing abilities of these smart materials. In particular, variations in the length of the fluorophore flexible spacer translates in a distinct mutual interaction between both mesogenic and fluorogenic platforms, giving rise thereby to functional materials with a significantly different mechanofluorescent behaviour. PMID:26863282

  3. Photonic crystal biosensor based on optical surface waves.

    PubMed

    Konopsky, Valery N; Karakouz, Tanya; Alieva, Elena V; Vicario, Chiara; Sekatskii, Sergey K; Dietler, Giovanni

    2013-01-01

    A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately. PMID:23429517

  4. Dispersion of the temperature-noncritical frequency conversion and birefringence in biaxial optical crystals

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2004-05-31

    Dispersion of the temperature-noncritical frequency conversion (phase matching) and birefringence in biaxial crystals is considered. The possibility of simultaneous realisation of these processes during SHG in a KTP crystal is discussed. (nonlinear optical phenomena)

  5. Optical spectroscopy of single crystals and nanoscale films of pentacene

    NASA Astrophysics Data System (ADS)

    He, Rui

    Growing interest in organic molecular semiconductors is stimulated by their promising applications in flexible devices. Transistors based on pentacene have reached device mobilities comparable to amorphous Si. This creates incentives for fundamental studies of organic molecular crystals and nanoscale structures. The research presented in this dissertation demonstrates optical spectroscopy venues for studies of organic molecular semiconductors. Pentacene single crystals and nanoscale films, reaching sub-monolayer thickness, are probed by photoluminescence and resonance Raman spectroscopies. The studies of single crystals reveal new physics linked to intrinsic and extrinsic excitations and provide benchmarks for evaluating the results in nanoscale films. By studying single crystals with different degrees of purities, I identified extrinsic luminescence bands in high quality crystals. Large resonance enhancements of Raman intensities occur when photon energies overlap intrinsic luminescence bands of free and self-trapped excitons. A four-step Raman scattering mechanism is proposed to describe the resonance processes with the self-trapped state. Photoluminescence spectra of discontinuous clusters and ultra-thin films with few monolayers in thickness reveal two fundamental excitations that are assigned to Davydov doublets of the lowest singlet exciton. The observations suggest that pentacene nanoscale films develop a structure with two molecules per unit cell. Pentacene monolayers deposited on substrates functionalized with the polymer of poly alpha-methylstyrene exhibit great lateral uniformity. These monolayers display sharp and intense free exciton luminescence bands which offer giant resonance enhancements of Raman scattering intensities. The enhancements enable the first observations of low-lying lattice modes from pentacene monolayers. The lattice modes show characteristic changes when the number of layers is increased. The low-lying lattice modes reveal inter

  6. Crystal growth and vibrational spectroscopic studies of the semiorganic non-linear optical crystal--bisthiourea magnesium sulphate.

    PubMed

    Krishnakumar, V; Ramachandraraja, C; Sundararajan, R S

    2007-09-01

    The semiorganic non-linear optical crystal bisthiourea magnesium sulphate (BTMS) was grown by slow evaporation technique using water as solvent. Vibrational spectra were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands were also assigned and discussed. The optical transmission spectral study was carried out to test the transmitting ability of the crystal in the visible range. The second harmonic generation test of BTMS revealed the non-linear nature of the crystal. The TGA/DTA curve was also recorded for the experimental crystal. PMID:17185029

  7. Optically responsive liquid crystal microfibers for display and nondisplay applications

    NASA Astrophysics Data System (ADS)

    Buyuktanir, Ebru A.; West, John L.; Frey, Margaret W.

    2011-03-01

    We demonstrate the fabrication and characterization of optically-tunable and stimuli-responsive electrospun microfibers endowed with liquid crystal (LC) functionality. The highly flexible LC microfibers are electrospun from a solution of 4- pentyl-4'-cyanobiphenyl (5CB) and polylactic acid (PLA) in chloroform/acetone solvent. In the electrospinning process, the low molecular weight 5CB phase-separates and self-assembles to form a planarly aligned nematic core within a PLA shell. Most importantly, the orientation of LC domains and, therefore, the optical properties of the 5CB/PLA fibers can be tuned by application of an external electric field. These properties of LC fibers may, in turn, be utilized to fabricate a variety of photonic textiles, and ultimately may introduce an entirely new manufacturing process where weaving will reach well beyond the roll-to-roll manufacturing envisioned for the currently emerging flexible displays printed on flexible plastic substrates.

  8. Optical continuous phase-only correlator using liquid crystal television

    NASA Astrophysics Data System (ADS)

    Sheng, Yunlong; Paul-Hus, Gilles

    1993-11-01

    We use a commercially available liquid crystal television (LCTV) for encoding real-time on- axis continuous phase-only filter (POF) in a Vander Lugt type optical correlator. We show by theory and experiments that filter coded on the LCTV with phase mismatching and coupled amplitude modulation maintains a term that is the true POF with a diffraction efficiency to about 70%, plus a zero order spot. The correlation output is a superposition of the POF correlation peak with an image of the input. The filter, referred as to the phase dominant filter, behaves like the POF with advantages of on-axis correlation: high light efficiency and utilization of all the available space bandwidth product of the LCTV. Optical experimental results are shown.

  9. Liquid crystal modulated optical amplifier for night vision imaging

    NASA Astrophysics Data System (ADS)

    Parfenov, Alexander; Xia, X. Winston; Tengara, Indra; Win, Tin; Holmstedt, Jason; Rakuljic, Neven; Aye, Tin M.; Swinney, Mathew W.; Marasco, Peter L.

    2008-08-01

    Image intensifier tubes, as part of night vision devices, have been the primary devices for the detection and amplification of near infrared light for night vision operations. In this paper, we demonstrate a novel all-optical night vision amplifier device with a potential to replace the image intensifier tube in night vision goggles. This image amplifier is based on a novel structure of semiconductor and spectrally tunable liquid crystal (LC) materials within a thin cell. The LC reacts to near-infrared (NIR) radiation but is unaffected by visible light, allowing see-through capability including visible-wavelength cockpit light. The technology is made very attractive by its high sensitivity, spatial resolution, and contrast without expensive, bulky, and heavy optics or high-voltage components.

  10. Broadband optical switch based on liquid crystal dynamic scattering.

    PubMed

    Geis, M W; Bos, P J; Liberman, V; Rothschild, M

    2016-06-27

    This work demonstrates a novel broadband optical switch, based on dynamic-scattering effect in liquid crystals (LCs). Dynamic-scattering-mode technology was developed for display applications over four decades ago, but was displaced in favor of the twisted-nematic LCs. However, with the recent development of more stable LCs, dynamic scattering provides advantages over other technologies for optical switching. We demonstrate broadband polarization-insensitive attenuation of light directly passing thought the cell by 4 to 5 orders of magnitude at 633 nm. The attenuation is accomplished by light scattering to higher angles. Switching times of 150 μs to 10% transmission have been demonstrated. No degradation of devices is found after hundreds of switching cycles. The light-rejection mechanism is due to scattering, induced by disruption of LC director orientation with dopant ion motion with an applied electric field. Angular dependence of scattering is characterized as a function of bias voltage. PMID:27410544

  11. OFT sectorization approach to analysis of optical scattering in mercurous chloride single crystals.

    PubMed

    Pata, Petr; Klima, Milos; Bednar, Jan; Janout, Petr; Barta, Cestmir; Hasal, Radek; Maresi, Luca; Grabarnik, Semen

    2015-08-10

    This paper is devoted to the application of the optical Fourier transform (OFT) for the study and evaluation of optical scattering in the latest generation of calomel single crystals ready for application in several possible devices such as IR polarizers and acoustooptic tunable filters (AOTF). There are numerous effects that are responsible for the scattering of optical wave passing through the crystal sample volume and surface layers because they affect the optical crystal quality. The scattering level is a crucial and limiting parameter in many technical applications of the evaluated crystal. The proposed approach is based upon the high dynamic range optical FT configuration, creating the amplitude spectrum in the focal plane and its spatial angular distribution analysis based on the spectrum sectorization. The optical scattering pattern was tested in nine locations within each crystal sample volume and on numerous crystal samples. The experimental results are presented and discussed.

  12. Optical and Acoustic Device Applications of Ferroelastic Crystals

    NASA Astrophysics Data System (ADS)

    Meeks, Steven Wayne

    This dissertation presents the discovery of a means of creating uniformly periodic domain gratings in a ferroelastic crystal of neodymium pentaphosphate (NPP). The uniform and non-uniform domain structures which can be created in NPP have the potential applications as tunable active gratings for lasers, tunable diffraction gratings, tunable Bragg reflection gratings, tunable acoustic filters, optical modulators, and optical domain wall memories. The interaction of optical and acoustic waves with ferroelastic domain walls in NPP is presented in detail. Acoustic amplitude reflection coefficients from a single domain wall in NPP are much larger than other ferroelastic-ferroelectrics such as gadolinium molybdate (GMO). Domain walls of NPP are used to make two demonstration acoustic devices: a tunable comb filter and a tunable delay line. The tuning process is accomplished by moving the position of the reflecting surface (the domain wall). A theory of the reflection of optical waves from NPP domain walls is discussed. The optical reflection is due to a change in the polarization of the wave, and not a change in the index, as the wave crosses the domain wall. Theoretical optical power reflection coefficients show good agreement with the experimentally measured values. The largest optical reflection coefficient of a single domain wall is at a critical angle and is 2.2% per domain wall. Techniques of injecting periodic and aperiodic domain walls into NPP are presented. The nucleation process of the uniformly periodic domain gratings in NPP is described in terms of a newly-discovered domain structure, namely the ferroelastic bubble. A ferroelastic bubble is the elastic analogue to the well-known magnetic bubble. The period of the uniformly periodic domain grating is tunable from 100 to 0.5 microns and the grating period may be tuned relatively rapidly. The Bragg efficiency of these tunable gratings is 77% for an uncoated crystal. Several demonstration devices which use

  13. Optical Properties of Small Ice Crystals with Black Carbon Inclusions

    NASA Astrophysics Data System (ADS)

    Yang, X.; Geier, M.; Arienti, M.

    2013-12-01

    The optical properties of ice crystals play a fundamental role in modeling atmospheric radiation and hydrological cycle, which are critical in monitoring climate change. While Black Carbon (BC) is recognized as the dominant absorber with positive radiative forcing (warming) (Ramanathan & Carmichael, 2008), in-situ observations (Cappa, et al, 2012) indicate that the characterization of the mixing state of BC with ice crystals and other non-BC particles in global climate models (Ghan & Schwartz, 2007) needs further investigation. The limitation in the available mixing models is due to the drastically different absorbing properties of BC compared to other aerosols. We explore the scattering properties of ice crystals (in shapes commonly found in cirrus clouds and contrails - Yang, et al. 2012) with the inclusion of BC particles. The Discrete Dipole Approximation (DDA) (Yurkin & Hoekstra, 2011) is utilized to directly calculate the optical properties of the crystals with multiple BC inclusions, modeled as a distribution of spheres. The results are then compared with the most popular models of internal and external mixing (Liou, et al. 2011). The DDA calculations are carried out over a broad range of BC particle sizes and volume fractions within the crystal at the 532 nm wavelength and for ice crystals smaller than 50 μm. The computationally intensive database generated in this study is critical for understanding the effect of different types of BC inclusions on the atmosphere radiative forcing. Examples will be discussed to illustrate the modification of BC optical properties by encapsulation in ice crystals and how the parameterization of the BC mixing state in global climate models can be improved. Acknowledgements Support by Sandia National Laboratories' LDRD (Laboratory Directed Research and Development) is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of

  14. Increase of bulk optical damage threshold fluences of KDP crystals by laser irradiation and heat treatment

    DOEpatents

    Swain, J.E.; Stokowski, S.E.; Milam, D.; Kennedy, G.C.; Rainer, F.

    1982-07-07

    The bulk optical damage threshold fluence of potassium dihydrogen phosphate (KDP) crystals is increased by irradiating the crystals with laser pulses of duration 1 to 20 nanoseconds of increasing fluence, below the optical damage threshold fluence for untreated crystals, or by baking the crystals for times of the order of 24 hours at temperatures of 110 to 165/sup 0/C, or by a combination of laser irradiation and baking.

  15. Synthesis, Growth, Spectral and Optical Properties of Glycinyl Urea Single Crystal

    SciTech Connect

    Shanthi, N. Theresita; Selvarajan, P.; Rose, A. S. J. Lucia

    2011-10-20

    Single crystals of Glycinyl Urea were grown from aqueous solution by slow evaporation technique at room temperature. The cell parameters of the grown crystals were estimated by Single X-ray diffraction studies. The functional groups present in the grown crystals were ascertained using FTIR spectrum analysis. UV-visible transmittance spectrum was recorded to study the optical transparency of the grown crystal. The non-linear optical property has been tested by Kurtz powder technique.

  16. Doped sillenite crystals applicable for fiber-optic magnetic sensors

    NASA Astrophysics Data System (ADS)

    Tassev, V.; Diankov, G.; Gospodinov, M.

    1996-11-01

    The spectral dependencies of the optical rotatory power (ORP-ϱ) and the Verdet coefficient ( V) of undoped and Fe- and Cr-doped Bi 12SiO 20 ( BSO) crystals are studied in the spectral range of 440-800 nm. The results show that Cr decreases ϱ about 4-5% in the range 600-700 nm, but below 560 nm ϱ strongly increases up to 180-200% compared to the ORP of undoped BSO, which could be related to the earlier observed absorption spectra. Like the ORP, the values of V are lower by about 1-3% at 700-600 nm, whereas below 590 nm V increases about 2%. The influence of Fe on ϱ and V strongly depends on the dopant concentration. For example, at larger concentrations (2.2 mol%) ϱ and V decrease up to 4% and 12%, respectively, whereas at 0.9 mol% Fe ϱ and V increase 3% and 9%, respectively. The influence of the annealung and the illumination on the gyrotropy of undoped BSO are also studied. Some assumption about the nature of the sillenite optical and magneto-optical rotation are made. The possibilities to use these materials for fiber optic magnetic field sensors or to improve their characteristics for photorefractive applications are discussed, too.

  17. Fabrication and optical transmission characteristics of polymers woodpile photonic crystal structures with different crystal planes

    NASA Astrophysics Data System (ADS)

    Chen, Ling-Jing; Dong, Xian-Zi; Zhao, Yuan-Yuan; Zhang, Yong-Liang; Liu, Jie; Zheng, Mei-Ling; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2015-10-01

    The photonic band gap effect which originates from the translational invariance of the periodic lattice of dielectrics has been widely applied in the technical applications of microwave, telecommunication and visible wavelengths. Among the various examples, polymers based three dimensional (3D) photonic crystals (PhCs) have attracted considerable interest because they can be easily fabricated by femo-second (fs) ultrafast laser direct writing (DLW) method. However, it is difficult to realize complete band gap in polymers PhCs due to the low index contrast between polymers and air. Here, we report the design and experimental realization of light's nonreciprocal propagation in woodpile PhCs fabricated with DLW method. Firstly, we fabricated several polymers woodpile PhCs on glass substrate with different crystal planes. The Fourier transform infrared spectroscopy (FTIR) measurements are in agreement with the theoretical predictions, which proves the validity and the accuracy of our DLW method. Further measurements of the transmission spectra with respect to the incident angle reveal that the surface crystal planes and incident wave vectors play important roles in the optical response. Furthermore, we designed and fabricated a 30° PhC wedge. And we find nonreciprocal transmission effect between the forward and backward waves, resulting from the nonsymmetrical refraction of the light in different planes. Our results may find potential applications in future 3D photonic integrated circuits and pave the way for the fabrication of other photonic and optical devices with DLW method.

  18. Control of initial bow of sapphire substrates for III-nitride epitaxy by internally focused laser processing

    NASA Astrophysics Data System (ADS)

    Aida, Hideo; Aota, Natsuko; Takeda, Hidetoshi; Koyama, Koji

    2012-12-01

    Processing by a laser beam focused within the substrate is used to control the initial bowing of sapphire substrates for III-nitride epitaxy. The process modifies the sapphire crystallinity at and near the focal area from single crystal to an amorphous phase. As volume expansion occurs inside the sapphire, strain is generated and, consequently, changes in the bowing. By controlling the focal depth and process pitch, we demonstrate a ˜250 μm pre-bowed sapphire substrate while only ±15 μm of bowing control is possible with a regular wafering process. We also demonstrate epitaxial growth of III-nitride on the pre-bowed sapphire substrates by metal organic chemical vapor deposition (MOCVD), which suggests an enlargement for the process window for III-nitride epitaxy on sapphire substrate. It is also shown that the pre-bowing by laser treatment functions to improve the crystal quality of grown III-nitride films.

  19. Investigation of organic nonlinear optical crystals for harmonic frequency conversion and electro-optics. Final technical report

    SciTech Connect

    1998-01-01

    The authors are conducting a detailed study of the crystal growth of different organic materials and their physical, optical and morphological properties. The crystals are grown by a novel solution crystal growth technique developed by the principal investigator at Alabama A and M University (AAMU). The studies included the measurement of solubility of organic NLO materials in different solvents, growth of crystals by solution growth technique, and the characterization of optical properties and damage threshold of crystals for high power laser applications. Two different NLO crystals of 4-Aminobenzophenone (ABP) and 3-methoxy-4-hydroxy-benzaldehyde (MHBA) were investigated during the course of this investigation. A paper on ABP crystals was published in Journal of Crystal Growth in 1997.

  20. Lasing and waveguiding in smectic A liquid crystal optical fibers.

    PubMed

    Peddireddy, Karthik; Jampani, V S R; Thutupalli, Shashi; Herminghaus, Stephan; Bahr, Christian; Muševič, Igor

    2013-12-16

    We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of smectic-A liquid crystal microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. They are characterized by a line topological defect in the core of the fiber with an optical axis pointing from the defect core towards the surface. We demonstrate guiding of light along the fiber and Whispering Gallery Mode (WGM) lasing in a plane perpendicular to the fiber. The light guiding as well as the lasing threshold are significantly dependent on the polarization of the excitation beam. The observed threshold for WGM lasing is very low (≈ 75μJ/cm(2)) when the pump beam polarization is perpendicular to the direction of the laser dye alignment and is similar to the lasing threshold in nematic droplets. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits. PMID:24514602

  1. Lasing and waveguiding in smectic A liquid crystal optical fibers.

    PubMed

    Peddireddy, Karthik; Jampani, V S R; Thutupalli, Shashi; Herminghaus, Stephan; Bahr, Christian; Muševič, Igor

    2013-12-16

    We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of smectic-A liquid crystal microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. They are characterized by a line topological defect in the core of the fiber with an optical axis pointing from the defect core towards the surface. We demonstrate guiding of light along the fiber and Whispering Gallery Mode (WGM) lasing in a plane perpendicular to the fiber. The light guiding as well as the lasing threshold are significantly dependent on the polarization of the excitation beam. The observed threshold for WGM lasing is very low (≈ 75μJ/cm(2)) when the pump beam polarization is perpendicular to the direction of the laser dye alignment and is similar to the lasing threshold in nematic droplets. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits.

  2. Single layer liquid crystal optically addressed spatial light modulators

    NASA Astrophysics Data System (ADS)

    Collings, N.; Trushkevych, O.; Crossland, W. A.; Wilkinson, T. D.

    2006-08-01

    Traditionally, the light receptor and light modulation aspects of Optically Addressed Spatial Light Modulators (OASLMs) occur in separate layers. Due to the progress that has been made in the study of nonlinearity in liquid crystal cell doped with chromophores in the past 20 years, it is appropriate to consider in what ways they themselves may be useful as OASLMs. The light reception and modulation aspects coexist within the same layer in these cells. We have been studying a variety of chromophore-doped systems (azo and anthraquinone dyes, buckminsterfullerene, and carbon nanotubes) over the past four years. Dynamic holographic grating formation is observed under conditions of low power laser light both with and without external fields. The majority of the samples are planar aligned and normal incidence of light can be used. They possess very good lifetime stability and no degradation even under high write light intensities. We understand how to avoid permanent recordings using appropriate alignment surfaces. This is important in OASLM applications where real-time updating of written information is required (dynamic holography, all-optical switching). The resolution of the devices is superior to the thickness of the liquid crystal layer, and comparable to the best traditional OASLMs. We are currently working on understanding the dynamics in order to address the issue of speed of response. The report will include latest results on diffraction efficiency from our OASLM characterization set-up.

  3. Highly luminescent garnets for magneto-optical photonic crystals

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Khartsev, S. I.

