1. Articles in category: Tunable Sources

    1-24 of 421 1 2 3 4 ... 16 17 18 »
    1. Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural ...

      Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural ...

      Swept source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure. However, applications requiring wide fields of view (FOV), rapid imaging, and higher resolutions have been challenging because multi-MHz axial scan (A-scan) rates are needed. We describe a microelectromechanical systems vertical cavity surface-emitting laser (MEMS-VCSEL) SS-OCT technology for A-scan rates of 2.4 and 3.0 MHz. Sweep to sweep calibration and resampling are performed using dual channel acquisition of the OCT signal and a Mach Zehnder interferometer signal, overcoming inherent optical clock limitations and enabling higher performance. We demonstrate ultrahigh speed structural SS-OCT and OCT angiography (OCTA) imaging ...

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    2. Tunable VCSEL polarization control through dissimilar die bonding

      Tunable VCSEL polarization control through dissimilar die bonding

      A design and method for introducing asymmetric crystal strain to control polarization in a tunable VCSEL, either optically or electrically pumped. The invention is especially relevant to wafer- or die-bonded tunable VCSELs. Then, mechanical stress is applied to the half VCSEL device by asymmetric arrangement of metal bond pads.

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    3. Optically pumped tunable VCSEL employing geometric isolation

      Optically pumped tunable VCSEL employing geometric isolation

      An optically pumped tunable VCSEL swept source module has a VCSEL and a pump, which produces light to pump the VSCEL, wherein the pump is geometrically isolated from the VCSEL. In different embodiments, the pump is geometrically isolated by defocusing light from the pump in front of the VCSEL, behind the VCSEL, and/or by coupling the light from the pump at an angle with respect to the VCSEL. In the last case, angle is usually less than 88 degrees. There are further strategies for attacking pump noise problems. Pump feedback can be reduced through (1) Faraday isolation and (2 ...

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    4. Introducing the fastest VCSEL Swept Source to market

      Introducing the fastest VCSEL Swept Source to market

      ast 3D imaging with MHz VCSEL Swept Source OCTLIGHT is extending the Caliper product family with the new Caliper-HERO which is the fastest available scalable solution for 3D OCT imaging on the market. It is based on the truly single-mode wavelength tuning VCSEL technology. The patented Highly Efficient Resonant Oscillator (HERO TM ) achieves blazing MHz speeds and single channel acquisition. This pushes the performance that can be achieved in e.g. blood flow imaging, wider field of view imaging and real-time 3D imaging for robotic surgery with a clear path for translation into commercial product benefitting ophthalmologists and patients. Caliper-HERO ...

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    5. 1.1 μm waveband tunable laser using emission-wavelength-controlled InAs quantum dots for swept-source optical coherence tomography applications

      1.1 μm waveband tunable laser using emission-wavelength-controlled InAs quantum dots for swept-source optical coherence tomography applications

      In this study, an optical gain chip using emission-wavelength-controlled self-assembled InAs quantum dots (QDs) was developed for swept-source optical coherence tomography (SS-OCT) applications. The optical characterizations indicated that the QDs emission wavelength and optical gain spectra were controlled in the 1.1 μ m waveband by optimizing the QDs growth conditions. This waveband is useful for obtaining a large imaging depth of OCT because of an optimal balance between absorption and scattering in biological samples. In addition, continuous tunable lasing in the waveband was achieved by introducing the QD-based gain chip into a grating-coupled external cavity. This tunable laser was introduced ...

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    6. Method for preserving the synchronism of a Fourier Domain Mode Locked (FDML) laser

      Method for preserving the synchronism of a Fourier Domain Mode Locked (FDML) laser

      The invention relates to a method for maintaining the synchronism of a Fourier Domain Mode Locked (FDML) laser, the FDML laser comprising at least one dispersion-compensated resonator with at least one variably wavelength-selective optical filter, the laser light circulating in the resonator at a circulation frequency, and the wavelength selectivity of the filter being repeatedly modified at a syntonising rate, the FDML laser being synchronous when the syntonising rate is an integral multiple of the circulation frequency. Said method is characterised by the following steps: a) at least a portion of the laser light is coupled out of the resonator ...

