1. Articles in category: Broadband Sources

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    1. Supercontinuum generation for ultrahigh-resolution optical coherence tomography at wavelength of 0.8µm using carbon nanotube fiber laser and similariton amplifier

      Supercontinuum generation for ultrahigh-resolution optical coherence tomography at wavelength of 0.8µm using carbon nanotube fiber laser and similariton amplifier

      We demonstrated supercontinuum (SC) generation for ultrahigh-resolution optical coherence tomography (UHR-OCT) in the 0.8 µm wavelength region using an ultrashort-pulse fiber laser system. An Er-doped ultrashort-pulse fiber laser with single-wall carbon nanotubes was developed as the seed pulse source. A 46 fs, highest quality, pedestal-free, clean, ultrashort pulse was generated with a similariton amplifier. Then, a 60 fs ideal ultrashort pulse was generated at a wavelength of 0.8 µm with a second-harmonic generation (SHG) crystal, and a Gaussian-like SC was generated in a photonic crystal fiber. UHR-OCT was demonstrated using the generated SC, and precise images of a ...

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    2. Noise characterization of supercontinuum sources for low-coherence interferometry applications

      Noise characterization of supercontinuum sources for low-coherence interferometry applications

      We examine the noise properties of supercontinuum light sources when used in low-coherence interferometry applications. The first application is a multiple-scattering low-coherence interferometry (ms2/LCI) system, where high power and long image acquisition times are required to image deep into tissue. For this system, we compare the noise characteristics of two supercontinuum sources from different suppliers. Both sources have long-term drift that limits the amount of time over which signal averaging is advantageous for reducing noise. The second application is a high-resolution optical coherence tomography system, where broadband light is needed for high axial resolution. For this system, we compare ...

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    3. Supercontinuum optimization for dual-soliton based light sources using genetic algorithms in a grid platform

      Supercontinuum optimization for dual-soliton based light sources using genetic algorithms in a grid platform

      We present a numerical strategy to design fiber based dual pulse light sources exhibiting two predefined spectral peaks in the anomalous group velocity dispersion regime. The frequency conversion is based on the soliton fission and soliton self-frequency shift occurring during supercontinuum generation. The optimization process is carried out by a genetic algorithm that provides the optimum input pulse parameters: wavelength, temporal width and peak power. This algorithm is implemented in a Grid platform in order to take advantage of distributed computing. These results are useful for optical coherence tomography applications where bell-shaped pulses located in the second near-infrared window are ...

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    4. Broadband fiber-optical parametric amplification for ultrafast time-stretch imaging at 1.0 um

      Broadband fiber-optical parametric amplification for ultrafast time-stretch imaging at 1.0 um

      We demonstrate a broadband all-fiber-optical parametric amplifier for ultrafast time-stretch imaging at 1.0 μm, featured by its compact design, alignment-free, high efficiency, and flexible gain spectrum through fiber nonlinearity- and dispersion-engineering: specifically on a dispersion-stabilized photonic-crystal fiber (PCF) to achieve a net gain over 20 THz (75 nm) and a highest gain of ∼ 6000 (37.5 dB). Another unique feature of the parametric amplifier, over other optical amplifiers, is the coherent generation of a synchronized signal replica (called idler) that can be exploited to offer an extra 3-dB gain by optically superposing the signal and idler. It further enhances ...

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    5. Generation of an octave-spanning supercontinuum in highly nonlinear fibers pumped by noise-like pulse

      Generation of an octave-spanning supercontinuum in highly nonlinear fibers pumped by noise-like pulse

      A supercontinuum generation system is developed, which consists of an erbium-doped fiber ring laser, an erbium-doped fiber amplifier, and a 100-m highly nonlinear fiber. Through nonlinear polarization rotation, the fiber ring laser generates a train of noise-like pulses in the form of repetitive picosecond pulse packets consisting of femtosecond noise-like fine temporal structures. The noise-like pulses are amplified before being sent into the highly nonlinear fiber. As a result, an octave-spanning supercontinuum from 1177 nm to 2449 nm is obtained, which has a 20-dB spectral width of 980 nm. Because of the nonlinearity of the fiber amplifier, the duration of ...

