1. Articles in category: Tunable Sources

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    1. Voltage Noise and Jitter Analysis for Swept Source Optical Coherence Tomography using KTa1-xNbxO3 Deflector

      Voltage Noise and Jitter Analysis for Swept Source Optical Coherence Tomography using KTa1-xNbxO3 Deflector

      This paper describes voltage noise and jitter analysis for the depth deviation of a point spread function in a swept source optical coherence tomography system using a KTa1-xNbxO3 deflector. An interference waveform with voltage noise and jitter was simulated according to a previous report. Typical values for the voltage noise ΔVTYP and jitter ΔtTYPwere also obtained from a previous report and experiment. It was determined that the depth deviation is limited by the ΔtTYP of the system. Therefore, the quality of the tomographic image can be efficiently improved by reducing jitter.

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      Mentions: NTT
    2. SS-OCT enables increased speed, deeper penetration, but steeper cost

      SS-OCT enables increased speed, deeper penetration, but steeper cost

      Swept source OCT has many benefits over spectral domain OCT, but its biggest obstacle today is cost, according to Jay S. Du k er at the American Academy of Optometry annual meeting. SS-OCT is a form of fourier domain detection, which is how the echo time delay is calculated in the device, he said. The SS light source is a tunable laser that rapidly changes the wavelength, which is very expensive, he added. The reflections of depth are detected with photodetectors, not with a camera as with SD-OCT. The longer wavelength of SS-OCT images (1,000 nm to 1,300 ...

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    3. Spectrally tunable illumination system based on acousto-optic diffraction of light

      Spectrally tunable illumination system based on acousto-optic diffraction of light

      Spectrally tunable illumination is widely used for spectral imaging, spectroscopy, spectral-domain optical coherence tomography and other applications. Most of swept-wavelength light sources are based on mechanical change of narrow-band filters or on a supercontinuum laser coupled with a tunable filter. Such commercially available sources suffer either from a limited number of spectral channels or from a spatial noise caused by parasitic interferences. Here, we describe an alternative solution, which is free from the mentioned disadvantages and provides speckle-free uniform illumination. It is based on acousto-optic (AO) diffraction of a wide-band light. AO tunable filters (AOTFs) are fully software-controlled solid-state devices ...

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    4. Extended coherence length and depth ranging using a Fourier domain mode-locked frequency comb and circular interferometric ranging

      Extended coherence length and depth ranging using a Fourier domain mode-locked frequency comb and circular interferometric ranging

      Fourier domain mode-locking (FDML) has been a popular laser design for high speed optical frequency domain imaging (OFDI) but achieving long coherence lengths, and therefore imaging range, has been challenging. The narrow instantaneous linewidth of a frequency comb (FC) FDML laser could provide an attractive platform for high speed as well as long range OFDI. Unfortunately, aliasing artifacts arising from signals beyond the principle measurement depth of the free spectral range have prohibited the use of a FC FDML for imaging so far. To make the enhanced coherence length of FC FDML laser available, methods to manage such artifacts are ...

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    5. OCT system with bonded MEMS tunable mirror VCSEL swept source

      OCT system with bonded MEMS tunable mirror VCSEL swept source

      A microelectromechanical systems (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) in which the MEMS mirror is bonded to the active region. This allows for a separate electrostatic cavity that is outside the laser's optical resonant cavity. Moreover, the use of this cavity configuration allows the MEMS mirror to be tuned by pulling the mirror away from the active region. This reduces the risk of snap down. Moreover, since the MEMS mirror is now bonded to the active region, much wider latitude is available in the technologies that are used to fabricate the MEMS mirror. This is preferably deployed as a ...

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    6. Thorlabs Releases New MEMS‐VCSEL Swept‐Wavelength Laser Sources

      Thorlabs Releases New MEMS‐VCSEL Swept‐Wavelength Laser Sources

      Thorlabs announced today that it has released next‐generation versions of its 1300 nm MEMS‐VCSEL Swept‐Wavelength Laser Sources. With a record‐breaking coherence length of over 100 mm and sweep rates of either 100 kHz or 200 kHz, the SL131090 and SL132120 are the only commercially available MEMS‐VCSEL laser sources on the market. Based on a patented microelectromechanical system (MEMS) tunable vertical cavity surface emitting laser (VCSEL), these light sources 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 these ...