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      Mentions: Optores
    7. Multi-cavity wavelength tunable laser device

      Multi-cavity wavelength tunable laser device

      A wavelength tunable laser device includes a gain element that provides optical gain. A laser cavity includes at least two cavities, wherein each of the at least two cavities has a different optical cavity length. At least two optical modulators are positioned in the laser cavity, wherein the at least two optical modulators are driven with waveforms so as to tune a wavelength of the wavelength tunable laser device.

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    8. VIS-OCT needs stable, versatile light sources

      VIS-OCT needs stable, versatile light sources

      Optical coherence tomography (OCT) is the gold standard for noninvasive retinal imaging, enabling ophthalmologists to diagnose and treat multiple ocular diseases. Compared to traditional OCT, which uses near-infrared (NIR) wavelengths of light, visible-light OCT (VIS-OCT) offers superior spatial resolution and novel functional imaging capabilities. VIS-OCT provides the most accurate means for measuring retinal oxygen saturation, a key biomarker for understanding changes in tissue metabolism associated with the pathology of various retinal diseases. Traditional OCT has dominated ophthalmic diagnostics for the past 30 years. Thanks to investment in and development of key OCT components, there is an opportunity to accelerate adoption ...

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    9. PhD Position Available in Lübeck: Development of an Ultra-Wideband FDML-Laser

      PhD Position Available in Lübeck: Development of an Ultra-Wideband FDML-Laser

      We offer a three year PhD student position for an Early Stage Researcher (ESR) on laser development in biomedical optics. The position is part of a Marie Skłodowska-Curie Innovative Training Network (ITN) within the EU Horizon 2020 Framework Programme. It will be within the project NETLAS (https://cordis.europa.eu/project/id/860807), which focuses on innovative solutions for fast, narrow linewidth, phase stable and wide tuning bandwidth swept sources as well as on their application in biomedical optics - especially for optical coherence tomography (OCT). 

      The position is in the group of Robert Huber at the University of Lübeck ...

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    10. Flexible A-scan rate MHz-OCT: efficient computational downscaling by coherent averaging

      Flexible A-scan rate MHz-OCT: efficient computational downscaling by coherent averaging

      In order to realize adjustable A-scan rates of fast optical coherence tomography (OCT) systems, we investigate averaging of OCT image data acquired with a MHz-OCT system based on a Fourier Domain Mode Locked (FDML) laser. Increased system sensitivity and image quality can be achieved with the same system at the cost of lower imaging speed. Effectively, the A-scan rate can be reduced in software by a freely selectable factor. We demonstrate a detailed technical layout of the strategies necessary to achieve efficient coherent averaging. Since there are many new challenges specific to coherent averaging in swept source MHz-OCT, we analyze ...

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    11. Linear-in-wavenumber actively-mode-locked wavelength-swept laser

      Linear-in-wavenumber actively-mode-locked wavelength-swept laser

      We report on an akinetic actively-mode-locked wavelength-swept laser (ASL) with a sweep that is highly linear in wavenumber. By tailoring the drive waveform of the intracavity modulator, the wavenumber sweep was further linearized to enable high fidelity frequency-domain interferometric ranging without resampling of the acquired data. Used for catheter-based optical coherence tomography, the ASL showed comparable imaging performance to a state-of-the-art polygon-based wavelength-swept source at a matching sweep rate of 103.6 kHz, a duty cycle of 95%, and a bandwidth of 100 nm, centered at 1330 nm.

