1. Articles in category: Tunable Sources

    1-24 of 455 1 2 3 4 ... 17 18 19 »
    1. Electro-optically tunable single-frequency lasing from neodymium-doped lithium niobate microresonators

      Electro-optically tunable single-frequency lasing from neodymium-doped lithium niobate microresonators

      Tunable light sources are a key enabling technology for many applications such as ranging, spectroscopy, optical coherence tomography, digital imaging and interferometry. For miniaturized laser devices, whispering gallery resonator lasers are a well-suited platform, offering low thresholds and small linewidths, however, many realizations suffer from the lack of reliable tuning. Rare-earth ion-doped lithium niobate offers a way to solve this issue. Here we present a single-frequency laser based on a neodymium-doped lithium niobate whispering gallery mode resonator that is tuned via the linear electro-optic effect. Using a special geometry, we suppress higher-order transverse modes and hence ensure single-mode operation. With ...

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    2. Highly coherent, flat, and broadband time-stretched swept source based on extra-cavity spectral shaping assisted by a booster semiconductor optical amplifier

      Highly coherent, flat, and broadband time-stretched swept source based on extra-cavity spectral shaping assisted by a booster semiconductor optical amplifier

      We demonstrate a flat broadband time-stretched swept source based on extra-cavity spectral shaping. By adjusting the polarization-dependent gain profile and driving current of the booster optical amplifier (BOA), extra-cavity spectral shaping is optimized to generate output with a 1-dB bandwidth of ∼100 nm, 3-dB bandwidth of ∼140 nm and output power of ∼21.4 mW. The short-term and long-term stabilities are characterized. The average cross correlation of 183,485 round trips is 0.9997 with a standard deviation of 2×10 −5 , indicating high single-shot spectral similarity and high coherence. The noise floor of relative spectral energy jitter is −141 ...

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    3. 400 Hz Volume Rate Swept-Source Optical Coherence Tomography at 1060 nm Using a KTN Deflector

      400 Hz Volume Rate Swept-Source Optical Coherence Tomography at 1060 nm Using a KTN Deflector

      In this Letter, a swept-source optical coherence tomography (SS-OCT) instrument employing an innovative scanning protocol for high-speed volumetric rate imaging is demonstrated. The optical source is a tunable laser based on a supercontinuum source pumped with femtosecond pulses, followed by a time-stretched delay fiber. The instrument is equipped with an ultra-fast lateral scanner, based on a KTN crystal, driven at 100 kHz. The letter proves the utility of combining an ultra-fast lateral scanner with an ultra-fast swept laser to provide A-scans at a repetition rate of 40 MHz and an unprecedented 3D-OCT volume acquisition rate of 400 Hz.

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    4. Dual-comb based time-stretch optical coherence tomography for large and segmental imaging depth

      Dual-comb based time-stretch optical coherence tomography for large and segmental imaging depth

      Optical coherence tomography based on time-stretch enables high frame rate and high-resolution imaging for the inertia-free wavelength-swept mechanism. The fundamental obstacle is still the acquisition bandwidth's restriction on imaging depth. By introducing dual-comb with slightly different repetition rates, the induced Vernier effect is found to be capable of relieving the problem. In our work, a dual-comb based time-stretch optical coherence tomography is proposed and experimentally demonstrated, achieving a 1.5-m imaging depth and 200-kHz A-scan rate. Moreover, about a 33.4-µm resolution and 25-µm accuracy are achieved. In addition, by adjusting the frequency detuning of the dual-comb ...

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    5. Optical Interference Measurement using High-Coherence Wavelength Swept Light Sources

      Optical Interference Measurement using High-Coherence Wavelength Swept Light Sources

      Conventional contact measurement is replacing product shape inspection by non-contact optical measurement as part of the evolution of “smart factories”. Optical measurement includes various non-contact and non-destructive optical interferometry methods. Conventional methods feature accuracies ranging from nm to µm-order levels, but measurement distances are short, and high measurement accuracy is difficult to achieve due to meter-level measurement distances for targets with large surface areas. Our Wavelength swept light source with high coherence length supports accurate measurement over distances of several meters. This article explains the basic principles of OFDR as a typical optical interferometry measurement method and discusses the results ...