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      Mentions: Thorlabs
    7. Ultra low noise Fourier domain mode locked laser for high quality megahertz optical coherence tomography

      Ultra low noise Fourier domain mode locked laser for high quality megahertz optical coherence tomography

      We investigate the origin of high frequency noise in Fourier domain mode locked (FDML) lasers and present an extremely well dispersion compensated setup which virtually eliminates intensity noise and dramatically improves coherence properties. We show optical coherence tomography (OCT) imaging at 3.2 MHz A-scan rate and demonstrate the positive impact of the described improvements on the image quality. Especially in highly scattering samples, at specular reflections and for strong signals at large depth, the noise in optical coherence tomography images is significantly reduced. We also describe a simple model that suggests a passive physical stabilizing mechanism that leads to ...

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    8. Axsun Technologies Announces Breakthrough Tunable VCSEL Platform for Optical Coherence Tomography (OCT) Imaging

      Axsun Technologies Announces Breakthrough Tunable VCSEL Platform for Optical Coherence Tomography (OCT) Imaging

      Axsun Technologies, Inc., a leading developer and supplier of MEMSbased optical engines for medical imaging, industrial spectroscopy, and optical telecommunications, today announced the development of a novel Tunable Vertical Cavity Surface Emitting Laser (Tunable VCSEL) platform for OCT imaging applications. Raising the bar on OCT imaging performance, Axsun’s new Tunable VCSEL platform leverages the company’s core strengths of high performance optical integration and cost-effective volume manufacturing. By integrating all the major tunable VCSEL components into a single compact butterfly package, the Axsun tunable VCSEL enables higher performance and flexibility, reliability and scalability with low power consumption. “While our ...

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    9. Axsun Technologies Reaches Shipment Milestone of 15,000 Swept Lasers for Optical Coherence Tomography (OCT) Imaging

      Axsun Technologies Reaches Shipment Milestone of 15,000 Swept Lasers for Optical Coherence Tomography (OCT) Imaging

      Axsun Technologies, Inc., the leading manufacturer of Swept Source Optical Coherence Tomography (SSOCT) engines, today announced that the company has shipped over 15,000 swept lasers for OCT imaging applications. “Axsun’s lasers for OCT imaging enable the highest performance systems in ophthalmology, vascular and other medical and industrial imaging applications,” explained Jonathan Hartmann, CEO of Axsun. “This significant milestone in our company’s history is a testament to Axsun’s technology leadership, the scalability of our manufacturing platform, and our incredible team. It is also an exciting milestone for our customers and the patients they serve with this leading ...

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    10. Surface emitting laser, laser array, light source device, information acquisition device, and optical coherence tomography apparatus

      Surface emitting laser, laser array, light source device, information acquisition device, and optical coherence tomography apparatus

      Provided is a surface emitting laser that is to be excited by an external light source and in which a light-emitting position is defined. A surface emitting laser includes a pair of reflecting mirrors (11, 15) and an active layer (13) that is arranged between the pair of reflecting mirrors (11, 15) and that is to be excited by light that is radiated from an external light source. A gap is formed between the active layer and one of the pair of reflecting mirrors (15), the oscillation wavelength of the surface emitting laser is changed, and a defining structure (20 ...

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    11. Spatio-temporally incremental fiber swept source

      Spatio-temporally incremental fiber swept source

      A spatio-temporally incremental fiber sweep source includes a laser light pulse generator for generating light pulses and a fiber array of individual optical fibers. The fiber array has an input end and an output end, with the fibers at the input end receiving the light pulses substantially simultaneously. The optical fibers at the output end are arranged in a raster scan pattern, e.g., a square pattern, wherein the optical delay in each fiber is greater than the previous one in the scan pattern direction. As a result light exits the array in a completely optical two dimensional raster scan ...

