Science.gov

Sample records for nonlinear optical imaging

  1. Coherent nonlinear optical imaging: beyond fluorescence microscopy.

    PubMed

    Min, Wei; Freudiger, Christian W; Lu, Sijia; Xie, X Sunney

    2011-01-01

    The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy (including stimulated Raman scattering and two-photon absorption) and pump-probe microscopy (including excited-state absorption, stimulated emission, and ground-state depletion), provides new image contrasts for nonfluorescent species. Thanks to the high-frequency modulation transfer scheme, these imaging techniques exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles and excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques. PMID:21453061

  2. Coherent Nonlinear Optical Imaging: Beyond Fluorescence Microscopy

    PubMed Central

    Min, Wei; Freudiger, Christian W.; Lu, Sijia; Xie, X. Sunney

    2012-01-01

    The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy, including stimulated Raman scattering and two photon absorption, and pump-probe microscopy, including stimulated emission, excited state absorption and ground state depletion, provide distinct and powerful image contrasts for non-fluorescent species. Thanks to high-frequency modulation transfer scheme, they exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles, excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques. PMID:21453061

  3. Nonlinear Optical Image Processing with Bacteriorhodopsin Films

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Deiss, Ron (Technical Monitor)

    1994-01-01

    The transmission properties of some bacteriorhodopsin film spatial light modulators are uniquely suited to allow nonlinear optical image processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude transmission feature of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. The bacteriorhodopsin film displays the logarithmic amplitude response for write beam intensities spanning a dynamic range greater than 2.0 orders of magnitude. We present experimental results demonstrating the principle and capability for several different image and noise situations, including deterministic noise and speckle. Using the bacteriorhodopsin film, we successfully filter out image noise from the transformed image that cannot be removed from the original image.

  4. Nonlinear optical microscopy for imaging thin films and surfaces

    SciTech Connect

    Smilowitz, L.B.; McBranch, D.W.; Robinson, J.M.

    1995-03-01

    We have used the inherent surface sensitivity of second harmonic generation to develop an instrument for nonlinear optical microscopy of surfaces and interfaces. We have demonstrated the use of several nonlinear optical responses for imaging thin films. The second harmonic response of a thin film of C{sub 60} has been used to image patterned films. Two photon absorption light induced fluorescence has been used to image patterned thin films of Rhodamine 6G. Applications of nonlinear optical microscopy include the imaging of charge injection and photoinduced charge transfer between layers in semiconductor heterojunction devices as well as across membranes in biological systems.

  5. Nonlinear optical imaging: toward chemical imaging during neurosurgery

    NASA Astrophysics Data System (ADS)

    Meyer, Tobias; Dietzek, Benjamin; Krafft, Christoph; Romeike, Bernd F. M.; Reichart, Rupert; Kalff, Rolf; Popp, Jürgen

    2011-03-01

    Tumor recognition and precise tumor margin detection presents a central challenge during neurosurgery. In this contribution we present our recent all-optical approach to tackle this problem. We introduce various nonlinear optical techniques, such as coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG) and two-photon fluorescence (TPEF), to study the morphology and chemical composition of (ex vivo) brain tissue. As the experimental techniques presented are contact-free all-optical techniques, which do not rely on the administration of external (fluorescence) labels, we anticipate that their implementation into surgical microscopes will provide significant advantages of intraoperative tumor diagnosis. In this contribution an introduction to the different optical spectroscopic methods will be presented and their implementation into a multimodal microscopic setup will be discussed. Furthermore, we will exemplify their application to brain tissue, i.e. both pig brain as a model for healthy brain tissue and human brain samples taken from surgical procedures. The data to be discussed show the capability of a joint CARS/SHG/TPEF multimodal imaging approach in highlighting various aspects of tissue morphochemistry. The consequences of this microspectroscopic potential, when combined with the existing technology of surgical microscopes, will be discussed.

  6. Development of a nonlinear optical measurement-4 coherent imaging system

    NASA Astrophysics Data System (ADS)

    Chen, Xiaojun; Song, Yinglin; Gu, Jihua; Yang, Junyi; Shui, Min; Hou, Dengke; Zhu, Zongjie

    2009-07-01

    After the nonlinear optical phenomena were discovered, people began to research the techniques to detect the optical nonlinearities of materials. In this paper, a new optical nonlinear measurement technique-4f coherent imaging system is recommended. The system has many advantages: single shot real-time measurement, simple experimental apparatus, high sensitivity, being able to detect the magnitude and sign of both nonlinear absorption and refraction at the same time, low requirement of beam spatial distribution, and so on. This paper introduces the theory of the 4f system and makes a detailed review and expounds development and application of the 4f coherent image system. The nerve of the experiment is improving the phase diaphragm. The shape of the diaphragm from the double-slits to the small rectangular object, and transition to a circular aperture, finally forming a circular phase diaphragm, which is a circular aperture in the center add a phase object. Following these diaphragm changes, the sensitivity of the system is greatly improved. The latest developments of the system are series-wound double 4f coherent imaging technique and the time-resolved pump-probe system based on NIT-PO. The time-resolved pump-probe system based on NIT-PO can be used to measure the dynamic characteristics of excited states nonlinear absorption and refraction.

  7. Image segmentation by nonlinear filtering of optical Hough transform.

    PubMed

    Fernández, Ariel; Flores, Jorge L; Alonso, Julia R; Ferrari, José A

    2016-05-01

    The identification and extraction (i.e., segmentation) of geometrical features is crucial in many tasks requiring image analysis. We present a method for the optical segmentation of features of interest from an edge enhanced image. The proposed method is based on the nonlinear filtering (implemented by the use of a spatial light modulator) of the generalized optical Hough transform and is capable of discriminating features by shape and by size. The robustness of the method against noise in the input, low contrast, or overlapping of geometrical features is assessed, and experimental validation of the working principle is presented. PMID:27140381

  8. Optical authentication via photon-synthesized ghost imaging using optical nonlinear correlation

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Chen, Xudong

    2015-10-01

    We present a method for optical authentication via photon-synthesized ghost imaging using optical nonlinear correlation. In ghost imaging, multiple series of photons recorded at the object beam arm can be arbitrarily controlled for the generation of synthesized objects. Ghost imaging with sparse reference intensity patterns provides a channel to effectively modulate the noise-like synthesized objects during the recovery, and the reconstructed (noise-like) objects, i.e., added or subtracted information, can be further authenticated by optical nonlinear correlation algorithm. It is expected that the proposed method can provide an effective and promising alternative for ghost-imaging-based optical processing.

  9. Nonlinear Interferometric Vibrational Imaging (NIVI) with Novel Optical Sources

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.; King, Matthew D.; Liu, Yuan; Tu, Haohua; Gruebele, Martin

    Optical imaging is essential in medicine and in fundamental studies of biological systems. Although many existing imaging modalities can supply valuable information, not all are capable of label-free imaging with high-contrast and molecular specificity. The application of molecular or nanoparticle contrast agents may adversely influence the biological system under investigation. These substances also present ongoing concerns over toxicity or particle clearance, which must be properly addressed before their approval for in vivo human imaging. Hence there is an increasing appreciation for label-free imaging techniques. It is of primary importance to develop imaging techniques that can indiscriminately identify and quantify biochemical compositions to high degrees of sensitivity and specificity through only the intrinsic optical response of endogenous molecular species. The development and use of nonlinear interferometric vibrational imaging, which is based on the interferometric detection of optical signals from coherent anti-Stokes Raman scattering (CARS), along with novel optical sources, offers the potential for label-free molecular imaging.

  10. Nonlinear optical imaging characteristics in rat tail tendon

    NASA Astrophysics Data System (ADS)

    Liu, N. R.; Zhang, X. Z.; Qiu, Y. S.; Chen, R.

    2013-04-01

    The aim of this study was to examine the characteristics of skeletal muscle fibers in tail tendons, explore the content of intrinsic components at different depths and ascertain the optimum excitation wavelength, which will help to establish a relationship between diagnosis and therapy and the tendon injury. A multiphoton microscopic imaging system was used to achieve the images and spectra via an imaging mode and a Lambda mode, respectively. This work demonstrates that the skeletal muscle fibers of the tail tendon are in good order. Second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals originating from certain intrinsic components are varied with depth, and the SHG/TPEF intensity ratios are varied at different excitation wavelengths. Below 800 nm is the optimum for cell TPEF, while above 800 nm is the optimum for SHG. With the development of imaging techniques, a nonlinear optical imaging system will be helpful to represent the functional behaviors of tissue related to tendon injury.

  11. Second-Order Nonlinear Optical Imaging of Chiral Crystals

    PubMed Central

    Kissick, David J.; Wanapun, Debbie; Simpson, Garth J.

    2012-01-01

    Second-order nonlinear optical imaging of chiral crystals (SONICC) is an emerging technique for crystal imaging and characterization. We provide a brief overview of the origin of second harmonic generation signals in SONICC and discuss recent studies using SONICC for biological applications. Given that they provide near-complete suppression of any background, SONICC images can be used to determine the presence or absence of protein crystals through both manual inspection and automated analysis. Because SONICC creates high-resolution images, nucleation and growth kinetics can also be observed. SONICC can detect metastable, homochiral crystalline forms of amino acids crystallizing from racemic solutions, which confirms Ostwald’s rule of stages for crystal growth. SONICC’s selectivity, based on order, and sensitivity, based on background suppression, make it a promising technique for numerous fields concerned with chiral crystal formation. PMID:21469954

  12. Label-free nonlinear optical imaging of mouse retina

    PubMed Central

    He, Sicong; Ye, Cong; Sun, Qiqi; Leung, Christopher K.S.; Qu, Jianan Y.

    2015-01-01

    A nonlinear optical (NLO) microscopy system integrating stimulated Raman scattering (SRS), two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) was developed to image fresh mouse retinas. The morphological and functional details of various retinal layers were revealed by the endogenous NLO signals. Particularly, high resolution label-free imaging of retinal neurons and nerve fibers in the ganglion cell and nerve fiber layers was achieved by capturing endogenous SRS and TPEF signals. In addition, the spectral and temporal analysis of TPEF images allowed visualization of different fluorescent components in the retinal pigment epithelium (RPE). Fluorophores with short TPEF lifetime, such as A2E, can be differentiated from other long-lifetime components in the RPE. The NLO imaging method would provide important information for investigation of retinal ganglion cell degeneration and holds the potential to study the biochemical processes of visual cycle in the RPE. PMID:25798325

  13. Molecular probes for nonlinear optical imaging of biological membranes

    NASA Astrophysics Data System (ADS)

    Blanchard-Desce, Mireille H.; Ventelon, Lionel; Charier, Sandrine; Moreaux, Laurent; Mertz, Jerome

    2001-12-01

    Second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) are nonlinear optical (NLO) phenomena that scale with excitation intensity squared, and hence give rise to an intrinsic 3-dimensional resolution when used in microscopic imaging. TPEF microscopy has gained widespread popularity in the biology community whereas SHG microscopy promises to be a powerful tool because of its sensitivity to local asymmetry. We have implemented an approach toward the design of NLO-probes specifically adapted for SHG and/or TPEF imaging of biological membranes. Our strategy is based on the design of nanoscale amphiphilic NLO-phores. We have prepared symmetrical bolaamphiphilic fluorophores combining very high two-photon absorption (TPA) cross-sections in the visible red region and affinity for cellular membranes. Their incorporation and orientation in lipid membranes can be monitored via TPEF anisotropy. We have also prepared amphiphilic push-pull chromophores exhibiting both large TPA cross-sections and very large first hyperpolarizabilities in the near-IR region. These NLO-probes have proved to be particularly useful for imaging of biological membranes by simultaneous SHG and TPEF microscopy and offer attractive prospects for real-time imaging of fundamental biological processes such as adhesion, fusion or reporting of membrane potentials.

  14. Nonlinear optical Stokes ellipsometric (NOSE) microscopy for imaging the nonlinear susceptibility tensors of collagen

    NASA Astrophysics Data System (ADS)

    Dow, Ximeng Y.; DeWalt, Emma L.; Sullivan, Shane Z.; Schmitt, Paul D.; Simpson, Garth J.

    2016-03-01

    Nonlinear optical Stokes ellipsometric (NOSE) microscopy was demonstrated for the analysis of collagen structure in a mouse tail section. NOSE is based on polarization-dependent second harmonic generation (SHG) imaging. The fast polarization-modulation was achieved using an electro-optic modulator (EOM), allowing for the potential of video-rate NOSE analysis. The signal to noise advantages associated with suppression of 1/f noise by rapid polarization modulation allowed reliable recovery of the local-frame tensor on a per-pixel basis. An iterative approach involving laboratory to local frame coordinate transformation was developed to recover the spatial distribution of local-frame nonlinear susceptibility tensor elements of collagen as well as the polar and azimuthal orientation angles of the collagen structure.

  15. Scanning all-fiber-optic endomicroscopy system for 3D nonlinear optical imaging of biological tissues

    PubMed Central

    Wu, Yicong; Leng, Yuxin; Xi, Jiefeng; Li, Xingde

    2009-01-01

    An extremely compact all-fiber-optic scanning endomicroscopy system was developed for two-photon fluorescence (TPF) and second harmonic generation (SHG) imaging of biological samples. A conventional double-clad fiber (DCF) was employed in the endomicroscope for single-mode femtosecond pulse delivery, multimode nonlinear optical signals collection and fast two-dimensional scanning. A single photonic bandgap fiber (PBF) with negative group velocity dispersion at two-photon excitation wavelength (i.e. ~810 nm) was used for pulse prechirping in replacement of a bulky grating/lens-based pulse stretcher. The combined use of DCF and PBF in the endomicroscopy system made the endomicroscope basically a plug-and-play unit. The excellent imaging ability of the extremely compact all-fiber-optic nonlinear optical endomicroscopy system was demonstrated by SHG imaging of rat tail tendon and depth-resolved TPF imaging of epithelial tissues stained with acridine orange. The preliminary results suggested the promising potential of this extremely compact all-fiber-optic endomicroscopy system for real-time assessment of both epithelial and stromal structures in luminal organs. PMID:19434122

  16. Nonlinear optical microscopy in biology: Combining second-harmonic generation and two-photon fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Clays, Koen

    2011-03-01

    Optical microscopy has been since long a truly enabling visualization technique in the biological and biomedical sciences. Linear optical microscopy relies on simple linear optical effects. Nonlinear optical microscopy relies on the nonlinear optical properties of endogenous or exogenous chromophores to produce a better image. Two-photon fluorescence (TPF), a third-order nonlinear optical effect and observed at the focal spot only due to the quadratic intensity dependence, results in inherently higher resolution than possible for one-photon fluorescence, observed over the complete Rayleigh range. Second-harmonic generation (SHG) is a second-order nonlinear optical effect only observed for non-centrosymmetric arrangements of non-centrosymmetric chromophores. While this does put a restriction on the chromophores that can be used, it also results in structural information about symmetry when used in combination with TPF. TPF, being a third-order nonlinear process, is not restricted by any symmetry consideration. We will review the molecular design criteria for exogenous probes for combined SHG and TPF nonlinear microscopy, provide examples of optimized chromophores and show microscopy images demonstrating the use of such chromophores in nonlinear microscopy.

  17. Direct optical imaging of graphene in vitro by nonlinear femtosecond laser spectral reshaping.

    PubMed

    Li, Baolei; Cheng, Yingwen; Liu, Jie; Yi, Congwen; Brown, April S; Yuan, Hsiangkuo; Vo-Dinh, Tuan; Fischer, Martin C; Warren, Warren S

    2012-11-14

    Nonlinear optical microscopy, based on femtosecond laser spectral reshaping, characterized and imaged graphene samples made from different methods, both on slides and in a biological environment. This technique clearly discriminates between graphene flakes with different numbers of layers and reveals the distinct nonlinear optical properties of reduced graphene oxide as compared to mechanically exfoliated or chemical vapor deposition grown graphene. The nonlinearity makes it applicable to scattering samples (such as tissue) as opposed to previous methods, such as transmission. This was demonstrated by high-resolution imaging of breast cancer cells incubated with graphene flakes. PMID:23101475

  18. Nonlinear optical methods for cellular imaging and localization.

    PubMed

    McVey, A; Crain, J

    2014-07-01

    Of all the ways in which complex materials (including many biological systems) can be explored, imaging is perhaps the most powerful because delivering high information content directly. This is particular relevant in aspects of cellular localization where the physical proximity of molecules is crucial in biochemical processes. A great deal of effort in imaging has been spent on enabling chemically selective imaging so that only specific features are revealed. This is almost always achieved by adding fluorescent chemical labels to specific molecules. Under appropriate illumination conditions only the molecules (via their labels) will be visible. The technique is simple and elegant but does suffer from fundamental limitations: (1) the fluorescent labels may fade when illuminated (a phenomenon called photobleaching) thereby constantly decreasing signal contrast over the course of image acquisition. To combat photobleaching one must reduce observation times or apply unfavourably low excitation levels all of which reduce the information content of images; (2) the fluorescent species may be deactivated by various environmental factors (the general term is fluorescence quenching); (3) the presence of fluorescent labels may introduce unexpected complications or may interfere with processes of interest (4) Some molecules of interest cannot be labelled. In these circumstances we require a fundamentally different strategy. One of the most promising alternative is based on a technique called Coherent Anti-Stokes Raman scattering (CARS). CARS is a fundamentally more complex process than is fluorescence and the experimental procedures and optical systems required to deliver high quality CARS images are intricate. However, the rewards are correspondingly very high: CARS probes the chemically distinct vibrations of the constituent molecules in a complex system and is therefore also chemically selective as are fluorescence-based methods. Moreover,the potentially severe problems of

  19. Nonlinear optical imaging characteristics of colonic adenocarcinoma using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Nenrong; Chen, Rong; Li, Hongsheng; Chen, Jianxin

    2012-12-01

    Multiphoton microscopy (MPM), a noninvasive optical method with high resolution and high sensitivity, can obtain detailed microstructures of biotissues at submolecular level. In this study, MPM is used to image microstructure varieties of human colonic mucosa and submucosa with adenocarcinoma. Some parameters, such as gland configuration, SHG/TPEF intensity ratio, and collagen orientation and so on, should serve the indicators of early colorectal cancer. The exploratory results show that it's potential for the development of multiphoton mini-endoscopy in real-time early diagnosis of colorectal cancer.

  20. Interferometric and nonlinear-optical spectral-imaging techniques for outer space and live cells

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuyoshi

    2015-12-01

    Multidimensional signals such as the spectral images allow us to have deeper insights into the natures of objects. In this paper the spectral imaging techniques that are based on optical interferometry and nonlinear optics are presented. The interferometric imaging technique is based on the unified theory of Van Cittert-Zernike and Wiener-Khintchine theorems and allows us to retrieve a spectral image of an object in the far zone from the 3D spatial coherence function. The retrieval principle is explained using a very simple object. The promising applications to space interferometers for astronomy that are currently in progress will also be briefly touched on. An interesting extension of interferometric spectral imaging is a 3D and spectral imaging technique that records 4D information of objects where the 3D and spectral information is retrieved from the cross-spectral density function of optical field. The 3D imaging is realized via the numerical inverse propagation of the cross-spectral density. A few techniques suggested recently are introduced. The nonlinear optical technique that utilizes stimulated Raman scattering (SRS) for spectral imaging of biomedical targets is presented lastly. The strong signals of SRS permit us to get vibrational information of molecules in the live cell or tissue in real time. The vibrational information of unstained or unlabeled molecules is crucial especially for medical applications. The 3D information due to the optical nonlinearity is also the attractive feature of SRS spectral microscopy.

  1. Imaging of matrix-disorder in normal and pathological human dermis using nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Zhuo, Shuangmu; Chen, Jianxin; Xie, Shusen; Zheng, Liqin; Jiang, Xingshan

    2009-11-01

    In dermis, collagen and elastin are important structural proteins of extracellular maxtrix. The matrix-disorder is associated with various physiologic processes, such as localized scleroderma, anetoderma, photoaging. In this work, we demonstrate the capability of nonlinear optical microscopy in imaging structural proteins in normal and pathological human dermis.

  2. Nonlinear photoinduced anisotropy and modifiable optical image display in a bacteriorhodopsin/polymer composite film

    NASA Astrophysics Data System (ADS)

    Wei, Lai; Luo, Jia; Zhu, Jiang; Lu, Ming; Zhao, You-yuan; Ma, De-wang; Ding, Jian-dong

    2007-04-01

    The nonlinear photoinduced anisotropy with large birefringence in a bacteriorhodopsin/polymer composite (bR/PC) film was observed. The contrast ratio, a ratio of the maximum to the minimum intensity of transmitted probe light through the bR/PC film within the linear gray scale range could reach ˜350:1. An all-optical image display in different colors was performed. The intensity of the transmitted signal could be modulated by adjusting the multibeam polarization states and intensities. Therefore, the positive image, negative image, and image erasure in display were demonstrated.

  3. Nonlinear coherent optical image processing using logarithmic transmittance of bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Downie, John D.

    1995-08-01

    The transmission properties of some bacteriorhodopsin-film spatial light modulators are uniquely suited to allow nonlinear optical image-processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude-transmission characteristic of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. I present experimental results demonstrating the principle and the capability for several different image and noise situations, including deterministic noise and speckle. The bacteriorhodopsin film studied here displays the logarithmic transmission response for write intensities spanning a dynamic range greater than 2 orders of magnitude.

  4. Nonlinear Coherent Optical Image Processing Using Logarithmic Transmittance of Bacteriorhodopsin Films

    NASA Technical Reports Server (NTRS)

    Downie, John D.

    1995-01-01

    The transmission properties of some bacteriorhodopsin-film spatial light modulators are uniquely suited to allow nonlinear optical image-processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude-transmission characteristic of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. I present experimental results demonstrating the principle and the capability for several different image and noise situations, including deterministic noise and speckle. The bacteriorhodopsin film studied here displays the logarithmic transmission response for write intensities spanning a dynamic range greater than 2 orders of magnitude.

  5. Nonlinear ptychographic coherent diffractive imaging.

    PubMed

    Odstrcil, M; Baksh, P; Gawith, C; Vrcelj, R; Frey, J G; Brocklesby, W S

    2016-09-01

    Ptychographic Coherent diffractive imaging (PCDI) is a significant advance in imaging allowing the measurement of the full electric field at a sample without use of any imaging optics. So far it has been confined solely to imaging of linear optical responses. In this paper we show that because of the coherence-preserving nature of nonlinear optical interactions, PCDI can be generalised to nonlinear optical imaging. We demonstrate second harmonic generation PCDI, directly revealing phase information about the nonlinear coefficients, and showing the general applicability of PCDI to nonlinear interactions. PMID:27607631

  6. Nonlinear optical microscopy and ultrasound imaging of human cervical structure

    NASA Astrophysics Data System (ADS)

    Reusch, Lisa M.; Feltovich, Helen; Carlson, Lindsey C.; Hall, Gunnsteinn; Campagnola, Paul J.; Eliceiri, Kevin W.; Hall, Timothy J.

    2013-03-01

    The cervix softens and shortens as its collagen microstructure rearranges in preparation for birth, but premature change may lead to premature birth. The global preterm birth rate has not decreased despite decades of research, likely because cervical microstructure is poorly understood. Our group has developed a multilevel approach to evaluating the human cervix. We are developing quantitative ultrasound (QUS) techniques for noninvasive interrogation of cervical microstructure and corroborating those results with high-resolution images of microstructure from second harmonic generation imaging (SHG) microscopy. We obtain ultrasound measurements from hysterectomy specimens, prepare the tissue for SHG, and stitch together several hundred images to create a comprehensive view of large areas of cervix. The images are analyzed for collagen orientation and alignment with curvelet transform, and registered with QUS data, facilitating multiscale analysis in which the micron-scale SHG images and millimeter-scale ultrasound data interpretation inform each other. This novel combination of modalities allows comprehensive characterization of cervical microstructure in high resolution. Through a detailed comparative study, we demonstrate that SHG imaging both corroborates the quantitative ultrasound measurements and provides further insight. Ultimately, a comprehensive understanding of specific microstructural cervical change in pregnancy should lead to novel approaches to the prevention of preterm birth.

  7. Far-field optical imaging with subdiffraction resolution enabled by nonlinear saturation absorption

    PubMed Central

    Ding, Chenliang; Wei, Jingsong

    2016-01-01

    The resolution of far-field optical imaging is required to improve beyond the Abbe limit to the subdiffraction or even the nanoscale. In this work, inspired by scanning electronic microscopy (SEM) imaging, in which carbon (or Au) thin films are usually required to be coated on the sample surface before imaging to remove the charging effect while imaging by electrons. We propose a saturation-absorption-induced far-field super-resolution optical imaging method (SAI-SRIM). In the SAI-SRIM, the carbon (or Au) layers in SEM imaging are replaced by nonlinear-saturation-absorption (NSA) thin films, which are directly coated onto the sample surfaces using advanced thin film deposition techniques. The surface fluctuant morphologies are replicated to the NSA thin films, accordingly. The coated sample surfaces are then imaged using conventional laser scanning microscopy. Consequently, the imaging resolution is greatly improved, and subdiffraction-resolved optical images are obtained theoretically and experimentally. The SAI-SRIM provides an effective and easy way to achieve far-field super-resolution optical imaging for sample surfaces with geometric fluctuant morphology characteristics. PMID:26727415

  8. Far-field optical imaging with subdiffraction resolution enabled by nonlinear saturation absorption

    NASA Astrophysics Data System (ADS)

    Ding, Chenliang; Wei, Jingsong

    2016-01-01

    The resolution of far-field optical imaging is required to improve beyond the Abbe limit to the subdiffraction or even the nanoscale. In this work, inspired by scanning electronic microscopy (SEM) imaging, in which carbon (or Au) thin films are usually required to be coated on the sample surface before imaging to remove the charging effect while imaging by electrons. We propose a saturation-absorption-induced far-field super-resolution optical imaging method (SAI-SRIM). In the SAI-SRIM, the carbon (or Au) layers in SEM imaging are replaced by nonlinear-saturation-absorption (NSA) thin films, which are directly coated onto the sample surfaces using advanced thin film deposition techniques. The surface fluctuant morphologies are replicated to the NSA thin films, accordingly. The coated sample surfaces are then imaged using conventional laser scanning microscopy. Consequently, the imaging resolution is greatly improved, and subdiffraction-resolved optical images are obtained theoretically and experimentally. The SAI-SRIM provides an effective and easy way to achieve far-field super-resolution optical imaging for sample surfaces with geometric fluctuant morphology characteristics.

  9. Far-field optical imaging with subdiffraction resolution enabled by nonlinear saturation absorption.

    PubMed

    Ding, Chenliang; Wei, Jingsong

    2016-01-01

    The resolution of far-field optical imaging is required to improve beyond the Abbe limit to the subdiffraction or even the nanoscale. In this work, inspired by scanning electronic microscopy (SEM) imaging, in which carbon (or Au) thin films are usually required to be coated on the sample surface before imaging to remove the charging effect while imaging by electrons. We propose a saturation-absorption-induced far-field super-resolution optical imaging method (SAI-SRIM). In the SAI-SRIM, the carbon (or Au) layers in SEM imaging are replaced by nonlinear-saturation-absorption (NSA) thin films, which are directly coated onto the sample surfaces using advanced thin film deposition techniques. The surface fluctuant morphologies are replicated to the NSA thin films, accordingly. The coated sample surfaces are then imaged using conventional laser scanning microscopy. Consequently, the imaging resolution is greatly improved, and subdiffraction-resolved optical images are obtained theoretically and experimentally. The SAI-SRIM provides an effective and easy way to achieve far-field super-resolution optical imaging for sample surfaces with geometric fluctuant morphology characteristics. PMID:26727415

  10. Nonlinear optical materials as coherence filters for noninvasive imaging through turbid media

    NASA Astrophysics Data System (ADS)

    Anderson, Denise Brown

    Noninvasive optical imaging of the internal structure of objects that are obscured by diffusive media has recently attracted interest for characterizing the internal porous structure of certain types of composite materials and for diagnostic imaging of medical or biological tissue. However, strong scattering of the optical radiation by these inhomogeneous materials can severely degrade image resolution by randomizing the optical image information in the object's transmitted or reflected optical signals. Thus, to improve image resolution, some form of gating technique is necessary to separate the minimally scattered light from the severely scattered light. A coherence gating technique based on degenerate four- wave mixing (DFWM) in thin nonlinear optical materials is described. Two-dimensional (2-D) depth-resolved imaging through a 4 mean free path (mfp) scattering media was obtained for a BaTiO3 photorefractive crystal, with an achievable depth resolution of 20 μm. In addition, a dyedoped K15 nematic liquid crystal film was used to provide for the first time single shot image acquisition through a 2 mfp scattering media, with an achievable transverse resolution of 70 μm. The direct current (DC) electric field-assisted nonlinear optical (NLO) properties of K15 were used to increase the sensitivity of the DFWM technique (i.e., increase the phase conjugate reflectivity) by one order of magnitude. The NLO characteristics of K15 liquid crystal samples under applied DC electric fields were also investigated. A birefringence experiment was used to qualitatively investigate the in-plane alignment of several liquid crystal films before and after the application of DC fields. Finally, Raman spectroscopy measurements provided evidence of the destruction of the molecular ordering of these films for increases in Rhodamine dye concentrations (from 0.15% to 0.5%). The DFWM imaging technique can be used to provide instantaneous, depth-resolved, 2-D images of the internal

  11. Multifunctional imaging of endogenous contrast by simultaneous nonlinear and optical coherence microscopy of thick tissues.

    PubMed

    Yazdanfar, Siavash; Chen, Yen Yu; So, Peter T C; Laiho, Lily H

    2007-07-01

    A variety of high resolution optical microscopy techniques have been developed in recent years for basic and clinical studies of biological systems. We demonstrate a trimodal microscope combining optical coherence microscopy (OCM) with two forms of nonlinear microscopy, namely two-photon excited fluorescence (2PF) and second harmonic generation (SHG), for imaging turbid media. OCM combines the advantages of confocal detection and coherence gating for structural imaging in highly scattering tissues. Nonlinear microscopy enables the detection of biochemical species, such as elastin, NAD(P)H, and collagen. While 2PF arises from nonlinear excitation of fluorescent species, SHG is a form of nonlinear scattering observed in materials that lack a center of inversion symmetry, such as type I collagen. Characterization of the microscope showed nearly diffraction-limited spatial resolution in all modalities. Images were obtained in fish scales and excised human skin samples. The primary endogenous sources of contrast in the dermis were due to elastin autofluorescence and collagen SHG. Multimodal microscopy allows the simultaneous visualization of structural and functional information of biological systems. PMID:17323366

  12. Screening of Protein Crystallization Trials by Second Order Nonlinear Optical Imaging of Chiral Crystals (SONICC)

    PubMed Central

    Haupert, Levi; Simpson, Garth

    2011-01-01

    Second order nonlinear optical imaging of chiral crystals (SONICC) is a promising new method for the sensitive and selective detection of protein crystals. Relevant general principles of second harmonic generation, which underpins SONICC, are reviewed. Instrumentation and methods for SONICC measurements are described and critically assessed in terms of performance trade-offs. Potential origins of false-positives and false-negatives are also discussed. PMID:22101350

  13. Imaging collagen remodeling and sensing transplanted autologous fibroblast metabolism in mouse dermis using multimode nonlinear optical imaging

    NASA Astrophysics Data System (ADS)

    Zhuo, Shuangmu; Chen, Jianxin; Cao, Ning; Jiang, Xingshan; Xie, Shusen; Xiong, Shuyuan

    2008-06-01

    Collagen remodeling and transplanted autologous fibroblast metabolic states in mouse dermis after cellular injection are investigated using multimode nonlinear optical imaging. Our findings show that the technique can image the progress of collagen remodeling in mouse dermis. It can also image transplanted autologous fibroblasts in their collagen matrix environment in the dermis, because of metabolic activity. It was also found that the approach can provide two-photon ratiometric redox fluorometry based on autologous fibroblast fluorescence from reduced nicotinamide adenine dinucleotide coenzyme and oxidized flavoproteins for sensing the autologous fibroblast metabolic state. These results show that the multimode nonlinear optical imaging technique may have potential in a clinical setting as an in vivo diagnostic and monitoring system for cellular therapy in plastic surgery.

  14. Evaluating cell matrix mechanics using an integrated nonlinear optical tweezer-confocal imaging system

    NASA Astrophysics Data System (ADS)

    Peng, Berney; Alonzo, Carlo A. C.; Xia, Lawrence; Speroni, Lucia; Georgakoudi, Irene; Soto, Ana M.; Sonnenschein, Carlos; Cronin-Golomb, Mark

    2013-09-01

    Biomechanics plays a central role in breast epithelial morphogenesis. In this study we have used 3D cultures in which normal breast epithelial cells are able to organize into rounded acini and tubular ducts, the main structures found in the breast tissue. We have identified fiber organization as a main determinant of ductal organization. While bulk rheological properties of the matrix seem to play a negligible role in determining the proportion of acini versus ducts, local changes may be pivotal in shape determination. As such, the ability to make microscale rheology measurements coupled with simultaneous optical imaging in 3D cultures can be critical to assess the biomechanical factors underlying epithelial morphogenesis. This paper describes the inclusion of optical tweezers based microrheology in a microscope that had been designed for nonlinear optical imaging of collagen networks in ECM. We propose two microrheology methods and show preliminary results using a gelatin hydrogel and collagen/Matrigel 3D cultures containing mammary gland epithelial cells.

  15. Imaging arterial cells, atherosclerosis, and restenosis by multimodal nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Han-Wei; Simianu, Vlad; Locker, Matthew J.; Sturek, Michael; Cheng, Ji-Xin

    2008-02-01

    By integrating sum-frequency generation (SFG), and two-photon excitation fluorescence (TPEF) on a coherent anti-Stokes Raman scattering (CARS) microscope platform, multimodal nonlinear optical (NLO) imaging of arteries and atherosclerotic lesions was demonstrated. CARS signals arising from CH II-rich membranes allowed visualization of endothelial cells and smooth muscle cells in a carotid artery. Additionally, CARS microscopy allowed vibrational imaging of elastin and collagen fibrils which are rich in CH II bonds in their cross-linking residues. The extracellular matrix organization was further confirmed by TPEF signals arising from elastin's autofluorescence and SFG signals arising from collagen fibrils' non-centrosymmetric structure. The system is capable of identifying different atherosclerotic lesion stages with sub-cellular resolution. The stages of atherosclerosis, such as macrophage infiltration, lipid-laden foam cell accumulation, extracellular lipid distribution, fibrous tissue deposition, plaque establishment, and formation of other complicated lesions could be viewed by our multimodal CARS microscope. Collagen percentages in the region adjacent to coronary artery stents were resolved. High correlation between NLO and histology imaging evidenced the validity of the NLO imaging. The capability of imaging significant components of an arterial wall and distinctive stages of atherosclerosis in a label-free manner suggests the potential application of multimodal nonlinear optical microscopy to monitor the onset and progression of arterial diseases.

  16. Linear and Non-Linear Optical Imaging of Cancer Cells with Silicon Nanoparticles.

    PubMed

    Tolstik, Elen; Osminkina, Liubov A; Akimov, Denis; Gongalsky, Maksim B; Kudryavtsev, Andrew A; Timoshenko, Victor Yu; Heintzmann, Rainer; Sivakov, Vladimir; Popp, Jürgen

    2016-01-01

    New approaches for visualisation of silicon nanoparticles (SiNPs) in cancer cells are realised by means of the linear and nonlinear optics in vitro. Aqueous colloidal solutions of SiNPs with sizes of about 10-40 nm obtained by ultrasound grinding of silicon nanowires were introduced into breast cancer cells (MCF-7 cell line). Further, the time-varying nanoparticles enclosed in cell structures were visualised by high-resolution structured illumination microscopy (HR-SIM) and micro-Raman spectroscopy. Additionally, the nonlinear optical methods of two-photon excited fluorescence (TPEF) and coherent anti-Stokes Raman scattering (CARS) with infrared laser excitation were applied to study the localisation of SiNPs in cells. Advantages of the nonlinear methods, such as rapid imaging, which prevents cells from overheating and larger penetration depth compared to the single-photon excited HR-SIM, are discussed. The obtained results reveal new perspectives of the multimodal visualisation and precise detection of the uptake of biodegradable non-toxic SiNPs by cancer cells and they are discussed in view of future applications for the optical diagnostics of cancer tumours. PMID:27626408

  17. Organic nonlinear optical materials

    NASA Technical Reports Server (NTRS)

    Umegaki, S.

    1987-01-01

    Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.

  18. Nonlinear Optics and Applications

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  19. Multimodal nonlinear optical imaging of atherosclerotic plaque development in myocardial infarction-prone rabbits

    NASA Astrophysics Data System (ADS)

    Ko, Alex C. T.; Ridsdale, Andrew; Smith, Michael S. D.; Mostaço-Guidolin, Leila B.; Hewko, Mark D.; Pegoraro, Adrian F.; Kohlenberg, Elicia K.; Schattka, Bernie; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

    2010-03-01

    Label-free imaging of bulk arterial tissue is demonstrated using a multimodal nonlinear optical microscope based on a photonic crystal fiber and a single femtosecond oscillator operating at 800 nm. Colocalized imaging of extracellular elastin fibers, fibrillar collagen, and lipid-rich structures within aortic tissue obtained from atherosclerosis-prone myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits is demonstrated through two-photon excited fluorescence, second harmonic generation, and coherent anti-Stokes Raman scattering, respectively. These images are shown to differentiate healthy arterial wall, early atherosclerotic lesions, and advanced plaques. Clear pathological changes are observed in the extracellular matrix of the arterial wall and correlated with progression of atherosclerotic disease as represented by the age of the WHHLMI rabbits.

  20. Estimating the risk of squamous cell cancer induction in skin following nonlinear optical imaging.

    PubMed

    Thomas, Giju; Nadiarnykh, Oleg; van Voskuilen, Johan; Hoy, Christopher L; Gerritsen, Hans C; Sterenborg, Henricus J C M

    2014-07-01

    High power femto-second (fs) laser pulses used for in-vivo nonlinear optical (NLO) imaging can form cyclobutane pyrimidine dimers (CPD) in DNA, which may lead to carcinogenesis via subsequent mutations. Since UV radiation from routine sun exposure is the primary source of CPD lesions, we evaluated the risk of CPD-related squamous cell carcinoma (SCC) in human skin due to NLO imaging relative to that from sun exposure. We developed a unique cancer risk model expanding previously published estimation of risk from exposure to continuous wave (CW) laser. This new model showed that the increase in CPD-related SCC in skin from NLO imaging is negligible above that due to regular sun exposure. PMID:23401419

  1. Nonlinear optical microscopy for immunoimaging: a custom optimized system of high-speed, large-area, multicolor imaging

    PubMed Central

    Li, Hui; Cui, Quan; Zhang, Zhihong; Luo, Qingming

    2015-01-01

    Background The nonlinear optical microscopy has become the current state-of-the-art for intravital imaging. Due to its advantages of high resolution, superior tissue penetration, lower photodamage and photobleaching, as well as intrinsic z-sectioning ability, this technology has been widely applied in immunoimaging for a decade. However, in terms of monitoring immune events in native physiological environment, the conventional nonlinear optical microscope system has to be optimized for live animal imaging. Generally speaking, three crucial capabilities are desired, including high-speed, large-area and multicolor imaging. Among numerous high-speed scanning mechanisms used in nonlinear optical imaging, polygon scanning is not only linearly but also dispersion-freely with high stability and tunable rotation speed, which can overcome disadvantages of multifocal scanning, resonant scanner and acousto-optical deflector (AOD). However, low frame rate, lacking large-area or multicolor imaging ability make current polygonbased nonlinear optical microscopes unable to meet the requirements of immune event monitoring. Methods We built up a polygon-based nonlinear optical microscope system which was custom optimized for immunoimaging with high-speed, large-are and multicolor imaging abilities. Results Firstly, we validated the imaging performance of the system by standard methods. Then, to demonstrate the ability to monitor immune events, migration of immunocytes observed by the system based on typical immunological models such as lymph node, footpad and dorsal skinfold chamber are shown. Finally, we take an outlook for the possible advance of related technologies such as sample stabilization and optical clearing for more stable and deeper intravital immunoimaging. Conclusions This study will be helpful for optimizing nonlinear optical microscope to obtain more comprehensive and accurate information of immune events. PMID:25694951

  2. Simultaneous quadruple modal nonlinear optical imaging for gastric diseases diagnosis and characterization

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Zheng, Wei; Lin, Jian; Huang, Zhiwei

    2015-03-01

    We report the development of a unique simultaneous quadruple-modal nonlinear optical microscopy (i.e., stimulated Raman scattering (SRS), second-harmonic generation (SHG), two-photon excitation fluorescence (TPEF), and third-harmonic generation (THG)) platform for characterization of the gastric diseases (i.e., gastritis, intestinal metaplasia (IM), intestinal type adenocarcinoma). SRS highlights the goblet cells found in IM. SHG images the distribution of collagen in lamina propria. Collagen is found to aggregate for intestinal type adenocarcinoma. TPEF reveals the cell morphology and can reflect the damage inside glands caused by the diseases. THG visualizes the nuclei with high spatial resolution, which facilitates the identification of neutrophils that are usually used as a feature of inflammation. This work shows that the co-registration of quadruple-modal images can be an effective means for diagnosis and characterization of gastric diseases at the cellular and molecular levels.

  3. Combination of widefield fluorescence imaging and nonlinear optical microscopy of oral epithelial neoplasia

    NASA Astrophysics Data System (ADS)

    Pal, Rahul; Edward, Kert; Brown, Tyra; Ma, Liang; Yang, Jinping; McCammon, Susan; Motamedi, Massoud; Vargas, Gracie

    2013-03-01

    Multiphoton Autofluorescence Microscopy (MPAM) and Second Harmonic Generation Microscopy (SHGM) have shown the potential for noninvasive assessment of oral precancers and cancers. We have explored a combination of these nonlinear optical microscopic imaging techniques with widefield fluorescence imaging to assess morphometry similar to that of pathologic evaluation as well as information from endogenous fluorophores, which are altered with neoplastic transformation. Widefield fluorescence revealed areas of interest corresponding to sites with precancers or early tumors, generally resulting in a decrease in green emission or increase in red emission. Subsequent microscopy revealed significant differences in morphology between normal, dysplastic/neoplastic mucosa for all layers. Combination of a widefield and a microscopic technique provides a novel approach for tissue morphometric analysis along with large area assessment of tissue autofluorescence properties.

  4. Multimodal Nonlinear Optical Microscopy

    PubMed Central

    Yue, Shuhua; Slipchenko, Mikhail N.; Cheng, Ji-Xin

    2013-01-01

    Because each nonlinear optical (NLO) imaging modality is sensitive to specific molecules or structures, multimodal NLO imaging capitalizes the potential of NLO microscopy for studies of complex biological tissues. The coupling of multiphoton fluorescence, second harmonic generation, and coherent anti-Stokes Raman scattering (CARS) has allowed investigation of a broad range of biological questions concerning lipid metabolism, cancer development, cardiovascular disease, and skin biology. Moreover, recent research shows the great potential of using CARS microscope as a platform to develop more advanced NLO modalities such as electronic-resonance-enhanced four-wave mixing, stimulated Raman scattering, and pump-probe microscopy. This article reviews the various approaches developed for realization of multimodal NLO imaging as well as developments of new NLO modalities on a CARS microscope. Applications to various aspects of biological and biomedical research are discussed. PMID:24353747

  5. Multimodal nonlinear optical imaging of obesity-induced liver steatosis and fibrosis

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Lu, Fake; Zheng, Wei; Tai, Dean C. S.; Yu, Hanry; Sheppard, Colin; Huang, Zhiwei

    2011-03-01

    Liver steatosis/fibrosis represents the major conditions and symptoms for many liver diseases. Nonlinear optical microscopy has emerged as a powerful tool for label-free tissue imaging with high sensitivity and chemical specificity for several typical biochemical compounds. Three nonlinear microscopy imaging modalities are implemented on the sectioned tissues from diseased livers induced by high fat diet (HFD). Coherent anti-Stokes Raman scattering (CARS) imaging visualizes and quantifies the lipid droplets accumulated in the liver, Second harmonic generation (SHG) is used to map the distribution of aggregated collagen fibers, and two-photon excitation fluorescence (TPEF) reveals the morphology of hepatic cells based on the autofluorescence signals from NADH and flavins within the hepatocytes. Our results demonstrate that obesity induces liver steatosis in the beginning stage, which may progress into liver fibrosis with high risk. There is a certain correlation between liver steatosis and fibrosis. This study may provide new insights into the understanding of the mechanisms of steatosis/fibrosis transformations at the cellular and molecular levels.

  6. Nonlinear optical techniques for imaging and manipulating the mouse central nervous system

    NASA Astrophysics Data System (ADS)

    Farrar, Matthew John

    The spinal cord of vertebrates serves as the conduit for somatosensory information and motor control, as well as being the locus of neural circuits that govern fast reflexes and patterned behaviors, such as walking in mammals or swimming in fish. Consequently, pathologies of the spinal cord -such as spinal cord injury (SCI)- lead to loss of motor control and sensory perception, with accompanying decline in life expectancy and quality of life. Despite the devastating effects of these diseases, few therapies exist to substantially ameliorate patient outcome. In part, studies of spinal cord pathology have been limited by the inability to perform in vivo imaging at the level of cellular processes. The focus of this thesis is to present the underlying theory for and demonstration of novel multi-photon microscopy (MPM) and optical manipulation techniques as they apply to studies the mouse central nervous system (CNS), with an emphasis on the spinal cord. The scientific findings which have resulted from the implementation of these techniques are also presented. In particular, we have demonstrated that third harmonic generation is a dye-free method of imaging CNS myelin, a fundamental constituent of the spinal cord that is difficult to label using exogenous dyes and/or transgenic constructs. Since gaining optical access to the spinal cord is a prerequisite for spinal cord imaging, we review our development of a novel spinal cord imaging chamber and surgical procedure which allowed us to image for multiple weeks following implantation without the need for repeated surgeries. We also have used MPM to characterize spinal venous blood flow before and after point occlusions. We review a novel nonlinear microscopy technique that may serve to show optical interfaces in three dimensions inside scattering tissue. Finally, we discuss a model and show results of optoporation, a means of transfecting cells with genetic constructs. Brief reviews of MPM and SCI are also presented.

  7. Nonlinear optical thin films

    NASA Technical Reports Server (NTRS)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  8. Label-free imaging of arterial tissues using photonic crystal fiber (PCF) based nonlinear optical microscopic system

    NASA Astrophysics Data System (ADS)

    Ko, Alex C. T.; Ridsdale, Andrew; Pegoraro, Adrian F.; Smith, Michael S. D.; Mostaço-Guidolin, Leila B.; Hewko, Mark D.; Kohlenberg, Elicia M.; Schattka, Bernie J.; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

    2009-02-01

    Nonlinear optical (NLO) microscopy provides a minimally invasive optical method for fast molecular imaging at subcellular resolution with 3D sectioning capability in thick, highly scattering biological tissues. In the current study, we demonstrate the imaging of arterial tissue using a nonlinear optical microscope based on photonic crystal fiber and a single femto-second oscillator operating at 800nm. This NLO microscope system is capable of simultaneous imaging extracellular elastin/collagen structures and lipid distribution within aortic tissue obtained from coronary atherosclerosis-prone WHHLMI rabbits (Watanabe heritable hyperlipidemic rabbit-myocardial infarction) Clear pathological differences in arterial lumen surface were observed between healthy arterial tissue and atherosclerotic lesions through NLO imaging.

  9. In Vivo Nonlinear Optical Imaging of Immune Responses: Tissue Injury and Infection

    PubMed Central

    Zeng, Yan; Yan, Bo; Xu, Jin; Sun, Qiqi; He, Sicong; Jiang, Jun; Wen, Zilong; Qu, Jianan Y.

    2014-01-01

    In this study, we demonstrate a noninvasive imaging approach based on multimodal nonlinear optical microscopy to in vivo image the responses of immune cells (neutrophils) to the tissue injury and bacterial infection in a zebrafish model. Specifically, the second harmonic generation from myosin thick filaments in sarcomere enabled a clear visualization of the muscle injury and infection. Two-photon excited fluorescence was used to track the behavior of the neutrophils that were transgenically labeled by red fluorescent protein. The corresponding reduced nicotinamide adenine dinucleotide (NADH) two-photon excited fluorescence images revealed a detailed morphological transformation process of individual neutrophils during muscle tissue injury and bacterial infection. The analysis of time-resolved NADH signals from the neutrophils provided important biological insights of the cellular energy metabolism during the immune responses. We found a significant increase of free/protein-bound NADH ratios in activated neutrophils in bacterial-infected tissue. In this study, we also discovered that, under 720 nm excitation, two wild-type strains (DH5α and BL21) of bacteria Escherichia coli emitted distinct endogenous fluorescence of double-peak at ∼450 and ∼520 nm, respectively. We demonstrated that the double-peak fluorescence signal could be used to differentiate the E. coli from surrounding tissues of dominant NADH signals, and to achieve label-free tracking of E. coli bacteria in vivo. PMID:25418312

  10. Time-gated imaging using nonlinear optical techniques applications to turbid materials

    NASA Astrophysics Data System (ADS)

    Reintjes, John F.; Duncan, Michael D.; Mahon, Rita; Tankersley, Lawrence L.; Bashkansky, Mark; Prewitt, Judith M. S.

    1993-09-01

    We describe the use of various nonlinear interactions based on stimulated Raman scattering for time gated imaging and their application to imaging through turbid media. Results are presented showing images obtained through solutions of non dairy creamer with attenuation of e-33 and 100 micrometers resolution, and through 6 mm of raw chicken meat, and 12 mm of human abdominal fat.

  11. Nonlinear optics at interfaces

    SciTech Connect

    Chen, C.K.

    1980-12-01

    Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory.

  12. Imaging of normal and pathologic joint synovium using nonlinear optical microscopy as a potential diagnostic tool

    NASA Astrophysics Data System (ADS)

    Tiwari, Nivedan; Chabra, Sanjay; Mehdi, Sheherbano; Sweet, Paula; Krasieva, Tatiana B.; Pool, Roy; Andrews, Brian; Peavy, George M.

    2010-09-01

    An estimated 1.3 million people in the United States suffer from rheumatoid arthritis (RA). RA causes profound changes in the synovial membrane of joints, and without early diagnosis and intervention, progresses to permanent alterations in joint structure and function. The purpose of this study is to determine if nonlinear optical microscopy (NLOM) can utilize the natural intrinsic fluorescence properties of tissue to generate images that would allow visualization of the structural and cellular composition of fresh, unfixed normal and pathologic synovial tissue. NLOM is performed on rabbit knee joint synovial samples using 730- and 800-nm excitation wavelengths. Less than 30 mW of excitation power delivered with a 40×, 0.8-NA water immersion objective is sufficient for the visualization of synovial structures to a maximum depth of 70 μm without tissue damage. NLOM imaging of normal and pathologic synovial tissue reveals the cellular structure, synoviocytes, adipocytes, collagen, vascular structures, and differential characteristics of inflammatory infiltrates without requiring tissue processing or staining. Further study to evaluate the ability of NLOM to assess the characteristics of pathologic synovial tissue and its potential role for the management of disease is warranted.

  13. A spectral approach for the quantitative description of cardiac collagen network from nonlinear optical imaging.

    PubMed

    Masè, Michela; Cristoforetti, Alessandro; Avogaro, Laura; Tessarolo, Francesco; Piccoli, Federico; Caola, Iole; Pederzolli, Carlo; Graffigna, Angelo; Ravelli, Flavia

    2015-08-01

    The assessment of collagen structure in cardiac pathology, such as atrial fibrillation (AF), is essential for a complete understanding of the disease. This paper introduces a novel methodology for the quantitative description of collagen network properties, based on the combination of nonlinear optical microscopy with a spectral approach of image processing and analysis. Second-harmonic generation (SHG) microscopy was applied to atrial tissue samples from cardiac surgery patients, providing label-free, selective visualization of the collagen structure. The spectral analysis framework, based on 2D-FFT, was applied to the SHG images, yielding a multiparametric description of collagen fiber orientation (angle and anisotropy indexes) and texture scale (dominant wavelength and peak dispersion indexes). The proof-of-concept application of the methodology showed the capability of our approach to detect and quantify differences in the structural properties of the collagen network in AF versus sinus rhythm patients. These results suggest the potential of our approach in the assessment of collagen properties in cardiac pathologies related to a fibrotic structural component. PMID:26737722

  14. Imaging of normal and pathologic joint synovium using nonlinear optical microscopy as a potential diagnostic tool

    PubMed Central

    Tiwari, Nivedan; Chabra, Sanjay; Mehdi, Sheherbano; Sweet, Paula; Krasieva, Tatiana B.; Pool, Roy; Andrews, Brian; Peavy, George M.

    2010-01-01

    An estimated 1.3 million people in the United States suffer from rheumatoid arthritis (RA). RA causes profound changes in the synovial membrane of joints, and without early diagnosis and intervention, progresses to permanent alterations in joint structure and function. The purpose of this study is to determine if nonlinear optical microscopy (NLOM) can utilize the natural intrinsic fluorescence properties of tissue to generate images that would allow visualization of the structural and cellular composition of fresh, unfixed normal and pathologic synovial tissue. NLOM is performed on rabbit knee joint synovial samples using 730- and 800-nm excitation wavelengths. Less than 30 mW of excitation power delivered with a 40×, 0.8-NA water immersion objective is sufficient for the visualization of synovial structures to a maximum depth of 70 μm without tissue damage. NLOM imaging of normal and pathologic synovial tissue reveals the cellular structure, synoviocytes, adipocytes, collagen, vascular structures, and differential characteristics of inflammatory infiltrates without requiring tissue processing or staining. Further study to evaluate the ability of NLOM to assess the characteristics of pathologic synovial tissue and its potential role for the management of disease is warranted. PMID:21054095

  15. Imaging nanomaterials in vitro and in vivo by exploring their intrinsic nonlinear optical signals

    NASA Astrophysics Data System (ADS)

    Tong, Ling

    The extension of nanotechnology to biomedical system creates a new and fast developing field, nanomedicine. A wide range of nanoparticles has been developed as imaging agents or drug carriers. However, the translation of nanomedicines to a clinical setting has been slowed down due to a limited fundamental understanding of the nano-bio interaction. My thesis work describes the efforts in imaging the behavior of nanomaterials in live cells and animals by exploring the nonlinear optical properties. The first part of my thesis focuses on study of metallic and semiconducting nanoparticles in biological environment using their nonlinear optical signals. In chapter 2, systemic circulation of PEGylated gold nanorods (GNRs) is visualized by intravital two-photon luminescence (TPL) imaging. A biphasic clearance is demonstrated with branched PEG showing longer circulation. Following clearance, cellular biodistribution of GNRs in organs is mapped by TPL imaging. GNRs accumulate in macrophages in liver and spleen (Langmuir, 2009, 25, 12454-12459). In chapter 3, a bright three-photon luminescence is discovered from Au-Ag alloyed nanostructure by excitation with a femtosecond laser at 1290 nm, which enables bio-imaging with negligible photothermal toxicity and tissue autofluorescence (Angew Chemie, 2010, 49, 3485-3488, inside cover story). In chapter 4, a new contrast is invented for label-free, real-time imaging of single-walled carbon nanotubes (SWNTs) by pump-probe microscopy. At pump/probe wavelength of 707 and 885 nm, semiconducting and metallic SWNTs (S-SWNTs and M-SWNTs) exhibit intense stimulated emission and absorption signals, which allow us to monitor the intracellular trafficking, distribution in tissues, and systemic circulation in vivo with single-nanotube sensitivity and sub-micron resolution. The second part presents label-free imaging of nanomedicines in live cells by coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microscopy

  16. Solitons in nonlinear optics

    SciTech Connect

    Maimistov, Andrei I

    2010-11-13

    The classic examples of optical phenomena resulting in the appearance of solitons are self-focusing, self-induced transparency, and parametric three-wave interaction. To date, the list of the fields of nonlinear optics and models where solitons play an important role has significantly expanded. Now long-lived or stable solitary waves are called solitons, including, for example, dissipative, gap, parametric, and topological solitons. This review considers nonlinear optics models giving rise to the appearance of solitons in a narrow sense: solitary waves corresponding to the solutions of completely integrable systems of equations basic for the models being discussed. (review)

  17. Near Infrared (NIR) Imaging Techniques Using Lasers and Nonlinear Crystal Optical Parametric Oscillator/Amplifier (OPO/OPA) Imaging and Transferred Electron (TE) Photocathode Image Intensifiers

    SciTech Connect

    YATES,GEORGE J.; MCDONALD,THOMAS E. JR.; BLISS,DAVID E.; CAMERON,STEWART M.; GREIVES,KENNETH H.; ZUTAVERN,FRED J.