    2009-09-01

    We compare luminescent properties of several Er-doped garnets as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals. Pulsed laser deposited La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, and rf-magnetron sputtered Bi3Fe5O12 were chosen to host Er3+ ions on dodecahedral lattice sites. Er substituents with the concentration of 0.5 at. % (0.1 garnet formula units) do not decrease giant Faraday rotation in Bi2.9Er0.1Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching almost 6 ms in Gd2.9Er0.1Ga5O12. We conclude Er substitution in gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

  4. Chiral multichromic single crystals for optical devices (LDRD 99406).

    SciTech Connect

    Kemp, Richard Alan; Felix, Ana M. (University of New Mexico, Albuquerque, NM)

    2006-12-01

    This report summarizes our findings during the study of a novel system that yields multi-colored materials as products. This system is quite unusual as it leads to multi-chromic behavior in single crystals, where one would expect that only a single color would exist. We have speculated that these novel solids might play a role in materials applications such as non-linear optics, liquid crystal displays, piezoelectric devices, and other similar applications. The system examined consisted of a main-group alkyl compound (a p block element such as gallium or aluminum) complexed with various organic di-imines. The di-imines had substituents of two types--either alkyl or aromatic groups attached to the nitrogen atoms. We observed that single crystals, characterized by X-ray crystallography, were obtained in most cases. Our research during January-July, 2006, was geared towards understanding the factors leading to the multi-chromic nature of the complexes. The main possibilities put forth initially considered (a) the chiral nature of the main group metal, (b) possible reduction of the metal to a lower-valent, radical state, (c) the nature of the ligand(s) attached to the main group metal, and (d) possible degradation products of the ligand leading to highly-colored products. The work carried out indicates that the most likely explanation considered involves degradation of the aromatic ligands (a combination of (c) and (d)), as the experiments performed can clearly rule out (a) and (b).

  5. Crystal structure, growth and characterizations of a novel organic third-order nonlinear optical crystal: guanidinium cinnamate

    NASA Astrophysics Data System (ADS)

    Dhavamurthy, M.; Raja, R.; Syed Suresh Babu, K.; Mohan, R.

    2016-08-01

    Guanidinium cinnamate (GUCN), a single crystal, was grown by slow evaporation technique. Single-crystal X-ray diffraction study revealed that GUCN crystal belongs to monoclinic crystal system with the space group P21/c. Thermal studies revealed that the GUCN is thermally stable up to 238 °C. The optical transmittance studies were carried out for the crystal, and the lower cutoff wavelength of the grown crystal was observed at 322 nm. The luminescent study showed that the GUCN crystal has high degree of luminescence. Third-order nonlinear refractive index n2, nonlinear absorption coefficient β and susceptibility χ(3) parameters were estimated by Z-scan technique. The four independent tensor coefficients ɛ11, ɛ22, ɛ33 and ɛ13 of dielectric permittivities for monoclinic GUCN were calculated. The mechanical properties of the grown crystals were studied using Vickers micro-hardness tester at different planes.

  6. Synthesis, linear optical, non-linear optical, thermal and mechanical characterizations of dye-doped semi-organic NLO crystals

    NASA Astrophysics Data System (ADS)

    Sesha Bamini, N.; Vidyalakshmy, Y.; Choedak, Tenzin; Kejalakshmy, N.; Muthukrishnan, P.; Ancy, C. J.

    2015-06-01

    Organic laser dyes Coumarin 485, Coumarin 540 and Rhodamine 590 Chloride were used to dope potassium acid phthalate crystals (KAP). Dye-doped KAP crystals with different dye concentrations such as 0.01 mM, 0.03 mM, 0.05 mM, 0.07 mM and 0.09 mM (in the KAP growth solution) were grown. The linear optical, non-linear optical, mechanical and thermal characterizations of dye-doped KAP crystals were studied and compared to understand the effect of dye and dye concentration on the KAP crystal. Absorption and emission studies of KAP and dye-doped KAP single crystals indicated the inclusion of the dye into the KAP crystal lattice. The effect of dye and its concentration on the SHG efficiency of the KAP crystal was studied using the Kurtz and Perry powder technique. It was observed that the absorption maximum wavelength and concentration of the dye used for doping the KAP single crystal decided the SHG efficiency of the dye-doped KAP single crystals. The mechanical hardness of the dye-doped and undoped (pure) KAP single crystals were studied using the Vickner’s microhardness test. It was observed that doping the KAP crystals with the laser dyes changed them from softer material to harder material. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with laser dyes.

  7. Optical Basicity and Nepheline Crystallization in High Alumina Glasses

    SciTech Connect

    Rodriguez, Carmen P.; McCloy, John S.; Schweiger, M. J.; Crum, Jarrod V.; Winschell, Abigail E.

    2011-02-25

    The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.

  8. Spherical-sapphire-based whispering gallery mode resonator thermometer

    NASA Astrophysics Data System (ADS)

    Yu, Lili; Fernicola, V.

    2012-09-01

    A novel microwave whispering gallery mode (WGM) resonator based on a spherical sapphire crystal was developed at INRIM and its use as a thermometer was tested. The temperature dependence of the WGM frequencies was studied and the most promising resonance near to 13.6 GHz, with a loaded quality factor as large as 82 000, was carefully investigated. Its potential use in thermometry was evaluated through a study of its main metrological characteristics, such as the temperature sensitivity, the frequency stability, the repeatability, and the resolution at several temperatures over the temperature range -40 °C to 85 °C. Finally, the INRIM spherical sapphire thermometer was compared with the NIST SWGT, a dielectric thermometer based on a cylindrical sapphire resonator [V. B. Braginsky, V. S. Ilchenko, and Kh. S. Bagdassarov, Phys. Lett. A 120(3), 300 (1987), 10.1016/0375-9601(87)90676-1].

  9. All-optical signal processing at 10 GHz using a photonic crystal molecule

    SciTech Connect

    Combrié, Sylvain; Lehoucq, Gaëlle; Junay, Alexandra; De Rossi, Alfredo; Malaguti, Stefania; Bellanca, Gaetano; Trillo, Stefano; Ménager, Loic; Peter Reithmaier, Johann

    2013-11-04

    We report on 10 GHz operation of an all-optical gate based on an Indium Phosphide Photonic Crystal Molecule. Wavelength conversion and all-optical mixing of microwave signals are demonstrated using the 2 mW output of a mode locked diode laser. The spectral separation of the optical pump and signal is crucial in suppressing optical cross-talk.

  10. Growth and characterization of a new nonlinear optical organic crystal: 2,4,6-Trimethylacetanilide

    NASA Astrophysics Data System (ADS)

    Upadhyaya, V.; Prabhu, Sharada G.

    2015-09-01

    A new nonlinear optical organic material, 2,4,6-trimethylacetanilide (246TMAA), also known as N-[2,4,6- trimethylphenyl]acetamide, has been synthesized and grown as a single crystal by the slow evaporation technique by organic solvents. The grown crystals have been characterized by morphology study. The crystals are prismatic. Surface examination shows granular dendritic pattern in optical micrograph. The Scanning Electron Micrograph shows the layered growth of the crystal. The Differential Scanning Calorimeter plot shows no phase change until melting point (219°C). The density of the crystals is 1.1g/cc and the crystals are soft. The crystals are transparent in the visible region and in the ultra-violet region till 280 nm. 246TMAA crystallizes with 2 molecules in a monoclinic unit cell in the noncentrosymmetric point group m, space group Pn. Refractive indices of this optically biaxial crystal along the three crystallophysical axes have been measured at 633 nm. The optical second harmonic generation efficiency of the crystal at 1064 nm is about half that of the urea crystal, measured by powder method using Nd:YAG laser. The results show that the 246TMAA crystal can efficiently be used for up-conversion of infrared radiation into visible green light. The powder X-ray diffraction spectrum of the crystal has been obtained.

  11. Characterization of refractory materials using sapphire strain gages

    SciTech Connect

    Tran, T.A.; Greene, J.A.; Alcock, M.A.

    1995-12-31

    A high-temperature sapphire strain gage based on the optical fiber extrinsic Fizeau interferometric sensor (EFI) was used to measure strain on a compressive loaded silicon carbide rod at a temperature of 1100{degrees}C. Experimental strain sensitivities on the order of 1 {mu}{epsilon} were obtained.

  12. Growth, structure and optical properties of nonlinear optical crystal BaZnBO3F

    NASA Astrophysics Data System (ADS)

    Xia, Mingjun; Li, R. K.

    2016-01-01

    Nonlinear optical (NLO) crystal BaZnBO3F (BZBF) with the size of about 20×20×0.5 mm3 is obtained from BaF2-NaF flux, and single crystal X-ray diffraction reveals that it belongs to space group P 6 ̅ with cell parameters of a=5.1045(6) Å, c=4.3116(10) Å and Z=1. In the structure of BZBF, the BO3 planar triangles are interconnected through O atoms from ZnO3F2 trigonal bipyramid to form (Zn3B3O6F6) twelve-membered rings (12-MRs), then the layers which are built with condensation from 12-MRs at ab plane, are further linked by the apical F from ZnO3F2 to form three dimensional framework along the c direction. The title crystal exhibits high transmittance in the range of 300-3000 nm with a UV transmission cutoff at 223 nm according to transmission spectra. Powder SHG tests indicate that the effective NLO coefficient of BZBF crystal is about 2.8 times that of KH2PO4 (KDP) crystal due to perfect alignment of the BO3 groups.

  13. Laser damage resistant anti-reflection microstructures in Raytheon ceramic YAG, sapphire, ALON, and quartz

    NASA Astrophysics Data System (ADS)

    Hobbs, Douglas S.; MacLeod, Bruce D.; Sabatino, Ernest, III; Hartnett, Thomas M.; Gentilman, Richard L.

    2011-06-01

    A study of the laser induced damage threshold (LiDT) of anti-reflection (AR) microstructures (ARMs) built in the end facets of metal ion doped yttrium aluminum garnet (YAG) laser gain material, has been conducted. Test samples of undoped and ytterbium-doped polycrystalline YAG produced by Raytheon Company were processed with ARMs in one surface and subjected to standardized pulsed LiDT testing at the near-infrared (NIR) wavelength of 1064nm. As received YAG samples with a simple commercial polish were also submitted to the damage tests for comparison, along with YAG samples that were treated with a single layer thin-film AR coating designed for maximum transmission at 1064nm. Additional samples of single crystal sapphire and quartz, and polycrystalline ALONTM windows were prepared with thin-film AR coatings and ARMs textures to expand the 1064nm laser damage testing to other important NIR transmitting materials. It was found that the pulsed laser damage resistance of ARMs textured ceramic YAG windows is 11 J/cm2, a value that is 43% higher than untreated ceramic YAG windows, suggesting that ARMs fabrication removed residual sub-surface damage, a factor that has been shown to be important for increasing the damage resistance of an optic. This conclusion is also supported by the high damage threshold values found with the single layer AR coatings on ceramic YAG where the coatings may have shielded the sub-surface polishing damage. Testing results for the highly polished sapphire windows also support the notion that better surface preparation produces higher damage resistance. The damage threshold for untreated sapphire windows exceeded 32 J/cm2 for one sample with an average of 27.5 J/cm2 for the two samples tested. The ARMs-treated sapphire windows had similar damage thresholds as the untreated material, averaging 24.9 J/cm2, a value 1.5 to 2 times higher than the damage threshold of the thin film AR coated sapphire windows.

  14. Nonlinear optics in high refractive index contrast photonic crystal microcavities

    NASA Astrophysics Data System (ADS)

    Cowan, Allan Ralph

    2005-07-01

    This thesis describes theoretical and experimental research on the nonlinear response of high refractive index contrast (HRIC) optical microcavities. An intuitive, numerically efficient model of second harmonic reflection from two dimensional (2D), planar photonic crystals made of sub-wavelength thick, non-centrosymmetric semiconductors is developed. It predicts that appropriate 2D texture can result in orders of magnitude enhancement of the reflected second order signal when harmonic plane waves are used to excite leaky photonic crystal eigenmodes. Local field enhancement in the textured slab, and other physical processes responsible for these enhancements are explained. A different formalism is developed to treat the Kerr-related bistable response of a 3D microcavity coupled to a single mode waveguide. This model predicts that optical bistability should be observed using only milliwatts of power to excite a cavity fabricated in Al0.18 Ga0.82As, having a quality factor of Q = 4000 and a mode volume of 0.05 mum 3. Two-photon absorption is shown to only slightly hinder the performance in Al0.18Ga0.82 As. By including nonresonant downstream reflections in the model, novel hysteresis loops are predicted, and their stability is analyzed. A coupled waveguide-microcavity structure is fabricated by selectively cladding a silicon ridge-Bragg grating waveguide with photoresist. Three-dimensionally localized optical modes are realized with Q values ranging from 200 to 1200, at ˜1.5 mum. Using 100 fs pulses, the transmission spectra of these structures is studied as a function of input power. The output power saturates when the cavity mode and pulse centre frequencies are resonant, and the output exhibits superlinear growth when they are appropriately detuned. These results are explained in terms of the filtering action of the microcavity on the nonlinear spectral distortion of the input pulse as it propagates through the waveguide. PbSe nanocrystals are deposited on a

  15. Miniature Sapphire Acoustic Resonator - MSAR

    NASA Technical Reports Server (NTRS)

    Wang, Rabi T.; Tjoelker, Robert L.

    2011-01-01

    A room temperature sapphire acoustics resonator incorporated into an oscillator represents a possible opportunity to improve on quartz ultrastable oscillator (USO) performance, which has been a staple for NASA missions since the inception of spaceflight. Where quartz technology is very mature and shows a performance improvement of perhaps 1 dB/decade, these sapphire acoustic resonators when integrated with matured quartz electronics could achieve a frequency stability improvement of 10 dB or more. As quartz oscillators are an essential element of nearly all types of frequency standards and reference systems, the success of MSAR would advance the development of frequency standards and systems for both groundbased and flight-based projects. Current quartz oscillator technology is limited by quartz mechanical Q. With a possible improvement of more than x 10 Q with sapphire acoustic modes, the stability limit of current quartz oscillators may be improved tenfold, to 10(exp -14) at 1 second. The electromagnetic modes of sapphire that were previously developed at JPL require cryogenic temperatures to achieve the high Q levels needed to achieve this stability level. However sapphire fs acoustic modes, which have not been used before in a high-stability oscillator, indicate the required Q values (as high as Q = 10(exp 8)) may be achieved at room temperature in the kHz range. Even though sapphire is not piezoelectric, such a high Q should allow electrostatic excitation of the acoustic modes with a combination of DC and AC voltages across a small sapphire disk (approximately equal to l mm thick). The first evaluations under this task will test predictions of an estimated input impedance of 10 kilohms at Q = 10(exp 8), and explore the Q values that can be realized in a smaller resonator, which has not been previously tested for acoustic modes. This initial Q measurement and excitation demonstration can be viewed similar to a transducer converting electrical energy to

  16. Development of optical systems. [holographic technique for monitoring crystal growth

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1995-01-01

    Several key aspects of multi-color holography and laser speckle technique to study holographic reconstructions are considered in the report. Holographic fringe contrast in two-color holography in the presence of a fluid cell in the object beam is discussed in detail. A specific example of triglycine sulfate crystal growth is also considered. A breadboard design using fiber optics and diode lasers for three-color holography for fluid experiments is presented. A possible role of multi-color holography in various new applications is summarized. Finally, the use of a a laser speckle technique is demonstrated for the study of holographic reconstructions. The demonstration is performed using a Spacelab 3 hologram.

  17. Optical Tamm states in one-dimensional superconducting photonic crystal

    NASA Astrophysics Data System (ADS)

    El Abouti, O.; El Boudouti, E. H.; El Hassouani, Y.; Noual, A.; Djafari-Rouhani, B.

    2016-08-01

    In this study, we investigate localized and resonant optical waves associated with a semi-infinite superlattice made out of superconductor-dielectric bilayers and terminated with a cap layer. Both transverse electric and transverse magnetic waves are considered. These surface modes are analogous to the so-called Tamm states associated with electronic states found at the surface of materials. The surface guided modes induced by the cap layer strongly depend on whether the superlattice ends with a superconductor or a dielectric layer, the thickness of the surface layer, the temperature of the superconductor layer as well as on the polarization of the waves. Different kinds of surface modes are found and their properties examined. These structures can be used to realize the highly sensitive photonic crystal sensors.

  18. Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure

    NASA Astrophysics Data System (ADS)

    Wu, Zheng; Chen, Juguang; Ji, Mengxi; Huang, Qingzhong; Xia, Jinsong; Wu, Ying; Wang, Yi

    2015-11-01

    An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (QL) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.

  19. Path to meter class single crystal silicon (SCSi) space optics

    NASA Astrophysics Data System (ADS)

    McCarter, Douglas R.

    2012-03-01

    With the global financial crisis affecting funding for space systems development, customers are calling for lower cost systems. Yet, at the same time, these lower cost systems must have increased thermal response to operational environments and load survivability. We submit that single crystal silicon (SCSi) meets both of these requirements. This paper will highlight some key SCSi material properties, discuss the opportunities that led to the development of McCarter processing methods, and present the latest steps in the manufacturing path of McCarter Mirrors using SCSi, GFB (glass frit bonding) and MSF (McCarter super finish), including the concept drawing of a one meter SCSi lightweight mirror, which together sets up the last step toward a lower cost, high performing one meter SCSi space optic.

  20. Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure

    SciTech Connect

    Wu, Zheng; Chen, Juguang; Ji, Mengxi; Huang, Qingzhong; Xia, Jinsong; Wang, Yi E-mail: ywangwnlo@mail.hust.edu.cn; Wu, Ying E-mail: ywangwnlo@mail.hust.edu.cn

    2015-11-30

    An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (Q{sub L}) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.

  1. Ultrafast optical switching using photonic molecules in photonic crystal waveguides.

    PubMed

    Zhao, Yanhui; Qian, Chenjiang; Qiu, Kangsheng; Gao, Yunan; Xu, Xiulai

    2015-04-01

    We study the coupling between photonic molecules and waveguides in photonic crystal slab structures using finite-difference time-domain method and coupled mode theory. In a photonic molecule with two cavities, the coupling of cavity modes results in two super-modes with symmetric and anti-symmetric field distributions. When two super-modes are excited simultaneously, the energy of electric field oscillates between the two cavities. To excite and probe the energy oscillation, we integrate photonic molecule with two photonic crystal waveguides. In coupled structure, we find that the quality factors of two super-modes might be different because of different field distributions of super-modes. After optimizing the radii of air holes between two cavities of photonic molecule, nearly equal quality factors of two super-modes are achieved, and coupling strengths between the waveguide modes and two super-modes are almost the same. In this case, complete energy oscillations between two cavities can be obtained with a pumping source in one waveguide, which can be read out by another waveguide. Finally, we demonstrate that the designed structure can be used for ultrafast optical switching with a time scale of a few picoseconds.

  2. Optical switch based on the electrically controlled liquid crystal interface.

    PubMed

    Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

    2015-06-01

    The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically. PMID:26192675

  3. Dynamic and reversible organization of zeolite L crystals induced by holographic optical tweezers.

    PubMed

    Woerdemann, Mike; Gläsener, Stefan; Hörner, Florian; Devaux, André; De Cola, Luisa; Denz, Cornelia

    2010-10-01

    Organization and patterning of zeolite L crystals with their unique properties such as their one-dimensional nano channel system is of highest topical interest with various applications in many areas of science. We demonstrate full three-dimensional optical control of single zeolite L crystals and for the first time fully reversible, dynamic organization of a multitude of individually controlled zeolite L crystals.

  4. Optical switching of near infrared light transmission in metamaterial-liquid crystal cell structure.

    PubMed

    Kang, Boyoung; Woo, J H; Choi, E; Lee, Hyun-Hee; Kim, E S; Kim, J; Hwang, Tae-Jong; Park, Young-Soon; Kim, D H; Wu, J W

    2010-08-01

    A metamaterial-liquid crystal cell structure is fabricated with the metamaterial as one of the liquid crystal alignment layers. Nano-sized double-split ring resonator in the metamaterial accommodates two distinct resonances in the near infrared regime. By adopting an azo-nematic liquid crystal in a twisted nematic liquid crystal cell structure, a photo-isomerization process is utilized to achieve an optical switching of light transmissions between two resonances. A single device of the metamaterial-liquid crystal cell structure has a potential application in the photonic switching in optical fiber telecommunications.

  5. Optical switching of near infrared light transmission in metamaterial-liquid crystal cell structure.

    PubMed

    Kang, Boyoung; Woo, J H; Choi, E; Lee, Hyun-Hee; Kim, E S; Kim, J; Hwang, Tae-Jong; Park, Young-Soon; Kim, D H; Wu, J W

    2010-08-01

    A metamaterial-liquid crystal cell structure is fabricated with the metamaterial as one of the liquid crystal alignment layers. Nano-sized double-split ring resonator in the metamaterial accommodates two distinct resonances in the near infrared regime. By adopting an azo-nematic liquid crystal in a twisted nematic liquid crystal cell structure, a photo-isomerization process is utilized to achieve an optical switching of light transmissions between two resonances. A single device of the metamaterial-liquid crystal cell structure has a potential application in the photonic switching in optical fiber telecommunications. PMID:20721037

  6. Optical and Spectral Studies on β Alanine Metal Halide Hybrid Crystals

    NASA Astrophysics Data System (ADS)

    Sweetlin, M. Daniel; Selvarajan, P.; Perumal, S.; Ramalingom, S.

