1. Articles in category: Tunable Sources

    1-24 of 333 1 2 3 4 ... 12 13 14 »
    1. Wavelength tunable light source

      Wavelength tunable light source

      To provide a wavelength tunable light source which can both ensure operation speed and reduce a drive voltage. A wavelength tunable light source according to the present invention includes a pair of reflectors at least one of which is a movable reflector, an active layer provided between the pair of reflectors, and a beam on part of which the movable reflector is formed and which is supported by a support member. The beam includes a blade part projecting between the support member and the movable reflector in a direction intersecting a stretching direction of the beam, and a center of ...

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    2. Full-Field Optical Coherence Tomography Using Galvo Filter-Based Wavelength Swept Laser

      Full-Field Optical Coherence Tomography Using Galvo Filter-Based Wavelength Swept Laser

      We report a wavelength swept laser-based full-field optical coherence tomography for measuring the surfaces and thicknesses of refractive and reflective samples. The system consists of a galvo filter–based wavelength swept laser and a simple Michelson interferometer. Combinations of the reflective and refractive samples are used to demonstrate the performance of the system. By synchronizing the camera with the source, the cross-sectional information of the samples can be seen after each sweep of the swept source. This system can be effective for the thickness measurement of optical thin films as well as for the depth investigation of samples in industrial ...

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    3. Optimized device for swept source optical coherence domain reflectometry and tomography

      Optimized device for swept source optical coherence domain reflectometry and tomography

      Optimized device for swept source optical coherence domain reflectometry and tomography. In the coherence-optical device, light, with the aid of an interferometer, is used for distance-measuring and imaging purposes on reflecting and scattering areas of the human eye. The optimized device according to the invention consists of includes a tunable light source, matched to the sought-after measurement region ZOCT, with a resonator length LR, an interferometric measurement arrangement, a data capturing unit for capturing the light portions scattered back from the sample and a data processing unit. Here the resonator length LR of the tunable light source is matched not ...

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    4. Wavelength-swept fiber laser based on acousto-optic tuning method

      Wavelength-swept fiber laser based on acousto-optic tuning method

      In this study, we have demonstrated a wavelength-swept fiber laser based on an acousto-optic tunable filter(AOTF) as a selective element and a semiconductor optical amplifier(SOA) as a gain medium in an internal fiber ring cavity. The light deriving from one port of the SOA goes through an optical isolator, the AOTF, a fiber coupler and a polarized controller successively, then it goes back to the other port of the SOA to form a ring cavity. The laser output is from another port of the fiber coupler. The laser made by this method is mainly used for swept-source optical ...

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    5. System and method for interlacing differing coherence length sweeps to improve OCT image quality

      System and method for interlacing differing coherence length sweeps to improve OCT image quality

      A system and method for sweeping electromagnetic radiation over a first coherence length and a second length over a range of wavelengths to generate an image. Electromagnetic radiation having a first coherence length is generated and swept over a range of wavelengths. Electromagnetic radiation having a second coherence length is generated and swept over a range of wavelengths. The electromagnetic radiation is splitting through a reference path and a sample path; Electromagnetic radiation returned from the reference path and the sample path is detected, wherein the detector generates output signals corresponding to the received electromagnetic radiation. In one embodiment, the ...

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    6. Long-range and wide field of view optical coherence tomography for in vivo 3D imaging of large volume object based on akinetic programmable swept source

      Long-range and wide field of view optical coherence tomography for in vivo 3D imaging of large volume object based on akinetic programmable swept source

      Current optical coherence tomography (OCT) imaging suffers from short ranging distance and narrow imaging field of view (FOV). There is growing interest in searching for solutions to these limitations in order to expand further in vivo OCT applications. This paper describes a solution where we utilize an akinetic swept source for OCT implementation to enable ~10 cm ranging distance, associated with the use of a wide-angle camera lens in the sample arm to provide a FOV of ~20 x 20 cm 2 . The akinetic swept source operates at 1300 nm central wavelength with a bandwidth of 100 nm. We propose ...

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    7. Optimization of a dispersion-tuned wavelength-swept fiber laser for optical coherence tomography

      Optimization of a dispersion-tuned wavelength-swept fiber laser for optical coherence tomography

      We optimized parameters of a dispersion-tuned wavelength-swept fiber laser by numerically analyzing dynamic characteristics. The optimized laser is experimentally demonstrated and applied to the swept-source optical coherence tomography (SS-OCT) system. The dispersion-tuned wavelength-swept laser (DT-WSL) is a unique tunable fiber laser, whose lasing wavelength can be tuned rapidly without any mechanical tunable filters. Although the wavelength of a DT-WSL can be swept rapidly and widely, the broadening of the instantaneous spectral width at a high sweep rate has been a critical drawback for SS-OCT applications. Numerical simulations have shown that higher modulation frequencies for active mode-locking lead to narrower instantaneous ...