    2000-12-20

    Laboratory experiments utilizing different near-infrared (NIR) sensitive imaging techniques for LADAR range gated imaging at eye-safe wavelengths are presented. An OPO/OPA configuration incorporating a nonlinear crystal for wavelength conversion of 1.56 micron probe or broadcast laser light to 807 nm light by utilizing a second pump laser at 532 nm for gating and gain, was evaluated for sensitivity, resolution, and general image quality. These data are presented with similar test results obtained from an image intensifier based upon a transferred electron (TE) photocathode with high quantum efficiency (QE) in the 1-2 micron range, with a P-20 phosphor output screen. Data presented include range-gated imaging performance in a cloud chamber with varying optical attenuation of laser reflectance images.

  18. Epi-detected quadruple-modal nonlinear optical microscopy for label-free imaging of the tooth

    SciTech Connect

    Wang, Zi; Zheng, Wei; Huang, Zhiwei; Stephen Hsu, Chin-Ying

    2015-01-19

    We present an epi-detected quadruple-modal nonlinear optical microscopic imaging technique (i.e., coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), third-harmonic generation (THG), and two-photon excited fluorescence (TPEF)) based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of the tooth. We demonstrate that high contrast ps-CARS images covering both the fingerprint (500–1800 cm{sup −1}) and high-wavenumber (2500–3800 cm{sup −1}) regions can be acquired to uncover the distributions of mineral and organic biomaterials in the tooth, while high quality TPEF, SHG, and THG images of the tooth can also be acquired under ps laser excitation without damaging the samples. The quadruple-modal nonlinear microscopic images (CARS/SHG/THG/TPEF) acquired provide better understanding of morphological structures and biochemical/biomolecular distributions in the dentin, enamel, and the dentin-enamel junction of the tooth without labeling, facilitating optical diagnosis and characterization of the tooth in dentistry.

  19. Epi-detected quadruple-modal nonlinear optical microscopy for label-free imaging of the tooth

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Zheng, Wei; Stephen Hsu, Chin-Ying; Huang, Zhiwei

    2015-01-01

    We present an epi-detected quadruple-modal nonlinear optical microscopic imaging technique (i.e., coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), third-harmonic generation (THG), and two-photon excited fluorescence (TPEF)) based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of the tooth. We demonstrate that high contrast ps-CARS images covering both the fingerprint (500-1800 cm-1) and high-wavenumber (2500-3800 cm-1) regions can be acquired to uncover the distributions of mineral and organic biomaterials in the tooth, while high quality TPEF, SHG, and THG images of the tooth can also be acquired under ps laser excitation without damaging the samples. The quadruple-modal nonlinear microscopic images (CARS/SHG/THG/TPEF) acquired provide better understanding of morphological structures and biochemical/biomolecular distributions in the dentin, enamel, and the dentin-enamel junction of the tooth without labeling, facilitating optical diagnosis and characterization of the tooth in dentistry.

  20. In-situ imaging of reacting single-particle zeolites by non-linear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wrzesinski, Paul J.; Slipchenko, Mikhail N.; Zaman, Taslima A.; Rioux, Robert M.; Gord, James R.; Roy, Sukesh

    2015-03-01

    Zeolite catalysis has been exploited by the petrochemical industry since the 1940's for catalytic cracking reactions of long chain hydrocarbons. The selectivity of zeolites strongly depends on a pore size, which is controlled by the chosen structure-directing agent (SDA) and by the SDA decomposition/removal process. Although zeolites are composed of micron-sized crystals, studies of zeolite materials typically focus on bulk (i.e., ensemble) measurements to elucidate structure-function information or to optimize catalysts and/or process parameters. To examine these phenomena on the microscale, non-linear optical microscopy is used to provide real-time imaging of chemical reactions in zeolites at temperatures exceeding 400°C. The template decomposition mechanism is studied, as elucidation of the mechanism is critical to understanding the relationship between the decomposition chemistry and the nanoscale features of the zeolite (topology, Si/Al ratio, added dopants). Forward stimulated Raman scattering (SRS), forward coherent anti-Stokes Raman scattering (CARS) and epi two-photon fluorescence (TPF) modalities are acquired simultaneously providing video-rate structural and chemical information. A high-temperature cell with gas inlet system is used for the study of reactions under various temperatures and gas environments. Examining the decomposition process with single-particle resolution enables access to ensemble-level and spatially-resolved behavior. Parallel experiments on bulk zeolite powders are conducted to enable comparison of ensemble and single-particle behavior during template decomposition. Our multi-technique approach has high potential for gaining insight into the link between nanoscale structure and catalytic activity and selectivity of zeolitic materials.

  1. Nonlinear optical Galton board

    SciTech Connect

    Navarrete-Benlloch, C.; Perez, A.; Roldan, Eugenio

    2007-06-15

    We generalize the concept of optical Galton board (OGB), first proposed by Bouwmeester et al. [Phys. Rev. A 61, 013410 (2000)], by introducing the possibility of nonlinear self-phase modulation on the wave function during the walker evolution. If the original Galton board illustrates classical diffusion, the OGB, which can be understood as a grid of Landau-Zener crossings, illustrates the influence of interference on diffusion, and is closely connected with the quantum walk. Our nonlinear generalization of the OGB shows new phenomena, the most striking of which is the formation of nondispersive pulses in the field distribution (solitonlike structures). These exhibit a variety of dynamical behaviors, including ballistic motion, dynamical localization, nonelastic collisions, and chaotic behavior, in the sense that the dynamics is very sensitive to the nonlinearity strength.

  2. Nonlinear optical protection against frequency agile lasers

    SciTech Connect

    McDowell, V.P.

    1988-08-04

    An eye-protection or equipment-filter device for protection from laser energy is disclosed. The device may be in the form of a telescope, binoculars, goggles, constructed as part of equipment such as image intensifiers or range designators. Optical elements focus the waist of the beam within a nonlinear frequency-doubling crystal or nonlinear optical element or fiber. The nonlinear elements produce a harmonic outside the visible spectrum in the case of crystals, or absorb the laser energy in the case of nonlinear fibers. Embodiments include protectors for the human eye as well as filters for sensitive machinery such as TV cameras, FLIR systems or other imaging equipment.

  3. Multipurpose nonlinear optical imaging system for in vivo and ex vivo multimodal histology

    PubMed Central

    Weinigel, Martin; Breunig, Hans Georg; Uchugonova, Aisada; König, Karsten

    2015-01-01

    Abstract. We report on a flexible multipurpose nonlinear microscopic imaging system based on a femtosecond excitation source and a photonic crystal fiber with multiple miniaturized time-correlated single-photon counting detectors. The system provides the simultaneous acquisition of e.g., two-photon autofluorescence, second-harmonic generation, and coherent anti-Stokes Raman scattering images. Its flexible scan head permits ex vivo biological imaging with subcellular resolution such as rapid biopsy examination during surgery as well as imaging on small as well as large animals. Above all, such an arrangement perfectly matches the needs for the clinical investigation of human skin in vivo where knowledge about the distribution of endogenous fluorophores, second-harmonic generation–active collagen as well as nonfluorescent lipids is of high interest. PMID:26158089

  4. Focal-Plane Imaging of Crossed Beams in Nonlinear Optics Experiments

    NASA Technical Reports Server (NTRS)

    Bivolaru, Daniel; Herring, G. C.

    2007-01-01

    An application of focal-plane imaging that can be used as a real time diagnostic of beam crossing in various optical techniques is reported. We discuss two specific versions and demonstrate the capability of maximizing system performance with an example in a combined dual-pump coherent anti-Stokes Raman scattering interferometric Rayleigh scattering experiment (CARS-IRS). We find that this imaging diagnostic significantly reduces beam alignment time and loss of CARS-IRS signals due to inadvertent misalignments.

  5. Nonlinear optical interference of two successive coherent anti-Stokes Raman scattering signals for biological imaging applications.

    PubMed

    Lee, Eun Seong; Lee, Jae Yong; Yoo, Yong Shim

    2007-01-01

    The nonlinear optical interference of two successively generated coherent anti-Stokes Raman scattering (CARS) signals from two different samples placed in series is demonstrated for the imaging performance, in which a collinear phase matching geometry is used. The relative phase of two CARS signals is controlled by a phase-shifting unit made of dispersive glass materials of which the thickness can be precisely varied. The clear interference fringes are observed as the thickness of the phase-shifting unit changes. The interference effect is then utilized to achieve a better quality CARS image of a biological tissue taken from a mouse skin. Placing the tissue in the second sample position and performing raster scans of the laser beams on it, we can acquire a CARS image of higher contrast compared to the normal image obtained without interferometric implementation. PMID:17477725

  6. Frequency domain nonlinear optics

    NASA Astrophysics Data System (ADS)

    Legare, Francois

    2016-05-01

    The universal dilemma of gain narrowing occurring in fs amplifiers prevents ultra-high power lasers from delivering few-cycle pulses. This problem is overcome by a new amplification concept: Frequency domain Optical Parametric Amplification - FOPA. It enables simultaneous up-scaling of peak power and amplified spectral bandwidth and can be performed at any wavelength range of conventional amplification schemes, however, with the capability to amplify single cycles of light. The key idea for amplification of octave-spanning spectra without loss of spectral bandwidth is to amplify the broad spectrum ``slice by slice'' in the frequency domain, i.e. in the Fourier plane of a 4f-setup. The striking advantages of this scheme, are its capability to amplify (more than) one octave of bandwidth without shorting the corresponding pulse duration. This is because ultrabroadband phase matching is not defined by the properties of the nonlinear crystal employed but the number of crystals employed. In the same manner, to increase the output energy one simply has to increase the spectral extension in the Fourier plane and to add one more crystal. Thus, increasing pulse energy and shortening its duration accompany each other. A proof of principle experiment was carried out at ALLS on the sub-two cycle IR beam line and yielded record breaking performance in the field of few-cycle IR lasers. 100 μJ two-cycle pulses from a hollow core fibre compression setup were amplified to 1.43mJ without distorting spatial or temporal properties. Pulse duration at the input of FOPA and after FOPA remains the same. Recently, we have started upgrading this system to be pumped by 250 mJ to reach 40 mJ two-cycle IR few-cycle pulses and latest results will be presented at the conference. Furthermore, the extension of the concept of FOPA to other nonlinear optical processes will be discussed. Frequency domain nonlinear optics.

  7. Nonlinear optical whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor)

    2005-01-01

    Whispering gallery mode (WGM) optical resonators comprising nonlinear optical materials, where the nonlinear optical material of a WGM resonator includes a plurality of sectors within the optical resonator and nonlinear coefficients of two adjacent sectors are oppositely poled.

  8. Assembly and characterization of a nonlinear optical microscopy for in vivo and ex vivo tissue imaging

    NASA Astrophysics Data System (ADS)

    Pratavieira, S.; Buzzá, H. H.; Jorge, A. E.; Grecco, C.; Pires, L.; Cosci, A.; Bagnato, V. S.; Kurachi, C.

    2014-02-01

    The purpose of this study is the assembly and characterization of a custom-made non-linear microscope. The microscope allows the adjustment for in vitro, in vivo and ex vivo imaging of biological samples. Two galvanometer mirrors conjugated by two spherical mirrors are used for the lateral scan and for the axial scan a piezoeletric stage is utilized. The excitation is done using a tunable femtosecond Ti: Sapphire laser. The light is focused in tissue by an objective lens 20X, water immersion, numerical aperture of 1.0, and working distance of 2.0 mm. The detection system is composed by a cut off filter that eliminates laser light back reflections and diverse dichroic filters can be chosen to split the emitted signal for the two photomultiplier detector. The calibration and resolution of the microscope was done using a stage micrometer with 10 μm divisions and fluorescent particle slide, respectively. Fluorescence and second harmonic generation images were performed using epithelial and hepatic tissue, the images have a sub-cellular spatial resolution. Further characterization and differentiation of tissue layers can be obtained by performing axial scanning. By means of the microscope it is possible to have a three dimensional reconstruction of tissues with sub-cellular resolution.

  9. Attosecond Nonlinear Optics

    SciTech Connect

    Midorikawa, Katsumi

    2010-10-08

    We report nonlinear multiphoton processes in atoms and molecules by intense high harmonics and their applications to attosecond pulse characterization. Phase matched high harmonics by a loosely focusing geometry produce highly focusable intensity with fully spatiotemporal coherence, which is sufficient to induce nonlinear optical phenomena in the extreme ultraviolet and soft x-ray (XUV) region. With this XUV coherent light source, two-photon double ionization in He is demonstrated with 42-eV high harmonic photons. On the other hand, when intense high harmonics around 20 eV is subjected to N{sub 2} molecules, occurrence of Coulomb explosion following to two-photon double ionization is observed in attosecond temporal precision. Taking advantage of larger cross section of two-photon ionization in molecules, we successfully perform the interferometric autocorrelation of an attosecond pulse train with the ion signals produced by Coulomb explosion of nitrogen molecules. The result reveals the phase relation between attosecond pulses in the train.

  10. Mathematical opportunities in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Optics is described in this survey as being so scientifically fertile and technologically promising that it is destined to be one of the most important areas of science for the next quarter century. The study of nonlinear optics is fascinating both because of the enormous technological dividends that are likely and because of the intrinsic scientific interest. This survey notes that on the technological side nonlinear optics is likely to revolutionize future telecommunications and computer technologies, while on the mathematical side it is an ideal subject for the applied mathematician, who is particularly well positioned to make major contributions. Also, optics displays the full spectrum of behavior associated with nonlinear equations. There are several new concepts of nonlinear science, including the soliton and the strange attractor, which are very important in nonlinear optics and which require some depth of mathematical knowledge to understand.

  11. Chirality in nonlinear optics.

    PubMed

    Haupert, Levi M; Simpson, Garth J

    2009-01-01

    The past decade has witnessed the emergence of new measurement approaches and applications for chiral thin films and materials enabled by the observations of the high sensitivity of second-order nonlinear optical measurements to chirality. In thin films, the chiral response to second harmonic generation and sum frequency generation (SFG) from a single molecular monolayer is often comparable with the achiral response. The chiral specificity also allows for symmetry-allowed SFG in isotropic chiral media, confirming predictions made approximately 50 years ago. With these experimental demonstrations in hand, an important challenge is the construction of intuitive predictive models that allow the measured chiral response to be meaningfully related back to molecular and macromolecular structure. This review defines and considers three distinct mechanisms for chiral effects in uniaxially oriented assemblies: orientational chirality, intrinsic chirality, and isotropic chirality. The role of each is discussed in experimental and computational studies of bacteriorhodopsin films, binaphthol, and collagen. Collectively, these three model systems support a remarkably simple framework for quantitatively recovering the measured chiral-specific activity. PMID:19046125

  12. Chirality in Nonlinear Optics

    NASA Astrophysics Data System (ADS)

    Haupert, Levi M.; Simpson, Garth J.

    2009-05-01

    The past decade has witnessed the emergence of new measurement approaches and applications for chiral thin films and materials enabled by the observations of the high sensitivity of second-order nonlinear optical measurements to chirality. In thin films, the chiral response to second harmonic generation and sum frequency generation (SFG) from a single molecular monolayer is often comparable with the achiral response. The chiral specificity also allows for symmetry-allowed SFG in isotropic chiral media, confirming predictions made ˜50 years ago. With these experimental demonstrations in hand, an important challenge is the construction of intuitive predictive models that allow the measured chiral response to be meaningfully related back to molecular and macromolecular structure. This review defines and considers three distinct mechanisms for chiral effects in uniaxially oriented assemblies: orientational chirality, intrinsic chirality, and isotropic chirality. The role of each is discussed in experimental and computational studies of bacteriorhodopsin films, binaphthol, and collagen. Collectively, these three model systems support a remarkably simple framework for quantitatively recovering the measured chiral-specific activity.

  13. Integrated nonlinear optical imaging microscope for on-axis crystal detection and centering at a synchrotron beamline.

    PubMed

    Madden, Jeremy T; Toth, Scott J; Dettmar, Christopher M; Newman, Justin A; Oglesbee, Robert A; Hedderich, Hartmut G; Everly, R Michael; Becker, Michael; Ronau, Judith A; Buchanan, Susan K; Cherezov, Vadim; Morrow, Marie E; Xu, Shenglan; Ferguson, Dale; Makarov, Oleg; Das, Chittaranjan; Fischetti, Robert; Simpson, Garth J

    2013-07-01

    Nonlinear optical (NLO) instrumentation has been integrated with synchrotron X-ray diffraction (XRD) for combined single-platform analysis, initially targeting applications for automated crystal centering. Second-harmonic-generation microscopy and two-photon-excited ultraviolet fluorescence microscopy were evaluated for crystal detection and assessed by X-ray raster scanning. Two optical designs were constructed and characterized; one positioned downstream of the sample and one integrated into the upstream optical path of the diffractometer. Both instruments enabled protein crystal identification with integration times between 80 and 150 µs per pixel, representing a ∼10(3)-10(4)-fold reduction in the per-pixel exposure time relative to X-ray raster scanning. Quantitative centering and analysis of phenylalanine hydroxylase from Chromobacterium violaceum cPAH, Trichinella spiralis deubiquitinating enzyme TsUCH37, human κ-opioid receptor complex kOR-T4L produced in lipidic cubic phase (LCP), intimin prepared in LCP, and α-cellulose samples were performed by collecting multiple NLO images. The crystalline samples were characterized by single-crystal diffraction patterns, while α-cellulose was characterized by fiber diffraction. Good agreement was observed between the sample positions identified by NLO and XRD raster measurements for all samples studied. PMID:23765294

  14. Integrated nonlinear optical imaging microscope for on-axis crystal detection and centering at a synchrotron beamline

    PubMed Central

    Madden, Jeremy T.; Toth, Scott J.; Dettmar, Christopher M.; Newman, Justin A.; Oglesbee, Robert A.; Hedderich, Hartmut G.; Everly, R. Michael; Becker, Michael; Ronau, Judith A.; Buchanan, Susan K.; Cherezov, Vadim; Morrow, Marie E.; Xu, Shenglan; Ferguson, Dale; Makarov, Oleg; Das, Chittaranjan; Fischetti, Robert; Simpson, Garth J.

    2013-01-01

    Nonlinear optical (NLO) instrumentation has been integrated with synchrotron X-ray diffraction (XRD) for combined single-platform analysis, initially targeting applications for automated crystal centering. Second-harmonic-generation microscopy and two-photon-excited ultraviolet fluorescence microscopy were evaluated for crystal detection and assessed by X-ray raster scanning. Two optical designs were constructed and characterized; one positioned downstream of the sample and one integrated into the upstream optical path of the diffractometer. Both instruments enabled protein crystal identification with integration times between 80 and 150 µs per pixel, representing a ∼103–104-fold reduction in the per-pixel exposure time relative to X-ray raster scanning. Quantitative centering and analysis of phenylalanine hydroxylase from Chromobacterium violaceum cPAH, Trichinella spiralis deubiquitinating enzyme TsUCH37, human κ-opioid receptor complex kOR-T4L produced in lipidic cubic phase (LCP), intimin prepared in LCP, and α-cellulose samples were performed by collecting multiple NLO images. The crystalline samples were characterized by single-crystal diffraction patterns, while α-cellulose was characterized by fiber diffraction. Good agreement was observed between the sample positions identified by NLO and XRD raster measurements for all samples studied. PMID:23765294

  15. Nonlinear phased array imaging

    NASA Astrophysics Data System (ADS)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  16. Nonlinear Optical Imaging for Sensitive Detection of Crystals in Bulk Amorphous Powders

    PubMed Central

    KESTUR, UMESH S.; WANAPUN, DUANGPORN; TOTH, SCOTT J.; WEGIEL, LINDSAY A.; SIMPSON, GARTH J.; TAYLOR, LYNNE S.

    2013-01-01

    The primary aim of this study was to evaluate the utility of second-order nonlinear imaging of chiral crystals (SONICC) to quantify crystallinity in drug–polymer blends, including solid dispersions. Second harmonic generation (SHG) can potentially exhibit scaling with crystallinity between linear and quadratic depending on the nature of the source, and thus, it is important to determine the response of pharmaceutical powders. Physical mixtures containing different proportions of crystalline naproxen and hydroxyl propyl methyl cellulose acetate succinate (HPMCAS) were prepared by blending and a dispersion was produced by solvent evaporation. A custom-built SONICC instrument was used to characterize the SHG intensity as a function of the crystalline drug fraction in the various samples. Powder X-ray diffraction (PXRD) and Raman spectroscopy were used as complementary methods known to exhibit linear scaling. SONICC was able to detect crystalline drug even in the presence of 99.9 wt % HPMCAS in the binary mixtures. The calibration curve revealed a linear dynamic range with a R2 value of 0.99 spanning the range from 0.1 to 100 wt % naproxen with a root mean square error of prediction of 2.7%. Using the calibration curve, the errors in the validation samples were in the range of 5%–10%. Analysis of a 75 wt % HPMCAS–naproxen solid dispersion with SONICC revealed the presence of crystallites at an earlier time point than could be detected with PXRD and Raman spectroscopy. In addition, results from the crystallization kinetics experiment using SONICC were in good agreement with Raman spectroscopy and PXRD. In conclusion, SONICC has been found to be a sensitive technique for detecting low levels (0.1% or lower) of crystallinity, even in the presence of large quantities of a polymer. PMID:22847843

  17. Towards multimodal nonlinear optical tomography - experimental methodology

    NASA Astrophysics Data System (ADS)

    Vogler, N.; Medyukhina, A.; Latka, I.; Kemper, S.; Böhm, M.; Dietzek, B.; Popp, J.

    2011-08-01

    All-optical microspectroscopic and tomographic tools reveal great potential for clinical dermatologic diagnostics, i.e., investigation of human skin and skin diseases. While optical-coherence tomography has been complemented by two-photon fluorescence tomography and second-harmonic generation tomography, a joint study of various nonlinear optical microspectroscopies, i.e., application of the recently developed multimodal imaging approach, to sizable human-tissue samples has not been evaluated up to now. Here, we present such multimodal approach combining different nonlinear optical contrast mechanisms for imaging, namely two-photon excited fluorescence (TPF), second-harmonic generation (SHG), and coherent anti-Stokes Raman scattering (CARS) into a joint microscopic experiment. We show the potential of imaging large skin areas and discuss the information obtained in a case study comparing normal skin and keloid tissue.

  18. Mathematical opportunities in nonlinear optics

    NASA Astrophysics Data System (ADS)

    The Board on Mathematical Sciences takes as one of its functions that of identifying areas of important or emerging research activity and focusing attention on them. The Board seeks to stimulate cross-disciplinary research between mathematical sciences and disciplines. This survey notes that on the technological side nonlinear optics is likely to revolutionize future telecommunications and computer technologies, while on the mathematical side it is an ideal subject for the applied mathematician, who is particularly well positioned to make major contributions. Topics covered include wave propagation and the nonlinear Schrodinger equation; soliton propagation in the optical fibers; nonlinear waveguides; four-wave mixing, phase conjunction, and beam cleanup; lasers; optical bistability, logic elements, and information storing patterns; and spatiotemporal complexity and turbulence in nonlinear optics.

  19. Optical characters of prostate using nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Shulian; Li, Hui; Zhang, Xiaoman; Wang, Yunxia; Peng, Dongqing

    2012-12-01

    The incidence rate of the prostatic hyperplasia is increasing in near decade, early detection is important for preventing the prostatic cancer (PCa). In this study, the images of prostate and cavernous nerves were carried out using intrinsic fluorescence and scattering properties of the tissues without any exogenous dye or contrast agent based on nonlinear optical microscope. The texture feature and optical property of the interfibrillar substance in prostate tissue were extracted and analyzed for charactering the prostate structure. It will be the feature parameter to differentiate the normal, the inflammation or cancer of prostate tissue in clinical with the application of miniature endoscope nonlinear optical microscope in vivo.

  20. Nonlinear optical properties and nonlinear optical probes of organic materials

    NASA Astrophysics Data System (ADS)

    Meredith, Gerald R.

    1992-02-01

    Nonlinear optical processes and electro-optical effects are expected to have increasing importance as the information age matures and photonics augment electronics in various high density and high bandwidth technologies. Whereas for electronics the emphasis is in construction of smaller device structures from a few parent materials, for organic materials the direction of materials research has been reversed. For some time it's been known that some molecular structures engender exceptionally large molecular nonlinear-polarization responses. If such molecules could be assembled in convenient, versatile, and reliable ways, the resulting materials would be very useful or even enabling in various photonics applications. The mature science and art of chemistry allows very good control over molecular composition and structure and, as will be illustrated in this talk, our knowledge of hyperpolarizability structure- property relationships is advancing rapidly. However, the science of fabrication and arrangement in molecular ensembles and polymers is rather primitive. Thus the goal to develop the appropriately structured materials for utilization in nonlinear and electro-optics has fostered the widespread use of nonlinear optical processes to probe the nature of supramolecular order and assembly. Examples of intrinsic and artificially assembled structures of crystals, molecular aggregates, polymeric orientational electrets and molecular mono- and multi-layer thin films will be shown. Nonlinear optical processes, primarily second-harmonic generation, provide unique probes of these structures, their assembly, and evolution.

  1. Biomolecular Imaging with Coherent Nonlinear Vibrational Microscopy

    PubMed Central

    Chung, Chao-Yu; Boik, John; Potma, Eric O.

    2014-01-01

    Optical imaging with spectroscopic vibrational contrast is a label-free solution for visualizing, identifying, and quantifying a wide range of biomolecular compounds in biological materials. Both linear and nonlinear vibrational microscopy techniques derive their imaging contrast from infrared active or Raman allowed molecular transitions, which provide a rich palette for interrogating chemical and structural details of the sample. Yet nonlinear optical methods, which include both second-order sum-frequency generation (SFG) and third-order coherent Raman scattering (CRS) techniques, offer several improved imaging capabilities over their linear precursors. Nonlinear vibrational microscopy features unprecedented vibrational imaging speeds, provides strategies for higher spatial resolution, and gives access to additional molecular parameters. These advances have turned vibrational microscopy into a premier tool for chemically dissecting live cells and tissues. This review discusses the molecular contrast of SFG and CRS microscopy and highlights several of the advanced imaging capabilities that have impacted biological and biomedical research. PMID:23245525

  2. Optical Image Subtraction

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Chao, Tien-Hsin

    1988-01-01

    Report reviews optical image subtraction techniques developed during years 1975 through 1985. Useful in such disciplines as studies of earth resources, meteorology, automatic surveillance, pattern recognition, studies of urban growth, and compression of bandwidth in communication systems. Describes following real-time techniques: source encoding, polarization modulation, pseudocolor image-difference detection, holographic-shear-lens technique, and nonlinear electro-optics. Reported non-real-time image-subtraction techniques are following, all of which involve intensity subtraction: speckle-diffuser encoding, speckle-pattern encoding, halftone-screen encoding,and polarization-shifted carrier encoding. Offers an attractive alternative to digital electronic image subtraction, is faster and treats all parts of images simultaneously.

  3. Surface nonlinear optics

    SciTech Connect

    Shen, Y.R.; Chen, C.K.; de Castro, A.R.B.

    1980-01-01

    Surface electromagnetic waves are waves propagating along the interface of two media. Their existence was predicted by Sommerfield in 1909. In recent years, interesting applications have been found in the study of overlayers and molecular adsorption on surfaces, in probing of phase transitions, and in measurements of refractive indices. In the laboratory, the nonlinear interaction of surface electromagnetic waves were studied. The preliminary results of this recent venture in this area are presented.

  4. Diphenylpolyynes For Nonlinear Optical Devices

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E.; Perry, Joseph W.; Coulter, Daniel R.

    1989-01-01

    Several diphenylpolyyne compounds found to exhibit second-order nonlinear electric susceptibilities and chemical structures conducive to orientation in appropriate chemical environments. These features make new materials suitable for use in optical devices. Diphenylacetylene links give molecules rodlike characteristics making them amenable to orientation by suspension in liquid crystals. New molecules also have inherent liquid-crystalline properties enabling them to be oriented directly.

  5. Nonlinear optical properties of bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Hendrickx, Eric; Verbiest, Thierry; Clays, Koen J.; Persoons, Andre P.

    1993-04-01

    In this paper we show the applicability of Hyper-Rayleigh scattering to obtain hyperpolarizabilities of ionic and biochemical compounds. It was found that dark-adapted bacteriorhodopsin and its isolated chromophore have considerable second order nonlinear optical properties. Information obtained from depolarization studies of the scattered light is discussed.

  6. Nonlinear optics in relativistic plasmas.

    PubMed

    Umstadter, D; Chen, S Y; Wagner, R; Maksimchuk, A; Sarkisov, G

    1998-03-30

    We review our recent work on the various nonlinear optical processes that occur as an intense laser propagates through a relativistic plasma. These include the experimental observations of electron acceleration driven by laser-wakefield generation, relativistic self-focusing, waveguide formation and laser self-channeling. PMID:19377614

  7. Basic considerations on surface optical nonlinearities

    SciTech Connect

    Guyot-Sionnest, P.; Chen, W.; Shen, Y.R.

    1986-01-01

    The origins of the surface nonlinearity in surface second harmonic generation are discussed. It is shown that this second-order nonlinear optical process is characterized by a surface nonlinear susceptibility tensor containing both local and nonlocal contributions.

  8. Unsymmetrical squaraines for nonlinear optical materials

    NASA Technical Reports Server (NTRS)

    Marder, Seth R. (Inventor); Chen, Chin-Ti (Inventor); Cheng, Lap-Tak (Inventor)

    1996-01-01

    Compositions for use in non-linear optical devices. The compositions have first molecular electronic hyperpolarizability (.beta.) either positive or negative in sign and therefore display second order non-linear optical properties when incorporated into non-linear optical devices.

  9. Describing functions for nonlinear optical systems.

    PubMed

    Ghosh, A K

    1997-10-10

    The concept of describing functions is useful for analyzing and designing nonlinear systems. A proposal for using the idea of describing functions for studying the behavior of a nonlinear optical processing system is given. The describing function can be used in the same way that a coherent transfer function or optical transfer function is used to characterize linear, shift-invariant optical processors. Two coherent optical systems for measuring the magnitude of the describing function of nonlinear optical processors are suggested. PMID:18264243

  10. Films Containing Optically Nonlinear Diacetylene Monomer

    NASA Technical Reports Server (NTRS)

    Paley, Mark S.; Mcmanus, Samuel P.; Frazier, Donald O.

    1993-01-01

    Solid films exhibiting nonlinear optical properties prepared as mixtures of poly(methyl methacrylate) with various amounts of diacetylene monomer called "compound 1" in article, "Synthesizing Diacetylenes With Nonlinear Optical Properties" (MFS-26186). Useful as phase-conjugate mirrors in laser-beam communications and as optical switches in optical computers. This particular diacetylene monomer exhibits strong third-order nonlinear optical properties, both in pure form and in solution.

  11. Single-cycle nonlinear optics

    SciTech Connect

    Max-Planck-Institut fur Quantenoptik; Goulielmakis, E.; Schultze, M.; Hofstetter, M.; Yakovlev, V. S.; Gagnon, J.; Uiberacker, M.; Aquila, A. L.; gullikson, E. M.; attwood, D. T.; Kienberger, R.; Krausz, F.; Kleineberg, U.

    2008-11-05

    Nonlinear optics plays a central role in the advancement of optical science and laser-based technologies. We report on the confinement of the nonlinear interaction of light with matter to a single wave cycle and demonstrate its utility for time-resolved and strong-field science. The electric field of 3.3-femtosecond, 0.72-micron laser pulses with a controlled and measured waveform ionizes atoms near the crests of the central wave cycle, with ionization being virtually switched off outside this interval. Isolated sub-100-attosecond pulses of extreme ultraviolet light (photon energy {approx} 80 electron volts), containing {approx} 0.5 nanojoule of energy, emerge from the interaction with a conversion efficiency of {approx} 10{sup -6}. These tools enable the study of the precision control of electron motion with light fields and electron-electron interactions with a resolution approaching the atomic unit of time ({approx} 24 attoseconds).

  12. Townes' contribution to nonlinear optics

    NASA Astrophysics Data System (ADS)

    Garmire, Elsa

    2015-03-01

    In honour of the Fiftieth Anniversary of the Nobel Prize in Physics, this talk introduced the contributions of Nicholas Basov and Alexei Prokhorov, who shared the prize with Charles Townes. The talk then detailed the quantum electronics research of Townes, particularly at MIT, which was related to nonlinear optics. The years from 1961 to 1968 were particularly exciting, as the ruby laser enabled a wide variety of new physics to be discovered and explored.

  13. Optical Imaging in Microstructures

    SciTech Connect

    Aker, P. M.

    2001-04-11

    This research was focused on developing morphology-dependent stimulated raman scattering (MDSRS) spectroscopy as an analytic optical imaging technique. MDSRS uses the cavity modes (called morphology dependent resonances, MDRs) associated with axisymmetric dielectric microstructures to generate nonlinear optical signals. Since different cavity modes span different regions inside the microstructure, it becomes possible to generate location-specific spectra. The information gotten from MDSRS imaging experiments is analogous with that generated from magnetic resonance imaging (MRI) studies in that spatial variations in chemical composition and molecular configuration within a structure can be mapped out. The authors demonstrated that MDSRS imaging is feasible and is free from nonlinear artifact. They did this by measuring the molecular structure variations that are present in the interfaces of 180 {micro}m dia. charged water droplets. The 4 publications that resulted from these studies are attached. From a chemical perspective a water droplet is, however, a simple thing. Will it be possible to use MDSRS imaging to study more complex systems such as combusting fuel droplets, layered polymer or glass fibers, or biological cells? The long-term goal of the research was to answer this question. The answer they have come up with is yes and no. The results on nitrate aerosols show that it is possible to do imaging studies on optically non-absorbing, ion containing systems, but that the ultimate sensitivity is dictated by ion concentration. hence systems containing large quantities of mobile ions will be difficult to look at, so this essentially eliminates being able to look at biological samples in situ. But on the positive side, organic systems, such as layered polymer and glass fibers, and combusting organic fuel droplets can be looked at with MDSRS imaging.

  14. Nonlinear Optical Studies of Bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Rao, D. V. G. L. N.; Aranda, F. J.; Chen, Z.; Akkara, J. A.; Kaplan, D. L.; Nakashima, M.

    We report interesting results on nonlinear optics at low powers in bacteriorhodopsin films with applications in all-optical switching and modulation. Chemically stabilized films of bacteriorhodopsin in a polymer matrix for which the lifetime of the excited M state is 3 to 4 orders of magnitude longer than that of water solutions of wild-type bR were used in these experiments. Due to the sensitivity of the films, very small powers of order microwatts are required for optical phase conjugation. The influence of the fast photochemical M to B transition induced by blue light on the saturation intensity, phase conjugate intensity and switching time was established. We also report our measurements of the intensity dependence of the self-focusing and self-defocusing properties of wild-type bR in water solution using the Z-scan technique with low power cw lasers at two wavelengths on either side of the absorption band. Our measurements indicate that the sign of the nonlinearity depends on the wavelength and the magnitude depends on the fluence of the incident laser beam. The observed self-focusing and defocusing is not due to the intrinsic electronic nonlinearity. The observations can be explained in terms of the Kramers-Kronig dispersion relation that relates the real and imaginary parts of the complex index of refraction.

  15. Real-time terahertz wave imaging by nonlinear optical frequency up-conversion in a 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal

    NASA Astrophysics Data System (ADS)

    Fan, Shuzhen; Qi, Feng; Notake, Takashi; Nawata, Kouji; Matsukawa, Takeshi; Takida, Yuma; Minamide, Hiroaki

    2014-03-01

    Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and arts. In this letter, we report on real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal. The active projection-imaging system consisted of (1) THz wave generation, (2) THz-near-infrared hybrid optics, (3) THz wave up-conversion, and (4) an InGaAs camera working at 60 frames per second. The pumping laser system consisted of two optical parametric oscillators pumped by a nano-second frequency-doubled Nd:YAG laser. THz-wave images of handmade samples at 19.3 THz were taken, and videos of a sample moving and a ruler stuck with a black polyethylene film moving were supplied online to show real-time ability. Thanks to the high speed and high responsivity of this technology, real-time THz imaging with a higher signal-to-noise ratio than a commercially available THz micro-bolometer camera was proven to be feasible. By changing the phase-matching condition, i.e., by changing the wavelength of the pumping laser, we suggest THz imaging with a narrow THz frequency band of interest in a wide range from approximately 2 to 30 THz is possible.

  16. Nonlinear optical interactions in semiconductors

    NASA Astrophysics Data System (ADS)

    Salour, M. M.

    1985-12-01

    The optical pumping technique in GaAs has led to the development of a novel and highly sensitive optical temperature sensor. Completed is the experiment on two photon optical pumping in ZnO. An external cavity semiconductor laser involving ZnO as a gain medium was demonstrated under two-photon excitation. This laser should have a major impact on the development of tunable blue-green radiation for submarine communication. Completed is a paper on heat buildup in semiconductor platelets. New lasers are used to explore elementary excitation in optical thin film layers of semiconductors. This has led to the first demonstration of the feasibility of room temperature operation of a tunable coherent source involving multiple quantum well material. Completed is the construction of a simple remote (non-contact) temperature sensor to directly measure heat buildup in semiconductor materials as a result of high power optical laser excitation. Finally, an experiment involving optical frequency mixing to probe electrodynamics in the GaAlAs multiple quantumwell and superlattice structures, utilizing two recently constructed tunabel laser systems,has been successful. Attempts were focused on observing a number of new optical effects including nonlinear absorption and transmission phenomena, enhanced spontaneous and stimulated light scattering processes, etc. The construction of an external cavity semiconductor HgCdTe has been successful.

  17. Nonlinear optical polymers for electro-optic signal processing

    NASA Technical Reports Server (NTRS)

    Lindsay, Geoffrey A.

    1991-01-01

    Photonics is an emerging technology, slated for rapid growth in communications systems, sensors, imagers, and computers. Its growth is driven by the need for speed, reliability, and low cost. New nonlinear polymeric materials will be a key technology in the new wave of photonics devices. Electron-conjubated polymeric materials offer large electro-optic figures of merit, ease of processing into films and fibers, ruggedness, low cost, and a plethora of design options. Several new broad classes of second-order nonlinear optical polymers were developed at the Navy's Michelson Laboratory at China Lake, California. Polar alignment in thin film waveguides was achieved by electric-field poling and Langmuir-Blodgett processing. Our polymers have high softening temperatures and good aging properties. While most of the films can be photobleached with ultraviolet (UV) light, some have excellent stability in the 500-1600 nm range, and UV stability in the 290-310 nm range. The optical nonlinear response of these polymers is subpicosecond. Electro-optic switches, frequency doublers, light modulators, and optical data storage media are some of the device applications anticipated for these polymers.

  18. Nonlinear optical studies of surfaces

    NASA Astrophysics Data System (ADS)

    Shen, Y. R.

    1994-07-01

    The possibility of using nonlinear optical processes for surface studies has attracted increasing attention in recent years. Optical second harmonic generation (SHG) and sum frequency generation (SFG), in particular, have been well accepted as viable surface probes. They have many advantages over the conventional techniques. By nature, they are highly surface-specific and has a submonolayer sensitivity. As coherent optical processes, they are capable of in-situ probing of surfaces in hostile environment as well as applicable to all interfaces accessible by light. With ultrafast pump laser pulses, they can be employed to study surface dynamic processes with a subpicosecond time resolution. These advantages have opened the door to many exciting research opportunities in surface science and technology. This paper gives a brief overview of this fast-growing new area of research. Optical SHG from a surface was first studied theoretically and experimentally in the sixties. Even the submonolayer surface sensitivity of the process was noticed fairly early. The success was, however, limited because of difficulties in controlling the experimental conditions. It was not until the early 1980's that the potential of the process for surface analysis was duly recognized. The first surface study by SHG was actually motivated by the then active search for an understanding of the intriguing surface enhanced Raman scattering (SERS). It had been suspected that the enhancement in SERS mainly came from the local-field enhancement due to local plasmon resonances and pointing rod effect on rough metal surfaces. In our view, Raman scattering is a two-photon process and is therefore a nonlinear optical effect.

  19. Nonlinear optical studies of surfaces

    SciTech Connect

    Shen, Y.R.

    1994-07-01

    The possibly of using nonlinear optical processes for surface studies has attracted increasing attention in recent years. Optical second harmonic generation (SHG) and sum frequency generation (SFG), in particular, have been well accepted as viable surface probes. They have many advantages over the conventional techniques. By nature, they are highly surface-specific and has a submonolayer sensitivity. As coherent optical processes, they are capable of in-situ probing of surfaces in hostile environment as well as applicable to all interfaces accessible by light. With ultrafast pump laser pulses, they can be employed to study surface dynamic processes with a subpicosecond time resolution. These advantages have opened the door to many exciting research opportunities in surface science and technology. This paper gives a brief overview of this fast-growing new area of research. Optical SHG from a surface was first studied theoretically and experimentally in the sixties. Even the submonolayer surface sensitivity of the process was noticed fairly early. The success was, however, limited because of difficulties in controlling the experimental conditions. It was not until the early 1980`s that the potential of the process for surface analysis was duly recognized. The first surface study by SHG was actually motivated by the then active search for an understanding of the intriguing surface enhanced Raman scattering (SERS). It had been suspected that the enhancement in SERS mainly came from the local-field enhancement due to local plasmon resonances and pointing rod effect on rough metal surfaces. In our view, Raman scattering is a two-photon process and is therefore a nonlinear optical effect.

  20. High-speed elasticity-specific nonlinear Brillouin imaging/sensing via time-resolved optical (BISTRO) measurements

    NASA Astrophysics Data System (ADS)

    Meng, Zhaokai; Ballman, Charles W.; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-03-01

    Viscoelastic properties of living cells are often directly related to the cell types and their physiological conditions. Unfortunately, all the currently existing methods for analysis of viscoelastic properties of cells, such as micropipette aspiration, atomic force microscopy and optical tweezers are intrinsically slow, limiting their applicability to study large population of cells, which are often needed for either fundamental or clinical studies. In this report, by incorporating the concept of impulsive stimulated Brillouin scattering (ISBS), we report a Brillouin Imaging and Sensing system via Time-Resolved Optical (BISTRO) measurements. We will prove the principle of the BISTRO system by presenting example microscopic measurements and flow/cell cytometry results [1].

  1. Dielectric Optical-Controllable Magnifying Lens by Nonlinear Negative Refraction.

    PubMed

    Cao, Jianjun; Shang, Ce; Zheng, Yuanlin; Feng, Yaming; Chen, Xianfeng; Liang, Xiaogan; Wan, Wenjie

    2015-01-01

    A simple optical lens plays an important role for exploring the microscopic world in science and technology by refracting light with tailored spatially varying refractive indices. Recent advancements in nanotechnology enable novel lenses, such as, superlens and hyperlens, with sub-wavelength resolution capabilities by specially designed materials' refractive indices with meta-materials and transformation optics. However, these artificially nano- or micro-engineered lenses usually suffer high losses from metals and are highly demanding in fabrication. Here, we experimentally demonstrate, for the first time, a nonlinear dielectric magnifying lens using negative refraction by degenerate four-wave mixing in a plano-concave glass slide, obtaining magnified images. Moreover, we transform a nonlinear flat lens into a magnifying lens by introducing transformation optics into the nonlinear regime, achieving an all-optical controllable lensing effect through nonlinear wave mixing, which may have many potential applications in microscopy and imaging science. PMID:26149952

  2. Dielectric Optical-Controllable Magnifying Lens by Nonlinear Negative Refraction

    NASA Astrophysics Data System (ADS)

    Cao, Jianjun; Shang, Ce; Zheng, Yuanlin; Feng, Yaming; Chen, Xianfeng; Liang, Xiaogan; Wan, Wenjie

    2015-07-01

    A simple optical lens plays an important role for exploring the microscopic world in science and technology by refracting light with tailored spatially varying refractive indices. Recent advancements in nanotechnology enable novel lenses, such as, superlens and hyperlens, with sub-wavelength resolution capabilities by specially designed materials’ refractive indices with meta-materials and transformation optics. However, these artificially nano- or micro-engineered lenses usually suffer high losses from metals and are highly demanding in fabrication. Here, we experimentally demonstrate, for the first time, a nonlinear dielectric magnifying lens using negative refraction by degenerate four-wave mixing in a plano-concave glass slide, obtaining magnified images. Moreover, we transform a nonlinear flat lens into a magnifying lens by introducing transformation optics into the nonlinear regime, achieving an all-optical controllable lensing effect through nonlinear wave mixing, which may have many potential applications in microscopy and imaging science.

  3. Dielectric Optical-Controllable Magnifying Lens by Nonlinear Negative Refraction

    PubMed Central

    Cao, Jianjun; Shang, Ce; Zheng, Yuanlin; Feng, Yaming; Chen, Xianfeng; Liang, Xiaogan; Wan, Wenjie

    2015-01-01

    A simple optical lens plays an important role for exploring the microscopic world in science and technology by refracting light with tailored spatially varying refractive indices. Recent advancements in nanotechnology enable novel lenses, such as, superlens and hyperlens, with sub-wavelength resolution capabilities by specially designed materials’ refractive indices with meta-materials and transformation optics. However, these artificially nano- or micro-engineered lenses usually suffer high losses from metals and are highly demanding in fabrication. Here, we experimentally demonstrate, for the first time, a nonlinear dielectric magnifying lens using negative refraction by degenerate four-wave mixing in a plano-concave glass slide, obtaining magnified images. Moreover, we transform a nonlinear flat lens into a magnifying lens by introducing transformation optics into the nonlinear regime, achieving an all-optical controllable lensing effect through nonlinear wave mixing, which may have many potential applications in microscopy and imaging science. PMID:26149952

  4. Optical nonlinearities in plasmonic metamaterials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zayats, Anatoly V.

    2016-04-01

    Metals exhibit strong and fast nonlinearities making metallic, plasmonic, structures very promising for ultrafast all-optical applications at low light intensities. Combining metallic nanostructures in metamaterials provides additional functionalities via prospect of precise engineering of spectral response and dispersion. From this point of view, hyperbolic metamaterials, in particular those based on plasmonic nanorod arrays, provide wealth of exciting possibilities in nonlinear optics offering designed linear and nonlinear properties, polarization control, spontaneous emission control and many others. Experiments and modeling have already demonstrated very strong Kerr-nonlinear response and its ultrafast recovery due to the nonlocal nature of the plasmonic mode of the metamaterial, so that small changes in the permittivity of the metallic component under the excitation modify the nonlocal response that in turn leads to strong changes of the metamaterial transmission. In this talk, we will discuss experimental studies and numerical modeling of second- and third-order nonlinear optical processes in hyperbolic metamaterials based on metallic nanorods and other plasmonic systems where coupling between the resonances plays important role in defining nonlinear response. Second-harmonic generation and ultrafast Kerr-type nonlinearity originating from metallic component of the metamaterial will be considered, including nonlinear magneto-optical effects. Nonlinear optical response of stand-alone as well as integrated metamaterial components will be presented. Some of the examples to be discussed include nonlinear polarization control, nonlinear metamaterial integrated in silicon photonic circuitry and second-harmonic generation, including magneto-optical effects.

  5. Nonlinear Polarimetric Microscopy for Biomedical Imaging

    NASA Astrophysics Data System (ADS)

    Samim, Masood

    A framework for the nonlinear optical polarimetry and polarimetric microscopy is developed. Mathematical equations are derived in terms of linear and nonlinear Stokes Mueller formalism, which comprehensively characterize the polarization properties of the incoming and outgoing radiations, and provide structural information about the organization of the investigated materials. The algebraic formalism developed in this thesis simplifies many predictions for a nonlinear polarimetry study and provides an intuitive understanding of various polarization properties for radiations and the intervening medium. For polarimetric microscopy experiments, a custom fast-scanning differential polarization microscope is developed, which is also capable of real-time three-dimensional imaging. The setup is equipped with a pair of high-speed resonant and galvanometric scanning mirrors, and supplemented by advanced adaptive optics and data acquisition modules. The scanning mirrors when combined with the adaptive optics deformable mirror enable fast 3D imaging. Deformable membrane mirrors and genetic algorithm optimization routines are employed to improve the imaging conditions including correcting the optical aberrations, maximizing signal intensities, and minimizing point-spread-functions of the focal volume. A field-programmable-gate array (FPGA) chip is exploited to rapidly acquire and process the multidimensional data. Using the nonlinear optical polarimetry framework and the home-built polarization microscope, a few biologically important tissues are measured and analyzed to gain insight as to their structure and dynamics. The structure and distribution of muscle sarcomere myosins, connective tissue collagen, carbohydrate-rich starch, and fruit fly eye retinal molecules are characterized with revealing polarization studies. In each case, using the theoretical framework, polarization sensitive data are analyzed to decipher the molecular orientations and nonlinear optical

  6. Ultrafast optical pulse delivery with fibers for nonlinear microscopy

    PubMed Central

    Kim, Daekeun; Choi, Heejin; Yazdanfar, Siavash; So, Peter T. C.

    2008-01-01

    Nonlinear microscopies including multiphoton excitation fluorescence microscopy and multiple-harmonic generation microscopy have recently gained popularity for cellular and tissue imaging. The optimization of these imaging methods for minimally invasive use will require optical fibers to conduct light into tight space where free space delivery is difficult. The delivery of high peak power laser pulses with optical fibers is limited by dispersion resulting from nonlinear refractive index responses. In this paper, we characterize a variety of commonly used optical fibers in terms of how they affect pulse profile and imaging performance of nonlinear microscopy; the following parameters are quantified: spectral bandwidth and temporal pulse width, two-photon excitation efficiency, and optical resolution. A theoretical explanation for the measured performance of these is also provided. PMID:18816597

  7. Telescopic systems with dynamic nonlinear optical correction for distortions

    SciTech Connect

    Vasil'ev, Michail V; Venediktov, Vladimir Yu; Leshchev, Alexey A

    2001-01-31

    The review of basic achievements in the field of non-linear adaptive optics is presented. In particular, schematics and properties of adaptive optical telescopes considered in which the image distortions introduced by defects of the primary mirror and other optical elements are compensated by nonlinear optical methods. The conventional methods of laser optics, such as phase conjugation and dynamic holography, make it possible both to solve the problems of classical (imaging) optics related to the building of telescopes for imaging remote objects with high resolution, which are based on large, light-weight or sectional mirrors, and create the systems that produce laser beams with the high-quality wave front. The basic designs of such telescopes are considered and the possibilities of corrections for distortions in them are analysed and confirmed by experiments. (review)

  8. Nonlinear spectral imaging of biological tissues

    NASA Astrophysics Data System (ADS)

    Palero, J. A.

    2007-07-01

    The work presented in this thesis demonstrates live high resolution 3D imaging of tissue in its native state and environment. The nonlinear interaction between focussed femtosecond light pulses and the biological tissue results in the emission of natural autofluorescence and second-harmonic signal. Because biological intrinsic emission is generally very weak and extends from the ultraviolet to the visible spectral range, a broad-spectral range and high sensitivity 3D spectral imaging system is developed. Imaging the spectral characteristics of the biological intrinsic emission reveals the structure and biochemistry of the cells and extra-cellular components. By using different methods in visualizing the spectral images, discrimination between different tissue structures is achieved without the use of any stain or fluorescent label. For instance, RGB real color spectral images of the intrinsic emission of mouse skin tissues show blue cells, green hair follicles, and purple collagen fibers. The color signature of each tissue component is directly related to its characteristic emission spectrum. The results of this study show that skin tissue nonlinear intrinsic emission is mainly due to the autofluorescence of reduced nicotinamide adenine dinucleotide (phosphate), flavins, keratin, melanin, phospholipids, elastin and collagen and nonlinear Raman scattering and second-harmonic generation in Type I collagen. In vivo time-lapse spectral imaging is implemented to study metabolic changes in epidermal cells in tissues. Optical scattering in tissues, a key factor in determining the maximum achievable imaging depth, is also investigated in this work.

  9. Synthesizing Diacetylenes With Nonlinear Optical Properties

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Frazier, Donald P.; Paley, Mark S.

    1993-01-01

    Diacetylene compounds being investigated to determine whether they have nonlinear optical properties making them useful for four-wave mixing, generation of third harmonics, phase conjugation, and like. Diacetylene monomers synthesized by sequences of chemical reactions. Monomers polymerized by ultraviolet light, forming potentially useful nonlinear optical materials.

  10. What Is Optical Imaging?

    ERIC Educational Resources Information Center

    Hespos, Susan J.

    2010-01-01

    This article introduces a promising new methodology called optical imaging. Optical imaging is used for measuring changes in cortical blood flow due to functional activation. The article outlines the pros and cons of using optical imaging for studying the brain correlates of perceptual, cognitive, and language development in infants and young…

  11. Strong electron correlation and nonlinear optics

    NASA Astrophysics Data System (ADS)

    Ghosh, Haranath

    2012-07-01

    Based on experimental and theoretical research during the last decade, giant optical nonlinearities found in Mott-Hubbard insulators like Sr2CuO3,Ca2CuO3, Nickel halides ([Ni(chxn)2X]X2 where X = Br, Cl and `chxn' refers to cyclohexanediamine) are presented. These materials are reported to be potential materials for all optical switching devices. The occurrence of nearly degenerate lowest one- and two-photon states, strong Coulomb correlation and strong dipole coupling between the one- and two-photon states are believed to be the reason for such colossal optical nonlinearities in these systems. In some of these materials (at least), the two photon state is below the one-photon state. This leads to the possibility that such material can be excited to the lowest optical state by shinning laser of suitable wavelength, the populations thus generated decays to the two-photon state at ultrafast short time. Thus nonlinear measurements can be made from an excited state (we call as excited state nonlinear optical properties). One dimensional strongly correlated materials are predicted to have several orders-of-magnitude larger excited state optical non-linearities in comparison to that from the ground state, in the wavelength region suitable for terahertz communications. A large number of measurable nonlinear optical properties like Two Photon absorption, Photo induced absorption, Third Harmonic generation, Stimulated Raman Scattering are obtained theoretically and compared with available experimental observations. Then a large number excited state nonlinear optical properties are predicted which are experimentally measurable. We emphasize that the mechanism of nonlinear optics in one dimensional Mott-Hubbard insulators is different from that of the π-conjugated polymers — in the former spin excitation play an important role. We argue from detailed understanding of nonlinear optics of π-conjugated systems that some features in the Third Harmonic Generation

  12. Nonlinear optical properties of composite materials

    NASA Technical Reports Server (NTRS)

    Haus, Joseph W.; Inguva, Ramarao

    1991-01-01

    The optical properties of a new class of composite nonlinear materials composed of coated grains, such as cadmium sulfide with a silver coating, are examined. These materials exhibit intrinsic optical bistability and resonantly enhanced conjugate reflectivity. The threshold for intrinsic optical bistability is low enough for practical applications in optical communications and optical computing. Some problems associated with the fabrication of these materials are addressed. Based on preliminary results, switching times are expected to be in the subpicosecond range.

  13. Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

    NASA Astrophysics Data System (ADS)

    Lanin, Aleksandr A.; Fedotov, Il'ya V.; Sidorov-Biryukov, Dmitrii A.; Doronina-Amitonova, Lyubov V.; Ivashkina, Olga I.; Zots, Marina A.; Sun, Chi-Kuang; Ömer Ilday, F.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

    2012-03-01

    Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-μm-core hollow PCF compresses 510-fs, 1070-nm light pulses to a pulse width of about 110 fs, providing a peak power in excess of 5 MW. The compressed PCF output is employed to induce a local photodisruption of corpus callosum tissues in mouse brain and is used to generate the third harmonic in brain tissues, which is captured by the PCF and delivered to a detector through the PCF cladding.

  14. Ring for test of nonlinear integrable optics

    SciTech Connect

    Valishev, A.; Nagaitsev, S.; Kashikhin, V.; Danilov, V.; /SNS Project, Oak Ridge

    2011-03-01

    Nonlinear optics is a promising idea potentially opening the path towards achieving super high beam intensities in circular accelerators. Creation of a tune spread reaching 50% of the betatron tune would provide strong Landau damping and make the beam immune to instabilities. Recent theoretical work has identified a possible way to implement stable nonlinear optics by incorporating nonlinear focusing elements into a specially designed machine lattice. In this report we propose the design of a test accelerator for a proof-of-principle experiment. We discuss possible studies at the machine, requirements on the optics stability and sensitivity to imperfections.

  15. Nonlinear quantum optical properties of graphene

    NASA Astrophysics Data System (ADS)

    Semnani, Behrooz; Hamed Majedi, Amir; Safavi-Naeini, Safieddin

    2016-03-01

    We present a semiclassical theory of the linear and nonlinear optical response of graphene. The emphasis is placed on the nonlinear optical response of graphene from the standpoint of the underlying chiral symmetry. The Bloch quasiparticles in the low-energy limit around the degeneracy points are dominantly chiral. It is shown that this chiral behavior in conjunction with scale invariance in graphene around the Dirac points results in the strong nonlinear optical response. Explicit expressions for the linear and nonlinear conductivity tensors are derived based on semiconductor Bloch equations (SBEs). The linear terms agree with the result of Kubo formulation. The three main additive mechanisms contribute in the nonlinear optical response of graphene: pure intraband, pure interband and the interplay between them. For each contribution, an explicit response function is derived. The Kerr-type nonlinearity of graphene is then numerically studied and it is demonstrated that the nonlinear refractive index of graphene can be tuned and enhanced by applying a gate voltage. It is also discussed that a strong Kerr nonlinearity can be achieved in a gated graphene monolayer. However, this nonlinearity is accompanied with a significant amount of absorption loss.