    2011-10-01

    We have synthesized and grown β alanine metal halide hybrid crystals viz. β alanine cadmium chloride (BACC), an amino acid transition metal halide complex crystal and β alanine potassium chloride (BAPC), an amino acid alkali metal halide complex crystal by slow evaporation method. The grown crystals were found to be transparent and have well defined morphology. The optical characteristics of the grown crystals were carried out with the help of UV-Vis Spectroscopy. The optical transmittances of the spectrums show that BAPC is more transparent than BACC. The Photoluminescence of the materials were determined by the Photoluminescent Spectroscopy

  7. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Messrs. Leroy F. Matthews (left) and Frank J. Novak (Lockheed Engineering & Sciences Co.) are preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully- engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instrument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  8. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Mr. Leroy F. Matthews (Lockheed Engineering & Sciences Co.) is connecting the Thermal Control Unit cables in preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully-engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  9. Optical study of Sb-S-I glass photonic crystals

    NASA Astrophysics Data System (ADS)

    Starczewska, Anna; Kępińska, Mirosława; Nowak, Marian; Szperlich, Piotr

    2015-12-01

    This work is focused on optical investigations of Sb-S-I glass photonic crystals based on three-dimensional opal template with a closed-packed face centered cubic (fcc) lattice prepared from monodisperse silicon (SiO2) spheres by gravity sedimentation. Three types of photonic structures have been examined: SiO2-opals, opals filled with Sb-S-I glass (direct opals) and Sb-S-I inverted opals obtained after removing SiO2 templates. Optical properties have been investigated by reflectance spectroscopy for wavelengths from 250 nm to 1100 nm. These measurements exhibit Bragg's peaks connected with photonic band gap that is tunable in position and width by varying the diameter of spheres and medium filling the opal. Values of the real parts of refractive index of the Sb-S-I in the fabricated inverted opals nmed[λ ∈ (850-950) nm] = 2.42 ± 0.08 and nmed[λ ∈ (675-750) nm] = 2.39 ± 0.11 have been determined.

  10. Radiation stability of visible and near-infrared optical and magneto-optical properties of terbium gallium garnet crystals.

    PubMed

    Geist, Brian; Ronningen, Reginald; Stolz, Andreas; Bollen, Georg; Kochergin, Vladimir

    2015-04-01

    Perspectives of terbium gallium garnet, Tb₃Ga₅O₁₂ (TGG), for the use of radiation-resistant high magnetic field sensing are studied. Long-term radiation stability of the TGG crystals was analyzed by comparing the optical and magneto-optical properties of a radiation-exposed TGG crystal (equivalent neutron dose 6.3×10¹³ n/cm²) to the properties of TGG control samples. Simulations were also performed to predict radiation damage mechanisms in the TGG crystal. Radiation-induced increase in the absorbance at shorter wavelengths was observed as well as a reduction in the Faraday effect while no degradation of magneto-optical effect was observed when at wavelengths above 600 nm. This suggests that TGG crystal would be a good candidate for use in magneto-optical radiation-resistant magnetic field sensors. PMID:25967201

  11. Radiation stability of visible and near-infrared optical and magneto-optical properties of terbium gallium garnet crystals.

    PubMed

    Geist, Brian; Ronningen, Reginald; Stolz, Andreas; Bollen, Georg; Kochergin, Vladimir

    2015-04-01

    Perspectives of terbium gallium garnet, Tb₃Ga₅O₁₂ (TGG), for the use of radiation-resistant high magnetic field sensing are studied. Long-term radiation stability of the TGG crystals was analyzed by comparing the optical and magneto-optical properties of a radiation-exposed TGG crystal (equivalent neutron dose 6.3×10¹³ n/cm²) to the properties of TGG control samples. Simulations were also performed to predict radiation damage mechanisms in the TGG crystal. Radiation-induced increase in the absorbance at shorter wavelengths was observed as well as a reduction in the Faraday effect while no degradation of magneto-optical effect was observed when at wavelengths above 600 nm. This suggests that TGG crystal would be a good candidate for use in magneto-optical radiation-resistant magnetic field sensors.

  12. Spectral, linear and nonlinear optical, electrical, mechanical behaviour of sodium succinate crystal

    NASA Astrophysics Data System (ADS)

    Venkatesan, G.; Pari, S.; Kathiravan, V.

    2016-09-01

    This article reports on the preparation and characterization of sodium succinate grown by the slow solvent evaporation method. The grown crystal was subjected to single crystal x-ray diffraction technique to determine the lattice parameters. Fourier transform infrared spectrum was recorded to identify the presence of functional groups. Linear optical studies were determined in the percentage of transmittance and other optical parameters like optical band gap, reflectance and refractive index. The nonlinear refractive index, absorption and optical limiting was measured through the z-scan technique using Nd:YAG laser. Fluorescence study was measured. The impedance spectrum used to determine the dc conductivity at first time. Dielectric constant, dielectric loss and ac conductivity of the crystal were measured. The mechanical properties were measured in the crystal. The predicted NLO properties, UV–vis absorption and Z-scan studies indicate that is an attractive material for nonlinear optics and photonics optical limiting applications.

  13. Spectral, linear and nonlinear optical, electrical, mechanical behaviour of sodium succinate crystal

    NASA Astrophysics Data System (ADS)

    Venkatesan, G.; Pari, S.; Kathiravan, V.

    2016-09-01

    This article reports on the preparation and characterization of sodium succinate grown by the slow solvent evaporation method. The grown crystal was subjected to single crystal x-ray diffraction technique to determine the lattice parameters. Fourier transform infrared spectrum was recorded to identify the presence of functional groups. Linear optical studies were determined in the percentage of transmittance and other optical parameters like optical band gap, reflectance and refractive index. The nonlinear refractive index, absorption and optical limiting was measured through the z-scan technique using Nd:YAG laser. Fluorescence study was measured. The impedance spectrum used to determine the dc conductivity at first time. Dielectric constant, dielectric loss and ac conductivity of the crystal were measured. The mechanical properties were measured in the crystal. The predicted NLO properties, UV-vis absorption and Z-scan studies indicate that is an attractive material for nonlinear optics and photonics optical limiting applications.

  14. Microstructure of spinel islands on the sapphire surface grown by ion implantation and annealing.

    PubMed

    Wang, Y; Liu, X P; Qin, G W

    2014-09-01

    Fe ions were implanted into α-Al2O3 single crystals (sapphire) at energy of 50 keV and annealed in an oxidizing environment. Transmission electron microscopy (TEM) investigation indicated that Fe ions in the near surface region precipitated as α-Fe2O3 islands and spinel islands on the specimen surface, at the same time, Fe ions in the region away from the surface precipitated as α-Fe particles in the interior region of specimen. Two orientation relationships (ORs) between the spinel islands and sapphire substrate were discovered as follows: (111)spinel∥(0001)sapphire, [1 1 2¯]spinel∥[1 1 2¯ 0]sapphire and (1 1 2¯)spinel∥(0 0 0 1)sapphire, [1 1 1]spinel∥[1 1 2¯ 0]sapphire. The first OR was frequently observed in the spinel/sapphire system, however, the second OR has never been reported before. The interfaces between the spinel islands and sapphire substrate are a type-3 incoherent interface (i.e. low-index OR in at least one direction with an ill-matched low-index habit planes). The formation of spinel islands on the specimen surface can be attributed to the oxidizing atmosphere and the low accelerating voltage for ion implantation.

  15. Growth, Structural And Optical Studies On Bis L-alanine Lithium Chloride (BLALC) Single Crystal

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Bis L-alanine Lithium Chloride (BLALC) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 15 x 9 x 4 mm3 have been obtained in 28 days. The grown crystals were colourless and transparent. Single crystal X-ray diffraction (XRD) study showed that BLALC belongs to orthorhombic system with a non-centro-symmetric space group P212121. The crystallinity of BLALC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. The functional groups of the grown crystals have been identified by FTIR studies. UV-visible transmittance spectrum was recorded to study the optical transparency of BLALC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique.

  16. Structural, optical, mechanical and dielectric studies of pure and doped L-Prolinium Trichloroacetate single crystals

    NASA Astrophysics Data System (ADS)

    Renuka, N.; Ramesh Babu, R.; Vijayan, N.; Vasanthakumar, Geetha; Krishna, Anuj; Ramamurthi, K.

    2015-02-01

    In the present work, pure and metal substituted L-Prolinium trichloroacetate (LPTCA) single crystals were grown by slow evaporation method. The grown crystals were subjected to single crystal X-ray diffraction (XRD), powder X-ray diffraction, FTIR, UV-Visible-NIR, hardness, photoluminescence and dielectric studies. The dopant concentration in the crystals was measured by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies of the pure and metal substituted LPTCA revealed that the grown crystals belong to the trigonal system. Ni2+ and Co2+ doping slightly altered the lattice parameters of LPTCA without affecting the basic structure of the crystal. FTIR spectral analysis confirms the presence of various functional groups in the grown crystals. The mechanical behavior of pure and doped crystals was analyzed by Vickers's microhardness test. The optical transmittance, dielectric and photoluminescence properties of the pure and doped crystals were analyzed.

  17. Structural, optical, mechanical and dielectric studies of pure and doped L-Prolinium trichloroacetate single crystals.

    PubMed

    Renuka, N; Ramesh Babu, R; Vijayan, N; Vasanthakumar, Geetha; Krishna, Anuj; Ramamurthi, K

    2015-02-25

    In the present work, pure and metal substituted L-Prolinium trichloroacetate (LPTCA) single crystals were grown by slow evaporation method. The grown crystals were subjected to single crystal X-ray diffraction (XRD), powder X-ray diffraction, FTIR, UV-Visible-NIR, hardness, photoluminescence and dielectric studies. The dopant concentration in the crystals was measured by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies of the pure and metal substituted LPTCA revealed that the grown crystals belong to the trigonal system. Ni(2+) and Co(2+) doping slightly altered the lattice parameters of LPTCA without affecting the basic structure of the crystal. FTIR spectral analysis confirms the presence of various functional groups in the grown crystals. The mechanical behavior of pure and doped crystals was analyzed by Vickers's microhardness test. The optical transmittance, dielectric and photoluminescence properties of the pure and doped crystals were analyzed.

  18. Sapphire hard X-ray Fabry-Perot resonators for synchrotron experiments.

    PubMed

    Tsai, Yi Wei; Wu, Yu Hsin; Chang, Ying Yi; Liu, Wen Chung; Liu, Hong Lin; Chu, Chia Hong; Chen, Pei Chi; Lin, Pao Te; Fu, Chien Chung; Chang, Shih Lin

    2016-05-01

    Hard X-ray Fabry-Perot resonators (FPRs) made from sapphire crystals were constructed and characterized. The FPRs consisted of two crystal plates, part of a monolithic crystal structure of Al2O3, acting as a pair of mirrors, for the backward reflection (0 0 0 30) of hard X-rays at 14.3147 keV. The dimensional accuracy during manufacturing and the defect density in the crystal in relation to the resonance efficiency of sapphire FPRs were analyzed from a theoretical standpoint based on X-ray cavity resonance and measurements using scanning electron microscopic and X-ray topographic techniques for crystal defects. Well defined resonance spectra of sapphire FPRs were successfully obtained, and were comparable with the theoretical predictions.

  19. Growth, Structural, Spectral and Optical Studies of Glycine Sodium Nitrate Doped Potassium Dihydrogen Phosphate Single Crystals

    NASA Astrophysics Data System (ADS)

    Loretta, Fernando; Rani, T. Josephine; Perumal, S.; Ramalingom, S.

    2011-10-01

    Single crystals of Pure and Glycine sodium nitrate (GSN) doped Potassium dihydrogen Phosphate (KDP) were grown from aqueous solution by slow evaporation technique. The cell parameters of the grown pure and GSN doped KDP crystals were estimated by Single X-ray diffraction studies. The functional groups present in the grown crystals were ascertained using FTIR spectral analysis. The UV-Vis-NIR transmission spectra reveals that the semiorganic dopant has increased the optical transparency of the KDP crystals.

  20. Quasi-transverse optical phonon mode in self-generated semipolar AlN grains embedded in c-oriented AlN matrix grown on sapphire using hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Hu, Y. Y.; Zhou, T. F.; Zheng, S. N.; Liu, X. H.; Zhao, J. J.; Su, X. J.; Huang, J.; Qiu, Y. X.; Zhang, J. C.; Xu, K.

    2016-05-01

    In this study, we present a microspectroscopic investigation on the quasi-transverse optical phonon modes Q(TO) in some self-generated aluminum nitride (AlN) grains grown on sapphire using hydride vapor phase epitaxy. Using X-ray diffraction and transmission electron microscope, these grains were confirmed to be embedded in (0001)-AlN (c-AlN) epitaxial matrix with an appearance plane of (10 1 ¯ 1 ) (s-plane). Two beam bright field images further showed that the AlN grains were free of dislocation. In-plane phonon anisotropy of the AlN grains was discussed in detail using angular-dependent polarized Raman spectroscopy. The dependence of pure Raman phonons intensity on rotation angle agrees well with the calculation. The Q(TO) phonon intensity exhibited similar behavior to that of A1(TO) phonon, which can be explained by Loudon's formula. However, the observed frequency fluctuation for the Q(TO) phonon differs from that of the pure phonon modes, which cannot be directly understood from the classic Loudon's formula. A modified Loudon's formula appropriate to non-normal incidence was presented to explain the observed Q(TO) phonon frequency fluctuation. Combining with the angular-dependent Raman spectra, we proposed that a small inclination of s-plane along with the various in-plane orientations in c-AlN matrix lead to the frequency fluctuation of Q(TO) in these embedded semipolar AlN grains.

  1. Fabrication of a new substrate for atomic force microscopic observation of DNA molecules from an ultrasmooth sapphire plate.

    PubMed Central

    Yoshida, K; Yoshimoto, M; Sasaki, K; Ohnishi, T; Ushiki, T; Hitomi, J; Yamamoto, S; Sigeno, M

    1998-01-01

    A new stable substrate applicable to the observation of DNA molecules by atomic force microscopy (AFM) was fabricated from a ultrasmooth sapphire (alpha-Al2O3 single crystal) plate. The atomically ultrasmooth sapphire as obtained by high-temperature annealing has hydrophobic surfaces and could not be used for the AFM observation of DNA. However, sapphire treated with Na3PO4 aqueous solution exhibited a hydrophilic character while maintaining a smooth surface structure. The surface of the wet-treated sapphire was found by x-ray photoelectron spectroscopy and AFM to be approximately 0.3 nm. The hydrophilic surface character of the ultrasmooth sapphire plate made it easy for DNA molecules to adhere to the plate. Circular molecules of the plasmid DNA could be imaged by AFM on the hydrophilic ultrasmooth sapphire plate. PMID:9545030

  2. High T(sub c) Superconducting Bolometer on Chemically Etched 7 Micrometer Thick Sapphire

    NASA Technical Reports Server (NTRS)

    Lakew, B.; Brasunas, J. C.; Pique, A.; Fettig, R.; Mott, B.; Babu, S.; Cushman, G. M.

    1997-01-01

    A transition-edge IR detector, using a YBa2Cu3O(7-x) (YBCO) thin film deposited on a chemically etched, 7 micrometer thick sapphire substrate has been built. To our knowledge it is the first such high T(sub c) superconducting (HTS) bolometer on chemically thinned sapphire. The peak optical detectivity obtained is l.2 x 10(exp 10) cmHz(sup 1/2)/W near 4Hz. Result shows that it is possible to obtain high detectivity with thin films on etched sapphire with no processing after the deposition of the YBCO film. We discuss the etching process and its potential for micro-machining sapphire and fabricating 2-dimensional detector arrays with suspended sapphire membranes. A 30 micrometer thick layer of gold black provided IR absorption. Comparison is made with the current state of the art on silicon substrates.

  3. Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

    NASA Astrophysics Data System (ADS)

    Sheelarani, V.; Shanthi, J.

    2015-06-01

    Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV-Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

  4. Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

    SciTech Connect

    Sheelarani, V.; Shanthi, J.

    2015-06-24

    Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV–Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

  5. Calculation of optical second-harmonic susceptibilities and optical activity for crystals

    SciTech Connect

    Levine, Z.H.

    1994-12-31

    A new generation of nearly first-principles calculations predicts both the linear and second-harmonic susceptibilities for a variety of insulating crystals, including GaAs, GaP, AlAs, AlP, Se, {alpha}-quartz, and c-urea. The results are typically in agreement with experimental measurements. The calculations have been extended to optical activity, with somewhat less success to date. The theory, based on a simple self-energy correction to the local density approximation, and results are reviewed herein.

  6. Simulation study on cascaded terahertz pulse generation in electro-optic crystals

    NASA Astrophysics Data System (ADS)

    Hattori, Toshiaki; Takeuchi, Kousuke

    2007-06-01

    We studied cascaded optical rectification processes for intense terahertz (THz) pulse generation in electro-optic crystals using simulations based on one-dimensional coupled propagation equations of THz and optical fields. We found that under ideal conditions of perfect phase matching and no absorption, cascaded optical rectification processes produce intense THz pulses with efficiencies exceeding the Manley-Rowe limit. Large red shifting of the pump light spectrum was observed. Effects of finite optical and THz absorption, phase mismatches, and pulse width were examined using parameters of a ZnTe crystal pumped by 800 nm pulses. THz field enhancement by multiple pulse pumping was also studied.

  7. Temperature Compensated Sapphire Resonator for Ultra-Stable Oscillator Capability at Temperatures Above 77 Kelvin

    NASA Technical Reports Server (NTRS)

    Dick, G.; Santiago, D.; Wang, R.

    1994-01-01

    We report on the design and test of a whispering gallery sapphire resonator for which the dominant (WGH xxxsubn11) microwave mode family shows frequency-stable, compensated operation for temperatures above 77 Kelvin. The resonator makes possible a new ultra-stable oscillator (USO) capability that promises performance improvements over the best available crystal quartz oscillators in a compact cryogenic package. A mechanical compensation mechanism, enabled by the difference between copper and sapphire expansion coefficients, tunes the resonator to cancel the temperature variation of sapphire's dielectric constant.

  8. Pumping of titanium sapphire laser

    NASA Astrophysics Data System (ADS)

    Jelínková, H.; Vaněk, P.; Valach, P.; Hamal, K.; Kubelka, J.; Škoda, V.; Jelínek, M.

    1993-02-01

    Two methods of Ti:Sapphire pumping for the generation of tunable laser radiation in the visible region were studied. For coherent pumping, the radiation of the second harmonic of a Nd:YAP laser was used and a maximum output energy of E out=4.5 mJ was reached from the Ti:Sapphire laser. For noncoherent pumping, two different lengths of flashlamp pulses were used and a maximum of E out=300 mJ was obtained. Preliminary estimations of the wavelength range of tunability were made.

  9. Plasmon electro-optic effect in a subwavelength metallic nanograting with a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Palto, S. P.; Barnik, M. I.; Kasyanova, I. V.; Geivandov, A. R.; Shtykov, N. M.; Artemov, V. V.; Gorkunov, M. V.

    2016-01-01

    The electro-optic effect in hybrid structures based on subwavelength metallic nanogratings in contact with a layer of a nematic liquid crystal has been experimentally studied. Metallic gratings are fabricated in the form of interdigitated electrodes, which makes it possible to use them not only as optical elements but also for the production of an electric field in a thin surface region of the layer of the liquid crystal. It has been shown that, owing to the electric-field-induced reorientation of molecules of the liquid crystal near the surface of the grating, it is possible to significantly control the spectral features of the transmission of light, which are caused by the excitation of surface plasmons. The electro-optic effect is superfast for liquid crystal devices because a change in the optical properties of the system requires the reorientation of molecules only in a very thin surface layer of the liquid crystal.

  10. Crystal growth rates and optical resolution of DL-methionine hydrochloride by preferential crystallization from aqueous solution

    NASA Astrophysics Data System (ADS)

    Srimahaprom, Watcharakarn; Flood, Adrian E.

    2013-01-01

    Optical resolution of DL-methionine hydrochloride (DL-met·HCl) by preferential crystallization was studied for the purification of L-met·HCl (the desired enantiomer) from supersaturated solutions of DL-met·HCl. The nucleation thresholds (NT) of DL-met·HCl affect the maximum resolution time suitable for preferential crystallization and also the percentage purity of the product crystals. Crystal growth rates of L-met·HCl single crystals both in supersaturated solutions of DL-met·HCl and in supersaturated solutions of pure L-met·HCl were measured in order to model the preferential crystallization more effectively. Results showed that the growth rate depends strongly on the relative supersaturation (especially from pure L-met·HCl solutions), that there is a wide crystal growth rate distribution in growth from both types of solution, and that the growth is faster from pure L-met·HCl solutions, as expected. A batch crystallizer seeded with L-met·HCl crystals was used to study the preferential crystallization, and to study the behavior of purity decrease of the product crystals during the crystallization process. The purity of the L-met·HCl product decreased to the equilibrium value over time, with almost no plateau at 100% purity (as is hoped for in preferential crystallizations). This is explainable by the very short induction times for nucleation in these solutions, and also that the L-met·HCl seed crystals may act as a template for the nucleation of the counter-enantiomer.

