1. Articles in category: Tunable Sources

    1-24 of 269 1 2 3 4 ... 10 11 12 »
    1. Versatile Swept Source With Adjustable Coherence Length

      Versatile Swept Source With Adjustable Coherence Length

      An electronically controlled optical swept source at 1550 nm using mode locking in a dispersive ring cavity is described. Active mode-locking was achieved by directly modulating the current of a semiconductor optical amplifier (SOA) used as a gain medium. In the static regime, parameters such as linewidth, tuning bandwidth, and contrast were measured, whereas the axial range was determined dynamically. Two types of fiber, dispersion compensation and single mode, are employed in the laser ring cavity. It is demonstrated that the relative lengths of the two types of fiber have little effect on the linewidth, whereas more control on the ...

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    2. Dynamics of a short cavity swept source OCT laser

      Dynamics of a short cavity swept source OCT laser

      We investigate the behaviour of a short cavity swept source laser with an intra cavity swept filter both experimentally and theoretically. We characterise the behaviour of the device with real-time intensity measurements using a fast digital oscilloscope, showing several distinct regimes, most notably regions of mode-hopping, frequency sliding mode-locking and chaos. A delay differential equation model is proposed that shows close agreement with the experimental results. The model is also used to determine important quantities such as the minimum and maximum sweep speeds for the mode-locking regime. It is also shown that by varying the filter width the maximum sweep ...

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    3. Wide and fast wavelength-swept fiber lasers based on dispersion tuning for real-time OCT

      Wide and fast wavelength-swept fiber lasers based on dispersion tuning for real-time OCT

      Swept-Source Optical coherence tomography (SS-OCT) is a powerful tool for fast medical imaging. For the real-time 3D imaging, the wide tuning range over 100 nm and fast sweep rate over 100 kHz are typically required. We recently proposed a new wavelength-swept laser for SS-OCT. It is based on a principle called dispersion tuning. Since the cavity contains no mechanical components, such as tunable filters, we could achieve the very high sweep rate. In this review paper, we describe the principle of the dispersion-tuned swept lasers in detail and present our recent works on the application to the SS-OCT system.

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    4. Coherence revival multiplexed, buffered swept source optical coherence tomography: 400  kHz imaging with a 100  kHz source

      Coherence revival multiplexed, buffered swept source optical coherence tomography: 400  kHz imaging with a 100  kHz source

      The effective speed of a swept source optical coherence tomography (SSOCT) imaging system was quadrupled using efficient sweep buffering along with coherence revival and spatial multiplexing. A polarizing beam splitter and fold mirror assembly were used to create a dual spot sample arm with a common objective designed for near-diffraction-limited retinal imaging. Using coherence revival, a variable optical delay line allowed for separate locations within a sample to be simultaneously imaged and frequency encoded by carefully controlling the optical path length of each sample path. This method can be used to efficiently quadruple the imaging speed of any SSOCT system ...

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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 a 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 ...

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    6. Optores introduces the worlds first swept laser source with a sweep rate of up to 1.5 MHz for tomorrow's optical coherence tomography system

      Optores introduces the worlds first swept laser source with a sweep rate of up to 1.5 MHz for tomorrow's optical coherence tomography system

      Optores introduces the worlds first swept laser source with a sweep rate of up to 1.5 MHz for tomorrow's optical coherence tomography systems. The Optores swept source is based on all-fiber Fourier-domain mode-locked (FDML) laser technology. Designed for record speed, the Optores swept laser also features long coherence lengths and very high output powers beyond 80 mW. Three configuration variants are available to match your requirements.

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      Mentions: Optores
    7. Swept-source OCT and glaucoma

      Swept-source OCT and glaucoma

      A technology being investigated for use in posterior segment imaging may have a role in glaucoma diagnosis, according to the literature First there was time-domain optical coherence tomography (TD-OCT), then spectral-domain OCT (SD-OCT); now a newer technology—swept-source OCT—may be able to image structures that the previous technologies could not, according to researchers involved in clinical studies of the device. "With swept-source technology, a frequency swept light source and a high speed detector are used to detect the interference signal as a function of time, instead of a spectrometer and camera as in spectral-domain technology," explained James G. Fujimoto ...