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    12. Frequency-doubled FDML-MOPA laser in the visible

      Frequency-doubled FDML-MOPA laser in the visible

      Wavelength-swept lasers enable high-speed measurements in absorption spectroscopy, Raman spectroscopy, nonlinear Raman hyperspectral microscopy, rapid confocal microscopy, short impulse generation, and most importantly for high-speed optical coherence tomography, with speeds up to video-rate volumetric imaging. Recently, we introduced a pulsed wavelength-swept laser based on the Fourier domain mode-locked (FDML) laser principle combined with a master-oscillator power amplifier (MOPA) architecture. The high peak powers reached with this laser enabled rapid two-photon microscopy and two-photon fluorescence lifetime microscopy and high-speed light detection and ranging measurements. Here, we present the extension of this laser into the visible wavelength range by frequency doubling the ...

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    13. Stepped frequency comb generation based on electro-optic phase-code mode-locking for moderate-speed circular-ranging OCT

      Stepped frequency comb generation based on electro-optic phase-code mode-locking for moderate-speed circular-ranging OCT

      Circular-ranging (CR) optical coherence tomography (OCT) uses frequency comb sources to improve long-range imaging. While the initial development of CR-OCT focused on extremely high-speed imaging (i.e., operation at A-line rates of several to tens of MHz), there are many applications and imaging strategies for which more moderate speeds are preferred. However, we lack suitable frequency comb sources to enable moderate speed CR-OCT imaging. Here, we describe a novel phase-code mode-locking (PCML) laser architecture that can be operated from the kilohertz to megahertz range, while also offering novel features such as dynamic re-configurability and simplified linear-in-time frequency stepping. We demonstrate ...

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    14. 9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking

      9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking

      In optical coherence tomography (OCT), high-speed systems based at 1300 nm are among the most broadly used. Here, we present 9.4 MHz A-line rate OCT system at 1300 nm. A wavelength-swept laser based on stretched-pulse active mode locking (SPML) provides a continuous and linear-in-wavenumber sweep from 1240 nm to 1340 nm, and the OCT system using this light source provides a sensitivity of 98 dB and a single-sided 6-dB roll-off depth of 2.5 mm. We present new capabilities of the 9.4 MHz SPML-OCT system in three microscopy applications. First, we demonstrate high quality OCTA imaging at a ...

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    15. PhD position on tunable lasers for optical coherence tomography at the University of Kent

      PhD position on tunable lasers for optical coherence tomography at the University of Kent

      We are recruiting for a PhD Studentship in the fields of Optics and Laser Physics, with emphasis on optical coherence tomography for a period of 36 months starting up to 31 January 2021, within the Applied Optics Group, School of Physical Sciences. This is supported by the Marie Curie Innovative Training Network scheme, 860807, EU funded, jointly organised with 14 other universities, companies and hospitals in Europe. You will spend time at the University of Kent and at the other beneficiaries or associated partners. Supervision will be provided in an European setting where specialized and complementary training will be provided ...

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    16. Spectrally shaped tunable short-cavity laser

      Spectrally shaped tunable short-cavity laser

      A tunable source includes a short-cavity laser optimized for performance and reliability in SSOCT imaging systems, spectroscopic detection systems, and other types of detection and sensing systems. The short cavity laser has a large free spectral range cavity, fast tuning response and single transverse, longitudinal and polarization mode operation, and includes embodiments for fast and wide tuning, and optimized spectral shaping. Disclosed are both electrical and optical pumping in a MEMS-VCSEL geometry with mirror and gain regions optimized for wide tuning, high output power, and a variety of preferred wavelength ranges; and a semiconductor optical amplifier, combined with the short-cavity ...

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    17. Highly Stable All-Fiber-Ring Short-Cavity Continuously Tuned Swept Source

      Highly Stable All-Fiber-Ring Short-Cavity Continuously Tuned Swept Source

      In this study, we present a swept source that can intelligently control its sweeping speed while satisfying the commercial stability and miniaturization standards. The source’s central wavelength of the output spectrum is 1300 nm and spectral width is greater than 100 nm. Meanwhile, the scan frequency can be adjusted to range from 20 to 100 kHz, and the stability degree of the optical capacity is less than 0.34%. Additionally, this study establishes a numerical model for the swept-source optical coherence tomography (SS–OCT) system and introduces a numerical simulation of the signal produced during the OCT imaging process ...