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    6. The calculation of the coherence time of spectral supercontinuum at the output of the fused silica with different parameters of the initial pulse

      The calculation of the coherence time of spectral supercontinuum at the output of the fused silica with different parameters of the initial pulse

      In this paper the dependence of the coherence time of a femtosecond spectral supercontinuum from different initial pulse parameters - wavelength, peak intensity and duration is studied. The obtained dependences and ratio of the coherence time of the pulse to the duration of the pulse at the output are analyzed. It is shown that in the case of femtosecond spectral supercontinuum generation in fused silica in the areas of normal, anomalous and zero group velocity dispersion, with an increase of the central wavelength of the femtosecond laser pulse at the input, the coherence time of the radiation with ultra-wide spectrum is ...

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    7. Supercontinuum generation in silicon nanowire embedded photonic crystal fibers with different core geometries

      Supercontinuum generation in silicon nanowire embedded photonic crystal fibers with different core geometries

      We design various silicon nanowire embedded photonic crystal fibers (SN-PCFs) with different core geometries, namely, circular, rectangular and elliptical using finite element method. Further, we study the optical properties such as group velocity dispersion (GVD), third order dispersion (TOD) of x and y-polarized modes and effective nonlinearity for a wavelength range from 0.8 to 1.6 μm. The proposed structure exhibits almost flat GVD (0.8 to 1.2 μm wavelength), zero GVD (≈ 1.31 μm) and small TOD (0.00069 ps 3 /m) at 1.1 μm wavelength and high nonlinearity (2916 W -1 m -1 ) at 0 ...

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    8. Broadband Or MID-INFRARED Fiber Light Sources

      Broadband Or MID-INFRARED Fiber Light Sources

      An optical system for use in an imaging procedure includes one or more semiconductor diodes configured to generate an input signal beam with a wavelength shorter than 2.5 microns that is amplified and communicated through optical fiber(s) to a nonlinear element configured to broaden the spectral width to at least 50 nm through a nonlinear effect. A subsystem includes lenses or mirrors to deliver an output beam having a broadened spectrum to an Optical Coherence Tomography apparatus with a sample and reference arm to perform imaging for characterizing the sample. The delivered output beam has a temporal duration ...

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    9. Characterizing the resolvability of real superluminescent diode sources for application to optical coherence tomography using a low coherence interferometry model

      Characterizing the resolvability of real superluminescent diode sources for application to optical coherence tomography using a low coherence interferometry model

      The axial resolution is a critical parameter in determining whether optical coherent tomography (OCT) can be used to resolve specific features in a sample image. Typically, measures of resolution have been attributed to the light source characteristics only, including the coherence length and the point spread function (PSF) width of the OCT light sources. The need to cost effectively visualize the generated PSF and OCT cross-correlated interferogram (A-scan) using many OCT light sources have led to the extrinsic evolution of the OCT simulation model presented. This research indicated that empirical resolution in vivo , as well as depending on the light ...

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    10. Fabrication and Characteristics of Ce-Doped Fiber for High-Resolution OCT Source

      Fabrication and Characteristics of Ce-Doped Fiber for High-Resolution OCT Source

      The fabrication of Ce-doped fibers (CeDFs) is demonstrated by drawing-tower method employing rod-in-tube technique. The fluorescence spectrum of CeDFs with a 16-μm core exhibited a 160-nm broadband emission with 1.45-μm axial resolution. This CeDF may be functioned as a high-resolution light source for optical coherence tomography applications.

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    11. Yale University Receives NIH Grant for Development of a New Light Sources for Parallel Optical Coherence Tomography

      Yale University Receives NIH Grant for Development of a New Light Sources for Parallel Optical Coherence Tomography

      Yale University Receivesd a 2014 NIH Grant for $201,881 for Development of a New Light Sources for Parallel Optical Coherence Tomography. The principal investigator is Michel Choma. The program began in 2013 and ends in 2015. Below is a summary of the proposed work. The ability of optical coherence tomography (OCT) to perform high-speed, micron-scale, cross-sectional imaging has transformed ophthalmic medicine and has the potential to transform cardiovascular, gastrointestinal, pulmonary, and dermatological medicine. Current OCT systems use raster scanning, a serial method for acquiring depth reflectivity profiles at different locations on a sample. Shifting the paradigm fro serial to ...