  16. Compressive Optical Image Encryption

    PubMed Central

    Li, Jun; Sheng Li, Jiao; Yang Pan, Yang; Li, Rong

    2015-01-01

    An optical image encryption technique based on compressive sensing using fully optical means has been proposed. An object image is first encrypted to a white-sense stationary noise pattern using a double random phase encoding (DRPE) method in a Mach-Zehnder interferometer. Then, the encrypted image is highly compressed to a signal using single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the encrypted image is reconstructed well via compressive sensing theory, and the original image can be decrypted with three reconstructed holograms and the correct keys. The numerical simulations show that the method is effective and suitable for optical image security transmission in future all-optical networks because of the ability of completely optical implementation and substantially smaller hologram data volume. PMID:25992946

  17. Compressive optical image encryption.

    PubMed

    Li, Jun; Sheng Li, Jiao; Yang Pan, Yang; Li, Rong

    2015-01-01

    An optical image encryption technique based on compressive sensing using fully optical means has been proposed. An object image is first encrypted to a white-sense stationary noise pattern using a double random phase encoding (DRPE) method in a Mach-Zehnder interferometer. Then, the encrypted image is highly compressed to a signal using single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the encrypted image is reconstructed well via compressive sensing theory, and the original image can be decrypted with three reconstructed holograms and the correct keys. The numerical simulations show that the method is effective and suitable for optical image security transmission in future all-optical networks because of the ability of completely optical implementation and substantially smaller hologram data volume. PMID:25992946

  18. Nonlinear secret image sharing scheme.

    PubMed

    Shin, Sang-Ho; Lee, Gil-Je; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2 m⌉ bit-per-pixel (bpp), respectively. PMID:25140334

  19. Nonlinear Secret Image Sharing Scheme

    PubMed Central

    Shin, Sang-Ho; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2⁡m⌉ bit-per-pixel (bpp), respectively. PMID:25140334

  20. Nonlinear optical studies of a novel pyrazoline

    NASA Astrophysics Data System (ADS)

    Janardhana, K.; Ravindrachary, V.; Kumar, P. C. Rajesh; Umesh, G.; Manjunatha, K. B.; Ismayil

    2012-06-01

    A novel pyrazoline, 3-(phenyl)-5-(4-hydroxyphenyl)-1-(2, 4-dinitrophenyl)-2-pyrazoline (PHDP) was synthesized using standard method and its chemical structure was confirmed using FTIR studies. The linear and non linear optical properties of the compound were studied using UV-Vis and Z-scan techniques. UV-Vis spectrum shows that the compound is transparent in the visible region and absorption in the UV region. The z-scan study shows that the compound possesses third and higher order optical nonlinearity. The calculated optical absorption cross sections indicate that the operating nonlinear mechanism is reverse saturable absorption type. The real part of the third-order nonlinear optical susceptibility χ3 was estimated and the closed aperture data shows that PHDP possess negative nonlinearity.

  1. Split image optical display

    DOEpatents

    Veligdan, James T.

    2007-05-29

    A video image is displayed from an optical panel by splitting the image into a plurality of image components, and then projecting the image components through corresponding portions of the panel to collectively form the image. Depth of the display is correspondingly reduced.

  2. Split image optical display

    DOEpatents

    Veligdan, James T.

    2005-05-31

    A video image is displayed from an optical panel by splitting the image into a plurality of image components, and then projecting the image components through corresponding portions of the panel to collectively form the image. Depth of the display is correspondingly reduced.

  3. All-optical switching in optically induced nonlinear waveguide couplers

    SciTech Connect

    Diebel, Falko Boguslawski, Martin; Rose, Patrick; Denz, Cornelia; Leykam, Daniel; Desyatnikov, Anton S.

    2014-06-30

    We experimentally demonstrate all-optical vortex switching in nonlinear coupled waveguide arrays optically induced in photorefractive media. Our technique is based on multiplexing of nondiffracting Bessel beams to induce various types of waveguide configurations. Using double- and quadruple-well potentials, we demonstrate precise control over the coupling strength between waveguides, the linear and nonlinear dynamics and symmetry-breaking bifurcations of guided light, and a power-controlled optical vortex switch.

  4. Reflective optical imaging system

    DOEpatents

    Shafer, David R.

    2000-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements are characterized in order from object to image as convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention increases the slit dimensions associated with ringfield scanning optics, improves wafer throughput and allows higher semiconductor device density.

  5. Nonlinear waveguide optics and photonic crystal fibers.

    PubMed

    Knight, J C; Skryabin, D V

    2007-11-12

    Focus Serial: Frontiers of Nonlinear Optics

    Optical fibers and waveguides provide unique and distinct environments for nonlinear optics, because of the combination of high intensities, long interaction lengths, and control of the propagation constants. They are also becoming of technological importance. The topic has a long history but continues to generate rapid development, most recently through the invention of the new forms of optical fiber collectively known as photonic crystal fibers. Some of the discoveries and ideas from the new fibers look set to have lasting influence in the broader field of guided-wave nonlinear optics. In this paper we introduce some of these ideas. PMID:19550822

  6. One-step shell polymerization of inorganic nanoparticles and their applications in SERS/nonlinear optical imaging, drug delivery, and catalysis

    PubMed Central

    Liu, Tzu-Ming; Yu, Jiashing; Chang, C. Allen; Chiou, Arthur; Chiang, Huihua Kenny; Chuang, Yu-Chun; Wu, Cheng-Han; Hsu, Che-Hao; Chen, Po-An; Huang, Chih-Chia

    2014-01-01

    Surface functionalized nanoparticles have found their applications in several fields including biophotonics, nanobiomedicine, biosensing, drug delivery, and catalysis. Quite often, the nanoparticle surfaces must be post-coated with organic or inorganic layers during the synthesis before use. This work reports a generally one-pot synthesis method for the preparation of various inorganic-organic core-shell nanostructures (Au@polymer, Ag@polymer, Cu@polymer, Fe3O4@polymer, and TiO2@polymer), which led to new optical, magnetic, and catalytic applications. This green synthesis involved reacting inorganic precursors and poly(styrene-alt-maleic acid). The polystyrene blocks separated from the external aqueous environment acting as a hydrophobic depot for aromatic drugs and thus illustrated the integration of functional nanoobjects for drug delivery. Among these nanocomposites, the Au@polymer nanoparticles with good biocompatibility exhibited shell-dependent signal enhancement in the surface plasmon resonance shift, nonlinear fluorescence, and surface-enhanced Raman scattering properties. These unique optical properties were used for dual-modality imaging on the delivery of the aromatic photosensitizer for photodynamic therapy to HeLa cells. PMID:24998932

  7. One-step shell polymerization of inorganic nanoparticles and their applications in SERS/nonlinear optical imaging, drug delivery, and catalysis

    NASA Astrophysics Data System (ADS)

    Liu, Tzu-Ming; Yu, Jiashing; Chang, C. Allen; Chiou, Arthur; Chiang, Huihua Kenny; Chuang, Yu-Chun; Wu, Cheng-Han; Hsu, Che-Hao; Chen, Po-An; Huang, Chih-Chia

    2014-07-01

    Surface functionalized nanoparticles have found their applications in several fields including biophotonics, nanobiomedicine, biosensing, drug delivery, and catalysis. Quite often, the nanoparticle surfaces must be post-coated with organic or inorganic layers during the synthesis before use. This work reports a generally one-pot synthesis method for the preparation of various inorganic-organic core-shell nanostructures (Au@polymer, Ag@polymer, Cu@polymer, Fe3O4@polymer, and TiO2@polymer), which led to new optical, magnetic, and catalytic applications. This green synthesis involved reacting inorganic precursors and poly(styrene-alt-maleic acid). The polystyrene blocks separated from the external aqueous environment acting as a hydrophobic depot for aromatic drugs and thus illustrated the integration of functional nanoobjects for drug delivery. Among these nanocomposites, the Au@polymer nanoparticles with good biocompatibility exhibited shell-dependent signal enhancement in the surface plasmon resonance shift, nonlinear fluorescence, and surface-enhanced Raman scattering properties. These unique optical properties were used for dual-modality imaging on the delivery of the aromatic photosensitizer for photodynamic therapy to HeLa cells.

  8. Squeezing spectra for nonlinear optical systems

    NASA Technical Reports Server (NTRS)

    Collett, M. J.; Walls, D. F.

    1985-01-01

    The squeezing spectra for the output fields of several intracavity nonlinear optical systems are obtained. It is shown that at critical points, e.g., the turning points for optical bistability, the threshold for parametric oscillation, and the self-pulsing instability in second-harmonic generation, perfect squeezing in the output field is, in principle, possible.

  9. Enhancing retinal images by nonlinear registration

    NASA Astrophysics Data System (ADS)

    Molodij, G.; Ribak, E. N.; Glanc, M.; Chenegros, G.

    2015-05-01

    Being able to image the human retina in high resolution opens a new era in many important fields, such as pharmacological research for retinal diseases, researches in human cognition, nervous system, metabolism and blood stream, to name a few. In this paper, we propose to share the knowledge acquired in the fields of optics and imaging in solar astrophysics in order to improve the retinal imaging in the perspective to perform a medical diagnosis. The main purpose would be to assist health care practitioners by enhancing the spatial resolution of the retinal images and increase the level of confidence of the abnormal feature detection. We apply a nonlinear registration method using local correlation tracking to increase the field of view and follow structure evolutions using correlation techniques borrowed from solar astronomy technique expertise. Another purpose is to define the tracer of movements after analyzing local correlations to follow the proper motions of an image from one moment to another, such as changes in optical flows that would be of high interest in a medical diagnosis.

  10. Noncritical microemulsion as nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Vicari, Luciano R. M.; Barone, A. C.

    2002-11-01

    Water in oil microemulsions are systems of spherical droplets of water coated by a monolayer of surfactant molecules, immersed in oil. Initially we have studied the optical nonlinear behavior of water in oil microemulsion by the Self-Phase-Modulation of a gaussian laser beam by an optically thin film. The material is WAD (water/AOT/decane, where AOT denotes sodium-bis-di-ethyl-sulfosuccinate) far from critical points and near the percolative transition from electrically insulating to electrically conducting. We have observed optical nonlinearity in the L2 area of the phase diagram, near the percolation line and far from the one-phase two-phase boundary line. In this point, the material turbidity is very low. Strong optical nonlinearity has been reported. Nonlinear optical effects in a Water/AOT/Decane (WAD) microemulsion have been experimentally studied also in a pump probe configuration. We detect the variation of the on axis optical intensity of the probe beam as generated by the concentration profile induced in an optically thin film of microemulsion by the pump beam. Results seem to suggest the hypothesis of a chain like shape of the clusters.

  11. Coherent perfect absorption in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Zheng, Yuanlin; Wan, Wenjie; Chen, Xianfeng

    2013-02-01

    Recently, a concept of time reversed lasing or coherent perfect absorber (CPA) has been proposed by A. D. Stone and co-workers, and was shortly experimentally demonstrated by them. The CPA system is illuminated coherently and monochromatically by the time reverse of the output of a lasing mode and the incident radiation is perfectly absorbed. Shortly afterwards, Stefano Longhi extended the idea to realize a CPA for colored incident light, and have theoretically shown that the time reversal of optical parametric oscillation (OPO) in a nonlinear medium could also realize a colored CPA for incident signal and idler fields which can be seemed as a kind of nonlinear CPA. Here we present the realization of such time-reversed processes in nonlinear optics regime, including time-reversed second harmonic generation (SHG) for coherent absorption at harmonic frequency of the pump and time-reversed optical parametric amplification (OPA) for coherent attenuation of colored travelling optical fields. Time reversed SHG is carried out at both phase matching and mismatching conditions, which shows parametric near perfect absorption at the harmonic frequency of the pump. The time reversal of OPA is demonstrated experimentally in a nonlinear medium to form a coherent absorber for perpendicularly polarized signal and idler travelling waves, realizing in the condition of OPA by a type II phase matching scheme. The absorption of signal/idler pair occurs at some specific phase difference. This is the first experimental demonstration of coherent absorption processes in nonlinear optics regime.

  12. Giant optical nonlinearity of plasmonic nanostructures

    SciTech Connect

    Melentiev, P N; Afanasev, A E; Balykin, V I

    2014-06-30

    The experimental studies of giant optical nonlinearity of single metal nanostructures are briefly reviewed. A new hybrid nanostructure – split-hole resonator (SHR) – is investigated. This structure is characterised by a record-high efficiency of third-harmonic generation and multiphoton luminescence (its nonlinearity exceeds that of a single nanohole by five orders of magnitude) and an unprecedently high sensitivity to light polarisation (extinction coefficient 4 × 10{sup 4}). (extreme light fields and their applications)

  13. Nonlinear optical techniques for surface studies. [Monolayers

    SciTech Connect

    Shen, Y.R.

    1981-09-01

    Recent effort in developing nonlinear optical techniques for surface studies is reviewed. Emphasis is on monolayer detection of adsorbed molecules on surfaces. It is shown that surface coherent antiStokes Raman scattering (CARS) with picosecond pulses has the sensitivity of detecting submonolayer of molecules. On the other hand, second harmonic or sum-frequency generation is also sensitive enough to detect molecular monolayers. Surface-enhanced nonlinear optical effects on some rough metal surfaces have been observed. This facilitates the detection of molecular monolayers on such surfaces, and makes the study of molecular adsorption at a liquid-metal interface feasible. Advantages and disadvantages of the nonlinear optical techniques for surface studies are discussed.

  14. Topological aspects of nonlinear optical responses

    NASA Astrophysics Data System (ADS)

    Morimoto, Takahiro; Nagaosa, Naoto

    There are a variety of nonlinear optical effects including higher harmonic generations, photovoltaic effects, and nonlinear Kerr rotations. A recent remarkable progress in the photovoltaic effect is the high efficiency solar cell action in perovskite oxides without inversion symmetry. The crystal structure lacking inversion replaces the role of artificial structures such as p-n junctions in conventional solar cells. One of the proposed mechanisms for this phenomenon is the shift-current which is supported by a band structure lacking inversion and is related to the Berry connection of Bloch wavefunctions. Motivated by these, we explore topological aspects of the nonlinear optical responses. To this end, we employ the Keldysh method combined with the Floquet formalism, where effective band structures can be defined under an electric field periodic in time. This enables us to describe the shift-current, nonlinear Kerr rotation, photovoltaic effect, and the photo-induced change in the order parameters in a unified fashion. We connect these nonlinear optical responses to topological quantities involving the Berry connection and Berry curvature. It is found that vector fields defined with the Berry connections in the space of momentum and/or parameters govern the nonlinear responses.

  15. Optical nonlinearity of HBI in different solvents

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Ma, Lina; Geng, Yaohui; Zhang, Siwen; Wang, Zhe; Cheng, Xiaoman

    2014-04-01

    2-(2'-Hydroxyphenyl) benzimidazole (HBI) is one kind of organic molecules featuring excited-state proton transfer (ESPT). The nonlinear optical properties of 2-(2'-hydroxyphenyl) benzimidazole (HBI) in different polar solvents were investigated by means of Z-scan technique under the excitation of the 1064 nm picoseconds laser pulse. The experimental results show that the nonlinear refractive indices decrease with the enhancement of the polarity of the solvent. The nonlinear refractive indices sensitive to the solvent polarity allow them to be widely used for the optoelectronic devices.

  16. Complex geometrical optics of nonlinear inhomogeneous fibres

    NASA Astrophysics Data System (ADS)

    Berczynski, Pawel

    2011-03-01

    This paper analyses the Gaussian beam (GB) evolution in nonlinear fibres with special attention given to the influence of the initial curvature of the wavefront and to the fibres' permittivity profile. The analysis is performed in the framework of paraxial complex geometrical optics (PCGO). This method reduces the problem of GB evolution in nonlinear and inhomogeneous media to the solution of ordinary differential equations, which can be easily solved either analytically or numerically. It is shown that the PCGO approach radically simplifies modelling of nonlinear phenomena in fibres as compared with standard methods of nonlinear optics such as the variational method approach and the method of moments. It is shown that the PCGO method readily supplies the solution of the nonlinear Schrödinger equation (NLS) for a self-focusing fibre with a focusing permittivity profile and provides a number of new results. The discussion on the interplay between the nonlinear (self-focusing and self-defocusing) and linear (focusing and defocusing) components of the total permittivity demonstrates the new possibilities to limit the collapse phenomenon in nonlinear fibres of Kerr type taking into account the effect of initial beam divergence.

  17. Label-free imaging and quantitative chemical analysis of Alzheimer's disease brain samples with multimodal multiphoton nonlinear optical microspectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jang Hyuk; Kim, Dae Hwan; Song, Woo Keun; Oh, Myoung-Kyu; Ko, Do-Kyeong

    2015-05-01

    We developed multimodal multiphoton microspectroscopy using a small-diameter probe with gradient-index lenses and applied it to unstained Alzheimer's disease (AD) brain samples. Our system maintained the image quality and spatial resolution of images obtained using an objective lens of similar numerical aperture. Multicolor images of AD brain samples were obtained simultaneously by integrating two-photon excited fluorescence and second-harmonic generation on a coherent anti-Stokes Raman scattering (CARS) microendoscope platform. Measurements of two hippocampal regions, the cornus ammonis-1 and dentate gyrus, revealed more lipids, amyloid fibers, and collagen in the AD samples than in the normal samples. Normal and AD brains were clearly distinguished by a large spectral difference and quantitative analysis of the CH mode using CARS microendoscope spectroscopy. We expect this system to be an important diagnosis tool in AD research.

  18. Probing membrane potential with nonlinear optics.

    PubMed Central

    Bouevitch, O; Lewis, A; Pinevsky, I; Wuskell, J P; Loew, L M

    1993-01-01

    The nonlinear optical phenomenon of second harmonic generation is shown to have intrinsic sensitivity to the voltage across a biological membrane. Our results demonstrate that this second order nonlinear optical process can be used to monitor membrane voltage with excellent signal to noise and other crucial advantages. These advantages suggest extensive use of this novel approach as an important new tool in elucidating membrane potential changes in biological systems. For this first demonstration of the effect we use a chiral styryl dye which exhibits gigantic second harmonic signals. Possible mechanisms of the voltage dependence of the second harmonic signal are discussed. PMID:8218895

  19. Polydiacetylene thin films for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Paley, Mark S.

    1993-01-01

    One very promising class of organic compounds for nonlinear optical (NLO) applications are polydiacetylenes, which are novel in that they are highly conjugated polymers which can also be crystalline. Polydiacetylenes offer several advantages over other organic materials: because of their highly conjugated electronic structures, they are capable of possessing large optical nonlinearities with fast response times; because they are crystalline, they can be highly ordered, which is essential for optimizing their NLO properties; and, last, because they are polymeric, they can be formed as thin films, which are useful for device fabrication. We have actively been carrying out ground-based research on several compounds of interest.

  20. Tunable nanowire nonlinear optical probe

    SciTech Connect

    Nakayama, Yuri; Pauzauskie, Peter J.; Radenovic, Aleksandra; Onorato, Robert M.; Saykally, Richard J.; Liphardt, Jan; Yang, Peidong

    2008-02-18

    One crucial challenge for subwavelength optics has been thedevelopment of a tunable source of coherent laser radiation for use inthe physical, information, and biological sciences that is stable at roomtemperature and physiological conditions. Current advanced near-fieldimaging techniques using fiber-optic scattering probes1,2 have alreadyachieved spatial resolution down to the 20-nm range. Recently reportedfar-field approaches for optical microscopy, including stimulatedemission depletion (STED)3, structured illumination4, and photoactivatedlocalization microscopy (PALM)5, have also enabled impressive,theoretically-unlimited spatial resolution of fluorescent biomolecularcomplexes. Previous work with laser tweezers6-8 has suggested the promiseof using optical traps to create novel spatial probes and sensors.Inorganic nanowires have diameters substantially below the wavelength ofvisible light and have unique electronic and optical properties9,10 thatmake them prime candidates for subwavelength laser and imagingtechnology. Here we report the development of an electrode-free,continuously-tunable coherent visible light source compatible withphysiological environments, from individual potassium niobate (KNbO3)nanowires. These wires exhibit efficient second harmonic generation(SHG), and act as frequency converters, allowing the local synthesis of awide range of colors via sum and difference frequency generation (SFG,DFG). We use this tunable nanometric light source to implement a novelform of subwavelength microscopy, in which an infrared (IR) laser is usedto optically trap and scan a nanowire over a sample, suggesting a widerange of potential applications in physics, chemistry, materials science,and biology.

  1. Nonlinear image filtering within IDP++

    SciTech Connect

    Lehman, S.K.; Wieting, M.G.; Brase, J.M.

    1995-02-09

    IDP++, image and data processing in C++, is a set of a signal processing libraries written in C++. It is a multi-dimension (up to four dimensions), multi-data type (implemented through templates) signal processing extension to C++. IDP++ takes advantage of the object-oriented compiler technology to provide ``information hiding.`` Users need only know C, not C++. Signals or data sets are treated like any other variable with a defined set of operators and functions. We here some examples of the nonlinear filter library within IDP++. Specifically, the results of MIN, MAX median, {alpha}-trimmed mean, and edge-trimmed mean filters as applied to a real aperture radar (RR) and synthetic aperture radar (SAR) data set.

  2. Rotational Doppler effect in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

  3. Assessment of fibrotic liver disease with multimodal nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Lu, Fake; Zheng, Wei; Tai, Dean C. S.; Lin, Jian; Yu, Hanry; Huang, Zhiwei

    2010-02-01

    Liver fibrosis is the excessive accumulation of extracellular matrix proteins such as collagens, which may result in cirrhosis, liver failure, and portal hypertension. In this study, we apply a multimodal nonlinear optical microscopy platform developed to investigate the fibrotic liver diseases in rat models established by performing bile duct ligation (BDL) surgery. The three nonlinear microscopy imaging modalities are implemented on the same sectioned tissues of diseased model sequentially: i.e., second harmonic generation (SHG) imaging quantifies the contents of the collagens, the two-photon excitation fluorescence (TPEF) imaging reveals the morphology of hepatic cells, while coherent anti-Stokes Raman scattering (CARS) imaging maps the distributions of fats or lipids quantitatively across the tissue. Our imaging results show that during the development of liver fibrosis (collagens) in BDL model, fatty liver disease also occurs. The aggregated concentrations of collagen and fat constituents in liver fibrosis model show a certain correlationship between each other.

  4. Subsurface diffuse optical tomography can localize absorber and fluorescent objects but recovered image sensitivity is nonlinear with depth

    NASA Astrophysics Data System (ADS)

    Kepshire, Dax S.; Davis, Scott C.; Dehghani, Hamid; Paulsen, Keith D.; Pogue, Brian W.

    2007-04-01

    Subsurface tomography with diffuse light has been investigated with a noncontact approach to characterize the performance of absorption and fluorescence imaging. Using both simulations and experiments, the reconstruction of local subsurface heterogeneity is demonstrated, but the recovery of target size and fluorophore concentration is not linear when changes in depth occur, whereas the mean position of the object for experimental fluorescent and absorber targets is accurate to within 0.5 and 1.45 mm when located within the first 10 mm below the surface. Improvements in the linearity of the response with depth appear to remain challenging and may ultimately limit the approach to detection rather than characterization applications. However, increases in tissue curvature and/or the addition of prior information are expected to improve the linearity of the response. The potential for this type of imaging technique to serve as a surgical guide is highlighted.

  5. Nonlinear quantum optics mediated by Rydberg interactions

    NASA Astrophysics Data System (ADS)

    Firstenberg, O.; Adams, C. S.; Hofferberth, S.

    2016-08-01

    By mapping the strong interaction between Rydberg excitations in ultra-cold atomic ensembles onto single photons via electromagnetically induced transparency, it is now possible to realize a medium which exhibits a strong optical nonlinearity at the level of individual photons. We review the theoretical concepts and the experimental state-of-the-art of this exciting new field, and discuss first applications in the field of all-optical quantum information processing.

  6. Universal scaling in nonlinear optical molecules

    NASA Astrophysics Data System (ADS)

    Perez-Moreno, Javier

    2015-09-01

    In organic molecules, the strength of the linear and nonlinear optical response scales depends on the size of the structure. Power-laws that correlate the length of a structure and its nonlinear structure have been proposed by different researchers. These power-laws are described as function of the number of repeating units, and are derived from the experimental characterization of one set of homologue compounds. Typically, every set of homologues has been reported to obey a different power-law. We show how the sum rules allow to derive universal scaling power-laws that apply to all structures and are in agreement with the experimental data. Using the concept of universal scaling, we propose a classification of the scaling behavior that can be used to determine what are the best molecular paradigms for future nonlinear optical applications.

  7. Anomalous optical nonlinearity of dielectric nanodispersions

    NASA Astrophysics Data System (ADS)

    Milichko, V. A.; Dzyuba, V. P.; Kul'chin, Yurii N.

    2013-06-01

    We present the results of studying the nonlinear optical response of nanodispersions of semiconductor (TiO2, ZnO) and dielectric (SiO2, Al2O3) nanoparticles of spherical, spheroidal and flake shape, suspended in polar and nonpolar dielectric matrices (water, isopropanol, polymethylsiloxane and transformer oil) by means of z-scanning in the field of low-intensity visible laser radiation. It is found that, unlike semiconductor nanoparticles and particles of spherical shape, flake-shaped SiO2 and Al2O3 nanoparticles suspended in nonpolar matrices exhibit nonlinear optical response within the intensity interval from 0 to 500 W cm-2 that vanishes at higher intensities. The diagrams of energy states of the optical electrons in nanoparticles that allow explanation of differences in the nonlinear-optical properties of nanodispersions are proposed. Good agreement between the experimental and theoretical dependences of nonlinear refractive indices and absorption coefficients on the intensity of radiation is observed.

  8. Nonlinear optical studies of polymer interfaces

    SciTech Connect

    Shen, Y.R. |

    1993-11-01

    Second-order nonlinear optical processes can be used as effective surface probes. They can provide some unique opportunities for studies of polymer interfaces. Here the author describes two examples to illustrate the potential of the techniques. One is on the formation of metal/polymer interfaces. The other is on the alignment of liquid crystal films by mechanically rubbed polymer surfaces.

  9. Nonlinear optical cryptosystem resistant to standard and hybrid attacks

    NASA Astrophysics Data System (ADS)

    Sinha, Aloka

    2016-06-01

    We propose a nonlinear optical cryptosystem that is resistant to amplitude-phase retrieval attacks, known-plaintext attack and chosen-plaintext attack. A squaring operation is introduced in the encryption path, which thwarts the iterative attacks. This nonlinear operation tends to amplify the error in the estimation during an iterative attack. The decryption process requires the use of a square-root operation. Thus, in the reverse path also, the attacks encounter the nonlinear square-root operation. These two nonlinearities make the iterative attacks unstable, thereby leading to non-convergence of the mean square error (MSE). Our technique is also resistant to hybrid attacks. The technique is general and is shown to work on a variety of images of the type grayscale and binary. Numerical simulation results corroborate the effectiveness of the proposed cryptosystem.

  10. High field optical nonlinearities in gases

    NASA Astrophysics Data System (ADS)

    Cheng, Yu-Hsiang

    Optical femtosecond self-channeling in gases, also called femtosecond filamentation, has become an important area of research in high field nonlinear optics. Filamentation occurs when laser light self-focuses in a gas owing to self-induced nonlinearity, and then defocuses in the plasma generated by the self-focused beam. The result of this process repeating itself multiple times is an extended region of plasma formation. Filamentation studies have been motivated by the extremely broad range of applications, especially in air, including pulse compression, supercontinuum generation, broadband high power terahertz pulse generation, discharge triggering and guiding, and remote sensing. Despite the worldwide work in filamentation, the fundamental gas nonlinearities governing self-focusing had never been directly measured in the range of laser intensity up to and including the ionization threshold. This dissertation presents the first such measurements. We absolutely measured the temporal refractive index change of O2, N2, Ar, H2, D2 and N2O caused by highfield ultrashort optical pulses with single-shot supercontinuum spectral interferometry, cleanly separating for the first time the instantaneous electronic and delayed rotational nonlinear response in diatomic gases. We conclusively showed that a recent claim by several European groups that the optical bound electron nonlinearity saturates and goes negative is not correct. Such a phenomenon would preclude the need for plasma to provide the defocusing contribution for filamentation. Our results show that the 'standard model of filamentation', where the defocusing is provided by plasma, is correct. Finally, we demonstrated that high repetition rate femtosecond laser pulses filamenting in gases can generate long-lived gas density `holes' which persist on millisecond timescales, long after the plasma has recombined. Gas density decrements up to ~20% have been measured. The density hole refilling is dominated by thermal

  11. Nonlinear optical losses in medical fibers

    NASA Astrophysics Data System (ADS)

    Ozols, Andris O.; Ivanovs, Girts; Coders, Guntars

    1997-02-01

    Attenuation intensity dependences of 1064 nm and 532 nm picosecond pulses in multimode optical fibers produced for medical purposes by 'Anda' factory in Livani, Latvia are experimentally studied. A strong linear growth of inverse transmittance with intensity is found. The possible mechanism of nonlinear losses are analyzed and the conclusion is made that the observed effect is mainly due to the two-photon absorption involving defects levels. Strong attenuation intensity dependence can be used to make such fiber optical devices as light power limiters, optically driven light modulators and dynamic holographic frequency filters.

  12. Nonlinear light-matter interactions in engineered optical media

    NASA Astrophysics Data System (ADS)

    Litchinitser, Natalia

    In this talk, we consider fundamental optical phenomena at the interface of nonlinear and singular optics in artificial media, including theoretical and experimental studies of linear and nonlinear light-matter interactions of vector and singular optical beams in metamaterials. We show that unique optical properties of metamaterials open unlimited prospects to ``engineer'' light itself. Thanks to their ability to manipulate both electric and magnetic field components, metamaterials open new degrees of freedom for tailoring complex polarization states and orbital angular momentum (OAM) of light. We will discuss several approaches to structured light manipulation on the nanoscale using metal-dielectric, all-dielectric and hyperbolic metamaterials. These new functionalities, including polarization and OAM conversion, beam magnification and de-magnification, and sub-wavelength imaging using novel non-resonant hyperlens are likely to enable a new generation of on-chip or all-fiber structured light applications. The emergence of metamaterials also has a strong potential to enable a plethora of novel nonlinear light-matter interactions and even new nonlinear materials. In particular, nonlinear focusing and defocusing effects are of paramount importance for manipulation of the minimum focusing spot size of structured light beams necessary for nanoscale trapping, manipulation, and fundamental spectroscopic studies. Colloidal suspensions offer as a promising platform for engineering polarizibilities and realization of large and tunable nonlinearities. We will present our recent studies of the phenomenon of spatial modulational instability leading to laser beam filamentation in an engineered soft-matter nonlinear medium. Finally, we introduce so-called virtual hyperbolic metamaterials formed by an array of plasma channels in air as a result of self-focusing of an intense laser pulse, and show that such structure can be used to manipulate microwave beams in a free space. This

  13. Space Vehicle Pose Estimation via Optical Correlation and Nonlinear Estimation

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Herren, Kenneth

    2007-01-01

    A technique for 6-degree-of-freedom (6DOF) pose estimation of space vehicles is being developed. This technique draws upon recent developments in implementing optical correlation measurements in a nonlinear estimator, which relates the optical correlation measurements to the pose states (orientation and position). For the optical correlator, the use of both conjugate filters and binary, phase-only filters in the design of synthetic discriminant function (SDF) filters is explored. A static neural network is trained a priori and used as the nonlinear estimator. New commercial animation and image rendering software is exploited to design the SDF filters and to generate a large filter set with which to train the neural network. The technique is applied to pose estimation for rendezvous and docking of free-flying spacecraft and to terrestrial surface mobility systems for NASA's Vision for Space Exploration. Quantitative pose estimation performance will be reported. Advantages and disadvantages of the implementation of this technique are discussed.

  14. Space Vehicle Pose Estimation via Optical Correlation and Nonlinear Estimation

    NASA Technical Reports Server (NTRS)

    Rakoczy, John M.; Herren, Kenneth A.

    2008-01-01

    A technique for 6-degree-of-freedom (6DOF) pose estimation of space vehicles is being developed. This technique draws upon recent developments in implementing optical correlation measurements in a nonlinear estimator, which relates the optical correlation measurements to the pose states (orientation and position). For the optical correlator, the use of both conjugate filters and binary, phase-only filters in the design of synthetic discriminant function (SDF) filters is explored. A static neural network is trained a priori and used as the nonlinear estimator. New commercial animation and image rendering software is exploited to design the SDF filters and to generate a large filter set with which to train the neural network. The technique is applied to pose estimation for rendezvous and docking of free-flying spacecraft and to terrestrial surface mobility systems for NASA's Vision for Space Exploration. Quantitative pose estimation performance will be reported. Advantages and disadvantages of the implementation of this technique are discussed.

  15. Quantitative nonlinear optical assessment of atherosclerosis progression in rabbits.

    PubMed

    Mostaço-Guidolin, Leila B; Kohlenberg, Elicia K; Smith, Michael; Hewko, Mark; Major, Arkady; Sowa, Michael G; Ko, Alex C-T

    2014-07-01

    Quantification of atherosclerosis has been a challenging task owing to its complex pathology. In this study, we validated a quantitative approach for assessing atherosclerosis progression in a rabbit model using a numerical matrix, optical index for plaque burden, derived directly from the nonlinear optical microscopic images captured on the atherosclerosis-affected blood vessel. A positive correlation between this optical index and the severity of atherosclerotic lesions, represented by the age of the rabbits, was established based on data collected from 21 myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits with age ranging between new-born and 27 months old. The same optical index also accurately identified high-risk locations for atherosclerotic plaque formation along the entire aorta, which was validated by immunohistochemical fluorescence imaging. PMID:24892226

  16. Optical Analysis of Microscope Images

    NASA Astrophysics Data System (ADS)

    Biles, Jonathan R.

    Microscope images were analyzed with coherent and incoherent light using analog optical techniques. These techniques were found to be useful for analyzing large numbers of nonsymbolic, statistical microscope images. In the first part phase coherent transparencies having 20-100 human multiple myeloma nuclei were simultaneously photographed at 100 power magnification using high resolution holographic film developed to high contrast. An optical transform was obtained by focussing the laser onto each nuclear image and allowing the diffracted light to propagate onto a one dimensional photosensor array. This method reduced the data to the position of the first two intensity minima and the intensity of successive maxima. These values were utilized to estimate the four most important cancer detection clues of nuclear size, shape, darkness, and chromatin texture. In the second part, the geometric and holographic methods of phase incoherent optical processing were investigated for pattern recognition of real-time, diffuse microscope images. The theory and implementation of these processors was discussed in view of their mutual problems of dimness, image bias, and detector resolution. The dimness problem was solved by either using a holographic correlator or a speckle free laser microscope. The latter was built using a spinning tilted mirror which caused the speckle to change so quickly that it averaged out during the exposure. To solve the bias problem low image bias templates were generated by four techniques: microphotography of samples, creation of typical shapes by computer graphics editor, transmission holography of photoplates of samples, and by spatially coherent color image bias removal. The first of these templates was used to perform correlations with bacteria images. The aperture bias was successfully removed from the correlation with a video frame subtractor. To overcome the limited detector resolution it is necessary to discover some analog nonlinear intensity

  17. Nonlinear Optical Characterization of Membrane Protein Microcrystals and Nanocrystals.

    PubMed

    Newman, Justin A; Simpson, Garth J

    2016-01-01

    Nonlinear optical methods such as second harmonic generation (SHG) and two-photon excited UV fluorescence (TPE-UVF) imaging are promising approaches to address bottlenecks in the membrane protein structure determination pipeline. The general principles of SHG and TPE-UVF are discussed here along with instrument design considerations. Comparisons to conventional methods in high throughput crystallization condition screening and crystal quality assessment prior to X-ray diffraction are also discussed. PMID:27553237

  18. Nonlinear optical effects during femtosecond photodisruption

    NASA Astrophysics Data System (ADS)

    Poudel, Milan P.; Chen, Jinhai

    2009-11-01

    Several nonlinear effects (i.e., continuum generation, self-focusing, and material damage) were studied during femtosecond photodisruption. Numerical aperture dependence of white-light continuum generation and material damage were determined and a relation between the two effects was shown. We showed the possibility of reducing nonlinear side effects and at the same time ensuring precise cut by using lenses of a suitable numerical aperture for refractive surgery, cell surgery, and tissue dissection. Other side effects associated with optical breakdown in model substance were also discussed.

  19. Compressive optical imaging systems

    NASA Astrophysics Data System (ADS)

    Wu, Yuehao

    Compared to the classic Nyquist sampling theorem, Compressed Sensing or Compressive Sampling (CS) was proposed as a more efficient alternative for sampling sparse signals. In this dissertation, we discuss the implementation of the CS theory in building a variety of optical imaging systems. CS-based Imaging Systems (CSISs) exploit the sparsity of optical images in their transformed domains by imposing incoherent CS measurement patterns on them. The amplitudes and locations of sparse frequency components of optical images in their transformed domains can be reconstructed from the CS measurement results by solving an l1-regularized minimization problem. In this work, we review the theoretical background of the CS theory and present two hardware implementation schemes for CSISs, including a single pixel detector based scheme and an array detector based scheme. The first implementation scheme is suitable for acquiring Two-Dimensional (2D) spatial information of the imaging scene. We demonstrate the feasibility of this implementation scheme by developing a single pixel camera, a multispectral imaging system, and an optical sectioning microscope for fluorescence microscopy. The array detector based scheme is suitable for hyperspectral imaging applications, wherein both the spatial and spectral information of the imaging scene are of interest. We demonstrate the feasibility of this scheme by developing a Digital Micromirror Device-based Snapshot Spectral Imaging (DMD-SSI) system, which implements CS measurement processes on the Three-Dimensional (3D) spatial/spectral information of the imaging scene. Tens of spectral images can be reconstructed from the DMD-SSI system simultaneously without any mechanical or temporal scanning processes.

  20. Rigorous theory of molecular orientational nonlinear optics

    NASA Astrophysics Data System (ADS)

    Kwak, Chong Hoon; Kim, Gun Yeup

    2015-01-01

    Classical statistical mechanics of the molecular optics theory proposed by Buckingham [A. D. Buckingham and J. A. Pople, Proc. Phys. Soc. A 68, 905 (1955)] has been extended to describe the field induced molecular orientational polarization effects on nonlinear optics. In this paper, we present the generalized molecular orientational nonlinear optical processes (MONLO) through the calculation of the classical orientational averaging using the Boltzmann type time-averaged orientational interaction energy in the randomly oriented molecular system under the influence of applied electric fields. The focal points of the calculation are (1) the derivation of rigorous tensorial components of the effective molecular hyperpolarizabilities, (2) the molecular orientational polarizations and the electronic polarizations including the well-known third-order dc polarization, dc electric field induced Kerr effect (dc Kerr effect), optical Kerr effect (OKE), dc electric field induced second harmonic generation (EFISH), degenerate four wave mixing (DFWM) and third harmonic generation (THG). We also present some of the new predictive MONLO processes. For second-order MONLO, second-order optical rectification (SOR), Pockels effect and difference frequency generation (DFG) are described in terms of the anisotropic coefficients of first hyperpolarizability. And, for third-order MONLO, third-order optical rectification (TOR), dc electric field induced difference frequency generation (EFIDFG) and pump-probe transmission are presented.

  1. Rigorous theory of molecular orientational nonlinear optics

    SciTech Connect

    Kwak, Chong Hoon Kim, Gun Yeup

    2015-01-15

    Classical statistical mechanics of the molecular optics theory proposed by Buckingham [A. D. Buckingham and J. A. Pople, Proc. Phys. Soc. A 68, 905 (1955)] has been extended to describe the field induced molecular orientational polarization effects on nonlinear optics. In this paper, we present the generalized molecular orientational nonlinear optical processes (MONLO) through the calculation of the classical orientational averaging using the Boltzmann type time-averaged orientational interaction energy in the randomly oriented molecular system under the influence of applied electric fields. The focal points of the calculation are (1) the derivation of rigorous tensorial components of the effective molecular hyperpolarizabilities, (2) the molecular orientational polarizations and the electronic polarizations including the well-known third-order dc polarization, dc electric field induced Kerr effect (dc Kerr effect), optical Kerr effect (OKE), dc electric field induced second harmonic generation (EFISH), degenerate four wave mixing (DFWM) and third harmonic generation (THG). We also present some of the new predictive MONLO processes. For second-order MONLO, second-order optical rectification (SOR), Pockels effect and difference frequency generation (DFG) are described in terms of the anisotropic coefficients of first hyperpolarizability. And, for third-order MONLO, third-order optical rectification (TOR), dc electric field induced difference frequency generation (EFIDFG) and pump-probe transmission are presented.

  2. Nonlinearly enhanced sensing in coupled optical microresonators

    NASA Astrophysics Data System (ADS)

    Wang, Chao

    Optical microresonators that confine photons to micron dimensions with low loss at telecommunication wavelengths play an important role in building modern all-optical integrated circuit. Such systems attract a considerable amount of interest because of the compact size and easy fabrication with state-of-art technologies. One can use the microresonators as sensors, optical delay lines, filters, interferometers, and lasers. In this thesis, we investigate nonlinear effects for sensing application in microring resonators. We theoretically analyze the effect of the Kerr index, two-photon absorption, free-carrier absorption, and free-carrier dispersion. In particular, selfphase and cross-phase modulations caused by the Kerr index are shown to lead to a bifurcation of degenerate resonator mode intensities. Using coupled mode equations, we present the transmission properties of our resonator system with nonlinear effects included. New sensing mechanisms based on the nonlinear bistability and bifurcation are proposed to enhance the transmission's sensitivity to perturbations of the resonance frequency of the resonators. This is used to develop models of ultra-sensitive gyroscopes and refractive index sensors for detection of chemical analytes. The bifurcation dramatically enhances the Sagnac phase shift and therefore substantially lowers the minimum detectable rotation rate (< 1deg/hour) in a micro-resonator gyroscope. For index sensing, nonlinearities enhance the resonance frequency shift and a theoretical detection limit of 10-11 RIU is derived assuming common noises in micro-optical systems. In this work, we focus on silicon-on-insulator resonators but we also consider different platforms, including silicon oxynitride, Hydex, and chalcogenide glasses, and discuss the advantages of each. The results we show here highlight novel mechanisms that can be used in practical applications to improve the performance of a microresonator based optical sensor.

  3. Novel composites for nonlinear optics

    NASA Astrophysics Data System (ADS)

    Hameed-Muhammed, Muhammed Subhi

    A fully computerised Temperature-Gradient Zone-Melting (TGZM) apparatus was designed and built in order to produce novel and highly aligned composite films for Second Harmonic Generation (SHG). The TGZM apparatus consists of hot and cold aluminium blocks with glass- ceramic thermal insulator sandwiched between the two blocks. The composite films contain SHG-active guest crystals incorporated within a polymer matrix (host) forming a guest/host structure. These composites exhibit good optical performance in terms of SHG output (guest crystal), high mechanical strength, thermal and chemical stability (host polymer). These particular properties are of great importance especially for fibre-optical applications. 3-methyl-4-methoxy-4'-nitrostilbene (MMONS) is SHG-active guest material which was investigated by incorporating it in poly(methyl methacrylate) or PMMA(host polymer). Two PMMA molecular weight distributions (MWD) were used once at a time, in which the effect of that on the overall SHG intensity was clearly observed. It was found that a change of a polymer MWD does alter the output of the SHG signal. MMONS crystals were also embedded in another polymer host called Polystyrene (PS) in order to demonstrate the effect of using two different polymers on the SHG intensity of MMONS aligned films. The samples were cast on a glass slides and placed on the hot side of the TGZM apparatus (crystal growth from melt). Later they were drawn towards the cold side with a drawing rate closely matching the MMONS crystal growth rate and producing highly aligned composite films. A Nd:YAG laser beam (1064 nm) with 10 mJ fundamental energy was incident on the above samples (45° from the optic axis z) using type II phase matching, resulting in a green second harmonic signal of 532 nm. The refractive index mismatch between MMONS and a polymer host such as poly(9-vinyle carbazole) or PVK (used in this project) could cause a major light scattering (i.e light loss) during SHG intensity

  4. Second-order nonlinearity and optical image storage in phenyl-silica hybrid films doped with azo-dye chromophore using optical poling technique

    NASA Astrophysics Data System (ADS)

    Matsuoka, Nobuaki; Kitaoka, Kenji; Si, Jinhai; Fujita, Koji; Hirao, Kazuyuki

    2000-11-01

    4-[ N-ethyl- N-(2-hydroxyethyl)]amino-4 '-nitro-azobenzene (DR1)-doped phenyl group substituted silica films were prepared by a sol-gel method. The films were optically poled by the coherent superposition of 1064 and 532 nm beams from a Q-switched Nd:YAG laser. To discuss the effects of the modifier group, interaction between DR1 molecules and the matrix was investigated. The delocalization of π electrons occurred between DR1 molecules and the phenyl-silica hybrid matrix, and that consequently the polarized DR1 molecules could be stabilized. By use of the optimized optical poling technique, optical storage was successfully demonstrated for a phenyl-silica hybrid film doped with DR1.

  5. Nonlinear Mixing in Optical Multicarrier Systems

    NASA Astrophysics Data System (ADS)

    Hameed, Mahmood Abdul

    Although optical fiber has a vast spectral bandwidth, efficient use of this bandwidth is still important in order to meet the ever increased capacity demand of optical networks. In addition to wavelength division multiplexing, it is possible to partition multiple low-rate subcarriers into each high speed wavelength channel. Multicarrier systems not only ensure efficient use of optical and electrical components, but also tolerate transmission impairments. The purpose of this research is to understand the impact of mixing among subcarriers in Radio-Over-Fiber (RoF) and high speed optical transmission systems, and experimentally demonstrate techniques to minimize this impact. We also analyze impact of clipping and quantization on multicarrier signals and compare bandwidth efficiency of two popular multiplexing techniques, namely, orthogonal frequency division multiplexing (OFDM) and Nyquist modulation. For an OFDM-RoF system, we present a novel technique that minimizes the RF domain signal-signal beat interference (SSBI), relaxes the phase noise limit on the RF carrier, realizes the full potential of optical heterodyne-based RF carrier generation, and increases the performance-to-cost ratio of RoF systems. We demonstrate a RoF network that shares the same RF carrier for both downlink and uplink, avoiding the need of an additional RF oscillator in the customer unit. For multi-carrier optical transmission, we first experimentally compare performance degradations of coherent optical OFDM and single-carrier Nyquist pulse modulated systems in a nonlinear environment. We then experimentally evaluate SSBI compensation techniques in the presence of semiconductor optical amplifier (SOA) induced nonlinearities for a multicarrier optical system with direct detection. We show that SSBI contamination can be significantly reduced from the data signal when the carrier-to-signal power ratio is sufficiently low.

  6. Application of Novel Nonlinear Optical Materials to Optical Processing

    NASA Technical Reports Server (NTRS)

    Banerjee, Partha P.

    1999-01-01

    We describe wave mixing and interactions in nonlinear photorefractive polymers and disodium flourescein. Higher diffracted orders yielding forward phase conjugation can be generated in a two-wave mixing geometry in photorefractive polymers, and this higher order can be used for image edge enhancement and correlation. Four-wave mixing and phase conjugation is studied using nonlinear disodium floureschein, and the nature and properties of gratings written in this material are investigated.

  7. Nonlinear optical properties of multipyrrole dyes

    PubMed Central

    Frenette, Mathieu; Hatamimoslehabadi, Maryam; Bellinger-Buckley, Stephanie; Laoui, Samir; Bag, Seema; Dantiste, Olivier; Rochford, Jonathan; Yelleswarapu, Chandra

    2014-01-01

    The nonlinear optical properties of a series of pyrrolic compounds consisting of BODIPY and aza-BODIPY systems are investigated using 532 nm nanosecond laser and the Z-scan technique. Results show that 3,5-distyryl extension of BODIPY to the red shifted MeO2BODIPY dye has a dramatic impact on its nonlinear absorption properties changing it from a saturable absorber to an efficient reverse saturable absorbing material with a nonlinear absorption coefficient of 4.64 × 10−10 m/W. When plotted on a concentration scale per mole of dye in solution MeO2BODIPY far outperforms the recognized zinc(II) phthalocyanine dye and is comparable to that of zinc(II) tetraphenylporphyrin. PMID:25242819

  8. Highly nonlinear layered spiral microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Rodrigues, Sílvia M.; Facão, Margarida M.; Latas, Sofia C.; Ferreira, Mário F.

    2013-08-01

    A layered spiral microstructured optical fiber (LS-MOF) is presented, which offers the possibility of a good control of both the dispersion and the nonlinear properties. The proposed design is analyzed using a finite element method considering silica and air as the materials. Zero dispersion, low confinement loss, and a record value of γ = 70.0 W-1/km for the LS-MOF nonlinear parameter are simultaneously obtained at 1.55 μm, whereas a higher value γ = 169.4 W-1/km can be achieved at 1.06 μm. Our results demonstrate the great potential of the LS-MOF for several nonlinear applications, namely for an efficient generation of the supercontinuum.

  9. Ferroelectric optical image comparator

    DOEpatents

    Butler, M.A.; Land, C.E.; Martin, S.J.; Pfeifer, K.B.

    1993-11-30

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image. 7 figures.

  10. Ferroelectric optical image comparator

    DOEpatents

    Butler, Michael A.; Land, Cecil E.; Martin, Stephen J.; Pfeifer, Kent B.

    1993-01-01

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image.

  11. Nonlinear optics of astaxanthin thin films

    NASA Astrophysics Data System (ADS)

    Esser, A.; Fisch, Herbert; Haas, Karl-Heinz; Haedicke, E.; Paust, J.; Schrof, Wolfgang; Ticktin, Anton

    1993-02-01

    Carotinoids exhibit large nonlinear optical properties due to their extended (pi) -electron system. Compared to other polyenes which show a broad distribution of conjugation lengths, carotinoids exhibit a well defined molecular structure, i.e. a well defined conjugation length. Therefore the carotinoid molecules can serve as model compounds to study the relationship between structure and nonlinear optical properties. In this paper the synthesis of four astaxanthins with C-numbers ranging from 30 to 60, their preparation into thin films, wavelength dispersive Third Harmonic Generation (THG) measurements and some molecular modelling calculations will be presented. Resonant (chi) (3) values reach 1.2(DOT)10-10 esu for C60 astaxanthin. In the nonresonant regime a figure of merit (chi) (3)/(alpha) of several 10-13 esu-cm is demonstrated.

  12. Nonlinear optical studies of organic monolayers

    SciTech Connect

    Shen, Y.R.

    1988-02-01

    Second-order nonlinear optical effects are forbidden in a medium with inversion symmetry, but are necessarily allowed at a surface where the inversion summary is broken. They are often sufficiently strong so that a submonolayer perturbation of the surface can be readily detected. They can therefore be used as effective tools to study monolayers adsorbed at various interfaces. We discuss here a number of recent experiments in which optical second harmonic generation (SHG) and sum-frequency generation (SFG) are employed to probe and characterize organic monolayers. 15 refs., 5 figs.

  13. Optical Frequency Domain Imaging

    NASA Astrophysics Data System (ADS)

    Bouma, Brett E.; Tearney, Guillermo J.; Vakoc, Benjamin; Yun, Seok Hyun

    In this chapter, we discuss a frequency-domain approach, optical frequency-domain imaging (OFDI), which is based on optical frequency-domain reflectometry and uses a wavelength-swept laser and standard single-element photodetectors. The chapter begins with an overview of the fundamental aspects of the technology, including the detected signal, sensitivity, depth range, and resolution, and then goes on to discuss specific component technologies including the light source, interferometer and acquisition electronics, and image processing. The final section of the chapter provides a brief glimpse at some of the biomedical applications that most directly take advantage of the improved speed and sensitivity of OFDI.

  14. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1993-10-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  15. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsoodi, S.; Pang, Y.

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6]/hv.

  16. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, T.J.; Ijadi-Maghsooodi, S; Yi Pang.

    1993-10-19

    A polymeric material is described which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl[sub 5] or W(CO)[sub 6].

  17. Third-order optical nonlinearity of chlorophenols

    NASA Astrophysics Data System (ADS)

    Maloney, C.; Blau, W.

    1988-02-01

    Degenerate four-wave mixing of infrared (1.064 μm) pulses with 130 ps duration was studied in o-, p- and m- chlorophenols. Nonlinear susceptibilities χ (3) of (5.5-6.0) × 10 -20 m 2/V 2 were measured. By temporally delaying the incidence of the second pump pulse contributions from an optical Kerr effect and an electrostrictive effect are observed.

  18. Nonlinear optical and conductive polymeric material

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1992-05-19

    A polymeric material which exhibits nonlinear optical properties if undoped and conductive properties if doped. The polymer is prepared by polymerizing diethynylsilane compositions, the resulting polymeric material having a weight average molecular weight between about 20,000 and about 200,000 grams per mole. The polymer is prepared and catalytically polymerized by exposure to a catalyst, such as MoCl.sub.5 or W(CO).sub.6 /hv.

  19. Laboratory Studies of Nonlinear Optical Signals for Caries Detection.

    PubMed

    Terrer, E; Panayotov, I V; Slimani, A; Tardivo, D; Gillet, D; Levallois, B; Fejerskov, O; Gergely, C; Cuisinier, F J G; Tassery, H; Cloitre, T

    2016-05-01

    Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis. PMID:26826107

  20. Single-Photon Nonlinear Optics with Graphene Plasmons

    NASA Astrophysics Data System (ADS)

    Gullans, M.; Chang, D. E.; Koppens, F. H. L.; de Abajo, F. J. García; Lukin, M. D.

    2013-12-01

    We show that it is possible to realize significant nonlinear optical interactions at the few photon level in graphene nanostructures. Our approach takes advantage of the electric field enhancement associated with the strong confinement of graphene plasmons and the large intrinsic nonlinearity of graphene. Such a system could provide a powerful platform for quantum nonlinear optical control of light. As an example, we consider an integrated optical device that exploits this large nonlinearity to realize a single photon switch.

  1. Nonlinear Optical Properties of Triphenylalanine-based Peptide Nanostructures

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, A. V.; Mishina, E. D.; Sigov, A. S.

    2016-05-01

    Nonlinear optical properties of peptide nanobelts and peptide nanospheres, the two types of self-assembled triphenylalanine-based peptide nanostructures, are studied. Nanobelts nonlinear susceptibility tensor components are evaluated, and nanobelts crystal structure and crystallographic orientation are defined on the basis of nonlinear optical mapping and polarization dependences of the second harmonic signal. The results obtained suggest that it is possible to use these materials as biologically compatible nonlinear optical converters.

  2. Integrated optical devices using bacteriorhodopsin as active nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Dér, András; Fábián, László; Valkai, Sándor; Wolff, Elmar; Ramsden, Jeremy; Ormos, Pál

    2006-08-01

    Coupling of optical data-processing devices with microelectronics, telecocommunication and sensory functions, is among the biggest challenges in molecular electronics. Intensive research is going on to find suitable nonlinear optical materials that could meet the demanding requirements of optoelectronic applications, especially regarding high sensitivity and stability. In addition to inorganic and organic crystals, biological molecules have also been considered for use in integrated optics, among which the bacterial chromoprotein, bacteriorhodopsin (bR) generated the most interest. bR undergoes enormous absorption and concomitant refractive index changes upon initiation of a cyclic series of photoreactions by a burst of actinic light. This effect can be exploited to create highly versatile all-optical logical elements. We demonstrate the potential of this approach by investigating the static and dynamic response of several basic elements of integrated optical devices. Our results show that, due to its relatively high refractive index changes, bR can be used as an active nonlinear optical material to produce a variety of integrated optical switching and modulation effects.

  3. Real-time optical image processing techniques

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1988-01-01

    Nonlinear real-time optical processing on spatial pulse frequency modulation has been pursued through the analysis, design, and fabrication of pulse frequency modulated halftone screens and the modification of micro-channel spatial light modulators (MSLMs). Micro-channel spatial light modulators are modified via the Fabry-Perot method to achieve the high gamma operation required for non-linear operation. Real-time nonlinear processing was performed using the halftone screen and MSLM. The experiments showed the effectiveness of the thresholding and also showed the needs of higher SBP for image processing. The Hughes LCLV has been characterized and found to yield high gamma (about 1.7) when operated in low frequency and low bias mode. Cascading of two LCLVs should also provide enough gamma for nonlinear processing. In this case, the SBP of the LCLV is sufficient but the uniformity of the LCLV needs improvement. These include image correlation, computer generation of holograms, pseudo-color image encoding for image enhancement, and associative-retrieval in neural processing. The discovery of the only known optical method for dynamic range compression of an input image in real-time by using GaAs photorefractive crystals is reported. Finally, a new architecture for non-linear multiple sensory, neural processing has been suggested.

