1. Articles in category: Tunable Sources

    1-24 of 296 1 2 3 4 ... 11 12 13 »
    1. Vertical-cavity surface-emitting laser and method of fabricating the same

      Vertical-cavity surface-emitting laser and method of fabricating the same

      Provided are a wavelength swept vertical-cavity surface-emitting laser and a method of fabricating the same. The laser may include a substrate, a lower reflection layer on the substrate, an active layer on the lower reflection layer, a sacrificial layer disposed on a first side of the active layer, a stopper disposed on a second side of the active layer that may be spaced apart from the sacrificial layer, and an upper reflection layer fixed on the sacrificial layer, the upper reflection layer extending over the stopper and the active layer. The stopper defines a minimum separation distance between the upper ...

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    2. Device for swept source optical coherence domain reflectometry

      Device for swept source optical coherence domain reflectometry

      A device for swept-source optical coherence domain reflectometry (SS OCDR) on moveable samples, particularly human eyes, for obtaining A-scans, having a measuring range according to the sample length and having a laser light source which can be adjusted by a main wave number k.sub.0 and at least one receiver for the light dissipated from the sample, wherein the sample is illuminated on the sample surface by a measurement beam having a diameter D by way of a coupling device. The light source has a spectral line width of .delta.k<168 m.sup.-1 and the adjustment of ...

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    3. Tunable Surface Emitting Laser, Manufacturing Method Thereof, And Optical Coherence Tomography Apparatus Including Tunable Surface Emitting Laser

      Tunable Surface Emitting Laser, Manufacturing Method Thereof, And Optical Coherence Tomography Apparatus Including Tunable Surface Emitting Laser

      (EN) A tunable surface emitting laser includes on a semiconductor substrate (1) a first reflecting mirror (2); an active layer (4) on the first reflecting mirror which may be a DBR; a current confinement layer (6) resulting from partial oxidation of an AlGaAs layer; a conductive layer (7) on the current confinement layer (6) for providing a bias current to the active region; support portions (8) made from electrically insulating material like undoped GaAs; and a conductive film (9) which is provided above the conductive layer via a support portion (8) and which comprises a second reflecting mirror (11) like ...

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    4. High-speed En Face Optical Coherence Tomography Measurement System Developed

      High-speed En Face Optical Coherence Tomography Measurement System Developed

      A group of researchers led by OHMI Masato (Professor, Graduate School of Medicine, Osaka University) succeeded in developing a high-speed en face optical coherence tomography measurement system (en face OCT) that uses a function as optical deflector of crystals of potassium tantalate niobate (KTN). KTN crystal is expected to be used for optical deflectors and variable focusing lens developed by the Nippon Telegraph and Telephone Public Corporation (NTT). This group paid attention to KTN's feature as a deflector capable of high-speed control of laser beam angle according to applied pressure. The group used that feature for OCT technology, and ...

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      Mentions: Osaka University
    5. System and method for optimization of coherence length of tunable laser sources

      System and method for optimization of coherence length of tunable laser sources

      A system and method for adjusting the coherence length of a tunable laser to optimize measurements and reduce artifacts. A tuning element of the laser system modulates, adjusts, or controls parameters associate with the tunable laser, such that the output wavelength of the tunable laser is modulated or adjusted over a wavelength range within a time interval. Modulation of the parameter has the effect of increasing a linewidth of the tunable laser.

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    6. 4D optical coherence tomography-based micro-angiography achieved by 1.6-MHz FDML swept source

      4D optical coherence tomography-based micro-angiography achieved by 1.6-MHz FDML swept source

      We demonstrate the use of an ultra-high-speed swept-source optical coherence tomography (OCT) to achieve optical micro-angiography (OMAG) of microcirculatory tissue beds in vivo . The system is based on a 1310-nm Fourier domain mode-locking (FDML) laser with 1.6-MHz A-line rate, providing a frame rate of 3.415 KHz, an axial resolution of ∼ 10     μ m and signal to noise ratio of 102 dB. Motion from blood flow causes change in OCT signals between consecutive B-frames acquired at the same location. Intensity-based inter-frame subtraction algorithm is applied to extract blood flow from tissue background without any motion correction. We demonstrate the capability ...

