(GaAl)As SQW superluminescent diodes with extremely low coherence length

Semenov, A T; Batovrin, V.K.; Garmash, I. A.; Shidlovsky, V. R.; Shramenko, M V; Yakubovich, S D

doi:10.1049/el:19950214

Cited by 42 publications

(20 citation statements)

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“…4a). For 22 out of 27 investigated PEWs, medium "spectral" lifetime is shorter than "power" one, determined by (1) or (2). For most of them, Tp is several times greater than TS.…”

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confidence: 86%

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Changes in output characteristics of broad-band superluminescent diodes in the process of long-term operation

Андреева¹,

Il'chenko²,

Kostin³

et al. 2011

2011 11th International Conference on Laser and Fiber-Optical Networks Modeling (LFNM)

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Methods and results of reliability tests of SQW broad-band superluminescent diodes (SLD-37 series), widely used in optical coherence tomography (OCT) are presented. Main attention was paid to the alteration of SLD spectral characteristics in the aging process. It is shown that the usage of these methods in the input control of processed epiwafers deployed in the production of active elements for SLD-modules ensures the estimation of their expected life time (MTTF).Broad-band SLDs are widely used as light sources in OCT [1]. For the ophthalmic OCT the most popular are SLDs of NIR range 800 -900 nm, based on QW heterostructures. Such lightsources of SLD-37 series are used worldwide in dozens of laboratories and companies that deal with research, development and production of new OCT systems, mainly for ophthalmic uses. Since their development, over 10000 SLD-37 modules have been fabricated and realized.These SLDs are based on SQW (GaAl)As/GaAs SC DH [2]. Their active channel is a traditional single transverse mode 4 flm-width ridge waveguide. Free-space output power amounts 5 -35 mW, depending on technical requirements. Density of light on the facets of the crystal amounts 0.12 -0.85 MW/cm 2 , or 1.2 -8.5 mW/flm respectively. These values are far below catastrophic optical damage threshold, which is about 3 -6 MW/cm 2 for these devices. Huge statistics shows that except for so-called "infant mortality", catastrophic degradation of such SLDs occurs very rarely. In contrast to laser diodes and SLDs based on bulk SC DH, spectrum shape of the concerned SLDs depends strongly on injection current and, moreover, can change significantly in long-term operation. To our knowledge, there are no works devoted to this aspect of broad-band SLDs reliability.The aim of this work was to research experimentally the changes of power and spectrum characteristics of SLD-37 devices, and to develop a method of estimating their lifetime.There is a lot of requirements for OCT SLDs. The injection current I is limited from above, output power P has both minimum and maximum, and so does the median 978-1-61284-813-6/11/$26.00 ©2011 IEEE 1 wavelength 'A.. Taking into account the double-humped spectrum shape, spectral flatness SF is limited also. Spectral ripple, or Fabry-Perot modulation depth, is also limited from above, while bandwidth 11'A. must exceed the minimum value.Specific challenges appear around 11'A. because of strong dependence of spectrum shape on injection current (see fig. 1a). If injections current are low enough, superluminescence is determined by transitions from fundamental state only, so the spectrum shape is bell-like. Short-wavelength second maximum, corresponding to transitions from 15t excited state, appears when we raise the current. When the current reaches some specific value 10, spectral maxima become equalized (l1S=O) and 11'A. reaches its maximum value. If the current is increased more, second maximum prevails. Fig. 1 b depicts the dependence of bandwidth on inequality of spectral maxima. It seems obvious that i...

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“…4a). For 22 out of 27 investigated PEWs, medium "spectral" lifetime is shorter than "power" one, determined by (1) or (2). For most of them, Tp is several times greater than TS.…”

mentioning

confidence: 86%

“…These SLDs are based on SQW (GaAl)As/GaAs SC DH [2]. Their active channel is a traditional single transverse mode 4 flm-width ridge waveguide.…”

mentioning

confidence: 99%

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Changes in output characteristics of broad-band superluminescent diodes in the process of long-term operation

Андреева¹,

Il'chenko²,

Kostin³

et al. 2011

2011 11th International Conference on Laser and Fiber-Optical Networks Modeling (LFNM)

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“…In the past years, various structures of SLDs that emit at 0.8 [5][6][7][8] , 1.3 [9][10][11][12][13][14][15][16] , and 1.5 μm [17][18][19][20] wavelengths have been reported. In general, SLDs requirements are high-output power, efficient coupling into single-mode fibers, and suppression of lasing due to the Fabry-Perot mode under high-output power operation.…”

Section: Introductionmentioning

confidence: 99%

“…In general, SLDs requirements are high-output power, efficient coupling into single-mode fibers, and suppression of lasing due to the Fabry-Perot mode under high-output power operation. Several methods have been used to suppress lasing, such as a antireflection coating at one or two facets [5,6,11] , tilting the stripe with respect to the facets [6,7,14] , bending the stripe near the output facet or the rear facet [11,12,15,17] , window buried structure, and an unpumped absorbing region [5,8,9,10,13,14,16,18,19] .…”

Section: Introductionmentioning

confidence: 99%

High performance 1.3 μm InGaAsN superluminescent diodes

Zhang

et al. 2008

Sci. China Ser. E-Technol. Sci.

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High performance 1.3 μm InGaAsN superluminescent diodes (SLDs) were fabricated with Schottky contact. The structure was grown by metal organic chemical vapor deposition (MOCVD). Output power of 3 mW was obtained in continuous wave (CW) mode at room temperature. The full width at half maximum (FWHM) of the emission spectrum was 30 nm. The devices operated up to 100℃.InGaAsN, superluminescent diodes, Schottky contact

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Optical Coherence Tomography

Fercher¹

2000

Encyclopedia of Analytical Chemistry

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Optical coherence tomography (OCT) is a technique with which to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light detected by partial coherence interferometry (PCI) is used to synthesize the tomographic image coded in false colors. A prerequisite of this technique is a low time‐coherent but high space‐coherent light source, usually a superluminescent diode or a multimode semiconductor laser. This limits the wavelengths to the red and near‐infrared (NIR) region from about 600 nm to 1300 nm, the so‐called therapeutic window, where absorption (μ a ≈ 0.01 mm −1 ) is small enough. Transverse resolution in OCT is diffraction limited, as in conventional imaging; depth resolution is limited by the coherence length of the light. Both figures are of the order of micrometers. Velocity resolution is of the order of 0.1 mm s −1 . A few instruments are commercially available. At present, OCT is mainly used in the medical field, in particular in ophthalmology. Owing to the high transmissivity of ocular media, the depth penetration is considerable. Corresponding applications in dermatology are somewhat hindered by the strong scattering of epidermic tissue (μ s ≈ 10 2 mm −1 ). As OCT provides images with a resolution comparable to conventional histology, but in real time, it can be used as a biopsy technique in a wide range of biological systems to detect diseases. These include the tomographic imaging of the internal microstructure of in vitro atherosclerotic plaques, the tomographic real‐time diagnostics for intraoperative monitoring, and in microsurgical intervention. Optical biopsy based on OCT also provides diagnostic information by differentiating the architectural morphology of urological tissue, gastrointestinal tissue, and respiratory tissue.

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(GaAl)As SQW superluminescent diodes with extremely low coherence length

Cited by 42 publications

References 4 publications

Changes in output characteristics of broad-band superluminescent diodes in the process of long-term operation

Changes in output characteristics of broad-band superluminescent diodes in the process of long-term operation

High performance 1.3 μm InGaAsN superluminescent diodes

Optical Coherence Tomography

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