  4. Non-linear Post Processing Image Enhancement

    NASA Technical Reports Server (NTRS)

    Hunt, Shawn; Lopez, Alex; Torres, Angel

    1997-01-01

    A non-linear filter for image post processing based on the feedforward Neural Network topology is presented. This study was undertaken to investigate the usefulness of "smart" filters in image post processing. The filter has shown to be useful in recovering high frequencies, such as those lost during the JPEG compression-decompression process. The filtered images have a higher signal to noise ratio, and a higher perceived image quality. Simulation studies comparing the proposed filter with the optimum mean square non-linear filter, showing examples of the high frequency recovery, and the statistical properties of the filter are given,

  5. Nonlinear Optical Properties and Applications of Polydiacetylene

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Paley, Mark S.; Witherow, William K.; Frazier, Donald O.

    2000-01-01

    Recently, we have demonstrated a picosecond all-optical switch, which also functions as a partial all-optical NAND logic gate using a novel polydiacetylene that is synthesized in our laboratory. The nonlinear optical properties of the polydiacetylene material are measured using the Z-scan technique. A theoretical model based on a three level system is investigated and the rate equations of the system are solved. The theoretical calculations are proven to match nicely with the experimental results. The absorption cross-sections for both the first and higher excited states are estimated. The analyses also show that the material suffers a photochemical change beyond a certain level of the laser power and its physical properties suffer radical changes. These changes are the cause for the partial NAND gate function and the switching mechanism.

  6. Linear and nonlinear optical absorption coefficients of spherical dome shells

    NASA Astrophysics Data System (ADS)

    Guo, Kangxian; Liu, Guanghui; Huang, Lu; Zheng, Xianyi

    2015-08-01

    Linear and nonlinear optical absorption coefficients of spherical dome shells are theoretically investigated within analytical wave functions and numerical quantized energy levels. Our results show that the inner radius, the outer radius and the cut-off angle of spherical dome shells have great influences on linear and nonlinear optical absorption coefficients as well as the total optical absorption coefficients. It is found that with the increase of the inner radius and the outer radius, linear and nonlinear optical absorption coefficients exhibit a blueshift and a redshift, respectively. However, with the increase of the cut-off angle, linear and nonlinear optical absorption coefficients do not shift. Besides, the resonant peaks of linear and nonlinear optical absorption coefficients climb up and then decrease with increasing the cut-off angle. The influences of the incident optical intensity on the total optical absorption coefficients are studied. It is found that the bleaching effect occurs at higher incident optical intensity.

  7. Holography Experiments on Optical Imaging.

    ERIC Educational Resources Information Center

    Bonczak, B.; Dabrowski, J.

    1979-01-01

    Describes experiments intended to produce a better understanding of the holographic method of producing images and optical imaging by other optical systems. Application of holography to teaching physics courses is considered. (Author/SA)

  8. Thermal optical nonlinearity enhanced by gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Souza, Rogério F.; Alencar, Márcio A. R. C.; Nascimento, César M.; da Silva, Monique G. A.; Meneghetti, Mario R.; Hickmann, Jandir M.

    2006-08-01

    We report on the observation of a large thermal nonlinearity of an organic material enhanced by the presence of gold nanoparticles. The studied system consisted of a colloid of castor oil and gold particles with average diameter of 10 nm, with filling factor of 4.0x10 -5. Z-scan measurements were performed for an excitation wavelength tuned at 810 nm in the CW regime. It was observed that this colloidal system presents a large thermal nonlinear refractive index, which was equal to -7.4x10 -8 cm2/W. This value is about 41 times larger than the n II of the host material. The thermo-optic coefficient of the colloid was also evaluated, and a large enhancement was observed in its value owing to the presence of the gold nanoparticles in the organic material.

  9. Nonlinear methods for distributed optical fiber sensing

    NASA Astrophysics Data System (ADS)

    Rogers, Alan J.; Handerek, Vincent A.

    1994-11-01

    Distributed optical-fiber sensing (DOFS) utilizes the unique advantages of the optical fiber as a passive, dielectric, flexible and one- dimensional measurement medium. It offers full spatial and temporal information concerning the behavior of a large range of measurand fields. Among the many potential application areas of DOFS are those in aerospace, petrochemicals, electricity supply, mining and civil engineering. Methods for realizing DOFS have hitherto concentrated on linear backscatter techniques in the fiber. New explorations to be described in this paper give the emphasis to nonlinear, forward-scatter techniques, and especially to two of these which rely on the optical Kerr effect. The primary advantage of this approach is a significantly improved spatial resolution, down to approximately equals 0.1. m. A description also will be given of a promising quasi-distributed (forward-scatter or backscatter) arrangement which used the (nonlinear) photosensitivity of fibers to devise a DOFS system for simultaneous quasi-distributed measurement of strain and temperature. Prospects for the future of DOFS technology will be reviewed.

  10. Optical imaging in cognitive neuroscience

    NASA Astrophysics Data System (ADS)

    Luo, Qingming; Zeng, Shaoqun; Gong, Hui

    2002-04-01

    Cognitive neuroscience is a science of information processing. Optical techniques are playing more and more important roles in revealing the mechanisms of information processing from different levels of the nervous system. This paper gives an overview of the optical imaging approaches in cognitive neuroscience in our lab. First we introduce optical imaging of neurons with multiphoton excitation laser scanning confocal microscopy, then optical imaging of either cultured neuronal networks or nature neuronal networks with multiphoton microscopic imaging system combined with multi- electrode array, and then several optical imaging systems for intrinsic signal imaging in cortex or brain slices, which include CCD-based optical imaging system, OCT system and laser speckle imaging system. Finally we report our recent results on functional optical imaging of human brain activity.

  11. Ferroelectric optical image comparator

    SciTech Connect

    Butler, M.A.; Land, C.E.; Martin, S.J.; Pfeifer, K.B.

    1989-08-30

    The property of ferroelectric ceramics such as lead lanthanum zirconate titanate (PLZT) to store information has been known for many years. This relates to the property of ferroelectric ceramic materials to become permanently polarized when an electric signal is applied to the material. A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image. 5 figs.

  12. Enhanced optical phase conjugation in nonlinear metamaterials.

    PubMed

    Kim, Kihong

    2014-12-15

    Optical phase conjugation by degenerate four-wave mixing in nonlinear metamaterials is studied theoretically by solving the coupled wave equations using a generalized version of the invariant imbedding method. The phase-conjugate reflectance and the lateral shift of the phase-conjugate reflected beams are calculated and their dependencies on the frequency, the polarization, the incident angle, the material properties and the structure are investigated in detail. It is found that the efficiency of phase conjugation can be significantly enhanced due to the enhancement of electromagnetic fields in various metamaterial structures. PMID:25607488

  13. Nonlinear harmonic generation in distributed optical klystrons

    SciTech Connect

    H.P. Freund; George R. Neil

    2001-12-01

    A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5{angstrom} fundamental and a 1.5{angstrom} harmonic is discussed.

  14. Nonlinear optical microscopy improvement by focal-point axial modulation

    NASA Astrophysics Data System (ADS)

    Dashtabi, Mahdi Mozdoor; Massudi, Reza

    2016-05-01

    Among the most important challenges of microscopy-even more important than the resolution enhancement, especially in biological and neuroscience applications-is noninvasive and label-free imaging deeper into live scattering samples. However, the fundamental limitation on imaging depth is the signal-to-background ratio in scattering biological tissues. Here, using a vibrating microscope objective in conjunction with a lock-in amplifier, we demonstrate the background cancellation in imaging the samples surrounded by turbid and scattering media, which leads to more clear images deeper into the samples. Furthermore, this technique offers the localization and resolution enhancement as well as resolves ambiguities in signal interpretation, using a single-color laser. This technique is applicable to most nonlinear as well as some linear point-scanning optical microscopies.

  15. 2D wave-front shaping in optical superlattices using nonlinear volume holography.

    PubMed

    Yang, Bo; Hong, Xu-Hao; Lu, Rong-Er; Yue, Yang-Yang; Zhang, Chao; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-07-01

    Nonlinear volume holography is employed to realize arbitrary wave-front shaping during nonlinear processes with properly designed 2D optical superlattices. The concept of a nonlinear polarization wave in nonlinear volume holography is investigated. The holographic imaging of irregular patterns was performed using 2D LiTaO3 crystals with fundamental wave propagating along the spontaneous polarization direction, and the results agree well with the theoretical predictions. This Letter not only extends the application area of optical superlattices, but also offers an efficient method for wave-front shaping technology. PMID:27367067

  16. Some aspects of the comparison between optics and nonlinear acoustics

    NASA Technical Reports Server (NTRS)

    Perrin, B.

    1980-01-01

    Some results concerning nonlinear acoustics deduced from a comparison of nonlinear processes in optics and acoustics are discussed. An aspect of nonlinearity in acoustics connected with the dimensionality of the medium of propagation is emphasized and illustrated by the proof of static instability of an ideal linear solid. In addition a phenomenon, which can be called acoustical rectification by analogy with nonlinear optics, is propounded to measure the third order elastic constants. Its experimental consequences are predicted in a particular case.

  17. Boosted X Waves in Nonlinear Optical Systems

    SciTech Connect

    Arevalo, Edward

    2010-01-15

    X waves are spatiotemporal optical waves with intriguing superluminal and subluminal characteristics. Here we theoretically show that for a given initial carrier frequency of the system localized waves with genuine superluminal or subluminal group velocity can emerge from initial X waves in nonlinear optical systems with normal group velocity dispersion. Moreover, we show that this temporal behavior depends on the wave detuning from the carrier frequency of the system and not on the particular X-wave biconical form. A spatial counterpart of this behavior is also found when initial X waves are boosted in the plane transverse to the direction of propagation, so a fully spatiotemporal motion of localized waves can be observed.

  18. Femtosecond nonlinear optical properties of carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Dan; Liu, Ye; Yang, Heqing; Qian, Shixiong

    2002-09-01

    The nonlinear optical properties and ultrafast electron-relaxation dynamics of carbon nanoparticles were investigated by using the femtosecond optical Kerr effect and pump-probe techniques. The blueshift of the absorption edge with the decrease of the size of the nanoparticles reveals the opening of the gap. The magnitude of chi(3) for carbon nanoparticles is calculated to be 8.3 x10-13 esu, which arises from the contribution of delocalized feature of the pi electrons. The decay of photobleaching includes a fast and a slow component, which are assigned to the relaxation of the free carriers and trapped carriers, respectively. It is found that the lifetimes of two components of bleaching decrease as temperature of heat treatment is increased.

  19. Superresolution imaging from nonlinear inverse scattering

    NASA Astrophysics Data System (ADS)

    Ritter, R. Shane; Fiddy, M. A.

    2015-09-01

    Inverse scattering algorithms typically rely on weak scattering approximations and the inversion of far field data on an Ewald sphere. This, in turn, fixes the resolution of the computed image. However, it has long been observed that when multiple scattering occurs in a strongly interacting object, and a nonlinear inversion method is employed to image it, the resulting image can reveal subwavelength resolution. We have observed this phenomenon using a cepstral filtering approach and characterize it more fully here.

  20. Instrumentation in Diffuse Optical Imaging

    PubMed Central

    Zhang, Xiaofeng

    2014-01-01

    Diffuse optical imaging is highly versatile and has a very broad range of applications in biology and medicine. It covers diffuse optical tomography, fluorescence diffuse optical tomography, bioluminescence, and a number of other new imaging methods. These methods of diffuse optical imaging have diversified instrument configurations but share the same core physical principle – light propagation in highly diffusive media, i.e., the biological tissue. In this review, the author summarizes the latest development in instrumentation and methodology available to diffuse optical imaging in terms of system architecture, light source, photo-detection, spectral separation, signal modulation, and lastly imaging contrast. PMID:24860804

  1. Nonlinear Susceptibility Magnitude Imaging of Magnetic Nanoparticles

    PubMed Central

    Ficko, Bradley W.; Giacometti, Paolo; Diamond, Solomon G.

    2014-01-01

    This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R2 = 0.99, CNR = 84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R2 > 0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI. PMID:25505816

  2. The Quest for the Ultimate Nonlinear Optical Material

    NASA Astrophysics Data System (ADS)

    Dagenais, M.

    1990-10-01

    The following sections are included: * Introduction * From Infancy to the Real World * Highly Efficient Nonlinear Optical Materials for Switching and Processing * The Era of Pragmatism * Conclusion * References

  3. Cornea microstructure and mechanical responses measured with nonlinear optical and optical coherence microscopy using sub-10-fs pulses

    PubMed Central

    Wu, Qiaofeng; Applegate, Brian E.; Yeh, Alvin T.

    2011-01-01

    A combined nonlinear optical microscopy (NLOM) and optical coherence microscopy (OCM) imaging system has been assembled in order to simultaneously capture co-registered volumetric images of corneal morphology and biochemistry. Tracking of cell nuclei visible in the OCM volume enabled the calculation of strain depth profile in response to changes in intraocular pressure for rabbit cornea stroma. Results revealed nonlinear responses with a depth dependent strain distribution, exhibiting smaller strains in the anterior and larger strains in the posterior stroma. Cross-sectional images of collagen lamellae, visible in NLOM, showed inhomogeneous collagen structure along the anterior-posterior direction that correlated well with the noted heterogeneous corneal mechanical responses. PMID:21559126

  4. Nonlinear Optics in Novel Polymer Systems.

    NASA Astrophysics Data System (ADS)

    Li, Lian

    Polymeric nonlinear optical (NLO) materials have recently attracted considerable attention and been the subject of intensive investigations. Polymeric NLO materials possessing large second and third order NLO properties, ultrafast response times, high optical damage threshold, transparency over a broad wavelength range, and capability to be easily processed into good optical quality thin films, offer significant advantages over the traditional inorganic materials for applications in fabricating integrated optical devices, such as waveguide electro-optic (EO) modulators and optical frequency doublers, and optical signal processing devices. This dissertation presents the experimental investigations on novel NLO polymers synthesized in the Laboratory of Electronic and Photonic Materials at University of Massachusetts Lowell. Progress made for the past few years on polymeric NLO materials is reviewed, especially with regard to the second order NLO properties of the polymeric materials. Two novel stable second order NLO polymer systems, an interpenetrating polymer network (IPN) formed via thermal crosslinking and a sol-gel process, and a photocrosslinkable conducting polymer, upon poling and crosslinking, exhibited large and stable second order NLO properties measured for these polymers by using the second harmonic generation (SHG) technique. For the IPN system, the SHG measurements as a function of time at several elevated temperatures indicate the superb stability of the second order NLO properties. For the conducting NLO polymer, the NLO property of the poled and photocrosslinked polymer film is stable at room temperature. The wavelength shifting of a Q-switched Nd:YAG laser by stimulated Raman scattering is also described. Measurements were made on the third order NLO properties of a dye doped photocrosslinkable guest-host polymer system at different dye concentrations with a modified Michelson interferometer. By functionalizing the dye to make it more compatible to

  5. Nonlinear Optical Microscopy Signal Processing Strategies in Cancer

    PubMed Central

    Adur, Javier; Carvalho, Hernandes F; Cesar, Carlos L; Casco, Víctor H

    2014-01-01

    This work reviews the most relevant present-day processing methods used to improve the accuracy of multimodal nonlinear images in the detection of epithelial cancer and the supporting stroma. Special emphasis has been placed on methods of non linear optical (NLO) microscopy image processing such as: second harmonic to autofluorescence ageing index of dermis (SAAID), tumor-associated collagen signatures (TACS), fast Fourier transform (FFT) analysis, and gray level co-occurrence matrix (GLCM)-based methods. These strategies are presented as a set of potential valuable diagnostic tools for early cancer detection. It may be proposed that the combination of NLO microscopy and informatics based image analysis approaches described in this review (all carried out on free software) may represent a powerful tool to investigate collagen organization and remodeling of extracellular matrix in carcinogenesis processes. PMID:24737930

  6. Nonlinear Optical Interactions in Plasmas at JILA

    NASA Astrophysics Data System (ADS)

    Dollar, F.; Hickstein, D. D.; Popmintchev, D.; Becker, A.; Ellis, J.; Hernandez-Garcia, C.; Jaron-Becker, A.; Popmintchev, T.; Xiong, W.; Murnane, M. M.; Kapteyn, H. C.; Dukovic, G.; Jimenez, J.; Palm, B.; Schnitzenbaumer, K.; Perez-Hernandez, J.; Gaeta, A.; Gao, X.; Shim, B.; Plaja, L.; Levis, R.; Tarazkar, M.; Foord, M. E.; Gaffney, J. A.; Libby, S. B.

    2014-10-01

    We present data from two recent experiments. First, we demonstrate direct observations of localized light absorption in a single nanoparticle irradiated by a strong femtosecond laser field. By imaging the photoion momentum distribution resulting from plasma formation in a laser-irradiated nanostructure, we map the spatial location of the highly localized plasma and thereby image the nanoscale light absorption. Secondly, we show the high linear and nonlinear UV refractive indices of both neutral atoms and ions compensate for plasma dispersion, even in multiply-ionized gases. The experimental work was primarily funded by DOE Grant Number: DE-SC0008803, the DARPA PULSE program, and ARO W911NF-12-1-0436.

  7. Ultrafast and nonlinear optics in carbon nanomaterials.

    PubMed

    Kono, Junichiro

    2013-02-01

    Carbon-based nanomaterials—single-wall carbon nanotubes (SWCNTs) and graphene, in particular—have emerged in the last decade as novel low-dimensional systems with extraordinary properties. Because they are direct-bandgap systems, SWCNTs are one of the leading candidates to unify electronic and optical functions in nanoscale circuitry; their diameter-dependent bandgaps can be utilized for multi-wavelength devices. Graphene's ultrahigh carrier mobilities are promising for high-frequency electronic devices, while, at the same time, it is predicted to have ideal properties for terahertz generation and detection due to its unique zero-gap, zero-mass band structure. There have been a large number of basic optical studies on these materials, but most of them were performed in the weak-excitation, quasi-equilibrium regime. In order to probe and assess their performance characteristics as optoelectronic materials under device-operating conditions, it is crucial to strongly drive them and examine their optical properties in highly non-equilibrium situations and with ultrashot time resolution. In this section, the reader will find the latest results in this rapidly growing field of research. We have assembled contributions from some of the leading experts in ultrafast and nonlinear optical spectroscopy of carbon-based nanomaterials. Specific topics featured include: thermalization, cooling, and recombination dynamics of photo-generated carriers; stimulated emission, gain, and amplification; ultrafast photoluminescence; coherent phonon dynamics; exciton–phonon and exciton–plasmon interactions; exciton–exciton annihilation and Auger processes; spontaneous and stimulated emission of terahertz radiation; four-wave mixing and harmonic generation; ultrafast photocurrents; the AC Stark and Franz–Keldysh effects; and non-perturbative light–mater coupling. We would like to express our sincere thanks to those who contributed their latest results to this special section

  8. Preparation of polymeric diacetylene thin films for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Frazier, Donald O. (Inventor); Mcmanus, Samuel P. (Inventor); Paley, Mark S. (Inventor); Donovan, David N. (Inventor)

    1995-01-01

    A method for producing polymeric diacetylene thin films having desirable nonlinear optical characteristics has been achieved by producing amorphous diacetylene polymeric films by simultaneous polymerization of diacetylene monomers in solution and deposition of polymerized diacetylenes on to the surface of a transparent substrate through which ultraviolet light has been transmitted. These amorphous polydiacetylene films produced by photo-deposition from solution possess very high optical quality and exhibit large third order nonlinear optical susceptibilities, such properties being suitable for nonlinear optical devices such as waveguides and integrated optics.

  9. Gregorian optical system with non-linear optical technology for protection against intense optical transients

    DOEpatents

    Ackermann, Mark R.; Diels, Jean-Claude M.

    2007-06-26

    An optical system comprising a concave primary mirror reflects light through an intermediate focus to a secondary mirror. The secondary mirror re-focuses the image to a final image plane. Optical limiter material is placed near the intermediate focus to optically limit the intensity of light so that downstream components of the optical system are protected from intense optical transients. Additional lenses before and/or after the intermediate focus correct optical aberrations.

  10. Nonlinear Optical Properties of Carotenoid and Chlorophyll Harmonophores

    NASA Astrophysics Data System (ADS)

    Tokarz, Danielle Barbara

    Information regarding the structure and function of living tissues and cells is instrumental to the advancement of cell biology and biophysics. Nonlinear optical microscopy can provide such information, but only certain biological structures generate nonlinear optical signals. Therefore, structural specificity can be achieved by introducing labels for nonlinear optical microscopy. Few studies exist in the literature about labels that facilitate harmonic generation, coined "harmonophores". This thesis consists of the first major investigation of harmonophores for third harmonic generation (THG) microscopy. Carotenoids and chlorophylls were investigated as potential harmonophores. Their nonlinear optical properties were studied by the THG ratio technique. In addition, a tunable refractometer was built in order to determine their second hyperpolarizability (gamma). At 830 nm excitation wavelength, carotenoids and chlorophylls were found to have large negative gamma values however, at 1028 nm, the sign of gamma reversed for carotenoids and remained negative for chlorophylls. Consequently, at 1028 nm wavelength, THG signal is canceled with mixtures of carotenoids and chlorophylls. Furthermore, when such molecules are covalently bonded as dyads or interact within photosynthetic pigment-protein complexes, it is found that additive effects with the gamma values still play a role, however, the overall gamma value is also influenced by the intra-pigment and inter-pigment interaction. The nonlinear optical properties of aggregates containing chlorophylls and carotenoids were the target of subsequent investigations. Carotenoid aggregates were imaged with polarization-dependent second harmonic generation and THG microscopy. Both techniques revealed crystallographic information pertaining to H and J aggregates and beta-carotene crystalline aggregates found in orange carrot. In order to demonstrate THG enhancement due to labeling, cultured cells were labeled with carotenoid

  11. Nonlinear optical magnetometry with accessible in situ optical squeezing

    SciTech Connect

    Otterstrom, N.; Pooser, R. C.; Lawrie, B. J.

    2014-11-14

    In this paper, we demonstrate compact and accessible squeezed-light magnetometry using four-wave mixing in a single hot rubidium vapor cell. The strong intrinsic coherence of the four-wave mixing process results in nonlinear magneto-optical rotation (NMOR) on each mode of a two-mode relative-intensity squeezed state. Finally, this framework enables 4.7 dB of quantum noise reduction while the opposing polarization rotation signals of the probe and conjugate fields add to increase the total signal to noise ratio.

  12. Symposium on New Materials for Nonlinear Optics

    NASA Astrophysics Data System (ADS)

    Marder, Seth R.

    1991-01-01

    The New Materials for Nonlinear Optics Symposium was held at the American Chemical Society National Meeting, in Boston on April 22 to 26, 1990. The meeting was a success. Throughout the week the average attendance was over 150 people/session. Several speakers had attendance over 300. The ACS organized a press conference about the meeting, held on Wednesday April 25, 1990 at 2 pm. At the time, the organizers devoted considerable time to educating the press about the importance of NLO research and the potential impact the NLO devices will have on the average person. The American Chemical Society is publishing an ACS Symposium Series monograph edited by the symposium organizers, to provide a permanent record of the proceeding of this meeting.

  13. Pulse Shepherding in Nonlinear Fiber Optics

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Bergman, L.

    1996-01-01

    In a wavelength division multiplexed fiber system, where pulses on different wavelength beams may co-propagate in a single mode fiber, the cross-phase-modulation (CPM) effects caused by the nonlinearity of the optical fiber are unavoidable. In other words, pulses on different wavelength beams can interact with and affect each other through the intensity dependence of the refractive index of the fiber. Although CPM will not cause energy to be exchanged among the beams, the pulse shapes and locations on these beams can be altered significantly. This phenomenon makes possible the manipulation and control of pulses co-propagating on different wavelength beams through the introduction of a shepherd pulse at a separate wavelength. How this can be accomplished is demonstrated in this paper.

  14. Development of organic nonlinear optical materials

    NASA Astrophysics Data System (ADS)

    Sounik, J.; Norwood, R.; McCulloch, I.; Song, K.; Demartino, R.

    1992-10-01

    The design of organic polymers as active mediums for nonlinear optics has attracted much attention because their nature of versatility in synthetic chemistry and in fabrication. A series of new side chain polymers were synthesized and characterized for the second and third order NLO applications. Linear copolymers containing maleic anhydride as an active functional group on the main chain were prepared in this work. The maleic anhydride group reacts, by ring opening esterification with an appropriate alcohol containing an NLO functionality. These copolymers were also found to be suitable for branching or crosslinking reactions with alpha, omega-diols. A series of substituted silicon and aluminum phthalocyanines has been synthesized to study their third order nonlinear responses. A nitro/amino substituted aluminum phthalocyanine has been made along with mixtures of benzo-substituted silicon phthalocyanines. A synthetic route has been investigated to directly give donor acceptor phthalocyanines. To increase mechanical property of phthalocyanine compounds, copolymers with MMA have been synthesized and characterized. All of the copolymers show excellent film forming characteristics.

  15. Absorbing Boundary Conditions For Optical Pulses In Dispersive, Nonlinear Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Kwak, Dochan (Technical Monitor)

    1995-01-01

    This paper will present results in computational nonlinear optics. An algorithm will be described that provides absorbing boundary conditions for optical pulses in dispersive, nonlinear materials. A new numerical absorber at the boundaries has been developed that is responsive to the spectral content of the pulse. Also, results will be shown of calculations of 2-D electromagnetic nonlinear waves computed by directly integrating in time the nonlinear vector Maxwell's equations. The results will include simulations of "light bullet" like pulses. Here diffraction and dispersion will be counteracted by nonlinear effects. Comparisons will be shown of calculations that use the standard boundary conditions and the new ones.

  16. Large nonlocal nonlinear optical response of castor oil

    NASA Astrophysics Data System (ADS)

    Souza, Rogério F.; Alencar, Márcio A. R. C.; Meneghetti, Mario R.; Hickmann, Jandir M.

    2009-09-01

    The nonlocal nonlinearity of castor oil was investigated using the Z-scan technique in the CW regime at 514 nm and in femtosecond regime at 810 nm. Large negative nonlinear refractive indexes of thermal origin, thermo-optical coefficients and degree of nonlocality were obtained for both laser excitation wavelengths. The results indicate that the electronic part of the nonlinear refractive index and nonlinear absorption were negligible. Our results suggest that castor oil is promising candidate as a nonlinear medium for several nonlocal optical applications, such as in spatial soliton propagation, as well as a dispersant agent in the measurement of absorptive properties of nanoparticles.

  17. Composite structures for the enhancement of nonlinear optical materials.

    PubMed

    Neeves, A E; Birnboim, M H

    1988-12-01

    Calculations of the nonlinear optical behavior are developed for model composites consisting of nanospheres with a metallic core and a nonlinear shell suspended in a nonlinear medium. The concept for the enhancement of optical phase conjugation from all these nonlinear regions is that the optical field can be concentrated both inside and in the neighborhood of the metallic core, aided by surface-mediated plasmon resonance. Calculations for gold cores and aluminum cores indicate that phase-conjugate reflectivity enhancements of 10(8) may be possible. PMID:19746133

  18. A Photonic Basis for Deriving Nonlinear Optical Response

    ERIC Educational Resources Information Center

    Andrews, David L.; Bradshaw, David S.

    2009-01-01

    Nonlinear optics is generally first presented as an extension of conventional optics. Typically the subject is introduced with reference to a classical oscillatory electric polarization, accommodating correction terms that become significant at high intensities. The material parameters that quantify the extent of the nonlinear response are cast as…

  19. Optical bistability in a nonlinear-shell-coated metallic nanoparticle

    PubMed Central

    Chen, Hongli; Zhang, Youming; Zhang, Baile; Gao, Lei

    2016-01-01

    We provide a self-consistent mean field approximation in the framework of Mie scattering theory to study the optical bistability of a metallic nanoparticle coated with a nonlinear shell. We demonstrate that the nanoparticle coated with a weakly nonlinear shell exhibits optical bistability in a broad range of incident optical intensity. This optical bistability critically relies on the geometry of the shell-coated nanoparticle, especially the fractional volume of the metallic core. The incident wavelength can also affect the optical bistability. Through an optimization-like process, we find a design with broader bistable region and lower threshold field by adjusting the size of the nonlinear shell, the fractional volume of the metallic core, and the incident wavelength. These results may find potential applications in optical bistable devices such as all-optical switches, optical transistors and optical memories. PMID:26907967

  20. Optical bistability in a nonlinear-shell-coated metallic nanoparticle

    NASA Astrophysics Data System (ADS)

    Chen, Hongli; Zhang, Youming; Zhang, Baile; Gao, Lei

    2016-02-01

    We provide a self-consistent mean field approximation in the framework of Mie scattering theory to study the optical bistability of a metallic nanoparticle coated with a nonlinear shell. We demonstrate that the nanoparticle coated with a weakly nonlinear shell exhibits optical bistability in a broad range of incident optical intensity. This optical bistability critically relies on the geometry of the shell-coated nanoparticle, especially the fractional volume of the metallic core. The incident wavelength can also affect the optical bistability. Through an optimization-like process, we find a design with broader bistable region and lower threshold field by adjusting the size of the nonlinear shell, the fractional volume of the metallic core, and the incident wavelength. These results may find potential applications in optical bistable devices such as all-optical switches, optical transistors and optical memories.

  1. Optical bistability in a nonlinear-shell-coated metallic nanoparticle.

    PubMed

    Chen, Hongli; Zhang, Youming; Zhang, Baile; Gao, Lei

    2016-01-01

    We provide a self-consistent mean field approximation in the framework of Mie scattering theory to study the optical bistability of a metallic nanoparticle coated with a nonlinear shell. We demonstrate that the nanoparticle coated with a weakly nonlinear shell exhibits optical bistability in a broad range of incident optical intensity. This optical bistability critically relies on the geometry of the shell-coated nanoparticle, especially the fractional volume of the metallic core. The incident wavelength can also affect the optical bistability. Through an optimization-like process, we find a design with broader bistable region and lower threshold field by adjusting the size of the nonlinear shell, the fractional volume of the metallic core, and the incident wavelength. These results may find potential applications in optical bistable devices such as all-optical switches, optical transistors and optical memories. PMID:26907967

  2. All-optical probing of the nonlinear acoustics of a crack.

    PubMed

    Mezil, Sylvain; Chigarev, Nikolay; Tournat, Vincent; Gusev, Vitalyi

    2011-09-01

    Experiments with an all-optical method for the study of the nonlinear acoustics of cracks in solids are reported. Nonlinear acoustic waves are initiated by the absorption of radiation from a pair of laser beams intensity modulated at two different frequencies. The detection of acoustic waves at mixed frequencies, absent in the frequency spectrum of the heating lasers, by optical interferometry or deflectometry provides unambiguous evidence of the elastic nonlinearity of the crack. The high contrast in crack imaging achieved by remote optical monitoring of the nonlinear acoustic processes is due to the strong dependence of the efficiency of optoacoustic conversion on the state of the crack. The highest acoustic nonlinearity is observed in the transitional state of the crack, which is intermediate between the open and the closed ones. PMID:21886240

  3. Revisiting interferences for measuring and optimizing optical nonlinearities

    NASA Astrophysics Data System (ADS)

    Billard, F.; Béjot, P.; Hertz, E.; Lavorel, B.; Faucher, O.

    2013-07-01

    A method based on optical interferences for measuring optical nonlinearities is presented. In a proof-of-principle experiment, the technique is applied to the experimental determination of the intensity dependence of the photoionization process. It is shown that it can also be used to control and optimize the nonlinear process itself at constant input energy. The presented strategy leads to enhancements that can reach several orders of magnitude for highly nonlinear processes.

  4. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  5. Nonlinear photoluminescence of fullerene-doped optical glasses

    SciTech Connect

    Zeng, Heping; Sun, Zhenrong; Segawa, Yusaburo; Lin, Fucheng; Mao, Sen; Xu, Zhizhan

    2001-06-01

    Strong broadband white photoluminescence was observed in fullerene-doped phosphate and fluorophosphate optical glasses irradiated by an ultraviolet laser. Microphotoluminescence measurements demonstrated the existence of microislands in those amorphous glasses, where fullerene dopants provided high photosensitivity and optical nonlinearity. Nonlinear photoluminescence was observed under ultralow continuous-wave laser excitations. The photoluminescence peak wavelengths were demonstrated to depend nonlinearly on the laser excitation power. {copyright} 2001 American Institute of Physics.

  6. Automated seeding-based nuclei segmentation in nonlinear optical microscopy.

    PubMed

    Medyukhina, Anna; Meyer, Tobias; Heuke, Sandro; Vogler, Nadine; Dietzek, Benjamin; Popp, Jürgen

    2013-10-01

    Nonlinear optical (NLO) microscopy based, e.g., on coherent anti-Stokes Raman scattering (CARS) or two-photon-excited fluorescence (TPEF) is a fast label-free imaging technique, with a great potential for biomedical applications. However, NLO microscopy as a diagnostic tool is still in its infancy; there is a lack of robust and durable nuclei segmentation methods capable of accurate image processing in cases of variable image contrast, nuclear density, and type of investigated tissue. Nonetheless, such algorithms specifically adapted to NLO microscopy present one prerequisite for the technology to be routinely used, e.g., in pathology or intraoperatively for surgical guidance. In this paper, we compare the applicability of different seeding and boundary detection methods to NLO microscopic images in order to develop an optimal seeding-based approach capable of accurate segmentation of both TPEF and CARS images. Among different methods, the Laplacian of Gaussian filter showed the best accuracy for the seeding of the image, while a modified seeded watershed segmentation was the most accurate in the task of boundary detection. The resulting combination of these methods followed by the verification of the detected nuclei performs high average sensitivity and specificity when applied to various types of NLO microscopy images. PMID:24085213

  7. Bond models in linear and nonlinear optics

    NASA Astrophysics Data System (ADS)

    Aspnes, D. E.

    2015-08-01

    Bond models, also known as polarizable-point or mechanical models, have a long history in optics, starting with the Clausius-Mossotti relation but more accurately originating with Ewald's largely forgotten work in 1912. These models describe macroscopic phenomena such as dielectric functions and nonlinear-optical (NLO) susceptibilities in terms of the physics that takes place in real space, in real time, on the atomic scale. Their strengths lie in the insights that they provide and the questions that they raise, aspects that are often obscured by quantum-mechanical treatments. Statics versions were used extensively in the late 1960's and early 1970's to correlate NLO susceptibilities among bulk materials. Interest in NLO applications revived with the 2002 work of Powell et al., who showed that a fully anisotropic version reduced by more than a factor of 2 the relatively large number of parameters necessary to describe secondharmonic- generation (SHG) data for Si(111)/SiO2 interfaces. Attention now is focused on the exact physical meaning of these parameters, and to the extent that they represent actual physical quantities.

  8. Nonlinear optical diagnostics of diesel spray. Final report, August 3, 1987--July 31, 1991

    SciTech Connect

    Chang, R.K.

    1991-09-01

    The mechanisms of fuel spray development within engines, particularly processes including atomization, vaporization, and mixing of the fuel and air, are critical in the design and optimization of diesel engines. During the four years of DOE support, significant progress has been made toward furthering the understanding of nonlinear optical effects in fuel sprays and single liquid droplets with radius (a) much larger than the laser wavelength ({lambda}{sub input}), i.e., droplets with with large size parameters x = 2{pi}a/{lambda}{sub input}. The authors have attempted to apply nonlinear optical spectroscopy to determine the chemical composition of the droplet, the droplet morphology (size, shape, and index of refraction), and the physical properties of the droplet (surface tension and bulk viscosity). This research can be divided into two parts: (1) understanding of nonlinear optical effects: and (2) application of nonlinear optical spectroscopy and imaging to fuel droplets and sprays.

  9. Extended arrays for nonlinear susceptibility magnitude imaging.

    PubMed

    Ficko, Bradley W; Giacometti, Paolo; Diamond, Solomon G

    2015-10-01

    This study implements nonlinear susceptibility magnitude imaging (SMI) with multifrequency intermodulation and phase encoding. An imaging grid was constructed of cylindrical wells of 3.5-mm diameter and 4.2-mm height on a hexagonal two-dimensional 61-voxel pattern with 5-mm spacing. Patterns of sample wells were filled with 40-μl volumes of Fe3O4 starch-coated magnetic nanoparticles (mNPs) with a hydrodynamic diameter of 100 nm and a concentration of 25 mg/ml. The imaging hardware was configured with three excitation coils and three detection coils in anticipation that a larger imaging system will have arrays of excitation and detection coils. Hexagonal and bar patterns of mNP were successfully imaged (R2>0.9) at several orientations. This SMI demonstration extends our prior work to feature a larger coil array, enlarged field-of-view, effective phase encoding scheme, reduced mNP sample size, and more complex imaging patterns to test the feasibility of extending the method beyond the pilot scale. The results presented in this study show that nonlinear SMI holds promise for further development into a practical imaging system for medical applications. PMID:26124044

  10. Multimodal nonlinear optical microscopy used to discriminate epithelial ovarian cancer

    NASA Astrophysics Data System (ADS)

    Adur, J.; Pelegati, V. B.; de Thomaz, A. A.; Almeida, D. B.; Bottcher-Luiz, F.; Andrade, L. A. L. A.; Cesar, C. L.

    2011-07-01

    We used human specimens of epithelial ovarian cancer (serous type) to test the feasibility of nonlinear imaging as complementary tools for ovarian cancer diagnosis. Classical hematoxylin-and-eosin stained sections were applied to combining two-photon excitation fluorescence (TPEF), second (SHG), and third (THG) harmonic microscopy within the same imaging platform. We show that strong TPEF + SHG + THG signals can be obtained in fixed samples stained with Hematoxylin & Eosin (H&E) stored for a very long time and that H&E staining enhanced the THG signal. We demonstrate using anisotropy and morphological measurements, that SHG and THG of stained optical sections allow reproducible identification of neoplastic features such as architectural alterations of collagen fibrils at different stages of the neoplastic transformation and cellular atypia. Taken together, these results suggest that, with our viable imaging system, we can qualitatively and quantitatively assess endogenous optical biomarkers of the ovarian tissue with SHG and THG microscopy. This imaging capability may prove to be highly valuable in aiding to determine structural changes at the cellular and tissue levels, which may contribute to the development of new diagnostic techniques.

  11. EDITORIAL: Nonlinear optical manipulation, patterning and control in nano- and micro-scale systems Nonlinear optical manipulation, patterning and control in nano- and micro-scale systems

    NASA Astrophysics Data System (ADS)

    Denz, Cornelia; Simoni, Francesco

    2009-03-01

    Nonlinearities are becoming more and more important for a variety of applications in nanosciences, bio-medical sciences, information processing and photonics. For applications at the crossings of these fields, especially microscopic and nanoscopic imaging and manipulation, nonlinearities play a key role. They may range from simple nonlinear parameter changes up to applications in manipulating, controlling and structuring material by light, or the manipulation of light by light itself. It is this area between basic nonlinear optics and photonic applications that includes `hot' topics such as ultra-resolution optical microscopy, micro- and nanomanipulation and -structuring, or nanophotonics. This special issue contains contributions in this field, many of them from the International Conference on Nonlinear Microscopy and Optical Control held in conjunction with a network meeting of the ESF COST action MP0604 `Optical Micromanipulation by Nonlinear Nanophotonics', 19-22 February 2008, Münster, Germany. Throughout this special issue, basic investigations of material structuring by nonlinear light--matter interaction, light-induced control of nanoparticles, and novel nonlinear material investigation techniques, are presented, covering the basic field of optical manipulation and control. These papers are followed by impressive developments of optical tweezers. Nowadays, optical phase contrast tweezers, twin and especially multiple beam traps, develop particle control in a new dimension: particles can be arranged, sorted and identified with high throughput. One of the most prominent forthcoming applications of optical tweezers is in the field of microfluidics. The action of light on fluids will open new horizons in microfluidic manipulation and control. The field of optical manipulation and control is a very broad field that has developed in an impressive way, in a short time, in Europe with the installation of the MP0604 network. Top researchers from 19 countries are

  12. Fiber-optic fluorescence imaging

    PubMed Central

    Flusberg, Benjamin A; Cocker, Eric D; Piyawattanametha, Wibool; Jung, Juergen C; Cheung, Eunice L M; Schnitzer, Mark J

    2010-01-01

    Optical fibers guide light between separate locations and enable new types of fluorescence imaging. Fiber-optic fluorescence imaging systems include portable handheld microscopes, flexible endoscopes well suited for imaging within hollow tissue cavities and microendoscopes that allow minimally invasive high-resolution imaging deep within tissue. A challenge in the creation of such devices is the design and integration of miniaturized optical and mechanical components. Until recently, fiber-based fluorescence imaging was mainly limited to epifluorescence and scanning confocal modalities. Two new classes of photonic crystal fiber facilitate ultrashort pulse delivery for fiber-optic two-photon fluorescence imaging. An upcoming generation of fluorescence imaging devices will be based on microfabricated device components. PMID:16299479

  13. Optical and Nonlinear Optical Response of Light Sensor Thin Films

    PubMed Central

    Liu, Huimin; Rua, Armando; Vasquez, Omar; Vikhnin, Valentin S.; Fernandez, Felix E.; Fonseca, Luis F.; Resto, Oscar; Weisz, Svi Z.

    2005-01-01

    For potential ultrafast optical sensor application, both VO2 thin films and nanocomposite crystal-Si enriched SiO2 thin films grown on fused quartz substrates were successfully prepared using pulsed laser deposition (PLD) and RF co-sputtering techniques. In photoluminescence (PL) measurement c-Si/SiO2 film contains nanoparticles of crystal Si exhibits strong red emission with the band maximum ranging from 580 to 750 nm. With ultrashort pulsed laser excitation all films show extremely intense and ultrafast nonlinear optical (NLO) response. The recorded holography from all these thin films in a degenerate-four-wave-mixing configuration shows extremely large third-order response. For VO2 thin films, an optically induced semiconductor-to-metal phase transition (PT) immediately occurred upon laser excitation. it accompanied. It turns out that the fast excited state dynamics was responsible to the induced PT. For c-Si/SiO2 film, its NLO response comes from the contribution of charge carriers created by laser excitation in conduction band of the c-Si nanoparticles. It was verified by introducing Eu3+ which is often used as a probe sensing the environment variations. It turns out that the entire excited state dynamical process associated with the creation, movement and trapping of the charge carriers has a characteristic 500 ps duration.

  14. Nonlinear optical processes in liquid crystals and applications in optical switching

    NASA Astrophysics Data System (ADS)

    Zhao, Shuo

    This dissertation research completes the exploration and development of the theoretical framework for collective liquid crystalline optical nonlinearities capable of response speeds in the microseconds---nanoseconds scale, which is more than 1000 times faster than the conventional liquid crystal (LC) response speed. Also explored in this dissertation are utilizations of these new discoveries to achieve all-optical switching. This work demonstrates all-optical switching using nonlinear orientational and thermal effects, respectively, in pure and dye-doped twisted nematic liquid crystal (TNLC) cells set between crossed polarizers. In the former case, the flow of liquid crystal molecules is generated by Maxwell stress and thereby exerts a torque on the liquid crystal. The resulting reorientation changes the effective birefringence of the liquid crystal, affecting the overall transmission. In dye-doped twisted nematics, the absorption of dye enhances laser heating in the liquid crystal, which leads to reduction of the order parameter and the corresponding macroscopic birefringence, finally making the transmission drop to zero. Following the sequences of these processes, detailed modeling for collective responses of liquid crystal and the time evolution of transmissions under short laser pulses are presented. Besides theoretical description and modeling, we demonstrate the nonlinear optical switching experimentally. The switching threshold and time are consistent with the simulation results. While dye-doped liquid crystals have a low threshold for nonlinear switching, pure twisted nematics possess high transparency in the entire visible and nearinfrared spectrum. These findings are believed to advance the current arsenal of highperformance materials for integration/use in advanced optical systems designed for sensor protection; laser hardening; and other beam/image switching, sensing, and processing operations.

  15. Broad Bandwidth Laser and Nonlinear Optical Sources for OCT

    NASA Astrophysics Data System (ADS)

    Unterhuber, Angelika; Považay, Boris; Aguirre, Aaron D.; Chen, Yu; Kärtner, Franz X.; Fujimoto, James G.; Drexler, Wolfgang

    OCT achieves very high axial image resolutions independent of focusing conditions because the axial and transverse resolutions are determined independently by different physical mechanisms. This implies that axial OCT resolution can be enhanced using broad bandwidth, low coherence length light sources. The light source not only determines axial OCT resolution via its bandwidth and central emission wavelength but also determines the penetration in the sample (biological tissue), the contrast of the tomogram, and the OCT transverse resolution. A minimum output power with low amplitude noise is also necessary to enable high sensitivity and high-speed - real time - OCT imaging. Hence, it is obvious that the light source is the key technological parameter for an OCT system, and proper choice is imperative. Ultrabroad bandwidth light source technology enables ultrahigh-resolution OCT in the visible and near-infrared wavelength region. Kerr-lens mode-locked solid-state lasers can generate broad bandwidth spectra spanning up to one optical octave. Nonetheless they are restricted to the fluorescence bands of the laser crystal and have a complex architecture making them expensive and preventing widespread industrial use. Spectra far broader than one optical octave can be produced via nonlinear propagation of laser pulses having only moderate energies of a few nJ in microstructured fibers. Complex fibers with one, two, or even no zero-dispersion wavelength can be designed and fabricated to fulfill special requirements as large optical bandwidth and low noise.

  16. Linear and nonlinear optical properties of chalcogenide microstructured optical fibers

    NASA Astrophysics Data System (ADS)

    Trolès, Johann; Brilland, Laurent; Caillaud, Celine; Renversez, Gilles; Mechin, David; Adam, Jean-Luc

    2015-03-01

    Chalcogenide glasses are known for their large transparency in the mid-infrared and their high linear refractive index (>2). They present also a high non-linear coefficient (n2), 100 to 1000 times larger than for silica, depending on the composition. we have developed a casting method to prepare the microstructured chalcogenide preform. This method allows optical losses as low as 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various chalcogenide MOFs operating in the IR range has been fabricated in order to associate the high non-linear properties of these glasses and the original MOF properties. For example, small core fibers have been drawn to enhance the non linearities for telecom applications such as signal regeneration and generation of supercontinuum sources. On another hand, in the 3-12 µm window, single mode fibers and exposed core fibers have been realized for Gaussian beams propagation and sensors applications respectively.

  17. Hepatic lesions segmentation in ultrasound nonlinear imaging

    NASA Astrophysics Data System (ADS)

    Kissi, Adelaide A.; Cormier, Stephane; Pourcelot, Leandre; Tranquart, Francois

    2005-04-01

    Doppler has been used for many years for cardiovascular exploration in order to visualize the vessels walls and anatomical or functional diseases. The use of ultrasound contrast agents makes it possible to improve ultrasonic information. Nonlinear ultrasound imaging highlights the detection of these agents within an organ and hence is a powerful technique to image perfusion of an organ in real-time. The visualization of flow and perfusion provides important information for the diagnosis of various diseases as well as for the detection of tumors. However, the images are buried in noise, the speckle, inherent in the image formation. Furthermore at portal phase, there is often an absence of clear contrast between lesions and surrounding tissues because the organ is filled with agents. In this context, we propose a new method of automatic liver lesions segmentation in nonlinear imaging sequences for the quantification of perfusion. Our method of segmentation is divided into two stages. Initially, we developed an anisotropic diffusion step which raised the structural characteristics to eliminate the speckle. Then, a fuzzy competitive clustering process allowed us to delineate liver lesions. This method has been used to detect focal hepatic lesions (metastasis, nodular hyperplasia, adenoma). Compared to medical expert"s report obtained on 15 varied lesions, the automatic segmentation allows us to identify and delineate focal liver lesions during the portal phase which high accuracy. Our results show that this method improves markedly the recognition of focal hepatic lesions and opens the way for future precise quantification of contrast enhancement.

  18. Nonlinear fiber applications for ultrafast all-optical signal processing

    NASA Astrophysics Data System (ADS)

    Kravtsov, Konstantin

    In the present dissertation different aspects of all-optical signal processing, enabled by the use of nonlinear fibers, are studied. In particular, we focus on applications of a novel heavily GeO2-doped (HD) nonlinear fiber, that appears to be superior to many other types of nonlinear fibers because of its high nonlinearity and suitability for the use in nonlinear optical loop mirrors (NOLMs). Different functions, such as all-optical switching, thresholding, and wavelength conversion, are demonstrated with the HD fibers in the NOLM configuration. These basic functions are later used for realization of ultrafast time-domain demultiplexers, clock recovery, detectors of short pulses in stealth communications, and primitive elements for analog computations. Another important technology that benefits from the use of nonlinear fiber-based signal processing is optical code-division multiple access (CDMA). It is shown in both theory and experiment that all-optical thresholding is a unique way of improving existing detection methods for optical CDMA. Also, it is the way of implementation of true asynchronous optical spread-spectrum networks, which allows full realization of optical CDMA potential. Some aspects of quantum signal processing and manipulation of quantum states are also studied in this work. It is shown that propagation and collisions of Thirring solitons lead to a substantial squeezing of quantum states, which may find applications for generation of squeezed light.

  19. Nonlinear optical studies of curcumin metal derivatives with cw laser

    NASA Astrophysics Data System (ADS)

    Henari, F. Z.; Cassidy, S.

    2015-03-01

    We report on measurements of the nonlinear refractive index and nonlinear absorption coefficients for curcumin and curcumin metal complexes of boron, copper, and iron at different wavelengths using the Z-scan technique. These materials are found to be novel nonlinear media. It was found that the addition of metals slightly influences its nonlinearity. These materials show a large negative nonlinear refractive index of the order of 10-7 cm2/W and negative nonlinear absorption of the order of 10-6 cm/W. The origin of the nonlinearity was investigated by comparison of the formalism that is known as the Gaussian decomposition model with the thermal lens model. The optical limiting behavior based on the nonlinear refractive index was also investigated.

  20. Nonlinear optical studies of curcumin metal derivatives with cw laser

    SciTech Connect

    Henari, F. Z. Cassidy, S.

    2015-03-30

    We report on measurements of the nonlinear refractive index and nonlinear absorption coefficients for curcumin and curcumin metal complexes of boron, copper, and iron at different wavelengths using the Z-scan technique. These materials are found to be novel nonlinear media. It was found that the addition of metals slightly influences its nonlinearity. These materials show a large negative nonlinear refractive index of the order of 10{sup −7} cm{sup 2}/W and negative nonlinear absorption of the order of 10{sup −6} cm/W. The origin of the nonlinearity was investigated by comparison of the formalism that is known as the Gaussian decomposition model with the thermal lens model. The optical limiting behavior based on the nonlinear refractive index was also investigated.

  1. Advances in nonlinear optical materials and devices

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1991-01-01

    The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

  2. Giant Nonlinearity of an Optically Reconfigurable Plasmonic Metamaterial.

    PubMed

    Ou, Jun-Yu; Plum, Eric; Zhang, Jianfa; Zheludev, Nikolay I

    2016-01-27

    Metamaterial nanostructures actuated by light give rise to a large optical nonlinearity. Plasmonic metamolecules on a flexible support structure cut from a dielectric membrane of nanoscale thickness are rearranged by optical illumination. This changes the optical properties of the strongly coupled plasmonic structure and therefore results in modulation of light with light. PMID:26619205

  3. Modeling and compensation of transmitter nonlinearity in coherent optical OFDM.

    PubMed

    Amiralizadeh, Siamak; Nguyen, An T; Rusch, Leslie A

    2015-10-01

    We present a comprehensive study of nonlinear distortions from an optical OFDM transmitter. Nonlinearities are introduced by the combination of effects from the digital-to-analog converter (DAC), electrical power amplifier (PA) and optical modulator in the presence of high peak-to-average power ratio (PAPR). We introduce parameters to quantify the transmitter nonlinearity. High input backoff avoids OFDM signal compression from the PA, but incurs high penalties in power efficiency. At low input backoff, common PAPR reduction techniques are not effective in suppressing the PA nonlinear distortion. A bit error distribution investigation shows a technique combining nonlinear predistortion with PAPR mitigation could achieve good power efficiency by allowing low input backoff. We use training symbols to extract the transmitter nonlinear function. We show that piecewise linear interpolation (PLI) leads to an accurate transmitter nonlinearity characterization. We derive a semi-analytical solution for bit error rate (BER) that validates the PLI approximation accurately captures transmitter nonlinearity. The inverse of the PLI estimate of the nonlinear function is used as a predistorter to suppress transmitter nonlinearity. We investigate performance of the proposed scheme by Monte Carlo simulations. Our simulations show that when DAC resolution is more than 4 bits, BER below forward error correction limit of 3.8 × 10(-3) can be achieved by using predistortion with very low input power backoff for electrical PA and optical modulator. PMID:26480133

  4. Brain plasticity and functionality explored by nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; Allegra, L.; Buffelli, M.; Cesare, P.; D'Angelo, E.; Gandolfi, D.; Grasselli, G.; Lotti, J.; Mapelli, J.; Strata, P.; Pavone, F. S.

    2010-02-01

    In combination with fluorescent protein (XFP) expression techniques, two-photon microscopy has become an indispensable tool to image cortical plasticity in living mice. In parallel to its application in imaging, multi-photon absorption has also been used as a tool for the dissection of single neurites with submicrometric precision without causing any visible collateral damage to the surrounding neuronal structures. In this work, multi-photon nanosurgery is applied to dissect single climbing fibers expressing GFP in the cerebellar cortex. The morphological consequences are then characterized with time lapse 3-dimensional two-photon imaging over a period of minutes to days after the procedure. Preliminary investigations show that the laser induced fiber dissection recalls a regenerative process in the fiber itself over a period of days. These results show the possibility of this innovative technique to investigate regenerative processes in adult brain. In parallel with imaging and manipulation technique, non-linear microscopy offers the opportunity to optically record electrical activity in intact neuronal networks. In this work, we combined the advantages of second-harmonic generation (SHG) with a random access (RA) excitation scheme to realize a new microscope (RASH) capable of optically recording fast membrane potential events occurring in a wide-field of view. The RASH microscope, in combination with bulk loading of tissue with FM4-64 dye, was used to simultaneously record electrical activity from clusters of Purkinje cells in acute cerebellar slices. Complex spikes, both synchronous and asynchronous, were optically recorded simultaneously across a given population of neurons. Spontaneous electrical activity was also monitored simultaneously in pairs of neurons, where action potentials were recorded without averaging across trials. These results show the strength of this technique in describing the temporal dynamics of neuronal assemblies, opening promising

  5. Blue-phase liquid crystal cored optical fiber array with photonic bandgaps and nonlinear transmission properties.

    PubMed

    Khoo, Iam Choon; Hong, Kuan Lung; Zhao, Shuo; Ma, Ding; Lin, Tsung-Hsien

    2013-02-25

    Blue-phase liquid crystal (BPLC) is introduced into the pores of capillary arrays to fabricate fiber arrays. Owing to the photonic-crystals like properties of BPLC, these fiber arrays exhibit temperature dependent photonic bandgaps in the visible spectrum. With the cores maintained in isotropic as well as the Blue phases, the fiber arrays allow high quality image transmission when inserted in the focal plane of a 1x telescope. Nonlinear transmission and optical limiting action on a cw white-light continuum laser is also observed and is attributed to laser induced self-defocusing and propagation modes changing effects caused by some finite absorption of the broadband laser at the short wavelength regime. These nonlinear and other known electro-optical properties of BPLC, in conjunction with their fabrication ease make these fiber arrays highly promising for imaging, electro-optical or all-optical modulation, switching and passive optical limiting applications. PMID:23481965

  6. Nanodispersion, nonlinear image filtering, and materials classification

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.; Lee, Jun S.

    2011-06-01

    Polyethylene terephthalate-alumina nano-composites from two production processes gave rise to materials H and T, further divided into four and, respectively, three classes of belonging. Electron microscope images of the materials had been visually scored by an expert in terms of an index, β, aimed at assessing filler dispersion and distribution. These properties characterize the nano-composite. Herewith a classification algorithm which includes image spatial differentiation and non-linear filtering interlaced with multivariate statistics is applied to the same images of materials Hand T. The classification algorithm depends on a few parameters, which are automatically determined by maximizing a figure of merit in the supervised training stage. The classifier output is a display on the plane of the first two principal components. By regressing the 1st principal component affinely against β a remarkable agreement is found between automated classification and visual scoring of material H. The regression result for materialT is not significant, because the assigned classes reduce from 3 to 2, both by visual and automated scoring. The output from the non-linear image filter can be related to filler dispersion and distribution.