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    7. System and method for stabilizing mode locked swept laser for OCT medical imaging

      System and method for stabilizing mode locked swept laser for OCT medical imaging

      An optical coherence analysis system uses a laser swept source that is constrained to operate in a stable mode locked condition by modulating a drive current to the semiconductor optical amplifier as function of wavelength or synchronously with the drive voltage of the laser's tunable element based on stability map for the laser.

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    8. Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      We present an ultrahigh-speed optical coherence tomography (OCT) based on an all-optical swept-source with an A-scan rate of 40 MHz. The inertia-free swept-source, which has its output power of 41.2 mW and tuning range of 40 nm and high scan linearity in wavenumber with Pearson’s correlation coefficients r of 0.9996, consists of a supercontinuum laser, an optical band-pass filter, a linearly chirped fiber Bragg grating, an erbium-doped fiber amplifier, and two buffer stages. With sensitivity of 87 dB, high-speed OCT imaging of biological tissue in vivo is also demonstrated.

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    9. Phase evolution and instantaneous linewidth of a Fourier domain mode locked laser

      Phase evolution and instantaneous linewidth of a Fourier domain mode locked laser

      An experimental and theoretical analysis of the dynamics of a Fourier domain mode locked laser, currently one of the fastest swept source lasers applied in optical coherence tomography, is performed. A novel time- resolved technique to measure the laser output electric field allows access to the phase dynamics of the laser and thus the coherence properties. A delay-differential equation model for the laser is used to analyse the system theoretically and via direct simulation. Numerical simulations of the laser output are in excellent agreement with experimentally measured data

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    10. System and method for generating an optimum side-mode suppression ratio continuous tuning path for a semiconductor tunable laser

      System and method for generating an optimum side-mode suppression ratio continuous tuning path for a semiconductor tunable laser

      A system and method to determine data sets of front mirror current, back mirror current and phase current that change the wavelength output by a semiconductor laser in a prescribed trajectory versus time, while maintaining the maximum side-mode suppression ratio at each point during the sweep.

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    11. Wavelength sweeping light source and imaging apparatus using the same

      Wavelength sweeping light source and imaging apparatus using the same

      A light source apparatus includes a laser oscillator equipped with a first optical resonator, a plurality of second optical resonators including input portions respectively connected in parallel to the first optical resonator, a plurality of light extraction units configured to extract a light beam from an output portion of each second optical resonator, and a light multiplexing unit configured to multiplex the light beam extracted from each light extraction unit, wherein the light source apparatus causes the light multiplexing unit to output a multiplexed light beam passed through the plurality of second optical resonators, an optical member having refractive index ...

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    12. Wideband Electrically-Pumped 1050 nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      Wideband Electrically-Pumped 1050 nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      In this paper, we present a 1050 nm electricallypumped micro-electro-mechanically-tunable vertical-cavitysurface- emitting-laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost & complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 ...

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    13. Santec offers Electrically Pumped Tunable VCSEL HSL-1

      Santec offers Electrically Pumped Tunable VCSEL HSL-1

      Product Name: Tunable VCSEL Production code: HSL-1 Santec, a leading manufacturer of tunable lasers, optical instruments, and fiber-optic components, introduces the latest addition to its range of tunable lasers for spectroscopy and optical coherence tomography (OCT). The HSL-1 is based on advanced electrically pumped VCSEL (Vertical Cavity Surface Emitting Laser) technology. An attractive laser for SS-OCT applications the HSL-1 takes advantage of a number of features intrinsic to VCSELs to deliver best-in-class performance, including long coherence length, variable scan speed and low signal noise. The HSL-1 has been designed with system integration in mind; a compact, efficient package the laser ...

