176 Works

Membrane deformable mirror for adaptive optics: performance limits in visual optics

Enrique J. Fernández & Pablo Artal
The performance of a membrane deformable mirror with 37 electrodes (OKO Technologies) is studied in order to characterize its utility as an adaptive optics element. The control procedure is based on knowledge of the membrane’s response under the action of each isolate electrode, i.e., the influence functions. The analysis of the mathematical techniques to obtain the control matrix gives useful information about the surfaces that are within the device’s range of production, thus predicting the...

Membrane deformable mirror for adaptive optics: performance limits in visual optics

Enrique J. Fernández & Pablo Artal
The performance of a membrane deformable mirror with 37 electrodes (OKO Technologies) is studied in order to characterize its utility as an adaptive optics element. The control procedure is based on knowledge of the membrane’s response under the action of each isolate electrode, i.e., the influence functions. The analysis of the mathematical techniques to obtain the control matrix gives useful information about the surfaces that are within the device’s range of production, thus predicting the...

Pulsed and CW Gaussian beam interactions with double negative metamaterial slabs

Richard W. Ziolkowski
The interactions of pulsed and continuous wave (CW) Gaussian beams with double negative (DNG) metatmaterials are considered. Sub-wavelength focusing of a diverging, normally incident pulsed Gaussian beam with a planar DNG slab is demonstrated. The negative angle of refraction behavior associated with the negative index of refraction exhibited by DNG metamaterials is demonstrated. The transmitted beam resulting from both 3-cycle and CW Gaussian beams that are obliquely incident on a DNG slab are shown to...

Pulsed and CW Gaussian beam interactions with double negative metamaterial slabs

Richard W. Ziolkowski
The interactions of pulsed and continuous wave (CW) Gaussian beams with double negative (DNG) metatmaterials are considered. Sub-wavelength focusing of a diverging, normally incident pulsed Gaussian beam with a planar DNG slab is demonstrated. The negative angle of refraction behavior associated with the negative index of refraction exhibited by DNG metamaterials is demonstrated. The transmitted beam resulting from both 3-cycle and CW Gaussian beams that are obliquely incident on a DNG slab are shown to...

Two-dimensional poling patterns for 3rd and 4th harmonic generation

Andrew H. Norton & C. Martijn De Sterke
We find globally optimal poling patterns for 2-dimensional χ(2) photonic crystals for 3rd and 4th harmonic generation.

Two-dimensional poling patterns for 3rd and 4th harmonic generation

Andrew H. Norton & C. Martijn De Sterke
We find globally optimal poling patterns for 2-dimensional χ(2) photonic crystals for 3rd and 4th harmonic generation.

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part I): System design, signal processing, and performance

Victor X.D. Yang, Maggie L. Gordon, Bing Qi, Julius Pekar, Stuart Lo, Emily Seng-Yue, Alvin Mok, Brian C. Wilson & I. Alex Vitkin
Improvements in real-time Doppler optical coherence tomography (DOCT), acquiring up to 32 frames per second at 250×512 pixels per image, are reported using signal processing techniques commonly employed in Doppler ultrasound imaging. The ability to measure a wide range of flow velocities, ranging from less than 20 µm/s to more than 10 cm/s, is demonstrated using an 1.3 µm DOCT system with flow phantoms in steady and pulsatile flow conditions. Based on full implementation of...

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part I): System design, signal processing, and performance

Victor X.D. Yang, Maggie L. Gordon, Bing Qi, Julius Pekar, Stuart Lo, Emily Seng-Yue, Alvin Mok, Brian C. Wilson & I. Alex Vitkin
Improvements in real-time Doppler optical coherence tomography (DOCT), acquiring up to 32 frames per second at 250×512 pixels per image, are reported using signal processing techniques commonly employed in Doppler ultrasound imaging. The ability to measure a wide range of flow velocities, ranging from less than 20 µm/s to more than 10 cm/s, is demonstrated using an 1.3 µm DOCT system with flow phantoms in steady and pulsatile flow conditions. Based on full implementation of...

Numerical techniques for excitation and analysis of defect modes in photonic crystals

Shangping Guo & Sacharia Albin
Two numerical techniques for analysis of defect modes in photonic crystals are presented. Based on the finite-difference time-domain method (FDTD), we use plane wave incidences and point sources for excitation and analysis. Using a total-field/scattered-field scheme, an ideal plane wave incident at different angles is implemented; defect modes are selectively excited and mode symmetries are probed. All modes can be excited by an incident plane wave along a non-symmetric direction of the crystal. Degenerate modes...

