570 Works

Real-time complex temporal response measurements of ultrahigh-speed optical modulators

Yongwoo Park, Tae-Jung Ann & José Azaña
We demonstrate a technique for direct, real-time characterization of the complex (amplitude and phase) temporal response of ultrahigh-speed (GHz-bandwidth) optical modulators. The demonstrated technique is based on pulse interferometry combined with time-frequency mapping processes using fiber linear dispersion. A new mechanism is incorporated to overcome the temporal resolution (bandwidth) limitation of the detectable modulation response in our previously reported setup [1]. This mechanism, referred to as ‘common-path temporal image magnification’, lowers the required detection bandwidth...

Real-time complex temporal response measurements of ultrahigh-speed optical modulators

Yongwoo Park, Tae-Jung Ann & José Azaña
We demonstrate a technique for direct, real-time characterization of the complex (amplitude and phase) temporal response of ultrahigh-speed (GHz-bandwidth) optical modulators. The demonstrated technique is based on pulse interferometry combined with time-frequency mapping processes using fiber linear dispersion. A new mechanism is incorporated to overcome the temporal resolution (bandwidth) limitation of the detectable modulation response in our previously reported setup [1]. This mechanism, referred to as ‘common-path temporal image magnification’, lowers the required detection bandwidth...

Noninvasive label-free imaging of microhemodynamics by optical-resolution photoacoustic microscopy

Song Hu, Konstantin Maslov & Lihong V. Wang
In vivo microcirculatory imaging facilitates the fundamental understanding of many major diseases. However, existing techniques generally require invasive procedures or exogenous contrast agents, which perturb the intrinsic physiology of the microcirculation. Here, we report on optical-resolution photoacoustic microscopy (OR-PAM) for noninvasive label-free microcirculatory imaging at cellular levels. For the first time, OR-PAM demonstrates quantification of hemoglobin concentration and oxygenation in single microvessels down to capillaries. Using this technique, we imaged several important yet elusive microhemodynamic...

Noninvasive label-free imaging of microhemodynamics by optical-resolution photoacoustic microscopy

Song Hu, Konstantin Maslov & Lihong V. Wang
In vivo microcirculatory imaging facilitates the fundamental understanding of many major diseases. However, existing techniques generally require invasive procedures or exogenous contrast agents, which perturb the intrinsic physiology of the microcirculation. Here, we report on optical-resolution photoacoustic microscopy (OR-PAM) for noninvasive label-free microcirculatory imaging at cellular levels. For the first time, OR-PAM demonstrates quantification of hemoglobin concentration and oxygenation in single microvessels down to capillaries. Using this technique, we imaged several important yet elusive microhemodynamic...

Real-time liquid-crystal atmosphere turbulence simulator with graphic processing unit

Lifa Hu, Li Xuan, Dayu Li, Zhaoliang Cao, Quanquan Mu, Yonggang Liu, Zenghui Peng & Xinhai Lu
To generate time-evolving atmosphere turbulence in real time, a phase-generating method for our liquid-crystal (LC) atmosphere turbulence simulator (ATS) is derived based on the Fourier series (FS) method. A real matrix expression for generating turbulence phases is given and calculated with a graphic processing unit (GPU), the GeForce 8800 Ultra. A liquid crystal on silicon (LCOS) with 256×256 pixels is used as the turbulence simulator. The total time to generate a turbulence phase is about...

Real-time liquid-crystal atmosphere turbulence simulator with graphic processing unit

Lifa Hu, Li Xuan, Dayu Li, Zhaoliang Cao, Quanquan Mu, Yonggang Liu, Zenghui Peng & Xinhai Lu
To generate time-evolving atmosphere turbulence in real time, a phase-generating method for our liquid-crystal (LC) atmosphere turbulence simulator (ATS) is derived based on the Fourier series (FS) method. A real matrix expression for generating turbulence phases is given and calculated with a graphic processing unit (GPU), the GeForce 8800 Ultra. A liquid crystal on silicon (LCOS) with 256×256 pixels is used as the turbulence simulator. The total time to generate a turbulence phase is about...