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    8. Regenerative mode locked laser swept source for OCT medical imaging

      Regenerative mode locked laser swept source for OCT medical imaging

      An optical coherence analysis system uses a laser swept source that is constrained to operate in a mode locked condition using regenerative mode-locking. This is accomplished by synchronously changing the laser cavity's net gain and/or phase based on time varying intensity of the swept optical signal generated by the laser. This produces a stable pulsation behavior, which is associated with smooth tuning (low optical frequency reference clock jitter) and low relative intensity noise (RIN).

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    9. Wavelength tunable photon source with sealed inner volume

      Wavelength tunable photon source with sealed inner volume

      There is presented a method of providing a wavelength tunable photon source (200), comprising bonding a first element (101) with a first mirror (106), a second element (102) with a second mirror (108) and a third element (103) with a photon emitter together in a structure enclosing an inner volume (214) being a sealed volume, and forming a bonding interface (212) which is gas-tight, so that the first mirror (106) is placed in the inner volume (214) so the first mirror (106) may move within the inner volume (214). The method provides a relatively simple way of obtaining a tunable ...

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    10. Surface emitting laser having a factor of equivalent refractive index constraint by scaled central wavelengths and optical coherence tomography apparatus equipped with such surface emitting laser

      Surface emitting laser having a factor of equivalent refractive index constraint by scaled central wavelengths and optical coherence tomography apparatus equipped with such surface emitting laser

      A surface emitting laser according to the present invention includes a lower reflector, a first spacer layer, an active layer, a second spacer layer composed of a semiconductor material, a gap section formed of at least one of vacuum and gas, and an upper reflector in the written order, and also includes a control mechanism that changes a distance between an interface between the second spacer layer and the gap section and an interface between the upper reflector and the gap section. An optical path length n.sub.eff.times.d extending from an interface between the lower reflector and ...

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    11. Amplified widely tunable short cavity laser

      Amplified widely tunable short cavity laser

      An amplified tunable source includes a short-cavity laser coupled to an optical amplifier for high power, spectrally shaped operation. The short-cavity laser is coupled to a quantum well semiconductor optical amplifier with two quantum states for broadened gain. Two preferred wavelength ranges of the amplified tunable source include 1200-1400 nm and 800-1100 nm. Also disclosed is the short cavity tunable laser coupled to a fiber amplifier. Various combinations of tunable optical filters with the amplified tunable source to reduce noise or improve spectral purity are presented.

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    12. Tunable short cavity laser sensor

      Tunable short cavity laser sensor

      Optical systems employ a tunable source which includes a short cavity laser with a large free spectral range cavity, fast tuning response, and single transverse and longitudinal mode operation. Systems for optical spectroscopy with optimized scanning, a system for optical beam steering and a system for a tunable local oscillator are disclosed.

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    13. Polarization stable widely tunable short cavity laser

      Polarization stable 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. A short cavity laser with a large free spectral range cavity, fast tuning response and single transverse, longitudinal and polarization mode operation is disclosed. Methods for obtaining polarization stable operation of the tunable source are presented.

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    14. System and method for generating and utilizing a valid sweep signal to obviate spurious data and increase sweep rate in an akinetic path-based swept laser

      System and method for generating and utilizing a valid sweep signal to obviate spurious data and increase sweep rate in an akinetic path-based swept laser

      A system and method for triggering data acquisition in a semiconductor laser system including outputting electromagnetic energy from the semiconductor laser over a range of wavelengths according to a signaling path. The signaling path includes a plurality of discrete data inputs to the semiconductor laser for outputting electromagnetic energy over a range of wavelengths and the signaling path includes one or more perturbances in transitioning from one wavelength to another wavelength along the signaling path. A series of triggering signals for input to a measurement system is generated by the semiconductor laser. The semiconductor laser also generates a series of ...

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    15. Tunable Emission Wavelength Stacked InAs/GaAs Quantum Dots by Chemical Beam Epitaxy for Optical Coherence Tomography

      Tunable Emission Wavelength Stacked InAs/GaAs Quantum Dots by Chemical Beam Epitaxy for Optical Coherence Tomography

      We report on Chemical Beam Epitaxy (CBE) growth of wavelength tunable InAs/GaAs quantum dots (QD) based superluminescent diode’s active layer suitable for Optical Coherence Tomography (OCT). The In-flush technique has been employed to fabricate QD with controllable heights, from 5 nm down to 2 nm, allowing a tunable emission band over 160 nm. The emission wavelength blueshift has been ensured by reducing both dots’ height and composition. A structure containing four vertically stacked height-engineered QDs have been fabricated, showing a room temperature broad emission band centered at 1.1 µm. The buried QD layers remain insensitive to the ...