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    8. Light Source And Optical Coherence Tomography Apparatus Including The Light Source

      Light Source And Optical Coherence Tomography Apparatus Including The Light Source

      A light source includes an upper electrode layer, a lower electrode layer, and an active layer interposed therebetween. At least one of the upper and lower electrode layers is divided into a plurality of electrodes separated from each other in an in-plane direction of the active layer. The separated electrodes independently inject current into a plurality of different regions in the active layer. The light source emits light by injecting current from the upper and lower electrode layers into the active layer, guide the light in the in-plane direction, and output the light. The plurality of different regions in the ...

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    9. Optical Semiconductor Device, Driving Method Thereof, And Optical Coherence Tomography Apparatus Having The Optical Semiconductor Device

      Optical Semiconductor Device, Driving Method Thereof, And Optical Coherence Tomography Apparatus Having The Optical Semiconductor Device

      The present invention provides an optical semiconductor device which can make a wavelength band of emitted light wider than that of a conventional optical semiconductor device. The optical semiconductor device includes: an active layer including a multiple quantum well structure; and at least one electrode pair for injecting an electric current into the active layer, wherein the multiple quantum well structure has a first quantum well and a second quantum well which is different from the first quantum well, and the first quantum well and the second quantum well are mutually different in at least two out of a composition ...

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    10. PhD scholarship in MEMS Tunable VCSELs for Optical Coherence Tomography at Technical University of Denmark

      PhD scholarship in MEMS Tunable VCSELs for Optical Coherence Tomography at Technical University of Denmark

      Applications are invited for a 3-year PhD position within the field of MEMS tunable VCSELs for optical coherence tomography (OCT). The project is multidisciplinary and will cover topics within the field of semiconductor optical devices, microelectromechanical systems, semiconductor technology and optical measurement systems. The project will be carried out at the Department of Photonics, Technical University of Denmark (DTU). Fast and widely tunable VCSELs are set to revolutionize the applications of tunable lasers for sensing. They promise not only low cost but also new properties like high dynamic coherence not normally associated with fast tunable lasers. Impressive results have been ...

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    11. Feature Of The Week 3/16/14: The University of Hong Kong Demonstrates MHz A-Line SS-OCT via Optical Time Stretching and Raman Amplification of Pulsed Source

      Feature Of The Week 3/16/14: The University of Hong Kong Demonstrates MHz A-Line SS-OCT via Optical Time Stretching and Raman Amplification of Pulsed Source

      We demonstrate all-optical ultrahigh-speed swept-source optical coherence tomography (OCT) based on amplified optical time-stretch (AOT). Such an inertia-free wavelength-swept mechanism, via group velocity dispersion, enables us to realize OCT with an A-scan rate well above MHz. More importantly, the key significance of AOT-OCT is its simultaneous broadband Raman amplification during the time-stretch process–greatly enhancing the detection sensitivity compared with prior attempts to apply optical time-stretch to OCT. Here, we report on an AOT-OCT system which is operated at an A-scan rate of 7.14 MHz, a superior roll-off performance (>2  mm/dB), a record-high sensitivity of time-stretch-based OCT (>80 ...

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    12. Filtered ASE swept source for OCT medical imaging

      Filtered ASE swept source for OCT medical imaging

      An integrated swept wavelength optical source uses a filtered ASE signal with an optical amplifier and tracking filter. This source comprises a micro optical bench, a source for generating broadband light, a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a narrowband tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier. A self-tracking arrangement is also possible where a single tunable filter ...

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    13. Integrated dual swept source for OCT medical imaging

      Integrated dual swept source for OCT medical imaging

      An optical coherence analysis system comprising: a first swept source that generates a first optical signal that is tuned over a first spectral scan band, a second swept source that generates a second optical signal that is tuned over a second spectral scan band, a combiner for combining the first optical signal and the second optical signal to form a combined optical signal, an interferometer for dividing the combined optical signal between a reference arm leading to a reference reflector and a sample arm leading to a sample, and a detector system for detecting an interference signal generated from the ...

