1. Articles in category: Broadband Sources

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    1. GaAs-Based Superluminescent Light-Emitting Diodes with 290-nm Emission Bandwidth by Using Hybrid Quantum Well/Quantum Dot Structures

      GaAs-Based Superluminescent Light-Emitting Diodes with 290-nm Emission Bandwidth by Using Hybrid Quantum Well/Quantum Dot Structures

      A high-performance superluminescent light-emitting diode (SLD) based upon a hybrid quantum well (QW)/quantum dot (QD) active element is reported and is assessed with regard to the resolution obtainable in an optical coherence tomography system. We report on the appearance of strong emission from higher order optical transition from the QW in a hybrid QW/QD structure. This additional emission broadening method contributes significantly to obtaining a 3-dB linewidth of 290 nm centered at 1200 nm, with 2.4 mW at room temperature.

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    2. Small, inexpensive, and incredibly resilient: A new femtosecond laser for industry

      Small, inexpensive, and incredibly resilient: A new femtosecond laser for industry

      A team at the University of Warsaw, Faculty of Physics has created a laser capable of generating ultrashort pulses of light even under extremely difficult external conditions. This unique combination of precision and resilience is due to the fact that the whole process of generating femtosecond laser pulses takes place within a specially-selected optical fiber. Its appearance seems quite inconspicuous: just a flat, rectangular box, tens of centimeters across and about the same height, with a thin, shiny-tipped "thread" leading out of it, so long that it is rolled up into a coil. This small instrument, built by physicists from ...

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    3. High-speed ultrahigh-resolution spectral domain optical coherence tomography using high-powersupercontinuum at 0.8 µm wavelength

      High-speed ultrahigh-resolution spectral domain optical coherence tomography using high-powersupercontinuum at 0.8 µm wavelength

      We demonstrated high-speed ultrahigh-resolution (UHR) optical coherence tomography (OCT) in the 800 nm wavelength region. A high-power coherent supercontinuum (SC) and a high-speed line scan camera were used to construct a spectral domain OCT. The axial resolution was 3.1 µm in air and 2.3 µm in tissue. The dependence of sensitivity on the SC power and A-scan rate was examined. For the A-scan rate of 70 kHz, the sensitivity of 104 dB was achieved for the SC power higher than 60 mW. High-speed in vivo UHR-OCT imaging was demonstrated for zebrafish embryo and swimming medaka.

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    4. Broadband infrared light emitting device

      Broadband infrared light emitting device

      There is provided a broadband infrared light emitting device that radiates infrared light having a band broader than a conventional broadband infrared light emitting device. [MEANS FOR SOLVING] The broadband infrared light emitting device at least includes: a light source 4 that emits first excitation light .lamda.1 in a first wavelength range; a first glass phosphor 51 that has an excitation band in a first wavelength range, and when the first excitation light .lamda.1 is incident thereon, emits second excitation light .lamda.2 in a second wavelength range and first infrared light .lamda.3 in a third wavelength ...

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    5. Broadband supercontinuum generation using a hollow optical fiber filled with copper-ion-modified DNA

      Broadband supercontinuum generation using a hollow optical fiber filled with copper-ion-modified DNA

      We experimentally demonstrated supercontinuum generation through a hollow core photonic bandgap fiber (HC-PBGF) filled with DNA nanocrystals modified by copper ions in a solution. Both double-crossover nano DNA structure and copper-ion-modified structure provided a sufficiently high optical nonlinearity within a short length of hollow optical fiber. Adding a higher concentration of copper ion into the DNA nanocrystals, the bandwidth of supercontinuum output was monotonically increased. Finally, we achieved the bandwidth expansion of about 1000 nm to be sufficient for broadband multi-spectrum applications.