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    16. Wavelength swept light source

      Wavelength swept light source

      A wavelength swept light source includes a sawtooth waveform as a main waveform and an exponential component of the sawtooth waveform to the controlled voltage of the electro-optic deflector. The controlled voltage is controlled so that, as an oscillation wavelength to be swept is swept towards a longer wavelength side, a change rate of the oscillation wavelength is increased.

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      Mentions: NTT
    17. Master/slave interferometry – ideal tool for coherence revival swept source optical coherence tomography

      Master/slave interferometry – ideal tool for coherence revival swept source optical coherence tomography

      In this paper, we demonstrate that the master slave (MS) interferometry method can significantly simplify the practice of coherence revival swept source optical coherence tomography (OCT) technique. Previous implementations of the coherence revival technique required considerable resources on dispersion compensation and data resampling. The total tolerance of the MS method to nonlinear tuning, to dispersion in the interferometer and to dispersion due to the laser cavity, makes the MS ideally suited to the practice of coherence revival. In addition, enhanced versatility is allowed by the MS method in displaying shorter axial range images than that determined by the digital sampling ...

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    18. Swept source optical coherence tomography and method for stabilizing phase thereof

      Swept source optical coherence tomography and method for stabilizing phase thereof

      In an embodiment, a computer 16, which generates tomographic images based on spectral interference signals detected by a light detector 15 from overlaid reference light emitted by a swept-source type light source 2 of a SS-OCT, split, and then reflected by a fixed reference mirror 8 on one hand and object light reflected by an object to be measured 6 on the other, is caused to function to apply rough correction using a first correction means and then apply detailed correction using a second correction means, to stabilize the phases of the SS-OCT. The phases can be stabilized by eliminating ...

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    19. SNR of swept SLEDs and swept lasers for OCT

      SNR of swept SLEDs and swept lasers for OCT

      A back-to-back comparison of a tunable narrow-band-filtered SLED (TSLED) and a swept laser are made for OCT applications. The two sources are similar in terms of sweep speed, tuning range and coherence length. A fundamental issue with a TSLED is that the RIN is proportional to 1/linewidth, meaning that the longer the coherence length, the higher the RIN and clock jitter. We show that the TSLED has an SNR limit that causes noise streaks at points of high reflection in images. The laser, which is shot noise limited, does not exhibit this effect. We add noise terms proportional to ...

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    20. IEEE Boston Photonics Society Talk on Swept Source Lasers by Bart Johnson

      IEEE Boston Photonics Society Talk on Swept Source Lasers by Bart Johnson

      The development of swept source lasers has made high-speed optical coherence tomography (OCT) cost effective at 1060 and 1310 nm wavelengths. Axsun Technologies manufactures this type of source and has made inroads into ophthalmology and cardiology applications. The 1060 product, for example, tunes 990-1100 nm at a 100 kHz sweep rate. This external cavity diode laser is tuned by a MEMS Fabry-Perot filter. The act of rapidly sweeping the filter induces a mode-locking behavior. This is because when the pulses deplete the gain medium they are red shifted due to the index rise in the semiconductor optical amplifier associated with ...

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    21. Surface emitting laser and optical coherence tomography apparatus including the same

      Surface emitting laser and optical coherence tomography apparatus including the same

      A surface emitting laser includes a lower reflector, an active layer, and an upper reflector that are arranged in that order; an air gap provided between the active layer and the upper reflector; and a slab provided on an optical path of the air gap and having a refractive index that is higher than a refractive index of the air gap. A position of at least one of the upper reflector and the lower reflector in an optical axis direction is changed to change a wavelength of emitted light. In the case where the position of the upper reflector is ...

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    22. Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

      Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

      We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation ...

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      Mentions: Superlum
    23. Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction

      Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction

      A novel, time-resolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography applications, with a spectral bandwidth of 18 THz. This novel analysis of the complete electric field reveals the modal structure and modal evolution of the device as well as providing a time-resolved real-time characterization of the optical spectrum, linewidth and coherence properties of a dynamic rapidly swept laser.

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    24. Swept-Source optical coherence tomography correlations between retina and choroid before and after vitrectomy for epiretinal membranes

      Swept-Source optical coherence tomography correlations between retina and choroid before and after vitrectomy for epiretinal membranes

      Purpose To describe retinal and choroidal morphology before and after surgery for epiretinal membranes (ERM) in Swept Source OCT (SS-OCT). Additionally, to evaluate factors responsible for visibility of the suprachoroidal layer (SCL) and suprachoroidal space (SCS). Design Prospective consecutive case series. Material and Methods 29 eyes of 29 patients with symptomatic, idiopathic ERM were included. Pars plana vitrectomy with ERM removal and ILM peeling was performed. We examined patients with SS-OCT twice preoperatively (9-12 months and one week before surgery), then postoperatively at 1 week, 6 and 12 months. Results Twelve months after surgery visual acuity improved to 20/50 ...

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    1-24 of 333 1 2 3 4 ... 12 13 14 »
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