Showing papers on "Fiber laser published in 1983"
TL;DR: The narrowing of pulses to widths as small as 0.26 psec by various lengths, short relative to the soliton period, of single-mode, low-loss optical fiber is reported to be in at least semiquantitative agreement with prediction based on the nonlinear Schrödinger equation.
Abstract: We report the narrowing of pulses, initially 7 psec FWHM, to widths as small as 0.26 psec by various lengths, short relative to the soliton period, of single-mode, low-loss optical fiber. Since the ~1.5-μm wavelength lies in the region of negative group-velocity dispersion (∂νg/∂λ 10) soliton number. We show these results to be in at least semiquantitative agreement with prediction based on the nonlinear Schrodinger equation.
382 citations
TL;DR: In this article, the authors discuss the possibility for semiconductor laser amplifiers to be used in a single-mode fiber communication system, and derive the power budget improvement due to the insertion of a laser amplifier in a digital optical communication system.
Abstract: The recent advent of very low loss single mode optical fibers (< 0.2 dB/km at the 1.55μπι wavelength) opens the possibility for very long distance, high information bandwidth (^1 Gbit/s) communication systems, as transoceanic cable links or trunk networks. With such fibers, especially when chromatic dispersion is negligible, the range is only limited by attenuation, so there would be no need for complete signal regeneration (pulse shaping, timing, etc...). In these conditions, direct light amplifiers would be very attractive as \"on-line\" amplifiers as an alternative to sophisticated optoelectronic repeaters; they could also be used in a receiver as low noise preamplifiers, in combination with a pinphotodiode, especially at the 1.3 ... 1.55 μη wavelength, where avalanche photodiodes (APD) are more \"noisy\" than silicon APDs. It is our purpose to discuss the possibility for semiconductor laser amplifiers to be used in a single mode fiber communication system. We shall first derive the power budget improvement due to the insertion of a laser amplifier in a digital optical communication system. A review of semiconductor laser amplifiers (SCLA) characteristics of the traveling-wave type (TW), Fabry-Perot type (FP) and injection locked laser type (ILL) will then be presented, with emphasis on recent experimental results. Finally, possible applications of these devices in single mode fiber communication systems will be discussed. 2 Noise characteristics of a laser amplifier in an optical communication system
138 citations
TL;DR: In this paper, a condition for the single-mode operation of a rapidly modulated DBR laser, called a "dynamic-singlemode laser," and the dynamic spectral width were theoretically presented.
Abstract: The theoretical bases and the experimental results of the dynamic behavior of 1.5-1.6 \mu m GaInAsP/InP dynamic-single-mode (DSM) lasers with distributed Bragg reflector (DBR) are given. A condition for the single-mode operation of a rapidly modulated DBR laser, called a "dynamic-single-mode laser," and the dynamic spectral width were theoretically presented. Experimentally, buried-heterostructure distributed-Bragg-reflector integrated-twin-guide (BH-DBR-ITG) and buried-heterostructure butt-jointed-built-in distributed-Bragg-reflector (BH-BJB-DBR) lasers emitting at the wavelength of 1.5-1.6 \mu m were directly modulated up to 3 GHz, and the stable single-mode operations were obtained in both types of lasers. The dynamic spectral width at the worst modulation condition was measured to be 0.27 nm, which was about \frac{1}{35} times smaller than that of conventional lasers.
103 citations
Patent•
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TL;DR: A Brillouin ring laser comprises a fiber optic resonator formed from a loop (14) of fiber optic material (10) and a fiber-optic directional coupler (20) for optically closing the loop.
Abstract: A Brillouin ring laser comprises a fiber optic resonator formed from a loop (14) of fiber optic material (10) and a fiber optic directional coupler (20) for optically closing the loop (14).
71 citations
TL;DR: Third-harmonic generation and three-wave sum-frequency light generation in a short-length elliptical-core optical fiber pumped by pulses from a Q-switched and mode-locked Nd:YAG laser, operating at 1.064microm, have been observed in the 355-385-nm spectral range.
Abstract: Third-harmonic generation and three-wave sum-frequency light generation in a short-length elliptical-core optical fiber pumped by pulses from a Q-switched and mode-locked Nd:YAG laser, operating at 1.064 μm, have been observed in the 355–385-nm spectral range. In particular, the third harmonics of the pump (λ0 = 1.064 μm, λ0/3 = 354.7 nm) and of the first Raman Stokes (λ1 = 1.116 μm λ0/3 = 372.0 nm) lines have been obtained with 5-kW peak power of the laser pulses.