Respiratory gating of anatomical optical coherence tomography images of the human airway

Robert A. McLaughlin, Julian J. Armstrong, Sven Becker, Jennifer H. Walsh, Arpit Jain, David R. Hillman, Peter R. Eastwood & David D. Sampson
Anatomical optical coherence tomography (aOCT) is a long-range endoscopic imaging modality capable of quantifying size and shape of the human airway. A challenge to its in vivo application is motion artifact due to respiratory-related movement of the airway walls. This paper represents the first demonstration of respiratory gating of aOCT airway data, and introduces a novel error measure to guide appropriate parameter selection. Results indicate that at least four gates per respiratory cycle should be...

Respiratory gating of anatomical optical coherence tomography images of the human airway

Robert A. McLaughlin, Julian J. Armstrong, Sven Becker, Jennifer H. Walsh, Arpit Jain, David R. Hillman, Peter R. Eastwood & David D. Sampson
Anatomical optical coherence tomography (aOCT) is a long-range endoscopic imaging modality capable of quantifying size and shape of the human airway. A challenge to its in vivo application is motion artifact due to respiratory-related movement of the airway walls. This paper represents the first demonstration of respiratory gating of aOCT airway data, and introduces a novel error measure to guide appropriate parameter selection. Results indicate that at least four gates per respiratory cycle should be...

Programmable ultrashort-pulsed flying images

M. Bock, S. K. Das & R. Grunwald
We report the generation of programmable two-dimensional arrangements of ultrashort-pulsed fringe-less Bessel-like beams of extended depth of focus (referred to as needle beams) without truncating apertures. A sub-20-fs Ti:sapphire laser and a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) of high-fidelity temporal transfer in phase-only operation mode were used in the experiments. Axicon profiles with ultra-small conical angles were approximated by adapted gray scale distributions. It was demonstrated that digitized image information encoded in amplitude-phase maps of...

Optical microassembly platform for constructing reconfigurable microenvironments for biomedical studies

Peter John Rodrigo, Lóránd Kelemen, Darwin Palima, Carlo Amadeo Alonzo, Pál Ormos & Jesper Glückstad
Cellular development is highly influenced by the surrounding microenvironment. We propose user-reconfigurable microenvironments and bio-compatible scaffolds as an approach for understanding cellular development processes. We demonstrate a model platform for constructing versatile microenvironments by fabricating morphologically complex microstructures by two-photon polymerization (2PP) and then assembling these archetypal building blocks into various configurations using multiple, real-time configurable counterpropagating-beam (CB) traps. The demonstrated capacity for handling feature-rich microcomponents may be further developed into a generalized microassembly platform.

Programmable ultrashort-pulsed flying images

M. Bock, S. K. Das & R. Grunwald
We report the generation of programmable two-dimensional arrangements of ultrashort-pulsed fringe-less Bessel-like beams of extended depth of focus (referred to as needle beams) without truncating apertures. A sub-20-fs Ti:sapphire laser and a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) of high-fidelity temporal transfer in phase-only operation mode were used in the experiments. Axicon profiles with ultra-small conical angles were approximated by adapted gray scale distributions. It was demonstrated that digitized image information encoded in amplitude-phase maps of...

Optical microassembly platform for constructing reconfigurable microenvironments for biomedical studies

Peter John Rodrigo, Lóránd Kelemen, Darwin Palima, Carlo Amadeo Alonzo, Pál Ormos & Jesper Glückstad
Cellular development is highly influenced by the surrounding microenvironment. We propose user-reconfigurable microenvironments and bio-compatible scaffolds as an approach for understanding cellular development processes. We demonstrate a model platform for constructing versatile microenvironments by fabricating morphologically complex microstructures by two-photon polymerization (2PP) and then assembling these archetypal building blocks into various configurations using multiple, real-time configurable counterpropagating-beam (CB) traps. The demonstrated capacity for handling feature-rich microcomponents may be further developed into a generalized microassembly platform.