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    12. Numerical analysis of AlGaAs/GaAs multi-quantum well superluminescent diodes

      Numerical analysis of AlGaAs/GaAs multi-quantum well superluminescent diodes

      In this paper, we have investigated numerically AlGaAs/GaAs multi-quantum well superluminescent diodes. In these devices the dependence of optical gain, output power on the cavity length and the density states have been analyzed. It is observed that the optical gain and its FWHM bandwidth increase with increasing the density state. Furthermore, the output power increases with increasing the cavity length, whereas the FWHM bandwidth decreases.

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    13. Feature Of The Week 6/29/14: Development of a high power supercontinuum source in the 1.7 um wavelength region for highly penetrative ultrahigh-resolution optical coherence tomography

      Feature Of The Week 6/29/14: Development of a high power supercontinuum source in the 1.7 um wavelength region for highly penetrative ultrahigh-resolution optical coherence tomography

      Optical coherence tomography (OCT) is an essential imaging technique especially in ophthalmology. However, the shallow penetration depth of about 1-2 mm limits the expansion of OCT applications. Recently, the OCT systems operating in 1.7 um wavelength region have been demonstrated to improve the penetration depth. In the longer wavelength region, the signal attenuation due to Rayleigh scattering is reduced compared to that in the conventional 0.8-1.3 um wavelength region. In this work, the authors developed a high power supercontinuum (SC) source at a center wavelength of 1.7 um to demonstrate highly penetrative ultrahigh resolution (UHR) OCT ...

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    14. Short cavity active mode locking fiber laser for optical sensing and imaging

      Short cavity active mode locking fiber laser for optical sensing and imaging

      We demonstrate a highly linear wavenumber- swept active mode locking (AML) fiber laser for optical sensing and imaging without any wavenumber-space resampling process. In this all-electric AML wavenumber-swept mechanism, a conventional wavelength selection filter is eliminated and, instead, the suitable programmed electric modulation signal is directly applied to the gain medium. Various types of wavenumber (or wavelength) tunings can be implemented because of the filter-less cavity configuration. Therefore, we successfully demonstrate a linearly wavenumber-swept AML fiber laser with 26.5 mW of output power to obtain an in-vivo OCT image at the 100 kHz swept rate.

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    15. Supercontinuum generation in nonlinear fibers using high-energy figure-of-eight mode-locked fiber laser for SD-OCT application

      Supercontinuum generation in nonlinear fibers using high-energy figure-of-eight mode-locked fiber laser for SD-OCT application

      Generation of flat and broadband supercontinum is demonstrated in an all fiber system using the high-energy noise-like pulses from a stable figure-of-eight fiber laser and nonlinear fibers. This SC source is successfully applied to the spectral domain optical coherence tomography (SD-OCT). The axial resolution is significantly improved compared with the case of the superluminescent diode source. SD-OCT imaging is also demonstrated.

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    16. Maximizing the bandwidth of coherent, mid-IR supercontinuum using highly nonlinear aperiodic nanofibers

      Maximizing the bandwidth of coherent, mid-IR supercontinuum using highly nonlinear aperiodic nanofibers

      We describe in detail a new procedure of maximizing the bandwidth of mid-infrared (mid-IR) supercontinuum (SC) in highly nonlinear microstructured As 2 Se 3 and tellurite aperiodic nanofibers. By introducing aperiodic rings of first and secondary air holes into the cross-sections of our microstructured fiber designs, we achieve flattened and all-normal dispersion profiles over much broader bandwidths than would be possible with simple periodic designs. These fiber designs are optimized for efficient, broadband, and coherent SC generation in the mid-IR spectral region. Numerical simulations show that these designs enable the generation of a SC spanning over 2290 nm extending from ...