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    6. Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm

      Optical characterization of In-flushed InAs/GaAs quantum dots emitting a broadband spectrum with multiple peaks at ~1 μm

      We investigated optical properties of In-flushed InAs quantum dots (QDs) grown on a GaAs substrate by molecular beam epitaxy. By using the In-flush technique for setting the height of self-assembled InAs QDs, we have tuned the emission wavelength of InAs QDs to the ~1 μm regime, which can be utilized as a non-invasive and deeply penetrative probe for biological and medical imaging systems. The controlled emission exhibited a broadband spectrum comprising multiple peaks with an interval of approximately 30 meV. We examined the origin of the multiple peaks using spectral and time-resolved photoluminescence, and concluded that it is attributed to ...

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    7. Mid-infrared photonics: Spiral superluminescent emitter

      Mid-infrared photonics: Spiral superluminescent emitter

      Superluminescent (SL) light sources, which offer the beneficial combination of a broad emission bandwidth with low temporal and high spatial coherence, have many potential industrial and medical applications. In particular, mid-infrared (MIR) SL light sources that are suitable for use in an optical coherence tomography system would be attractive for…

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    8. Imaging of spectral-domain optical coherence tomography using a superluminescent diode based on InAs quantum dots emitting broadband spectrum with Gaussian-like shape

      Imaging of spectral-domain optical coherence tomography using a superluminescent diode based on InAs quantum dots emitting broadband spectrum with Gaussian-like shape

      We developed a low-coherence light source based on self-assembled InAs quantum dots (QDs) with controlled emission wavelengths and applied it to optical coherence tomography (OCT) imaging. A current-driven superluminescent diode (SLD) light source including four layers of QDs exhibits a broadband (80-nm-bandwidth) emission centered at approximately 1.2 µm with a Gaussian-like spectral shape at room temperature. Spectral-domain OCT (SD-OCT) using the QD-SLD as a light source was developed and imaging with the SD-OCT was demonstrated. The axial resolution was estimated to be approximately 8 µm in air and no apparent side lobes appeared beside the point spread function, indicating ...

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    9. Broadband generation of mid IR, coherent continua with optical fibers

      Broadband generation of mid IR, coherent continua with optical fibers

      Coherent and compact supercontinuum light sources for the mid IR spectral regime are disclosed and exemplary applications thereof. The supercontinuum generation is based on the use of highly nonlinear fibers or waveguides. In at least one embodiment the coherence of the supercontinuum sources is increased using low noise mode locked short pulse sources. Compact supercontinuum light sources can be constructed with the use of passively mode locked fiber or diode lasers. Wavelength tunable sources can be constructed using appropriate optical filters or frequency conversion sections. Highly coherent supercontinuum sources further facilitate coherent detection schemes and can improve the signal/noise ...

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    10. Frequency combs in molecular fingerprint region

      Frequency combs in molecular fingerprint region

      Silicon nanowire optical waveguides dramatically broaden mid-infrared frequency comb spectra, scientists report. Frequency combs are commercially available in the visible and near-infrared spectral ranges. The mid-infrared spectral region (2-20?m), however, is still emerging. Many applications in spectroscopy, material science, security and industry process control, or chemical, biological and medical sensing would straightforwardly take advantage of mid-infrared photonics devices of higher performance.

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    11. High resolution Fourier domain optical coherence tomography in the 2 um wavelength range using a broadband supercontinuum source

      High resolution Fourier domain optical coherence tomography in the 2 um wavelength range using a broadband supercontinuum source

      A 220 nm bandwidth supercontinuum source in the two-micron wavelength range has been developed for use in a Fourier domain optical coherence tomography (FDOCT) system. This long wavelength source serves to enhance probing depth in highly scattering material with low water content. We present results confirming improved penetration depth in high opacity paint samples while achieving the high axial resolution needed to resolve individual paint layers. This is the first FDOCT developed in the 2 μm wavelength regime that allows fast, efficient capturing of 3D image cubes at a high axial resolution of 13 μm in air (or 9 μm ...

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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. 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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    18. 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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    19. 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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    20. 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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    21. 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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    22. 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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    23. 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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