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    18. Resolving absolute depth in circular-ranging optical coherence tomography by using a degenerate frequency comb

      Resolving absolute depth in circular-ranging optical coherence tomography by using a degenerate frequency comb

      In Fourier-domain optical coherence tomography, an interference signal is generated that spans an RF bandwidth proportional to the product of three parameters: the imaging range, the imaging speed, and the inverse of the axial resolution. Circular-ranging optical coherence tomography (CR-OCT) architectures were introduced to ease long-range imaging by decoupling the imaging range from the signal RF bandwidth. As a consequence, present CR-OCT systems resolve the relative, but not the absolute, depth location of the scatterers. We introduce here a modified implementation of CR-OCT that uses a degenerate frequency comb source that allows recovery of absolute depth information while only minimally ...

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    19. 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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    20. Multimodality Imaging Approach for Combined Central Retinal Vein and Artery Occlusion: The Role of Optical Coherence Tomography Angiography

      Multimodality Imaging Approach for Combined Central Retinal Vein and Artery Occlusion: The Role of Optical Coherence Tomography Angiography

      Combined central retinal artery and vein occlusion is an uncommon vascular pathology that can cause severe and permanent visual impairment. Optical coherence tomography angiography (OCTA) is a newly available, noninvasive imaging technique that can potentially improve understanding of the structural and vascular implications and prognosis of this infrequent pathology. The present report describes the principal clinical findings in a case of combined central retinal artery and vein occlusion, as detected by the different imaging modalities available in a tertiary referral hospital. OCTA wide-field montage images identified an extensive area of nonperfusion on the macula with involvement of the entire retina ...

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    21. Surface emitting laser, information obtaining apparatus, and imaging apparatus

      Surface emitting laser, information obtaining apparatus, and imaging apparatus

      The present invention provides a surface emitting laser the wavelength-tunable band of which is wide. The wavelength-tunable surface emitting laser includes a first reflector (101), an active layer (103) disposed on the first reflector (101), a beam portion (110) disposed over the active layer (103) with an air gap therebetween, and a second reflector (120) disposed on the beam portion (110). The second reflector (120) has a distributed Bragg reflector consisting of a stack of dielectric layers. The beam portion (110) has a distributed Bragg reflector consisting of a stack of conductive semiconductor layers.

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    22. Method for signal processing in optical coherence tomography by means of a tunable light source

      Method for signal processing in optical coherence tomography by means of a tunable light source

      The invention relates to a method for signal processing in optical coherence tomography by means of a tunable light source (swept source), comprising the following steps: tuning the light source and sensing a signal intensity of the light source in linear dependence on the respective wave number (k) of the tunable light source and producing a signal intensity distribution in dependence on k; applying a window function to the sensed signal intensity distribution and producing a weighted signal intensity distribution; and applying a fast Fourier transform (FFT) to the weighted signal intensity distribution; and characterized in that, in the tuning ...

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    23. Thorlabs Extends MEMS-VCSEL Swept-Wavelength Laser Source Offering to Include 1060 nm

      Thorlabs Extends MEMS-VCSEL Swept-Wavelength Laser Source Offering to Include 1060 nm

      Thorlabs announced today that it has released next-generation versions of its MEMS-VCSEL Swept-Wavelength Laser Sources. The new SL10 series, centered at 1060 nm, complements the already well-established SL13 series at 1300 nm and is available with four different sweep rates ranging from 60 kHz to 400 kHz. Based on a patented microelectromechanical system (MEMS) tunable vertical cavity surface emitting laser (VCSEL), these light sources feature a record-breaking coherence length of over 100 mm and include an active power control that maintains constant output power over the lifetime of the laser. All drive electronics and trigger signals needed to seamlessly integrate ...

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      Mentions: Thorlabs
    1-24 of 421 1 2 3 4 ... 16 17 18 »
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