  7. Focused optical and acoustic beams in media with nonlinear absorption

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.; Sukhorukov, A. A.

    1996-11-01

    Optical and acoustic beams are known to be useful for medical and biological applications, such as diagnostics, surgery, etc. At high intensities both nonlinear lens effects and nonlinear absorption can be significant for the beams. The nonlinear absorption arises due to two-photon optical processes or acoustic shock wave formation. The present work is devoted to the theoretical description of nonlinear beam propagation and focal spot formation taking into account the competition between focusing, diffraction and absorption. We derived a new nonlinear integro- differential equation describing the spatial evolution of the beam width. The general analytical solution of this equation is obtained for arbitrary boundary conditions. The simple formulas are derived for the angle divergence in the far field, as well as for beam width at nonlinear waist. The results of the analysis of these key parameters in different situations are presented.

  8. Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging.

    PubMed

    Kumar, Sunil; Kamali, Tschackad; Levitte, Jonathan M; Katz, Ori; Hermann, Boris; Werkmeister, Rene; Považay, Boris; Drexler, Wolfgang; Unterhuber, Angelika; Silberberg, Yaron

    2015-05-18

    Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly alignment-free multimodal nonlinear optical microscope that is based on a single wide-band Ti:Sapphire femtosecond pulse laser source. Successful imaging tests have been realized on two exemplary biological samples, a canine femur bone and collagen fibrils harvested from a rat tail. Since the ultra-broad band-width femtosecond laser is a suitable source for performing high-resolution optical coherence tomography, a wide-field optical coherence tomography arm can be easily incorporated into the presented multimodal microscope making it a versatile optical imaging tool for noninvasive label-free bioimaging. PMID:26074561

  9. Fiber-optic nonlinear endomicroscopy with focus scanning by using shape memory alloy actuation

    NASA Astrophysics Data System (ADS)

    Wu, Yicong; Zhang, Yuying; Xi, Jiefeng; Li, Ming-Jun; Li, Xingde

    2010-11-01

    A miniature fiber optic endomicroscope with built-in dynamic focus scanning capability is developed for the first time for 3-D two-photon fluorescence (TPF) imaging of biological samples. Fast 2-D lateral beam scanning is realized by resonantly vibrating a double-clad fiber cantilever with a tubular piezoactuator. Slow axial scanning is achieved by moving the distal end of the imaging probe with an extremely compact electrically driven shape memory alloy (SMA). The 10-mm-long SMA allows 150-μm contractions with a driving voltage varying only from 50 to 100 mV. The response of the SMA contraction with the applied voltage is nonlinear, but repeatable and can be accurately calibrated. Depth-resolved imaging of acriflavine-stained biological tissues and unstained white paper with the endomicroscope is performed, and the results demonstrate the feasibility of 3-D nonlinear optical imaging with the SMA-based scanning fiber-optic endomicroscope.

  10. Third order nonlinear optical property of Bi₂Se₃.

    PubMed

    Lu, Shunbin; Zhao, Chujun; Zou, Yanhong; Chen, Shuqing; Chen, Yu; Li, Ying; Zhang, Han; Wen, Shuangchun; Tang, Dingyuan

    2013-01-28

    The third order nonlinear optical property of Bi₂Se₃, a kind of topological insulator (TI), has been investigated under femto-second laser excitation. The open and closed aperture Z-scan measurements were used to unambiguously distinguish the real and imaginary part of the third order optical nonlinearity of the TI. When excited at 800 nm, the TI exhibits saturable absorption with a saturation intensity of 10.12 GW/cm² and a modulation depth of 61.2%, and a giant nonlinear refractive index of 10⁻¹⁴ m²/W, almost six orders of magnitude larger than that of bulk dielectrics. This finding suggests that the TI:Bi₂Se₃ is indeed a promising nonlinear optical material and thus can find potential applications from passive laser mode locker to optical Kerr effect based photonic devices. PMID:23389188

  11. Nonlinear optics and crystalline whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode crystalline resonaors, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics.

  12. Subpicosecond optical pulse compression via an integrated nonlinear chirper.

    PubMed

    Peccianti, Marco; Ferrera, Marcello; Razzari, Luca; Morandotti, Roberto; Little, Brent E; Chu, Sai T; Moss, David J

    2010-04-12

    Photonic integrated circuits (PICs) capable of ultra-fast, signal processing are recognized as being fundamental for future applications involving ultra-short optical pulse propagation, including the ability to meet the exponentially growing global fiber-optic telecommunications bandwidth demand. Integrated all-optical signal processors would carry substantial benefits in terms of performance, cost, footprint, and energy efficiency. Here, we demonstrate an optical pulse compressor based on an integrated nonlinear chirper, capable of operating on a sub-picosecond (> 1Tb/s) time scale. It is CMOS compatible and based on a 45cm long, high index doped silica glass waveguide we achieve pulse compression at relatively low input peak powers, due to the high nonlinearity and low linear and nonlinear losses of the device. The flexibility of this platform in terms of nonlinearity and dispersion allows the implementation of several compression schemes. PMID:20588602

  13. Highly nonlocal optical nonlinearities in atoms trapped near a waveguide

    NASA Astrophysics Data System (ADS)

    Shahmoon, Ephraim; Grisins, Pjotrs; Stimming, Hans Peter; Mazets, Igor; Kurizki, Gershon

    2016-05-01

    Nonlinear optical phenomena are typically local. Here we predict the possibility of highly nonlocal optical nonlinearities for light propagating in atomic media trapped near a nano-waveguide, where long-range interactions between the atoms can be tailored. When the atoms are in an electromagnetically-induced transparency configuration, the atomic interactions are translated to long-range interactions between photons and thus to highly nonlocal optical nonlinearities. We derive and analyze the governing nonlinear propagation equation, finding a roton-like excitation spectrum for light and the emergence of long-range order in its output intensity. These predictions open the door to studies of unexplored wave dynamics and many-body physics with highly-nonlocal interactions of optical fields in one dimension.

  14. Topological nature of nonlinear optical effects in solids

    PubMed Central

    Morimoto, Takahiro; Nagaosa, Naoto

    2016-01-01

    There are a variety of nonlinear optical effects including higher harmonic generations, photovoltaic effects, and nonlinear Kerr rotations. They are realized by strong light irradiation to materials that results in nonlinear polarizations in the electric field. These are of great importance in studying the physics of excited states of the system as well as for applications to optical devices and solar cells. Nonlinear properties of materials are usually described by nonlinear susceptibilities, which have complex expressions including many matrix elements and energy denominators. On the other hand, a nonequilibrium steady state under an electric field periodic in time has a concise description in terms of the Floquet bands of electrons dressed by photons. We show theoretically, using the Floquet formalism, that various nonlinear optical effects, such as the shift current in noncentrosymmetric materials, photovoltaic Hall response, and photo-induced change of order parameters under the continuous irradiation of monochromatic light, can be described in a unified fashion by topological quantities involving the Berry connection and Berry curvature. We found that vector fields defined with the Berry connections in the space of momentum and/or parameters govern the nonlinear responses. This topological view offers a route to designing nonlinear optical materials. PMID:27386523

  15. Topological nature of nonlinear optical effects in solids.

    PubMed

    Morimoto, Takahiro; Nagaosa, Naoto

    2016-05-01

    There are a variety of nonlinear optical effects including higher harmonic generations, photovoltaic effects, and nonlinear Kerr rotations. They are realized by strong light irradiation to materials that results in nonlinear polarizations in the electric field. These are of great importance in studying the physics of excited states of the system as well as for applications to optical devices and solar cells. Nonlinear properties of materials are usually described by nonlinear susceptibilities, which have complex expressions including many matrix elements and energy denominators. On the other hand, a nonequilibrium steady state under an electric field periodic in time has a concise description in terms of the Floquet bands of electrons dressed by photons. We show theoretically, using the Floquet formalism, that various nonlinear optical effects, such as the shift current in noncentrosymmetric materials, photovoltaic Hall response, and photo-induced change of order parameters under the continuous irradiation of monochromatic light, can be described in a unified fashion by topological quantities involving the Berry connection and Berry curvature. We found that vector fields defined with the Berry connections in the space of momentum and/or parameters govern the nonlinear responses. This topological view offers a route to designing nonlinear optical materials. PMID:27386523

  16. Non-linear optics of ultrastrongly coupled cavity polaritons

    NASA Astrophysics Data System (ADS)

    Crescimanno, Michael; Liu, Bin; McMaster, Michael; Singer, Kenneth

    2016-05-01

    Experiments at CWRU have developed organic cavity polaritons that display world-record vacuum Rabi splittings of more than an eV. This ultrastrongly coupled polaritonic matter is a new regime for exploring non-linear optical effects. We apply quantum optics theory to quantitatively determine various non-linear optical effects including types of low harmonic generation (SHG and THG) in single and double cavity polariton systems. Ultrastrongly coupled photon-matter systems such as these may be the foundation for technologies including low-power optical switching and computing.

  17. Background estimation in nonlinear image restoration.

    PubMed

    van Kempen, G M; van Vliet, L J

    2000-03-01

    One of the essential ways in which nonlinear image restoration algorithms differ from linear, convolution-type image restoration filters is their capability to restrict the restoration result to nonnegative intensities. The iterative constrained Tikhonov-Miller (ICTM) algorithm, for example, incorporates the nonnegativity constraint by clipping all negative values to zero after each iteration. This constraint will be effective only when the restored intensities have near-zero values. Therefore the background estimation will have an influence on the effectiveness of the nonnegativity constraint of these algorithms. We investigated quantitatively the dependency of the performance of the ICTM, Carrington, and Richardson-Lucy algorithms on the estimation of the background and compared it with the performance of the linear Tikhonov-Miller restoration filter. We found that the performance depends critically on the background estimation: An underestimation of the background will make the nonnegativity constraint ineffective, which results in a performance that does not differ much from the Tikhonov-Miller filter performance. A (small) overestimation, however, degrades the performance dramatically, since it results in a clipping of object intensities. We propose a novel general method to estimate the background based on the dependency of nonlinear restoration algorithms on the background, and we demonstrate its applicability on real confocal images. PMID:10708022

  18. Exploring lipids with nonlinear optical microscopy in multiple biological systems

    NASA Astrophysics Data System (ADS)

    Alfonso-Garcia, Alba

    Lipids are crucial biomolecules for the well being of humans. Altered lipid metabolism may give rise to a variety of diseases that affect organs from the cardiovascular to the central nervous system. A deeper understanding of lipid metabolic processes would spur medical research towards developing precise diagnostic tools, treatment methods, and preventive strategies for reducing the impact of lipid diseases. Lipid visualization remains a complex task because of the perturbative effect exerted by traditional biochemical assays and most fluorescence markers. Coherent Raman scattering (CRS) microscopy enables interrogation of biological samples with minimum disturbance, and is particularly well suited for label-free visualization of lipids, providing chemical specificity without compromising on spatial resolution. Hyperspectral imaging yields large datasets that benefit from tailored multivariate analysis. In this thesis, CRS microscopy was combined with Raman spectroscopy and other label-free nonlinear optical techniques to analyze lipid metabolism in multiple biological systems. We used nonlinear Raman techniques to characterize Meibum secretions in the progression of dry eye disease, where the lipid and protein contributions change in ratio and phase segregation. We employed similar tools to examine lipid droplets in mice livers aboard a spaceflight mission, which lose their retinol content contributing to the onset of nonalcoholic fatty-liver disease. We also focused on atherosclerosis, a disease that revolves around lipid-rich plaques in arterial walls. We examined the lipid content of macrophages, whose variable phenotype gives rise to contrasting healing and inflammatory activities. We also proposed new label-free markers, based on lifetime imaging, for macrophage phenotype, and to detect products of lipid oxidation. Cholesterol was also detected in hepatitis C virus infected cells, and in specific strains of age-related macular degeneration diseased cells by

  19. Linear and nonlinear optical, mechanical, electrical and surface studies of a novel nonlinear optical crystal - Manganese mercury thiocyanate (MMTC)

    NASA Astrophysics Data System (ADS)

    Josephine Usha, R.; Sagayaraj, P.; Joseph, V.

    2014-12-01

    The highly efficient nonlinear optical single crystal of manganese mercury thiocyanate has been grown from slow evaporation solvent technique. The second harmonic generation and optical transmittance of the grown crystal are studied by Kurtz and Perry powder technique and spectroscopic absorbance spectrum. Mechanical behaviour is analyzed using Vickers microhardness test. The dielectric response of the grown crystal is studied as a function of the temperature and the results are discussed. Further, electronic properties such as plasma energy, Penngap, Fermi energy and electronic polarizability are evaluated. Third order nonlinear optical studies are performed using by single beam Z-scan technique using Nd:YAG laser and parameters such as nonlinear refractive index n2, absorption co-efficient β and nonlinear optical susceptibility χ(3) are evaluated for the grown crystal. The surface of the grown crystal is analyzed with field emission scanning electron microscope and atomic force microscope analyses.

  20. Linear and nonlinear optical, mechanical, electrical and surface studies of a novel nonlinear optical crystal - manganese mercury thiocyanate (MMTC).

    PubMed

    Josephine Usha, R; Sagayaraj, P; Joseph, V

    2014-12-10

    The highly efficient nonlinear optical single crystal of manganese mercury thiocyanate has been grown from slow evaporation solvent technique. The second harmonic generation and optical transmittance of the grown crystal are studied by Kurtz and Perry powder technique and spectroscopic absorbance spectrum. Mechanical behaviour is analyzed using Vickers microhardness test. The dielectric response of the grown crystal is studied as a function of the temperature and the results are discussed. Further, electronic properties such as plasma energy, Penngap, Fermi energy and electronic polarizability are evaluated. Third order nonlinear optical studies are performed using by single beam Z-scan technique using Nd:YAG laser and parameters such as nonlinear refractive index n2, absorption co-efficient β and nonlinear optical susceptibility χ((3)) are evaluated for the grown crystal. The surface of the grown crystal is analyzed with field emission scanning electron microscope and atomic force microscope analyses. PMID:24945865

  1. Nonlinear dynamics of quantum cascade lasers with optical feedback

    NASA Astrophysics Data System (ADS)

    Jumpertz, L.; Ferré, S.; Schires, K.; Carras, M.; Grillot, F.

    2015-01-01

    Quantum Cascade (QC) lasers are widely used in optical communications, high-resolution spectroscopy, imaging, and remote sensing due to their wide spectral range, going from mid-infrared to the terahertz regime. The dynamics of QClasers are dominated by their ultrafast carrier lifetime, typically of the order of a few picoseconds. The combination of optical nonlinearities and ultrafast dynamics is an interesting feature of QC-lasers, and investigating the dynamical properties of such lasers gives unprecedented insights into the underlying physics of the components, which is of interest for the next generation of QC devices. A particular feature of QC-lasers is the absence of relaxation oscillations, which is the consequence of the relatively short carrier lifetime compared to photon lifetime. Optical feedback (i.e. self-injection) is known to be a robust technique for stabilizing or synchronizing a free-running laser, however its effect on QC-lasers remains mostly unexplored. This work aims at discussing the dynamical properties of QC-lasers operating under optical feedback by employing a novel set of rate equations taking into account the upper and lower lasing levels, the bottom state as well as the gain stage's cascading. This work analyzes the static laser properties subject to optical feedback and provides a comparison with experiments. Spectral analysis reveals that QC-lasers undergo distinct feedback regimes depending on the phase and amplitude of the reinjected field, and that the coherence-collapse regime only appears in a very narrow range of operation, making such lasers much more stable than their interband counterparts.

  2. Dual-polarization plasmonic metasurface for nonlinear optics.

    PubMed

    Cala' Lesina, Antonino; Ramunno, Lora; Berini, Pierre

    2015-06-15

    A plasmonic metasurface for the enhancement of nonlinear optical effects is proposed. The metasurface can simultaneously enhance perpendicularly polarized electric fields in the same volume. We illustrate application of the metasurface to the production of Terahertz radiation via the parametric process of difference frequency generation in 4¯3m non-centro symmetric materials, e.g., GaAs, which has a large second-order nonlinear susceptibility. An enhancement over bulk of almost two orders of magnitude near the surface supports the use of the proposed structure for thin-film, surface-based, or chip-based nonlinear optical applications for several crystal classes. PMID:26076284

  3. Prediction of nonlinear optical properties of large organic molecules

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.

    1992-01-01

    The preparation of materials with large nonlinear responses usually requires involved synthetic processes. Thus, it is very advantageous for materials scientists to have a means of predicting nonlinear optical properties. The prediction of nonlinear optical properties has to be addressed first at the molecular level and then as bulk material. For relatively large molecules, two types of calculations may be used, which are the sum-over-states and the finite-field approach. The finite-field method was selected for this research, because this approach is better suited for larger molecules.

  4. Third-Order Nonlinear Optical Properties and Optical Switching of Palladium (I) Complex

    NASA Astrophysics Data System (ADS)

    Manjunatha, K. B.; Dileep, R.; Vikas, M. Shelar; Umesh, G.; Satyanarayan, M. N.; Bhat, B. Ramachandra

    2011-10-01

    We report the third-order nonlinear optical, optical power limiting and optical switching study of palladium-N-(2-pyridyl)-N'- (5-amino salicylidene) hydrazine triphenylphosphine, using Z-scan technique and pump-probe technique. The measured nonlinear refractive index is n2 = -6.022×10-9 esu. The complex exhibits the reverse saturable absorption (RSA), the nonlinear absorption coefficient of β = 10.748×10-9 m/W. The good optical power limiting and optical switching behavior were observed in this complex. These suggest that this complex is a potential molecule for photonic applications.

  5. Retinal Imaging: Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Goncharov, A. S.; Iroshnikov, N. G.; Larichev, Andrey V.

    This chapter describes several factors influencing the performance of ophthalmic diagnostic systems with adaptive optics compensation of human eye aberration. Particular attention is paid to speckle modulation, temporal behavior of aberrations, and anisoplanatic effects. The implementation of a fundus camera with adaptive optics is considered.

  6. 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.

  7. 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.

  8. Nonlinear optical effects in colloidal carbon nanohorns—a new optical limiting material

    NASA Astrophysics Data System (ADS)

    Dengler, Stefanie; Muller, Olivier; Hege, Cordula; Eberle, Bernd

    2016-09-01

    Many carbon based nanomaterials exhibit nonlinear optical response over a large wavelength range when irradiated with intense laser light what makes them promising candidates for optical limiting purposes. Besides nonlinear absorption some of these well studied nanostructures like carbon nanotubes or carbon black owe their prominent limiting efficiency particularly to induced nonlinear scattering. In this paper, our investigations on carbon nanohorns are presented—a new and very promising nonlinear optical material. It offers excellent properties like a low optical limiting threshold and a high nonlinear attenuation when tested with nanosecond laser pulses at wavelengths of 532 nm or 1064 nm. At moderate irradiation levels near the nonlinear threshold our measurements performed on colloidal carbon nanohorns reveal broadband nonlinear absorption as the dominant optical limiting effect. Towards higher irradiation levels significant nonlinear scattering takes place as a secondary process. In contrast to 532 nm, at 1064 nm nonlinear scattering is less strong even at high irradiation levels and the nonlinear response is dominated by nonlinear absorption.

  9. Nonlinear synthetic aperture radar imaging using a harmonic radar

    NASA Astrophysics Data System (ADS)

    Gallagher, Kyle A.; Mazzaro, Gregory J.; Ranney, Kenneth I.; Nguyen, Lam H.; Martone, Anthony F.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2015-05-01

    This paper presents synthetic aperture radar (SAR) images of linear and nonlinear targets. Data are collected using a linear/nonlinear step frequency radar. We show that it is indeed possible to produce SAR images using a nonlinear radar. Furthermore, it is shown that the nonlinear radar is able to reduce linear clutter by at least 80 dB compared to a linear radar. The nonlinear SAR images also show the system's ability to detect small electronic devices in the presence of large linear clutter. The system presented here has the ability to completely ignore a 20-inch trihedral corner reflector while detecting a RF mixer with a dipole antenna attached.

  10. High power THz sources for nonlinear imaging

    SciTech Connect

    Tekavec, Patrick F.; Kozlov, Vladimir G.

    2014-02-18

    Many biological and chemical compounds have unique absorption features in the THz (0.1 - 10 THz) region, making the use of THz waves attractive for imaging in defense, security, biomedical imaging, and monitoring of industrial processes. Unlike optical radiation, THz frequencies can pass through many substances such as paper, clothing, ceramic, etc. with little attenuation. The use of currently available THz systems is limited by lack of highpower, sources as well as sensitive detectors and detector arrays operating at room temperature. Here we present a novel, high power THz source based on intracavity downconverison of optical pulses. The source delivers 6 ps pulses at 1.5 THz, with an average power of >300 μW and peak powers >450 mW. We propose an imaging method based on frequency upconverison that is ideally suited to use the narrow bandwidth and high peak powers produced by the source. By upconverting the THz image to the infrared, commercially available detectors can be used for real time imaging.

  11. Optical sparse aperture imaging.

    PubMed

    Miller, Nicholas J; Dierking, Matthew P; Duncan, Bradley D

    2007-08-10

    The resolution of a conventional diffraction-limited imaging system is proportional to its pupil diameter. A primary goal of sparse aperture imaging is to enhance resolution while minimizing the total light collection area; the latter being desirable, in part, because of the cost of large, monolithic apertures. Performance metrics are defined and used to evaluate several sparse aperture arrays constructed from multiple, identical, circular subapertures. Subaperture piston and/or tilt effects on image quality are also considered. We selected arrays with compact nonredundant autocorrelations first described by Golay. We vary both the number of subapertures and their relative spacings to arrive at an optimized array. We report the results of an experiment in which we synthesized an image from multiple subaperture pupil fields by masking a large lens with a Golay array. For this experiment we imaged a slant edge feature of an ISO12233 resolution target in order to measure the modulation transfer function. We note the contrast reduction inherent in images formed through sparse aperture arrays and demonstrate the use of a Wiener-Helstrom filter to restore contrast in our experimental images. Finally, we describe a method to synthesize images from multiple subaperture focal plane intensity images using a phase retrieval algorithm to obtain estimates of subaperture pupil fields. Experimental results from synthesizing an image of a point object from multiple subaperture images are presented, and weaknesses of the phase retrieval method for this application are discussed. PMID:17694146

  12. Nonlinear-optical, optical, and crystallographic properties of methyl p-hydroxybenzoate

    NASA Astrophysics Data System (ADS)

    Li, Zhengdong; Wu, Baichang; Su, Genbo

    1997-07-01

    Bulk crystals of methyl p-hydroxybenzoate were grown from organic solution. The crystal structure was determined by X-ray analysis. The refractive indices were determined by the method of prism minimum deviation. The nonlinear-optical coefficients dij and deff were measured. The nonlinear-optical properties are discussed in terms of crystalline structure.

  13. Nonlinear optical transmission in VOx nanotubes and VOx nanotube composites

    NASA Astrophysics Data System (ADS)

    Xu, J.-F.; Czerw, R.; Webster, S.; Carroll, D. L.; Ballato, J.; Nesper, R.

    2002-08-01

    Optical-limiting behavior of vanadium oxide nanotubes is characterized for the visible and infrared spectral ranges using 8 ns pulses from a Nd:YAG laser with an f/40 optical system. Vanadium oxide nanotube dispersions were investigated in both water suspensions and embedded in solid polymethyl methacrylate films. In each case, these nanotubes exhibit strong optical-limiting at 532 nm (in comparison to carbon nanotubes); however, no nonlinear behavior is observed for 1064 nm. This suggests that a two photon or excited state absorption mechanism is responsible for the observed nonlinearity.

  14. Nonlinear optical signal processing on multiwavelength sensitive materials.

    PubMed

    Azimipour, Mehdi; Pashaie, Ramin

    2013-11-01

    Exploiting salient features in the photodynamics of specific types of light sensitive materials, a new approach is presented for realization of parallel nonlinear operations with optics. We briefly review the quantum structure and mathematical models offered for the photodynamics of two multiwavelength sensitive materials, doped crystals of lithium niobate and thick layers of bacteriorhodopsin. Next, a special mode of these dynamics in each material is investigated and a graphical design procedure is offered to produce highly nonlinear optical responses that can be dynamically reshaped via applying minimum changes in the optical setup. PMID:24177084

  15. Laser-induced microwave generation with nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Borghesani, Francesco; Braggio, Caterina; Carugno, Giovanni; Della Valle, Federico; Ruoso, Giuseppe

    2014-05-01

    We report about a novel technique to generate microwave radiation by the irradiation of a nonlinear optical crystal with uniformly spaced, ultrashort optical pulses delivered by a mode-locked laser. We study systematically the laser polarization and intensity dependence of the microwave signal to conclusively show that it is a nonlinear phenomenon and that it originates from optical rectification. The measurements have been conducted using KTP, LBO and ZnSe crystals. The observed pulsed microwave signals are harmonically related to the laser pulses repetition rate, a feature that can be exploited to develop an innovative ultrafast laser detector.

  16. Synthesis and nonlinear optical absorption of novel chalcone derivative compounds

    NASA Astrophysics Data System (ADS)

    Rahulan, K. Mani; Balamurugan, S.; Meena, K. S.; Yeap, G.-Y.; Kanakam, Charles C.

    2014-03-01

    3-(4-(dimethylamino)phenyl)-1-(4-(4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl)phenyl)prop-2-en-1-one was synthesized and its third order nonlinear optical properties have been investigated using a z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear absorption behavior of the compound in chloroform presents a distinct difference at different laser intensity. Interestingly, the compound showed a switchover from saturable absorption (SA) to reverse saturable absorption (RSA) with the increase of excitation intensity. Our studies suggest that compound could be used as a potential candidate for optical device applications such as optical limiters.

  17. PT symmetry breaking and nonlinear optical isolation in coupled microcavities

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Chong, Y. D.

    2016-04-01

    We perform a theoretical study of nonlinear optical isolator devices based on coupled microcavities with gain and loss. Using coupled-mode theory, we derive a correspondence between the boundary of asymptotic stability in the nonlinear regime, where gain saturation is present, and the PT-breaking transition in the underlying linear system. For zero detuning and weak input intensity, the onset of optical isolation can be rigorously derived, and corresponds precisely to the PT transition point. When the couplings to the external ports are unequal, the isolation ratio exhibits an abrupt jump at the transition point, determined by the ratio of the couplings. This could be exploited to realize an actively controlled nonlinear optical isolator, in which strong optical isolation can be switched on or off using tiny variations in the inter-resonator separation.

  18. Integrated Optics for Planar imaging and Optical Signal Processing

    NASA Astrophysics Data System (ADS)

    Song, Qi

    Silicon photonics is a subject of growing interest with the potential of delivering planar electro-optical devices with chip scale integration. Silicon-on-insulator (SOI) technology has provided a marvelous platform for photonics industry because of its advantages in integration capability in CMOS circuit and countless nonlinearity applications in optical signal processing. This thesis is focused on the investigation of planar imaging techniques on SOI platform and potential applications in ultra-fast optical signal processing. In the first part, a general review and background introduction about integrated photonics circuit and planar imaging technique are provided. In chapter 2, planar imaging platform is realized by a silicon photodiode on SOI chip. Silicon photodiode on waveguide provides a high numerical aperture for an imaging transceiver pixel. An erbium doped Y2O3 particle is excited by 1550nm Laser and the fluorescent image is obtained with assistance of the scanning system. Fluorescence image is reconstructed by using image de-convolution technique. Under photovoltaic mode, we use an on-chip photodiode and an external PIN photodiode to realize similar resolution as 5μm. In chapter 3, a time stretching technique is developed to a spatial domain to realize a 2D imaging system as an ultrafast imaging tool. The system is evaluated based on theoretical calculation. The experimental results are shown for a verification of system capability to imaging a micron size particle or a finger print. Meanwhile, dynamic information for a moving object is also achieved by correlation algorithm. In chapter 4, the optical leaky wave antenna based on SOI waveguide has been utilized for imaging applications and extensive numerical studied has been conducted. and the theoretical explanation is supported by leaky wave theory. The highly directive radiation has been obtained from the broadside with 15.7 dB directivity and a 3dB beam width of ΔØ 3dB ≈ 1.65° in free space

  19. The optical nonlinearity of gold nanoparticles prepared by bioreduction method

    NASA Astrophysics Data System (ADS)

    Balbuena Ortega, A.; Arroyo Carrasco, M. L.; Gayou, V. L.; Orduña Díaz, A.; Delgado Macuil, R.; Rojas López, Marlon

    2013-11-01

    Nonlinear optical and electronic properties of nanosized metal particles have drawn considerable attention because of their strong and size-dependent plasmon resonance absorption. In a metal nanoparticle system such as gold dispersed in a transparent matrix, an absorption peak due to surface plasmon resonance is usually observed in the visible spectral region. Metal nanoparticles are of special interest as nonlinear materials for optical switching and computing because of their relatively large third-order nonlinearity (χ3) and ultrafast response time. The purpose of this study was to analyze the nonlinear optical properties of biosynthesized gold nanoparticles. The samples were prepared by biosynthesis method using yeast extract as reducing agent and the nonlinear optical properties of the nanoparticles were investigated using a single beam Z-scan technique with a beam power of 20 mW and operated at wavelength of 514 nm. The reaction between metal ions and yeast extracts were monitored by UV-visible spectra of Au nanoparticles in aqueous solution with different pH (3-6). The surface plasmon peak position was shifted from 528 nm to 573 nm, according to of pH variation 4 to 6. The average particle size was calculated by the absorption peak position using the Fernig method, from 42 to 103 nm. The z-scan curves showed a negative nonlocal nonlinear refractive index with a magnitude dependent on the nanoparticle size.

  20. Large Optical Nonlinearity Induced by Singlet Fission in Pentacene Films

    NASA Astrophysics Data System (ADS)

    Liu, Yunlong; Zhang, Chunfeng; Xiao, Min

    2015-03-01

    By creating two triplet excitons from one photo-excited singlet exciton, singlet fission in organic semiconductors has drawn tremendous attention for its potential application in boosting the efficiency of solar conversion. Here, we show that this carrier-multiplication effect can be used to dramatically improve the nonlinear optical response in organic materials. With the technique of dual-wavelength optical Kerr effect (OKE), we have observed large optical nonlinearity with a magnitude of χ (3) up to 10-9 esu in pentacene films, which is further shown to be a result of singlet fission as demonstrated by the detailed temporal dynamics and wavelength dependence experiment. Through the use of optical heterodyne detected OKE experiment, we have determined both the sign and value of Reχ (3) of the pentacene film. Such efficient third order nonlinear optical response has been successfully applied to demonstrate the all-optical switching. The results observed in this work indicate that the singlet fission could be served as an effective strategy to promote the optical nonlinearity in organic molecule systems. This work is supported by the National Basic Research Program of China (2013CB932903 and 2012CB921801, MOST), the National Science Foundation of China (91233103, 61108001, 11227406 and 11321063).

  1. Nonlinear nanoprobes for characterizing ultrafast optical near field

    NASA Astrophysics Data System (ADS)

    Li, Haifeng

    With the rapid development of ultrafast optics and nanophotonics, it is crucial to measure the spatiotemporal evolution of an ultrafast optical near field in nanometer spatial and femtosecond temporal resolution with minimal perturbation. Although near-field scanning optical microscopy (NSOM) can achieve nanoscale spatial resolution and various ultrashort pulse diagnostic tools can characterize femtosecond laser pulses, yet such capability to noninvasively characterize the nanoscale characteristics of femtosecond pulses in all three spatial dimensions remains elusive. In this dissertation, we developed different types of nonlinear optical probes to characterize ultrashort optical pulses. The nonlinear optical probe is composed of three parts, a silica fiber taper, a single nanowire bonded to the end of the fiber and nonlinear nanoparticles attached on the tip of the nanowire. The optical fiber taper can be readily mounted on a mechanical stage and served as a macroscopic interface for handling and positioning control. The single nanowire bridges the dimension gap between the nanocrystals and the fiber taper, and is critical for achieving large aspect ratio and hence minimizing optical scattering and perturbation. The nonlinear nanoparticles give rise to its capability to characterize ultrashort optical pulses. The unique fusion of nanoscale and nonlinear features in developed nonlinear optical probes provides the ability of probing ultrafast optical field in complex 3D microand nano- structures. The demonstration of such ability is crucial for understanding the interaction of ultrafast optical fields and nanoscale systems. The fabrication processes of the nonlinear optical probes are illustrated in detail and the optical properties of the probes are investigated. Two different types of nonlinear optical probes, two-photon fluorescent nanoprobes and Second HARmonic nanoProbes (SHARP), are fabricated. Interferometric autocorrelation measurements near the focal point

  2. Absorption-edge calculations of inorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Wu, Kechen; Chen, Chuangtian

    1992-03-01

    A theoretical model suitable for calculating absorption edges of inorganic nonlinear optical (NLO) crystals is introduced. This model is proved to be useful to elucidate the relationship between electronic structures of NLO-active groups and macroscopic properties of absorption edges on the UV side of most of the inorganic nonlinear optical crystals. A systematic calculation of absorption edges on the UV side for several important inorganic NLO crystals is carried out by means of DV-SCM-Xα method and all calculated results are in good agreement with experimental data. These inorganic NLO crystals include LiB3O5(LBO), β-BaB2O4(BBO), KB5, KDP, Na2SbF5, Ba2TiSi2O8, iodate and NaNO2. The calculated energy level structures of LiB3O5 and β-BaB2O4 crystals are compared with the measured XPS spectra. The unusual transparent spectra of KB5 and KDP crystals are partly explained from the microstructure point of view. The effect of lone electron pair in iodate and NaNO2 crystals on their absorption edges are discussed. All these results show that Anionic Group Theory of Nonlinear Optical Crystals is useful to evaluate the absorption edges of the inorganic nonlinear optical crystal and is a powerful tool in a Molecular Engineering approach to search for new nonlinear optical materials.

  3. Third-order nonlinear optical response of indigo carmine under 633 nm excitation for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Pramodini, S.; Poornesh, P.

    2014-11-01

    We report thermally induced third-order nonlinearity and optical limiting behaviour of Indigo Carmine dye. z-Scan technique was used to determine the sign and magnitude of absorptive and refractive nonlinearities. Continuous wave (CW) He-Ne laser operating at 633 nm was used as source of excitation. In open aperture z-scan experiments, samples exhibited reverse saturable absorption (RSA) process. For closed aperture z-scan experiments, samples revealed self-defocusing property. The presence of donor and acceptor groups in the structure increases the conjugation length and in turn increases the optical nonlinearity. Induced self-diffraction rings pattern was recorded for the samples and it is attributed to refractive index change and thermal lensing. Also, optical limiting and clamping studies were carried out for various input power. Optical clamping of about ~1 mW was observed. This endorses that the dye under investigation is a positive candidate for opto-electronic and photonic applications.

  4. Micro-optics for imaging.

    SciTech Connect

    Boye, Robert R.

    2010-09-01

    This project investigates the fundamental imaging capability of an optic with a physical thickness substantially less than 1 mm. The analysis assumes that post-processing can overcome certain restrictions such as detector pixel size and image degradation due to aberrations. A first order optical analysis quickly reveals the limitations of even an ideal thin lens to provide sufficient image resolution and provides the justification for pursuing an annular design. Some straightforward examples clearly show the potential of this approach. The tradeoffs associated with annular designs, specifically field of view limitations and reduced mid-level spatial frequencies, are discussed and their impact on the imaging performance evaluated using several imaging examples. Additionally, issues such as detector acceptance angle and the need to balance aberrations with resolution are included in the analysis. With these restrictions, the final results present an excellent approximation of the expected performance of the lens designs presented.

  5. Nonlinear image labeling for multivalued segmentation.

    PubMed

    Dellepiane, S G; Fontana, F; Vernazza, G L

    1996-01-01

    We describe a framework for multivalued segmentation and demonstrate that some of the problems affecting common region-based algorithms can be overcome by integrating statistical and topological methods in a nonlinear fashion. We address the sensitivity to parameter setting, the difficulty with handling global contextual information, and the dependence of results on analysis order and on initial conditions. We develop our method within a theoretical framework and resort to the definition of image segmentation as an estimation problem. We show that, thanks to an adaptive image scanning mechanism, there is no need of iterations to propagate a global context efficiently. The keyword multivalued refers to a result property, which spans over a set of solutions. The advantage is twofold: first, there is no necessity for setting a priori input thresholds; secondly, we are able to cope successfully with the problem of uncertainties in the signal model. To this end, we adopt a modified version of fuzzy connectedness, which proves particularly useful to account for densitometric and topological information simultaneously. The algorithm was tested on several synthetic and real images. The peculiarities of the method are assessed both qualitatively and quantitatively. PMID:18285129

  6. Complex geometrical optics of inhomogeneous and nonlinear saturable media

    NASA Astrophysics Data System (ADS)

    Berczynski, Pawel

    2013-05-01

    The method of complex geometrical optics (CGO) is presented, which describes Gaussian beam (GB) diffraction and self-focusing along curvilinear trajectory in smoothly inhomogeneous and nonlinear saturable media. CGO method reduces the problem of Gaussian beam propagation in inhomogeneous and nonlinear media to the system of the first order ordinary differential equations for the complex curvature of the wave front and for GB amplitude, which can be readily solved both analytically and numerically. As a result, CGO radically simplifies the description of Gaussian beam diffraction and self-focusing effects as compared to the other methods of nonlinear optics such as: variational method approach, method of moments and beam propagation method. The power of CGO method is presented on the example of the evolution of beam intensity and wave front cross-section along curvilinear central ray with torsion in weakly absorptive and nonlinear saturable graded-index fiber, where the effect of initial beam ellipticity is included into our description.

  7. Synthesis of polycarbonates containing nonlinear optical chromophores

    SciTech Connect

    Moore, C.G.; Brittain, W.J.

    1995-12-31

    A new nonlinear (NLO) chromophore has been prepared. The chromophore is similar in structure to DANS (N,N-dimethylamino-4-nitrostilbene), but includes bisphenol moities. The bisphenol structure makes this system an excellent candidate for cyclic polycarbonate chemistry. The ring-opening polymerization of cyclic precursors containing NLO chromophore provides a novel processing pathway to NLO polymers.

  8. Broadband optical limiting and nonlinear optical absorption properties of a novel hyperbranched conjugated polymer

    NASA Astrophysics Data System (ADS)

    Li, Chao; Liu, Chunling; Li, Quanshui; Gong, Qihuang

    2004-12-01

    The nonlinear transmittance of a novel hyperbranched conjugated polymer named DMA-HPV has been measured in CHCl 3 solution using a nanosecond optical parametric oscillator. DMA-HPV shows excellent optical limiting performance in the visible region from 490 to 610 nm. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its huge and broadband nonlinear optical absorption.

  9. Resonant-type third-order optical nonlinearity and optical bandgap in multicomponent oxide glasses

    SciTech Connect

    El-Diasty, Fouad; Abdel-Baki, Manal; Bakry, Assem M.

    2009-05-01

    Optical nonlinearity or the nonlinear hyperpolarizability of amorphous materials (e.g., glasses) is related directly to the complex third-order susceptibility. The imaginary part of third-order susceptibility affects negatively the maximum data rate in telecommunication systems. In addition, many transition metals containing glasses have bandgaps with semiconductor-like behavior. So, due to the necessity of operation near the absorption band edge, the study of optical nonlinearity and band structure in glasses is very essential. In this work, we investigated the relationship between the imaginary third-order nonlinear susceptibility and the bandgap of some different series of prepared oxide glasses. A universal empirical formula is given to correlate the imaginary part of the third-order nonlinear susceptibility of the glasses and their optical bandgaps. The obtained nonlinearity is discussed in view of available theories and mechanisms.

  10. Nonlinear optical behavior of porphyrin functionalized nanodiamonds: an efficient material for optical power limiting.

    PubMed

    Muller, Olivier; Pichot, Vincent; Merlat, Lionel; Schmidlin, Loic; Spitzer, Denis

    2016-05-10

    The nonlinear optical mechanisms and the optical limiting behavior of porphyrin functionalized detonation nanodiamonds are investigated and compared to the conventional detonation nanodiamonds (DNDs). The optical limiting behavior is characterized by means of nonlinear transmittance, Z-scan, and scattered intensity measurements when submitted to a nanosecond pulsed Nd:YAG laser operating at the second harmonic wavelength. We found that the largest nonlinear attenuation was observed on the 4,4',4'',4'''-(porphyrin-5, 10, 15, 20-tetrayl) tetrakis benzoic acid (PCOOH) suspension. Using Z-scan experiments, it is shown that nonlinear refraction predominates in the unfunctionalized DND suspension, while nonlinear absorption is the most relevant mechanism in the porphyrin functionalized DNDs. Furthermore, a stronger backscattered intensity signal is highlighted for the unfunctionalized DNDs through nonlinear scattering measurements. PMID:27168296

  11. Theoretical studies for novel non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Wu, Kechen; Chen, Chuangtian

    1996-09-01

    To fulfil the "molecular engineering" of non-linear optical crystals, two theoretical models suitable respectively for the studies of the absorption edge and birefringence of a non-linear optical crystal have been set up. Molecular quantum chemical methods have been adopted in the systematic calculations of some typical crystals. DV-SCM-X α methods have been used to calculate the absorption edge on the UV side of BBO, LBO, KB5, KDP, Na 2SbF 5, Ba 2TiSi 2O 8, iodate and NaNO 2 crystals. Ab initio methods have been adopted to study the birefringence of NaNO 2, BBO, LiIO 3 and urea crystals. All the theoretical results agreed well with the experimental values. The relationship between structure and properties has been discussed. The results will be helpful to the search for novel non-linear optical crystals.

  12. Numerical simulation of the nonlinear optical response of bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Kowalski, Gregory J.

    1996-10-01

    The numerical simulation of the nonlinear optical behavior of bacteriorhodopsin in a solution of water is described. Relationships for the intensity dependent absorption coefficient and index of refraction are developed and used in the numerical simulation of bacteriorhodopsin as an optical limiter and as defocussing element for laser pulses in the picosecond regime. The algorithm is a transient finite volume method that is coupled with a 'ray model' of the radiation which simultaneously solves the heat transfer and Maxwell's equations. The nonlinear behavior of the material is included in this analysis using a modified Euler predictor-corrector integration technique. Calculated power limiting and z-scan curves are in qualitative agreement with experiments. These results indicate that the code can be used to investigate and optimize optical systems which use the nonlinear behavior of bacteriorhodopsin.

  13. Large optical nonlinearity induced by singlet fission in pentacene films.

    PubMed

    Liu, Yunlong; Zhang, Chunfeng; Wang, Rui; Zhang, Bo; Tan, Zhanao; Wang, Xiaoyong; Xiao, Min

    2015-05-18

    By creating two triplet excitons from one photo-excited singlet exciton, singlet fission in organic semiconductors has drawn tremendous attention for its potential applications in boosting the efficiency of solar conversion. Here, we show that this carrier-multiplication effect can also be used to dramatically improve the nonlinear optical response in organic materials. We have observed large optical nonlinearity with a magnitude of χ((3)) up to 10(-9) esu in pentacene films, which is further shown to be a result of singlet fission by monitoring the temporal dynamics. The potential application of such efficient nonlinear optical response has been demonstrated with a singlet-fission-induced polarization rotation. PMID:25845461

  14. Photoconductive and nonlinear optical properties of composites based on metallophthalocyanines

    NASA Astrophysics Data System (ADS)

    Vannikov, A. V.; Grishina, A. D.; Gorbunova, Yu. G.; Tsivadze, A. Yu.

    2015-08-01

    The photoconductive, photorefractive and nonlinear optical properties of composites from polyvinylcarbazole or aromatic polyimide containing supramolecular ensembles of (tetra-15-crown-5) - phthalocyaninato gallium, indium, - phthalocyaninateacetato yttrium, - phthalocyaninato ruthenium with axially coordinated pyrazine molecules were investigated at 633, 1030 and 1064nmusing continuous and pulsed lasers. Supramolecular ensembles (SE) were prepared through dissolution of molecular metallophthalocyanines in tetrachloroethane (TCE) and subsequent treatment via three cycles of heating to 90∘C and slow cooling to room temperature. The zscan method in femtosecond and nanosecond regimeswas used for measuring nonlinear optical properties phthalocyaninato indium and yttrium in TCE solutions and polymer films. It was established that effect of heavy metallic atom is basic factor which determines the quantum yield, photorefractive amplification of laser object beam, dielectric susceptibility of third order and nonlinear optical properties of metallophthalocyanines.

  15. Solvent effects on the nonlinear optical responses of anil derivatives

    NASA Astrophysics Data System (ADS)

    Plaquet, Aurélie; Bogdan, Elena; Antonov, Liudmil; Rodriguez, Vincent; Ducasse, Laurent; Champagne, Benoıît; Castet, Frédéric

    2015-01-01

    This contribution addresses the solvent effects on the second-order nonlinear optical responses of three representative anil derivatives, and in particular on their variations upon switching between the enol-imine and keto-amine forms. The impact of solute-solvent interactions is investigated by means of ab initio and DFT calculations in which solvent effects are included through the polarizable continuum model. In addition, for one of the compounds, Hyper-Rayleigh Scattering experiments and ab initio calculations are combined to highlight the impact of the solvent-induced equilibrium displacement. These studies show that the global solvent effect on the nonlinear optical responses originates from both the displacement of the tautomeric equilibrium and from the modification of the second-order nonlinear optical response of the individual tautomeric forms.

  16. Fiber optic snapshot hyperspectral imager

    NASA Astrophysics Data System (ADS)

    Mansur, David J.; Rentz Dupuis, Julia; Vaillancourt, Robert

    2012-06-01

    OPTRA is developing a snapshot hyperspectral imager (HSI) employing a fiber optic bundle and dispersive spectrometer. The fiber optic bundle converts a broadband spatial image to an array of fiber columns which serve as multiple entrance slits to a prism spectrometer. The dispersed spatially resolved spectra are then sampled by a two-dimensional focal plane array (FPA) at a greater than 30 Hz update rate, thereby qualifying the system as snapshot. Unlike snapshot HSI systems based on computed tomography or coded apertures, our approach requires only the remapping of the FPA frame into hyperspectral cubes rather than a complex reconstruction. Our system has high radiometric efficiency and throughput supporting sufficient signal to noise for hyperspectral imaging measurements made over very short integration times (< 33 ms). The overall approach is compact, low cost, and contains no moving parts, making it ideal for unmanned airborne surveillance. In this paper we present a preliminary design for the fiber optic snapshot HSI system.

  17. Optical phase conjugation in third-order nonlinear photonic crystals

    SciTech Connect

    Xie Ping; Zhang Zhaoqing

    2004-05-01

    We predict that the efficiency of the optical phase conjugation generation can be enhanced by more than four orders of magnitude in a {chi}{sup (3)} nonlinear superlattice, as compared with that in a homogeneous nonlinear medium of the same sample thickness and {chi}{sup (3)} nonlinearity. Such an effective enhancement utilizes the localized properties of the fields inside the sample at the band-edge state, gap-soliton state, or defect state. Due to the presence of feedback mechanism at each interface of a superlattice, we also predict that the phase conjugation can still be effectively generated when only one pump wave is used.

  18. Nonlinear optical Galton board: Thermalization and continuous limit

    NASA Astrophysics Data System (ADS)

    Di Molfetta, Giuseppe; Debbasch, Fabrice; Brachet, Marc

    2015-10-01

    The nonlinear optical Galton board (NLOGB), a quantum walk like (but nonlinear) discrete time quantum automaton, is shown to admit a complex evolution leading to long time thermalized states. The continuous limit of the Galton board is derived and shown to be a nonlinear Dirac equation (NLDE). The (Galerkin-truncated) NLDE evolution is shown to thermalize toward states qualitatively similar to those of the NLOGB. The NLDE conserved quantities are derived and used to construct a stochastic differential equation converging to grand canonical distributions that are shown to reproduce the (microcanonical) NLDE thermalized statistics. Both the NLOGB and the Galerkin-truncated NLDE are thus demonstrated to exhibit spontaneous thermalization.

  19. Modulation instability of optical nonlinear media: a route to chaos

    NASA Astrophysics Data System (ADS)

    Sharif, Morteza A.

    2011-12-01

    Modulation Instability is known as intrinsic property of a nonlinear medium like Kerr medium or photorefractive medium; through the such media, the system behavior is possible to transit form stationary regime to chaotic regime; this paper deals with Modulation Instability (MI) in a nonlinear medium and investigates the analogy of MI of optical nonlinear medium and the consequent chaotic regime based on extracting Lyapunov exponent through the power spectrum and equivalently intensity-time diagram of MI; the experimental observation truly confirms the results of MI as the route to the chaotic regime.

  20. From Ewald sphere to Ewald shell in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Huang, Huang; Huang, Cheng-Ping; Zhang, Chao; Hong, Xu-Hao; Zhang, Xue-Jin; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-07-01

    Ewald sphere is a simple vector scheme to depict the X-ray Bragg diffraction in a crystal. A similar method, known as the nonlinear Ewald sphere, was employed to illustrate optical frequency conversion processes. We extend the nonlinear Ewald sphere to the Ewald shell construction. With the Ewald shell, a variety of quasi-phase-matching (QPM) effects, such as the collective envelope effect associated with multiple QPM resonances, the enhanced second- harmonic generation due to multiple reciprocal vectors etc., are suggested theoretically and verified experimentally. By rotating the nonlinear photonic crystal sample, the dynamic evolution of these QPM effects has also been observed, which agreed well with the Ewald shell model.

  1. Optics in a nonlinear gravitational plane wave

    NASA Astrophysics Data System (ADS)

    Harte, Abraham I.

    2015-09-01

    Gravitational waves can act like gravitational lenses, affecting the observed positions, brightnesses, and redshifts of distant objects. Exact expressions for such effects are derived here in general relativity, allowing for arbitrarily-moving sources and observers in the presence of plane-symmetric gravitational waves. At least for freely falling sources and observers, it is shown that the commonly-used predictions of linear perturbation theory can be generically overshadowed by nonlinear effects; even for very weak gravitational waves, higher-order perturbative corrections involve secularly-growing terms which cannot necessarily be neglected when considering observations of sufficiently distant sources. Even on more moderate scales where linear effects remain at least marginally dominant, nonlinear corrections are qualitatively different from their linear counterparts. There is a sense in which they can, for example, mimic the existence of a third type of gravitational wave polarization.

  2. Optimization of microscopic and macroscopic second order optical nonlinearities

    NASA Technical Reports Server (NTRS)

    Marder, Seth R.; Perry, Joseph W.

    1993-01-01

    Nonlinear optical materials (NLO) can be used to extend the useful frequency range of lasers. Frequency generation is important for laser-based remote sensing and optical data storage. Another NLO effect, the electro-optic effect, can be used to modulate the amplitude, phase, or polarization state of an optical beam. Applications of this effect in telecommunications and in integrated optics include the impression of information on an optical carrier signal or routing of optical signals between fiber optic channels. In order to utilize these effects most effectively, it is necessary to synthesize materials which respond to applied fields very efficiently. In this talk, it will be shown how the development of a fundamental understanding of the science of nonlinear optics can lead to a rational approach to organic molecules and materials with optimized properties. In some cases, figures of merit for newly developed materials are more than an order of magnitude higher than those of currently employed materials. Some of these materials are being examined for phased-array radar and other electro-optic switching applications.

  3. Reduction of nonlinear phase noise using optical phase conjugation in quasi-linear optical transmission systems.

    PubMed

    Kumar, Shiva; Liu, Ling

    2007-03-01

    An analytical expression for the variance of nonlinear phase noise for a quasi-linear system using the midpoint optical phase conjugation (OPC) is obtained. It is shown that the the system with OPC and dispersion inversion (DI) can exactly cancel the nonlinear phase noise up to the first order in nonlinear coefficient if the amplifier and the end point of the system are equidistant from the OPC. It is found that the nonlinear phase noise variance of the midpoint phase-conjugated optical transmission system with DI is smaller than that of the system without DI. PMID:19532453

  4. Anomalous nonlinear absorption in epsilon-near-zero materials: optical limiting and all-optical control.

    PubMed

    Vincenti, M A; de Ceglia, D; Scalora, Michael

    2016-08-01

    We investigate nonlinear absorption in films of epsilon-near-zero materials. The combination of large local electric fields at the fundamental frequency and material losses at the harmonic frequencies induce unusual intensity-dependent phenomena. We predict that the second-order nonlinearity of a low-damping, epsilon-near-zero slab produces an optical limiting effect that mimics a two-photon absorption process. Anomalous absorption profiles that depend on low permittivity values at the pump frequency are also predicted for third-order nonlinearities. These findings suggest new opportunities for all-optical light control and novel ways to design reconfigurable and tunable nonlinear devices. PMID:27472631

  5. Nonlinear optical measurements of glucose concentration

    NASA Astrophysics Data System (ADS)

    Yakovlev, V. V.

    2008-02-01

    Diabetes mellitus is a metabolic disease that currently affects about 7% of the US population, or roughly about 20 million people. Effectively controlling diabetes requires regular measurements of the blood sugar levels to ensure the one time insulin injection when the concentration of glucose reaches a critical level. In this report, nonlinear Raman microspectroscopy is demonstrated to be a promising new way of continuous and noninvasive way of measuring the glucose concentration.

  6. Linear and nonlinear Zeno effects in an optical coupler

    SciTech Connect

    Abdullaev, F. Kh.; Konotop, V. V.; Shchesnovich, V. S.

    2011-04-15

    It is shown that, in a simple coupler where one of the waveguides is subject to controlled losses of the electric field, it is possible to observe an optical analog of the linear and nonlinear quantum Zeno effects. The phenomenon consists in a counterintuitive enhancement of transparency of the coupler with an increase of the dissipation and represents an optical analog of the quantum Zeno effect. Experimental realization of the phenomenon based on the use of chalcogenide glasses is proposed. The system allows for observation of the crossover between the linear and nonlinear Zeno effects, as well as the effective manipulation of light transmission through the coupler.

  7. Non-Markovianity: initial correlations and nonlinear optical measurements

    PubMed Central

    Dijkstra, Arend G.; Tanimura, Yoshitaka

    2012-01-01

    By extending the response function approach developed in nonlinear optics, we analytically derive an expression for the non-Markovianity in the time evolution of a system in contact with a quantum mechanical bath, and find a close connection with the directly observable nonlinear optical response. The result indicates that memory in the bath-induced fluctuations rather than in the dissipation causes non-Markovianity. Initial correlations between states of the system and the bath are shown to be essential for a correct understanding of the non-Markovianity. These correlations are included in our treatment through a preparation function. PMID:22753819

  8. Photocrosslinkable copolymers for non-linear optical applications

    SciTech Connect

    Kawatsuki, N.; Pakbaz, K.; Schmidt, H.W.

    1993-12-31

    New photocrosslinkable copolymers have been synthesized and applied as non-linear optical materials. The copolymers are based on methyl methacrylate, a photo-excitable benzophenone monomer, a non-linear optical active 4`-[(2-hydroxyethyl)ethylamino]-4-nitro-azobenzene (disperse red 1) side chain monomer and a crosslinkable 2-butenyl monomer. These copolymers can be crosslinked by UV light at 366 nm in the poled state and show a stable alignment of NLO chromophore by monitoring the adsorption spectra. The crosslinked and poled film did not change its alignment after storing 4 weeks at room temperature.

  9. Optically detected magnetic resonance imaging

    SciTech Connect

    Blank, Aharon; Shapiro, Guy; Fischer, Ran; London, Paz; Gershoni, David

    2015-01-19

    Optically detected magnetic resonance provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging techniques. Here, we demonstrate how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially encode the sample. This result in what we denote as an 'optically detected magnetic resonance imaging' technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importance in the field of quantum spin-based devices and sensors.

  10. Nonlinear optical propagation in a tandem structure comprising nonlinear absorption and scattering materials

    SciTech Connect

    Wang, Kangpeng; Ju, Yongfeng; He, Jin; Zhang, Long E-mail: lzhang@siom.ac.cn; Wang, Jun E-mail: lzhang@siom.ac.cn; Chen, Yu; Blau, Werner J.

    2014-01-13

    Laser propagation in a tandem structure comprising carbon nanotubes and phthalocyanines is studied by Z-scan method. Due to the different mechanisms of the two materials, the laser beam can be attenuated with different absorptivities, by changing the sequence of light passing through each material. Numerical simulations considering the effect of path length and the change of nonlinear coefficient within each material are conducted for understanding the distribution of laser intensity in the tandem system and hence, fitting of the asymmetric Z-scan curves. The results are helpful for the design of nonlinear optical devices comprising multiple nonlinear materials and mechanisms.