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    12. OCTLIGHT Closes Investment Round on Path to Commercialize OCT Swept Source

      OCTLIGHT Closes Investment Round on Path to Commercialize OCT Swept Source

      OCTLIGHT secures funding years ahead upon successful reaching key milestone OCTLIGHT ApS announces that it has closed an investment round following the successful completion of milestones towards commercializing OCT swept source modules. The funding, which was closed according to plan, will cover the activities of OCTLIGHT over the coming years, focused on development of OCT swept source modules for Ophthalmology as the primary market. Wavelength tuning range doubled to 52 nm showing path towards goal of 100 nm OCTLIGHT has achieved significant milestones towards bringing OCT swept source modules to market. The development of the core VCSEL technology continues, with ...

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    13. Apparatus and methods for one or more wavelength swept lasers and the detection of signals thereof

      Apparatus and methods for one or more wavelength swept lasers and the detection of signals thereof

      An optical instrument including at least a first and second wavelength swept vertical cavity laser (VCL) sources. The wavelength sweeping ranges spanned by the first and second VCL sources may differ with a region of spectral overlap. The first and second VCL sources may be operable under different modes of operation, wherein the modes of operation differ in at least one of: sweep repetition rate, sweep wavelength range, sweep center wavelength, and sweep trajectory. A VCL source may also exhibit sweep-to-sweep variation. Apparatus and methods are described for aligning sample signal data from the first VCL and sample signal data ...

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    14. Unfolding displacement measurement method for the aliasing interferometer signal of a wavelength-comb-swept laser

      Unfolding displacement measurement method for the aliasing interferometer signal of a wavelength-comb-swept laser

      We demonstrate an unfolding displacement measurement method to overcome the aliasing problem of wavelength-comb-swept laser (WCSL). Compared to the conventional wavelength-swept laser (WSL), the WCSL exhibits an extended coherence length, owing to the narrowing spectral linewidth of the etalon filter. However, the aliasing interference signal induces an unexpected back-bounced phenomenon during displacement measurement because of the discretely distributed comb-like periodic spectra of the etalon filter. By using the dual-reference interferometry method, the back-bounced displacement measurement can be successfully unfolded to extend the measurement range by two times. In addition, we demonstrate a longer-range surface profiling image over 18 mm within ...

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    15. Widely tunable short cavity laser

      Widely 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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    16. High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates

      High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates

      We present a new 1060 nm Fourier domain mode locked laser (FDML laser) with a record 143 nm sweep bandwidth at 2∙ 417 kHz = 834 kHz and 120 nm at 1.67 MHz, respectively. We show that not only the bandwidth alone, but also the shape of the spectrum is critical for the resulting axial resolution, because of the specific wavelength-dependent absorption of the vitreous. The theoretical limit of our setup lies at 5.9 µm axial resolution. In vivo MHz-OCT imaging of human retina is performed and the image quality is compared to the previous results acquired with 70 ...

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    17. Direct experimental measurement of single-mode and mode-hopping dynamics in frequency swept lasers

      Direct experimental measurement of single-mode and mode-hopping dynamics in frequency swept lasers

      A time-resolved study is presented of the single-mode and mode-switching dynamics observed in swept source vertical cavity surfing emitting lasers and swept wavelength short external cavity lasers. A self-delayed interferometric technique is used to experimentally measure the phase and intensity of these frequency swept lasers, allowing direct examination of the modal dynamics. Visualisation of the instantaneous optical spectrum reveals mode-hop free single mode lasing in the case of the vertical cavity laser, with a tuning rate of 6.3 GHz/ns. More complex mode-switching behaviour occurs in the external cavity laser, with the mode-hopping dynamics found to be dominated by ...

