1. Articles in category: Broadband Sources

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    1. Study of low-peak-power highly coherent broadband supercontinuum generation through a dispersion-engineered Si-rich silicon nitride waveguide

      Study of low-peak-power highly coherent broadband supercontinuum generation through a dispersion-engineered Si-rich silicon nitride waveguide

      Since the first observation by Alfano and Shapiro in the 1970s [Phys. Rev. Lett. 24 , 584 (1970) [ CrossRef ] ], supercontinuum generation study has become an attractive research area in the field of broadband light source design, including its use in various applications associated with nonlinear optics in recent years. In this work, the numerical demonstration of ultrabroadband supercontinuum generation in the mid-infrared (MIR) region via the use of complementary metal-oxide semiconductor compatible Si-rich silicon nitride as the core in a planar waveguide design employing one of two materials, either L i N b O 3 LiNbO3 or M g F 2 ...

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    2. Noise reduction in supercontinuum sources for OCT by single-pulse spectral normalization

      Noise reduction in supercontinuum sources for OCT by single-pulse spectral normalization

      Supercontinuum (SC) sources offer high illumination power from a single-mode fiber with large spectral bandwidth including the visible spectrum, which is a growing application area for optical coherence tomography (OCT). However, SC spectra suffer from pulse-to-pulse variations, increasing noise in the resulting images. By simultaneously collecting a normalization spectrum, OCT image noise can be reduced by more than half (7 dB) for single pulses without any pulse averaging using only simple optical components.

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    3. Sources of optical radiation and methods for providing low-speckle optical radiation, and systems and methods using them

      Sources of optical radiation and methods for providing low-speckle optical radiation, and systems and methods using them

      The present disclosure relates more particularly to active optical fibers, amplified spontaneous emission (ASE) sources using such active optical fibers, and imaging and detection systems and methods using such ASE sources. In one aspect, the disclosure provides an active optical fiber that includes a rare earth-doped gain core configured to emit radiation at at least a peak wavelength emitted wavelength when pumped with pump radiation having a pump wavelength; a pump core surrounding the gain core; and a cladding surrounding the pump core, wherein the value M=16R.sup.2(NA).sup.2/.lamda..sup.2 in which R is ...

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    4. Supercontinuum generation in a chalcogenide all-solid hybrid microstructured optical fiber

      Supercontinuum generation in a chalcogenide all-solid hybrid microstructured optical fiber

      We report the fabrication of a chalcogenide all-solid hybrid microstructured optical fiber and its application in supercontinuum generation for the first time, to the best of our knowledge. The fiber possesses all-normal and flattened chromatic dispersion, making it highly potential for broad and coherent supercontinuum generation. By pumping the fiber with a femtosecond laser at 3, 4, and 5 µm, broad supercontinua with good spectral flatness are generated. The broadest SC spectrum extending from 2.2 to 10 µm at -20 dB level was obtained when the fiber was pumped at 5 µm with an input power of 3.9 ...

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    5. Supercontinuum light source comprising tapered microstructured optical fiber

      Supercontinuum light source comprising tapered microstructured optical fiber

      The invention relates to a supercontinuum light source comprising a microstructured optical fiber and a pump light source. The microstructured optical fiber comprises a core and a cladding region surrounding the core, as well as a first fiber length section, a second fiber length section and an intermediate fiber length section between said first and second fiber length sections. The first fiber length section comprises a core with a first characteristic core diameter. The second fiber length section comprises a core with a second characteristic core diameter, smaller than said first characteristic core diameter, where said second characteristic core diameter ...

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      Mentions: NKT Photonics
    6. Broadened Bandwidth Amplified Spontaneous Emission from Blue GaN-Based Short-Cavity Superluminescent Light-Emitting Diodes

      Broadened Bandwidth Amplified Spontaneous Emission from Blue GaN-Based Short-Cavity Superluminescent Light-Emitting Diodes

      We report broad bandwidth blue superluminescent light-emitting diodes (SLEDs) based on a short-cavity active region. The dependencies of amplified spontaneous emission (ASE) output power and gain bandwidth on cavity length were investigated in devices whose gain medium consists of a ridge waveguide with embedded InGaN/GaN quantum wells sandwiched between one etched facet coated with a high reflectivity distributed Bragg mirror and one cleaved facet with an anti-reflection coating. 250 μm-long blue SLEDs exhibit a spectral bandwidth up to 7.5 nm at 1.72 mW output power at a wavelength of 427 nm. As cavity length decreases, the bandwidth ...