  11. Compact 4 cm aperture transmissive liquid crystal optical phased array for free-space optical communications

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Hua; Mahajan, Milind; Taber, Donald; Wen, Bing; Winker, Bruce

    2005-08-01

    There is a critical need for high bandwidth, high availability free-space optical communication links between the battlefield and the global information grid. Compact large aperture transceivers with low size, weight and power (SWaP) are needed to initiate and maintain communication links involving airborne platforms. The transceiver optical beam director typically contains fine and coarse steering stages. Existing beam director technology is based on electro-mechanical gimbaled mirrors with large SWaP that hinders deployment on many airborne platforms. To address the need for compact beam directors, we designed, fabricated, and tested an optical phased array (OPA) based on electro-optic dual frequency liquid crystal technology. This OPA has a transmissive architecture that enables a lower system SWaP, as compared to conventional reflective OPA. It has an 8 μm pixel pitch and steers over a 2.5° field of regard in one dimension at 1.55 μm. Two such OPAs can be stacked to steer in two dimensions. It has four independently addressable 1 cm x 4 cm regions arranged in a linear array to produce a continuous 4 cm x 4 cm aperture. The device incorporates novel addressing schemes to reduce the number of control channels by over an order of magnitude compared to conventional OPA addressing methods. It also utilizes proprietary low-loss transparent conductive TransconTM film for low optical absorption in the infrared. The OPA uses a custom multi-channel controller circuit operating at a 500 Hz frame rate. We present results on OPA design, fabrication, and optical performance on steering.

  12. Growth and birefringence studies of semi organic non-linear optical LHB single crystal

    NASA Astrophysics Data System (ADS)

    Jayaramakrishnan, V.; Prasanyaa, T.; Haris, M.; Bhoopathi, G.

    2015-02-01

    In the last few decades nonlinear optical materials are getting attention in the field of optical data storage, telecommunication, second harmonic generation (SHG) and optical signal processing, etc. In the present work we are reporting the single crystal growth of L-Histidine with hydro-bromic acid. The L-Histidine bromide (LHB) single crystals have been harvested from the solution in a span of 34 days by adopting slow cooling solution growth technique. The grown crystals have been subjected to powder X-ray diffraction studies to identify the cell parameters and structure. The crystalline perfection has been defined by rocking curve (HRXRD) analysis. Optical transmission spectra reveal the optical properties of the grown crystals. The Modified channel spectrum (MCS) method has been adopted for the study of spectral dependence of linear birefringence over the wavelength range 480-620 nm. The second harmonic generation efficiency was tested by using Kurtz and Perry method, keeping KDP as reference.

  13. Fabrication of optical element from unidirectional grown imidazole-imidazolium picrate monohydrate (IIP) organic crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Vivek, P.; Murugakoothan, P.

    2014-12-01

    Nonlinear optical bulk single crystal of Imidazole-imidazolium picrate monohydrate (IIP) has been grown by Sankaranarayanan-Ramasamy (SR) method using acetonitrile as solvent. First time we report the bulk growth of IIP crystal by SR method. The transparent IIP single crystal of maximum diameter 21 mm and length 46 mm was obtained by employing SR method. The grown crystal was subjected to high resolution X-ray diffraction, UV-vis-NIR transmittance, refractive index, hardness, dielectric and laser damage threshold studies. The crystalline perfection of the grown crystal was analyzed using HRXRD. Cut off wavelength and optical transmission window of the crystal was assessed by UV-vis-NIR and the refractive index of the crystal was found. The mechanical property of the crystal was estimated by Vicker's hardness test. The dielectric property of the crystal was measured as a function of frequency. The laser damage threshold value was determined. The particle size dependent second harmonic generation efficiency for IIP was evaluated with standard reference material potassium dihydrogen phosphate (KDP) by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching. The second harmonic generation (SHG) of IIP crystal was investigated by the SHG Maker fringes technique. The mechanism of growth is revealed by carrying out chemical etching using acetonitrile as etchant.

  14. Jones calculus modeling and analysis of the thermal distortion in a Ti:sapphire laser amplifier.

    PubMed

    Cho, Seryeyohan; Jeong, Jihoon; Yu, Tae Jun

    2016-06-27

    The mathematical modeling of an anisotropic Ti:sapphire crystal with a significant thermal load is performed. The model is expressed by the differential Jones matrix. A thermally induced distortion in the chirped-pulse amplification process is shown by the solution of the differential Jones matrix. Using this model, the thermally distorted spatio-temporal laser beam shape is calculated for a high-power and high-repetition-rate Ti:sapphire amplifier. PMID:27410590

  15. DPSSL pumped 20-TW Ti:sapphire laser system for DD fusion experiment

    NASA Astrophysics Data System (ADS)

    Sekine, T.; Hatano, Y.; Takeuchi, Y.; Kawashima, T.

    2016-03-01

    A diode-pumped solid-state laser (DPSSL) pumped 20-TW output Ti:sapphire laser system has been developed. A diode-pumped Nd:glass laser with output energy of 12.7 J in 527 nm was used as a pump source for a 20-TW Ti:sapphire amplifier. A CeLiB6O10 nonlinear optical crystal was used as a frequency doubler of the Nd:glass DPSSL[1]. Figure 1 shows typical output pulse energy of the 20-TW amplifier as a function of pumping energy and a near field pattern. A 1.65 J pulse energy was obtained by 4.5 J pump energy. The amplified seed pulse is compressed to typically 60 fs as shown in Fig. 1 by a vacuumed pulse compressor with 80% of transmissivity. Encircled energy ratio, into a circled with 8 μm diameter area, of far field pattern focused by off-axis parabolic mirror with F# of 3 is numerically evaluated to 40% at TW class output condition. Then focal intensity would reach to 1018W/cm2. This all- DPSSL system contributes for stable and continual investigation of laser induced plasma experiment. We have succeeded continual and high efficient generation of DD fusion neutron from CD nano-particles by cluster fusion scheme using the 20-TW laser. A yield of ∼105 neutrons per shot was stably observed during continuous 100 shots with repetition rate of 0.1Hz.

  16. Optical, thermal and surface microtopography studies of MoTe2 single crystals

    NASA Astrophysics Data System (ADS)

    Patel, D. D.; Desai, P. F.; Bhavsar, D. N.; Jani, A. R.

    2013-06-01

    Single crystals of MoTe2 grown by chemical vapour transport technique were used here. X-ray diffraction technique reveals that the MoTe2 crystals belong to hexagonal crystal structure. The optical response of these crystals has been obtained by UV-VIS-NIR spectroscopy. The transmittance of MoTe2 crystal has been used to calculate the refractive index (n), the extinction co-efficient (k) and both real(ɛr) and imaginary (ɛi) components of the dielectric constant as function of wavelength at room temperature. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were carried out for MoTe2 single crystals. The detailed surface microtopographic studies of these crystals by means of optical microscopy showed that the layer mechanism is predominant during growth. Even spiral growth is equally common on the as-grown faces.

  17. Boundary effects in finite size plasmonic crystals: focusing and routing of plasmonic beams for optical communications.

    PubMed

    Benetou, M I; Bouillard, J-S; Segovia, P; Dickson, W; Thomsen, B C; Bayvel, P; Zayats, A V

    2015-11-01

    Plasmonic crystals, which consist of periodic arrangements of surface features at a metal-dielectric interface, allow the manipulation of optical information in the form of surface plasmon polaritons. Here we investigate the excitation and propagation of plasmonic beams in and around finite size plasmonic crystals at telecom wavelengths, highlighting the effects of the crystal boundary shape and illumination conditions. Significant differences in broad plasmonic beam generation by crystals of different shapes are demonstrated, while for narrow beams, the propagation from a crystal onto the smooth metal film is less sensitive to the crystal boundary shape. We show that by controlling the boundary shape, the size and the excitation beam parameters, directional control of propagating plasmonic modes and their behaviour such as angular beam splitting, focusing power and beam width can be efficiently achieved. This provides a promising route for robust and alignment-independent integration of plasmonic crystals with optical communication components.

  18. Optical electric-field sensor based on angular optical bias using single β-BaB2O4 crystal.

    PubMed

    Li, Changsheng; Shen, Xiaoli; Zeng, Rong

    2013-11-01

    A novel optical electric-field sensor is proposed and demonstrated in experiment by use of a single beta barium borate (β-BaB2O4, BBO) crystal. The optical sensing unit is only composed of one BBO crystal and two polarizers. An optical phase bias of 0.5π is provided by using natural birefringence in the BBO crystal itself. A small angle (e.g., 0.6°) between the sensing light beam and principal axis of the crystal is required in order to produce the above optical bias. Thus the BBO crystal is used as the electric-field-sensing element and quarter waveplate. The ac electric field in the range of (1.4-703.2) kV/m has been measured with measurement sensitivity of 1.39 mV/(kV/m) and nonlinear error of 0.6%. Compared with lithium niobate crystal used as an electric-field sensor, main advantages of the BBO crystal include higher measurement sensitivity, compact configuration, and no ferroelectric ringing effect.

  19. Study of spectroscopic and thermal characteristics of nonlinear optical molecular crystals based on 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Pavlovetc, I. M.; Fokina, M. I.

    2016-08-01

    The paper presents the results of study of spectroscopic and thermal characteristics of molecular co-crystals: 2-aminopyridine-4-nitrophenol-4-mtrophenolate (2AP4N) and 2,6- diaminopyridine-4-nitrophenol-4nitrophenolate (26DAP4N). Crystals were successfully grown by slow evaporation technique. Optical transparency in the region of 190-1100 was found to be suitable for applications with cut off wavelengths 420 and 430 nm respectively. Thermogravimetric and differential thermal analysis show good quality and thermal stability for studied crystals. Kurtz and Perry powder technique proves that the crystals are acentric and have significant nonlinear optical response.

  20. Organic Single-Crystal Light-Emitting Transistor Coupling with Optical Feedback Resonators

    PubMed Central

    Bisri, Satria Zulkarnaen; Sawabe, Kosuke; Imakawa, Masaki; Maruyama, Kenichi; Yamao, Takeshi; Hotta, Shu; Iwasa, Yoshihiro; Takenobu, Taishi

    2012-01-01

    Organic light-emitting transistors (OLETs) are of great research interest because they combine the advantage of the active channel of a transistor that can control the luminescence of an in-situ light-emitting diode in the same device. Here we report a novel single-crystal OLET (SCLET) that is coupled with single crystal optical feedback resonators. The combination of single-crystal waveguides with native Fabry-Perot cavities, formed by parallel crystal edges, drastically lowers the threshold energy for spectral narrowing and non-linear intensity enhancement. We apply this structure to SCLETs and demonstrate the first fabrication of a SCLET with the optical feedback resonators. PMID:23248748

  1. Appearance of singularities of optical fields under torsion of crystals containing threefold symmetry axes.

    PubMed

    Skab, Ihor; Vasylkiv, Yurij; Zapeka, Bohdan; Savaryn, Viktoriya; Vlokh, Rostyslav

    2011-07-01

    We present an analysis of the effect of torsion stresses on the spatial distribution of optical birefringence in crystals of different point symmetry groups. The symmetry requirements needed so that the optical beam carries dislocations of the phase front are evaluated for the case when the crystals are twisted and the beam closely corresponds to a plane wave. It is shown that the torsion stresses can produce screw-edge, pure screw, or pure edge dislocations of the phase front in the crystals belonging to cubic and trigonal systems. The conditions for appearance of canonical and noncanonical vortices in the conditions of crystal torsion are analyzed.

  2. Review on recent progress of three-dimensional optical photonic crystal

    SciTech Connect

    Hsieh, Mei-Li; Kuang, Ping; Bur, James A.; Lin, Shawn-Yu; John, Sajeev

    2014-03-31

    Over the past two decades, the field of photonic-crystals has become one of the most influential realms of contemporary optics. In this paper, we will review two recent experimental progresses in three-dimensional photonic-crystal operating in optical wavelengths. The first is the observation of anomalous light-refraction, an acutely negative refraction, in a 3D photonic-crystal for light trapping, guiding and near-unity absorption. The second is the observation of quasi-coherent thermal emission from an all-metallic 3D photonic-crystal at elevated temperatures.

  3. Optical and dielectric properties of L-methionine L-methioninium hydrogen maleate single crystal

    NASA Astrophysics Data System (ADS)

    Vasudevan, P.; Sankar, S.; Gokulraj, S.

    2013-02-01

    An organic nonlinear optical single crystal L-methionine L-methioninium hydrogen maleate has been grown by solution growth technique. It is confirmed from XRD data that the crystal belongs to monoclinic system with non-centrosymmetric space group P21. Photoluminescence study was carried out for the grown crystal and maximum emission occurs at 395 nm. Dielectric measurements were made for the frequency range from 100 Hz to 5 MHz. The lower value of dielectric constant and dielectric loss at higher frequencies reveal that the material possesses enhanced optical quality with lesser defects. Nonlinear optical property was confirmed by Kurtz and Perry technique.

  4. Determination of the liquid crystals phase transition temperatures using optical rotation effect

    NASA Astrophysics Data System (ADS)

    Niu, Xiao-ling; Liu, Wei-guo; Liu, Peng; Cai, Chang-long

    2011-11-01

    Using optical rotation effect, a sensitive, simple optical analytical system is developed for determining the phase transition temperatures of liquid crystals (LCs). When a monochromatic polarized light passes through LCs sample and analyzer, the light intensity changes with temperature. Especially, during the phase transition process, the intensity varies greatly due to optical rotation effect. The variation of light intensity versus variation of temperature curve shows the phase transition temperatures of LCs clearly. The phase transition temperatures of three cholesteric liquid crystals (ChLCs) and a nematic liquid crystals (NLCs) were detected by this method, and compared with those of the differential scanning calorimetry (DSC) and polarized light microscope (PLM) methods.

  5. Liquid crystals as optical amplifiers for bacterial detection.

    PubMed

    Zafiu, C; Hussain, Z; Küpcü, S; Masutani, A; Kilickiran, P; Sinner, E-K

    2016-06-15

    Interactions of bacteria with target molecules (e.g. antibiotics) or other microorganisms are of growing interest. The first barrier for targeting gram-negative bacteria is layer of a Lipopolysaccharides (LPS). Liquid crystal (LC) based sensors covered with LPS monolayers, as presented in this study, offer a simple model to study and make use of this type of interface for detection and screening. This work describes in detail the production and application of such sensors based on three different LPS that have been investigated regarding their potential to serve as sensing layer to detect bacteria. The LPS O127:B8 in combination with a LC based sensor was identified to be most useful as biomimetic sensing surface. This LPS/LC combination interacts with three different bacteria species, one gram-positive and two gram-negative species, allowing the detection of bacterial presence regardless from their viability. It could be shown that even very low bacterial cell numbers (minimum 500 cell ml(-1)) could be detected within minutes (maximum 15 min). The readout mechanism is the adsorption of bacterial entities on surface bond LPS molecules with the LC serving as an optical amplifier.

  6. UV optical absorption spectra analysis of spodumene crystals from Brazil

    NASA Astrophysics Data System (ADS)

    Isotani, Sadao; Watari, Kazunori; Mizukami, Akiyoshi; Bonventi, Waldemar; Ito, Amando Siuiti

    2007-04-01

    The spectral decomposition analysis was applied to the optical absorption spectra of spodumene crystals from the Brazilian eastern pegmatitic province. The analyzed samples were natural, treated at 400 °C for 24 h and those irradiated with γ rays of 60Co with doses up to 5 MGy. The attributions of the lines were made taking in account highly accurate quantum mechanical calculations. The heated sample had only three lines, which were not affected by irradiation. One of them at 7.58 eV was attributed to an oxygen vacancy defect and the other two at 5.07 and 4.64 eV to a peroxy-type defect. The analysis of the growth of the lines with the irradiation showed that they belong to two groups of defects. The first group of lines at 4.2, 5.3 and 5.9 eV was attributed to a silanone-type defect. The other group of lines at 1.36, 2.0, 2.6, 3.6 and 5.0 eV was attributed to a type of Mn 3+ defect. The natural and irradiated samples also showed a line at 2.3 eV, which was attributed to another type of diamagnetic Mn 3+ defect.

  7. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-04-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4.

  8. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal.

    PubMed

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-01-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4. PMID:27126353

  9. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

    PubMed Central

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-01-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4. PMID:27126353

  10. Quasi-collinear tunable acousto-optic paratellurite crystal filters for wavelength division multiplexing and optical channel selection

    SciTech Connect

    Molchanov, V Ya; Makarov, O Yu; Voloshinov, V B

    2009-04-30

    Quasi-collinear acousto-optic interaction is studied in acoustically and optically anisotropic paratellurite crystals. The possible applications of this interaction in acousto-optic tunable filters with a high spectral resolution are discussed. Different modifications of devices are compared and variants of devices intended for processing light beams and selection of light signals in fibreoptic communication systems with wavelength division multiplexing (WDM) at {lambda} {approx_equal} 1550 nm are considered. (light modulation)

  11. Electronically controlled surface plasmon dispersion and optical transmission through metallic hole arrays using liquid crystal.

    PubMed

    Dickson, Wayne; Wurtz, Gregory A; Evans, Paul R; Pollard, Robert J; Zayats, Anatoly V

    2008-01-01

    The enhanced optical properties of metal films periodically perforated with an array of sub-wavelength size holes have recently been widely studied in the field of surface plasmon optics. The ability to design the optical transmission of such nanostructures, which act as plasmonic crystals, by varying their geometrical parameters gives them great flexibility for numerous applications in photonics, opto-electronics, and sensing. Transforming these passive optical elements into devices that may be actively controlled has presented a new challenge. Here, we report on the realization of an electrically controlled nanostructured optical system based on the unique properties of surface plasmon polaritonic crystals in contact with a liquid crystal (LC) layer. We discuss the effect of LC layer modulation on the surface plasmon dispersion, the related optical transmission and the underlying mechanism. The reported effect may be used to achieve active spectral tuneability and switching in a wide range of applications.

  12. Synthesis, crystal growth, solubility, structural, optical, dielectric and microhardness studies of Benzotriazole-4-hydroxybenzoic acid single crystals

    NASA Astrophysics Data System (ADS)

    Silambarasan, A.; Krishna Kumar, M.; Thirunavukkarasu, A.; Mohan Kumar, R.; Umarani, P. R.

    2015-06-01

    Organic Benzotriazole-4-hydroxybenzoic acid (BHBA), a novel second-order nonlinear optical single crystal was grown by solution growth method. The solubility and nucleation studies were performed for BHBA crystal at different temperatures 30, 35, 40 45 and 50 °C. Single crystal X-ray diffraction study reveals that the BHBA belongs to Pna21 space group of orthorhombic crystal system. The crystal perfection of BHBA was examined from powder and high resolution X-ray diffraction analysis. UV-visible and photoluminescence spectra were recorded to study its transmittance and excitation, emission behaviors respectively. Kurtz powder second harmonic generation test reveals that, the frequency conversion efficiency of BHBA is 3.7 times higher than that of potassium dihydrogen phosphate (KDP) crystal. The dielectric constant and dielectric loss values were estimated for BHBA crystal at various temperatures and frequencies. The mechanical property of BHBA crystal was studied on (110), (010) and (012) planes by using Vicker's microhardness test. The chemical etching study was performed on (012) facet of BHBA crystal to analyze its growth feature.

  13. Study of Third-Order Optical Nonlinearities of Se-Sn (Bi,Te) Quaternary Chalcogenide Thin Films Using Ti: Sapphire Laser in Femtosecond Regime

    NASA Astrophysics Data System (ADS)

    Yadav, Preeti; Sharma, Ambika

    2016-09-01

    The objective of the present research work is to study the nonlinear optical properties of quaternary Se-Sn (Bi,Te) chalcogenide thin films. A Z-scan technique utilizing 800 nm femtosecond laser source has been used for the determination of the nonlinear refractive index (n 2), two-photon absorption coefficient (β 2) and third-order susceptibility (χ (3)). In the measurement of n 2, an aperture is placed in the far field before the detector (closed aperture), while for the measurement of β 2, entire transmitted light is collected by the detector without an aperture (open aperture). Self-focusing has been observed in closed aperture transmission spectra. The appearance of the peak after the valley in this spectrum reflects the positive nonlinear refractive index. The calculated value of n 2 of the studied thin films varies from 1.06 × 10-12 cm2/W to 0.88 × 10-12 cm2/W. The compound-dependent behavior of n 2 is explained in this paper. We have also compared the experimental values of n 2 with the theoretically determined values, other compounds of chalcogenide glass and pure silica. The n 2 of the investigated thin films is found to be 3200 times higher than pure silica. The results of the open aperture Z-scan revealed that the value of β 2 of the studied compound is in the order of 10-8 cm/W. The behavior of two-photon absorption is described by means of the optical band gap (E g) of the studied compound. The variation in the figure-of-merit from 0.32 to 1.4 with varying Sn content is also reported in this paper. The higher value of nonlinearity makes this material advantageous for optical fibers, waveguides and optical limiting devices.

  14. Investigations on the electrical, thermal and optical properties of the nonlinear optical allylthiourea mercury chloride single crystals

    SciTech Connect

    Sreekanth, G.; Chandralingam, S.; Philip, Jacob; Jayalakshmy, M.S.; Philip, Reji; Sridharan, Kishore; Santhosh Kumar, R.; Joseph, Ginson P.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► The single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride are synthesized using slow evaporation technique. ► The bandgap of allylthiourea mercury chloride crystal is found to be about 3.18 eV. ► The optical nonlinearity of the crystal sample are studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and three photon absorption effect has been found. ► An improved photo pyroelectric is used to find the thermal parameters of the crystal. ► The piezoelectric charge coefficient is determined. -- Abstract: Single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride were synthesized from aqueous solution using slow evaporation technique at ambient temperature. The grown crystals are confirmed by elemental analysis. The band gap of Allylthiourea mercury chloride crystal was found to be about 3.18 eV. The optical nonlinearity of the crystal sample was studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and a three-photon absorption effect has been found. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the sample were carried out by Agillent E 4980 A LCR meter at different temperatures. An improved photopyroelectric technique was used to find the thermal parameters of the crystal. The piezo electric charge coefficient is also determined.