Multiplexed broadband beam steering system utilizing high speed MEMS mirrors

Caleb Knoernschild, Changsoon Kim, Felix P. Lu & Jungsang Kim
We present a beam steering system based on microelectromechanical systems technology that features high speed steering of multiple laser beams over a broad wavelength range. By utilizing high speed micromirrors with a broadband metallic coating, our system has the flexibility to simultaneously incorporate a wide range of wavelengths and multiple beams. We demonstrate reconfiguration of two independent beams at different wavelengths (780 and 635 nm) across a common 5×5 array with 4 μs settling time....

Multiplexed broadband beam steering system utilizing high speed MEMS mirrors

Caleb Knoernschild, Changsoon Kim, Felix P. Lu & Jungsang Kim
We present a beam steering system based on microelectromechanical systems technology that features high speed steering of multiple laser beams over a broad wavelength range. By utilizing high speed micromirrors with a broadband metallic coating, our system has the flexibility to simultaneously incorporate a wide range of wavelengths and multiple beams. We demonstrate reconfiguration of two independent beams at different wavelengths (780 and 635 nm) across a common 5×5 array with 4 μs settling time....

Optical guiding of absorbing nanoclusters in air

Vladlen G. Shvedov, Anton S. Desyatnikov, Andrei V. Rode, Wieslaw Krolikowski & Yuri S. Kivshar
We suggest a novel approach in all-optical trapping employing a photophoretic force for manipulation of absorbing particles in open air. We demonstrate experimentally the robust three-dimensional guiding, over the distances of a few millimeters, of agglomerates of carbon nanoparticles with the size spanned from 100 nm to 10μm, as well as their acceleration up to velocities of 1 cm/sec. We achieve stable positioning and guiding of particles as well as simultaneous trapping of a large...

Optical guiding of absorbing nanoclusters in air

Vladlen G. Shvedov, Anton S. Desyatnikov, Andrei V. Rode, Wieslaw Krolikowski & Yuri S. Kivshar
We suggest a novel approach in all-optical trapping employing a photophoretic force for manipulation of absorbing particles in open air. We demonstrate experimentally the robust three-dimensional guiding, over the distances of a few millimeters, of agglomerates of carbon nanoparticles with the size spanned from 100 nm to 10μm, as well as their acceleration up to velocities of 1 cm/sec. We achieve stable positioning and guiding of particles as well as simultaneous trapping of a large...

Video rate spectral imaging using a coded aperture snapshot spectral imager

Ashwin A. Wagadarikar, Nikos P. Pitsianis, Xiaobai Sun & David J. Brady
We have previously reported on coded aperture snapshot spectral imagers (CASSI) that can capture a full frame spectral image in a snapshot. Here we describe the use of CASSI for spectral imaging of a dynamic scene at video rate. We describe significant advances in the design of the optical system, system calibration procedures and reconstruction method. The new optical system uses a double Amici prism to achieve an in-line, direct view configuration, resulting in a...

Highly dispersive slot waveguides

Lin Zhang, Yang Yue, Yinying Xiao-Li, Raymond G. Beausoleil & Alan E. Willner
We propose a slot-waveguide with high dispersion, in which a slot waveguide is coupled to a strip waveguide. A negative dispersion of up to -181520 ps/nm/km is obtained due to a strong interaction of the slot and strip modes. A flat and large dispersion is achievable by cascading the dispersive slot-waveguides with varied waveguide thickness or width for dispersion compensation and signal processing applications. We show -31300 ps/nm/km dispersion over 147-nm bandwidth with < 1...

Highly dispersive slot waveguides

Lin Zhang, Yang Yue, Yinying Xiao-Li, Raymond G. Beausoleil & Alan E. Willner
We propose a slot-waveguide with high dispersion, in which a slot waveguide is coupled to a strip waveguide. A negative dispersion of up to -181520 ps/nm/km is obtained due to a strong interaction of the slot and strip modes. A flat and large dispersion is achievable by cascading the dispersive slot-waveguides with varied waveguide thickness or width for dispersion compensation and signal processing applications. We show -31300 ps/nm/km dispersion over 147-nm bandwidth with < 1...