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    17. Supercontinuum generation in optical fibers and its biomedical applications

      Supercontinuum generation in optical fibers and its biomedical applications

      A microstructured optical fiber was first used in 2000 for supercontinuum generation. Since then, enormous progress has been made in understanding, controlling, and marketing fiber-based supercontinuum sources. In particular, biomedical applications of such sources are revolutionizing the field of medical imaging. In this talk I review the recent progress in this area and describe how a supercontinuum can be employed for biomedical imaging using the techniques known as coherent anti-Stokes Raman scattering, stimulated emission-depletion microscopy, and optical coherence tomography.

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    18. Supercontinuum Promises Game-Changing New Tools for Medicine, Research, More

      Supercontinuum Promises Game-Changing New Tools for Medicine, Research, More

      Supercontinuum generation has already found uses in chemistry and biology, but its discoverer says what's on the horizon is even more exciting. The technology is featured in new freely accessible multimedia presentations published by SPIE, the international society for optics and photonics.

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    19. Photonic Device And Optical Coherence Tomography Apparatus Including The Photonic Device As Light Source

      Photonic Device And Optical Coherence Tomography Apparatus Including The Photonic Device As Light Source

      Provided is a photonic device in which emission intensity in a short wavelength region is suppressed even in the case of increasing carrier injection density so as to obtain a wide spectrum half-maximum width as well as a high output. The photonic device includes: a first cladding layer; a second cladding layer; and an active layer including an emitting layer and a barrier layer and being provided between the first cladding layer and the second cladding layer, the emitting layer emitting light in a spectrum having a center wavelength λc and a spectrum half-maximum width Δλ, in which at least one ...

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    20. Light Source And Optical Coherence Tomography Apparatus Including The Light Source

      Light Source And Optical Coherence Tomography Apparatus Including The Light Source

      A light source includes an upper electrode layer, a lower electrode layer, and an active layer interposed therebetween. At least one of the upper and lower electrode layers is divided into a plurality of electrodes separated from each other in an in-plane direction of the active layer. The separated electrodes independently inject current into a plurality of different regions in the active layer. The light source emits light by injecting current from the upper and lower electrode layers into the active layer, guide the light in the in-plane direction, and output the light. The plurality of different regions in the ...

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    21. Optical Semiconductor Device, Driving Method Thereof, And Optical Coherence Tomography Apparatus Having The Optical Semiconductor Device

      Optical Semiconductor Device, Driving Method Thereof, And Optical Coherence Tomography Apparatus Having The Optical Semiconductor Device

      The present invention provides an optical semiconductor device which can make a wavelength band of emitted light wider than that of a conventional optical semiconductor device. The optical semiconductor device includes: an active layer including a multiple quantum well structure; and at least one electrode pair for injecting an electric current into the active layer, wherein the multiple quantum well structure has a first quantum well and a second quantum well which is different from the first quantum well, and the first quantum well and the second quantum well are mutually different in at least two out of a composition ...

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    22. Filtered ASE swept source for OCT medical imaging

      Filtered ASE swept source for OCT medical imaging

      An integrated swept wavelength optical source uses a filtered ASE signal with an optical amplifier and tracking filter. This source comprises a micro optical bench, a source for generating broadband light, a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a narrowband tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier. A self-tracking arrangement is also possible where a single tunable filter ...

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    23. Development of a high power supercontinuum source in the 1.7 μm wavelength region for highly penetrative ultrahigh-resolution optical coherence tomography

      Development of a high power supercontinuum source in the 1.7 μm wavelength region for highly penetrative ultrahigh-resolution optical coherence tomography

      We developed a high power supercontinuum source at a center wavelength of 1.7 μm to demonstrate highly penetrative ultrahigh-resolution optical coherence tomography (UHR-OCT). A single-wall carbon nanotube dispersed in polyimide film was used as a transparent saturable absorber in the cavity configuration and a high-repetition-rate ultrashort-pulse fiber laser was realized. The developed SC source had an output power of 60 mW, a bandwidth of 242 nm full-width at half maximum, and a repetition rate of 110 MHz. The average power and repetition rate were approximately twice as large as those of our previous SC source [ 20 ]. Using the developed ...

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    1-24 of 212 1 2 3 4 5 6 7 8 9 »
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