  15. Experimental demonstration of joule-level non-collinear optical parametric chirped-pulse amplification in yttrium calcium oxyborate.

    PubMed

    Yu, Lianghong; Liang, Xiaoyan; Li, Jinfeng; Wu, Anhua; Zheng, Yanqing; Lu, Xiaoming; Wang, Cheng; Leng, Yuxin; Xu, Jun; Li, Ruxin; Xu, Zhizhan

    2012-05-15

    In this Letter, we report on what is, to our knowledge, the first experimental demonstration of yttrium calcium oxyborate (YCOB) for joule-level and broadband non-collinear optical parametric chirped-pulse amplification centered at 800 nm. Based on a Ti:sapphire chirped-pulse amplification front end, an amplified signal energy of 3.36 J was generated with a pump of 35 J in the crystal. Compressed pulse duration of 44.3 fs, with a bandwidth of 49 nm, was achieved. The results confirm that YCOB crystal is another potential alternative as a final amplifier besides Ti:sapphire in a petawatt laser at 800 nm.

  16. Optical parametric chirped pulse amplification and spectral shaping of a continuum generated in a photonic band gap fiber.

    PubMed

    Hugonnot, E; Somekh, M; Villate, D; Salin, F; Freysz, E

    2004-05-31

    A chirped pulse, spectrally broadened in a photonic bandgap optical fiber by 120 fs Ti:Sapphire laser pulses, is parametrically amplified in a BBO crystal pumped by a frequency doubled nanosecond Nd:YAG laser pulse. Without changing the frequency of the Ti:Sapphire, a spectral tunability of the amplified pulses is demonstrated. The possibility to achieve broader spectral range amplification is confirmed for a non-collinear pump-signal interaction geometry. For optimal non-collinear interaction geometry, the pulse duration of the original and amplified pulse are similar. Finally, we demonstrate that the combination of two BBO crystals makes it possible to spectrally shape the amplified pulses.

  17. Bulk crystal growth, optical, mechanical and ferroelectric properties of new semiorganic nonlinear optical and piezoelectric Lithium nitrate monohydrate oxalate single crystal

    NASA Astrophysics Data System (ADS)

    Dalal, Jyoti; Kumar, Binay

    2016-01-01

    New semiorganic nonlinear optical single crystals of Lithium nitrate oxalate monohydrate (LNO) were grown by slow evaporation solution technique. Single crystal X-ray diffraction study indicated that LNO crystal belongs to the triclinic system with space group P1. Various functional groups present in the material were identified by FTIR and Raman analysis. UV-vis study showed the high transparency of crystals with a wide band gap 5.01 eV. Various Optical constants i.e. Urbach energy (Eu), extinction coefficient (K), refractive index, optical conductivity, electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. A sharp emission peak was found at 438 nm in photoluminescence measurement, which revealed suitability of crystal for fabricating violet lasers. In dielectric studies, a peak has been observed at 33 °C which is due to ferroelectric to paraelectric phase transition. Piezoelectric charge coefficients (d33 = 9.2 pC/N and g33) have been calculated, which make it a suitable for piezoelectric devices applications. In ferroelectric studies, a saturated loop was found in which the values of coercive field and remnant polarization were found to be 2.18 kV/cm and 0.39 μC/cm2, respectively. Thermal behavior was studied by TGA and DSC studies. The relative SHG efficiency of LNO was found to be 1.2 times that of KDP crystal. In microhardness study, Meyer's index value was found to be 1.78 which revealed its soft nature. These optical, dielectric, piezoelectric, ferroelectric, mechanical and non-linear optical properties of grown crystal establish the usefulness of this material for optoelectronics, non-volatile memory and piezoelectric devices applications.

  18. Synthesis, growth, structural, optical, thermal and mechanical properties of an organic Urea maleic acid single crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Vinothkumar, P.; Kumar, R. Mohan; Jayavel, R.; Bhaskaran, A.

    2016-07-01

    A potential organic urea maleic acid (UMA) was synthesized and single crystals were grown at room temperature by slow evaporation and seed rotation methods. The grown crystal has been subjected to single crystal XRD analysis and found to have been crystallized in a noncentrosymmetric monoclinic crystal system with Cc as space group. The High resolution X-ray diffraction analysis revealed that the specimen is free from structural grain boundaries. The transparency of the grown crystal was confirmed by optical absorption and transmittance spectra with lower cut-off wavelength of 285 nm. The microhardness test was carried out on different planes to study the load dependent hardness values. The dislocation density of the UMA crystal was estimated from the etching studies. The dielectric permittivity and dielectric loss of the grown crystal was carried out as a function of frequency for different temperatures along three crystallographic axes. Thermal properties of UMA crystals were studied by TG-DTA analysis and it is stable upto 112 °C. The laser induced surface damage threshold of the grown crystal was measured using Nd: YAG laser. The birefringence of the crystal measured in the visible region was found to vary with the wavelength. The particle size dependent SHG of the sample was measured with different input energies by Kurtz's powder method using Nd:YAG laser.

  19. An investigation of the optical properties of cholesterol crystals in human synovial fluid

    NASA Astrophysics Data System (ADS)

    Zakharova, M. M.; Nasonova, V. A.; Konstantinova, A. F.; Chudakov, V. S.; Gaĭnutdinov, R. V.

    2009-05-01

    The synovial fluid of patients with rheumatoid diseases has been investigated. The presence of cholesterol crystals in the synovial fluid is revealed by polarization microscopy. A comparative analysis of the composition and properties of synovial fluid and the optical properties of cholesterol crystals is performed. It is established that the size, number, and growth of cholesterol crystals are interrelated to the synovial fluid composition. It is shown that rheumatoid diseases can be accompanied by the formation of cholesterol crystals in the synovial fluid from different joints and in rheumatic nodules. It is shown that all investigated crystals have a significant birefringence.

  20. Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals

    NASA Astrophysics Data System (ADS)

    Swarna Sowmya, N.; Sampathkrishnan, S.; Vidyalakshmi, Y.; Sudhahar, S.; Mohan Kumar, R.

    2015-06-01

    Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1064 nm.

  1. Growth and characterization of L-alanine cadmium bromide a semiorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Ilayabarathi, P.; Chandrasekaran, J.

    2012-10-01

    A new semiorganic nonlinear optical crystal, L-alanine cadmium bromide (LACB) was grown from aqueous solution by slow solvent evaporation method at room temperature. As grown crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LACB crystallizes in orthorhombic system and unit cell parameters a = 5.771(2) Å, b = 6.014(4) Å, c = 12.298(2) Å, α = β = γ = 90° and volume = 426.8(3) Å3. The mode of vibrations of different molecular groups present in the crystal was identified by FTIR study. The grown crystals were found to be transparent in the entire visible region. The thermal strength and the decomposition of the grown crystals were studied using TG/DTA and DSC analysis. Dielectric measurement revealed that the crystals had very low dielectric constant at higher frequency in room temperature. The mechanical behavior was studied by Vicker's microhardness tester. The grown crystal has negative photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.356 eV. The NLO property of crystal using modified Kurtz-Perry powder technique with Nd:YAG laser light of wavelength 1064 nm indicated that their second harmonic generation (SHG) efficiency was half that of pure KDP.

  2. Optical properties of planar nematic liquid crystals samples which are parallel oriented by nanofibers

    NASA Astrophysics Data System (ADS)

    Yusuf, Yusril; Kusumasari, Ervanggis Minggar; Ula, Nur Mufidatul; Jahidah, Khannah; Triyana, Kuwat; Sosiati, Harini; Harsojo

    2016-04-01

    Optical properties of two nematic liquid crystals, i.e., 4-methoxybenzylidene-4-butylaniline (MBBA) and 4-cyano-4'-pentylbiphenyl (5 CB) which are parallel oriented by nanofibers has been successfully performed. Planar samples of liquid crystals were made using polyvinyl alcohol (PVA) nanofiber from electrospinning process. Electrospinning method was modified using copper (Cu) as gap collector. These planar samples area are 15 mm x 25 mm. Optical characteristic of these samples were studied by using optical polarizing microscope. The optical intensity changes by a rotationof crossed polarizers is observed. The sinusoidal intensity change was observedin these samples as such as in the planar sample prepared by the rubbing method.

  3. Determination of piezo-optic coefficients of crystals by means of four-point bending.

    PubMed

    Krupych, Oleg; Savaryn, Viktoriya; Krupych, Andriy; Klymiv, Ivan; Vlokh, Rostyslav

    2013-06-10

    A technique developed recently for determining piezo-optic coefficients (POCs) of isotropic optical media, which represents a combination of digital imaging laser interferometry and a classical four-point bending method, is generalized and applied to a single-crystalline anisotropic material. The peculiarities of measuring procedures and data processing for the case of optically uniaxial crystals are described in detail. The capabilities of the technique are tested on the example of canonical nonlinear optical crystal LiNbO3. The high precision achieved in determination of the POCs for isotropic and anisotropic materials testifies that the technique should be both versatile and reliable.

  4. Crossover regime of optical vortices generation via electro-optic nonlinearity: the problem of optical vortices with the fractional charge generated by crystals.

    PubMed

    Vasylkiv, Yurij; Skab, Ihor; Vlokh, Rostyslav

    2014-09-01

    In this work, we analyze the behavior of topological defects of optical indicatrix orientation induced by a conically shaped electric field in crystals in a crossover regime that appears at intermediate fields separating the regimes of prevailing Pockels and Kerr electro-optic nonlinearities. We have found that increases in the electric voltage applied to a crystal induce neither topological defects, with the strengths being not multiples of ½, or the optical vortices with fractional charges. Instead, there appear some additional topological defects of the optical indicatrix orientation, the behavior of which we have studied in detail.

  5. Optical tuning of three-dimensional photonic crystals fabricated by femtosecond direct writing

    NASA Astrophysics Data System (ADS)

    McPhail, Dennis; Straub, Martin; Gu, Min

    2005-08-01

    In this letter, we report on an optically tunable three-dimensional photonic crystal that exhibits main gaps in the 3-4μm range. The photonic crystal is manufactured via a femtosecond direct writing technique. Optical tuning is achieved by a luminary polling technique with a low-power polarized laser beam. The refractive index variation resulting from liquid-crystal rotation causes a shift in the photonic band gap of up to 65 nm with an extinction of transmission of up to 70% in the stacking direction. Unlike other liquid-crystal tuning techniques where a pregenerated structure is infiltrated, this optical tuning method is a one-step process that allows arbitrary structures to be written into a solid liquid-crystal-polymer composite and leads to a high dielectric contrast.

  6. Spectral, optical and mechanical studies on L-histidine hydrochloride monohydrate (LHC) single crystals grown by unidirectional growth technique

    NASA Astrophysics Data System (ADS)

    Robert, R.; Justin Raj, C.; Krishnan, S.; Uthrakumar, R.; Dinakaran, S.; Jerome Das, S.

    2010-08-01

    Single crystals of nonlinear optical L-histidine hydrochloride monohydrate (LHC) were grown in an aqueous solution by the unidirectional crystal growth method within a period of 45 days along (1 0 1) plane. The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm their orthorhombic structure having space group P2 12 12 1. Values of several physical parameters were determined for the grown crystal. Optical transmission studies revealed very low absorption and band gap energy was calculated for the LHC crystals. Further, some optical constant were also determined for the grown crystals. Anisotropy in Vicker's microhardness led to the assessment of fracture toughness, brittleness index and yield strength for the synthesized crystals. Nonlinear optical studies were carried out for the grown crystal and second harmonic generation (SHG) efficiency was found to be three times that of KDP crystals.

  7. Growth and characterization of a novel nonlinear optical borate crystal--yttrium calcium borate (YCB).

    PubMed

    Arun Kumar, R; Arivanandhan, M; Dhanasekaran, R; Hayakawa, Y

    2013-06-01

    A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm(2).

  8. REVIEWS OF TOPICAL PROBLEMS: Optical bistability, multistability, and instabilities in liquid crystals

    NASA Astrophysics Data System (ADS)

    Arakelyan, S. M.

    1987-12-01

    The physical aspects of the manifestation of optical bistability, instabilities, and stochasticity in strongly nonlinear media in the form of liquid crystals subjected to laser radiation fields are discussed. The stress is on experimental research. Optical bistability and multistability are considered for a number of light-induced effects in homogeneous and inhomogeneous liquid crystals. The special features of these effects in liquids crystals, associated with the field-induced structural phase transitions, are stressed and the concept of intrinsic (mirrorless) optical bistability is introduced. General nonlinear systems with optical bistability are considered. An analysis is made of instabilities and stochasticity manifested in experiments on light-induced reorientation of liquid crystals in the presence of fields of different origin, giving rise to oscillatory and chaotic processes in the case of self-modulation of the transmitted light.

  9. Growth and characterization of a new organic nonlinear optical crystal: semicarbazone of p-dimethylamino benzaldehyde

    NASA Astrophysics Data System (ADS)

    Manivannan, S.; Dhanuskodi, S.

    2003-10-01

    Semicarbazone of p-dimethylamino benzaldehyde (SCPDB) is a new organic material with interesting quadratic nonlinear optical properties, in particular second harmonic generation (SHG). SCPDB was synthesized and single crystals were grown by low temperature solution method. Unit cell parameters were evaluated by single crystal X-ray diffraction technique. The formation of the material was confirmed qualitatively by FT-IR and FT-Raman spectral analyses and its optical transmittance studied. SHG efficiency is found to be comparable to urea.

  10. Mechano-optical wavelength tuning in a photonic crystal microcavity with sub-1 V drive voltage.

    PubMed

    Abdulla, Shahina M C; Kauppinen, Lasse J; Krijnen, Gijs J M; de Ridder, René M

    2012-06-01

    A micro-bimorph cantilever with self-aligned nanotips is monolithically integrated with a photonic crystal based device using optical and deep UV lithography techniques. Upon electrostatic actuation, the dielectric nanotips perturb the optical field, providing electromechano-optical modulation of light. Static tuning of the optical transmission spectra by more than 600 pm is measured with a sub-1 V drive voltage, resulting in a modulation as high as 21 dB. The observed strong electromechano-optical effect may find application in power efficient devices for optical communication networks, such as wavelength routing elements.

  11. Synthesis, structure, crystal growth and characterization of a novel semiorganic nonlinear optical L-proline lithium bromide monohydrate single crystal

    NASA Astrophysics Data System (ADS)

    Sathiskumar, S.; Balakrishnan, T.; Ramamurthi, K.; Thamotharan, S.

    2015-03-01

    L-Proline lithium bromide monohydrate (LPLBM), a promising semiorganic nonlinear optical material, was synthesized and single crystals of LPLBM were grown from solution by slow evaporation technique. Single crystal X-ray structure solution reveals that the grown crystal belongs to monoclinic system with space group P21. Presence of various functional groups was identified by FT-IR and FT-Raman spectral analyses. UV-Vis-NIR spectroscopic study shows that the LPLBM crystal possesses 90% of transmittance in the range of 250-1100 nm. Vickers microhardness values, the dielectric constant and dielectric loss of the LPLBM crystal were reported. Elemental analysis by energy dispersive X-ray analysis shows the presence of carbon, nitrogen, oxygen and bromine. The surface morphology of the crystal was investigated using scanning electron microscopic study. The thermal stability of the LPLBM crystal was studied from TGA and DSC analysis. Second harmonic generation efficiency of the LPLBM crystal measured by Kurtz and Perry powder technique using Nd:YAG laser is about 0.3 times that of urea.

  12. Partially coherent wavefront propagation simulations for inelastic x-ray scattering beamline including crystal optics

    NASA Astrophysics Data System (ADS)

    Suvorov, Alexey; Cai, Yong Q.; Sutter, John P.; Chubar, Oleg

    2014-09-01

    Up to now simulation of perfect crystal optics in the "Synchrotron Radiation Workshop" (SRW) wave-optics computer code was not available, thus hindering the accurate modelling of synchrotron radiation beamlines containing optical components with multiple-crystal arrangements, such as double-crystal monochromators and high-energy-resolution monochromators. A new module has been developed for SRW for calculating dynamical diffraction from a perfect crystal in the Bragg case. We demonstrate its successful application to the modelling of partially-coherent undulator radiation propagating through the Inelastic X-ray Scattering (IXS) beamline of the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. The IXS beamline contains a double-crystal and a multiple-crystal highenergy- resolution monochromator, as well as complex optics such as compound refractive lenses and Kirkpatrick-Baez mirrors for the X-ray beam transport and shaping, which makes it an excellent case for benchmarking the new functionalities of the updated SRW codes. As a photon-hungry experimental technique, this case study for the IXS beamline is particularly valuable as it provides an accurate evaluation of the photon flux at the sample position, using the most advanced simulation methods and taking into account parameters of the electron beam, details of undulator source, and the crystal optics.

  13. Influence of Acoustic Field Structure on Polarization Characteristics of Acousto-optic Interaction in Crystals

    NASA Astrophysics Data System (ADS)

    Muromets, A. V.; Trushin, A. S.

    Influence of acoustic field structure on polarization characteristics of acousto-optic interaction is investigated. It is shown that inhomogeneity of acoustic field and mechanism of ultrasound excitation causes changes in values of acousto-optic figure of merit for ordinary and extraordinary light beams in comparison with theoretic values. The theoretic values were derived under assumption that acoustic wave is homogeneous. Experimental analysis was carried out in acousto-optic cell based on lithium niobate crystal where the acoustic wave propagates at the angle 13 degrees to Z axis of the crystal. We used three different methods of ultrasound generation in the crystal: by means of external piezotransducer, by interdigital transducer and by two sets of electrodes placed on top of the crystal surface. In the latter case, the first pair of the electrodes was directed along X crystal axis, while the second pair of the electrodes was directed orthogonally to X crystal axis and the direction of ultrasound. Obtained values for diffraction efficiencies for ordinary and extraordinary polarized optical beams were qualitatively different which may be caused by spatial inhomogeneity of the generated acoustic waves in the crystal. Structure of acoustic field generated by these sets of electrodes was examined by laser probing. We performed the analysis of the acoustic field intensity using acousto-optic method. A relation of diffraction efficiencies for ordinary and extraordinary light waves was measured during each iteration of the laser probing.

  14. Ultra-fast solid state electro-optical modulator based on liquid crystal polymer and liquid crystal composites

    SciTech Connect

    Ouskova, Elena; Sio, Luciano De Vergara, Rafael; Tabiryan, Nelson; White, Timothy J.; Bunning, Timothy J.

    2014-12-08

    A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.

  15. Highly efficient acousto-optic diffraction in Sn2P2S6 crystals.

    PubMed

    Martynyuk-Lototska, I Yu; Mys, O G; Grabar, A A; Stoika, I M; Vysochanskii, Yu M; Vlokh, R O

    2008-01-01

    We have studied the acousto-optic (AO) diffraction in Sn2P2S6 crystals and found that they manifest high values of an AO figure of merit. The above crystals may therefore be used as highly efficient materials in different AO applications.

  16. Optical properties of bismuth-doped KCl and SrF2 crystals

    NASA Astrophysics Data System (ADS)

    Firstov, S. V.; Zhao, M.; Su, L.; Yang, Q.; Iskhakova, L. D.; Firstova, E. G.; Alyshev, S. V.; Riumkin, K. E.; Dianov, E. M.

    2016-09-01

    Structural and spectroscopic properties of the pristine and γ-irradiated Bi-doped KCl and SrF2 crystals grown by the Bridgman technique were studied. New emission bands in the visible and near IR regions from the irradiated crystals were observed. An origin of optical centers responsible for near IR luminescence is discussed.

  17. Effect of temperature gradient on the optical quality of mercurous chloride crystals

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Davies, D. K.; Gottlieb, M.; Henningsen, T.; Mazelsky, R.

    1989-01-01

    Single crystals of mercurous chloride were grown at temperature gradients of 8, 11 and 17 K/cm by the physical vapor transport method. The optical quality of these crystals was evaluated by measuring bulk scattering and inhomogeneity of refractive index by birefringence interferometry. It was observed that a high temperature gradient at the solid-vapor interface induced thermal stresses and crystals showed higher scattering and irregular fringes.

  18. Oxidation states of Fe and Ti in blue sapphire

    NASA Astrophysics Data System (ADS)

    Wongrawang, P.; Monarumit, N.; Thammajak, N.; Wathanakul, P.; Wongkokua, W.

    2016-02-01

    X-ray absorption near-edge spectroscopy (XANES) can be used to study the oxidation state of a dilute system such as transition metal defects in solid-state samples. In blue sapphire, Fe and Ti are defects that cause the blue color. Inter-valence charge transfer (IVCT) between Fe2+ and Ti4+ has been proposed to describe the optical color’s origin. However, the existence of divalent iron cations has not been thoroughly investigated. Fluorescent XANES is therefore employed to study K-edge absorptions of Fe and Ti cations in various blue sapphire samples including natural, synthetic, diffused and heat-treated sapphires. All the samples showed an Fe absorption edge at 7124 eV, corresponding to the Fe3+ state; and Ti at 4984 eV, corresponding to Ti4+. From these results, we propose Fe3+-Ti4+ mixed acceptor states located at 1.75 eV and 2.14 eV above the valence band of corundum, that correspond to 710 nm and 580 nm bands of UV-vis absorption spectra, to describe the cause of the color of blue sapphire.