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      Mentions: Santec
    14. Analysis of a spinning polygon wavelength swept laser

      Analysis of a spinning polygon wavelength swept laser

      It has been known for quite some time that spinning polygon, and similar, swept lasers used in OCT favor the short to long wavelength sweep direction because of four wave mixing in the gain medium. Here we have reformulated the problem in the time domain and show experimentally and through numerical simulation that these lasers are pulsed. The emitted pulses modulate the gain medium refractive index to red shift the light. Instead of new wavelengths being built up slowly from spontaneous emission, each pulse hops to a longer wavelength by nonlinear means, tracking the tunable filter. This allows high speed ...

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    15. Development of novel high-speed en face optical coherence tomography system using KTN optical beamdeflector

      Development of novel high-speed en face optical coherence tomography system using KTN optical beamdeflector

      We developed a novel high-speed en face optical coherence tomography (OCT) system using a KTa 1– x Nb x O 3 (KTN) optical beam deflector. Using the imaging system, fast scanning was performed at 200 kHz by the KTN beam deflector, while slow scanning was performed at 400 Hz by the galvanometer mirror. In a preliminary experiment, we obtained en face OCT images of a human fingerprint at 400 fps. This is the highest speed reported in time-domain en face OCT imaging and is comparable to the speed of swept-source OCT. A 3D-OCT image of a sweat gland was also ...

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    16. WAVELENGTH-TUNABLE Vertical Cavity Surface Emitting Laser For Swept Source Optical Coherence Tomography System

      WAVELENGTH-TUNABLE Vertical Cavity Surface Emitting Laser For Swept Source Optical Coherence Tomography System

      A wavelength-tunable vertical-cavity surface-emitting laser (VCSEL) with the use of micro-electromechanical system (MEMS) technology is provided as a swept source for Optical Coherence Tomography (OCT). The wavelength-tunable VCSEL comprises a bottom mirror of the VCSEL, an active region, and a MEMS tunable upper mirror movable by electrostatic deflections. The bottom mirror comprising a GaAs based distributed Bragg reflector (DBR) stack, and the active region comprising multiple stacks of GaAs based quantum dot (QD) layers, are epitaxially grown on a GaAs substrate. The MEMS tunable upper mirror includes a membrane part supported by suspension beams, and an upper mirror comprising a ...

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      Mentions: InPhenix
    17. Tuneable laser source

      Tuneable laser source

      Described herein is a laser (1) having a cavity for supporting oscillation of an electromagnetic signal to provide lasing action. A gain element (5) provides a source of stimulated emission for amplifying the oscillating signal. The laser also includes a wavelength selective element (7), which includes a reflecting element and a polarization modifying element. The reflecting element selectively defines a predetermined wavelength and the polarization modifying element selectively modifies the polarization of the signal component at the predetermined wavelength so as to provide high selectivity. The wavelength selective element (7) rotates the signal polarization at the predetermined wavelength into an ...

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      Mentions: Finisar
    18. Breathing laser as an inertia-free swept source for high-quality ultrafast optical bioimaging

      Breathing laser as an inertia-free swept source for high-quality ultrafast optical bioimaging

      We demonstrate an all-fiber breathing laser as inertia-free swept source (BLISS), with an ultra-compact design, for the emerging ultrafast bioimaging modalities. The unique feature of BLISS is its broadband wavelength-swept operation ( ∼ 60     nm ) with superior temporal stability in terms of both long term (0.08 dB over 27 h) and shot-to-shot power variations (2.1%). More importantly, it enables a wavelength sweep rate of > 10     MHz ( ∼ 7 × 10 8     nm / s )—orders-of-magnitude faster than the existing swept sources based on mechanical or electrical tuning techniques. BLISS thus represents a practical and new generation of swept source operating in the unmet ...

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    19. Coherence improvement in dispersion-tuned swept laser by pulse modulation

      Coherence improvement in dispersion-tuned swept laser by pulse modulation

      The dispersion-tuned swept laser (DTSL) is a fast and wideband swept source applicable in swept-source optical coherence tomography (SS-OCT). However, it suffers from coherence degradation at high sweep rates. The coherence in the DTSL, which can be improved by pulse modulation in place of sinusoidal modulation, is demonstrated. A coherence length of 8 mm is obtained at a sweep rate of 50 kHz using 100 ps pulse modulation.