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    18. Swept source OCT system and method with phase-locked detection

      Swept source OCT system and method with phase-locked detection

      A swept source OCT system and related method are disclosed. The system comprises a control device for operating a tunable light source in response to an electronic sweep control signal such that the tunable light source carries out wave length sweeps with a repetition rate f.sub.sweep, which depends on the frequency of the sweep control signal. The system further comprises a detection device for the time-resolved detection of an interference signal from a sample beam and a reference beam with the help of a detection cycle signal. The sweep control signal and the detection cycle signal are phase-locked ...

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    19. Widely tunable swept source

      Widely tunable swept source

      A high-speed, single-mode, high power, reliable and manufacturable wavelength-tunable light source operative to emit wavelength tunable radiation over a wavelength range contained in a wavelength span between about 950 nm and about 1150 nm, including a vertical cavity laser (VCL), the VCL having a gain region with at least one compressively strained quantum well containing Indium, Gallium, and Arsenic.

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    20. Eckhaus Instability in the Fourier-Domain Mode Locked Fiber Laser Cavity

      Eckhaus Instability in the Fourier-Domain Mode Locked Fiber Laser Cavity

      High frequency fluctuation in the optical signal generated in Fourier-Domain Mode Locked fiber laser (FDML-FL), which is the major problem and degrades the laser performance, is not yet fully analyzed or studied. The basic theory which is causing this high frequency fluctuation is required to clearly understand its dynamics and to control it for various applications. In this letter, by analyzing the signal and system dynamics of FDML-FL, we theoretically demonstrate that the high frequency fluctuation is induced by the intrinsic instability of frequency offset of the signal in cavity with nonlinear gain and spectral filter. Unlike the instabilities observed ...

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    21. Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      The rapid advance in swept-source optical coherence tomography (SS-OCT) technology has enabled exciting new applications in elastography, angiography, and vibrometry, where both high temporal resolution and phase stability are highly sought-after. In this paper, we present a 200 kHz SS-OCT system centered at 1321 nm by using an electro-optically tuned swept source. The proposed system’s performance was fully characterized, and it possesses superior phase stability (0.0012% scanning variability and <1 ns timing jitter) that is promising for many phase-sensitive imaging applications. Biological experiments were demonstrated within ex vivo human tracheobronchial ciliated epithelium where both the ciliary motion and ...

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    22. Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      The rapid advance in swept-source optical coherence tomography (SS-OCT) technology has enabled exciting new applications in elastography, angiography, and vibrometry, where both high temporal resolution and phase stability are highly sought-after. In this paper, we present a 200 kHz SS-OCT system centered at 1321 nm by using an electro-optically tuned swept source. The proposed system’s performance was fully characterized, and it possesses superior phase stability (0.0012% scanning variability and <1 ns timing jitter) that is promising for many phase-sensitive imaging applications. Biological experiments were demonstrated within ex vivo human tracheobronchial ciliated epithelium where both the ciliary motion and ...

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    23. Downhole sensing via swept source lasers

      Downhole sensing via swept source lasers

      Systems and methods for performing downhole analysis within a well bore employ a swept source laser that can be sent downhole to generate high resolution images of the well bore. Various embodiments can also determine other physical properties of a below ground structure. The swept source lasers can create images using low-coherence interferometry or optical coherence tomography. Systems and methods may also be used to determine fluid flow rates towards the sensor at discrete points, such as individual perforations, by measuring the Doppler effect on the light back-scattered from the fluid. Fluid flow information could also be extracted by measuring ...

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    24. Broadband wavelength-swept light source system and apparatus employing the same

      Broadband wavelength-swept light source system and apparatus employing the same

      A light source system includes: a plurality of gain mediums configured to output a corresponding plurality of lights having different center wavelengths from each other; a first light source part configured to connect the plurality of gain mediums to each other in parallel and emit the plurality of lights; a wavelength-swept filter unit configured to sweep wavelengths of the plurality of lights output by the plurality of gain mediums and compensate for spectroscopic optical paths of the plurality of lights; a second light source part configured to connect the first light source part to the wavelength-swept filter unit in series ...

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      Mentions: Samsung
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