Numerical techniques for excitation and analysis of defect modes in photonic crystals

Shangping Guo & Sacharia Albin
Two numerical techniques for analysis of defect modes in photonic crystals are presented. Based on the finite-difference time-domain method (FDTD), we use plane wave incidences and point sources for excitation and analysis. Using a total-field/scattered-field scheme, an ideal plane wave incident at different angles is implemented; defect modes are selectively excited and mode symmetries are probed. All modes can be excited by an incident plane wave along a non-symmetric direction of the crystal. Degenerate modes...

Real-time second-harmonic-generation microscopy based on a 2-GHz repetition rate Ti:sapphire laser

Shi-Wei Chu, Tzu-Ming Liu, Chi-Kuang Sun, Cheng-Yung Lin & Huai-Jen Tsai
The problem of weak harmonic generation signal intensity limited by photodamage probability in optical microscopy and spectroscopy could be resolved by increasing the repetition rate of the excitation light source. Here we demonstrate the first photomultiplier-based real-time second-harmonic-generation microscopy taking advantage of the strongly enhanced nonlinear signal from a high-repetition-rate Ti:sapphire laser. We also demonstrate that the photodamage possibility in common biological tissues can be efficiently reduced with this high repetition rate laser at a...

Real-time second-harmonic-generation microscopy based on a 2-GHz repetition rate Ti:sapphire laser

Shi-Wei Chu, Tzu-Ming Liu, Chi-Kuang Sun, Cheng-Yung Lin & Huai-Jen Tsai
The problem of weak harmonic generation signal intensity limited by photodamage probability in optical microscopy and spectroscopy could be resolved by increasing the repetition rate of the excitation light source. Here we demonstrate the first photomultiplier-based real-time second-harmonic-generation microscopy taking advantage of the strongly enhanced nonlinear signal from a high-repetition-rate Ti:sapphire laser. We also demonstrate that the photodamage possibility in common biological tissues can be efficiently reduced with this high repetition rate laser at a...

Wavelength conversion bandwidth in fiber based optical parametric amplifiers

Ross W. McKerracher, Justin L. Blows & C. Martijn De Sterke
We propose a systematic approach to evaluating and optimising the wavelength conversion bandwidth and gain ripple of four-wave mixing based fiber optical wavelength converters. Truly tunable wavelength conversion in these devices requires a highly tunable pump. For a given fiber dispersion slope, we find an optimum dispersion curvature that maximises the wavelength conversion bandwidth.

Wavelength conversion bandwidth in fiber based optical parametric amplifiers

Ross W. McKerracher, Justin L. Blows & C. Martijn De Sterke
We propose a systematic approach to evaluating and optimising the wavelength conversion bandwidth and gain ripple of four-wave mixing based fiber optical wavelength converters. Truly tunable wavelength conversion in these devices requires a highly tunable pump. For a given fiber dispersion slope, we find an optimum dispersion curvature that maximises the wavelength conversion bandwidth.

Numerical study of electromagnetic waves interacting with negative index materials

Pavel Kolinko & David R. Smith
We study numerically the electromagnetic scattering properties of structures with negative indices of refraction. To perform this analysis, we utilize a commercial finite-element based electromagnetic solver (HFSS, Ansoft), in which a negative index material can be formed from mesh elements whose permittivity and permeability are both negative. In particular, we investigate the expected transmission characteristics of a finite beam incident on negative index prisms and lenses. We also confirm numerically the predicted superlens effect of...

Numerical study of electromagnetic waves interacting with negative index materials

Pavel Kolinko & David R. Smith
We study numerically the electromagnetic scattering properties of structures with negative indices of refraction. To perform this analysis, we utilize a commercial finite-element based electromagnetic solver (HFSS, Ansoft), in which a negative index material can be formed from mesh elements whose permittivity and permeability are both negative. In particular, we investigate the expected transmission characteristics of a finite beam incident on negative index prisms and lenses. We also confirm numerically the predicted superlens effect of...

Experimental and theoretical verification of focusing in a large, periodically loaded transmission line negative refractive index metamaterial

Ashwin K. Iyer, Peter C. Kremer & George V. Eleftheriades
We have previously shown that a new class of Negative Refractive Index (NRI) metamaterials can be constructed by periodically loading a host transmission line medium with inductors and capacitors in a dual (high-pass) configuration. A small planar NRI lens interfaced with a Positive Refractive Index (PRI) parallel-plate waveguide recently succeeded in demonstrating focusing of cylindrical waves. In this paper, we present theoretical and experimental data describing the focusing and dispersion characteristics of a significantly improved...