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    20. Feature Of The Week 11/9/14: Dynamics of a Short Cavity Swept Source OCT Laser

      Feature Of The Week 11/9/14: Dynamics of a Short Cavity Swept Source OCT Laser

      Great advances in OCT speed and sensitivity have been possible due to the introduction of fast frequency swept laser sources. One of the most commonly used swept source devices is a short (~5 cm) cavity Fabry-Perot laser. We present both experimental characterisation and numerical modelling of such an OCT swept source and also analyse the underlying physics to better understand how such sources may be optimised. For the experimental characterisation we use a high-speed digital oscilloscope for real time analysis of the fast temporal intensity and frequency evolution. For the theoretical analysis we use a set of delay differential equations ...

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    21. Wavelength-swept lasers and their application to fiber optic sensors

      Wavelength-swept lasers and their application to fiber optic sensors

      The wavelength swept laser (WSL) is a promising optical source in optical coherence tomography, optical fiber sensor, and optical beat source generation. It is demonstrated by employing a narrowband wavelength-scanning filter, such as a fast rotating polygonal-scanner-filter, a diffraction grating on a galvo-scan mirror, or a fiber Fabry-Perot tunable filter (FFP-TF). In this manuscript, we present our researches on the dynamic fiber-optic sensors. Two kinds of WSLs are used to demonstrate the dynamic measurement in the fiber-optic sensors. One is the WSL using a polygon-scanner-based wavelength filter and the other is the Fourier domain mode-locked (FDML) WSL using a FFP-TF ...

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      Mentions: Min Yong Jeon
    22. System and method for improved resolution, higher scan speeds and reduced processing time in scans involving swept-wavelength interferometry

      System and method for improved resolution, higher scan speeds and reduced processing time in scans involving swept-wavelength interferometry

      A system and method for measuring an interferometric signal from a swept-wavelength interferometer by scanning a tunable laser source over two wavelength ranges, whose centers are separated substantially more than the length of wavelength ranges. The spatial resolution of the measurement is determined by the inverse of the wavelength separation between a first and second wavelength region, as well as by the wavelength range of the first and second regions. An electronically tunable laser may be utilized to produce two wavelength ranges that are widely separated in wavelength. Such a system and method has wide applications to the fields of ...

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    23. All-fiber wavelength swept ring laser based on Fabry-Perot filter for optical frequency domain imaging

      All-fiber wavelength swept ring laser based on  Fabry-Perot filter for optical frequency domain  imaging

      Innovations in laser engineering have yielded several novel configurations for high repetition rate, broad sweep range, and long coherence length wavelength swept lasers. Although these lasers have enabled high performance frequency-domain optical coherence tomography, they are typically complicated and costly and many require access to proprietary materials or devices. Here, we demonstrate a simplified ring resonator configuration that is straightforward to construct from readily available materials at a low total cost. It was enabled by an insight regarding the significance of isolation against bidirectional operation and by configuring the sweep range of the intracavity filter to exceed its free spectral ...

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    24. Praevium Research Receives NIH Grant for VCSEL Technology for Ultrahigh Speed OCT Retinal and Anterior Eye Imaging.

      Praevium Research Receives NIH Grant for VCSEL Technology for Ultrahigh Speed OCT Retinal and Anterior Eye Imaging.

      Praevium Research Receives a 2014 NIH Grant for $426,962 for VCSEL Technology for Ultrahigh Speed OCT Retinal and Anterior Eye Imaging. The principal investigator is Vijaysekhar Jayaraman. The program began in 2012 and ends in 2015. Below is a summary of the proposed work. The ultimate goal of this program is to enable a new generation of high performance, low cost ophthalmic Optical Coherence Tomography OCT technology based on new MEMS-tunable vertical cavity surface-emitting laser (MEMS-VCSEL) swept light sources. This will be accomplished by developing, validating, and commercializing VCSEL technology for swept source OCT (SS-OCT) at 850nm and 1050nm ...

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    1-24 of 296 1 2 3 4 ... 11 12 13 »
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