  11. A robust nonlinear filter for image restoration.

    PubMed

    Koivunen, V

    1995-01-01

    A class of nonlinear regression filters based on robust estimation theory is introduced. The goal of the filtering is to recover a high-quality image from degraded observations. Models for desired image structures and contaminating processes are employed, but deviations from strict assumptions are allowed since the assumptions on signal and noise are typically only approximately true. The robustness of filters is usually addressed only in a distributional sense, i.e., the actual error distribution deviates from the nominal one. In this paper, the robustness is considered in a broad sense since the outliers may also be due to inappropriate signal model, or there may be more than one statistical population present in the processing window, causing biased estimates. Two filtering algorithms minimizing a least trimmed squares criterion are provided. The design of the filters is simple since no scale parameters or context-dependent threshold values are required. Experimental results using both real and simulated data are presented. The filters effectively attenuate both impulsive and nonimpulsive noise while recovering the signal structure and preserving interesting details. PMID:18290007

  12. Retinal Optical Coherence Tomography Imaging

    NASA Astrophysics Data System (ADS)

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in

  13. Programmable Iterative Optical Image And Data Processing

    NASA Technical Reports Server (NTRS)

    Jackson, Deborah J.

    1995-01-01

    Proposed method of iterative optical image and data processing overcomes limitations imposed by loss of optical power after repeated passes through many optical elements - especially, beam splitters. Involves selective, timed combination of optical wavefront phase conjugation and amplification to regenerate images in real time to compensate for losses in optical iteration loops; timing such that amplification turned on to regenerate desired image, then turned off so as not to regenerate other, undesired images or spurious light propagating through loops from unwanted reflections.

  14. Nonlinear optical properties and optical power limiting effect of Giemsa dye

    NASA Astrophysics Data System (ADS)

    Al-Saidi, Imad Al-Deen Hussein A.; Abdulkareem, Saif Al-Deen

    2016-08-01

    The nonlinear optical properties of Giemsa dye in chloroform solution for different concentrations and dye mixed with poly(methylmethacrylate) (PMMA) as a dye-doped polymer film were investigated using continuous wave (CW) low power solid-state laser (SSL) operating at wavelength of 532 nm as an excitation source. Using the single beam z-scan technique, the nonlinear refractive index (n2), the nonlinear absorption coefficient (β), and the third-order nonlinear optical susceptibility (χ(3)) of Giemsa dye were measured. The measurements reveal that both n2 and β are dependent on the dye concentration. The obtained results indicate that the Giemsa dye exhibits positive nonlinear saturable absorption (SA) and negative refraction nonlinearity, manifestation of self-defocusing effect. Optical power limiting characteristics of the Giemsa dye at different concentrations in solution and polymer film were studied. The observed large third-order optical nonlinearity of Giemsa dye confirms that Giemsa dye is a promising nonlinear material for the optical power limiting and photonic devices applications.

  15. Nonlinear optics, active plasmonics and metamaterials with liquid crystals

    NASA Astrophysics Data System (ADS)

    Khoo, Iam Choon

    2014-03-01

    Nematic liquid crystals possess large and versatile optical nonlinearities suitable for photonics applications spanning the femtoseconds to milliseconds time scales, and across a wide spectral window. We present a comprehensive review of the physical properties and mechanisms that underlie these multiple time scales nonlinearities, delving into individual molecular electronic responses as well as collective ordered-phase dynamical processes. Several exemplary theoretical formalisms and feasibility demonstrations of ultrafast all-optical transmission switching and tunable metamaterials and plasmonic photonic structures where the liquid crystal constituents play the critical role of enabling the processes are discussed. Emphasis is placed on all-optical processes, but we have also highlighted cases where electro-optical means could provide additional control, flexibility and enhancement possibility. We also point out how another phase of chiral nematic, namely, Blue-Phase liquid crystals could circumvent some of the limitations of nematic and present new possibilities.

  16. Nonlinear Optics of Intense Attosecond Light Pulses

    NASA Astrophysics Data System (ADS)

    Nazarkin, Alexander

    2006-10-01

    The interaction of an intense light pulse of "subatomic" duration with a system of multiple discrete quantum states is analyzed. The nonperturbative character of the response to the pulse field leading to an efficient conversion into high order harmonics is predicted. The spatial-temporal evolution of the field is shown to obey a generalized nonlinear wave equation of the double-sine-Gordon type. In addition to the solitary wave structures, it predicts a nontrivial regime of pulse amplification accompanied by extreme temporal self-contraction of the amplified field.

  17. Nonlinear optics and crystalline whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey B.; Savchenkov, Anatoliy A.; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode (WGM) crystalline resonators, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics. In particular, we demonstrate experimentally a tunable third-order optical filter fabricated from the three metalized resonators; and report observation of parametric frequency dobuling in a WGM resonator made of periodically poled lithium niobate (PPLN).

  18. Soliton transmission in optical fibers with loss and saturable nonlinearity

    NASA Astrophysics Data System (ADS)

    Aicklen, Gregory H.; Tamil, Lakshman S.

    1996-09-01

    Optical solitons propagating in media exhibiting saturable nonlinearity offer advantages over Kerr-medium solitons for transmission over large distances through optical fibers with loss. Soliton pulses in saturable media offer greater energy for a given peak power, and upper-branch solitons decrease in width with distance traveled. These properties result in pulses that remain distinct and detectable for greater distances than Kerr-medium solitons do with the same peak power. .

  19. Nonlinear optical properties of potential sensitive styryl dyes.

    PubMed Central

    Huang, J Y; Lewis, A; Loew, L

    1988-01-01

    The nonlinear optical properties of dyes that alter their optical characteristics rapidly with membrane potential are described. The second harmonic signals from these dyes characterized in this paper are among the largest that have been detected to date. Structural conclusions are drawn from the second harmonic signals generated by the Langmuir Blodgett monolayers used in these measurements. Our results indicate that with appropriate instrumentation second harmonic signals could readily be detected from living cells stained with these dyes. PMID:3390517

  20. Hadamard multimode optical imaging transceiver

    SciTech Connect

    Cooke, Bradly J; Guenther, David C; Tiee, Joe J; Kellum, Mervyn J; Olivas, Nicholas L; Weisse-Bernstein, Nina R; Judd, Stephen L; Braun, Thomas R

    2012-10-30

    Disclosed is a method and system for simultaneously acquiring and producing results for multiple image modes using a common sensor without optical filtering, scanning, or other moving parts. The system and method utilize the Walsh-Hadamard correlation detection process (e.g., functions/matrix) to provide an all-binary structure that permits seamless bridging between analog and digital domains. An embodiment may capture an incoming optical signal at an optical aperture, convert the optical signal to an electrical signal, pass the electrical signal through a Low-Noise Amplifier (LNA) to create an LNA signal, pass the LNA signal through one or more correlators where each correlator has a corresponding Walsh-Hadamard (WH) binary basis function, calculate a correlation output coefficient for each correlator as a function of the corresponding WH binary basis function in accordance with Walsh-Hadamard mathematical principles, digitize each of the correlation output coefficient by passing each correlation output coefficient through an Analog-to-Digital Converter (ADC), and performing image mode processing on the digitized correlation output coefficients as desired to produce one or more image modes. Some, but not all, potential image modes include: multi-channel access, temporal, range, three-dimensional, and synthetic aperture.

  1. Optical Nonlinearities in Semiconductor Doped Glass Channel Waveguides.

    NASA Astrophysics Data System (ADS)

    Banyai, William Charles

    The nonlinear optical properties of a semiconductor -doped glass (SDG) channel waveguide were measured on a picosecond time-scale; namely, fluence-dependent changes in the absorption and the refractive index as well as the relaxation time of the nonlinearity. Slower, thermally -induced changes in the refractive index were also observed. The saturation of the changes in the absorption and the refractive index with increasing optical fluence is explained using a plasma model with bandfilling as the dominant mechanism. The fast relaxation time of the excited electron-hole plasma (20 ps) is explained using a surface-state recombination model. A figure of merit for a nonlinear directional coupler fabricated in a material with a saturable nonlinear refractive index is presented. The measured nonlinear change in the refractive index of the SDG saturates below the value required to effect fluence-dependent switching in a nonlinear directional coupler. Experiments with a channel-waveguide directional coupler support this prediction. However, absorption switching due to differential saturation of the absorption in the two arms of the directional coupler was observed.

  2. Nonlinear processes in multi-mode optical fibers

    NASA Astrophysics Data System (ADS)

    Pourbeyram Kaleibar, Hamed

    Nonlinear processes in optical fibers can affect data transmission and power carried by optical fibers and can limit the bandwidth and the capacity of optical communications. On the other hand nonlinear phenomena could be utilized to build in-fiber all-optical light sources and amplifiers. In this thesis new peaks inside an optical fiber have been generated using nonlinear processes. An intense green pump laser has been launched into a short fiber and specific modes have been excited to generate two new peaks in red and blue wavelengths, where two pump photons are annihilated to create two new photons in red and blue. The generated peaks are shifted far from pump; therefore they are less polluted by pump and Raman induced noises. The phase matching condition and the photon-flux rate for spontaneous and stimulated FWM have been studied both theoretically and experimentally for a commercial grade SMF-28 fiber. In low power and spontaneous regime new peaks are generated from quantum vacuum noise. Using the same pump laser for a long fiber, up to 21 new peaks spanning from green to Infrared have been generated. These peaks are equally spaced by 13THz. Generation of a Raman cascade spanning the wavelength range of 523 to 1750 nm wavelength range, in a standard telecommunication graded-index multimode optical fiber has been reported. Despite the highly multimode nature of the pump, the Raman peaks are generated in specific modes of the fiber, confirming substantial beam cleanup during the stimulated Raman scattering process.

  3. 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. PMID:26565262

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

    NASA Astrophysics Data System (ADS)

    de Melo, P. B.; Nunes, A. M.; Omena, L.; Nascimento, S. M. S. do; 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.

  5. CARS and non-linear microscopy imaging of brain tumors

    NASA Astrophysics Data System (ADS)

    Galli, Roberta; Uckermann, Ortrud; Tamosaityte, Sandra; Geiger, Kathrin; Schackert, Gabriele; Steiner, Gerald; Koch, Edmund; Kirsch, Matthias

    2013-06-01

    Nonlinear optical microscopy offers a series of techniques that have the potential to be applied in vivo, for intraoperative identification of tumor border and in situ pathology. By addressing the different content of lipids that characterize the tumors with respect to the normal brain tissue, CARS microscopy enables to discern primary and secondary brain tumors from healthy tissue. A study performed in mouse models shows that the reduction of the CARS signal is a reliable quantity to identify brain tumors, irrespective from the tumor type. Moreover it enables to identify tumor borders and infiltrations at a cellular resolution. Integration of CARS with autogenous TPEF and SHG adds morphological and compositional details about the tissue. Examples of multimodal CARS imaging of different human tumor biopsies demonstrate the ability of the technique to retrieve information useful for histopathological diagnosis.

  6. Nonlinear common-path interferometer: an image processor.

    PubMed

    Treviño-Palacios, Carlos Gerardo; Iturbe-Castillo, Marcelo David; Sánchez-de-la-Llave, David; Ramos-García, Ruben; Olivos-Pérez, Luis Ignacio

    2003-09-01

    A single-lens optical setup with a nonlinear medium placed in its geometrical focal plane is used to contrast a phase disturbance. This setup blends the robustness of phase-contrast methods with an optical nonlinear intensity-dependent medium and the usefulness of traditional interferometric techniques. We show that the ratio of the total illumination area to the phase-object area determines an adequate phase-disturbance contrast. PMID:12962385

  7. Optomechanical Enhancement of Doubly Resonant 2D Optical Nonlinearity.

    PubMed

    Yi, Fei; Ren, Mingliang; Reed, Jason C; Zhu, Hai; Hou, Jiechang; Naylor, Carl H; Johnson, A T Charlie; Agarwal, Ritesh; Cubukcu, Ertugrul

    2016-03-01

    Emerging two-dimensional semiconductor materials possess a giant second order nonlinear response due to excitonic effects while the monolayer thickness of such active materials limits their use in practical nonlinear devices. Here, we report 3300 times optomechanical enhancement of second harmonic generation from a MoS2 monolayer in a doubly resonant on-chip optical cavity. We achieve this by engineering the nonlinear light-matter interaction in a microelectro-mechanical system enabled optical frequency doubling device based on an electrostatically tunable Fabry-Perot microresonator. Our versatile optomechanical approach will pave the way for next generation efficient on-chip tunable light sources, sensors, and systems based on molecularly thin materials. PMID:26854706

  8. Photonic quantum transport in a nonlinear optical fiber

    NASA Astrophysics Data System (ADS)

    Hafezi, M.; Chang, D. E.; Gritsev, V.; Demler, E. A.; Lukin, M. D.

    2011-06-01

    We theoretically study the transmission of few-photon quantum fields through a strongly nonlinear optical medium. We develop a general approach to investigate nonequilibrium quantum transport of bosonic fields through a finite-size nonlinear medium and apply it to a recently demonstrated experimental system where cold atoms are loaded in a hollow-core optical fiber. We show that when the interaction between photons is effectively repulsive, the system acts as a single-photon switch. In the case of attractive interaction, the system can exhibit either antibunching or bunching, associated with the resonant excitation of bound states of photons by the input field. These effects can be observed by probing statistics of photons transmitted through the nonlinear fiber.

  9. Syntheses of Octasubstituted Metal Phthalocyanines for Nonlinear Optics

    NASA Technical Reports Server (NTRS)

    Guo, Huaisong; Townsend, Cheryl; Sanghadasa, Mohan; Amai, Robert L. S.; Clark, Ronald D.; Penn, Benjamin

    1998-01-01

    Many organic materials can be used as nonlinear optical media. Phthalocyanines are of special interest because they show an unusually large third order nonlinear response, they are thermally and photochemically stable and they can be formed into oriented thin films (Langmuir-Blodgett films). They also can be easily complexed by a large variety of metals, which place them at the interface between organics and organometallics, and allows for fine tuning of the macro cycle electronic properties by the coordinated metal and substituent groups. A series of 1,4,8,11,15,18,22,25-octaalkoxy metal-free and metal phthalocyanines and 2,3,9,10,16,17,23,24-octaalkoxy metal phthalocyanines has been synthesized. Their nonlinear optical properties have been measured. The physical properties of all the phthalocyanines synthesized in this work are subject to both acid and solvent effects.

  10. Miniature hybrid optical imaging lens

    DOEpatents

    Sitter, D.N. Jr.; Simpson, M.L.

    1997-10-21

    A miniature lens system that corrects for imaging and chromatic aberrations is disclosed, the lens system being fabricated from primarily commercially-available components. A first element at the input to a lens housing is an aperture stop. A second optical element is a refractive element with a diffractive element closely coupled to, or formed a part of, the rear surface of the refractive element. Spaced closely to the diffractive element is a baffle to limit the area of the image, and this is closely followed by a second refractive lens element to provide the final correction. The image, corrected for aberrations exits the last lens element to impinge upon a detector plane were is positioned any desired detector array. The diffractive element is fabricated according to an equation that includes, as variables, the design wavelength, the index of refraction and the radius from an optical axis of the lens system components. 2 figs.

  11. Miniature hybrid optical imaging lens

    DOEpatents

    Sitter, Jr., David N.; Simpson, Marc L.

    1997-01-01

    A miniature lens system that corrects for imaging and chromatic aberrations, the lens system being fabricated from primarily commercially-available components. A first element at the input to a lens housing is an aperture stop. A second optical element is a refractive element with a diffractive element closely coupled to, or formed a part of, the rear surface of the refractive element. Spaced closely to the diffractive element is a baffle to limit the area of the image, and this is closely followed by a second refractive lens element to provide the final correction. The image, corrected for aberrations exits the last lens element to impinge upon a detector plane were is positioned any desired detector array. The diffractive element is fabricated according to an equation that includes, as variables, the design wavelength, the index of refraction and the radius from an optical axis of the lens system components.

  12. Applied nonlinear optics in the journal 'Quantum Electronics'

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Chirkin, Anatolii S

    2011-12-31

    A brief historical review of the experimental and theoretical works on nonlinear optical frequency conversion (generation of harmonics, up- and down-conversion, parametric oscillation), which have been published in the journal 'Quantum Electronics' for the last 40 years, is presented.

  13. Diagrammatic evaluation of the density operator for nonlinear optical calculations

    NASA Technical Reports Server (NTRS)

    Yee, S. Y.; Gustafson, T. K.; Druet, S. A. J.; Taran, J.-P. E.

    1977-01-01

    Time-ordered diagrammatic representations are shown to precisely define and to simplify calculations of radiative perturbations to the density matrix. Nonlinear optical susceptibilities, here exemplified by that of CARS, can be obtained by simple propagator rules. An interpretation of transient Raman scattering in terms of time-ordered contributions is also discussed.

  14. Nonlinear optical properties of rigid-rod polymers

    NASA Technical Reports Server (NTRS)

    Trimmer, Mark S.; Wang, Ying

    1992-01-01

    The purpose of this research project was to integrate enhanced third order nonlinear optical (NLO) properties, especially high x(exp (3)) (greater than 10(exp -8) esu), into Maxdem's novel conjugated rigid-rod polymers while retaining their desirable processing, mechanical, and thermal properties. This work primarily involved synthetic approaches to optimized materials.

  15. Nonlinear interaction of meta-atoms through optical coupling

    SciTech Connect

    Slobozhanyuk, A. P.; Kapitanova, P. V.; Filonov, D. S.; Belov, P. A.; Powell, D. A.; Shadrivov, I. V.; Kivshar, Yu. S.; Lapine, M.; McPhedran, R. C.

    2014-01-06

    We propose and experimentally demonstrate a multi-frequency nonlinear coupling mechanism between split-ring resonators. We engineer the coupling between two microwave resonators through optical interaction, whilst suppressing the direct electromagnetic coupling. This allows for a power-dependent interaction between the otherwise independent resonators, opening interesting opportunities to address applications in signal processing, filtering, directional coupling, and electromagnetic compatibility.

  16. New - and Photoswitchable Chromophores for Second-Order Nonlinear Optics

    NASA Astrophysics Data System (ADS)

    Sanguinet, L.; Ahmed, S.; Pozzo, J. L.; Rodriguez, V.; Adamietz, F.

    New acidochromic and photochromic compounds with nonlinear optical properties have been designed and synthesized. The hyperpolarizabilities of the zwitterionic colored forms have been quantified with polarized hyper-Rayleigh scattering experiments. The static value of oxazolidino-indoline 2 is found to be as high as Disperse Red One. This opens the way to novel multi-addressable NLO-systems.

  17. Shape-Dependent Nonlinear Optical Properties of Anisotropic Gold Nanoparticles.

    PubMed

    Hua, Yi; Chandra, Kavita; Dam, Duncan Hieu M; Wiederrecht, Gary P; Odom, Teri W

    2015-12-17

    This Letter reports the shape-dependent third-order nonlinear optical properties of anisotropic gold nanoparticles. We characterized the nonlinear absorption coefficients of nanorods, nanostars, and nanoshells using femtosecond Z-scan measurements. By comparing nanoparticle solutions with a similar linear extinction at the laser excitation wavelength, we separated shape effects from that of the localized surface plasmon wavelength. We found that the nonlinear response depended on particle shape. Using pump-probe spectroscopy, we measured the ultrafast transient response of nanoparticles, which supported the strong saturable absorption observed in nanorods and weak nonlinear response in nanoshells. We found that the magnitude of saturable absorption as well as the ultrafast spectral responses of nanoparticles were affected by the linear absorption of the nanoparticles. PMID:26595327

  18. Multimodal nonlinear optical microscopy used to discriminate human colon cancer

    NASA Astrophysics Data System (ADS)

    Adur, Javier; Pelegati, Vitor B.; Bianchi, Mariana; de Thomaz, André A.; Baratti, Mariana O.; Carvalho, Hernandes F.; Casco, Víctor H.; Cesar, Carlos L.

    2013-02-01

    Colon cancer is one of the most diffused cancers in the Western World, ranking third worldwide in frequency of incidence after lung and breast cancers. Even if it is curable when detected and treated early, a more accurate premature diagnosis would be a suitable aim for both cancer prognostic and treatment. Combined multimodal nonlinear optical (NLO) microscopies, such as two-photon excitation fluorescence (TPEF), second-harmonic generation (SHG), third harmonic generation (THG), and fluorescence lifetime imaging microscopy (FLIM) can be used to detect morphological and metabolic changes associated with stroma and epithelial transformation in colon cancer disease. NLO microscopes provide complementary information about tissue microstructure, showing distinctive patterns between normal and malignant human colonic mucosa. Using a set of scoring methods significant differences both in the content, distribution and organization of stroma collagen fibrils, and lifetime components of NADH and FAD cofactors of human colon mucosa biopsies were found. Our results provide a framework for using NLO techniques as a clinical diagnostic tool for human colon cancer, and also suggest that the SHG and FLIM metrics could be applied to other intestinal disorders, which are characterized by abnormal cell proliferation and collagen assembly.

  19. Nonlinear optical coupler using a doped optical waveguide

    DOEpatents

    Pantell, Richard H.; Sadowski, Robert W.; Digonnet, Michel J. F.; Shaw, Herbert J.

    1994-01-01

    An optical mode coupling apparatus includes an Erbium-doped optical waveguide in which an optical signal at a signal wavelength propagates in a first spatial propagation mode and a second spatial propagation mode of the waveguide. The optical signal propagating in the waveguide has a beat length. The coupling apparatus includes a pump source of perturbational light signal at a perturbational wavelength that propagates in the waveguide in the first spatial propagation mode. The perturbational signal has a sufficient intensity distribution in the waveguide that it causes a perturbation of the effective refractive index of the first spatial propagation mode of the waveguide in accordance with the optical Kerr effect. The perturbation of the effective refractive index of the first spatial propagation mode of the optical waveguide causes a change in the differential phase delay in the optical signal propagating in the first and second spatial propagation modes. The change in the differential phase delay is detected as a change in the intensity distribution between two lobes of the optical intensity distribution pattern of an output signal. The perturbational light signal can be selectively enabled and disabled to selectively change the intensity distribution in the two lobes of the optical intensity distribution pattern.

  20. Adaptive optics for deeper imaging of biological samples.

    PubMed

    Girkin, John M; Poland, Simon; Wright, Amanda J

    2009-02-01

    Optical microscopy has been a cornerstone of life science investigations since its first practical application around 400 years ago with the goal being subcellular resolution, three-dimensional images, at depth, in living samples. Nonlinear microscopy brought this dream a step closer, but as one images more deeply the material through which you image can greatly distort the view. By using optical devices, originally developed for astronomy, whose optical properties can be changed in real time, active compensation for sample-induced aberrations is possible. Submicron resolution images are now routinely recorded from depths over 1mm into tissue. Such active optical elements can also be used to keep conventional microscopes, both confocal and widefield, in optimal alignment. PMID:19272766

  1. Preliminary investigation fo the non-linear response of image intensifiers used for gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Fastje, David; Barber, H. Bradford; Bora, Vaibhav; Lemieux, Daniel; Miller, Brian; Grim, Gary P.

    2013-09-01

    Image intensifiers combined with columnar scintillators have found application in x-ray and gamma-ray, biomedical imaging and other fields. In scintillator imaging, hundreds or thousands of optical photons can illuminate the faceplate of the image intensifier in a small area, essentially simultaneously. This is a situation not found in the typical design application for an image intensifier, night vision or low-light-level imaging. Microchannel plates (MCPs) are known to exhibit gain saturation that could result in non-linear signal response in scintillator imaging, limiting quantitative measurement capabilities. A calibrated LED photon source was developed that can provide a known average number of photons per unit area in a small spot size, similar to that seen due to a gamma-ray interaction in a BazookaSPECT imager. A BazookaSPECT imager is composed of a columnar scintillator and an image intensifier, with output light optically imaged onto a CCD camera. The calibrated source was used to investigate gain-saturation effects for two Proxivision, GmbH image intensifiers, a single-stage BV 2583 EZ and a two stage BV 2583 QZ-V 100N in a BazookaSPECT imaging configuration. No gain saturation was found for the single-stage image intensifier up to more than 100 optical photons per microchannel, but significant gain-saturation non-linearities were measured in the two-stage image intensifier at high gains for >12 optical photons per microchannel. Implications for scintillator imaging using such systems are discussed.

  2. Silicon Microdisk Resonators for Nonlinear Optics and Dynamics

    NASA Astrophysics Data System (ADS)

    Johnson, Thomas

    Silicon is incredibly well-studied as an electronic material. Since the out-migration of William Noyce, Gordon Moore, and the rest of the original Fairchild Semiconductor class from Shockley Semiconductor, silicon has only grown in prominence. Untold billions have been expended on research, development, and manufacture, and now silicon is perhaps the most well-controlled commercial material on Earth. For all that, the use of silicon as a mechanical material, though envisioned in the late 1950s, largely became viable only after the advent of large-scale silicon processing for microelectronics. As an optical material, silicon also has a long pedigree, with most of the positive focus on its excellent optical transparency and the enormous potential for improvement residing in its lack of effective emission. This thesis concerns an alternate route to the generation of light in silicon: the nonlinear route. Resonant elements play a critical role in making this viable. The ability to build up optical intensity in the confined volume of a microresonator reduces the input power required to achieve a given energy density. Silicon also has certain excellent nonlinear properties: a large Raman gain coefficient, for example, and an appreciable Kerr effect. Unfortunately, silicon also exhibits significant two-photon absorption (TPA) in the convenient telecommunications wavelength bands. As such, the build-up of optical energy in silion may also be accompanied by a build-up of TPA-induced free-carrier populations. These populations may serve to limit the efficiency of nonlinear processes or to generate additional nonlinear behavior in their interactions with optical fields. Thus two important stepping-stones on the way to the low-power, low-footprint use of silicon as an optical material are: the need to reduce optical losses in the optical elements, and to reduce or modify the populations of free carriers generated in the nonlinear optics regime. This thesis will present design

  3. 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.

  4. Nonlinear optical transmission of cyanobacteria-derived optical materials

    NASA Astrophysics Data System (ADS)

    Zhao, Edward H.; Watanabe, Fumiya; Zhao, Wei

    2015-08-01

    Cyanobacteria-derived optical materials for optical limiting applications have been studied in this work. Six samples have been prepared from cyanobacteria including cyanobacteria suspension in water, extracts in water, methanol, and N,N-dimethylformamide, and pyrolyzed cyanobacteria (PCYB) dispersed in dsDNA (sodium salt from salmon testes) solution and sodium dodecyl sulfate solution, respectively. The extracts contain phycocyanin, chlorophyll a, and carotenoids as measured by optical absorption spectroscopy, while the PCYB is a nanostructural composite composed of multi-walled carbon nanotubes, carbon nanoringes, and multilayer graphenes, as revealed by transmission electron microscopy. The optical limiting responses of the samples have been measured at 532 and 756 nm. The PCYB in dsDNA solution has the best limiting performance out of all the cyanobacteria-derived samples. It outperforms carbon black suspension standard at 532 nm and is a broadband limiter, which makes it attractive for optical limiting applications.

  5. Phase matching using an isotropic nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Fiore, A.; Berger, V.; Rosencher, E.; Bravetti, P.; Nagle, J.

    1998-01-01

    Frequency conversion in nonlinear optical crystals, is an effective means of generating coherent light at frequencies where lasers perform poorly or are unavailable. For efficient conversion, it is necessary to compensate for optical dispersion, which results in different phase velocities for light of different frequencies. In anisotropic birefringent crystals such as LiNbO3 or KH2PO4 (`KDP'), phase matching can be achieved between electromagnetic waves having different polarizations. But this is not possible for optically isotropic materials, and as a result, cubic materials such as GaAs (which otherwise have attractive nonlinear optical properties) have been little exploited for frequency conversion applications. Quasi-phase-matching schemes,, which have achieved considerable success in LiNbO3 (ref. 4), provide a route to circumventing this problem,, but the difficulty of producing the required pattern of nonlinear properties in isotropic materials, particularly semiconductors, has limited the practical utility of such approaches. Here we demonstrate a different route to phase matching - based on a concept proposed by Van der Ziel 22 years ago - which exploits the artificial birefringence of multilayer composites of GaAs and oxidised AlAs. As GaAs is the material of choice for semiconductor lasers, such optical sources could be integrated in the core of frequency converters based on these composite structures.

  6. Nonlinear Optics and Solitons in Photonic Crystal Fibres

    NASA Astrophysics Data System (ADS)

    Skryabin, Dmitry V.; Wadsworth, William J.

    The fibre optics revolution in communication technologies followed the 1950's demonstration of the glass fibres with dielectric cladding [1]. Transmission applications of fibre optics have become a dominant modern day technology not least because nonlinearities present in - or introduced into - glass and enhanced by the tight focusing of the fibre modes allow for numerous light processing techniques, such as amplification, frequency conversion, pulse shaping, and many others. For these reasons, and because of the rich fundamental physics behind it, nonlinear fibre optics has become a blossoming discipline in its own right [1]. The 1990's witnessed another important development in fibre optics. Once again it came from a new approach to the fibre cladding, comprising a periodic pattern of air holes separated by glass membranes forming a photonic crystal structure [2, 3]. This prompted the name Photonic Crystal Fibres (PCFs). The fascinating story behind the invention of PCF and research into various fibre designs can be found, e.g., in [4]. Our aim here is to review the role played by PCFs in nonlinear and quantum optics, which is becoming the mainstream of the PCF related research and applications. Our focus will be on the areas where PCFs have brought to life effects and applications which were previously difficult, impossible to observe or simply not thought about.

  7. Nonlinear optical response of metal-barrier-metal junctions

    NASA Technical Reports Server (NTRS)

    Fan, B.; Faris, S. M.; Gustafson, T. K.; Bridges, T. J.

    1977-01-01

    The optical response of metal-barrier-metal (MBM) junctions is discussed, with emphasis on the nonlinearity of response associated with reversal of polarity as optical intensity is increased. This nonlinear behavior can be used to measure correlation functions of optical pulses or to generate ultrashort electrical pulses. Expressions for the current flowing through the insulating barrier (junction), and for the rectification current, are given. Pulse signal and polarity of the electrical pulse evolves as the junction bias is varied about the null-signal bias. The apparatus used to obtain rectification pulse signals is described; the calculated evolution of the rectified pulse shape is found to correspond to that of pulse signals obtained experimentally. The generation of pulses six orders of magnitude smaller than a previously-obtained instrument-limited 1.6 nanosecond pulse has been observed.

  8. New multiband IR imaging optics

    NASA Astrophysics Data System (ADS)

    Bayya, Shyam; Sanghera, Jasbinder; Kim, Woohong; Gibson, Daniel; Fleet, Erin; Shaw, Brandon; Hunt, Michael; Aggarwal, Ishwar

    2013-06-01

    We report new multispectral materials that transmit from 0.9 to < 12 µm in wavelength. These materials fill up the glass map for multispectral optics and vary in refractive index from 2.38 to 3.17. They show a large spread in dispersion (Abbe number) and offer some unique solutions for multispectral optics designs. One of the glasses developed is a very good candidate to replace Ge, as it has a combination of excellent properties, including high Abbe number in the LWIR, high index of 3.2, 60% lower dn/dT, and better thermal stability at working temperatures. Our results also provide a wider selection of optical materials to enable simpler achromat designs. For example, we have developed other glasses that have relatively high Abbe number in both the MWIR and LWIR regions, while our MILTRAN ceramic has low Abbe number in both regions. This makes for a very good combination of glasses and MILTRAN ceramic (analogous to crown and flint glasses in the visible) for MWIR + LWIR dual band imaging. We have designed preliminary optics for one such imager with f/2.5, 51 mm focal length and 22 degrees FOV using a spaced doublet of NRL's glass and MILTRAN ceramic. NRL's approach reduces the number of elements, weight, complexity and cost compared with the approach using traditional optics. Another important advantage of using NRL glasses in optics design is their negative or very low positive dn/dT, that makes it easier to athermalize the optical system.

  9. In-vivo monitoring rat skin wound healing using nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Guo, Chungen; Zhang, Fan; Xu, Yahao; Zhu, Xiaoqin; Xiong, Shuyuan; Chen, Jianxin

    2014-11-01

    Nonlinear optical microscopy (NLOM) was employed for imaging and evaluating the wound healing process on rat skin in vivo. From the high-resolution nonlinear optical images, the morphology and distribution of specific biological markers in cutaneous wound healing such as fibrin clot, collagens, blood capillaries, and hairs were clearly observed at 1, 5 and 14 days post injury. We found that the disordered collagen in the fibrin clot at day 1 was replaced by regenerative collagen at day 5. By day 14, the thick collagen with well-network appeared at the original margin of the wound. These findings suggested that NLOM is ideal for noninvasively monitoring the progress of wound healing in vivo.

  10. Optical molecular imaging in PDT

    NASA Astrophysics Data System (ADS)

    Mitra, Soumya; Snyder, John W.; Foster, Thomas H.

    2007-02-01

    Motivated by recent successes in fluorescence imaging of whole mount tissue preparations and by rapid progress in the fields of molecular imaging and molecular biology, we are exploring a number of applications of optical fluorescence imaging in superficial murine tumor models in vivo. Imaging the PDT-induced expression of the heat shock protein 70 (HSP70) in cells and in vivo is accomplished using stably transfected EMT6 cells in which the gene for GFP is under the control of the HSP70 promoter. These cells readily form solid tumors in BALB/c mice, enabling the direct imaging of the extent and time course of the activation of this promoter, with each mouse serving as its own control. Imaging of similarly transfected EMT6 cells with a HIF-1α/GFP fusion protein vector enables visualization of HIF-1α translocation to the nucleus. Recently, we have accomplished fluorescent labeling of surface antigens in vivo using intratumor and intravenous injection of fluorophore-conjugated antibodies. Injection of deep-red fluorophore-conjugated-anti-CD31 enables confocal fluorescence imaging of the tumor vasculature to depths of at least 100 microns. With the vessels rendered fluorescent in this way, a number of interesting studies become possible in the living mouse, including the direct visualization of photosensitizer distribution from perfused vessels. Using the appropriate fluorophore-conjugated antibodies, we have also been able to image infiltrating granulocytes in EMT6 tumors in response to PDT in vivo.

  11. REVIEW ARTICLE: Slow light enhanced nonlinear optics in periodic structures

    NASA Astrophysics Data System (ADS)

    Monat, C.; de Sterke, M.; Eggleton, B. J.

    2010-10-01

    We review recent advances related to slow light in periodic structures, where the refractive index varies along one or two directions, i.e. gratings and planar photonic crystals. We focus on how these geometries are conducive to enhancing the nonlinear interaction between light and matter. We describe the underlying theory developed for shallow gratings, but whose conclusions can be extended to planar photonic crystal waveguides, in particular the enhancement of third-order nonlinear processes with slow light. We review some experiments showing how gratings have been used for pulse compression and the generation of slow gap solitons. We then present recent nonlinear experiments performed in photonic crystal waveguides that demonstrate the strong reinforcement of nonlinear third-order optical phenomena with slow light. We discuss the challenges associated with slow light in these 2D structures and their unique advantage—dispersion engineering—for creating broadband nonlinear devices for all-optical signal processing. By breaking down the relation between dispersion and group velocity imposed in gratings, these structures also offer new opportunities for generating soliton-like effects over short length scales, at low powers and with short pulses.

  12. Nonlinear optical properties of multilayer graphene in the infrared.

    PubMed

    Demetriou, Giorgos; Bookey, Henry T; Biancalana, Fabio; Abraham, Eitan; Wang, Yu; Ji, Wei; Kar, Ajoy K

    2016-06-13

    A negative value for the nonlinear refraction in graphene is experimentally observed and unambiguously verified by performing a theoretical analysis arising from the conductivity of the graphene monolayer. The nonlinear optical properties of multi-layer graphene are experimentally studied by employing the Z-scan technique. The measurements are carried out at 1150, 1550, 1900 and 2400 nm with a 100-femtosecond laser source. Under laser illumination the multi-layer graphene exhibits a transmittance increase due to saturable absorption, followed by optical limiting due to two-photon absorption. The saturation irradiance Isat and the two-photon absorption coefficient β are measured in the operating wavelength range. Furthermore, an irradiance-dependent nonlinear refraction is observed and discriminated from the conventional nonlinear refraction coefficient n2, which is not irradiance dependent. The values obtained for the irradiance-dependent nonlinear refraction are in the order of ∼10-9 cm2W-1, approximately 8 orders of magnitude larger than any bulk dielectrics. PMID:27410322

  13. Second-order nonlinear optical metamaterials: ABC-type nanolaminates

    SciTech Connect

    Alloatti, L. Kieninger, C.; Lauermann, M.; Köhnle, K.; Froelich, A.; Wegener, M.; Frenzel, T.; Freude, W.; Leuthold, J.; Koos, C.

    2015-09-21

    We demonstrate a concept for second-order nonlinear metamaterials that can be obtained from non-metallic centrosymmetric constituents with inherently low optical absorption. The concept is based on iterative atomic-layer deposition of three different materials, A = Al{sub 2}O{sub 3}, B = TiO{sub 2}, and C = HfO{sub 2}. The centrosymmetry of the resulting ABC stack is broken since the ABC and the inverted CBA sequences are not equivalent—a necessary condition for non-zero second-order nonlinearity. In our experiments, we find that the bulk second-order nonlinear susceptibility depends on the density of interfaces, leading to a nonlinear susceptibility of 0.26 pm/V at a wavelength of 800 nm. ABC-type nanolaminates can be deposited on virtually any substrate and offer a promising route towards engineering of second-order optical nonlinearities at both infrared and visible wavelengths.

  14. Infrared upconversion as a means of seeing in the dark. [based on nonlinear crystal optics

    NASA Technical Reports Server (NTRS)

    Gurski, T. R.

    1975-01-01

    A new approach to seeing in the dark is described which is based on the principles of nonlinear optics employing a crystal such as lithium iodate. A nonlinear optical device capable of producing photons at higher frequencies from lower-frequency incident light is shown to upconvert infrared light directly into visible light. The major advantages of the infrared upconversion process is that it permits the infrared signal to be detected by photon-counting devices presently available for the visible spectral region, and that it can provide sensitivity to infrared radiation without the need for cryogenic cooling of the detector used. Early works on infrared upconversion are reviewed. The development of applications is discussed as to astronomical spectroscopy and infrared image upconversion involving either angular or positional resolution elements. The demonstration of infrared upconversion in rectangular waveguides of single-crystal GaAs by Anderson et al. (1971) indicates future possibilities in upconversion by the use of integrated optics devices.

  15. Heterointerface effects on the nonlinear optical rectification in a laser-dressed graded quantum well

    NASA Astrophysics Data System (ADS)

    Niculescu, Ecaterina C.; Eseanu, Nicoleta; Radu, Adrian

    2013-05-01

    An investigation of the laser radiation effects on the nonlinear optical rectification in an AlGaAs inverse parabolic quantum well with asymmetrical barriers is performed within the effective mass approximation, taking into account the dielectric mismatch between the semiconductor and the surrounding medium. Using the accurate dressing effect for the confinement potential and electrostatic self-energy due to the image-charges, we prove that: (i) a spatially dependent effective mass in the laser-dressing parameter definition is required for precise calculations of the energy levels; (ii) the dielectric confinement provides a potential mechanism for controlling electronic states and optical properties of quantum wells. In addition, the laser dependence of the energy where the optical rectification reaches its maximum can be adjusted by external electric fields. The joint action of the intense high-frequency laser and static electric fields may provide tuning of the nonlinear properties in this type of dielectrically modulated heterostructures.

  16. The extreme nonlinear optics of gases and femtosecond optical filamentation

    SciTech Connect

    Milchberg, H. M.; Chen, Y.-H.; Cheng, Y.-H.; Jhajj, N.; Palastro, J. P.; Rosenthal, E. W.; Varma, S.; Wahlstrand, J. K.; Zahedpour, S.

    2014-10-15

    Under certain conditions, powerful ultrashort laser pulses can form greatly extended, propagating filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction, with possible applications ranging from laser-guided electrical discharges to high power laser propagation in the atmosphere. Understanding in detail the microscopic processes leading to filamentation requires ultrafast measurements of the strong field nonlinear response of gas phase atoms and molecules, including absolute measurements of nonlinear laser-induced polarization and high field ionization. Such measurements enable the assessment of filamentation models and make possible the design of experiments pursuing applications. In this paper, we review filamentation in gases and some applications, and discuss results from diagnostics developed at Maryland for ultrafast measurements of laser-gas interactions.

  17. In situ 3D characterization of historical coatings and wood using multimodal nonlinear optical microscopy.

    PubMed

    Latour, Gaël; Echard, Jean-Philippe; Didier, Marie; Schanne-Klein, Marie-Claire

    2012-10-22

    We demonstrate multimodal nonlinear optical imaging of historical artifacts by combining Second Harmonic Generation (SHG) and Two-Photon Excited Fluorescence (2PEF) microscopies. We first identify the nonlinear optical response of materials commonly encountered in coatings of cultural heritage artifacts by analyzing one- and multi-layered model samples. We observe 2PEF signals from cochineal lake and sandarac and show that pigments and varnish films can be discriminated by exploiting their different emission spectral ranges as in luminescence linear spectroscopy. We then demonstrate SHG imaging of a filler, plaster, composed of bassanite particles which exhibit a non centrosymmetric crystal structure. We also show that SHG/2PEF imaging enables the visualization of wood microstructure through typically 60 µm-thick coatings by revealing crystalline cellulose (SHG signal) and lignin (2PEF signal) in the wood cell walls. Finally, in situ multimodal nonlinear imaging is demonstrated in a historical violin. SHG/2PEF imaging thus appears as a promising non-destructive and contactless tool for in situ 3D investigation of historical coatings and more generally for wood characterization and coating analysis at micrometer scale. PMID:23187225

  18. Thermally induced optical nonlinearity during transient heating of thin films

    SciTech Connect

    Chen, G. ); Tien, C.L. )

    1994-05-01

    This work studies the temperature field and the optical response of weakly absorbing thin films with thermally induced optical nonlinearity during picosecond to nanosecond pulsed-laser heating. A one-dimensional model is presented that examines the effects of the temperature dependent optical constants and the nonuniform absorption caused by interference. The energy equation is solved numerically, coupled with the matrix method in optical multilayer theory. Both cadmium sulfide (CdS) thin films and a zinc selenide (ZnSe) interference filter are considered. The computational results compare favorably with available experimental data on the ZnSe interference filter. This study shows that the transient temperature distributions in the films are highly nonuniform. Such nonuniformity yields Airy's formulae for calculating the thin-film reflectance and transmittance inapplicable. Applications of the work include optical bistability, localized change of the film structure, and measurement of the thermal diffusivity of thin films. 31 refs., 7 figs., 1 tab.

  19. Third order nonlinear optical response exhibited by mono- and few-layers of WS2

    NASA Astrophysics Data System (ADS)

    Torres-Torres, Carlos; Perea-López, Néstor; Elías, Ana Laura; Gutiérrez, Humberto R.; Cullen, David A.; Berkdemir, Ayse; López-Urías, Florentino; Terrones, Humberto; Terrones, Mauricio

    2016-06-01

    In this work, strong third order nonlinear optical properties exhibited by WS2 layers are presented. Optical Kerr effect was identified as the dominant physical mechanism responsible for these third order optical nonlinearities. An extraordinary nonlinear refractive index together with an important contribution of a saturated absorptive response was observed to depend on the atomic layer stacking. Comparative experiments performed in mono- and few-layer samples of WS2 revealed that this material is potentially capable of modulating nonlinear optical processes by selective near resonant induced birefringence. We envision applications for developing all-optical bidimensional nonlinear optical devices.

  20. Self-characterization of linear and nonlinear adaptive optics systems.

    PubMed

    Hampton, Peter J; Conan, Rodolphe; Keskin, Onur; Bradley, Colin; Agathoklis, Pan

    2008-01-10

    We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM. PMID:18188192

  1. Self-similarity and optical kinks in resonant nonlinear media

    SciTech Connect

    Ponomarenko, Sergey A.; Haghgoo, Soodeh

    2010-11-15

    We show that self-similar optical waves with a kink structure exist in a wide class of resonant nonlinear media, adequately treated in the two-level approximation. The self-similar structure of the present kinks is reflected in the time evolution of the field profile, atomic dipole moment, and one-atom inversion. We develop an analytical theory of such kinks. We show that the discovered kinks are accelerating nonlinear waves, asymptotically attaining their shape and the speed of light. We also numerically explore the formation and eventual disintegration of our kinks due to energy relaxation processes. Thus, the present kinks can be viewed as intermediate asymptotics of the system.

  2. Reversible Photoswitching of the Interfacial Nonlinear Optical Response.

    PubMed

    Schulze, Michael; Utecht, Manuel; Hebert, Andreas; Rück-Braun, Karola; Saalfrank, Peter; Tegeder, Petra

    2015-02-01

    Incorporating photochromic molecules into organic/inorganic hybrid materials may lead to photoresponsive systems. In such systems, the second-order nonlinear properties can be controlled via external stimulation with light at an appropriate wavelength. By creating photochromic molecular switches containing self-assembled monolayers on Si(111), we can demonstrate efficient reversible switching, which is accompanied by a pronounced modulation of the nonlinear optical (NLO) response of the system. The concept of utilizing functionalized photoswitchable Si surfaces could be a way for the generation of two-dimensional NLO switching materials, which are promising for applications in photonic and optoelectronic devices. PMID:26261971

  3. All-optical processing in coherent nonlinear spectroscopy

    SciTech Connect

    Oron, Dan; Dudovich, Nirit; Silberberg, Yaron

    2004-08-01

    In spectroscopy, the fingerprint of a substance is usually comprised of a sequence of spectral lines with characteristic frequencies and strengths. Identification of substances often involves postprocessing, where the measured spectrum is compared with tabulated fingerprint spectra. Here we suggest a scheme for nonlinear spectroscopy, where, through coherent control of the nonlinear process, the information from the entire spectrum can be practically collected into a single coherent entity. We apply this for all-optical analysis of coherent Raman spectra and demonstrate enhanced detection and effective background suppression using coherent processing.

  4. Nonlinear optical responses of erbium-doped YAG ceramics

    NASA Astrophysics Data System (ADS)

    Sun, Wangliang; Yi, Jun; Miao, Lili; Li, Jiang; Xie, Tengfei; Zhao, Chujun; Pan, Yubai; Wen, Shuangchun

    2016-07-01

    By performing the Z-scan measurements with ultrafast femtosecond laser centered at 800 nm wavelength, we can unambiguously distinguish the real and imaginary part of the third-order optical nonlinearity of the erbium-doped YAG ceramics. The reverse saturable absorption of the erbium-doped YAG ceramics has been observed experimentally, and the nonlinear refractive index of the ceramics is estimated to be about 10-21 m2/W. The experimental results may provide design guidelines for the high power laser design and its applications.

  5. Fluorescence imaging spectrometer optical design

    NASA Astrophysics Data System (ADS)

    Taiti, A.; Coppo, P.; Battistelli, E.

    2015-09-01

    The optical design of the FLuORescence Imaging Spectrometer (FLORIS) studied for the Fluorescence Explorer (FLEX) mission is discussed. FLEX is a candidate for the ESA's 8th Earth Explorer opportunity mission. FLORIS is a pushbroom hyperspectral imager foreseen to be embarked on board of a medium size satellite, flying in tandem with Sentinel-3 in a Sun synchronous orbit at a height of about 815 km. FLORIS will observe the vegetation fluorescence and reflectance within a spectral range between 500 and 780 nm. Multi-frames acquisitions on matrix detectors during the satellite movement will allow the production of 2D Earth scene images in two different spectral channels, called HR and LR with spectral resolution of 0.3 and 2 nm respectively. A common fore optics is foreseen to enhance by design the spatial co-registration between the two spectral channels, which have the same ground spatial sampling (300 m) and swath (150 km). An overlapped spectral range between the two channels is also introduced to simplify the spectral coregistration. A compact opto-mechanical solution with all spherical and plane optical elements is proposed, and the most significant design rationales are described. The instrument optical architecture foresees a dual Babinet scrambler, a dioptric telescope and two grating spectrometers (HR and LR), each consisting of a modified Offner configuration. The developed design is robust, stable vs temperature, easy to align, showing very high optical quality along the whole field of view. The system gives also excellent correction for transverse chromatic aberration and distortions (keystone and smile).

  6. Simple nonlinear interferometer-based all-optical thresholder and its applications for optical CDMA.

    PubMed

    Kravtsov, Konstantin; Prucnal, Paul R; Bubnov, Mikhail M

    2007-10-01

    We present an experimental demonstration of an ultrafast all-optical thresholder based on a nonlinear Sagnac interferometer. The proposed design is intended for operation at very small nonlinear phase shifts. Therefore, it requires an in-loop nonlinearity lower than for the classical nonlinear loop mirror scheme. Only 15 meters of conventional (non-holey) silica-based fiber is used as a nonlinear element. The proposed thresholder is polarization insensitive and is good for multi-wavelength operation, meeting all the requirements for autocorrelation detection in various optical CDMA communication systems. The observed cubic transfer function is superior to the quadratic transfer function of second harmonic generation-based thresholders. PMID:19550579

  7. Spin and diamagnetism in linear and nonlinear optics

    SciTech Connect

    Andersen, Torsten; Keller, Ole; Huebner, Wolfgang; Johansson, Boerje

    2004-10-01

    We present a local-field theory for spin and diamagnetism in linear and nonlinear optics. We examine all the processes contained in the Pauli Hamiltonian and its corresponding microscopic current density, including the terms depending on the electron spin. The resulting general real-space conductivities are presented and discussed. To quantify the implications of including the spin, we study the linear and nonlinear optical properties of free-electron metals, represented by the screened homogeneous electron gas. The real-space formalism is transformed into Fourier space, and the symmetries of the linear and nonlinear optical conductivities in a homogeneous electron gas are discussed. Numerical results are presented for the homogeneous electron gas, in which we treat {omega} and q as independent variables, thereby opening the theory to near-field optics and the study of evanescent waves. We show that in regions of the {omega}-q spectrum, the presence of diamagnetism and spin dynamics significantly alters the response in comparison to considering only the paramagnetic response. Additionally, we discuss the effects of screening, and we finish our treatment by a discussion of how to connect the present theory to existing methods in ab initio solid-state physics.

  8. Optical Navigation Image of Ganymede

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA's Galileo spacecraft, now in orbit around Jupiter, returned this optical navigation image June 3, 1996, showing that the spacecraft is accurately targeted for its first flyby of the giant moon Ganymede on June 27. The missing data in the frame is the result of a special editing feature recently added to the spacecraft's computer to transmit navigation images more quickly. This is first in a series of optical navigation frames, highly edited onboard the spacecraft, that will be used to fine-tune the spacecraft's trajectory as Galileo approaches Ganymede. The image, used for navigation purposes only, is the product of new computer processing capabilities on the spacecraft that allow Galileo to send back only the information required to show the spacecraft is properly targeted and that Ganymede is where navigators calculate it to be. 'This navigation image is totally different from the pictures we'll be taking for scientific study of Ganymede when we get close to it later this month,' said Galileo Project Scientist Dr. Torrence Johnson. On June 27, Galileo will fly just 844 kilometers (524 miles) above Ganymede and return the most detailed, full-frame, high-resolution images and other measurements of the satellite ever obtained. Icy Ganymede is the largest moon in the solar system and three-quarters the size of Mars. It is one of the four large Jovian moons that are special targets of study for the Galileo mission. Of the more than 5 million bits contained in a single image, Galileo performed on-board editing to send back a mere 24,000 bits containing the essential information needed to assure proper targeting. Only the light-to-dark transitions of the crescent Ganymede and reference star locations were transmitted to Earth. The navigation image was taken from a distance of 9.8 million kilometers (6.1 million miles). On June 27th, the spacecraft will be 10,000 times closer to Ganymede.

  9. Viscous optical clearing agent for in vivo optical imaging

    NASA Astrophysics Data System (ADS)

    Deng, Zijian; Jing, Lijia; Wu, Ning; lv, Pengyu; Jiang, Xiaoyun; Ren, Qiushi; Li, Changhui

    2014-07-01

    By allowing more photons to reach deeper tissue, the optical clearing agent (OCA) has gained increasing attention in various optical imaging modalities. However, commonly used OCAs have high fluidity, limiting their applications in in vivo studies with oblique, uneven, or moving surfaces. In this work, we reported an OCA with high viscosity. We measured the properties of this viscous OCA, and tested its successful performances in the imaging of a living animal's skin with two optical imaging modalities: photoacoustic microscopy and optical coherence tomography. Our results demonstrated that the viscous OCA has a great potential in the study of different turbid tissues using various optical imaging modalities.

  10. Nonlinear-microscopy optical-pulse sources based on mode-locked semiconductor lasers.

    PubMed

    Yokoyama, H; Sato, A; Guo, H-C; Sato, K; Mure, M; Tsubokawa, H

    2008-10-27

    We developed picosecond optical-pulse sources suitable for multiphoton microscopy based on mode-locked semiconductor lasers. Using external-cavity geometry, stable hybrid mode locking was achieved at a repetition rate of 500 MHz. Semiconductor optical amplifiers driven by synchronized electric pulses reached subharmonic optical-pulse repetition rates of 1-100 MHz. Two-stage Yb-doped fiber amplifiers produced optical pulses of 2 ps duration, with a peak power of a few kilowatts at a repetition rate of 10 MHz. These were employed successfully for nonlinear-optic bio-imaging using two-photon fluorescence, second-harmonic generation, and sum-frequency generation of synchronized two-color pulses. PMID:18958056

  11. Nonlinear optical properties of bismuth selenide

    NASA Astrophysics Data System (ADS)

    Bas, Derek; Babakiray, Sercan; Stanescu, Tudor; Lederman, David; Bristow, Alan

    Bismuth selenide (Bi2Se3) is a topological insulator with many interesting photonic properties. Much research has been done involving various types of photocurrents in an attempt to highlight the differences between the bulk electronic states and massless conducting surface states. Here, Bi2Se3 films varying in thickness from 6 to 40 quintuple layers have been produced via molecular beam epitaxy as a means to vary the relative contributions of bulk and surface. On these samples, optical measurements were performed at around 1.6 eV, which is enough energy to stimulate transitions from the Fermi level to a region near the second Dirac cone. Z-scan was used to measure saturable absorption, time-resolved two-color pump-probe was used to measure two-photon absorption, and a Fourier transform infrared spectrometer was used to measure linear absorption. Results were examined and analyzed with respect to thickness. Thickness-dependent band structures were produced using a tight-binding model and used to compare with experimental results.

  12. Tunable optics derived from nonlinear acoustic effects

    NASA Astrophysics Data System (ADS)

    Higginson, Keith A.; Costolo, Michael A.; Rietman, Edward A.; Ritter, Joseph M.; Lipkens, Bart

    2004-05-01

    Gradient index lenses were formed in a liquid-filled cavity supporting an ultrasonic standing wave. The constructed devices acted as diverging lenses or axicon lenses, depending on whether the center or edge region is interrogated. The focal length of the diverging lens was controllable with the frequency and amplitude of applied ultrasound from -100 mm to negative infinity. Experiments and models suggest that the primary process contributing to lensing is the steady-state density component of the finite-amplitude standing wave; sound amplitudes up to 150 MPa were calculated in glycerin, corresponding to a maximum contrast in the refractive on the order of 0.1%. This amplitude was also sufficient to move high index nanometer-scale particles via an acoustic radiation force and thereby create larger refractive index gradients. The segregation of suspended nanoparticles was found to enhance the lensing effects that occurred in the pure fluids. Concepts are also explored to manipulate the particle distribution in order to create converging lenses and/or other desirable optical components.

  13. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    PubMed Central

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  14. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    PubMed

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  15. Numerical modelling and image reconstruction in diffuse optical tomography

    PubMed Central

    Dehghani, Hamid; Srinivasan, Subhadra; Pogue, Brian W.; Gibson, Adam

    2009-01-01

    The development of diffuse optical tomography as a functional imaging modality has relied largely on the use of model-based image reconstruction. The recovery of optical parameters from boundary measurements of light propagation within tissue is inherently a difficult one, because the problem is nonlinear, ill-posed and ill-conditioned. Additionally, although the measured near-infrared signals of light transmission through tissue provide high imaging contrast, the reconstructed images suffer from poor spatial resolution due to the diffuse propagation of light in biological tissue. The application of model-based image reconstruction is reviewed in this paper, together with a numerical modelling approach to light propagation in tissue as well as generalized image reconstruction using boundary data. A comprehensive review and details of the basis for using spatial and structural prior information are also discussed, whereby the use of spectral and dual-modality systems can improve contrast and spatial resolution. PMID:19581256

  16. Complex geometrical optics of Kerr type nonlinear media

    NASA Astrophysics Data System (ADS)

    Berczynski, P.; Kravtsov, Yu. A.; Sukhorukov, A. P.

    2010-03-01

    The paper generalizes paraxial complex geometrical optics (PCGO) for Gaussian beam (GB) propagation in nonlinear media of Kerr type. Ordinary differential equations for the beam amplitude and for complex curvature of the wave front are derived, which describe the evolution of axially symmetric GB in a Kerr type nonlinear medium. It is shown that PCGO readily provides the solutions of NLS equation obtained earlier from diffraction theory on the basis of the aberration-free approach. Besides reproducing classical results of self-focusing PCGO readily describes an influence of the initial curvature of the wave front on the beam evolution in a medium of Kerr type including a nonlinear graded-index fiber. The range of applicability of the PCGO theory is discussed as well which is helpful for avoiding nonphysical solutions.