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    6. Praevium Research Inc Receives NIH Grant for Next generation MEMS-VCSEL technology for ultra-low-cost dental and periodontal swept source optical coherence tomography imaging

      Praevium Research Inc Receives NIH Grant for Next generation MEMS-VCSEL technology for ultra-low-cost dental and periodontal swept source optical coherence tomography imaging

      Praevium Research Inc Received a 2022 NIH Grant for $275,001 for Next generation MEMS-VCSEL technology for ultra-low-cost dental and periodontal swept source optical coherence tomography imaging. The principal investigator is Vijaysekhar Jayaraman. Below is a summary of the proposed study. This proposal aims to enable a new generation of high-speed, low-cost, wavelength-flexible swept source optical coherence tomography (SS-OCT) imaging device technology targeting applications in dental imaging and based on microelectromechanical systems vertical cavity surface emitting lasers (MEMS-VCSELs) and planar lightwave circuits (PLCs). MEMS-VCSELs provide an unmatched combination of high and variable axial scan rate, dynamic single mode operation enabling ...

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    7. Towards phase-stabilized Fourier domain mode-locked frequency combs

      Towards phase-stabilized Fourier domain mode-locked frequency combs

      Fourier domain mode-locked (FDML) lasers are some of the fastest wavelength-swept light sources, and used in many applications like optical coherence tomography (OCT), OCT endoscopy, Raman microscopy, light detection and ranging, and two-photon microscopy. For a deeper understanding of the underlying laser physics, it is crucial to investigate the light field evolution of the FDML laser and to clarify whether the FDML laser provides a frequency comb structure. In this case, the FDML would output a coherent sweep in frequency with a stable phase relation between output colours. To get access to the phase of the light field, a beat ...

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    8. Praevium Research Receives NIH Grant for Swept source retinal visible optical coherence tomography using broadly tunable frequency doubling of NIR MEMS-VCSELs

      Praevium Research Receives NIH Grant for Swept source retinal visible optical coherence tomography using broadly tunable frequency doubling of NIR MEMS-VCSELs

      Praevium Research Received a 2022 NIH Grant for $369,999 for Swept source retinal visible optical coherence tomography using broadly tunable frequency doubling of NIR MEMS-VCSELs . The principal investigator is Kirill Larin. Below is a summary of the proposed work. This proposal aims to develop a new generation of swept source optical coherence tomography (SS-OCT) technology operating at visible wavelengths near 530-600nm for retinal imaging and oximetry. This work will develop the first swept sources and SS-OCT systems in the visible wavelength range, enabling increased sensitivity, imaging range and speed compared to current visible spectral domain OCT (SD-OCT) systems with ...

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    9. Visual field simulation using optical coherence tomography and optical coherence tomographic angiography

      Visual field simulation using optical coherence tomography and optical coherence tomographic angiography

      Disclosed herein are methods for simulating the results of a visual field (VF) test using an optical coherence tomography (OCT) system. The disclosed methods may utilize structural information extracted from OCT image datasets, such as thickness measurements, or may utilize functional information, such as blood perfusion measurements, extracted from OCT angiography (OCTA) image datasets. Other embodiments may be described and claimed.

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    10. Bonded tunable VCSEL with bi-directional actuation

      Bonded tunable VCSEL with bi-directional actuation

      A MEMS tunable VCSEL includes a membrane device having a mirror and a distal-side electrostatic cavity for displacing the mirror to increase a size of an optical cavity. A VCSEL device includes an active region for amplifying light. Then, a proximal-side electrostatic cavity is defined between the VCSEL device and the membrane device is used to displace the mirror to decrease a size of an optical cavity.