Experimental and theoretical verification of focusing in a large, periodically loaded transmission line negative refractive index metamaterial

Ashwin K. Iyer, Peter C. Kremer & George V. Eleftheriades
We have previously shown that a new class of Negative Refractive Index (NRI) metamaterials can be constructed by periodically loading a host transmission line medium with inductors and capacitors in a dual (high-pass) configuration. A small planar NRI lens interfaced with a Positive Refractive Index (PRI) parallel-plate waveguide recently succeeded in demonstrating focusing of cylindrical waves. In this paper, we present theoretical and experimental data describing the focusing and dispersion characteristics of a significantly improved...

Mid infrared pulse shaping by optical parametric amplification and its application to optical free induction decay measurement

Howe-Siang Tan & Warren S. Warren
We produce microjoule energy shaped mid infrared (MIR) pulses in an optical parametric amplification (OPA) process by imposing the phase and amplitude profile of an arbitrarily shaped pump pulse onto the idler pulse. Using phase locked pulses created using this technique, we measure for the first time, complex optical free induction decay (OFID) of the vibrational coherence of a C-H stretching mode.

Mid infrared pulse shaping by optical parametric amplification and its application to optical free induction decay measurement

Howe-Siang Tan & Warren S. Warren
We produce microjoule energy shaped mid infrared (MIR) pulses in an optical parametric amplification (OPA) process by imposing the phase and amplitude profile of an arbitrarily shaped pump pulse onto the idler pulse. Using phase locked pulses created using this technique, we measure for the first time, complex optical free induction decay (OFID) of the vibrational coherence of a C-H stretching mode.

Ultrafast all optical switching by use of pulse trapping across zero-dispersion wavelength

Norihiko Nishizawa & Toshio Goto
Ultrafast all optical switching by use of pulse trapping across zero dispersion wavelength in optical fiber is demonstrated both experimentally and numerically for the first time. Only an arbitrary single pulse among four pulses with temporal separation of about 1.5 ps is successfully picked off with almost perfect extinction ratio. The spectrogram of the optical switching is directly observed using the X-FROG technique. The characteristics of all optical switching are analyzed numerically by the use...

Ultrafast all optical switching by use of pulse trapping across zero-dispersion wavelength

Norihiko Nishizawa & Toshio Goto
Ultrafast all optical switching by use of pulse trapping across zero dispersion wavelength in optical fiber is demonstrated both experimentally and numerically for the first time. Only an arbitrary single pulse among four pulses with temporal separation of about 1.5 ps is successfully picked off with almost perfect extinction ratio. The spectrogram of the optical switching is directly observed using the X-FROG technique. The characteristics of all optical switching are analyzed numerically by the use...

Dynamical mapping of the human cardiomagnetic field with a room-temperature, laser-optical sensor

G. Bison, R. Wynands & A. Weis
The magnetic field produced by the human heart carries valuable information for medical research, as well as for diagnostics and screening for disease. We have developed an optical method that allows us to produce movies of the temporal dynamics of the human cardiomagnetic field map. While such movies have been generated before with the help of SQUID magnetometers, our technique operates at room temperature and promises substantial economic advantages.

Wide band interferometry for thickness measurement

Santiago Costantino, Oscar E. Martínez & Jorge R. Torga
In this work we present the concept of wide band interferometry as opposed to white-light interferometry to introduce a thickness measurement method that gains precision when the bandwidth is reduced to an adequate compromise in order to avoid the distortions arising from the material dispersion. The use of the widest possible band is a well established dogma when the highest resolution is desired in distance measurements with white-light interferometry. We will show that the dogma...

Wide band interferometry for thickness measurement

Santiago Costantino, Oscar E. Martínez & Jorge R. Torga
In this work we present the concept of wide band interferometry as opposed to white-light interferometry to introduce a thickness measurement method that gains precision when the bandwidth is reduced to an adequate compromise in order to avoid the distortions arising from the material dispersion. The use of the widest possible band is a well established dogma when the highest resolution is desired in distance measurements with white-light interferometry. We will show that the dogma...

Resource Types

  • Collection
    176

Publication Year

  • 2003
    176