  17. From Ewald sphere to Ewald shell in nonlinear optics.

    PubMed

    Huang, Huang; Huang, Cheng-Ping; Zhang, Chao; Hong, Xu-Hao; Zhang, Xue-Jin; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-01-01

    Ewald sphere is a simple vector scheme to depict the X-ray Bragg diffraction in a crystal. A similar method, known as the nonlinear Ewald sphere, was employed to illustrate optical frequency conversion processes. We extend the nonlinear Ewald sphere to the Ewald shell construction. With the Ewald shell, a variety of quasi-phase-matching (QPM) effects, such as the collective envelope effect associated with multiple QPM resonances, the enhanced second- harmonic generation due to multiple reciprocal vectors etc., are suggested theoretically and verified experimentally. By rotating the nonlinear photonic crystal sample, the dynamic evolution of these QPM effects has also been observed, which agreed well with the Ewald shell model. PMID:27386951

  18. Modulational instability in nonlinearity-managed optical media

    NASA Astrophysics Data System (ADS)

    Centurion, Martin; Porter, Mason A.; Pu, Ye; Kevrekidis, P. G.; Frantzeskakis, D. J.; Psaltis, Demetri

    2007-06-01

    We investigate analytically, numerically, and experimentally the modulational instability in a layered, cubically nonlinear (Kerr) optical medium that consists of alternating layers of glass and air. We model this setting using a nonlinear Schrödinger (NLS) equation with a piecewise constant nonlinearity coefficient and conduct a theoretical analysis of its linear stability, obtaining a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between the theoretical analysis of the Kronig-Penney equation, numerical simulations of the NLS equation, and the experimental results for the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, we find multiple instability regions rather than just the one that would occur in uniform media.

  19. From Ewald sphere to Ewald shell in nonlinear optics

    PubMed Central

    Huang, Huang; Huang, Cheng-Ping; Zhang, Chao; Hong, Xu-Hao; Zhang, Xue-Jin; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-01-01

    Ewald sphere is a simple vector scheme to depict the X-ray Bragg diffraction in a crystal. A similar method, known as the nonlinear Ewald sphere, was employed to illustrate optical frequency conversion processes. We extend the nonlinear Ewald sphere to the Ewald shell construction. With the Ewald shell, a variety of quasi-phase-matching (QPM) effects, such as the collective envelope effect associated with multiple QPM resonances, the enhanced second- harmonic generation due to multiple reciprocal vectors etc., are suggested theoretically and verified experimentally. By rotating the nonlinear photonic crystal sample, the dynamic evolution of these QPM effects has also been observed, which agreed well with the Ewald shell model. PMID:27386951

  20. Modulational instability in nonlinearity-managed optical media

    SciTech Connect

    Centurion, Martin; Porter, Mason A.; Pu Ye; Psaltis, Demetri; Kevrekidis, P. G.; Frantzeskakis, D. J.

    2007-06-15

    We investigate analytically, numerically, and experimentally the modulational instability in a layered, cubically nonlinear (Kerr) optical medium that consists of alternating layers of glass and air. We model this setting using a nonlinear Schroedinger (NLS) equation with a piecewise constant nonlinearity coefficient and conduct a theoretical analysis of its linear stability, obtaining a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between the theoretical analysis of the Kronig-Penney equation, numerical simulations of the NLS equation, and the experimental results for the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, we find multiple instability regions rather than just the one that would occur in uniform media.

  1. Nonlinear optical and optical limiting properties of graphene oxide dispersion in femtosecond regime

    NASA Astrophysics Data System (ADS)

    Zheng, Zebo; Zhu, Liang; Zhao, Fuli

    2014-08-01

    The third-order nonlinear optical properties of graphene oxide (GO) dispersion in distilled water were investigated in femtosecond regime, using a single beam z-scan technique. Induced by a focused Gaussian beam (λ~800 nm) with 150 fs pulse duration, the graphene oxide shows strong nonlinear absorption, which was dominated by reverse saturable absorption (RSA), originates from two-photon absorption (TPA) in GO. In addition, the optical limiting performance of GO was experimentally derived, indicating that the occurrence of RSA make GO a candidate for optical limiting. In addition, the further increasing of input intensity would enhance the nonlinear scattering effects in the sample so that the optical limiting threshold was reached.

  2. Nonlinear optical properties and optical limiting measurements of graphene oxide - Ag@TiO2 compounds

    NASA Astrophysics Data System (ADS)

    Ebrahimi, M.; Zakery, A.; Karimipour, M.; Molaei, M.

    2016-07-01

    In this work Graphene Oxide (GO), Ag@TiO2 core-shells and GO-Ag@TiO2 compounds were prepared and experimentally verified. Using a low power laser diode with 532 nm wavelength, the magnitude and the sign of the nonlinear refractive index and nonlinear absorption were determined by the Z-scan technique. It was observed that the nonlinear absorption of GO-Ag@TiO2 mixture was higher than pure GO. The optical limiting effect of these samples was also investigated using the 2nd harmonics of a pulsed Nd-YAG laser at 532 nm. Our results showed that the sole Ag@TiO2 didn't show any appreciable optical limiting effect, however after just mixing with graphene oxide the threshold of optical limiting was increased and the compound showed an enhancement of optical limiting behavior compared to GO itself. The presented results are discussed and compared with other literature reports.

  3. Optical imaging of biological tissues

    NASA Astrophysics Data System (ADS)

    Bouza Dominguez, Jorge

    In this thesis, a new time-dependent model for describing light propagation in biological media is proposed. The model is based on the simplified spherical harmonics approximation and is represented by a set of coupled parabolic partial differential equations (TD-pSPN equations). In addition, the model is extended for modeling the time-dependent response of fluorescent agents in biological tissues and the ensuing time-domain propagation of light therein. In a comparison with Monte Carlo simulations, it is shown that the TD-pSPN equations present unique features in its derivation that makes it a more accurate alternative to the diffusion equation (DE). The TD-pSPN model (for orders N > 1) outperforms the DE in the description of the propagation of light in near-nondiffusive media and in all the physical situations where DE fails. Often, only small orders of the SP N approximation are needed to obtain accurate results. A diffuse optical tomography (DOT) algorithm is also implemented based on the TD-pSPN equations as the forward model using constrained optimization methods. The algorithm uses time-dependent (TD) data directly. Such an approach is benefited from both the accuracy of the SPN models and the richness of TD data. In the calculation of the gradient of the objective function, a time-dependent adjoint differentiation method is introduced that reduces computation time. Several numerical experiments are performed for small geometry media with embedded inclusions that mimic small animal imaging. In these experiments, the values of the optical coefficients are varied within realistic bounds that are representative of those found in the range of the near-infrared spectrum, including high absorption values. Single and multi-parameter reconstructions (absorption and diffusion coefficients) are performed. The reconstructed images based on the TD-pSPN equations (N > 1) give better estimates of the optical properties of the media than the DE. On the other hand

  4. Natural Silk as a Photonics Component: a Study on Its Light Guiding and Nonlinear Optical Properties

    PubMed Central

    Kujala, Sami; Mannila, Anna; Karvonen, Lasse; Kieu, Khanh; Sun, Zhipei

    2016-01-01

    Silk fibers are expected to become a pathway to biocompatible and bioresorbable waveguides, which could be used to deliver localized optical power for various applications, e.g., optical therapy or imaging inside living tissue. Here, for the first time, the linear and nonlinear optical properties of natural silk fibers have been studied. The waveguiding properties of silk fibroin of largely unprocessed Bombyx mori silkworm silk are assessed using two complementary methods, and found to be on the average 2.8 dB mm−1. The waveguide losses of degummed silk are to a large extent due to scattering from debris on fiber surface and helical twisting of the fiber. Nonlinear optical microscopy reveals both configurational defects such as torsional twisting, and strong symmetry breaking at the center of the fiber, which provides potential for various nonlinear applications. Our results show that nonregenerated B. mori silk can be used for delivering optical power over short distances, when the waveguide needs to be biocompatible and bioresorbable, such as embedding the waveguide inside living tissue. PMID:26926272

  5. Natural Silk as a Photonics Component: a Study on Its Light Guiding and Nonlinear Optical Properties

    NASA Astrophysics Data System (ADS)

    Kujala, Sami; Mannila, Anna; Karvonen, Lasse; Kieu, Khanh; Sun, Zhipei

    2016-03-01

    Silk fibers are expected to become a pathway to biocompatible and bioresorbable waveguides, which could be used to deliver localized optical power for various applications, e.g., optical therapy or imaging inside living tissue. Here, for the first time, the linear and nonlinear optical properties of natural silk fibers have been studied. The waveguiding properties of silk fibroin of largely unprocessed Bombyx mori silkworm silk are assessed using two complementary methods, and found to be on the average 2.8 dB mm-1. The waveguide losses of degummed silk are to a large extent due to scattering from debris on fiber surface and helical twisting of the fiber. Nonlinear optical microscopy reveals both configurational defects such as torsional twisting, and strong symmetry breaking at the center of the fiber, which provides potential for various nonlinear applications. Our results show that nonregenerated B. mori silk can be used for delivering optical power over short distances, when the waveguide needs to be biocompatible and bioresorbable, such as embedding the waveguide inside living tissue.

  6. Natural Silk as a Photonics Component: a Study on Its Light Guiding and Nonlinear Optical Properties.

    PubMed

    Kujala, Sami; Mannila, Anna; Karvonen, Lasse; Kieu, Khanh; Sun, Zhipei

    2016-01-01

    Silk fibers are expected to become a pathway to biocompatible and bioresorbable waveguides, which could be used to deliver localized optical power for various applications, e.g., optical therapy or imaging inside living tissue. Here, for the first time, the linear and nonlinear optical properties of natural silk fibers have been studied. The waveguiding properties of silk fibroin of largely unprocessed Bombyx mori silkworm silk are assessed using two complementary methods, and found to be on the average 2.8 dB mm(-1). The waveguide losses of degummed silk are to a large extent due to scattering from debris on fiber surface and helical twisting of the fiber. Nonlinear optical microscopy reveals both configurational defects such as torsional twisting, and strong symmetry breaking at the center of the fiber, which provides potential for various nonlinear applications. Our results show that nonregenerated B. mori silk can be used for delivering optical power over short distances, when the waveguide needs to be biocompatible and bioresorbable, such as embedding the waveguide inside living tissue. PMID:26926272

  7. Radio and optical interferometric imaging

    NASA Technical Reports Server (NTRS)

    Cornwell, Tim J.

    1992-01-01

    Since diffraction-limited imaging with a single aperture yields angular resolution approx. lambda/D, the attainment of high angular resolution with single apertures requires the construction of correspondingly large monolithic apertures, the whole surface of which must be figured to much less than a wavelength. At the longer wavelengths, it is impossible to build a sufficiently large single aperture: for example, at lambda 21 cm, arcsec resolution requires an aperture of diameter approx. 50 km. At the shorter wavelengths, the atmosphere imposes a natural limit in resolution of about one arcsec. However, another route is possible; that is, using synthetic apertures to image the sky. Synthetic apertures are now in use in many fields, e.g., radio interferometry, radar imaging, and magnetic-resonance imaging. Radio-interferometric techniques developed in radio astronomy over the past 40 years are now being applied to optical and IR astronomical imaging by a number of groups. Furthermore, the problem of figuring synthetic apertures is considerably simpler, and can be implemented in a computer: new 'self-calibration' techniques allow imaging even in the presence of phase errors due to the atmosphere.

  8. Nonlinear optical localization in embedded chalcogenide waveguide arrays

    SciTech Connect

    Li, Mingshan; Huang, Sheng; Wang, Qingqing; Chen, Kevin P.; Petek, Hrvoje

    2014-05-15

    We report the nonlinear optical localization in an embedded waveguide array fabricated in chalcogenide glass. The array, which consists of seven waveguides with circularly symmetric cross sections, is realized by ultrafast laser writing. Light propagation in the chalcogenide waveguide array is studied with near infrared laser pulses centered at 1040 nm. The peak intensity required for nonlinear localization for the 1-cm long waveguide array was 35.1 GW/cm{sup 2}, using 10-nJ pulses with 300-fs pulse width, which is 70 times lower than that reported in fused silica waveguide arrays and with over 7 times shorter interaction distance. Results reported in this paper demonstrated that ultrafast laser writing is a viable tool to produce 3D all-optical switching waveguide circuits in chalcogenide glass.

  9. Applications of ultrafast wavefront rotation in highly nonlinear optics

    NASA Astrophysics Data System (ADS)

    Quéré, F.; Vincenti, H.; Borot, A.; Monchocé, S.; Hammond, T. J.; Taec Kim, Kyung; Wheeler, J. A.; Zhang, Chunmei; Ruchon, T.; Auguste, T.; Hergott, J. F.; Villeneuve, D. M.; Corkum, P. B.; Lopez-Martens, R.

    2014-06-01

    This paper provides an overview of ultrafast wavefront rotation of femtosecond laser pulses and its various applications in highly nonlinear optics, focusing on processes that lead to the generation of high-order harmonics and attosecond pulses. In this context, wavefront rotation can be exploited in different ways, to obtain new light sources for time-resolved studies, called ‘attosecond lighthouses’, to perform time-resolved measurements of nonlinear optical processes, using ‘photonic streaking’, or to track changes in the carrier-envelope relative phase of femtosecond laser pulses. The basic principles are explained qualitatively from different points of view, the experimental evidence obtained so far is summarized, and the perspectives opened by these effects are discussed.

  10. Digital crossbar switch using nonlinear optical ring resonator

    NASA Astrophysics Data System (ADS)

    McAulay, Alastair D.

    2009-08-01

    Optical elements are preferred to electronic ones for military computing and communications to reduce vulnerability to electromagnetic pulses from nuclear explosion, electromagnetic bombs or lightning. Equations are derived for an optical micro ring resonator and for a nonlinear ring resonator that uses Kerr material so that the resonant frequency changes with light intensity in the ring. The switch can be modulated at faster than 10 Gbps for compatibility with electronic switches and equipment. A two-by-two switch is described based on the nonlinear ring resonator. A Benes network is constructed using the two-by-two switches. This allows full permutations of the inputs by means of an algorithm for setting the switches. Several rings are used for each frequency with slightly different frequencies to allow switching of wavelength division multiplexed signals.

  11. Nonlinear dynamics of optical absorption of intense beams

    NASA Astrophysics Data System (ADS)

    Corbett, D.; van Oosten, C. L.; Warner, M.

    2008-07-01

    On traversing materials with absorbing dyes, weak optical beams decay exponentially (a Beer profile), while intense beams develop in time a profile that is spatially linear until at great depth it becomes spatially exponential. This anomalous, deep penetration, due to photobleaching of surface layers, is important for heavy dye loading and intense beams, for instance in photo-actuation. We address the problem of the evolution in time from initial Beer’s Law to a finally deeply-penetrating optical profile in dyes. Our largely analytic solution of the coupled, nonlinear, partial differential equations governing the spatiotemporal decay of the Poynting flux and the nonlinear population dynamics of the photo-active molecules under intense irradiation has application to optomechanical devices.

  12. ZnS/PVA nanocomposites for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Ozga, K.; Michel, J.; Nechyporuk, B. D.; Ebothé, J.; Kityk, I. V.; Albassam, A. A.; El-Naggar, A. M.; Fedorchuk, A. O.

    2016-07-01

    We have found a correlation between ZnS nanocomposite nonlinear optical features and technological processing using electrolytic method. In the earlier researches this factor was neglected. However, it may open a new stage for operation by photovoltaic features of the well known semiconductors within a wide range of magnitudes. The titled nanostructured zinc sulfide (ZnS) was synthesized by electrolytic method. The obtained ZnS nano-crystallites possessed nano-particles sizes varying within 1.6 nm…1.8 nm. The titled samples were analyzed by XRD, HR-TEM, STEM, and nonlinear optical methods such as photo-induced two-photon absorption (TPA) and second harmonic generation (SHG). For this reason the nano-powders were embedded into the photopolymer poly(vinyl) alcohol (PVA) matrices. Role of aggregation in the mentioned properties is discussed. Possible origin of the such correlations are discussed.

  13. A compact nonlinear fiber-based optical autocorrelation peak discriminator.

    PubMed

    Fok, M P; Deng, Y; Prucnal, P R

    2009-06-01

    We experimentally demonstrate a nonlinear fiber-based optical autocorrelation peak discriminator. The approach exploits four-wave mixing in a 37-cm highly-nonlinear bismuth-oxide fiber that provides a passive and compact means for rejecting cross-correlation peaks. The autocorrelation peak discriminator plays an important role in improving the detection of optical CDMA signals. Eye diagrams and bit-error rates are measured at different power ratios. Significant receiver sensitivity improvements are obtained and error-floors are removed. The experimental results show that the autocorrelation peak discriminator works well even when the amplitudes of individual cross-correlation peaks are higher than that of the autocorrelation peak. PMID:19506641

  14. Nonlinear optical properties of lead sulfide nanocrystals in polymeric coatings

    NASA Astrophysics Data System (ADS)

    Lu, S. W.; Sohling, U.; Mennig, M.; Schmidt, H.

    2002-10-01

    Lead sulfide (PbS) nanocrystals with a particle size of 3.3 +/- 0.7 nm have been synthesized in a poly vinyl alcohol (PVA) coating on fused silica glass substrates. The coating was dip-coated from a PVA aqueous solution, in which PbS nanocrystals were precipitated and stabilized in the polymer matrix. Third-order nonlinear optical susceptibility of PbS nanocrystals is dependent on the wavelength with its maximum located near the first excitonic absorption peak resulting from the quantum confinement effect, according to the results of degenerate four wave-mixing. This suggests an enhancement of the nonlinear optical property by excitonic resonance. The maximum figure of merit, χ(3) /α, is as high as 2.91 × 10-12 esu m as measured at 595 nm.

  15. Nonlinear optical properties of metal and semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Whelan, Aine M.; Benrezzak, Sakina; Brennan, Margaret E.; Kelly, John M.; Blau, Werner J.

    2003-03-01

    The synthesis of metal (Au,Ag) and semiconductor (PbS) nanoparticles of specific morphology and shape is reported. The shape of PbS nanoparticles has been varied from spherical to oval to cubic, by use of poly(vinyl alcohol) (PVA), DNA and ethylene glycol as stabilisers respectively. For the first time, a seeding method has been used to successfully prepare PVA stabilised gold and silver nanoparticles. Characterisation of the third order optical nonlinearity of the nanoparticles has been carried out using the Z-scan technique with values of Im ÷ (3) as large as 10-10. Modulation of the magnitude of the nonlinear optical response with morphology in the case of the PbS nanoparticles is presented.

  16. Nonlinear optical properties of methyl red under CW irradiation

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Ye, Qing; Wang, Chen; Wang, Jin; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2015-12-01

    Organic materials have wide potential application in nonlinear optical devices. The nonlinear optical (NLO) properties of methyl red (MR) doped polymethyl methacrylate (MR-PMMA) are investigated under CW laser irradiation at 473 nm, 532 nm and 632.8 nm, respectively. By combining Kramers-Kronig (K-K) relation and CW Z-scan technique, the effective refractive index n2 and the change of refractive index Δn are obtained under different scanning speed at 473 nm and 532 nm. Δn is positive at 473 nm, while Δn is negative at 532 nm. The experimental result is consistent with that of K-K relation. With the scanning speed decreasing, the NLO properties of MR-PMMA are enhanced. With different laser powers at 632.8 nm, MR-PMMA has only nonlinear absorption rather than nonlinear refraction. Meanwhile, the sample is investigated under pulse laser irradiation at 532 nm. Through the comparison of results of CW Z-scan and pulse Z-scan, the influence of the cumulative thermal effect on NLO properties of material is investigated. The results indicate that, under CW irradiation near the absorption peak wavelength, the cumulative thermal effect has great influence to the NLO properties of MR-PMMA.

  17. Third order nonlinear optical properties of bismuth zinc borate glasses

    SciTech Connect

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

    2013-12-28

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi{sub 2}O{sub 3}-30ZnO-(70-x) B{sub 2}O{sub 3} (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (β) and the absorption cross section due to free carriers (σ{sub e}) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  18. Optical bistability of a nondilute suspension of nonlinear coated particles

    NASA Astrophysics Data System (ADS)

    Gu, Liping; Gao, Lei

    2005-11-01

    The intrinsic optical bistability (OB) of a nondilute suspension of coated spherical particles is investigated. We assume both the core and the shell to be nonlinear with third-order nonlinear susceptibilities χc and χs, respectively, and thus the local field in the nonlinear core is not uniform and cannot be obtained exactly. In this connection, we establish the self-consistent mean field approximation, and obtain the spatial average of the local field squared in the nonlinear core (or the shell) as a function of the external applied field. We show that an optical bistable behavior exists only when the structure parameter (λ) is less than the critical one λc, which is dependent on the magnitude of both χc and χs. Moreover, the bistable curves depend strongly on χc and are weakly dependent on χs. In addition, the threshold intensity decreases with increasing λ, and it can be lowered further by using a nondilute volume fraction. The field-dependent effective dielectric function is also studied, and the hysteretic loops are again found.

  19. Diffraction patterns and nonlinear optical properties of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Majles Ara, M. H.; Dehghani, Z.; Sahraei, R.; Daneshfar, A.; Javadi, Z.; Divsar, F.

    2012-03-01

    Stable gold nanoparticles have been prepared by using soluble starch as both the reducing and stabilizing agents; this reaction was carried out at 40 °C for 5 h. The obtained gold nanoparticles were characterized by UV-Vis absorption spectroscopy, transmission electron microscopy (TEM) and z-scan technique. The size of these nanoparticles was found to be in the range of 12-22 nm as analyzed using transmission electron micrographs. The optical properties of gold nanoparticles have been measured showing the surface plasmon resonance. The second-order nonlinear optical (NLO) properties were investigated by using a continuous-wave (CW) He-Ne laser beam with a wavelength of 632.8 nm at three different incident intensities by means of single beam techniques. The nonlinear refractive indices of gold nanoparticles were obtained from close aperture z-scan in order of 10-7 cm2/W. Then, they were compared with diffraction patterns observed in far-field. The nonlinear absorption of these nanoparticles was obtained from open aperture z-scan technique. The values of nonlinear absorption coefficient are obtained in order of 10-1 cm/W.

  20. Nonlinear inverse synthesis technique for optical links with lumped amplification.

    PubMed

    Le, Son Thai; Prilepsky, Jaroslaw E; Turitsyn, Sergei K

    2015-04-01

    The nonlinear inverse synthesis (NIS) method, in which information is encoded directly onto the continuous part of the nonlinear signal spectrum, has been proposed recently as a promising digital signal processing technique for combating fiber nonlinearity impairments. However, because the NIS method is based on the integrability property of the lossless nonlinear Schrödinger equation, the original approach can only be applied directly to optical links with ideal distributed Raman amplification. In this paper, we propose and assess a modified scheme of the NIS method, which can be used effectively in standard optical links with lumped amplifiers, such as, erbium-doped fiber amplifiers (EDFAs). The proposed scheme takes into account the average effect of the fiber loss to obtain an integrable model (lossless path-averaged model) to which the NIS technique is applicable. We found that the error between lossless path-averaged and lossy models increases linearly with transmission distance and input power (measured in dB). We numerically demonstrate the feasibility of the proposed NIS scheme in a burst mode with orthogonal frequency division multiplexing (OFDM) transmission scheme with advanced modulation formats (e.g., QPSK, 16QAM, and 64QAM), showing a performance improvement up to 3.5 dB; these results are comparable to those achievable with multi-step per span digital back-propagation. PMID:25968670

  1. Third order nonlinear optical properties of bismuth zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

    2013-12-01

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi2O3-30ZnO-(70-x) B2O3 (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (β) and the absorption cross section due to free carriers (σe) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  2. Joint photon and wave statistics in nonlinear optical couplers

    NASA Astrophysics Data System (ADS)

    Peřina, Jan; Křepelka, Jaromír

    2014-09-01

    Nonlinear optical couplers based on optical parametric processes and Raman-Brillouin scattering are discussed from the point of view of their nonclassical behaviour using joint photon-number and integrated-intensity probability distributions and derived quantum statistical quantities. Employing these tools quantum entanglement of modes and their nonclassical properties are demonstrated by means of conditional probability distributions and their Fano factors, difference-number probability distributions, quantum oscillations, squeezing of vacuum fluctuations and negative values of the joint wave probability quasidistributions in time evolution. Sub-Poissonian and sub-shot-noise properties are determined for initial coherent, chaotic and squeezed light.

  3. Femtosecond nonlinear fiber optics in the ionization regime.

    PubMed

    Hölzer, P; Chang, W; Travers, J C; Nazarkin, A; Nold, J; Joly, N Y; Saleh, M F; Biancalana, F; Russell, P St J

    2011-11-11

    By using a gas-filled kagome-style photonic crystal fiber, nonlinear fiber optics is studied in the regime of optically induced ionization. The fiber offers low anomalous dispersion over a broad bandwidth and low loss. Sequences of blueshifted pulses are emitted when 65 fs, few-microjoule pulses, corresponding to high-order solitons, are launched into the fiber and undergo self-compression. The experimental results are confirmed by numerical simulations which suggest that free-electron densities of ∼10(17) cm(-3) are achieved at peak intensities of 10(14) W/cm(2) over length scales of several centimeters. PMID:22181732

  4. Nano-imaging collagen by atomic force, near-field and nonlinear microscope

    NASA Astrophysics Data System (ADS)

    Lim, Ken Choong; Tang, Jinkai; Li, Hao; Ng, Boon Ping; Kok, Shaw Wei; Wang, Qijie; Zhang, Ying

    2015-03-01

    As the most abundant protein in the human body, collagen has a very important role in vast numbers of bio-medical applications. The unique second order nonlinear properties of fibrillar collagen make it a very important index in nonlinear optical imaging based disease diagnosis of the brain, skin, liver, colon, kidney, bone, heart and other organs in the human body. The second-order nonlinear susceptibility of collagen has been explored at the macroscopic level and was explained as a volume-averaged molecular hyperpolarizability. However, details about the origin of optical second harmonic signals from collagen fibrils at the molecular level are still not clear. Such information is necessary for accurate interpolation of bio-information from nonlinear optical imaging techniques. The later has shown great potential in collagen based disease diagnosis methodologies. In this paper, we report our work using an atomic force microscope (AFM), near field (SNOM) and nonlinear laser scanning microscope (NLSM) to study the structure of collagen fibrils and other pro-collagen structures.

  5. Nonlinear optical properties of atomic vapor and semiconductors

    SciTech Connect

    Kim, D

    1997-06-01

    This thesis contains the study of highly forbidden resonant second harmonic generation (SHG) in atomic potassium vapor using tunable picosecond pulses. Various output characteristics of vapor SHG have been investigated including the input intensity dependence, potassium vapor density dependence, buffer gas pressure dependence, and spatial profile. Recently, the discovery of new nonlinear optical crystals such as barium borate ({beta}-BaB{sub 2}O{sub 4}, BBO) and lithium borate (LiB{sub 3}O{sub 5}, LBO) has greatly improved the performance of a tunable coherent optical devices based on optical parametric generation and amplification. In the second part of this thesis, a homebuilt picosecond optical parametric generator/amplifier (OPG/OPA) system is described in detail, including its construction details and output characteristics. This laser device has found many useful applications in spectroscopic studies including surface nonlinear optical spectroscopy via sum-frequency generation (SFG). The last part of this thesis reports studies on multiphoton-excited photoluminescence from porous silicon and GaN. Multiphoton excitation and photoluminescence can give numerous complementary information about semiconductors not obtainable with one-photon, above-bandgap excitation.

  6. Nonlinear intersubband optical absorption in a semiconductor quantum well

    NASA Technical Reports Server (NTRS)

    Ahn, D.; Chuang, S. L.

    1987-01-01

    The third-order nonlinear intersubband absorption in a semiconductor quantum well is studied theoretically using the density matrix formalism including intrasubband relaxation. It is shown that the peak absorption is reduced by half for an optical intensity 1 MW/sq cm for the well size L = 126.5 A with 3.0 x 10 to the 16th/cu cm electrons.

  7. Structure, Electronic and Nonlinear Optical Properties of Furyloxazoles and Thienyloxazoles

    NASA Astrophysics Data System (ADS)

    Dagli, Ozlem; Gok, Rabia; Bahat, Mehmet; Ozbay, Akif

    2016-04-01

    Geometry optimization, electronic and nonlinear optical properties of isomers of furyloxazole and thienyloxazole molecules are carried out at the B3LYP/6-311++G(2d,p) level. The conformational analysis of 12 compounds have been studied as a function of torsional angle between rings. Electronic and NLO properties such as dipole moment, energy gap, polarizability and first hyperpolarizability were also calculated.

  8. A few selected applications of surface nonlinear optical spectroscopy.

    PubMed Central

    Shen, Y R

    1996-01-01

    As a second-order nonlinear optical process, sum-frequency generation is highly surface-specific and accordingly has been developed into a very powerful and versatile surface spectroscopic tool. It has found many unique applications in different disciplines and thus provided many exciting new research opportunities in surface and surface-related science. Selected examples are discussed here to illustrate the power of the technique. PMID:8901540

  9. Spatiotemporal nonlinear optics in arrays of subwavelength waveguides

    SciTech Connect

    Gorbach, A. V.; Ding, W.; Staines, O. K.; Nobriga, C. E. de; Hobbs, G. D.; Wadsworth, W. J.; Knight, J. C.; Skryabin, D. V.; Samarelli, A.; Sorel, M.; De La Rue, R. M.

    2010-10-15

    We report numerical and experimental investigations of spatiotemporal nonlinear optical effects leading to spectral broadening in an array of subwavelength silicon waveguides pumped with infrared femtosecond pulses. Adjusting an input pulse position across the array, we observe different patterns in the output spectra. We explain these observations using a theory of the resonant (Cherenkov) radiation emitted by temporal solitons belonging to different spatial supermodes of the array. We also demonstrate strong nonperturbative coupling of temporal dispersion and discrete diffraction in the subwavelength arrays.

  10. Nonlinear electronic polarization and optical response in borophosphate BPO4

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Liu, Qiong; Han, Shujuan; Iitaka, Toshiaki; Su, Haibin; Tohyama, Takami; Jiang, Huaidong; Dong, Yongjun; Yang, Bin; Zhang, Fangfang; Yang, Zhihua; Pan, Shilie

    2016-06-01

    The electronic structure, nonlinear electronic polarization induced by a static external electric field, and frequency dependent second-harmonic susceptibility tensor of the borophosphate BPO4 are studied by a first-principles calculation based on density-functional theory. Our calculated results show that the borophosphate BPO4 has a large band gap ˜10.4 eV, which is larger than the band gap of the widely used nonlinear optical crystal KBe2BO3F2 . However, BPO4 also has a nonlinear coefficient d36=0.92 pm/V at static limit, which also is larger than the nonlinear coefficient d11=0.47 pm/V of KBe2BO3F2 . The unexpected larger nonlinear coefficient of BPO4 can be interpreted by the relatively strong s -p hybridization in BPO4, which can enhance the inter-band Berry connections, while the O 2 p orbitals dominating valence bands in KBe2BO3F2 are very flat, resulting from weak s -p hybridization.

  11. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    NASA Astrophysics Data System (ADS)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  12. Combined optical solitons with parabolic law nonlinearity and spatio-temporal dispersion

    NASA Astrophysics Data System (ADS)

    Zhou, Qin; Zhu, Qiuping

    2015-03-01

    In this work, combined optical solitons are constructed in a weakly nonlocal nonlinear medium. The spatio-temporal dispersion (STD), parabolic law nonlinearity, detuning, nonlinear dispersion as well as inter-modal dispersion are taken into account. The integration tool that is applied is the complex envelope function ansatz. The influences of different parameters on dynamical behavior of combined optical solitons are discussed. The results are useful in describing the propagation of combined optical solitons with STD and parabolic law nonlinearity.

  13. Enhanced nonlinear optics in coupled optical microcavities with an unbroken and broken parity-time symmetry

    NASA Astrophysics Data System (ADS)

    Li, Jiahua; Zhan, Xiaogui; Ding, Chunling; Zhang, Duo; Wu, Ying

    2015-10-01

    We present a perturbation technique to study the linear and nonlinear output characteristics of coherent photon transport in a parity-time (PT )-symmetric double-microcavity system where one passive cavity contains a single quantum emitter. It is found that (i) for the linear transmission of a low-power input probe field, the output spectra of the proposed PT -symmetric system exhibit a single transparent resonance dip and two symmetric, strongly amplifying sidebands, i.e., an inverted dipole-induced transparency; and (ii) for the nonlinear transmission of the input probe field, giant optical third-order nonlinearities with high linear transmission rate and vanishing nonlinear absorption can be achieved efficiently when the system parameters are tuned properly so that a PT -symmetry phase transition occurs. The obtained results can be useful for quantum information processing, quantum nondemolition measurements of photons, and optical signal processing.

  14. Multimodal and non-linear optical microscopy applications in reproductive biology.

    PubMed

    Adur, J; Barbosa, G O; Pelegati, V B; Baratti, M O; Cesar, C L; Casco, V H; Carvalho, H F

    2016-07-01

    A plethora of optical techniques is currently available to obtain non-destructive, contactless, real time information with subcellular spatial resolution to observe cell processes. Each technique has its own unique features for imaging and for obtaining certain biological information. However none of the available techniques can be of universal use. For a comprehensive investigation of biological specimens and events, one needs to use a combination of bioimaging methods, often at the same time. Some modern confocal/multiphoton microscopes provide simultaneous fluorescence, fluorescence lifetime imaging, and four-dimensional imaging. Some of them can also easily be adapted for harmonic generation imaging, and to permit cell manipulation technique. In this work we present a multimodal optical workstation that extends a commercially available confocal microscope to include nonlinear/multiphoton microscopy and optical manipulation/stimulation tools. The nonlinear microscopy capabilities were added to the commercial confocal microscope by exploiting all the flexibility offered by the manufacturer. The various capabilities of this workstation as applied directly to reproductive biology are discussed. Microsc. Res. Tech. 79:567-582, 2016. © 2016 Wiley Periodicals, Inc. PMID:27219203

  15. Wave-Optics Analysis of Pupil Imaging

    NASA Technical Reports Server (NTRS)

    Dean, Bruce H.; Bos, Brent J.

    2006-01-01

    Pupil imaging performance is analyzed from the perspective of physical optics. A multi-plane diffraction model is constructed by propagating the scalar electromagnetic field, surface by surface, along the optical path comprising the pupil imaging optical system. Modeling results are compared with pupil images collected in the laboratory. The experimental setup, although generic for pupil imaging systems in general, has application to the James Webb Space Telescope (JWST) optical system characterization where the pupil images are used as a constraint to the wavefront sensing and control process. Practical design considerations follow from the diffraction modeling which are discussed in the context of the JWST Observatory.

  16. Polycarbonate-Based Blends for Optical Non-linear Applications

    NASA Astrophysics Data System (ADS)

    Stanculescu, F.; Stanculescu, A.

    2016-02-01

    This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.

  17. Polycarbonate-Based Blends for Optical Non-linear Applications.

    PubMed

    Stanculescu, F; Stanculescu, A

    2016-12-01

    This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised. PMID:26873262

  18. First light : from the ruby laser to nonlinear optics

    NASA Astrophysics Data System (ADS)

    Giordmaine, J. A.

    2010-02-01

    Laser action was first demonstrated by Maiman in a flashlamp-pumped ruby crystal in May of 1960. This talk, based in part on personal recollections, recounts some of the research highlights during the two years that followed - a period of exponential growth in the field of quantum electronics, driven by the newly available, unprecedented coherence, power, and monochomaticity of laser light. Active areas from the beginning were new lasers in HeNe and other gas systems, in host crystals with increasingly effective dopants, and in glass. Modes in open resonators became understood, as did the surprising granularity of laser light An important step was the Q-switch, enabling megawatt lasers and providing a new tool for the study of dielectrics at high optical fields. The field of nonlinear optics opened up with experimental discoveries including optical second harmonic generation, two-photon absorption, phase matching and stimulated Raman scattering. A key to subsequent progress was a comprehensive quantum mechanical theory that provided a general description of nonlinear optical processes. The end of the two-year period covered here coincided with two advances which were to shape the future role of lasers in technology and science: the first semiconductor lasers; and a theoretical description of states of light having truly quantum properties, properties not evident in laser light up to that time. )

  19. Optical authentication based on moiré effect of nonlinear gratings in phase space

    NASA Astrophysics Data System (ADS)

    Liao, Meihua; He, Wenqi; Wu, Jiachen; Lu, Dajiang; Liu, Xiaoli; Peng, Xiang

    2015-12-01

    An optical authentication scheme based on the moiré effect of nonlinear gratings in phase space is proposed. According to the phase function relationship of the moiré effect in phase space, an arbitrary authentication image can be encoded into two nonlinear gratings which serve as the authentication lock (AL) and the authentication key (AK). The AL is stored in the authentication system while the AK is assigned to the authorized user. The authentication procedure can be performed using an optoelectronic approach, while the design process is accomplished by a digital approach. Furthermore, this optical authentication scheme can be extended for multiple users with different security levels. The proposed scheme can not only verify the legality of a user identity, but can also discriminate and control the security levels of legal users. Theoretical analysis and simulation experiments are provided to verify the feasibility and effectiveness of the proposed scheme.

  20. Formation of nonlinear holographic images in powerful laser systems.

    PubMed

    Bel'kov, Sergey A; Garanin, Sergey G; Epatko, Igor V; Serov, Rene V; Voronich, Ivan N

    2012-08-20

    The formation of nonlinear holographic images behind a multislab amplifier is studied. The analytical expressions describing magnitudes and locations of intensity maxima depending on the corresponding image number are derived. Comparison with numerical calculations results is given. On the basis of numerical modeling, analysis of gain saturation, slab thickness, and slab aberrations influence is carried out. PMID:22907023

  1. Nonlinear particle behavior during cross-type optical particle separation

    SciTech Connect

    Kim, Sang Bok; Lee, Kyung Heon; Sung, Hyung Jin; Kim, Sang Soo

    2009-12-28

    The effects of varying the ratio of the optical force to the viscous drag force, termed S, on cross-type optical particle separation were investigated experimentally to test previous theoretical predictions. The experiments were performed for various flow velocities, powers of the laser beam, and radii of the laser beam waist and the particles. The behaviors of the particles during optical separation were examined by measuring the retention distances and analyzing the particle trajectories. For small values of S, the particles move with constant velocity in the flow direction and the retention distance increases linearly with S. However, the particles accelerate and decelerate within the laser beam and the retention distance increases nonlinearly with S when S increases further.

  2. All-optical nonlinear plasmonic ring resonator switches

    NASA Astrophysics Data System (ADS)

    Nozhat, N.; Granpayeh, N.

    2014-11-01

    In this paper, all-optical nonlinear plasmonic ring resonator (PRR) switches containing 90o sharp and smooth bends have been proposed and numerically analyzed by the finite-difference time-domain method. Kerr nonlinear self-phase modulation (SPM) and cross-phase modulation (XPM) effects on the switching performance of the device have been studied. By applying a high-power lightwave, the signal can switch from one port to the other port due to the ON/OFF resonant states of the ring. We have shown that by utilizing the XPM effect, the output power ratio is improved by a factor of 2.5 and the required switching power is 31% of that of the case with only the SPM effect. Moreover, by utilizing sharp bend square-shaped ring resonators, the switching power is 10.4% lower than that of the smooth ones. The nonlinear PRR switches are suitable for application in photonic-integrated circuits as all-optical switches because of their nanoscale size and low required switching power.

  3. Optical imaging: Ultrafast buffering by molecular gas

    NASA Astrophysics Data System (ADS)

    Hertz, Edouard; Lavorel, Bruno; Faucher, Olivier

    2011-02-01

    A simple molecular gas sample can be used to achieve ultrafast optical buffering in two-dimensional optical imaging, thus serving as a promising extension of the well-developed liquid-crystal display technology.

  4. PREFACE: Ultrafast and nonlinear optics in carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Kono, Junichiro

    2013-02-01

    Carbon-based nanomaterials—single-wall carbon nanotubes (SWCNTs) and graphene, in particular—have emerged in the last decade as novel low-dimensional systems with extraordinary properties. Because they are direct-bandgap systems, SWCNTs are one of the leading candidates to unify electronic and optical functions in nanoscale circuitry; their diameter-dependent bandgaps can be utilized for multi-wavelength devices. Graphene's ultrahigh carrier mobilities are promising for high-frequency electronic devices, while, at the same time, it is predicted to have ideal properties for terahertz generation and detection due to its unique zero-gap, zero-mass band structure. There have been a large number of basic optical studies on these materials, but most of them were performed in the weak-excitation, quasi-equilibrium regime. In order to probe and assess their performance characteristics as optoelectronic materials under device-operating conditions, it is crucial to strongly drive them and examine their optical properties in highly non-equilibrium situations and with ultrashot time resolution. In this section, the reader will find the latest results in this rapidly growing field of research. We have assembled contributions from some of the leading experts in ultrafast and nonlinear optical spectroscopy of carbon-based nanomaterials. Specific topics featured include: thermalization, cooling, and recombination dynamics of photo-generated carriers; stimulated emission, gain, and amplification; ultrafast photoluminescence; coherent phonon dynamics; exciton-phonon and exciton-plasmon interactions; exciton-exciton annihilation and Auger processes; spontaneous and stimulated emission of terahertz radiation; four-wave mixing and harmonic generation; ultrafast photocurrents; the AC Stark and Franz-Keldysh effects; and non-perturbative light-mater coupling. We would like to express our sincere thanks to those who contributed their latest results to this special section, and the

  5. All-optical nonlinear holographic correlation using bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Thoma, Ralph; Dratz, Michael; Hampp, Norbert

    1995-05-01

    Films made of the halobacterial photochrome bacteriorhodopsin (BR) can be used in a number of holographic real-time applications. Their application as active material in a dual-axis joint- Fourier-transform (DAJFT) real-time correlator was shown recently. The BR films have a strong nonlinear intensity dependence on the light-induced absorption and refractive-index changes. Therefore the holographic diffraction efficiency also shows a nonlinear dependence on the writing intensity. We investigate the effect of this nonlinearity on the result of the correlation process in a bacteriorhodopsin-based DAJFT correlator. Numerical models supporting the experimental observations are presented. It was found that the BR film combines the holographic function for most objects with that of a spatial bandpass filter, whose center frequency is tuned by the writing intensity. This results in smaller peak widths and a suppression of the sidelobes. BR films allow the application of this nonlinear behavior in real time to the all-optical correlation process.

  6. Nonlinear optical processing with Fabry-Perot interferometers containing phase recording media

    NASA Technical Reports Server (NTRS)

    Bartholomew, B. J.; Lee, S. H.

    1980-01-01

    New techniques in nonlinear optical processing are explored, based on the operation of intensity level selection as performed by a Fabry-Perot interferometer containing a phase object. The image being processed is recorded on a medium between the mirrors as a spatially varying phase shift less than pi. The interferometer only transmits light through those portions of the object that corresponds to a single value of the phase and hence to a single intensity level in the input. More complicated operations such as thresholding and analog-to-digital conversion are performed by modulating the light source as the different levels are selected. Photoresist and lithium niobate have been used as phase objects, and experimental data for both are presented. Three kinds of Fabry-Perot interferometers have been used to demonstrate nonlinear processing using coherent and incoherent light. Color images have been produced with black and white inputs and white light illumination.

  7. Nonlinear optical security system with a modified amplitude phase retrieval algorithm

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Quan, Chenggen; Tay, Cho Jui

    2015-03-01

    A new nonlinear optical image encryption scheme based on a modified amplitude phase retrieval algorithm is proposed. With two random phase masks that serve as the public encryption keys, one iterative amplitude and phase retrieval process is employed to encode the primary image into a stationary white noise. The two private keys generated in the encryption process are randomly distributed binary matrices to be used to perform one-way binary phase modulations. The proposed encryption process is nonlinear and offers enhanced security. Numerical simulations are presented to demonstrate the feasibility and security of the proposed system. The results also illustrate that the computing efficiency of the algorithm is improved and the number of iterations is much less than that of cryptosystem based on Yang-Gu algorithm, which has two iteration processes.

  8. Reflective optical imaging method and circuit

    DOEpatents

    Shafer, David R.

    2001-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements are characterized in order from object to image as convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention increases the slit dimensions associated with ringfield scanning optics, improves wafer throughput and allows higher semiconductor device density.

  9. Origin of optical bistability and hysteretic reflectivity on account of nonlinearity at optically induced gallium silica interface

    NASA Astrophysics Data System (ADS)

    Sharma, Arvind; Nagar, A. K.

    2016-05-01

    The origin of optical bistability and hysterectic reflectivity on account of nonlinearity at optically induced Gallium silica interface has been investigated. Assuming the wave to be incident from the gallium nano particle layer side at gallium silica interface. The coupling between incident and reflected waves has shown nonlinear effects on Snell's law and Fresnel law. Effect of these nonlinear processes optical bistability and hysterectic reflectivity theoretically has been investigated. Theoretical results obtained are consistent with the available experimental results.

  10. Highly Non-Linear Optical (NLO) organic crystals and films. Electrooptical organic materials

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Rosenberger, Franz; Matthews, John

    1987-01-01

    Devices employing nonlinear optics (NLO) hold great promise for important applications in integrated optics, optical information processing and telecommunications. Properly designed organics possess outstanding optical and electrooptical properties which will substantially advance many technologies including electrooptical switching, optical amplification for communications, and parallel processing for hybrid optical computers. A brief comparison of organic and inorganic materials is given.

  11. Convexity properties of images under nonlinear integral operators

    SciTech Connect

    Kokurin, M Yu

    2014-12-31

    Conditions are obtained for the image of a given set under a general completely continuous nonlinear integral operator to have convex closure. These results are used to establish the uniqueness of quasi-solutions of nonlinear integral equations of the first kind and to prove the solvability of equations of the first kind on a dense subset of the right-hand sides. Bibliography: 11 titles.

  12. Application and Miniaturization of Linear and Nonlinear Raman Microscopy for Biomedical Imaging

    NASA Astrophysics Data System (ADS)

    Mittal, Richa

    Current diagnostics for several disorders rely on surgical biopsy or evaluation of ex vivo bodily fluids, which have numerous drawbacks. We evaluated the potential for vibrational techniques (both linear and nonlinear Raman) as a reliable and noninvasive diagnostic tool. Raman spectroscopy is an optical technique for molecular analysis that has been used extensively in various biomedical applications. Based on demonstrated capabilities of Raman spectroscopy we evaluated the potential of the technique for providing a noninvasive diagnosis of mucopolysaccharidosis (MPS). These studies show that Raman spectroscopy can detect subtle changes in tissue biochemistry. In applications where sub-micrometer visualization of tissue compositional change is required, a transition from spectroscopy to high quality imaging is necessary. Nonlinear vibrational microscopy is sensitive to the same molecular vibrations as linear Raman, but features fast imaging capabilities. Coherent Raman scattering when combined with other nonlinear optical (NLO) techniques (like two-photon excited fluorescence and second harmonic generation) forms a collection of advanced optical techniques that provide noninvasive chemical contrast at submicron resolution. This capability to examine tissues without external molecular agents is driving the NLO approach towards clinical applications. However, the unique imaging capabilities of NLO microscopy are accompanied by complex instrument requirements. Clinical examination requires portable imaging systems for rapid inspection of tissues. Optical components utilized in NLO microscopy would then need substantial miniaturization and optimization to enable in vivo use. The challenges in designing compact microscope objective lenses and laser beam scanning mechanisms are discussed. The development of multimodal NLO probes for imaging oral cavity tissue is presented. Our prototype has been examined for ex vivo tissue imaging based on intrinsic fluorescence and SHG

  13. Third- and fifth-order optical nonlinearities in organic materials

    NASA Astrophysics Data System (ADS)

    Said, A. A.; Wamsley, C.; Hagan, D. J.; Van Stryland, E. W.; Reinhardt, Bruce A.; Roderer, Paul; Dillard, Ann G.

    1994-10-01

    We measure the nonlinear optical properties of solutions of a bisbenzethiozole-substituted thiophene compound (BBTDOT) and didecyloxy substituted polyphenyl (DDOS) using the Z-scan technique with 532 nm picosecond pulses. Both compounds exhibit two-photon absorption (2PA) and excited-state absorption (ESA) from the 2PA generated excited states. We measure the magnitude and sign of the real (refractive) and imaginary (2PA) parts of the third-order hyperpolarizability, and the excited-state absorptive and refractive cross sections. We observe third-order self-focusing in BBTDOT and self-defocusing in DDOS while both show excited-state defocusing. All these effects were previously observed and modeled in semiconductors giving insight into the nonlinearities occurring in these organic materials.

  14. The nonlinear optical rectification coefficient in a hydrogenic quantum ring

    NASA Astrophysics Data System (ADS)

    Xie, Wenfang

    2012-05-01

    The second-order nonlinear optical rectification coefficient (ORC) associated with intersubband transitions in a hydrogenic quantum ring (QR) with a two-dimensional pseudopotential in the presence of an external magnetic field is theoretically investigated. Calculations are performed by using the perturbation method and the compact density-matrix approach within the effective mass approximation. Based on the computed energies and wave functions, we have investigated the effects of the hydrogenic impurity, an external magnetic field, the geometrical size and the chemical potential of the pseudopential on this coefficient. Our results show that the second-order nonlinear ORCs of a hydrogenic QR are strongly affected by the geometrical size and chemical potential of the pseudopential, the hydrogenic impurity and the external magnetic field.

  15. Planar Waveguides Formed by Ag Na Ion Exchange in Nonlinear Optical Glasses: Diffusion and Optical Properties

    NASA Astrophysics Data System (ADS)

    Martin, Marc; Videau, Jean J.; Canioni, Lionel; Adamietz, Frédéric; Sarger, Laurent; Le Flem, Gilles

    2000-01-01

    All-optical communication systems are the subject of intense research related to the integration of nonlinear optical materials. In sodiocalcic borophosphate glasses that contain niobium oxide and exhibit high nonlinear optical indices, planar waveguides have been formed by a Ag Na ion-exchange technique. WKB analysis has been used to characterize the diffusion profiles of silver ions exchanged in glass substrate samples chemically by an electron microprobe technique and optically by an M -line technique. These methods permit the Ag penetration depth and diffusion profile shape and index profiles to be determined. The results are analyzed and discussed in relation to Ca 2 concentration and exchange conditions in glasses. The Ag diffusion in these glasses can be almost entirely controlled for index-profile engineering.

  16. Nonlinear optical properties of colloidal silver nanoparticles produced by laser ablation in liquids

    SciTech Connect

    Karavanskii, V A; Krasovskii, V I; Ivanchenko, P V; Simakin, Aleksandr V

    2004-07-31

    The optical and nonlinear optical properties of colloidal solutions of silver obtained by laser ablation in water and ethanol are studied. It is shown that freshly prepared colloids experience a full or partial sedimentation by changing their nonlinear optical properties. Aqueous colloids undergo a partial sedimentation and their nonlinear optical absorption changes to nonlinear optical transmission. The obtained results are interpreted using the Drude model for metal particles taking the particle size into account and can be explained by the sedimentation of larger silver particles accompanied by the formation of a stable colloid containing silver nanoparticles with a tentatively silver oxide shell. The characteristic size of particles forming such a stable colloid is determined and its optical nonlinearity is estimated. (nonlinear optical phenomena)

  17. Nonlinear frequency-mixing photoacoustic imaging of a crack

    NASA Astrophysics Data System (ADS)

    Chigarev, N.; Zakrzewski, J.; Tournat, V.; Gusev, V.

    2009-08-01

    We present a technique for nonlinear photoacoustic imaging of cracks by laser excitation with intensity modulation at two fundamental frequencies combined with detection at mixed frequencies. By exploiting the strong dependence of the photoacoustic emission efficiency on the state—open or closed—of the contacts between the crack faces, remarkably enhanced image contrast is observed, ˜20 times higher than in linear photoacoustic images at the highest of the fundamental frequencies.

  18. Nonlinear optical studies of aqueous interfaces, polymers, and nanowires

    NASA Astrophysics Data System (ADS)

    Onorato, Robert Michael

    -transfer-to-solvent band and a Langmuir adsorption model are used to determine the affinity of bromide for both the air/water and dodecanol/water interfaces in the molar concentration regime. The Gibbs free energy of adsorption for the former is determined to be -1.4 kJ/mol with a lower 90% confidence limit of -4.1 kJ/mol. For the dodecanol/water interface the data are best fit with a Gibbs free energy of +8 kJ/mol with an estimated a lower limit of -4 kJ/mol. Adsorption of ions to the air/water interface in the millimolar regime is a particularly interesting phenomenon. In Chapter 4, the affinity of sodium chloride and sodium bromide to the air/water interface is probed by UV-SHG. Both salts exhibit a strong adsorption, with free energies greater than -20 kJ/mol. Interestingly, sodium chloride exhibits a stronger affinity for the interface than does sodium iodide, which was previously studied by Poul Peterson. This is counter to both experimental and theoretical results for higher concentrations. It has been predicted that ion adsorption is dictated by strong and opposing electrostatic and entropic forces. The change in order of ion interfacial affinity can be explained by relatively small changes in these forces at different concentrations and ionic strengths. In Chapters 5 and 6, other work using nonlinear optical techniques is described. Coherent anti-Stokes Raman scattering microscopy is a promising tool for chemically selective imaging based on molecular vibrations. While CARS is currently used as a biological imaging tool, many variations are still being developed, perhaps the most important being multiplex CARS microscopy. Multiplex CARS has the advantage of comparing images based on different molecular vibrations without changing the excitation wavelengths. In Chapter 5, I demonstrate both high spectral and spatial resolution multiplex CARS imaging of polymer films using a simple scheme for chirped CARS with a spectral bandwidth of 300 cm-1. In Chapter 6, the nonlinear optical

  19. Nonlinear elastic wave tomography for the imaging of corrosion damage.

    PubMed

    Ciampa, Francesco; Scarselli, Gennaro; Pickering, Simon; Meo, M

    2015-09-01

    This paper presents a nonlinear elastic wave tomography method, based on ultrasonic guided waves, for the image of nonlinear signatures in the dynamic response of a damaged isotropic structure. The proposed technique relies on a combination of high order statistics and a radial basis function approach. The bicoherence of ultrasonic waveforms originated by a harmonic excitation was used to characterise the second order nonlinear signature contained in the measured signals due to the presence of surface corrosion. Then, a radial basis function interpolation was employed to achieve an effective visualisation of the damage over the panel using only a limited number of receiver sensors. The robustness of the proposed nonlinear imaging method was experimentally demonstrated on a damaged 2024 aluminium panel, and the nonlinear source location was detected with a high level of accuracy, even with few receiving elements. Compared to five standard ultrasonic imaging methods, this nonlinear tomography technique does not require any baseline with the undamaged structure for the evaluation of the corrosion damage, nor a priori knowledge of the mechanical properties of the specimen. PMID:26044196

  20. Reflective optical imaging system with balanced distortion

    DOEpatents

    Chapman, Henry N.; Hudyma, Russell M.; Shafer, David R.; Sweeney, Donald W.