56 citations
TL;DR: It is concluded that a tapered fiber end with a large working distance reduces the influence on the laser's performance, and the influence of various fiber faces on laser power and wavelength stability is presented.
Abstract: The coupling of CSP lasers to single-mode fibers with different coupling structures made on the fiber face is investigated. In this case easy to make coupling arrangements such as tapers and microlenses, result in a high launching efficiency (∼2-dB loss), in contrast to launching from gain-guided lasers with strong astigmatism and a broader far-field pattern. Index-guiding lasers exhibit, however, a higher sensitivity to optical feedback. Laser output power and wavelength are changed due to reflections from the fiber tip. Critical distances exist which lead to a highly unstable laser spectrum. A comparison of the influence of various fiber faces on laser power and wavelength stability is presented. It is concluded that a tapered fiber end with a large working distance reduces the influence on the laser's performance.
49 citations
TL;DR: Efficient stimulated Raman scattering at 342 nm was obtained in multimode fused-silica fibers pumped by a conventional N(2) laser and the intensity-dependent absorption coefficient and Raman-gain coefficient were determined.
Abstract: Efficient stimulated Raman scattering at 342 nm was obtained in multimode fused-silica fibers pumped by a conventional N2 laser. The values of the intensity-dependent absorption coefficient and the Raman-gain coefficient were determined: α1, = 3.3×10-6 cm/MW and γ = 2.9 × 10-11 cm/W, respectively. Raman scattering by the OH impurities in the fiber was observed at 385 nm.
23 citations
TL;DR: Amplification of continuous laser radiation propagating in a monomode optical fiber was obtained by evanescent field coupling within a pumped dye solution deposited in the neighborhood of the fiber core using He-Ne radiation and DCM dye solution.
Abstract: Amplification of continuous laser radiation propagating in a monomode optical fiber was obtained by evanescent field coupling within a pumped dye solution deposited in the neighborhood of the fiber core. A factor-of-25 signal gain was recorded for 632.8-nm He–Ne radiation and DCM dye solution.
17 citations
TL;DR: The direct analysis in the time domain of the fluctuations of a signal propagating in a fiber-optic link in the presence of an imperfect connector makes it possible to formalize in a simple manner the description of its statistical properties.
Abstract: The direct analysis in the time domain of the fluctuations of a signal propagating in a fiber-optic link in the presence of an imperfect connector makes it possible to formalize in a simple manner the description of its statistical properties. This permits, in particular, the clarification of the role played by the various time scales involved in the problem (coherence time of the fiber-exciting source, fiber modal delay, detector response time, etc.) in evaluating the statistical averages. The formalism includes in a straightforward way the case of simultaneous excitation of the fiber by more than one source. This last circumstance is expedient for checking the beneficial effect on modal noise derived from exciting the fiber with N laser sources.
14 citations
TL;DR: Theoretical and experimental results are described for a new optical coupler which consists of two laser diodes, two GRIN spherical rod lenses, a polarizing filter, and a single-mode fiber that employs laser diode polarization characteristics for an optical submarine transmission laser redundancy system.
Abstract: Theoretical and experimental results are described for a new optical coupler which consists of two laser diodes, two GRIN spherical rod lenses, a polarizing filter, and a single-mode fiber, and which employs laser diode polarization characteristics for an optical submarine transmission laser redundancy system. This optical coupler has two channels at 1.3 μm wavelength. Optical coupler loss values, which include coupling loss, polarization loss, and assembly loss, are 4.9 dB for one laser diode and 5.2 dB for another laser diode. Such loss values are almost the same as the conventional laser diode module loss for a single-mode fiber. This paper describes in detail a laser redundancy system in an optical submarine transmission system, structure and characteristics of an optical coupler, and experimental results on a high bit rate long-haul transmission system using the proposed optical coupler.
12 citations
TL;DR: In this article, pulsed laser illumination may be used to suppress the ambient motion related instabilities associated with the application of coherent multimode optical fiber image bundles to the recording of remote holograms.
Abstract: This study demonstrates that pulsed laser illumination may be used to suppress the ambient motion related instabilities associated with the application of coherent multimode optical fiber image bundles to the recording of remote holograms.