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    7. GaAs-Based InPBi Quantum Dots for High Efficiency Super-Luminescence Diodes

      GaAs-Based InPBi Quantum Dots for High Efficiency Super-Luminescence Diodes

      InPBi exhibits broad and strong photoluminescence at room temperature, and is a potential candidate for fabricating super-luminescence diodes applied in optical coherence tomography. In this paper, the strained InPBi quantum dot (QD) embedded in the AlGaAs barrier on a GaAs platform is proposed to enhance the light emission efficiency and further broaden the photoluminescence spectrum. The finite element method is used to calculate the strain distribution, band alignment and confined levels of InPBi QDs. The carrier recombinations between the ground states and the deep levels are systematically investigated. A high Bi content and a flat QD shape are found preferable ...

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    8. Ultrahigh-resolution optical coherence tomography/angiography with an economic and compact supercontinuum laser

      Ultrahigh-resolution optical coherence tomography/angiography with an economic and compact supercontinuum laser

      In this study, a Q-switch pumped supercontinuum laser (QS-SCL) is used as a light source for in vivo imaging via ultrahigh-resolution optical coherence tomography and angiography (UHR-OCT/OCTA). For this purpose, an OCT system based on a spectral-domain detection scheme is constructed, and a spectrometer with a spectral range of 635 − 875 nm is designed. The effective full-width at half maximum of spectrum covers 150 nm, and the corresponding axial and transverse resolutions are 2 and 10 µm in air, respectively. The relative intensity noise of the QS-SCL and mode-locked SCL is quantitatively compared. Furthermore, a special processing algorithm is ...

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    9. Efficient supercontinuum generation enabled by dispersion engineering in a dual-core waveguide

      Efficient supercontinuum generation enabled by dispersion engineering in a dual-core waveguide

      A compact dual-core waveguide is proposed for efficient supercontinuum generation, in which the use of Si-rich nitride and titanium dioxide provides a large enough index contrast for dispersion engineering. Strong anomalous group velocity dispersion is obtained over a wide bandwidth of 1860 nm which greatly reduces the dispersion length. The nonlinear length can also be significantly decreased due to high nonlinear Kerr index of Si-rich nitride. As a consequence, it could facilitate octave-spanning supercontinuum generation from 1160 to 2385 nm in a greatly reduced propagation distance, as short as 165μm . It is more than one order of magnitude shorter ...

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    10. A Step-Index Silicate Nonlinear Fiber With All Normal Flattened Dispersion for Coherent Supercontinuum

      A Step-Index Silicate Nonlinear Fiber With All Normal Flattened Dispersion for Coherent Supercontinuum

      A step-index silicate fiber with all normal flat dispersion was fabricated. Coherent supercontinuum (SC) spectrum spanning 1200 to 2000 nm was generated in a 5 cm silicate fiber pumped at 1560 nm. The numerical simulation result agreed with the experiment result. Also, highly coherent SC spectrum spanning from 1100 to 2100 nm with flatness <7 dB generated in the fiber with 57 kW pumping power according to simulation. The step-index silicate fiber is not only easy to prepare but also a promising candidate to achieve all-fiber structure for coherent SC.

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    11. Numerical investigation on coherent mid-infrared supercontinuum generation in chalcogenide PCFs with near zero flattened all-normal dispersion profiles

      Numerical investigation on coherent mid-infrared supercontinuum generation in chalcogenide PCFs with near zero flattened all-normal dispersion profiles

      We present a novel design of all-normal flat near zero dispersion chalcogenide photonics crystal fiber (PCF) for mid-infrared supercontinuum (SC) generation. The proposed PCF with a core made of As<sub>2</sub>Se<sub>3</sub> glass and uniform air holes in the cladding is selectively filled with As<sub>2</sub>S<sub>5</sub> glass. By carefully engineering the PCF with an all-normal flat near zero dispersion profile, the anomalous-dispersion soliton effects are reduced, enabling broadband highly coherent SC generation. We also investigate the impacts of the pulse parameters on the SC generation. Broadband SCs covering 1 ...

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    12. Highly coherent supercontinuum generation in CS2 infiltrated single-core optical fiber

      Highly coherent supercontinuum generation in CS2 infiltrated single-core optical fiber

      As is generally known, broad-band near-infrared Supercontinuum (SC) is significant for the applications such as pump-probe spectroscopy, nonlinear spectroscopy, frequency combs, or nonlinear optical parametric amplification. We present the first detailed demonstration of approximate near-infrared, octave-spanning SC generation in all-normal dispersion CS2 single-hole liquid core optical fiber (LCOF). By solving the generalized nonlinear Schrödinger equation, the SC at different parameters can be calculated. The influence of important parameters including but not limited to fiber core-diameter, pump wavelength, pump power, and pulse width, on the supercontinuum generation (SCG) of CS2 infiltrated LCOF can be analyzed for optimization of near-infrared SC ...