  19. Growth, Optical, Dielectric and Ferroelectric Properties of Non-Linear Optical Single Crystal: Glycine-Phthalic Acid

    NASA Astrophysics Data System (ADS)

    Suresh, Sagadevan

    2016-07-01

    Single crystals of glycine-phthalic acid (GPA) were grown by slow evaporation process using aqueous solution. X-ray diffraction analysis was used to examine its cell structure and it was found that the GPA crystal corresponded to the orthorhombic system. To identify absorption range and cut-off wavelength for the GPA crystal, UV-visible spectrum was recorded. UV-visible spectroscopy was used to study the optical constants such as the refractive index, the extinction coefficient, electrical susceptibility, and optical conductivity. As a function of different frequencies and temperatures, the dielectric constant and the dielectric loss were examined. The electrical properties like plasma energy, Penn gap, Fermi energy, and polarizability were determined for the analysis of the second harmonic generation (SHG). Using the Kurtz powder technique, the SHG of the GPA crystal was studied. Investigations relating to hysteresis were carried out to ascertain the ferroelectric nature of the material.

  20. Growth, Optical, Dielectric and Ferroelectric Properties of Non-Linear Optical Single Crystal: Glycine-Phthalic Acid

    NASA Astrophysics Data System (ADS)

    Suresh, Sagadevan

    2016-11-01

    Single crystals of glycine-phthalic acid (GPA) were grown by slow evaporation process using aqueous solution. X-ray diffraction analysis was used to examine its cell structure and it was found that the GPA crystal corresponded to the orthorhombic system. To identify absorption range and cut-off wavelength for the GPA crystal, UV-visible spectrum was recorded. UV-visible spectroscopy was used to study the optical constants such as the refractive index, the extinction coefficient, electrical susceptibility, and optical conductivity. As a function of different frequencies and temperatures, the dielectric constant and the dielectric loss were examined. The electrical properties like plasma energy, Penn gap, Fermi energy, and polarizability were determined for the analysis of the second harmonic generation (SHG). Using the Kurtz powder technique, the SHG of the GPA crystal was studied. Investigations relating to hysteresis were carried out to ascertain the ferroelectric nature of the material.

  1. Optically isotropic liquid crystal media formulated by doping star-shaped cyclic oligosiloxane liquid crystal surfactants in twin nematic liquid crystals.

    PubMed

    Kim, Namil; Kim, Dae-Yoon; Park, Minwook; Choi, Yu-Jin; Kim, Soeun; Lee, Seung Hee; Jeong, Kwang-Un

    2015-05-21

    The formation of optically isotropic liquid crystal (LC) media has been investigated by doping the star-shaped LC molecular surfactants (SiLC) into the rod-shaped twin LC host molecules (DiLC). The experimental phase diagram was constructed on the basis of differential scanning calorimetry (DSC) and then a theoretical calculation was conducted through a combined Flory-Huggins (FH)/Maier-Saupe-McMillan (MSM)/phase field (PF) model to account for the experimental results. The phase diagram of the SiLC/DiLC mixtures revealed the broad coexistence regions such as smectic A + crystal (SmA1 + Cr2), liquid + crystal (L1 + Cr2), and liquid + nematic (L1 + N2) at the intermediate composition along with the narrow single phase crystal (Cr2), smectic (SmA1), and nematic (N2) regions. The morphologies and structures of these coexistence regions were further confirmed by polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). At the 80/20 SiLC/DiLC composition, the optical anisotropy was induced under an alternating current (AC) electric field above its isotropization temperature. The formation of an optically isotropic LC medium in mixtures of the SiLC molecular surfactants and nematic LC host may allow us to develop new electro-optical devices.

  2. Optical properties of KDP crystals doped with pyrenetetrasulfonic acid salt

    NASA Astrophysics Data System (ADS)

    Pritula, I. M.; Bezkrovnaya, O. N.; Lopin, A. V.; Kolybaeva, M. I.; Puzikov, V. M.; Zubatyuk, R. I.; Shishkin, O. V.; Gayvoronsky, V. Ya.

    2013-03-01

    KDP crystals with incorporated molecules of the luminophore 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (SPA) were grown from KH2PO4 solutions by the temperature lowering method. The luminescence spectra of KDP/SPA crystals and SPA solutions in distilled water and in KH2PO4 solutions, were studied. The increase of the dye content gives rise to excimer luminescence in the solutions and in KDP crystals, which is due to the formation of associated dye molecules. SPA molecules possessing negative electrostatic potential are incorporated into the pyramidal growth sector of KDP crystal.

  3. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, Charles E.; Eimerl, David; Velsko, Stephan P.; Roberts, David

    1993-01-01

    Temperature-insensitive, phase-matched harmomic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions.

  4. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, C.E.; Eimerl, D.; Velsko, S.P.; Roberts, D.

    1993-11-23

    Temperature-insensitive, phase-matched harmonic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions. 12 figures.

  5. Precise prediction of optical responses of liquid-crystal display products using a behavioral model of liquid crystal

    NASA Astrophysics Data System (ADS)

    Park, Chansoo; Cho, Youngmin; Kim, Jong-Man; Kim, Jongbin; Lee, Seung-Woo

    2012-01-01

    We propose a precise circuit model to estimate transient optical responses of an active-matrix liquid crystal display (AMLCD). Liquid crystal (LC) molecules in the pixel is behaviorally modeled by using the first-order system that is described by Verilog-A. Capacitance-voltage (C-V) characteristics of a pixel determine the accuracy of the dynamic responses. Measuring C-V characteristics is impossible because pixels are driven by switching transistors in the AMLCD. We propose a method to obtain the C-V data from natural optical responses. Estimated optical responses based on the C-V data extracted by our proposal show more accurate results than those based on C-V data obtained by using transmittance-voltage data. It is demonstrated that our behavioral model enables us to predict very accurate transient responses, which makes it possible to design LCD products with lower costs.

  6. Comparison of the optical parameters of a CaF{sub 2} single crystal and optical ceramics

    SciTech Connect

    Palashov, O V; Khazanov, E A; Mukhin, I B; Mironov, I A; Smirnov, A N; Dukel'skii, K V; Fedorov, Pavel P; Osiko, Vyacheslav V; Basiev, Tasoltan T

    2007-01-31

    Single crystal and optical ceramic CaF{sub 2} samples are studied by the method of thermally induced depolarisation of laser radiation at 1076 nm. The absorption coefficients of the single crystal and ceramics are estimated as {alpha} < 4.5x10{sup -4} cm{sup -1} and {alpha} < 1.33x10{sup -3} cm{sup -1}, respectively. (letters)

  7. Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

    NASA Technical Reports Server (NTRS)

    Choi, Sang; King, Glen; Park, Yeonjoon

    2009-01-01

    SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than

  8. Crystalline perfection, optical and third harmonic generation analyses of non-linear optical single crystal of L-lysine acetate.

    PubMed

    Rani, Neelam; Vijayan, N; Thukral, Kanika; Maurya, K K; Haranath, D; Bhagavannarayana, G; Verma, S; Wahab, M A

    2013-03-15

    The potential organic non-linear optical single crystal of L-lysine acetate has been grown by slow evaporation solution growth technique (SEST) at room temperature. It crystallizes in the monoclinic system with space group of P2(1). The crystalline perfection of the grown single crystal has been examined by high resolution X-ray diffraction analysis (HRXRD). The functional groups of the synthesized compound have been identified by (13)C NMR, (1)H NMR and FTIR analyses. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength of 236 nm. The optical band gap is found to be 5.29 eV. The steady-state PL spectra was recorded for pure L-lysine acetate crystal at room temperature. The third harmonic generation efficiency of the crystal has been evaluated by Z-scan technique and its non-linear optical coefficient has been calculated. Birefringence measurement has been carried out in order to see the optical homogeneity of the grown specimen. Its electrical properties has been assessed by dielectric measurement at different temperatures. The calculated optical band gap is 5.29 eV. Its thermal parameters like thermal diffusivity (α), thermal effusivity (e), thermal conductivity (k) and heat capacity (C(p)) have been determined by photopyroelectric technique. Vickers micro hardness studies were carried out using a Vickers hardness tester equipped with a diamond square indenter. The piezoelectric measurement for L-lysine acetate has been also been carried at ambient condition.

  9. Anisotropic Thermoelectric Properties of MnSiγ Film Prepared on R-Sapphire

    NASA Astrophysics Data System (ADS)

    Takeda, Komei; Kikuchi, Yuta; Hayashi, Kei; Miyazaki, Yuzuru; Kajitani, Tsuyoshi

    2012-05-01

    We attempted to obtain an epitaxial MnSiγ (γ˜1.7) film on R-sapphire, i.e., Sapphire(1102), substrate by pulsed laser deposition. We prepared MnSiγ films by changing the substrate temperature gradient. It was found that the MnSiγ film, whose temperature gradient in a substrate is parallel to Sapphire[1120], could be grown epitaxially on the substrate. The epitaxial relationship was MnSiγ(1000)[0010] ∥ Sapphire(1102)[1120]. The thermoelectric properties of the epitaxial MnSiγ film were different in the a- and c-axes, reflecting the anisotropic MnSiγ crystal structure. The anisotropic thermoelectric properties are discussed in terms of the electronic structure.

  10. Control algorithms of liquid crystal phased arrays used as adaptive optic correctors

    NASA Astrophysics Data System (ADS)

    Dayton, David; Gonglewski, John; Browne, Stephen

    2006-08-01

    Multi-segment liquid crystal phased arrays have been demonstrated as adaptive optics elements for correction of atmospheric turbulence. High speed dual-frequency nematic liquid crystal has sufficient bandwidth to keep up with moderate atmospheric Greenwood frequencies. However the segmented piston correction only spatial nature of the devices requires novel approaches to control algorithms especially when used with Shack-Hartmann wave front sensors. In this presentation we explore approaches and their effects on closed loop Strehl ratios. A Zernike modal based approach has produced the best results. The presentation will contain results from experiments with a Meadowlark optics liquid crystal device.

  11. Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

    NASA Astrophysics Data System (ADS)

    Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.

    2012-06-01

    Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

  12. Growth and characterization of a third order nonlinear optical single crystal: Ethylenediamine-4-nitrophenolate monohydrate

    SciTech Connect

    Dhanalakshmi, B.; Ponnusamy, S.; Muthamizhchelvan, C.; Subhashini, V.

    2015-10-15

    Highlights: • EDA4NPH crystal possesses negative nonlinear refractive index. • The crystal exhibits high third-order NLO susceptibility. • Wide transparency of the crystal makes it suitable for NLO applications. • Dielectric studies substantiate the suitability for electro-optic applications. • The crystal possesses suitable mechanical strength for device fabrication. - Abstract: Bulk crystals of the charge-transfer complex, ethylenediamine-4-nitrophenolate monohydrate, were grown by slow solvent evaporation method from aqueous solution at room temperature. The X-ray diffraction measurements showed that the crystal belongs to centrosymmetric space group C2/c of monoclinic system. The functional groups in the complex were identified using FTIR, FTRaman and FTNMR analyses. The Z-scan measurements revealed the negative nonlinear refractive index of the crystal. The nonlinear absorption coefficient and third order nonlinear optical susceptibility calculated from the measurements were −3.5823 × 10{sup −3} cm/W and 2.3762 × 10{sup −6} esu respectively. The crystal was shown to be highly transparent above 366 nm by UV–vis spectroscopy and a yellow fluorescence was observed from PL spectrum. The TG–DTA and DSC analyses showed that the crystal is thermally stable up to 117.4 °C. The crystals were characterized by dielectric, etching and microhardness studies.

  13. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    NASA Technical Reports Server (NTRS)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  14. Generation of the "perfect" optical vortex using a liquid-crystal spatial light modulator.

    PubMed

    Ostrovsky, Andrey S; Rickenstorff-Parrao, Carolina; Arrizón, Víctor

    2013-02-15

    We introduce the concept of the perfect optical vortex whose dark hollow radius does not depend on the topological charge. It is shown analytically and experimentally that such a vortex can be approximately generated in the Fourier transforming optical system with a computer-controlled liquid-crystal spatial light modulator.

  15. Formation of contour optical traps using a four-channel liquid crystal focusing device

    SciTech Connect

    Korobtsov, A V; Kotova, S P; Losevsky, N N; Mayorova, A M; Samagin, S A

    2014-12-31

    The capabilities and specific features of the formation and dynamic control of so-called contour optical traps using a fourchannel liquid crystal modulator are studied theoretically and experimentally. Circular, elliptical and C-shaped traps are formed. Trapping and confinement of absorbing micro-objects by the formed traps are demonstrated. (optical traps)

  16. Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Wang, Shuai; Feng, Lungang; Xiong, Han; Su, Xilin; Yun, Feng

    2016-07-01

    Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ˜20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

  17. Optical and structural properties of chalcone NLO single crystals

    NASA Astrophysics Data System (ADS)

    Rajesh Kumar, P. C.; Ravindrachary, V.; Janardhana, K.; Manjunath, H. R.; Karegouda, Prakash; Crasta, Vincent; Sridhar, M. A.

    2011-11-01

    Organic compound (E)-1-(4-methoxyphenyl)-3-(2,3,5-trichlorophenyl)prop-2-en-1-one [MPTCPP] with molecular formula C 16H 11Cl 3O 2 was synthesized using Claisen-Schmidt condensation reaction method. 1H NMR spectra was recorded to identify the various functional groups present in the compound and confirm the chemical structure. The single crystals were grown using slow evaporation solution growth technique. The UV-Visible spectrum study reveals that the crystal is transparent in the entire visible region and the absorption is observed at 364 nm. The Kurtz powder second harmonic generation (SHG) test shows that the MPTCPP is NLO active and its SHG efficiency is three times that of urea. Single crystal XRD study shows that the compound crystallizes in the monoclinic system with a space group Cc. The corresponding lattice parameters of the crystal are a = 28.215(5) Å, b = 3.9740(4) Å, c = 16.178(3) Å and V = 1503.0(4) Å 3. The micro hardness test was carried out and the work hardening coefficient value ( n) of the crystal was found to be 1.48. This indicates that the crystal is hard and is suitable for device application. The thermal study reveals that the thermal stability of the crystal is good.

  18. Study on optical properties of L-valine doped ADP crystal

    NASA Astrophysics Data System (ADS)

    Shaikh, R. N.; Anis, Mohd.; Shirsat, M. D.; Hussaini, S. S.

    2015-02-01

    Single crystal of L-valine doped ammonium dihydrogen phosphate has been grown by slow evaporation method at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction technique. The different functional groups of the grown crystal were identified using Fourier transform infrared analysis. The UV-visible studies were employed to examine the high optical transparency and influential optical constants for tailoring materials suitability for optoelectronics applications. The cutoff wavelength of the title crystal was found to be 280 nm with wide optical band gap of 4.7 eV. The dielectric measurements were carried to determine the dielectric constant and dielectric loss at room temperature. The grown crystal has been characterized by thermogravimetric analysis. The second harmonic generation efficiency of the grown crystal was determined by the classical Kurtz powder technique and it is found to be 1.92 times that of potassium dihydrogen phosphate. The grown crystal was identified as third order nonlinear optical material employing Z-scan technique using He-Ne laser operating at 632.8 nm.

  19. Recent development of doubly curved crystal focusing optics and their applications for micro XRF

    NASA Astrophysics Data System (ADS)

    Chen, Zewu

    1999-11-01

    Three-dimensional focusing of x-rays can be achieved by doubly-curved crystals through diffraction from a small laboratory x-ray source. Recently it has been demonstrated that an intense monochromatic x-ray microprobe can be obtained with the use of a doubly-curved mica crystal. Due to monochromatic excitation using doubly-curved crystal optics, exceptionally low background has been demonstrated in the application to micro x-ray fluorescence (MXRF). Low background and high intensity gain significantly improve the detection limit for MXRF. In this paper, the focusing and diffraction properties of a doubly-curved Johann point-focusing crystal optic for Cu K(alpha) x-rays from a microfocus x-ray source is presented. Experimental data on spot size, beam intensity, effect of source position for the optics, and MXRF spectra are discussed.

  20. Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals.

    PubMed

    Vinothkumar, P; Rajeswari, K; Kumar, R Mohan; Bhaskaran, A

    2015-06-15

    Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies. PMID:25766476

  1. Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals

    NASA Astrophysics Data System (ADS)

    Vinothkumar, P.; Rajeswari, K.; Kumar, R. Mohan; Bhaskaran, A.

    2015-06-01

    Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies.

  2. Growth of High Quality AlN Single Crystals and Their Optical Properties

    NASA Astrophysics Data System (ADS)

    Strassburg, M.; Senawiratne, J.; Dietz, N.; Haboeck, U.; Hoffmann, A.; Noveski, V.; Dalmau, R.; Schlesser, R.; Sitar, Z.

    2005-06-01

    Growth and optical properties of high quality AlN single crystals grown by physical vapor transport using powder sublimation is presented. Crystallinity, incorporated impurities and their effects on the optical properties are evaluated for different crucible materials and growth environments. A significant reduction of impurity incorporation was achieved using a two-step growth process in a TaN crucible. Crystal defects and the effect of incorporated impurities on the optical properties have been analyzed by their characteristic photoluminescence and absorption, Raman- and glow discharge mass spectroscopy.

  3. Growth and optical characterizations on 3-aminophenol perchlorate (3-AMPP) crystal

    SciTech Connect

    Boopathi, K. Ramasamy, P.

    2014-04-24

    A single crystal of organic nonlinear optical material 3-aminophenol perchlorate (3-AMP) was successfully grown by the slow evaporation solution method. Single-crystal X-ray diffractrometer was utilized to measure unit cell parameters and to confirm lattice parameter. 3-aminophenol perchlorate belongs to monoclinic space group P2{sub 1}. The optical transparency window in the UV-vis-NIR region is found to be good for nonlinear optical applications second harmonic studies were carried out. The second harmonic output intensity was tested using the Kurtz and Perry powder method and was found to be 1.1 times that of potassium dihydrogen phosphate (KDP)

  4. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    PubMed

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  5. Growth and characterization of Cadmium Thiosemicarbazide Bromide crystals for antibacterial and nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Thomas Joseph Prakash, J.; Martin Sam Gnanaraj, J.

    2015-01-01

    Semiorganic nonlinear optical crystals of Cadmium Thiosemicarbazide Bromide was grown by slow evaporation solution growth technique. The unit cell parameters were estimated by subjecting the crystals to single crystal X-ray diffraction. The grown crystals were subjected to Powder X-ray diffraction for analyzing the crystalline nature of the sample. FTIR studies reveal the functional groups and the optical characters were analyzed by UV-Vis spectral studies. Mechanical stability of the sample was assessed by Vicker's micro hardness test. The presence of surface dislocations was identified by chemical etching technique. Antibacterial study was carried out against ACDP declared harmful pathogens. SHG efficiency of CTSB crystal was tested using Nd: YAG laser and it was found to be ∼1.8 times that of potassium dihydrogen phosphate.

  6. Optical simulation of quantum algorithms using programmable liquid-crystal displays

    SciTech Connect

    Puentes, Graciana; La Mela, Cecilia; Ledesma, Silvia; Iemmi, Claudio; Paz, Juan Pablo; Saraceno, Marcos

    2004-04-01

    We present a scheme to perform an all optical simulation of quantum algorithms and maps. The main components are lenses to efficiently implement the Fourier transform and programmable liquid-crystal displays to introduce space dependent phase changes on a classical optical beam. We show how to simulate Deutsch-Jozsa and Grover's quantum algorithms using essentially the same optical array programmed in two different ways.

  7. A study of the optical and thermal properties of nonlinear mercury thiogallate crystals

    SciTech Connect

    Badikov, Valerii V; Kuzmin, Nikolai V; Laptev, Vladimir B; Malinovsky, Aleksandr L; Ryabov, Evgenii A; Mitin, Konstantin V; Nazarov, Gennadii S; Seryogin, A M; Schebetova, Nadezhda I

    2004-05-31

    The technology of growing mercury thiogallate crystals (HgGa{sub 2}S{sub 4}) is improved and high-quality bulk samples are produced. The basic optical and thermal properties of these crystals are studied. The transmission spectra of mercury thiogallate are measured and its nonlinear characteristics such as the quadratic susceptibility, tuning curves, and the optical-damage resistance are also determined. The specific heat and thermal conductivity of HgGa{sub 2}S{sub 4} are measured. It is concluded that the combined properties of HgGa{sub 2}S{sub 4} crystals can provide for them a leading position among the materials used in nonlinear-optical devices for mid-IR-frequency conversion. (nonlinear optical phenomena)

  8. Stray Light Correction in the Optical Spectroscopy of Crystals

    PubMed Central

    Hendler, Richard W.; Meuse, Curtis W.; Gallagher, Travis; Labahn, Joerg; Kubicek, Jan; Smith, Paul D.; Kakareka, John W.