TL;DR: It is confirmed that the launching efficiency eta from semiconductor lasers into multimode fibers is much greater than TE and HE compared with PE, with TE being the most efficient.
Abstract: The plane ends (PE) of various multimode optical fibers have been transformed into (a) hemispherical ends (HE) and (b) taper-with-hemisphere ends (TE) by using a microtorch and also a CO2 laser for HE only. We confirmed that the launching efficiency η from semiconductor lasers into multimode fibers is much greater than TE and HE compared with PE, with TE being the most efficient. A rigorous comparison between these three launching arrangements is reported here for the first time together with detailed analysis of similar published work. The effect of various misalignments is also investigated and compared for the three fiber terminations.
TL;DR: In this paper, the use of high-power continuous wave and pulsed laser (Nd3+:YAG, Argon ion, CO 2, excimer, etc.) and optical waveguides for delivering high powers in the ultraviolet (UV), the visible, and the infrared (IR) regions.
Abstract: For various material-processing applications with robots we propose the use of high-power continuous wave and pulsed lasers (Nd3+:YAG, Argon ion, CO 2 , excimer, etc.) and optical waveguides for delivering high powers in the ultraviolet (UV), the visible, and the infrared (IR) regions. We discuss the use of low-loss silica glass fiber waveguides for delivering high-power laser beam in the UV to near-IR spectral region (0.3 to 2 μm), and the use of a waveguiding articulating arm for delivering high-power laser beam in the long IR (2 to 10 μm). We also describe a design for fitting a CO 2 laser waveguiding arm to the robotic arm, as well as the advantages of using optical waveguides for high-power laser delivery to robots for material processing.
TL;DR: It is shown how erroneous results can be obtained when considering only the stimulated emission of the lasers in calculating eta, and the dependence of eta on axial, lateral, and angular misalignments is investigated and explained qualitatively with ray optics.
Abstract: A systematic and detailed study of launching light from semiconductor lasers into plane-ended multimode optical fibers has been carried out--we believe for the first time. Three different semiconductor lasers and four multimode fibers having numerical apertures in the 0.16-0.40 range were used. Simple theoretical models developed for the launching efficiency eta give good agreement with experimental results. We show how erroneous results can be obtained when considering only the stimulated emission of the lasers in calculating eta. The dependence of eta on axial, lateral, and angular misalignments is also investigated and explained qualitatively with ray optics.
TL;DR: In this paper, a low-loss graded-index multimode fiber with a length up to 770 m was used as the laser cavity and the mode pattern of the output beam from a mirror coated at the fiber end face exhibited typical speckle pattern.
Abstract: Continuous-wave oscillation characteristics of a 106-μm Nd3+:YAG laser with a long optical-fiber resonator were investigated Output power of 27 mW was obtained for a low-loss graded-index multimode fiber 83 m in length Laser oscillations with a cavity length up to 770 m were attained by using a graded-index fiber The mode pattern of the output beam from a mirror coated at the fiber end face exhibited a typical speckle pattern A single-mode fiber with a length of 1 m was also used as the laser cavity, and a clear Gaussian beam with an output power of 1 mW was observed
TL;DR: In this paper, a compact fiber interferometer is used to stabilize the frequency fluctuations of GaAlAs laser, and the properties of the laser are determined before and after stabilization.
Abstract: A compact fiber interferometer is used to stabilize the frequency fluctuations of GaAlAs laser. The properties of the laser are determined before and after stabilization. The application of this technique to conventional interferometer demodulation schemes is discussed.
08 Nov 1983
TL;DR: In this paper, a circuit designed for direct modulation of semiconductor lasers at frequencies up to 2.5 GHz has been built in order to study the high speed modulation characteristics of injection lasers.
Abstract: A circuit designed for direct modulation of semiconductor lasers at frequencies up to 2.5 GHz has been built in order to study the high speed modulation characteristics of injection lasers. The circuit provides flat (±1.0 dB) frequency response from 20 kHz to 2.6 GHz. An integral bias T network provides a dc bias port for laser prebias. A versatile experimental mounting fixture incorporating this circuit provides thermoelectric cooling of stud mounted lasers and allows for simultaneous measurements from both laser facets. The laser can be cooled or heated and an active feedback controller holds the stud temperature to ±0.05°C. This mounting fixture and circuit were recently employed in an experimental single mode fiber communications system employing a new Bell Labs mode stabilized laser at 1.5 μm. The system set a new length record of 119 km for unrepeatered transmission at a bit rate of 420 Mb/s. Distortion free modulation of injection lasers at speeds up to 2.0 Gb/s has been achieved.