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    13. Generation and characterization of mid-infrared supercontinuum in polarization maintained ZBLAN fibers

      Generation and characterization of mid-infrared supercontinuum in polarization maintained ZBLAN fibers

      We present mid-infrared (MIR) supercontinuum generation in polarization-maintained ZBLAN fibers pumped by 2 µm femtosecond pulses from a Tm:YAP regenerative amplifier. A stable supercontinuum that spreads from 380 nm to 4 µm was generated by coupling only 0.5 µJ pulse energy into an elliptical core ZBLAN fiber. The supercontinuum was characterized using cross-correlation frequency-resolved optical gating (XFROG). The complex structure of the XFROG trace due to the pulse-to-pulse spectrum instability have been fixed by reducing the length of the applied fibers or improving the quality of the incident pulse spectrum

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    14. Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation

      Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation

      In this paper, we report the design and fabrication of a highly birefringent polarization-maintaining photonic crystal fiber (PM-PCF) made from chalcogenide glass, and its application to linearly-polarized supercontinuum (SC) generation in the mid-infrared region. The fiber was drawn using the casting method from As38Se62 glass which features a transmission window from 2 to 10 µm and a high nonlinear index of 1.13×10-17 m2 /W. It has a zero-dispersion wavelength around 4.5 µm and, at this wavelength, a large birefringence of 6×10-4 and consequently strong polarization maintaining properties are expected. Using this fiber, we experimentally demonstrate supercontinuum ...

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    15. EXALOS Introduces RGB Modules for Augmented Reality and Head-up Display Applications

      EXALOS Introduces RGB Modules for Augmented Reality and Head-up Display Applications

      Schlieren, Switzerland, May 6 th , 2019. EXALOS, the world’s leading developer of visible Superluminescent Light Emitting Diodes (SLEDs), has expanded its product porfolio with the introduction of a compact RGB SLED module that will enable the advancement of micro-display architectures for augmented reality (AR) and head-up displays (HUDs). The RGB module constitutes three SLED chips housed in a 14-pin butterfly package (20.8 mm x 1.7 mm) with a total output power of about 30 mW (~ 10 mW/color), which corresponds to a total luminous flux of 5 lm. The individual chips (635 nm (R), 510 nm (G ...

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      Mentions: Exalos Kevin Hsu
    16. Supercontinuum light source comprising microstructured optical fiber

      Supercontinuum light source comprising microstructured optical fiber

      The invention relates to a microstructured optical fiber for generating supercontinuum light upon feeding of pump light. The light can be incoherent light. The microstructured optical fiber has a first section and a second section, where the first and second sections have one or more different features. The invention also relates to a supercontinuum source comprising a microstructured optical fiber according to the invention.

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      Mentions: NKT Photonics
    17. Supercontinuum noise reduction by fiber undertapering

      Supercontinuum noise reduction by fiber undertapering

      We demonstrate that the Relative Intensity Noise (RIN) of a supercontinuum source can be significantly reduced using the new concept of undertapering, where the fiber is tapered to a diameter that is smaller than the diameter that gives the shortest blue edge, which is typically regarded as the optimum. We show that undertapering allows to control the second zero dispersion wavelength and use it as a soliton barrier to stop the redshifting solitons at a pre-defined wavelength, and thereby strongly reduce the RIN. We demonstrate how undertapering can reduce the spectrally averaged RIN in the optical coherence tomography bands, 500 ...

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    18. Development of a broadband superluminescent diode based on self-assembled InAs quantum dots and demonstration of high-axial-resolution optical coherence tomography imaging

      Development of a broadband superluminescent diode based on self-assembled InAs quantum dots and demonstration of high-axial-resolution optical coherence tomography imaging

      We developed a near-infrared (NIR) superluminescent diode (SLD) based on self-assembled InAs quantum dots (QDs) and demonstrated high-axial-resolution optical coherence tomography (OCT) imaging using this QD-based SLD (QD-SLD). The QD-SLD utilized InAs QDs with controlled emission wavelengths as a NIR broadband light emitter, and a tilted waveguide with segmented electrodes was prepared for edge-emitting broadband electroluminescence (EL) spanning approximately 1–1.3 μm. The bandwidth of the EL spectrum was increased up to 144 nm at a temperature of 25 °C controlled using a thermoelectric cooler. The inverse Fourier transform of the EL spectrum predicted a minimum resolution of 3 ...