    2015-01-01

    It has long been known in spectroscopy that light not passing through a sample, but reaching the detector (i.e., stray light), results in a distortion of the spectrum known as absorption flattening. In spectroscopy with crystals, one must either include such stray light or take steps to exclude it. In the former case, the derived spectra are not accurate. In the latter case, a significant amount of the crystal must be masked off and excluded. In this paper, we describe a method that allows use of the entire crystal by correcting the distorted spectrum. PMID:26688880

  9. Comment on the paper: "Crystal growth and spectroscopic characterization of Aloevera amino acid added lithium sulfate monohydrate: a non-linear optical crystal".

    PubMed

    Srinivasan, Bikshandarkoil R

    2015-01-01

    The title paper (Manimekalai et al., 2014) reports a slow evaporation solution growth of a so called 'Aloevera amino acid added lithium sulfate monohydrate' (AALSMH) crystal. In this communication, many points of criticism, concerning the crystal growth, NMR spectrum and X-ray powder pattern of this so called AALSMH nonlinear optical crystal are highlighted.

  10. Microwave Frequency Discriminator With Sapphire Resonator

    NASA Technical Reports Server (NTRS)

    Santiago, David G.; Dick, G. John

    1994-01-01

    Cooled sapphire resonator provides ultralow phase noise. Apparatus comprises microwave oscillator operating at nominal frequency of about 8.1 GHz, plus frequency-discriminator circuit measuring phase fluctuations of oscillator output. One outstanding feature of frequency discriminator is sapphire resonator serving as phase reference. Sapphire resonator is dielectric ring resonator operating in "whispering-gallery" mode. Functions at room temperature, but for better performance, typically cooled to operating temperature of about 80 K. Similar resonator described in "Sapphire Ring Resonator for Microwave Oscillator" (NPO-18082).

  11. Growth, spectral, optical, and dielectric studies on novel semiorganic NLO single crystal: d-phenylglycine hydrochloride

    NASA Astrophysics Data System (ADS)

    Uma, B.; Sakthi Murugesan, K.; Jayavel, R.; Krishnan, S.; Boaz, B. Milton

    2014-05-01

    Good quality novel semiorganic nonlinear optical single crystal of d-phenylglycine hydrochloride has been grown from the aqueous solution by low temperature solution growth method. X-ray diffraction reveals that the crystal crystallises into orthorhombic system with noncentrosymmetric space group P212121. Experimental parameters are evaluated based on single-crystal XRD and the calculated values of the polarisability were compared with the values of polarisability using Clausius-Mossotti equation. The functional groups present in the grown crystal were confirmed by Fourier transform infrared spectral analysis. The 1H and 13C FT-NMR has been recorded to elucidate the molecular structure. Ultraviolet-visible-near infra-red absorption studies on this crystal reveal that the minimum absorption region is around 228 nm. The optical band gap of the crystal was found to be 2.9 eV. The scanning electron microscope study has been carried out to determine the surface morphology of the grown crystal. Photoluminescence studies show that the material emits violet fluorescence. Thermal studies bring forth that the crystal is thermally stable up to 255 °C. Dielectric studies reveal that both the dielectric constant and dielectric loss decrease with the increase in frequency as like the typical semiorganic nonlinear optical crystals such as bisthiourea zinc chloride, bisthiourea cadmium chloride and l-arginine dihydrogen phosphate. Electrical conductivity measurements were carried out and the Arrhenius plot is used to determine the value of activation energy. The Kurtz powder analysis on the crystal confirms the existence of second harmonic generation properties. The SHG efficiency was found to be 1.15 times that of KDP crystal.

  12. A Program For Optics of Curved Crystal Neutron Spectrometers.

    1990-04-26

    Version 00 TRAX computes the resolution matrix and characteristic line widths and intensities for three-axis slow-neutron spectrometers with flat or curved, mosaic or perfect crystals, with or without Soller collimators or limiting diaphragms.

  13. Magneto-optical properties of biogenic photonic crystals in algae

    SciTech Connect

    Iwasaka, M.; Mizukawa, Y.

    2014-05-07

    In the present study, the effects of strong static magnetic fields on the structural colors of the cell covering crystals on a microalgae, coccolithophore, were investigated. The coccolithophore, Emiliania huxleyi, generates a precise assembly of calcite crystals called coccoliths by biomineralization. The coccoliths attached to the cells exhibited structural colors under side light illumination, and the colors underwent dynamic transitions when the magnetic fields were changed between 0 T and 5 T, probably due to diamagnetically induced changes of their inclination under the magnetic fields. The specific light-scattering property of individual coccoliths separated from the cells was also observed. Light scattering from a condensed suspension of coccoliths drastically decreased when magnetic fields of more than 4 T were applied parallel to the direction of observation. The magnetically aligned cell-covering crystals of the coccolithophores exhibited the properties of both a photonic crystal and a minimum micromirror.

  14. Efficient optical parametric generation in an organomineral crystal

    NASA Astrophysics Data System (ADS)

    Samuel, I. D. W.; Villacampa, B.; Josse, D.; Khodja, S.; Zyss, J.

    1995-04-01

    Organomineral crystals are engineered to combine the favorable properties of organic and inorganic materials. High gain parametric emission and amplification at telecommunications wavelengths are demonstrated in an organomineral crystal, 2-amino-5-nitropyridinium-dihydrogen phosphate. A novel angle-noncritical type-II phase-matching configuration is observed in parametric emission, and parametric amplification is demonstrated at 1.5 μm.

  15. Anomalously temperature-independent birefringence in biaxial optical crystals

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2000-01-31

    Temperature-independent birefringence in a biaxial crystal was predicted theoretically and observed experimentally for the first time. The width of the plot against temperature (the range corresponding to the temperature independence of the birefringence) at a fundamental radiation wavelength of 632.8 nm in a KTP crystal 5.9 mm long was more than 160{sup 0}C. (letters to the editor)

  16. Boundary layer elasto-optic switching in ferroelectric liquid crystals

    NASA Technical Reports Server (NTRS)

    Parmar, D. S.

    1992-01-01

    The first experimental observation of a change in the director azimuthal angle due to applied shear stress is reported in a sample configuration involving a liquid-crystal-coated top surface exposed directly to gas flow. The electrooptic response caused by the shear stress is large, fast, and reversible. These findings are relevant to the use of liquid crystals in boundary layer investigations on wind tunnel models.

  17. Growth and studies of cyclohexylammonium 4-methoxy benzoate single crystal for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Sathya, P.; Gopalakrishnan, R.

    2015-06-01

    Cyclohexylammonium 4-Methoxy Benzoate (C4MB) was synthesised and the functional groups were confirmed by FTIR analysis. The purified C4MB (by repeated recrystallisation) was used for single crystal growth. Single crystal of cyclohexylammonium 4-methoxy benzoate was successfully grown by slow evaporation solution growth method at ambient temperature. Structural orientations were determined from single crystal X-ray diffractometer. Optical absorption and cut off wavelength were identified by UV-Visible spectroscopy. Thermal stability of the crystal was studied from thermogravimetric and differential thermal analyses curves. Mechanical stability of the grown crystal was analysed by Vicker's microhardness tester. The Second Harmonic Generation (SHG) study revealed that the C4MB compound exhibits the SHG efficiency 3.3 times greater than KDP crystal.

  18. Growth and studies of cyclohexylammonium 4-methoxy benzoate single crystal for nonlinear optical applications

    SciTech Connect

    Sathya, P.; Gopalakrishnan, R.

    2015-06-24

    Cyclohexylammonium 4-Methoxy Benzoate (C4MB) was synthesised and the functional groups were confirmed by FTIR analysis. The purified C4MB (by repeated recrystallisation) was used for single crystal growth. Single crystal of cyclohexylammonium 4-methoxy benzoate was successfully grown by slow evaporation solution growth method at ambient temperature. Structural orientations were determined from single crystal X-ray diffractometer. Optical absorption and cut off wavelength were identified by UV-Visible spectroscopy. Thermal stability of the crystal was studied from thermogravimetric and differential thermal analyses curves. Mechanical stability of the grown crystal was analysed by Vicker’s microhardness tester. The Second Harmonic Generation (SHG) study revealed that the C4MB compound exhibits the SHG efficiency 3.3 times greater than KDP crystal.

  19. Growth and characterization of bis-glycine sodium nitrate (BGSN), a novel semi-organic nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Sankar, R.; Ragahvan, C. M.; Mohan Kumar, R.; Jayavel, R.

    2007-11-01

    Single crystals of bis-glycine sodium nitrate (BGSN), a semi-organic nonlinear optical (NLO) material, have been grown by slow cooling method. Good optical quality single crystals with dimensions up to 1.6×1.6×1.0 cm 3 are obtained. Using a single-crystal diffractometer, the morphology of BGSN crystal was identified. Powder X-ray diffraction confirms the crystalline nature of BGSN. The grown crystals were characterized by optical transmission spectrum (UV) and FTIR studies. The NLO property of the crystal was confirmed by Kurtz second harmonic generation (SHG) test, and the output power generated by the crystal was compared with that of KDP. The thermal stability of the crystal was studied by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Micro hardness study was carried out for different planes, and the anisotropy behavior of the crystal was observed.

  20. Optical anisotropy induced by torsion stresses in LiNbO3 crystals: appearance of an optical vortex.

    PubMed

    Skab, Ihor; Vasylkiv, Yurij; Savaryn, Viktoriya; Vlokh, Rostyslav

    2011-04-01

    We report the results of studies of the torsion effect on the optical birefringence in LiNbO(3) crystals. We found that the twisting of those crystals causes a birefringence distribution revealing nontrivial peculiarities. In particular, they have a special point at the center of the cross section perpendicular to the torsion axis where the zero birefringence value occurs. It has also been ascertained that the surface of the spatial birefringence distribution has a conical shape, with the cone axis coinciding with the torsion axis. We revealed that an optical vortex, with a topological charge equal to unity, appears under the torsion of LiNbO(3) crystals. It has been shown that, in contrast to the q plate, both the efficiency of spin-orbital coupling and the orbital momentum of the emergent light can be operated by the torque moment.

  1. Structural, optical and dielectric studies of novel non-linear Bisglycine Lithium Nitrate piezoelectric single crystal

    NASA Astrophysics Data System (ADS)

    Dalal, Jyoti; Sinha, Nidhi; Kumar, Binay

    2014-11-01

    The novel non-linear semiorganic Bisglycine Lithium Nitrate (BGLiN) single crystals were grown by slow evaporation technique. The structural analysis revealed that it belongs to non-centrosymmetric orthorhombic structure. The presence of various functional groups in the grown crystal was confirmed by FTIR and Raman analysis. Surface morphology of the grown crystal was studied by scanning electron microscopy. The optical studies show that crystal has good transmittance (more than 80%) in the entire visible region and a wide band gap (5.17 eV). The optical constants such as extinction coefficient (K), the reflectance (R) and refractive index (n) as a function of photon energy were calculated from the optical measurements. With the help of these optical constants the electric susceptibility (χc) and both the real (εr) and imaginary (εi) parts of the dielectric constants were also calculated which are required to develop optoelectronic devices. In photoluminescence studies, a broad emission band centered at 404 nm was found in addition to a small band at 352 nm. A broad transition (from 29 to 33 °C) was observed with low dielectric constant value. A high piezoelectric charge coefficient (d33) of 14 pC/N was measured at room temperature which implies its usefulness for various sensor applications. The second harmonic generation efficiency of crystal was found to be 1.5 times to that of KDP. From thermo gravimetric analysis and differential thermal analysis, thermal stability and melting point (246 °C) were investigated. The dielectric behavior, optical characterization, piezoelectric behavior and the non-linear optical properties of the Bisglycine Lithium Nitrate single crystals were reported for the first time which established the usefulness of these crystals for various piezo- and opto-electronics applications.

  2. Laser damage threshold and nonlinear optical properties of large aperture elements of YCOB crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yanqing; Wu, Anhua; Gao, Pan; Tu, Xiaoniu; Liang, Xiaoyan; Hou, Jing; Yang, Liming; Wang, Tao; Qian, Liejia; Shi, Erwei

    2012-01-01

    Large size of YCa4O(BO3)3(YCOB) crystals were grown both by Czochralski and Bridgman methods. Large size elements as large as 60 mm clear aperture were cut and polished with surface flatness of 1/5 wavelength. Optical homogeneity of YCOB crystal was found in the order of 10-6. Laser damage thresholds of several YCOB crystal elements were tested using different laser facilities with different pulse widths or wavelengths, with thresholds varied from 0.8 GW/cm2 to more than 1 TW/cm2. One SHG and two optical parametric chirped-pulse amplification (OPCPA) experiments were executed to characterize the nonlinear optical properties of YCOB crystals and the quality of the crystals. The results shown that YCOB had good performance in OPCPA application, especially with low content of parameter florescence. Combined with good NLO performance and possibility to grow large size crystals, YCOB crystal was a good choice for high power OPCPA applications.

  3. Laser damage threshold and nonlinear optical properties of large aperture elements of YCOB crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yanqing; Wu, Anhua; Gao, Pan; Tu, Xiaoniu; Liang, Xiaoyan; Hou, Jing; Yang, Liming; Wang, Tao; Qian, Liejia; Shi, Erwei

    2011-11-01

    Large size of YCa4O(BO3)3(YCOB) crystals were grown both by Czochralski and Bridgman methods. Large size elements as large as 60 mm clear aperture were cut and polished with surface flatness of 1/5 wavelength. Optical homogeneity of YCOB crystal was found in the order of 10-6. Laser damage thresholds of several YCOB crystal elements were tested using different laser facilities with different pulse widths or wavelengths, with thresholds varied from 0.8 GW/cm2 to more than 1 TW/cm2. One SHG and two optical parametric chirped-pulse amplification (OPCPA) experiments were executed to characterize the nonlinear optical properties of YCOB crystals and the quality of the crystals. The results shown that YCOB had good performance in OPCPA application, especially with low content of parameter florescence. Combined with good NLO performance and possibility to grow large size crystals, YCOB crystal was a good choice for high power OPCPA applications.

  4. Growth and spectroscopic, thermodynamic and nonlinear optical studies of L-threonine phthalate crystal

    NASA Astrophysics Data System (ADS)

    Theras, J. Elberin Mary; Kalaivani, D.; Jayaraman, D.; Joseph, V.

    2015-10-01

    L-threonine phthalate (LTP) single crystal has been grown using a solution growth technique at room temperature. Single crystal X-ray diffraction analysis reveals that LTP crystallizes in monoclinic crystal system with space group C2/c. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength 309 nm. The optical band gap is found to be 4.05 eV. The functional groups of the synthesized compound have been identified by FTIR spectral analysis. The functional groups present in the material were also confirmed by FT-RAMAN spectroscopy. Surface morphology and the presence of various elements were studied by SEM-EDAX analysis. The thermal stability of LTP single crystal has been analyzed by TGA/DTA studies. The thermodynamic parameters such as activation energy, entropy, enthalpy and Gibbs free energy were determined for the grown material using TG data and Coats-Redfern relation. Since the grown crystal is centrosymmetric, Z-Scan studies were carried out for analyzing the third order nonlinear optical property. The nonlinear absorption coefficient, nonlinear refractive index and susceptibility have been measured using Z-Scan technique.

  5. Crystal orientation dependent optical transmittance and band gap of Na0.5Bi0.5TiO3-BaTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    He, Chongjun; Deng, Chenguang; Wang, Jiming; Gu, Xiaorong; Wu, Tong; Zhu, Kongjun; Liu, Youwen

    2016-02-01

    Optical transmittance spectra of lead-free ferroelectric (1-x)Na0.5Bi0.5TiO3-xBaTiO3 (NBT-xBT) single crystals poled along different directions have been studied comprehensively. After poled along [001] direction, the transmittance of tetragonal NBT-8%BT crystal is about 70%, which is much higher than that of NBT-2%BT crystal with rhombohedral structure and NBT-5%BT crystal with morphotropic phase boundary (MPB) composition. However, after poled [111] direction, the transmittance of tetragonal NBT-8%BT crystal is the smallest among them. These properties are manifest in view of the crystal structure. Both direct and indirect optical energy band gaps, as well phonon energies were obtained from absorption coefficient spectra by Tauc equations. The band gaps of [001]-poled NBT-xBT crystals increase with BT content, yet the [111]-poled crystals have opposite trends.

  6. Polymer stabilized liquid crystals: Topology-mediated electro-optical behavior and applications

    NASA Astrophysics Data System (ADS)

    Weng, Libo

    There has been a wide range of liquid crystal polymer composites that vary in polymer concentration from as little as 3 wt.% (polymer stabilized liquid crystal) to as high as 60 wt.% (polymer dispersed liquid crystals). In this dissertation, an approach of surface polymerization based on a low reactive monomer concentration about 1 wt.% is studied in various liquid crystal operation modes. The first part of dissertation describes the development of a vertical alignment (VA) mode with surface polymer stabilization, and the effects of structure-performance relationship of reactive monomers (RMs) and polymerization conditions on the electro-optical behaviors of the liquid crystal device has been explored. The polymer topography plays an important role in modifying and enhancing the electro-optical performance of stabilized liquid crystal alignment. The enabling surface-pinned polymer stabilized vertical alignment (PSVA) approach has led to the development of high-performance and fast-switching displays with controllable pretilt angle, increase in surface anchoring energy, high optical contrast and fast response time. The second part of the dissertation explores a PSVA mode with in-plane switching (IPS) and its application for high-efficiency and fast-switching phase gratings. The diffraction patterns and the electro-optical behaviors including diffraction efficiency and response time are characterized. The diffraction grating mechanism and performance have been validated by computer simulation. Finally, the advantages of surface polymerization approach such as good optical contrast and fast response time have been applied to the fringe-field switching (FFS) system. The concentration of reactive monomer on the electro-optical behavior of the FFS cells is optimized. The outstanding electro-optical results and mechanism of increase in surface anchoring strength are corroborated by the director field simulation. The density and topology of nanoscale polymer protrusions

  7. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  8. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    PubMed Central

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  9. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    NASA Astrophysics Data System (ADS)

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-07-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  10. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  11. GaN grown on nano-patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Jing, Kong; Meixin, Feng; Jin, Cai; Hui, Wang; Huaibing, Wang; Hui, Yang

    2015-04-01

    High-quality gallium nitride (GaN) film was grown on nano-patterned sapphire substrates (NPSS) and investigated using XRD and SEM. It was found that the optimum thickness of the GaN buffer layer on the NPSS is 15 nm, which is thinner than that on micro-patterned sapphire substrates (MPSS). An interesting phenomenon was observed for GaN film grown on NPSS:GaN mainly grows on the trench regions and little grows on the sidewalls of the patterns at the initial growth stage, which is dramatically different from GaN grown on MPSS. In addition, the electrical and optical properties of LEDs grown on NPSS were characterized. Project supported by the Suzhou Nanojoin Photonics Co., Ltd and the High-Tech Achievements Transformation of Jiangsu Province, China (No.BA2012010).

  12. Ti:sapphire laser with long-pulse lamp pumping

    NASA Astrophysics Data System (ADS)

    Koselja, Michael P.; Kubelka, Jiri; Kvapil, Jiri

    1992-06-01

    Lamp pumping of Ti:Sapphire has some advantages over laser pumping and represents some interest due to possible applications. The paper will present laser behavior of Ti:Sapphire under very long lamp pulse pumping. Pulse lamp duration (FWHM) was more than 100 times greater than the lifetime of Ti3+. Output energy with no tuning element was achieved greater than 1.5 J with 0.12% electrical-to-optical efficiency. Dimensions of the rod used was 7 mm in diameter and 148 mm in length. The doping level of Ti3+ was 0.09% Ti2O3 in the rod. Tuning characteristics with different tuning elements are also presented. Further development to obtain CW lamp pumping operation will be discussed.

  13. Flux growth of yttrium calcium oxy borate (YCOB) single crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Arun Kumar, R.; Dhanasekaran, R.

    2009-01-01

    Nonlinear optical single crystals of YCa 4O(BO 3) 3 (YCOB) with good optical quality were grown from boron-tri-oxide flux for the first time. Polycrystalline YCOB samples were synthesized from the solid-state reaction method. Optimum conditions for the growth of YCOB crystals from the flux were determined. Single crystals of YCOB with dimensions 10×5×5 mm 3 were obtained by the method of 'slow cooling'. The grown crystals were characterized by XRD, UV-vis-NIR, and Fourier transform infrared (FTIR) studies. The powder XRD pattern reveals the formation of YCOB compound. The lattice parameters were identified through single crystal XRD studies. The UV-vis-NIR results show that the crystal has a sharp cutoff at 220 nm and is nearly 78% transparent over a wide wavelength range enabling it for applications in the UV region. The functional groups belonging to the YCOB single crystals were identified by the FTIR results. The primary emphasis is laid to describe 'flux technique' as an alternative method to grow YCOB single crystals. The results are presented and discussed.

  14. Studies on optical properties of pure and Mg2+ doped ZTS single crystal

    NASA Astrophysics Data System (ADS)

    Sumithra Devi, M.; Arthi, A. P.; Thamizharasan, K.