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    14. Method and system for avoiding package induced failure in swept semiconductor source

      Method and system for avoiding package induced failure in swept semiconductor source

      Dry oxygen, dry air, or other gases such as ozone are hermetically sealed within the package of the external cavity laser or ASE swept source to avoid packaging-induced failure or PIF. PIF due to hydrocarbon breakdown at optical interfaces with high power densities is believed to occur at the SLED and/or SOA facets as well as the tunable Fabry-Perot reflector/filter elements and/or output fiber. Because the laser is an external cavity tunable laser and the configuration of the ASE swept sources, the power output can be low while the internal power at surfaces can be high leading ...

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    15. Single longitudinal mode Ytterbium doped fiber lasers with large proposed tuning range

      Single longitudinal mode Ytterbium doped fiber lasers with large proposed tuning range

      A 1,064 nm band Ytterbium doped fiber laser (YDFL) is proposed and investigated. Using 70 cm gain fiber and recycling pumping scheme, a high slope efficiency of 50 % and low threshold power of 53 mW are obtained. The power variation is less than 0.1 dB in 13 nm tuning span. Using the Vernier effect, near single frequency lasing is realized for the whole tuning range in 2 dBm output power. Have advantages of simpler structure, larger pump slope efficiency and possible shorter cavity, the YDFL may find potential applications in various ways.

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    16. A rapid, dispersion-based wavelength-stepped and wavelength-swept laser for optical coherence tomography

      A rapid, dispersion-based wavelength-stepped and wavelength-swept laser for optical coherence tomography

      Abstract: Optical-domain subsampling enables Fourier-domain OCT imaging at high-speeds and extended depth ranges while limiting the required acquisition bandwidth. To perform optical-domain subsampling, a wavelength-stepped rather than a wavelength-swept source is required. This preliminary study introduces a novel design for a rapid wavelength-stepped laser source that uses dispersive fibers in combination with a fast lithium-niobate modulator to achieve wavelength selection. A laser with 200 GHz wavelength-stepping and a sweep rate of 9 MHz over a 94 nm range at a center wavelength of 1550 nm is demonstrated. A reconfiguration of this source design to a continuous wavelength-swept light for conventional ...

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    17. Akinetic all-semiconductor programmable swept-source at 1550 nm and 1310 nm with centimeters coherence length

      Akinetic all-semiconductor programmable swept-source at 1550 nm and 1310 nm with centimeters coherence length

      We demonstrate, for the first time, OCT imaging capabilities of a novel, akinetic (without any form of movement in the tuning mechanism), all-semiconductor, all-electronic tunable, compact and flexible swept source laser technology at 1550 nm and 1310 nm. To investigate its OCT performance, 2D and 3D ex vivo and in vivo OCT imaging was performed at different sweep rates, from 20 kHz up to 200 kHz, with different axial resolutions, about 10 µm to 20 µm, and at different coherence gate displacements, from zero delay to >17 cm. Laser source phase linearity and phase repeatability standard deviation of <2 mrad ...

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    18. Axsun Technologies Announces Volume Purchase Order for Swept Laser Engines from Michelson Diagnostics Ltd.

      Axsun Technologies Announces Volume Purchase Order for Swept Laser Engines from Michelson Diagnostics Ltd.

      Axsun Technologies, Inc., a wholly-owned subsidiary of Volcano Corporation ( VOLC ) and a leading developer and manufacturer of advanced photonic components and subsystems, has received a volume purchase order for Swept Laser OCT Engines from Michelson Diagnostics Ltd. The Axsun Swept Laser OCT Engine will power the new Michelson Diagnostics' Vivosight Multi-Beam OCT system. The Vivosight Multi-Beam OCT system is the first OCT scanner to receive FDA 510(k) clearance for imaging skin in high definition, revealing subsurface tissue structure at unprecedented detail. "Axsun's Swept Laser OCT Engines are ideally suited for real-time OCT imaging in many imaging applications," said ...