TL;DR: An analytic definition of the connection between the wedge angle and the fiber acceptance half-angle is developed, along with a formula for the minimum half-angles, and an inequality is defined for determining the bevel angle of the output end of the fiber to eliminate end reflections.
Abstract: Design and experimental data for obtuse-angled wedges used in coupled configurations of diode lasers and multimode fibers are presented. An analytic definition of the connection between the wedge angle and the fiber acceptance half-angle is developed, along with a formula for the minimum half-angle. An inequality is defined for determining the bevel angle of the output end of the fiber to eliminate end reflections. The fiber parameters are accounted for in the bevel. The formulations were tested in comparison with the performance of a coupled CDH laser system and good agreement was found in the output spectrum.
TL;DR: In this paper, the conditions of propagation of opposite waves in a ring Raman fiber laser excited by an external periodic signal whose duration is less than the time needed for a round trip in the ring resonator were analyzed.
Abstract: An analysis is made of the conditions of propagation of opposite waves in a ring Raman fiber laser excited by an external periodic signal whose duration is less than the time needed for a round trip in the ring resonator. It is shown that an allowance for nonlinear properties of the fiber gives rise to an optical nonreciprocity in respect of the opposite waves. A calculation is made of the frequency difference between the opposite waves in a ring laser as a function of the laser parameters.
TL;DR: In this paper, the authors demonstrate the possibility of error-free transmission over 100 km without repeater, by using a singlemode fiber and a laser diode with distributed feedback emitting a single longitudinal mode at the wavelength 1.5 μm.
Abstract: The paper reports an experiment which demonstrates the possibility of error-free transmission over 100 km without repeater, by using a single-mode fiber and a laser diode with distributed feedback emitting a single longitudinal mode at the wavelength 1.5 μm.
28 Feb 1983
TL;DR: To illustrate nonlinear-optical applications of germanium dioxide (GeO(2)) glass optical fibers, efficient single-pass Raman generation in a GeO( 2) fiber is demonstrated and the chromatic dispersion of high-silica glass single-mode optical fibers is measured.
Abstract: We present the first observations of efficient single-pass Raman generation in low-loss optical fibers with a Sb-doped GeO2 core. The critical peak power for 93-μm core diameter 28-m long GeO2 fiber was measured at 9 kW, nine times smaller than for SiO2 fiber.
TL;DR: In this article, the authors proposed the use of κ0 as a characteristic launching parameter which allows easy comparison of measured fiber impulse responses for two realistic excitations, first, by a gain-guided laser diode and second, by an index-guided diode.
Abstract: In the case of optimal excitation of a multimode graded-index fiber by a laser diode, the coupling efficiency κ0 between the Gaussian laser beam and the fundamental mode of the fiber describes the input mode power distribution uniquely. Using this result, fiber impulse responses are calculated for two realistic excitations, first, by a gain-guided laser diode and second, by an index-guided laser diode. Also, the commonly used uniform and stationary excitations are given for comparison. The calculations yielding these results are based on the power diffusion equations and include profile dispersion, material dispersion, mode-dependent attenuation, and mode coupling. The mode group delay times have been computed for a parabolic profile using the scalar wave equation. However, delay times for other profiles can be introduced in the calculations. As κ0 characterizes laser fiber coupling uniquely and because it can simply be measured, we propose the use of κ0 as a characteristic launching parameter which allows easy comparison of measured impulse responses.
TL;DR: In this paper, an investigation was made of the efficiency of coupling into fiber waveguides of 12-16 μ radiation emitted by a buried mesastripe InGaPAs-InP heterojunction laser.
Abstract: An investigation was made of the efficiency of coupling—into fiber waveguides—of 12–16 μ radiation emitted by a buried mesastripe InGaPAs–InP heterojunction laser The maximum power of the radiation coupled into a fiber waveguide was 16 mW in the cw regime at room temperature The coupling efficiency was 90% in the case of a multimode fiber waveguide and 36% in the case of a single-mode waveguide when matching was provided by a microlens with a radius of ~10 μ
30 Aug 1983
TL;DR: In this paper, a hemispherical microlens of appropriate focal length is fabricated at the end of the single-mode fiber to improve the mode matching of the laser and fiber fields.