    2014-09-01

    Single crystal of semiorganic nonlinear optical material of pure and Mg2+ doped ZTS were grown by slow evaporation technique from its aqueous solution. The grown crystal was characterized by single crystal XRD to determine the cell parameters. The Mg2+ doped was characterized by SEM and EDX spectrum. The chemical composition of both the pure ZTS and doped Mg2+ crystals were determined by Fourier transform infrared (FTIR). The optical absorption spectrum recorded in the wavelength was ranged from 200 to 2500 nm and its energy gap (Eg) for both pure ZTS is 4.47 eV and doped Mg2+ is 4.42 eV. The mechanical strength of the grown crystal was found from Vicker's microhardness measurements. It showed that pure and doped ZTS crystals are soft in nature. The dielectric measurement was carried out to study the different polarization mechanism and conductivity of the crystal. Photoconductivity studies revealed that the positive photoconductivity of the both were considered as grown crystals.

  15. Accurate Optical Detection of Amphiphiles at Liquid-Crystal-Water Interfaces

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth K.; Jákli, Antal

    2014-04-01

    Liquid-crystal-based biosensors utilize the high sensitivity of liquid-crystal alignment to the presence of amphiphiles adsorbed to one of the liquid-crystal surfaces from water. They offer inexpensive, easy optical detection of biologically relevant molecules such as lipids, proteins, and cells. Present techniques use linear polarizers to analyze the alignment of the liquid crystal. The resulting images contain information not only about the liquid-crystal tilt with respect to the surface normal, the quantity which is controlled by surface adsorption, but also on the uncontrolled in-plane liquid-crystal alignment, thus making the detection largely qualitative. Here we show that detecting the liquid-crystal alignment between circular polarizers, which are only sensitive to the liquid-crystal tilt with respect to the interface normal, makes possible quantitative detection by measuring the transmitted light intensity with a spectrophotometer. Following a new procedure, not only the concentration dependence of the optical path difference but also the film thickness and the effective birefringence can be determined accurately. We also introduce a new "dynamic" mode of sensing, where (instead of the conventional "steady" mode, which detects the concentration dependence of the steady-state texture) we increase the concentration at a constant rate.

  16. Optical, mechanical and thermal characterization of l-threonine single crystals grown in dimethyl urea solution

    NASA Astrophysics Data System (ADS)

    Shanthi, A.; Krishnan, C.; Selvarajan, P.

    2013-09-01

    An organic material of a noncentrosymmetric l-threonine single crystal was grown in a dimethyl urea solution using the slow evaporation method. The grown crystal was transparent and colorless, with a size of about 20 × 7 × 4 mm3, obtained within a period of 10 days. The grown crystal was subjected to various studies, such as x-ray diffraction (XRD), Fourier transform infrared (FTIR), microhardness, ultraviolet-visible (UV-Vis) transmittance, thermogravimetric analysis and differential thermal analysis (TGA/DTA) and second harmonic generation (SHG). l-threonine crystals grown in a dimethyl urea solution show relative SHG efficiency of 0.92 times that of potassium dihydrogen phosphate. The functional groups of the crystals have been confirmed by FTIR analysis. The mechanical strength of the crystal was estimated by the Vickers hardness test. The lattice parameters of the grown crystal were determined by single crystal XRD and powder XRD studies, and the diffraction peaks were indexed. A UV-Vis spectrum was recorded in the wavelength range of 200-1100 nm to find the suitability of the crystal for nonlinear optical applications. The thermal stability of l-threonine crystal grown in dimethyl urea was checked using the TGA/DTA analysis.

  17. In situ observation of elementary growth processes of protein crystals by advanced optical microscopy.

    PubMed

    Sazaki, Gen; Van Driessche, Alexander E S; Dai, Guoliang; Okada, Masashi; Matsui, Takuro; Otálora, Fermin; Tsukamoto, Katsuo; Nakajima, Kazuo

    2012-07-01

    To start systematically investigating the quality improvement of protein crystals, the elementary growth processes of protein crystals must be first clarified comprehensively. Atomic force microscopy (AFM) has made a tremendous contribution toward elucidating the elementary growth processes of protein crystals and has confirmed that protein crystals grow layer by layer utilizing kinks on steps, as in the case of inorganic and low-molecular-weight compound crystals. However, the scanning of the AFM cantilever greatly disturbs the concentration distribution and solution flow in the vicinity of growing protein crystals. AFM also cannot visualize the dynamic behavior of mobile solute and impurity molecules on protein crystal surfaces. To compensate for these disadvantages of AFM, in situ observation by two types of advanced optical microscopy has been recently performed. To observe the elementary steps of protein crystals noninvasively, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) was developed. To visualize individual mobile protein molecules, total internal reflection fluorescent (TIRF) microscopy, which is widely used in the field of biological physics, was applied to the visualization of protein crystal surfaces. In this review, recent progress in the noninvasive in situ observation of elementary steps and individual mobile protein molecules on protein crystal surfaces is outlined.

  18. Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique

    NASA Astrophysics Data System (ADS)

    Prakash, M.; Geetha, D.; Lydia Caroline, M.

    2013-04-01

    Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

  19. Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique.

    PubMed

    Prakash, M; Geetha, D; Lydia Caroline, M

    2013-04-15

    Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

  20. Cost effective fabrication method for large sapphire sensor windows

    NASA Astrophysics Data System (ADS)

    Walters, Mark; Gould, Alan; Bartlett, Kevin; Brophy, Matthew R.; DeGroote Nelson, Jessica

    2013-09-01

    Sapphire poses very difficult challenges to optical manufacturers due to its high hardness and anisotropic properties. These challenges can result in long lead times and high prices. Large optical sensor windows demand much higher precision surfaces compared to transparent armor (windshields) to achieve acceptable image quality. Optimax is developing a high speed, cost effective process to produce such windows. The Optimax high speed process is a two-step process that combines precision fixed abrasive grinding and high speed polishing. In-house studies have demonstrated cycle time reduction of up to 6X as compared to conventional processing.

  1. Nonlinear optical response of a two-dimensional atomic crystal.

    PubMed

    Merano, Michele

    2016-01-01

    The theory of Bloembergen and Pershan for the light waves at the boundary of nonlinear media is extended to a nonlinear two-dimensional (2D) atomic crystal, i.e., a single planar atomic lattice, placed between linear bulk media. The crystal is treated as a zero-thickness interface, a real 2D system. Harmonic waves emanate from it. Generalization of the laws of reflection and refraction give the direction and the intensity of the harmonic waves. As a particular case that contains all the essential physical features, second-order harmonic generation is considered. The theory, due to its simplicity that stems from the special character of a single planar atomic lattice, is able to elucidate and explain the rich experimental details of harmonic generation from a 2D atomic crystal.

  2. Dual frequency liquid crystal devices for infrared electro-optical applications

    NASA Astrophysics Data System (ADS)

    Gu, Dong-Feng; Winker, Bruce K.; Taber, Donald B.; Cheung, Jeffrey T.; Lu, Yiwei; Kobrin, Paul H.; Zhuang, Zhiming

    2002-12-01

    A dual frequency liquid crystal (DFLC) can be field-driven towards its unperturbed state, which dramatically reduces the overall electro-optical response time. DFLC materials with sub-millisecond switching speed are being used in infrared electro-optical devices at wavelengths up to 3 microns. The performance of devices such as tunable half-wave plates and optical phased arrays in agile beam steering devices, and wavefront controllers for adaptive optics are described. Device issues discussed include drive schemes, field of view, reflective direct drive backplane, infrared-transparent conductors, and antireflection coatings.

  3. Dielectric and optical investigations of ferroelectric modes in chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Kuczynski, Wojciech; Hoffmann, Jerzy; Malecki, J.

    1995-08-01

    Optical methods of detection of ferroelectric modes are described in detail and compared with the dielectric method. The advantages of both methods are discussed. It is concluded that the dielectric method is simple whereas the optical method is more sensitive. The optical response is free of the background steaming from nonferroelectric polarization mechanisms which are always present in the dielectric reponse. The realxation of the Goldstone- and soft modes in a room temperature ferroelectric liquid crystal has been investigated using dielectric and optical methods. Both methods have given concordant results.

  4. Simple system for measuring optical rotation of glucose solution using liquid-crystal grating

    NASA Astrophysics Data System (ADS)

    Honma, Michinori; Uchida, Etsuo; Saito, Hiroo; Harada, Takeshi; Muto, Seiei; Nose, Toshiaki

    2015-12-01

    We demonstrate an optical system for measuring the concentrations of optically active media using liquid-crystal polarization gratings (LCPGs). The optical rotation angle is determined by measuring the intensities of two diffracted light beams from an LCPG combined with a quarter-wave plate (QWP). The intensity ratio is used to evaluate the optical rotation angle, minimizing the dependence on changes in light source intensity and wavelength and reducing the influence of temperature-drift-induced LC birefringence shifts. We demonstrate the system by measuring the concentration of a glucose-water solution. The measurement error caused by the slight wavelength dependence of the QWP’s retardation is assessed numerically.

  5. Optical flip-flops and sequential logic circuits using a liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Fatehi, M. T.; Collins, S. A., Jr.; Wasmundt, K. C.

    1984-01-01

    This paper is concerned with the application of optics to digital computing. A Hughes liquid crystal light valve is used as an active optical element where a weak light beam can control a strong light beam with either a positive or negative gain characteristic. With this device as the central element the ability to produce bistable states from which different types of flip-flop can be implemented is demonstrated. In this paper, some general comments are first presented on digital computing as applied to optics. This is followed by a discussion of optical implementation of various types of flip-flop. These flip-flops are then used in the design of optical equivalents to a few simple sequential circuits such as shift registers and accumulators. As a typical sequential machine, a schematic layout for an optical binary temporal integrator is presented. Finally, a suggested experimental configuration for an optical master-slave flip-flop array is given.

  6. Magneto-optical switching of Bloch surface waves in magnetophotonic crystals

    NASA Astrophysics Data System (ADS)

    Romodina, M. N.; Soboleva, I. V.; Fedyanin, A. A.

    2016-10-01

    Bloch-surface-wave (BSW) excitation controlled by Faraday rotation in one-dimensional magnetophotonic crystals is presented. Dispersion curves of the Bloch surface wave and waveguide modes of magnetophotonic crystals consisting of silicon dioxide and bismuth-substituted yttrium-iron-garnet (Bi:YIG) quarter-wavelength-thick layers are calculated using Berreman's 4×4 transfer matrix method. Enhanced Faraday rotation observed in the magnetophotonic crystals in the spectral vicinity of the BSW resonance enables the magneto-optical switching of BSWs. The excitation of the BSWs at the magnetophotonic crystal surface for p-polarized incident light is induced by magneto-optical activity in the Bi:YIG layers.

  7. Controlling the volatility of the written optical state in electrochromic DNA liquid crystals.

    PubMed

    Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y; Polyakov, Alexey O; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T M; Clark, Noel A; Herrmann, Andreas

    2016-05-09

    Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

  8. Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

    2016-05-01

    Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

  9. Optical surface wave in a crystal with diffusion photorefractive nonlinearity

    SciTech Connect

    Chetkin, S A; Akhmedzhanov, I M

    2011-11-30

    We consider a steady-state nonlinear photorefractive surface wave (PR SW) with TE or TM polarisation when the refractive index of the photorefractive crystal (PRC) depends on the strength of the diffusion crystal electric field emerging upon the wave propagation. We have determined the phase trajectory and transverse structure of the PR SW intensity distribution for different values of the diffusion photorefractive nonlinearity. We have investigated a photorefractive diffraction grating, which arises in the surface PRC layer during propagation of the nonlinear PR SW.

  10. Structural, magnetic and optical properties of two concomitant molecular crystals

    NASA Astrophysics Data System (ADS)

    Silva, Manuela Ramos; Milne, Bruce; Coutinho, Joana T.; Pereira, Laura C. J.; Martín-Ramos, Pablo; Pereira da Silva, Pedro S.; Martín-Gil, Jesús

    2016-03-01

    A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Cu(II) ions assemble in alternating chains with Cu … Cu distances of 2.5685(4) and 3.1760(4) Å. The temperature dependence of the magnetic susceptibility reveals an antiferromagnetic interaction between the paddle-wheel copper centers with an exchange of -300 cm-1. The exchange integral was also determined by quantum chemical ab-initio calculations, using polarised and unpolarised basis sets reproducing well the experimental value. The second harmonic generation efficiency of a concomitantly crystallized material was evaluated and was found to be comparable to urea.

  11. Electrically modulated transparent liquid crystal -optical grating projection.

    PubMed

    Buss, Thomas; Smith, Cameron L C; Kristensen, Anders

    2013-01-28

    A transparent, fully integrated electrically modulated projection technique is presented based on light guiding through a thin liquid crystal layer covering sub-wavelength gratings. The reported device operates at 10 V with response times of 4.5 ms. Analysis of the liquid crystal alignment shows that director-reorientation occurs over timescales on the order of 90 µs close to the grating surface. The technology is suitable for next generation heads-up-displays and reconfigurable multilayer photonic integrated circuits. PMID:23389166

  12. High magneto-optical characteristics of Holmium-doped terbium gallium garnet crystal.

    PubMed

    Chen, Zhe; Yang, Lei; Wang, Xiangyong; Yin, Hang

    2016-06-01

    Magneto-optical characteristics of a new magneto-active material, (Tb(1-x)Hox)3Ga5O12 crystal, have been grown by the Czochralski (Cz) method. A high value of the Verdet constant was obtained at room temperature-namely, 214.9 and 77.8  rad·m-1 T-1 for 632.8 and 1064 nm, respectively. The Verdet constant of the Ho-doped terbium gallium garnet crystal at 1064 nm is about 2 times higher than that of terbium gallium garnet crystal. High value of magneto-optical figure-of-merit makes it an attractive next-generation magneto-optics material for high-power Faraday isolators.

  13. High magneto-optical characteristics of Holmium-doped terbium gallium garnet crystal.

    PubMed

    Chen, Zhe; Yang, Lei; Wang, Xiangyong; Yin, Hang

    2016-06-01

    Magneto-optical characteristics of a new magneto-active material, (Tb(1-x)Hox)3Ga5O12 crystal, have been grown by the Czochralski (Cz) method. A high value of the Verdet constant was obtained at room temperature-namely, 214.9 and 77.8  rad·m-1 T-1 for 632.8 and 1064 nm, respectively. The Verdet constant of the Ho-doped terbium gallium garnet crystal at 1064 nm is about 2 times higher than that of terbium gallium garnet crystal. High value of magneto-optical figure-of-merit makes it an attractive next-generation magneto-optics material for high-power Faraday isolators. PMID:27244419

  14. Photonic Crystals-Inhibited Spontaneous Emission: Optical Antennas-Enhanced Spontaneous Emission

    NASA Astrophysics Data System (ADS)

    Yablonovitch, Eli

    Photonic crystals are also part of everyday technological life in opto-electronic telecommunication devices that provide us with internet, cloud storage, and email. But photonic crystals have also been identified in nature, in the coloration of peacocks, parrots, chameleons, butterflies and many other species.In spite of its broad applicability, the original motivation of photonic crystals was to create a ``bandgap'' in which the spontaneous emission of light would be inhibited. Conversely, the opposite is now possible. The ``optical antenna'' can accelerate spontaneous emission. Over 100 years after the radio antenna, we finally have tiny ``optical antennas'' which can act on molecules and quantum dots. Employing optical antennas, spontaneous light emission can become faster than stimulated emission.

  15. Electro-optical control in a plasmonic metamaterial hybridised with a liquid-crystal cell.

    PubMed

    Buchnev, O; Ou, J Y; Kaczmarek, M; Zheludev, N I; Fedotov, V A

    2013-01-28

    We experimentally demonstrate efficient electro-optical control in an active nano-structured plasmonic metamaterial hybridised with a liquid-crystal cell. The hybridisation was achieved by simultaneously replacing the polarizer, transparent electrode and molecular alignment layer of the liquid-crystal cell with the metamaterial nano-structure. With the control signal of only 7 V we have achieved a fivefold hysteresis-free modulation of metamaterial transmission at the wavelength of 1.55 µm.

  16. A versatile low-cost Czochralski crystal growth system for nonlinear optical organic materials

    NASA Technical Reports Server (NTRS)

    Aggarwal, M. D.; Wang, W. S.; Shields, Angela W.; Penn, Benjamin G.; Frazier, Donald O.

    1992-01-01

    A versatile low-cost Czochralski system for pulling crystals from melt has been described. It is designed for low melting, transparent, and nonlinear optical materials. One of the most important novel feature of this crystal growth system is that the entire growth process including the solid-liquid interface can be viewed from any direction. Another is the use of an after-heater to reduce excess heat loss from the surface of the melt.

  17. Electro-optical control in a plasmonic metamaterial hybridised with a liquid-crystal cell.

    PubMed

    Buchnev, O; Ou, J Y; Kaczmarek, M; Zheludev, N I; Fedotov, V A

    2013-01-28

    We experimentally demonstrate efficient electro-optical control in an active nano-structured plasmonic metamaterial hybridised with a liquid-crystal cell. The hybridisation was achieved by simultaneously replacing the polarizer, transparent electrode and molecular alignment layer of the liquid-crystal cell with the metamaterial nano-structure. With the control signal of only 7 V we have achieved a fivefold hysteresis-free modulation of metamaterial transmission at the wavelength of 1.55 µm. PMID:23389148

  18. Investigations on the vibrational modes and non-linear optical properties of 4-Fluoro Chalcone crystal

    NASA Astrophysics Data System (ADS)

    Prabu, S.; Nagalakshmi, R.; Balaji, J.; Srinivasan, P.

    2014-08-01

    Organic Nonlinear Optical (NLO) crystals of 4-fluorochalcone (4FC) were synthesized and grown by slow evaporation solution growth method. The grown crystals have been characterised by powder X-ray diffraction, factor group analysis, FTIR, FT-Raman, UV-Vis Spectroscopy, powder SHG and Vickers microhardness tests. Theoretical quantum chemical analysis were performed to determine the first order hyperpolarizability (β) and HOMO-LUMO analysis of the title compound were computed by GAUSSIAN 03 package.

  19. Optical nonlinearities near single photon level with a quantum dot coupled to a photonic crystal cavity

    NASA Astrophysics Data System (ADS)

    Sridharan, Deepak

    Over the last decade, exponential increase of information bandwidth over the internet and other communication media has increased the total power consumed by the devices associated with information exchange. With ever increasing number of users, and packing of a higher number of devices onto a chip, there is a great need for reduction in not only the power consumption of the devices but also the costs associated with information transfer. Currently, the benchmark in the energy consumption per logic operation is at femtojoule level and is set by the CMOS industry. However, optical devices based on single photon emitters coupled to a microcavity have the potential to reduce the optical power dissipation down to attojoule levels wherein only few 10s of photons are consumed for a logic operation. This work presents our theoretical and experimental efforts towards realization of all optical device based on the enhanced nonlinearities of a single photon emitter in a photonic crystal cavity. We show that a single quantum dot coupled to a photonic crystal cavity can be used to route an incoming optical beam with optical power dissipation of 14 attojoules, corresponding to only 65 photons. This value is well below the operational level for current CMOS devices indicating the potential for chip based optical transistors for reduction in energy consumption. The single photon emitters that we use to create the nonlinearity are the quantum dots, which are semiconductor nanostructures that exhibit a discrete energy spectrum. The interaction of the quantum dot, with light confined inside a photonic crystal cavity, results in strong atom-photon interactions which can be used for ultra-low power all optical switching. The strong interactions between a quantum dot and photonic crystal cavity can be further utilized to realize quantum computation schemes on a chip. I also describe techniques for integrating this transistor into an optical circuit, and discuss methods for post

  20. Experimental analysis of sapphire contact probes for Nd-YAG laser angioplasty.

    PubMed

    Ashley, S; Brooks, S G; Gehani, A A; Kester, R C; Rees, M R

    1990-06-01

    Laser angioplasty may offer percutaneous recanalization of occluded vessels where conventional guidewire and balloon techniques fail. Metal laser thermal angioplasty probes may, however, cause excessive thermal damage due to high tip temperatures (greater than 400.C). Therefore, contact probes made from artificial sapphire crystal designed for general laser surgery are currently being evaluated for use in laser angioplasty with continuous wave Nd-YAG energy. The sapphire modifies the laser energy in various ways, and this paper examines the physical characteristics of five types of rounded sapphire probe (SMTR, MTR, MTRL, OS, LT) and how these properties are affected by clinical usage. The laser beam profile emitted by these probes demonstrates a focal spot 1-2 mm in front of the tip. However, the forward transmission of Nd-YAG energy through the sapphires varied (SMTR, 85%; MTR, 83%; MTRL, 75%; OS, 54%; LT, 69%). Probe heating occurs owing to energy absorption within the sapphire. The surface temperature of the sapphires was measured in air by infrared thermography and the hottest region within the probes localized by an isothermographic technique. At energy settings used clinically (20 J, 10 watts for 2 s) the SMTR, MTR, and MTRL probes exhibited higher temperature rises (94-112.C) than the OS and LT probes (30.C), and heating was localized to the front surface of the former probes. Peak sapphire temperatures remained lower than those of metal probes even at higher energies. After clinical use, the MTR probe demonstrated reduced transmission, beam defocusing, and increased heating, due to surface pitting. Thus, recanalization with sapphire probes occurs by a combination of photothermal and contact thermal effects that are localized to the probe tip and may reduce the degree of thermal injury associated with metal probes. Understanding these basic properties is important to the application and development of contact probes for laser recanalization. PMID:2142867