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    19. Feature Of The Week 2/2/14: Tsinghua University.Demonstrates Linear-in-Wavenumber Swept Laser with an Acousto-Optic Deflector for OCT

      Feature Of The Week 2/2/14: Tsinghua University.Demonstrates Linear-in-Wavenumber Swept Laser with an Acousto-Optic Deflector for OCT

      Compared to the conventional time domain OCT, the frequency domain (FD) detection techniques enable a dramatic increase in imaging speed. Spectrometer-based FD-OCT (SD-OCT) systems are already widely used, especially for ophthalmic application in the 800 nm wavelength range. Alternatively, the application of FD-OCT systems based on a rapidly swept, narrowband light source, i.e. swept source OCT (SS-OCT) offers the additional advantages of dual balance detection, potentially longer ranging depth and higher imaging speeds. However, a general disadvantage of most FD-OCT systems is the requirement to resample and recalibrate the detected OCT interference fringe prior to fast Fourier transformation, in ...

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    20. Axsun’s New Lead-Free Tunable Laser Platform Meets Requirements of ROHS2 Directive

      Axsun’s New Lead-Free Tunable Laser Platform Meets Requirements of ROHS2 Directive

      Axsun Technologies Inc., a wholly-owned subsidiary of Volcano Corporation and a leading developer and manufacturer of advanced photonic components and subsystems, has announced the Qualification of their new Lead-Free Tunable Laser packaging platform. Axsun's new Lead-Free platform provides the same performance and reliability as previous generations and meets the requirements of the Reduction of Hazardous Substances (ROHS) Directive 2011/65/EU (also known as ROHS2). This new directive eliminates exemptions for several product categories, including Medical Devices that were present in the 2002 Directive. Axsun will begin sampling new Lead-Free Engines in May 2014. "Axsun's Swept Laser OCT ...

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    21. Refining imaging strategies to enhance understanding of congenital anomalies

      Refining imaging strategies to enhance understanding of congenital anomalies

      Optical coherence tomography in live animal models offers dynamic imaging capabilities for analyzing how aberrant morphologies and other birth defects occur during embryogenesis. Studying the mechanisms that regulate normal and abnormal development in murine (mouse) embryos can yield deeper insights into how and why anomalies sometimes appear. A great deal of knowledge can be gained from imaging studies of murine cells, tissues, and organs during early development that could ultimately lead to improved strategies for the prevention and treatment of birth defects in humans. In the past, such imaging has involved tissue staining to enable researchers to visualize cellular development ...

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    22. Simultaneous Dual-Band Wavelength-Swept Fiber Laser Based on Active Mode Locking

      Simultaneous Dual-Band Wavelength-Swept Fiber Laser Based on Active Mode Locking

      We report a simultaneous dual-band wavelength-swept laser based on the active mode locking method. By applying a single modulation signal, synchronized sweeping of two lasing-wavelengths is demonstrated without the use of a mechanical wavelength-selecting filter. Two free spectral ranges are independently controlled with a dual path-length configuration of a laser cavity. The static and dynamic performances of a dual-band wavelength-swept active mode locking fiber laser are characterized in both the time and wavelength regions. Two lasing wavelengths were swept simultaneously from 1263.0 to 1333.3 nm for the 1310 nm band and from 1493 to 1563.3 nm for ...

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    23. Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography

      Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography

      We report a novel linear-in-wavenumber ( k -linear) swept laser source based on an acousto-optic deflector (AOD). The AOD-based optical filter includes an acousto-optic deflector and a reflection grating. The laser may tune k linearly in wavenumber over time due to its appropriate configuration and is favorable for fast imaging because it avoids data resampling and recalibration, as are required in conventional swept source optical coherence tomography (SS-OCT). We achieved k -linearity with Pearson’s r correlation coefficients of 0.99995 without and 0.99997 with optimization. The laser has a tuning range of 50 nm, a 3 dB swept range ...

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    24. Deeply-Etched Optical MEMS Tunable Filter for Swept Laser Source Applications

      Deeply-Etched Optical MEMS Tunable Filter for Swept Laser Source Applications

      In this letter, we report a wide tuning range MEMS-based swept laser source using deep reactive ion etching on an SoI substrate. A MEMS Fabry–Pérot filter with a free-spectral range 105nm and a tuning range wider than 94 nm is presented. The measured transmission loss of the filter is between 10.2 and  13.6 dB . This filter is used to construct a swept laser source with 85 nm tuning range. These results represent the widest tuning range reported in literature for an in-plane SoI-MEMS based swept laser source using deeply-etched free-standing distributed-Bragg-reflection mirrors. The recorded tuning range ...

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      Mentions: Haitham Omran
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