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    11. Dual resonance akinetic dispersive cavity swept source at 900 kHz using a cFBG and an intensity modulator

      Dual resonance akinetic dispersive cavity swept source at 900 kHz using a cFBG and an intensity modulator

      In this paper, a fast dual resonance akinetic optical swept source operating at 1550 nm is demonstrated. Instead of modulating the optical amplifier gain reported in our previous studies, here we employ a fiber intensity modulator as a mode-locking element. A chirped fiber Bragg grating is used to provide sufficient dispersion in the laser cavity. A tuning range of 25 nm is obtained for a sweep frequency of ≈900 kHz with a 6-dB drop-off in sensitivity at 2.6-mm optical path difference.

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    12. Photonic integrated receiver

      Photonic integrated receiver

      A wavelength tunable laser device includes a gain element positioned in an optical cavity that provides optical gain to an optical signal. A frequency shifter that generates a frequency shift as a function of time is positioned in the optical cavity. The optical cavity is configured so that a magnitude of the frequency shift as a function of time generated by the frequency shifter is substantially equal to a frequency separation of a cavity mode of the cavity such that an output of the cavity generates laser light having a wavelength that tunes as a function of time.

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    13. Digitizer for an optical coherence tomography imager

      Digitizer for an optical coherence tomography imager

      A digitizer and processor device for a swept-source optical coherence tomography (SS-OCT) imaging system, comprising: an input configured to receive an OCT signal; a control input configured to receive a k-clock signal; a combiner unit (130) receiving the OCT signal and the k-clock signal configured to output a composite signal; a digitizing unit (60) arranged to convert the composite signal into a digital composite signal (69); a data processing unit (70) arranged to determine a profile of optical density in a sample that generated the OCT signal based on the digital composite signal (69). 2012/0162659 June 2012 Goldberg 2015 ...

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    14. Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      An ultra-broadband wavelength-swept laser (WSL) was generated using glass-clad Ti:sapphire crystal fiber as the gain media. Due to the low signal propagation loss of the crystal fiber, the swept laser has a tuning bandwidth of 250 nm (i.e., 683 nm to 933 nm) at a repetition rate of 1200 Hz. The steady-state and pulsed dynamics of the WSL were analyzed. The 0.018-nm instantaneous linewidth corresponds to a 3-dB coherence roll-off of 7 mm. When using the laser for swept-source optical coherence tomography, an estimated axial resolution of 1.8 µm can be achieved.

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    15. Fourier Domain Mode Locked Laser and Its Applications

      Fourier Domain Mode Locked Laser and Its Applications

      The sweep rate of conventional short-cavity lasers with an intracavity-swept filter is limited by the buildup time of laser signals from spontaneous emissions. The Fourier domain mode-locked (FDML) laser was proposed to overcome the limitations of buildup time by inserting a long fiber delay in the cavity to store the whole swept signal and has attracted much interest in both theoretical and experimental studies. In this review, the theoretical models to understand the dynamics of the FDML laser and the experimental techniques to realize high speed, wide sweep range, long coherence length, high output power and highly stable swept signals ...

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    16. Linewidth considerations for MEMS tunable VCSEL LiDAR

      Linewidth considerations for MEMS tunable VCSEL LiDAR

      The flexible membranes used in MEMS tunable VCSELs are so small and light that thermally induced vibrations can impact laser performance. We measure the thermal vibration spectrum of such a membrane showing peaks at the spatial vibration mode resonant frequencies of the membrane/plate. These vibrations result in a theoretical floor to the linewidth of the VCSEL. Frequency domain LiDAR and optical coherence tomography systems can get around this thermal linewidth limit with adequate clock measurement and processing. Essentially an OCT/LiDAR sweep with a concomitantly measured clock is a feed-forward linewidth reduction scheme. This can be achieved because the ...

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    17. Swept frequency photonic integrated circuit for absolute metrology

      Swept frequency photonic integrated circuit for absolute metrology

      A digital measuring device implemented on a photonic integrated circuit, the digital measuring device including a tunable laser source implemented on the photonic integrated circuit configured to sweep over a frequency range to provide multi-wavelength light, a first waveguide structure implemented on the photonic integrated circuit configured to direct a first portion of light from the laser source at a moving object and receive light reflected from the moving object, a second waveguide structure implemented on the photonic integrated circuit configured to combine a second portion of light from the laser source with the light reflected from the moving object ...