Nonlinear pulse compression of picosecond parabolic-like pulses synthesized with a long period fiber grating filter

David Krčmařík, Radan Slavík, Yongwoo Park & José Azaña
We demonstrate high quality pulse compression at high repetition rates by use of spectral broadening of short parabolic-like pulses in a normally-dispersive highly nonlinear fiber (HNLF) followed by linear dispersion compensation with a conventional SMF-28 fiber. The key contribution of this work is on the use of a simple and efficient long-period fiber grating (LPFG) filter for synthesizing the desired parabolic-like pulses from sech2-like input optical pulses; this all-fiber low-loss filter enables reducing significantly the...

Whispering gallery mode carousel – a photonic mechanism for enhanced nanoparticle detection in biosensing

S. Arnold, D. Keng, S. I. Shopova, S. Holler, W. Zurawsky & F. Vollmer
Individual nanoparticles in aqueous solution are observed to be attracted to and orbit within the evanescent sensing ring of a Whispering Gallery Mode micro-sensor with only microwatts of driving power. This Carousel trap, caused by attractive optical gradient forces, interfacial interactions, and the circulating momentum flux, considerably enhances the rate of transport to the sensing region, thereby overcoming limitations posed by diffusion on such small area detectors. Resonance frequency fluctuations, caused by the radial Brownian...

Video rate spectral imaging using a coded aperture snapshot spectral imager

Ashwin A. Wagadarikar, Nikos P. Pitsianis, Xiaobai Sun & David J. Brady
We have previously reported on coded aperture snapshot spectral imagers (CASSI) that can capture a full frame spectral image in a snapshot. Here we describe the use of CASSI for spectral imaging of a dynamic scene at video rate. We describe significant advances in the design of the optical system, system calibration procedures and reconstruction method. The new optical system uses a double Amici prism to achieve an in-line, direct view configuration, resulting in a...

Whispering gallery mode carousel – a photonic mechanism for enhanced nanoparticle detection in biosensing

S. Arnold, D. Keng, S. I. Shopova, S. Holler, W. Zurawsky & F. Vollmer
Individual nanoparticles in aqueous solution are observed to be attracted to and orbit within the evanescent sensing ring of a Whispering Gallery Mode micro-sensor with only microwatts of driving power. This Carousel trap, caused by attractive optical gradient forces, interfacial interactions, and the circulating momentum flux, considerably enhances the rate of transport to the sensing region, thereby overcoming limitations posed by diffusion on such small area detectors. Resonance frequency fluctuations, caused by the radial Brownian...

Nonlinear pulse compression of picosecond parabolic-like pulses synthesized with a long period fiber grating filter

David Krčmařík, Radan Slavík, Yongwoo Park & José Azaña
We demonstrate high quality pulse compression at high repetition rates by use of spectral broadening of short parabolic-like pulses in a normally-dispersive highly nonlinear fiber (HNLF) followed by linear dispersion compensation with a conventional SMF-28 fiber. The key contribution of this work is on the use of a simple and efficient long-period fiber grating (LPFG) filter for synthesizing the desired parabolic-like pulses from sech2-like input optical pulses; this all-fiber low-loss filter enables reducing significantly the...

Multiplexed force measurements on live cells with holographic optical tweezers

Cecile O. Mejean, Andrew W. Schaefer, Eleanor A. Millman, Paul Forscher & Eric R. Dufresne
We describe open-loop and closed-loop multiplexed force measurements using holographic optical tweezers. We quantify the performance of our novel video-based control system in a driven suspension of colloidal particles. We demonstrate our system’s abilities with the measurement of the mechanical coupling between Aplysia bag cell growth cones and beads functionalized with the neuronal cell adhesion molecule, apCAM. We show that cells form linkages which couple beads to the underlying cytoskeleton. These linkages are intermittent, stochastic...

Resource Types

  • Collection
    562
  • Dataset
    8

Publication Year

  • 2009
    570