A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation in photonic crystal fiber

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

Objective: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. Design: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Settings Research laboratory. Participants: Convenience sample of normal human subjects. Main Outcome Measures: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. Results: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10- μm depth resolution. Conclusion: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Optical Coherence Tomography of the Human Retina

Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

In Vivo Endoscopic Optical Biopsy with Optical Coherence Tomography

Quadrature squeezed light generation with optical pulses in a fiber loop mirror is analyzed through computer simulation. The effect of guided acoustic wave Brillouin scattering (GAWBS) in optical fibers as well as those of nonlinearities and chromatic dispersions are considered for the first time. The relation between the GAWBS noise and the optical pulse width is discussed in detail. It is found that the nearly fundamental soliton pulse is optimum to get the largest squeezing even if the GAWBS noise is effective. The broadened pulses suffer larger degradation of squeezing due to this noise.

Effect of Guided Acoustic Wave Brillouin Scattering on Pulsed Squeezing in Optical Fibers with Nonlinearity and Dispersion

Optical coherence tomography (OCT) is a non invasive optical imaging technology for micron-scale cross-sectional
imaging of biological tissue and materials Although OCT has many advantages in medical equipments, low penetration
depth is a serious limitation for other applications To realize the ultrahigh resolution and the high penetration depth at
the same time, it is effective to choose the proper wavelength to maximize the light penetration and enhance the image
contrast at deeper depths Recently, we have demonstrated ultrahigh resolution and high penetration depth OCT by use
of all-fiber based Gaussian shaped supercontinuum source at 17 μm center wavelength Gaussian-like supercontinuum
with 360 nm bandwidth at center wavelength of 17 μm was generated by ultrashort pulse Er doped fiber laser based
system In this paper, using 08 μm and 13 μm SC sources in addition to the 17 μm SC source, we have investigated the
wavelength dependence of ultrahigh resolution OCT in terms of penetration depth Longitudinal resolutions at each
wavelength region are almost 46 μm in air The obtained sensitivity was 95 dB for all wavelength regions We
confirmed the difference of imaging contrast and penetration depth with hamster's cheek pouch and so on As the
wavelength was increased, the magnitude of penetration depth was increased for these samples

Experimental investigation of wavelength dependence of penetration depth and imaging contrast for ultrahigh-resolution optical coherence tomography

Here we report the demonstration of a spectral peaking phenomenon in a fiber laser oscillator. An HCN gas cell was inserted in an ultrashort-pulse Er-doped fiber laser with single-wall carbon nanotubes. Sech2-shaped ultrashort pulses with intense multiple sharp spectral peaks were stably generated. When the generated pulses were coupled into highly nonlinear fiber, enhanced multiple spectral peaks were generated by periodical spectral peaking in the optical fiber. The characteristics and physical mechanism of spectral peaking in the fiber laser were investigated via numerical simulations. As the magnitude of absorption was increased, the magnitude of the generated spectral peaks increased almost exponentially. It was clarified that the spectral peaks were generated through the accumulation of filtering components generated in each round trip.

Spectral peaking in an ultrashort-pulse fiber laser oscillator with a molecular gas cell.

High power Tm-doped ultrashort pulse fiber laser operated at 1.9 um was demonstrated using single wall carbon nanotube dispersed in polyimide film. A 1.7 nJ, 36 mW high power dissipative soliton pulse was obtained.

Dispersion Managed, High Power TM-Doped Ultrashort Pulse Fiber Laser at 1.9 UM Using Single Wall Carbon Nanotube Polyimide Film

Practical all fiber three dimensional measurement system is demonstrated. The sensitivity and axial resolution are as high as 85 dB and 2 mum. The high resolution images of metaric samples are clearly obtained from - a few meter long distance at the speed of 52 points/s.

Norihiko Nishizawa

Papers

Effect of Guided Acoustic Wave Brillouin Scattering on Pulsed Squeezing in Optical Fibers with Nonlinearity and Dispersion

Experimental investigation of wavelength dependence of penetration depth and imaging contrast for ultrahigh-resolution optical coherence tomography

Spectral peaking in an ultrashort-pulse fiber laser oscillator with a molecular gas cell.

Dispersion Managed, High Power TM-Doped Ultrashort Pulse Fiber Laser at 1.9 UM Using Single Wall Carbon Nanotube Polyimide Film

Highly-Sensitive and High-Resolution Three Dimensional Measurement in All Fiber System