    1999-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  1. Synthesis and characterization of a family of nonlinear optical materials

    NASA Astrophysics Data System (ADS)

    Brott, Lawrence Langenbach

    The development of nonlinear optical (NLO) materials represents an exciting field with applications in areas such as optical signal processing and coherent laser light generation. Second-order NLO chromophore containing materials are being used as frequency doublers or electro-optical modulators while third order NLO chromophores are being designed with large two-photon absorption coefficients for upconverted lasing and imaging applications. This dissertation describes the synthesis and characterization of a group of NLO chromophores containing aromatic heterocyclic rings as π-electron donors, acceptors, and bridging groups. Thiophene, 3,4- ethylenedioxythiophene (EDOT), and diphenyl amine were used here as the electron donor groups while pyridine was used as the electron acceptor. Fluorene ring units were incorporated as aromatic π-electron bridging groups with n-decyl or ethyl chains attached at the C-9 position of the fluorene in order to promote solubility in common organic solvents. One asymmetrical chromophore was made via a three step technique in which a thiophene- and pyridine-propargyl amine reacted with a 2,7-(bisallylbromide)fluorene to form a salt. The bonds underwent a Stevens rearrangement after the addition of a base and finally were thermally cyclized to create a new phenyl ring. Consequently, a new chromophore was made resulting in a molecule with a thiophene and pyridine group separated by four phenyl rings. Other chromophores were made with carbon-carbon bond formation via a Stille coupling process. Thiophene, EDOT, and pyridine rings were functionalized with tributyltin groups, and the resulting molecules coupled with halogenated di-n-decyl-fluorenes. Two asymmetrical chromophores were made using a thiophene and pyridine as the π-electron donor and acceptor rings, respectively, and either one or two fluorene groups as the π-electron bridge. Three symmetrical chromophores were also made in the same manner to yield molecules with thiophene

  2. Nonlinear optics of Bloch oscillating electrons in semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Ghosh, Avik

    A quantum particle in a periodic potential can exhibit rich dynamics in a driving field. In particular, Bloch oscillation of electrons in a superlattice leads to optical properties that are nonlinear functions of the input fields. In a DC field, we analyze the coupling of Bloch oscillations in a superlattice with plasmons and longitudinal optical (LO) phonons, modelled by a pendulum linearly coupled to an oscillator. In the absence of LO phonons, the pendulum equation predicts a sharp transition from plasma oscillations to Bloch oscillations at a critical density or electric field. Resonant Bloch-phonon coupling enhances the phonon amplitude and generates sidebands, but produces no gap in the Bloch-phonon spectrum. Our predictions qualitatively agree with recent experimental results. Considerably more dramatic is the response of charges to an oscillatory incident field. In an AC field, the resonance between the external frequency and the Bloch oscillation frequency set by the field amplitude makes the optical response a nonlinear function of the field amplitude. At certain discrete values of the AC amplitude the electron is dynamically localized, whereupon the total current density decreases drastically while the power dissipated is maximized. The THz reflection coefficient vanishes at dynamic localization, and thus oscillates with varying AC field amplitude inside the superlattice. At high doping, the nonlinear transformation between the fields inside and outside the superlattice leads furthermore to multistability in the optical properties as a function of the incident field. Similar oscillations and multistability exist for third harmonic power generated by a set of superlattices fabricated into a quasi-optical array. The generated power can be optimized by bringing the harmonics into Fabry-Perot resonance with the substrate. We compare our predictions with recent experimental results for a quasi-optical array. Combining a mixture of DC and AC fields leads to

  3. Advances in optical imaging for pharmacological studies

    PubMed Central

    Arranz, Alicia; Ripoll, Jorge

    2015-01-01

    Imaging approaches are an essential tool for following up over time representative parameters of in vivo models, providing useful information in pharmacological studies. Main advantages of optical imaging approaches compared to other imaging methods are their safety, straight-forward use and cost-effectiveness. A main drawback, however, is having to deal with the presence of high scattering and high absorption in living tissues. Depending on how these issues are addressed, three different modalities can be differentiated: planar imaging (including fluorescence and bioluminescence in vivo imaging), optical tomography, and optoacoustic approaches. In this review we describe the latest advances in optical in vivo imaging with pharmacological applications, with special focus on the development of new optical imaging probes in order to overcome the strong absorption introduced by different tissue components, especially hemoglobin, and the development of multimodal imaging systems in order to overcome the resolution limitations imposed by scattering. PMID:26441646

  4. Ionic and electronic processes in non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, Igor N.; Yakovlev, Victor Yu.

    2005-01-01

    The paper presents the results of a study of the formation and decay of lattice defects in nonlinear optical crystals of NH4H2PO4 (ADP), KH2PO4 (KDP), Li2B4O7 (LTB) and LiB3O5 (LBO) with a sublattice of mobile hydrogen (ADP, KDP) and lithium (LTB, LBO) cations. By means of the luminescent and absorption optical spectroscopy with (the) a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption of these crystals in the visible and UV spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect radiationless tunnel recombination between the trapped hole center and the H0 and Li0 electron trapped centers. At 290 K, the H0 and Li0 centers are subject to thermally stimulated migration. All manifestations of a radiative recombination observed in these crystals are accounted for by the involvement of additional electronic and hole centers of a different nature in the recombination process.

  5. Topological charge algebra of optical vortices in nonlinear interactions

    NASA Astrophysics Data System (ADS)

    Shutova, Mariia; Zhdanova, Alexandra; Bahari, Aysan; Zhi, Miaochan; Sokolov, Alexei

    2016-05-01

    Optical vortices find their use in multiple areas of research and technology; in particular, they provide an opportunity to generate short-pulse spatially-structured optical beams, which can be used to study ultrafast processes. In our work, we explore interactions of femtosecond optical vortices in nonlinear crystals. We investigate the transfer of orbital angular momentum among multiple (applied and generated) beams involved in a coherent Raman interaction. We use a liquid crystal light modulator to shape the applied pump and Stokes beams into optical vortices with various integer values of topological charge, and cross them in a Raman-active crystal to produce multiple Stokes and anti-Stokes sidebands. We then examine the transfer of optical angular momentum into each sideband and find that it follows a certain law that can be derived from angular momentum conservation for created and annihilated photons, or equivalently, from phase-matching considerations for the interacting beams. Presenter is supported by the Herman F. Heep and Minnie Belle Heep Texas A&M University Endowed Fund administered by the Texas A&M Foundation

  6. Optically controlled microwave phase shifter based on nonlinear polarization rotation in a highly nonlinear fiber.

    PubMed

    Li, Wei; Sun, Wen Hui; Wang, Wen Ting; Zhu, Ning Hua

    2014-06-01

    This Letter reports an optically controlled microwave phase shifter with an ultra-wideband working bandwidth and a full 360° phase shifting range based on nonlinear polarization rotation (NPR) in a highly nonlinear fiber (HNLF). A continuous wave probe light is modulated by a polarization modulator (PolM) that is driven by a microwave signal to be phase shifted. The optical carrier and the first-order sidebands of the probe light experience different phase shifts due to the NPR induced by the control light in the HNLF. An optical bandpass filter is used to realize single-sideband modulation of the probe light by removing one of the first-order sidebands, as well as to reject the control light. After detecting by a photodetector, the phase of the recovered microwave signal is continuously tunable by adjusting the power of the control light. The proposed approach is theoretically analyzed and experimentally verified. A full 360° tunable phase shift is realized over an ultra-wideband frequency range from 8 to 38 GHz when the power of the control light is tuned from 0 to 570 mW. PMID:24876035

  7. Measurement and control of optical nonlinearities of importance to glass laser fusion systems

    NASA Astrophysics Data System (ADS)

    Kurnit, Norman A.; Shimada, Tsutomu; Sorem, Michael S.; Taylor, Antoinette J.; Rodriguez, George; Clement, Tracy S.; Fearn, Heidi; James, Daniel F.; Milonni, Peter W.

    1997-12-01

    Experimental and theoretical studies at Los Alamos of nonlinear optical phenomena important to the design of the National Ignition Facility are summarized. These include measurements of nonlinear index coefficients, Raman scattering in atmospheric oxygen, and theoretical studies of harmonic conversion.

  8. Z-scan: A simple technique for determination of third-order optical nonlinearity

    SciTech Connect

    Singh, Vijender; Aghamkar, Praveen

    2015-08-28

    Z-scan is a simple experimental technique to measure intensity dependent nonlinear susceptibilities of third-order nonlinear optical materials. This technique is used to measure the sign and magnitude of both real and imaginary part of the third order nonlinear susceptibility (χ{sup (3)}) of nonlinear optical materials. In this paper, we investigate third-order nonlinear optical properties of Ag-polymer composite film by using single beam z-scan technique with Q-switched, frequency doubled Nd: YAG laser (λ=532 nm) at 5 ns pulse. The values of nonlinear absorption coefficient (β), nonlinear refractive index (n{sub 2}) and third-order nonlinear optical susceptibility (χ{sup (3)}) of permethylazine were found to be 9.64 × 10{sup −7} cm/W, 8.55 × 10{sup −12} cm{sup 2}/W and 5.48 × 10{sup −10} esu, respectively.

  9. Few-cycle dissipative solitons in active nonlinear optical fibres

    SciTech Connect

    Rosanov, N N; Semenov, V E; Vysotina, N V

    2008-02-28

    The propagation of self-induced transparency video pulses is studied in a waveguide containing two-level atoms of two types, which can either amplify or absorb pulses. It is shown that the amplified pulse can be compressed down to the duration comparable with the inverse frequency of the atomic transition (a few femtoseconds) along with the increase in the peak amplitude. The mechanisms restricting the compression of amplified self-induced transparency pulses are analysed (the introduction of the third atomic level and the use of the Bragg grating of the waveguide refractive index). (nonlinear optical phenomena)

  10. Integrable nonlinear parity-time-symmetric optical oscillator

    NASA Astrophysics Data System (ADS)

    Hassan, Absar U.; Hodaei, Hossein; Miri, Mohammad-Ali; Khajavikhan, Mercedeh; Christodoulides, Demetrios N.

    2016-04-01

    The nonlinear dynamics of a balanced parity-time-symmetric optical microring arrangement are analytically investigated. By considering gain and loss saturation effects, the pertinent conservation laws are explicitly obtained in the Stokes domain, thus establishing integrability. Our analysis indicates the existence of two regimes of oscillatory dynamics and frequency locking, both of which are analogous to those expected in linear parity-time-symmetric systems. Unlike other saturable parity-time-symmetric systems considered before, the model studied in this work first operates in the symmetric regime and then enters the broken parity-time phase.

  11. Theoretical study of nonlinear optical properties of oxocarbon derivatives

    NASA Astrophysics Data System (ADS)

    Junqueira, G. M. A.; Faria, M. S.; da Silva, A. M.; Dos Santos, H. F.

    In this work, first hyperpolarizability (β) and electronic spectra were obtained at ab initio and semiempirical levels of theory for mono- and bi-squarate derivatives. The results from our calculations suggest the investigated compounds as potential molecules for nonlinear optics (NLO). By means of the employed theoretical methodology, it was possible to identify structural aspects leading to enhancement of the NLO properties of the studied oxocarbons. Furthermore, a correlation between Hammett parameters of the substituents (∑σp) and ln (βtot) was established.

  12. Optical pattern formation with a two-level nonlinearity

    NASA Astrophysics Data System (ADS)

    Camara, A.; Kaiser, R.; Labeyrie, G.; Firth, W. J.; Oppo, G.-L.; Robb, G. R. M.; Arnold, A. S.; Ackemann, T.

    2015-07-01

    We present an experimental and theoretical investigation of spontaneous pattern formation in the transverse section of a single retroreflected laser beam passing through a cloud of cold rubidium atoms. In contrast to previously investigated systems, the nonlinearity at work here is that of a two-level atom, which realizes the paradigmatic situation considered in many theoretical studies of optical pattern formation. In particular, we are able to observe the disappearance of the patterns at high intensity due to the intrinsic saturable character of two-level atomic transitions.

  13. 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.

  14. Tuning nonlinear optical absorption properties of WS2 nanosheets

    NASA Astrophysics Data System (ADS)

    Long, Hui; Tao, Lili; Tang, Chun Yin; Zhou, Bo; Zhao, Yuda; Zeng, Longhui; Yu, Siu Fung; Lau, Shu Ping; Chai, Yang; Tsang, Yuen Hong

    2015-10-01

    To control the optical properties of two-dimensional (2D) materials is a long-standing goal, being of both fundamental and technological significance. Tuning nonlinear optical absorption (NOA) properties of 2D transition metal dichalcogenides in a cost effective way has emerged as an important research topic because of its possibility to custom design NOA properties, implying enormous applications including optical computers, communications, bioimaging, and so on. In this study, WS2 with different size and thickness distributions was fabricated. The results demonstrate that both NOA onset threshold, FON, and optical limiting threshold, FOL, of WS2 under the excitation of a nanosecond pulsed laser can be tuned over a wide range by controlling its size and thickness. The FON and FOL show a rapid decline with the decrease of size and thickness. Due to the edge and quantum confinement effect, WS2 quantum dots (2.35 nm) exhibit the lowest FON (0.01 J cm-2) and FOL (0.062 J cm-2) among all the samples, which are comparable to the lowest threshold achieved in graphene based materials, showing great potential as NOA materials with tunable properties.To control the optical properties of two-dimensional (2D) materials is a long-standing goal, being of both fundamental and technological significance. Tuning nonlinear optical absorption (NOA) properties of 2D transition metal dichalcogenides in a cost effective way has emerged as an important research topic because of its possibility to custom design NOA properties, implying enormous applications including optical computers, communications, bioimaging, and so on. In this study, WS2 with different size and thickness distributions was fabricated. The results demonstrate that both NOA onset threshold, FON, and optical limiting threshold, FOL, of WS2 under the excitation of a nanosecond pulsed laser can be tuned over a wide range by controlling its size and thickness. The FON and FOL show a rapid decline with the decrease of size

  15. The Impact of Fiber Nonlinearities on Digital Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Chiang, Ting-Kuang

    Wavelength-division multiplexing (WDM) enables high throughput fiber-optic networks by sending several optical channels through a single fiber. Even though the bandwidth of optical fibers is over 25 THz, fiber nonlinearities can limit the capacity of WDM communication systems. Cross -phase modulation (XPM) is one of the nonlinear effects that affect WDM systems. This thesis provides an in-depth understanding of the properties of XPM-induced phase shift and suggests techniques to suppress XPM in long-distance WDM optical networks. In this thesis, XPM is theoretically and experimentally investigated in fiber links with optical amplifiers and dispersion compensators. The theoretical analysis suggests that the XPM effect can be modeled as a phase modulator with inputs from the intensity of co-propagating waves. The frequency response of the phase modulator depends on fiber dispersion, wavelength separation, and fiber length. In non-dispersive fibers, XPM is frequency-independent; in dispersive fibers, the response is approximately inversely proportional to modulation frequency, fiber dispersion, and wavelength separation. In N-segment amplified links with no dispersion compensators, the XPM frequency response is increased N -fold, but only in very narrow frequency bands. In most other frequency bands, the increase is limited and almost independent of N. However, in N-segment amplified links with dispersion compensators, the frequency response of XPM is increased N-fold at all frequencies if the dispersion is compensated for within each fiber segment. The XPM-induced sensitivity penalty in multichannel continuous-phase frequency-shift-keying optical communication systems is investigated by theoretical analysis, computer simulations, and experimental measurements. It is shown that high-frequency components in the XPM-induced phase shift play a more important role in determining the sensitivity penalty than the low-frequency components. The XPM-induced sensitivity penalty

  16. Image enhancement by non-linear extrapolation in frequency space

    NASA Technical Reports Server (NTRS)

    Anderson, Charles H. (Inventor); Greenspan, Hayit K. (Inventor)

    1998-01-01

    An input image is enhanced to include spatial frequency components having frequencies higher than those in an input image. To this end, an edge map is generated from the input image using a high band pass filtering technique. An enhancing map is subsequently generated from the edge map, with the enhanced map having spatial frequencies exceeding an initial maximum spatial frequency of the input image. The enhanced map is generated by applying a non-linear operator to the edge map in a manner which preserves the phase transitions of the edges of the input image. The enhanced map is added to the input image to achieve a resulting image having spatial frequencies greater than those in the input image. Simplicity of computations and ease of implementation allow for image sharpening after enlargement and for real-time applications such as videophones, advanced definition television, zooming, and restoration of old motion pictures.

  17. Nonlinear optical transmission of an integrated optical bent coupler in semiconductor-doped glass

    NASA Astrophysics Data System (ADS)

    Guntau, Matthias; Possner, Torsten; Braeuer, Andreas H.; Dannberg, Peter

    1991-08-01

    A technology for monomode slab and strip waveguide fabrication in semiconductor-doped glasses (SDG) is presented. On this basis, directional couplers consisting of both parallel (DC) and bent (BC) couplers of strip waveguides were realized. The optically linear and nonlinear behavior of these devices is described.

  18. Dual-control nonlinear-optical loop mirrors for all-optical soliton synchronous modulation

    NASA Astrophysics Data System (ADS)

    Bigo, Sébastien; Desurvire, Emmanuel; Audouin, Olivier

    1996-09-01

    A novel dual-control configuration of nonlinear loop mirrors is used for all-optical soliton synchronous regeneration. Simulations show substantial improvement in transmission in this device compared with single-control devices, owing to chirp-free modulation. The absence of chirp is confirmed experimentally through a spectral analysis of the dual-control modulator.

  19. Utilizing nonlinear optical microscopy to investigate the development of early cancer in nude mice in vivo

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Chin; Li, Feng-Chieh; Lin, Sung-Jan; Lo, Wen; Dong, Chen-Yuan

    2007-07-01

    In this investigation, we used in vivo nonlinear optical microscopy to image normal and carcinogen DMBA treated skin tissues of nude mice. We acquired two-photon autofluroescence and second harmonic generation (SHG) images of the skin tissue, and applied the ASI (Autofluorescence versus SHG Index) to the resulting image. This allows us to visualize and quantify the interaction between mouse skin cells and the surrounding connective tissue. We found that as the imaging depth increases, ASI has a different distribution in the normal and the treated skin tissues. Since the DMBA treated skin eventually became squamous cell carcinoma (SCC), our results show that the physiological changes to mouse skin en route to become cancer can be effectively tracked by multiphoton microscopy. We envision this approach to be effective in studying tumor biology and tumor treatment procedures.

  20. Broadband Supercontinuum Spectrum Generated Highly Nonlinear Photonic Crystal Fiber Applicable to Medical and Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Begum, Feroza; Namihira, Yoshinori; Kaijage, Shubi F.; Kinjo, Tatsuya

    2011-09-01

    Optical-fiber-based supercontinuum (SC) light sources have attracted much research attention in recent years. High-quality nonlinear optical fibers allow us to readily implement stable and practical SC sources. In this work, we present a highly nonlinear photonic crystal fiber (HN-PCF) in optical coherence tomography (OCT) and telecommunication windows that can generate SC spectra. The finite difference method with an anisotropic perfectly matched layer boundary condition is used to calculate different properties of the proposed HN-PCF. From numerical simulation results, it is found that the HN-PCF nonlinear coefficients are more than 108.0, 74.0, and 53.0 (W·km)-1 at 1.06, 1.31, and 1.55 µm, respectively. The flattened chromatic dispersion is 0 to -4.0 ps/(nm·km) in the wavelength range of 1.06 to 1.7 µm (640 nm bandwidth), and the confinement loss is lower than 10-2 dB/km in the entire wavelength range. The generated supercontinuum bandwidths are 295.0, 408.0, and 590.0 nm at 1.06, 1.31, and 1.55 µm, respectively. The calculated longitudinal resolutions for biomedical imaging are 1.2, 1.2, and 1.1 µm at 1.06, 1.31, and 1.55 µm, respectively.

  1. All-optical devices based on carrier nonlinearities for optical filtering and spectral equalization

    NASA Astrophysics Data System (ADS)

    Burger, Johan Petrus

    InGaAsP-based quantum wells can display nonlinear refractive index changes of ~0.1 near the band-edge for intrawell carrier density changes of 1 × 1018cm-3, due to effects like bandfilling and the plasma effect, which make these materials promising for the realization of all-optical signal processing devices, as demonstrated here. A novel single passband filter with sub-gigahertz bandwidth and greater than 40nm of tunability was experimentally demonstrated. The filter uses the detuning characteristics of nearly degenerate four-wave mixing in a broad area semiconductor optical amplifier to obtain frequency selectivity. The key to this demonstration was the spatial separation of the filtered signal from the input signal, based on their different propagation directions. An analysis of an analogous integrated optic dual-order mode nonlinear mode-converter, with integrated mode sorters which separate the signal from the interacting modes, was also undertaken. This device is promising as a filter, a wavelength converter, notch filter, and a wavelength recognizing switch. Novel ways to prevent carrier diffusion, which washes out the nonlinear grating, were suggested. It is important to have a large mutual overlap to modal overlap ratio of the two interacting modes on the nonlinear medium, because the mixing efficiency scales as the fourth power of this number. Three types of integrated optic limiters (based on Kerr- like nonlinearities) namely an all-optical cutoff modulator, a nonlinear Y-branch and an interferometer with an internal Kerr element, were theoretically investigated. A beam propagation program, which can solve the propagation of an optical field in a semiconductor in the presence of carrier diffusion, was developed for the numerical analysis of these structures. A negative feedback mechanism was identified in the Y-branch devices and a new limiting configuration was discovered in a Y- branch with a selectively placed defocusing nonlinearity. Dichroic

  2. Nonlinear optical response of the collagen triple helix and second harmonic microscopy of collagen liquid crystals

    NASA Astrophysics Data System (ADS)

    Deniset-Besseau, A.; De Sa Peixoto, P.; Duboisset, J.; Loison, C.; Hache, F.; Benichou, E.; Brevet, P.-F.; Mosser, G.; Schanne-Klein, M.-C.

    2010-02-01

    Collagen is characterized by triple helical domains and plays a central role in the formation of fibrillar and microfibrillar networks, basement membranes, as well as other structures of the connective tissue. Remarkably, fibrillar collagen exhibits efficient Second Harmonic Generation (SHG) and SHG microscopy proved to be a sensitive tool to score fibrotic pathologies. However, the nonlinear optical response of fibrillar collagen is not fully characterized yet and quantitative data are required to further process SHG images. We therefore performed Hyper-Rayleigh Scattering (HRS) experiments and measured a second order hyperpolarisability of 1.25 10-27 esu for rat-tail type I collagen. This value is surprisingly large considering that collagen presents no strong harmonophore in its amino-acid sequence. In order to get insight into the physical origin of this nonlinear process, we performed HRS measurements after denaturation of the collagen triple helix and for a collagen-like short model peptide [(Pro-Pro-Gly)10]3. It showed that the collagen large nonlinear response originates in the tight alignment of a large number of weakly efficient harmonophores, presumably the peptide bonds, resulting in a coherent amplification of the nonlinear signal along the triple helix. To illustrate this mechanism, we successfully recorded SHG images in collagen liquid solutions by achieving liquid crystalline ordering of the collagen triple helices.

  3. 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.

  4. Nonlinear optical properties of nitrogen-doped bilayer graphene

    NASA Astrophysics Data System (ADS)

    Anand, Benoy; Podila, Ramakrishna; Rao, Apparao M.; Philip, Reji; Sai, S. Siva Sankara

    2013-06-01

    The electronic properties of graphene can be controlled by substitutional doping to obtain p-type or n-type characteristics. To this end, bilayer graphene films are synthesized using CVD method and substitutionally doped with Nitrogen (N). Previously, XPS measurements done in tandem with Raman spectroscopy revealed that the rich chemistry between carbon and nitrogen can result in pyridinic, pyrrolic, or graphitic configurations. The nonlinear optical properties (NLO) of both pristine and N-doped graphene samples are studied in both nanosecond and femtosecond excitation regimes using open aperture Z-scan method. Similar to the previous observations with Raman spectroscopy, we see that the NLO properties are more sensitive to the local bonding environments which determine the defect density in the graphene lattice, rather than just the dopant percentage. Our results give more insights into the effect of defects on the NLO properties of doped graphene which help in tailor making graphene samples for applications like modelocking and optical switching.

  5. 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.

  6. Growth and nonlinear optical characterization of organic single crystal films

    NASA Astrophysics Data System (ADS)

    Zhou, Ligui

    1997-12-01

    Organic single crystal films are important for various future applications in photonics and integrated optics. The conventional method for inorganic crystal growth is not suitable for organic materials, and the high temperature melting method is not good for most organic materials due to decomposition problems. We developed a new method-modified shear method-to grow large area organic single crystal thin films which have exceptional nonlinear optical properties and high quality surfaces. Several organic materials (NPP, PNP and DAST) were synthesized and purified before the thin film crystal growth. Organic single crystal thin films were grown from saturated organic solutions using modified shear method. The area of single crystal films were about 1.5 cm2 for PNP, 1 cm2 for NPP and 5 mm2 for DAST. The thickness of the thin films which could be controlled by the applied pressure ranged from 1μm to 10 μm. The single crystal thin films of organic materials were characterized by polarized microscopy, x-ray diffraction, polarized UV-Visible and polarized micro-FTIR spectroscopy. Polarized microscopy showed uniform birefringence and complete extinction with the rotation of the single crystal thin films under crossed- polarization, which indicated high quality single crystals with no scattering. The surface orientation of single crystal thin films was characterized by x-ray diffraction. The molecular orientation within the crystal was further studied by the polarized UV-Visible and Polarized micro-FTIR techniques combined with the x-ray and polarized microscopy results. A Nd:YAG laser with 35 picosecond pulses at 1064nm wavelength was employed to perform the nonlinear optical characterization of the organic single crystal thin films. Two measurement techniques were used to study the crystal films: second harmonic generation (SHG) and electro-optic (EO) effect. SHG results showed that the nonlinear optical coefficient of NPP was 18 times that of LiNbO3, a standard

  7. 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.

  8. Dimensionality of InGaAs nonlinear optical response

    SciTech Connect

    Bolton, S.R. |

    1995-07-01

    In this thesis the ultrafast optical properties of a series of InGaAs samples ranging from the two to the three dimensional limit are discussed. An optical system producing 150 fs continuum centered at 1.5 microns was built. Using this system, ultrafast pump-probe and four wave mixing experiments were performed. Carrier thermalization measurements reveal that screening of the Coulomb interaction is relatively unaffected by confinement, while Pauli blocking nonlinearities at the band edge are approximately twice as strong in two dimensions as in three. Carrier cooling via phonon emission is influenced by confinement due both to the change in electron distribution function and the reduction in electron phonon coupling. Purely coherent band edge effects, as measured by the AC Stark effect and four wave mixing, are found to be dominated by the changes in excitonic structure which take place with confinement.

  9. Integrin Targeting for Tumor Optical Imaging

    PubMed Central

    Ye, Yunpeng; Chen, Xiaoyuan

    2011-01-01

    Optical imaging has emerged as a powerful modality for studying molecular recognitions and molecular imaging in a noninvasive, sensitive, and real-time way. Some advantages of optical imaging include cost-effectiveness, convenience, and non-ionization safety as well as complementation with other imaging modalities such as positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). Over the past decade, considerable advances have been made in tumor optical imaging by targeting integrin receptors in preclinical studies. This review has emphasized the construction and evaluation of diverse integrin targeting agents for optical imaging of tumors in mouse models. They mainly include some near-infrared fluorescent dye-RGD peptide conjugates, their multivalent analogs, and nanoparticle conjugates for targeting integrin αvβ3. Some compounds targeting other integrin subtypes such as α4β1 and α3 for tumor optical imaging have also been included. Both in vitro and in vivo studies have revealed some promising integrin-targeting optical agents which have further enhanced our understanding of integrin expression and targeting in cancer biology as well as related anticancer drug discovery. Especially, some integrin-targeted multifunctional optical agents including nanoparticle-based optical agents can multiplex optical imaging with other imaging modalities and targeted therapy, serving as an attractive type of theranostics for simultaneous imaging and targeted therapy. Continued efforts to discover and develop novel, innovative integrin-based optical agents with improved targeting specificity and imaging sensitivity hold great promises for improving cancer early detection, diagnosis, and targeted therapy in clinic. PMID:21546996

  10. Gated frequency-resolved optical imaging with an optical parametric amplifier for medical applications

    SciTech Connect

    Cameron, S.M.; Bliss, D.E.

    1997-02-01

    Implementation of optical imagery in a diffuse inhomogeneous medium such as biological tissue requires an understanding of photon migration and multiple scattering processes which act to randomize pathlength and degrade image quality. The nature of transmitted light from soft tissue ranges from the quasi-coherent properties of the minimally scattered component to the random incoherent light of the diffuse component. Recent experimental approaches have emphasized dynamic path-sensitive imaging measurements with either ultrashort laser pulses (ballistic photons) or amplitude modulated laser light launched into tissue (photon density waves) to increase image resolution and transmissive penetration depth. Ballistic imaging seeks to compensate for these {open_quotes}fog-like{close_quotes} effects by temporally isolating the weak early-arriving image-bearing component from the diffusely scattered background using a subpicosecond optical gate superimposed on the transmitted photon time-of-flight distribution. The authors have developed a broadly wavelength tunable (470 nm -2.4 {mu}m), ultrashort amplifying optical gate for transillumination spectral imaging based on optical parametric amplification in a nonlinear crystal. The time-gated image amplification process exhibits low noise and high sensitivity, with gains greater than 104 achievable for low light levels. We report preliminary benchmark experiments in which this system was used to reconstruct, spectrally upcovert, and enhance near-infrared two-dimensional images with feature sizes of 65 {mu}m/mm{sup 2} in background optical attenuations exceeding 10{sup 12}. Phase images of test objects exhibiting both absorptive contrast and diffuse scatter were acquired using a self-referencing Shack-Hartmann wavefront sensor in combination with short-pulse quasi-ballistic gating. The sensor employed a lenslet array based on binary optics technology and was sensitive to optical path distortions approaching {lambda}/100.

  11. All-optical UWB signal generation and multicasting using a nonlinear optical loop mirror.

    PubMed

    Huang, Tianye; Li, Jia; Sun, Junqiang; Chen, Lawrence R

    2011-08-15

    An all-optical scheme for ultra-wideband (UWB) signal generation (positive and negative monocycle and doublet pulses) and multicasting using a nonlinear optical loop mirror (NOLM) is proposed and demonstrated. Five UWB signals (1 monocycle and 4 doublet pulses) are generated simultaneously from a single Gaussian optical pulse. The fractional bandwidths of the monocycle pulses are approximately 100% while those of the doublet pulses range from 100% to 133%. The UWB signals are then modulated using a 2(15)-1 pseudorandom bit sequence (PRBS) and error-free performance for each multicast channel is obtained. PMID:21934951

  12. All-optical UWB signal generation and multicasting using a nonlinear optical loop mirror

    NASA Astrophysics Data System (ADS)

    Huang, Tianye; Li, Jia; Sun, Junqiang; Chen, Lawrence R.

    2011-08-01

    An all-optical scheme for ultra-wideband (UWB) signal generation (positive and negative monocycle and doublet pulses) and multicasting using a nonlinear optical loop mirror (NOLM) is proposed and demonstrated. Five UWB signals (1 monocycle and 4 doublet pulses) are generated simultaneously from a single Gaussian optical pulse. The fractional bandwidths of the monocycle pulses are approximately 100% while those of the doublet pulses range from 100% to 133%. The UWB signals are then modulated using a 215 - 1 pseudorandom bit sequence (PRBS) and error-free performance for each multicast channel is obtained.

  13. Structural elucidation, optical, magnetic and nonlinear optical properties of oxystyryl dyes.

    PubMed

    Koleva, Bojidarka B; Stoyanov, Stanimir; Kolev, Tsonko; Petkov, Ivan; Spiteller, Michael

    2009-01-01

    Structure, magnetic and optical properties of tetraphenylborate salts of 2,5-[1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]piridinium]-propane and butane are performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC tandem ESI mess spectrometry (MS/MS), (1)H, (13)C and (1)H-(1)H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are used for performing of the structures, optical and nonlinear optical properties of the studied compounds. PMID:18722806

  14. Structural elucidation, optical, magnetic and nonlinear optical properties of oxystyryl dyes

    NASA Astrophysics Data System (ADS)

    Koleva, Bojidarka B.; Stoyanov, Stanimir; Kolev, Tsonko; Petkov, Ivan; Spiteller, Michael

    2009-01-01

    Structure, magnetic and optical properties of tetraphenylborate salts of 2,5-[1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]piridinium]-propane and butane are performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC tandem ESI mess spectrometry (MS/MS), 1H, 13C and 1H- 1H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are used for performing of the structures, optical and nonlinear optical properties of the studied compounds.

  15. All-optical logic devices with cascaded nonlinear couplers.

    PubMed

    Wang, Y; Wang, Z H; Bialkowski, M E

    2000-08-10

    The switching behaviors of cascaded nonlinear couplers were investigated. They have nearly ideal digital-switching characteristics, and their output power levels can be adjusted by means of varying the nonlinear coupling coefficient of the final coupler. The two-input excitation nonlinear cascaded couplers can perform not only switching operations but also a series of logic operations. The logic operations depend mainly on the coupling length of the two-input coupler and its initial inputs. The power corresponding to the rising and falling ridge of the logic operating waveforms can be shifted effectively by means of varying the switching power of the reshaper. Allowable ranges of three important parameters--coupling length of the two-input coupler L(1), bias optical power P(bia), and phase difference psi between the signal and bias beams for six fundamental logic operations--were calculated. Curves for design considerations and suggestions for the best choice of parameters for stable and reliable logic operations and, or, xor, nand, nor, and nxor are also presented individually. PMID:18349996

  16. Low power continuous wave laser induced optical nonlinearities in saffron ( Crocus Sativus L.)

    NASA Astrophysics Data System (ADS)

    Nasibov, H.; Mamedbeili, I.

    2010-12-01

    We report on the low power CW laser induced nonlinear optical responses of Saffron (stigmata of Crocus Savitus L.) ethanol and methanol extracts. The optical nonlinearities were investigated by performing Z-scan measurements at 470 and 535 nm wavelengths. At both wavelengths the material has a strong nonlinear refraction, mainly of thermal origin. However, only at 470 nm wavelength the material exhibit pronounced saturable nonlinear absorption. Long-term (70 days) stability measurements indicated that the nonlinearities in the Saffron extracts are due to their nonvolatile components. This study shows that there is great potential for Saffron extracts to be used in nonlinear photonic applications.

  17. Magnetic resonance imaging of radiation optic neuropathy

    SciTech Connect

    Zimmerman, C.F.; Schatz, N.J.; Glaser, J.S. )

    1990-10-15

    Three patients with delayed radiation optic neuropathy after radiation therapy for parasellar neoplasms underwent magnetic resonance imaging. The affected optic nerves and chiasms showed enlargement and focal gadopentetate dimeglumine enhancement. The magnetic resonance imaging technique effectively detected and defined anterior visual pathway changes of radionecrosis and excluded the clinical possibility of visual loss because of tumor recurrence.

  18. Nonlinear Optics with Tapered Fibers and Magneto-Optically Trapped Rubidium

    NASA Astrophysics Data System (ADS)

    Little, Bethany; Mullarkey, Chris; Howell, John; Vamivakas, Nick; Lin, Qiang

    2016-05-01

    Tapered optical fibers of sub-wavelength diameter present a promising means of integrating the light-atom interaction into larger scale devices. We present work on a tapered fiber system loaded by a magneto optical trap of Rubidium atoms, in which a combination of red and blue detuned beams create a one-dimensional lattice trap along the fiber. The same fiber is used for interacting with the atoms in the trap via the evanescent fields of light propagating along the fiber. Light storage has been demonstrated in a similar system with Cesium, and we believe that much nonlinear optics remains to be explored in this regime. We also plan to see how these nonlinear effects can be enhanced with the addition of a micro-resonator such as the ones in.

  19. Remoted all optical instantaneous frequency measurement system using nonlinear mixing in highly nonlinear optical fiber.

    PubMed

    Bui, Lam Anh; Mitchell, Arnan

    2013-04-01

    A novel remoted instantaneous frequency measurement system using all optical mixing is demonstrated. This system copies an input intensity modulated optical carrier using four wave mixing, delays this copy and then mixes it with the original signal, to produce an output idler tone. The intensity of this output can be used to determine the RF frequency of the input signal. This system is inherently broadband and can be easily scaled beyond 40 GHz while maintaining a DC output which greatly simplifies receiving electronics. The remoted configuration isolates the sensitive and expensive receiver hardware from the signal sources and importantly allows the system to be added to existing microwave photonic implementations without modification of the transmission module. PMID:23571944

  20. Functional Nonlinear Mixed Effects Models For Longitudinal Image Data

    PubMed Central

    Luo, Xinchao; Zhu, Lixing; Kong, Linglong; Zhu, Hongtu

    2015-01-01

    Motivated by studying large-scale longitudinal image data, we propose a novel functional nonlinear mixed effects modeling (FN-MEM) framework to model the nonlinear spatial-temporal growth patterns of brain structure and function and their association with covariates of interest (e.g., time or diagnostic status). Our FNMEM explicitly quantifies a random nonlinear association map of individual trajectories. We develop an efficient estimation method to estimate the nonlinear growth function and the covariance operator of the spatial-temporal process. We propose a global test and a simultaneous confidence band for some specific growth patterns. We conduct Monte Carlo simulation to examine the finite-sample performance of the proposed procedures. We apply FNMEM to investigate the spatial-temporal dynamics of white-matter fiber skeletons in a national database for autism research. Our FNMEM may provide a valuable tool for charting the developmental trajectories of various neuropsychiatric and neurodegenerative disorders. PMID:26213453

  1. Organic non-linear optics and opto-electronics

    NASA Astrophysics Data System (ADS)

    Maldonado, J. L.; Ramos-Ortíz, G.; Rodríguez, M.; Meneses-Nava, M. A.; Barbosa-García, O.; Santillán, R.; Farfán, N.

    2010-12-01

    π-conjugated organic molecules and polymers are of great importance in physics, chemistry, material science and engineering. It is expected that, in the near future, organic materials will find widespread use in many technological applications. In the case of organic opto-electronic systems, the list of devices includes light emitting diodes (OLEDs), photovoltaic cells (OPVs), field-effect transistors (OFET), photorefractive materials for light manipulation, among others. These materials are also used for photonic applications: all-optical switching, modulators, optical correlators, plastic waveguides, all polymeric integrated circuits, solid-state lasers, and for biophotonic applications as in the case of the development of organic labels for multiphoton microscopy and photodynamic therapy. The advances in the developing of organic compounds with better mechanical, electrical, and optical (linear and non-linear) characteristics are of a great importance for this field. Here, we present the research on this area carried out at the Centro de Investigaciones en Óp-tica (CIO), in collaboration with Chemistry Departments of different institutions. This work focuses on the optical characterization of materials through several techniques such as TOF, FWM, TBC, THG Maker Fringes, HRS, Z-scan, and TPEF. Additionally, some applications, such as dynamic holography by using photorefractive polymers, and OPVs cells will be discussed.

  2. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  3. Tuning nonlinear optical absorption properties of WS₂ nanosheets.

    PubMed

    Long, Hui; Tao, Lili; Tang, Chun Yin; Zhou, Bo; Zhao, Yuda; Zeng, Longhui; Yu, Siu Fung; Lau, Shu Ping; Chai, Yang; Tsang, Yuen Hong

    2015-11-14

    To control the optical properties of two-dimensional (2D) materials is a long-standing goal, being of both fundamental and technological significance. Tuning nonlinear optical absorption (NOA) properties of 2D transition metal dichalcogenides in a cost effective way has emerged as an important research topic because of its possibility to custom design NOA properties, implying enormous applications including optical computers, communications, bioimaging, and so on. In this study, WS2 with different size and thickness distributions was fabricated. The results demonstrate that both NOA onset threshold, F(ON), and optical limiting threshold, F(OL), of WS2 under the excitation of a nanosecond pulsed laser can be tuned over a wide range by controlling its size and thickness. The F(ON) and F(OL) show a rapid decline with the decrease of size and thickness. Due to the edge and quantum confinement effect, WS2 quantum dots (2.35 nm) exhibit the lowest F(ON) (0.01 J cm(-2)) and F(OL) (0.062 J cm(-2)) among all the samples, which are comparable to the lowest threshold achieved in graphene based materials, showing great potential as NOA materials with tunable properties. PMID:26456545

  4. Reflective optical imaging system with balanced distortion

    SciTech Connect

    Chapman, H.N.; Hudyma, R.M.; Shafer, D.R.; Sweeney, D.W.

    1999-10-26

    An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate is disclosed. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  5. Reflective optical imaging systems with balanced distortion

    DOEpatents

    Hudyma, Russell M.

    2001-01-01

    Optical systems compatible with extreme ultraviolet radiation comprising four reflective elements for projecting a mask image onto a substrate are described. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical systems are particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput, and allows higher semiconductor device density. The inventive optical systems are characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  6. Nonlinear optical properties of organic materials: A theoretical study

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.

    1991-01-01

    Replacement of electronic switching circuits in computing and telecommunication systems with purely optical devices offers the potential for extremely high throughput and compact information processing systems. The potential application of organic materials containing molecules with large nonresonant nonlinear effects in this area have triggered intensive research during the last decade. Interest on this area was due to two facts: (1) that many organic materials show nonlinearities that are orders of magnitude larger than those of conventional inorganic materials such as lithium niobate and potassium dihydrogen phosphate; and (2) that organic materials show much flexibility in terms of molecular designs. Some of the desirable characteristics that these materials should have are that they be transparent to the frequency of the incident laser and its second or third harmonic, that they have a high damage threshold, and, in the case of second-order effects, that their crystal structure or molecular orientation be accentric. Since polymeric assemblages can enhance the nonlinear response of organic molecules severalfold, efforts have been directed toward the synthesis of thin films with interpenetrating lattices of electroactive molecules. The goal of this theoretical investigation is to predict the magnitude of the molecular polarizabilities of organic molecules that could be incorporated into films. These calculations are intended to become a powerful tool to assist material scientists in screening for the best candidates for optical applications. The procedure that was developed for the present calculations is based on the static-field approach, and is a modification to the method developed by Dewar and Stewart, 1984 for calculating molecular linear polarizabilities.

  7. Image enhancement by nonlinear extrapolation in frequency space

    NASA Astrophysics Data System (ADS)

    Greenspan, Hayit; Anderson, Charles H.

    1994-03-01

    A procedure for creating images with higher resolution than the sampling rate would allow is described. The enhancement algorithm augments the frequency content of the image using shape-invariant properties of edges across scale by using a non-linearity that generates phase- coherent higher harmonics. The procedure utilizes the Laplacian pyramid image representation. Results are presented depicting the power-spectra augmentation and the visual enhancement of several images. Simplicity of computations and ease of implementation allow for real-time applications such as high-definition television.

  8. Nonlinear optical signal processing for high-speed, spectrally efficient fiber optic systems and networks

    NASA Astrophysics Data System (ADS)

    Zhang, Bo

    The past decade has witnessed astounding boom in telecommunication network traffic. With the emergence of multimedia over Internet, the high-capacity optical transport systems have started to shift focus from the core network towards the end users. This trend leads to diverse optical networks with transparency and reconfigurability requirement. As single channel data rate continues to increase and channel spacing continues to shrink for high capacity, high spectral efficiency, the workload on conventional electronic signal processing elements in the router nodes continues to build up. Performing signal processing functions in the optical domain can potentially alleviate the speed bottleneck if the unique optical properties are efficiently leveraged to assist electronic processing methodologies. Ultra-high bandwidth capability along with the promise for multi-channel and format-transparent operation make optical signal processing an attractive technology which is expected to have great impact on future optical networks. For optical signal processing applications in fiber-optic network and systems, a laudable goal would be to explore the unique nonlinear optical processes in novel photonic devices. This dissertation investigates novel optical signal processing techniques through simulations and experimental demonstrations, analyzes limitations of these nonlinear processing elements and proposes techniques to enhance the system performance or designs for functional photonic modules. Two key signal-processing building blocks for future optical networks, namely slow-light-based tunable optical delay lines and SOA-based high-speed wavelength converters, are presented in the first part of the dissertation. Phase preserving and spectrally efficient slow light are experimentally demonstrated using advanced modulation formats. Functional and novel photonic modules, such as multi-channel synchronizer and variable-bit-rate optical time division multiplexer are designed and

  9. Differential Polarization Nonlinear Optical Microscopy with Adaptive Optics Controlled Multiplexed Beams

    PubMed Central

    Samim, Masood; Sandkuijl, Daaf; Tretyakov, Ian; Cisek, Richard; Barzda, Virginijus

    2013-01-01

    Differential polarization nonlinear optical microscopy has the potential to become an indispensable tool for structural investigations of ordered biological assemblies and microcrystalline aggregates. Their microscopic organization can be probed through fast and sensitive measurements of nonlinear optical signal anisotropy, which can be achieved with microscopic spatial resolution by using time-multiplexed pulsed laser beams with perpendicular polarization orientations and photon-counting detection electronics for signal demultiplexing. In addition, deformable membrane mirrors can be used to correct for optical aberrations in the microscope and simultaneously optimize beam overlap using a genetic algorithm. The beam overlap can be achieved with better accuracy than diffraction limited point-spread function, which allows to perform polarization-resolved measurements on the pixel-by-pixel basis. We describe a newly developed differential polarization microscope and present applications of the differential microscopy technique for structural studies of collagen and cellulose. Both, second harmonic generation, and fluorescence-detected nonlinear absorption anisotropy are used in these investigations. It is shown that the orientation and structural properties of the fibers in biological tissue can be deduced and that the orientation of fluorescent molecules (Congo Red), which label the fibers, can be determined. Differential polarization microscopy sidesteps common issues such as photobleaching and sample movement. Due to tens of megahertz alternating polarization of excitation pulses fast data acquisition can be conveniently applied to measure changes in the nonlinear signal anisotropy in dynamically changing in vivo structures. PMID:24022688

  10. A new method of assessing the surgical margin in rectal carcinoma—using nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Li, Lianhuang; Chen, Zhifen; Kang, Deyong; Deng, Tongxin; Jiang, Liwei; Zhou, Yi; Liu, Xing; Jiang, Weizhong; Zhuo, Shuangmu; Guan, Guoxian; Chi, Pan; Chen, Jianxin

    2016-06-01

    Nowadays, surgical resection is still the most effective treatment strategy for rectal carcinoma and one of the most important factors affecting whether the operation is successful or not is the surgical margin determination, especially in the distal rectal carcinoma which should take the sphincter-preserving issue into consideration. However, until recently no reliable evaluation method has been developed for this purpose. There are some shortcomings in intraoperative negative surgical margin assessment such as either lack of enough detailed information of biological tissues or the fact that it is time-consuming. Multiphoton microscopy (MPM)—nonlinear optical microscopy, which is based on the nonlinear optical process two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), has the ability to label freely and noninvasively visualize tissue micro-architecture at the sub-cellular level. The advantage of providing high contrast and high resolution biomedical image in real time makes MPM have a wide range of applications in life sciences. In this study, we introduced MPM to identify the boundary between normal and abnormal rectal tissues. MPM images clearly exhibit biological tissue microstructure and its morphological changes in the regions of our interest, which enable it to determine the surgical margin in rectal carcinoma. It can be foreseen that once MPM imaging system is used in clinical examination, it will greatly improve the accuracy of surgical resection.

  11. Multi-crack imaging using nonclassical nonlinear acoustic method

    NASA Astrophysics Data System (ADS)

    Zhang, Lue; Zhang, Ying; Liu, Xiao-Zhou; Gong, Xiu-Fen

    2014-10-01

    Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure.

  12. Dual-frequency transducer for nonlinear contrast agent imaging.

    PubMed

    Guiroy, Axel; Novell, Anthony; Ringgaard, Erling; Lou-Moeller, Rasmus; Grégoire, Jean-Marc; Abellard, André-Pierre; Zawada, Tomasz; Bouakaz, Ayache; Levassort, Franck

    2013-12-01

    Detection of high-order nonlinear components issued from microbubbles has emerged as a sensitive method for contrast agent imaging. Nevertheless, the detection of these high-frequency components, including the third, fourth, and fifth harmonics, remains challenging because of the lack of transducer sensitivity and bandwidth. In this context, we propose a new design of imaging transducer based on a simple fabrication process for high-frequency nonlinear imaging. The transducer is composed of two elements: the outer low-frequency (LF) element was centered at 4 MHz and used in transmit mode, whereas the inner high-frequency (HF) element centered at 14 MHz was used in receive mode. The center element was pad-printed using a lead zirconate titanate (PZT) paste. The outer element was molded using a commercial PZT, and curved porous unpoled PZT was used as backing. Each piezoelectric element was characterized to determine the electromechanical performance with thickness coupling factor around 45%. After the assembly of the two transducer elements, hydrophone measurements (electroacoustic responses and radiation patterns) were carried out and demonstrated a large bandwidth (70% at -3 dB) of the HF transducer. Finally, the transducer was evaluated for contrast agent imaging using contrast agent microbubbles. The results showed that harmonic components (up to the sixth harmonic) of the microbubbles were successfully detected. Moreover, images from a flow phantom were acquired and demonstrated the potential of the transducer for high-frequency nonlinear contrast imaging. PMID:24297028

  13. A study on linear and non-linear optical constants of Rhodamine B thin film deposited on FTO glass

    NASA Astrophysics Data System (ADS)

    Yahia, I. S.; Jilani, Asim; Abutalib, M. M.; AlFaify, S.; Shkir, M.; Abdel-wahab, M. Sh.; Al-Ghamdi, Attieh A.; El-Naggar, A. M.

    2016-06-01

    The aim of this research was to fabricate/deposit the good quality thin film of Rhodamine B dye on fluorine doped tin oxide glass substrate by the low cost spin coating technique and study their linear and nonlinear optical parameters. The thickness of the thin film was measured about 300 nm with alpha step system. The transmittance of the fabricated thin film was found to be above 75% corresponding to the fluorine doped tin oxide layer. The structural analysis was performed with X-rays diffraction spectroscopy. Atomic force microscope showed the topographic image of deposited thin film. Linear optical constant like absorption coefficient, band gap, and extinction index was calculated. The dielectric constant was calculated to know the optical response of Rhodamine B dye over fluorine doped tin oxide substrate. The nonlinear optical constant like linear optical susceptibility χ(1), nonlinear optical susceptibility χ(3), nonlinear refractive index (n2) were calculated by spectroscopic method. This method has advantage over the experimental method like Z-Scan for organic dye base semiconductors for future advance optoelectronics applications like dye synthesis solar cell.

  14. Nonlocal nonlinear optical response of graphene oxide-Au nanoparticles dispersed in different solvents

    NASA Astrophysics Data System (ADS)

    Fakhri, P.; Rashidian Vaziri, M. R.; Jaleh, B.; Partovi Shabestari, N.

    2016-01-01

    In this paper, we report on the preparation of graphene oxide and graphene oxide-Au nanodispersions in various solvents, such as water, DMF (N,N-dimethylformamide) and NMP (N-methyl-2-pyrrolidone). Optical, structural and nonlinear optical properties of all the samples have been studied. The nonlinear optical properties have been measured using the z-scan technique. It is shown that the incorporation of Au nanoparticles can greatly improve the nonlinear optical properties of graphene oxide. More importantly, the fact is recognized that the media that surround the nonlinear sample can influence its nonlinear optical properties by their nonlocal action. The nonlocal z-scan theory has been used to estimate the role of the surrounding medium in changing the samples’ nonlinear responses.

  15. Testing of electro-optical imaging systems

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Krzysztof; Barela, Jaroslaw; Firmanty, Krzysztof

    2004-08-01

    Humans cannot objectively judge electro-optical imaging systems looking on an image of typical scenery. Quality of the image can be bad for some people but good for others and therefore objective test methods and advanced equipment are needed to evaluate these imaging systems. Test methods and measuring systems that enable reliable testing and evaluation of modern thermal cameras, color and monochrome TV cameras, LLLTV cameras and image intensifier systems are presented in this paper.

  16. Third order optical nonlinearity and optical limiting studies of propane hydrazides

    NASA Astrophysics Data System (ADS)

    Naseema, K.; Manjunatha, K. B.; Sujith, K. V.; Umesh, G.; Kalluraya, Balakrishna; Rao, Vijayalakshmi

    2012-09-01

    Four hydrazones, 2-(4-isobutylphenyl)-N'-[phenylmethylene] propanehydrazide (P1), 2-(4-isobutylphenyl)-N'-[(4- tolyl)methylene] propane hydrazide (P2), 2-(4-isobutylphenyl)-N'-[1-(4- chlorophenyl)ethylidene] propanehydrazide (P3) and 2-(4-isobutylphenyl)-N'-[1-(4-Nitrrophenyl)ethylidene] propane hydrazide (P4) were synthesized and their third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. The measurement on the compound-P1 is not reported as there is no detectable nonlinear response. Open aperture data of the other three compounds indicate two photon absorption at this wavelength. The nonlinear refractive index n2, nonlinear absorption coefficient β, magnitude of effective third order susceptibility χ(3), the second order hyperpolarizability γh and the coupling factor ρ have been estimated. The values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylideneacetone derivatives. The experimentally determined values of β, n2, Re χ(3) and Im χ(3), γh and ρ of the compound-P4 are 1.42 cm/GW, -0.619 × 10-11 esu, -0.663 × 10-13 esu, 0.22 × 10-13 esu, 0.34 × 10-32 esu and 0.33 respectively. Further the compound-P4 exhibited the best optical power limiting behavior at 532 nm among the compounds studied. Our studies suggest that compounds P2, P3 and P4 are potential candidates for the optical device applications such as optical limiters and optical switches.

  17. Piecewise nonlinear image registration using DCT basis functions

    NASA Astrophysics Data System (ADS)

    Gan, Lin; Agam, Gady

    2015-03-01

    The deformation field in nonlinear image registration is usually modeled by a global model. Such models are often faced with the problem that a locally complex deformation cannot be accurately modeled by simply increasing degrees of freedom (DOF). In addition, highly complex models require additional regularization which is usually ineffective when applied globally. Registering locally corresponding regions addresses this problem in a divide and conquer strategy. In this paper we propose a piecewise image registration approach using Discrete Cosine Transform (DCT) basis functions for a nonlinear model. The contributions of this paper are three-folds. First, we develop a multi-level piecewise registration framework that extends the concept of piecewise linear registration and works with any nonlinear deformation model. This framework is then applied to nonlinear DCT registration. Second, we show how adaptive model complexity and regularization could be applied for local piece registration, thus accounting for higher variability. Third, we show how the proposed piecewise DCT can overcome the fundamental problem of a large curvature matrix inversion in global DCT when using high degrees of freedoms. The proposed approach can be viewed as an extension of global DCT registration where the overall model complexity is increased while achieving effective local regularization. Experimental evaluation results provide comparison of the proposed approach to piecewise linear registration using an affine transformation model and a global nonlinear registration using DCT model. Preliminary results show that the proposed approach achieves improved performance.

  18. A novel method measuring optical fiber nonlinear coefficient based on XPM

    NASA Astrophysics Data System (ADS)

    Zhang, Shuangxi; Wu, Xuqiang; Ai, Fei; Zhang, Chengmei; Zhang, Bo; Yu, Benli

    2009-11-01

    In optic communication systems, the nonlinear effect of the optical fiber is of great importance. There are several methods measuring optical fiber nonlinear coefficient. A novel method measuring optical fiber nonlinear coefficient is proposed, which is based on a Mach-Zehnder interferometer fabricated with 3×3 coupler, polarization controller and so on. According to cross phase modulation (XPM), when two optical waves are injected into the same optical fiber, the phase of one optical wave will be changed because of the other one. So a sinusoidal phase signal will be generated through coupling a sinusoidal modulated high-power laser into one arm of the interferometer, and then the three outputs of the interferometer will contain the sinusoidal phase signal. According to the characteristic of the 3×3 coupler, the phase difference between the three outputs is 2π / 3 . Through mathematics disposition of the three outputs of the interferometer, a couple of orthogonal signals can be yielded. Then the amplitude of the sinusoidal phase signal can be demodulated accurately by arctan method. The length of the optical fiber and the power of the laser can be measured easily, according to expression about the nonlinear phase shift induced by XPM, the optical fiber nonlinear coefficient of certain wavelength will be calculated. The optical fiber nonlinear effect is simulated by the software optisystem, and the process measuring the optical fiber nonlinear coefficient is analyzed in detail based on the schematic design.

  19. Optical Molecular Imaging in the Gastrointestinal Tract

    PubMed Central

    Carns, Jennifer; Keahey, Pelham; Quang, Timothy; Anandasabapathy, Sharmila; Richards-Kortum, Rebecca

    2013-01-01

    Recent developments in optical molecular imaging allow for real-time identification of morphological and biochemical changes in tissue associated with gastrointestinal neoplasia. This review summarizes widefield and high resolution imaging modalities currently in pre-clinical and clinical evaluation for the detection of colorectal cancer and esophageal cancer. Widefield techniques discussed include high definition white light endoscopy, narrow band imaging, autofluoresence imaging, and chromoendoscopy; high resolution techniques discussed include probe-based confocal laser endomicroscopy, high-resolution microendoscopy, and optical coherence tomography. Finally, new approaches to enhance image contrast using vital dyes and molecular-specific targeted contrast agents are evaluated. PMID:23735112

  20. Cold atom dynamics in linear and nonlinear optical potentials

    NASA Astrophysics Data System (ADS)

    Williams, William

    This dissertation has two major components. The first is theoretical work on using multiple optical fields to control atoms. Theoretical models for creating complex optical potentials for use in atomic lithography are explored and a proposal for serial writing of an atomic beam is presented. A proposal to compress a cloud of cold atoms to create a tightly confined cigar shaped cloud of dense atoms for use in atom optics experiments and quantum control is also presented. The second component focuses on the study of nonlinear self-focusing in cold Cesium atoms. Modulation instability is explored in a cold atom environment which produces novel effects such as red detuned modulational instability. Several experimental setups are explored and compared with theoretical models. The first is two-wave mixing which consists of a strong pump beam and a weak probe beam crossing in a MOT. The second is using a counter-propagating pump beam to balance the radiation force of the forward propagating pump beam. The third is retro-reflecting both the probe and the pump beam which creates a more complicated experimental setup with multiple atomic gratings. Energy transfer from the pump to the probe beam via atomic density redistribution for red detuning is presented.