1. Articles in category: Tunable Sources

    1-24 of 319 1 2 3 4 ... 12 13 14 »
    1. 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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    2. 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
    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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
    9. 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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    10. 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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    11. 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 microelectromechanical 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
    12. A New Component Toolbox For 2 Micron Fiber Lasers

      A New Component Toolbox For 2 Micron Fiber Lasers

      Gooch & Housego now offers a full suite of passive and active components to enable high power, all-fiber laser systems at 2 µm for use in materials processing, surgery and sensing. Developed over three years during the ISLA project (Integrated disruptive components for 2 µm fiber Lasers), the components draw on G&H core competencies in design and manufacturing of fused fiber components and acousto-optic devices. Fiber lasers have become a workhorse in material processing, where they are valued for their high power, low maintenance, and the convenience of routing light directly to the sample. Most existing fiber lasers operate at ...

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      Mentions: Gooch & Housego
    13. System and method for generating and utilizing sample trigger blanking to obviate spurious data and increase sweep rate in an akinetic path-based swept laser

      System and method for generating and utilizing sample trigger blanking 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 are generated for input to a measurement system by the semiconductor laser. The series of triggering signals include a non-uniform ...

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    14. New lasers offer low cost industrial processing and novel surgical possibilities

      New lasers offer low cost industrial processing and novel surgical possibilities

      EU scientists have developed efficient new fibre optic lasers that deliver short wavelengths for accurate polymer material processing, at incredible strength and low cost. The consortium behind the new innovations, developed through the ISLA project, is now in the process of marketing some of these cutting edge devices.

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    15. VECSELs: Innovative light sources for PDT - Photodiagnosis and Photodynamic Therapy

      VECSELs: Innovative light sources for PDT - Photodiagnosis and Photodynamic Therapy

      Photodynamic therapy (PDT) with porphyrins and red light (610–630 nm) is finding increasing clinical application for both the eradication of relatively small tumors and the palliation of inoperable or obstructive tumors. PDT also shows some promise for the sterilization of the tumor bed after surgical removal of neoplastic masses. Optically pumped vertical external-cavity surface-emitting lasers (VECSELs) appear to be a very innovative and efficient technology in this specific wavelength range. Furthermore, VECSELs are power scalable and wavelength tunable, and are an appealing light source for PDT.

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      Mentions: Mircea Guina
    16. Device, light source device, and imaging apparatus using the same

      Device, light source device, and imaging apparatus using the same

      A device includes a first resonating cavity and a second resonating cavity. The first resonating cavity includes a first end surface and a second end surface. The first resonating cavity has a first free spectral range. The first free spectral range is a first frequency of a wavelength dependent ripple in a gain of the device that is a function of a first distance between the first end surface and the second end surface. The second resonating cavity includes a third end surface and a fourth end surface. A second distance between the third end surface and the fourth end ...

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    17. Self-sweeping laser could dramatically shrink 3-D mapping systems

      Self-sweeping laser could dramatically shrink 3-D mapping systems

      A new approach that uses light to move mirrors could usher in a new generation of laser technology for a wide range of applications, including remote sensing, self-driving car navigation and 3D biomedical imaging. A team of University of California, Berkeley, engineers led by Connie Chang-Hasnain, a professor of electrical engineering and computer sciences, used a novel concept to automate the way a light source changes its wavelength as it sweeps the surrounding landscape. They report their findings in the journal Scientific Reports , to be published Thursday, Sept. 3. The advance could have implications for imaging technology using LIDAR, or ...

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    18. Laser optomechanics

      Laser optomechanics

      Cavity optomechanics explores the interaction between optical field and mechanical motion. So far, this interaction has relied on the detuning between a passive optical resonator and an external pump laser. Here, we report a new scheme with mutual coupling between a mechanical oscillator supporting the mirror of a laser and the optical field generated by the laser itself. The optically active cavity greatly enhances the light-matter energy transfer. In this work, we use an electrically-pumped vertical-cavity surface-emitting laser (VCSEL) with an ultra-light-weight (130 pg) high-contrast-grating (HCG) mirror, whose reflectivity spectrum is designed to facilitate strong optomechanical coupling, to demonstrate optomechanically-induced ...

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    19. System and method for generating and utilizing a valid sweep vector 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 vector 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 are generated for input to a measurement system by the semiconductor laser. The electromagnetic energy output from the semiconductor laser ...

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    20. Swept-Source OCT: Patent License Agreement between Massachusetts General Hospital and Heidelberg Engineering

      Swept-Source OCT: Patent License Agreement between Massachusetts General Hospital and Heidelberg Engineering

      Heidelberg Engineering has entered into a patent license agreement with Massachusetts General Hospital (MGH) in Boston. The agreement grants global and exclusive rights to 77 basic patents and patent applications which relate to swept-source OCT technology and its application in ophthalmology. Spectral domain OCT has become indispensable to eye care professionals worldwide to diagnose and follow-up patients with diseases of the posterior segment of the eye, such as age-related macular degeneration, diabetic retinopathy, or glaucoma. Swept-source OCT technology has specific characteristics which are ideal to acquire comprehensive information about a wide variety of properties of the anterior part of the ...

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    21. Scanning Laser Ophthalmoscopes

      Scanning Laser Ophthalmoscopes

      A scanning laser ophthalmoscope (SLO) for imaging the retina of an eye comprises a source ( 12 ) of collimated light, a scanning device ( 14, 16, 1328, 1319 ), a scan transfer device ( 20 ) and a detector ( 1310 ). The scan transfer device has a first focus ( 16 ) at which an apparent point source is provided and a second focus ( 24 ) at which an eye ( 524, 1324 ) may be accommodated. The scan transfer device transfers a two-dimensional collimated light scan from the apparent point source into the eye. An optical coherence tomography (OCT) system ( 900 ) is combined with the SLO, the OCT system providing ...

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    22. Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers

      Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers

      We analyze the physics behind the newest generation of rapidly wavelength tunable sources for optical coherence tomography (OCT), retaining a single longitudinal cavity mode during operation without repeated build up of lasing. In this context, we theoretically investigate the currently existing concepts of rapidly wavelength-swept lasers based on tuning of the cavity length or refractive index, leading to an altered optical path length inside the resonator. Specifically, we consider vertical-cavity surface-emitting lasers (VCSELs) with microelectromechanical system (MEMS) mirrors as well as Fourier domain mode-locked (FDML) and Vernier-tuned distributed Bragg reflector (VT-DBR) lasers. Based on heuristic arguments and exact analytical solutions ...

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    23. 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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    1-24 of 319 1 2 3 4 ... 12 13 14 »
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