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    19. Soliton microcomb based spectral domain optical coherence tomography

      Soliton microcomb based spectral domain optical coherence tomography

      Spectral domain optical coherence tomography (SD-OCT) has become a widely applied minimally invasive technique for bio-medical imaging[1–4], and industrial process control[5]. One of the most commonly used light source for SD-OCT is based on superluminescent diodes (SLD), which provide a low-noise broadband coverage.[6] Recent advances have allowed creating photonic integrated chipscale frequency combs, that provide an attractive alternative illumination scheme for SD-OCT. Yet to date, the use of such soliton micro-combs in OCT has not been demonstrated or considered. Here we explore the use of soliton microcombs in spectral domain OCT. By using photonic chipscale Si3N4 ...

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    20. EXALOS releases NEW Ultrabroadband Superluminescent Light Emitting Diodes for Medical Imaging and Sensor applications

      EXALOS releases NEW Ultrabroadband Superluminescent Light Emitting Diodes for Medical Imaging and Sensor applications

      EXALOS has expanded its portfolio of Superluminescent Light Emitting Diodes (SLEDs) by introducing our new near-IR Combi-SLED modules where multiple SLED devices are spectrally combined to provide an ultra-broadband spectrum. The light output of the SLEDs are collimated using micro-optical collimation lenses, spectrally combined and colinearly aligned through free-space dielectric edge filters and focused into a single-mode fiber. The Combi-SLEDs are especially suited for medical imaging applications such as ultra-high-resolution Optical Coherence Tomography (UHR-OCT) and Fiber Optic Sensor applications thanks to their high output power. large spectral bandwidth and short coherence length. The first product release of such a Combi-SLED ...

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      Mentions: Exalos Kevin Hsu
    21. EXALOS Introduces RGB Modules for Augmented Reality and Head-up Display Applications

      EXALOS Introduces RGB Modules for Augmented Reality and Head-up Display Applications

      EXALOS, the world’s leading developer of visible Superluminescent Light Emitting Diodes (SLEDs), has expanded its product porfolio with the introduction of a compact RGB SLED module that will enable the advancement of micro-display architectures for augmented reality (AR) and head-up displays (HUDs). The RGB module constitutes three SLED chips housed in a 14-pin butterfly package (20.8 mm x 1.7 mm) with a total output power of about 30 mW (~ 10 mW/color), which corresponds to a total luminous flux of 5 lm. The individual chips (635 nm (R), 510 nm (G), and 450 nm (B)) are each ...

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      Mentions: Exalos Kevin Hsu
    22. Noise of supercontinuum sources in spectral domain optical coherence tomography

      Noise of supercontinuum sources in spectral domain optical coherence tomography

      In this paper, we investigate the effect of pulse-to-pulse fluctuations of supercontinuum sources on the noise in spectral domain optical coherence tomography (OCT) images. The commonly quoted theoretical expression for the OCT noise is derived for a thermal light source, which is not suitable if a supercontinuum light source is used. We therefore propose a new, measurement-based OCT noise model that predicts the noise without any assumptions on the type of light source. We show that the predicted noise values are in excellent agreement with the measured values. The spectral correlation evaluated for the photodetected signal when using a supercontinuum ...

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    23. New U of A laser technology shows promise to treat leading causes of blindness

      New U of A laser technology shows promise to treat leading causes of blindness

      AMD damages the retina of the eye and is the leading cause of blindness globally. Glaucoma is characterized by an increase of pressure within the eye that damages the optic nerve, eventually leading to blindness. It’s projected that by 2020, more than 196 million people will be affected by AMD and 76 million people will be affected by glaucoma. The platform Katchinskiy is developing combines femtosecond lasers with optical coherence tomography, a technology for evaluating conditions of the retina, and scanning laser ophthalmoscopy, a method for creating diagnostic images of the retina that enables a high degree of spatial ...

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    24. Supercontinuum in the practice of Optical Coherence Tomography with emphasis on noise effects (Thesis)

      Supercontinuum in the practice of Optical Coherence Tomography with emphasis on noise effects (Thesis)

      Optical Coherence Tomography (OCT) is an imaging modality which has proven, since the early 1990s, its incredible potential. Nowadays, numerous fields of medical investigation, such as Ophthalmology, Dermatology or Cardiovascular imaging, would not be the same without the diagnostic tools bring by OCT. This tremendous development has been supported by industry support through improvement of dedicated components such as lasers, cameras and optics. A great example of this development is the evolution of Supercontinuum (SC) sources. Due to the extremely broad spectrum cover by SC sources, their high power density and high spatial coherence, it seems obvious to use them ...

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