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    18. Swept Source-Optical Coherence Tomography Using New Recalibration Method for Nonlinear Sweeping Laser

      Swept Source-Optical Coherence Tomography Using New Recalibration Method for Nonlinear Sweeping Laser

      In this paper, Frequency Domain Mode Locked (FDML) wavelength swept laser with 55.027 kHz sweeping speed and 125 nm sweeping range has realized, and also a new method for recalibrating a nonlinear frequency sweeping of a swept laser has proposed. The Swept Source-Optical Coherence Tomography system using the proposed method has performed. For a mirror surface, the system showed the very clean 2-dimensional image and the advanced image speed of 7 frames per sec compared to the previous recalibration method.

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    19. RF properties of circular-ranging OCT signals

      RF properties of circular-ranging OCT signals

      Circular-ranging optical coherence tomography (CR–OCT) systems that use a time–stepped frequency comb source generate interference fringe signals that are more complex than those of a conventional swept–source OCT system. Here, we define a common terminology for describing these signals, and we develop a mathematical framework that relates the radio-frequency (RF) properties of these fringe signals to the parameters of the frequency comb source. With this framework, we highlight non-intuitive mechanisms whereby the design of the frequency comb source can affect imaging performance. We show, for example, that amplitude–pulsed time–stepped frequency comb sources have a sensitivity ...

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    20. External-cavity laser diode using acousto-optic deflector as tunable grating

      External-cavity laser diode using acousto-optic deflector as tunable grating

      In this study, a novel, to the best of our knowledge, external-cavity laser diode (ECLD) without a diffraction grating is proposed and demonstrated. In the proposed configuration, an acousto-optic deflector (AOD) acts not only as a deflector but also as a diffraction grating. Thus, the AOD functions as a wavelength-selective device, which helps improve the overall performance of the ECLD. In fact, the proposed configuration realizes a wide range of wavelength scanning with a simple configuration, highly efficient optical feedback, and a steady optical resonator with a constant cavity length. We confirm that the wavelengths scanned with the proposed ECLD ...

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    21. Precisely controlled chirped diode laser and coherent lidar system

      Precisely controlled chirped diode laser and coherent lidar system

      Frequency modulated lasers, LIDAR systems, and methods of controlling laser are disclosed. A laser source emits an optical beam having an optical frequency that changes in response to a signal applied to an input of the laser source. A laser driver that generates the signal applied to the input to cause the optical frequency to vary in accordance with a periodic frequency versus time function.

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    22. Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography

      Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography

      A method comprises: splitting laser light into sample light, reference light, and monitor light; routing the reference light into a reference arm of an OCT interferometer; routing the monitor light into a monitor device, which generates at least one optical monitor signal representing at least one time-dependent property of the monitor light; generating at least one electric monitor signal from the at least one optical monitor signal; illuminating in a point-shaped manner a sample with sample light, wherein the illumination point is guided on the surface of the sample along a predetermined trajectory; superimposing the light scattered by the sample ...

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      Mentions: Optores
    23. Broadband wavelength swept laser with bidirectional photonic resonance for high resolution optical coherence tomography

      Broadband wavelength swept laser with bidirectional photonic resonance for high resolution optical coherence tomography

      A light source with extended spectral bandwidth applied in optical coherence tomography (OCT) systems produces highly accurate micro - scale imaging structures owing to the attainable high - axial resolution. This study presents a wide tuning range of a wavelength - swept laser to improve the axial resolution. Linear cavity configuration was performed for bidirectional photonic resonance using two semiconductor optical amplifiers placed parallelly. A polygon scanner - based tunable filter produced a broa d scanning range of 155 nm from 917 nm to 1072 nm and an axial resolution of 3.4 μm in air. Bench - top imaging of a phantom made of ...

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    24. 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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      Mentions: Thorlabs
    1-24 of 455 1 2 3 4 ... 17 18 19 »
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