Abstract: The coupling efficiency between semiconductor lasers and single mode fibres can be greatly increased if a microlens of appropriate focal length is fabricated at the end of the fibre, the reason being that the lens caneffectively improve the mode matching of the laser and fibre fields.Using simple techniques we have fabricated hemispherical microlenses at the end of fibres. Coupling efficiencies of about 50% have been achieved.The thoery used to predict the lens parameters for maximum coupling regards the lens as a 'thick lens' and shows that spherical aberration contributes to coupling loss. IntroductionMuch attention is being given to low loss single mode fibre in the field of optical communication. With their low loss and inherently wide bandwidth, monomode fibres provide a suitable long haul transmission mediumfor large capacity telecommunication systems [1].To utilise fully this capability, efficient power coupling between semiconductor laser and single mode fibre
26 Oct 1983
TL;DR: In this article, a novel method is presented for the measurement of optical fibers with diameters of 10-120 mm. The method is based on the detection of resonances in the intensity of dye laser light backscattered from a fiber in the far-field when tuning the wavelength.
Abstract: A novel method is presented for the measurement of optical fibers with diameters of 10-120 μm. The method is based on the detection of resonances in the intensity of dye laser light backscattered from a fiber in the far-field when tuning the wavelength. It has been experimentally confirmed that not only a thick (-120 μm) communication fiber produces Fabry--Perot resonances, but a thin (-13 μm) doubly-clad imaging fiber as well. The obtained accuracy is better than ± 0,1 μm. Also, the basic features of the WIRE GAUGE instrument based on laser beam scanning are shortly outlined.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
28 Nov 1983
TL;DR: In this article, a negative linear group velocity dispersion of 8m of single-mode optical fiber was used to compress pulses from optically pumped, ultrashort cavity semiconductor film lasers.
Abstract: Picosecond pulses from optically pumped, ultrashort cavity semiconductor film lasers have a large positive chirp that is not linear in time. Average chirp values are about 1 nm/psec for InGaAsP film lasers. The chirp is caused by transient change in the refractive index of the semiconductor film during the pulse due to variation of the free carrier concentration. The transient carrier concentrations of 1020 cm-3 caused by the intense picosecond pump pulses is sufficient to account for the observed chirp. For film lasers, the dominant mechanism by which the carriers affect the index of refraction is free carrier plasma refraction. The positively chirped pulses have been compressed by the negative linear group velocity dispersion of 8m of single-mode optical fiber. Pulse compression factors as large as 3.4 have been obtained. Pulses as short as 2.5 psec at 1.23 μm and 3.4 ps at 1.42 μm have been generated by this compression scheme.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Journal Article•
TL;DR: In this article, a broadband differential optical interferometer that uses an optical-fiber waveguide to transmit coherent light to a surface under inspection is discussed, where the light is coupled into two singlemode optical fibers in a stationary input optics enclosure.
Abstract: A broadband differential optical interferometer that uses an optical-fiber waveguide to transmit coherent light to a surface under inspection is discussed. Input laser light is coupled into two single-mode optical fibers in a stationary input optics enclosure. The fibers transmit the light to a small, remote detection head where it is used in a wide-band differential interferometer to detect continuous and pulsed surface-particle displacements. The effective separation between the input optics and the detection head allows simple surface scanning and probe alignment. Detection of simulated acoustic emission pulses by a prototype test unit is reported.
19 Sep 1983
Abstract: A fiber optic system consisting in its main parts of a GaAlAs laser diode, a monomode launching fiber and a fiber Fabry Perot (FFP) resonator is investigated in view of two main aspects: 1) use of the FFP as fiber optic spectrum analyzer (FOSA) with the laser diode presenting a light source of rather complex spectral behavior, and 2) application of a FFP fabricated with a birefringent fiber as a one fiber double Fabry-Perot (OFDFP) device for temperature sensing. When varying the laser injection current, temperature drift of the laser wavelength as well as instable discontinuities (mode hops) can be identified. The temperature tuned FOSA is suggested as a device for diode laser spectral performance moni-toring. The OFDFP with its double system of transmission maxima offers a scheme to determine parameter change sign and principally provides a calibration means for this type of interferometer.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.