Showing papers on "Fiber laser published in 1979"
TL;DR: Raman and Brillouin gains in fibers are a factor of 2 higher if linear polarization is maintained as mentioned in this paper.Birefringent single-mode fibers are used to demonstrate this gain difference.
Abstract: Raman and Brillouin gains in fibers are a factor of 2 higher if linear polarization is maintained. Birefringent single-mode fibers are used to demonstrate this gain difference. Threshold powers of 200 mW have been achieved in Raman oscillators.
285 citations
TL;DR: A fiber-optic gyro is described that employs closed-loop phase compensation and preliminary experimental results are reported of the sensing of rotation rates down to 0.5 degrees /sec for a 135-mm-radius, 100-m-length fiber coil.
Abstract: A fiber-optic gyro is described that employs closed-loop phase compensation. Preliminary experimental results are reported of the sensing of rotation rates down to 0.5 degrees /sec for a 135-mm-radius, 100-m-length fiber coil.
121 citations
TL;DR: In this paper, a theory for Raman fiber laser oscillators is presented and the Stokes output and residual pump power are derived from a knowledge of the input pump power and the fiber characteristics.
Abstract: A theory for Raman fiber laser oscillators is presented. The Stokes output and the residual pump power are shown to be calculable from a knowledge of the input pump power and the fiber characteristics. The evolution of the pump and the Stokes waves along the fiber are also obtained. The threshold pump power and the oscillation condition are considered. Pump depletion is incorporated in the analysis and is shown to be the dominant saturation effect present in a Raman fiber laser.
83 citations
TL;DR: In this article, threshold characteristics of stripe-geometry InGaAsP/InP double-heterostructure injection lasers have been analytically derived as a function of active layer thickness and stripe width.
Abstract: Threshold characteristics of stripe-geometry InGaAsP/InP double-heterostructure injection lasers have been analytically derived as a function of active layer thickness and stripe width. The effects of stripe width, refractive index in the active layer, diffusion of injected carriers, carrier lifetime, absorption loss in the cladding layer, gain coefficient, and cavity length on the optimum thickness of the active layer which gives minimum threshold or on threshold current density were studied. These lasers were fabricated on
53 citations
TL;DR: The use of a mode-locked color-center laser is described to demonstrate nearly distortionless propagation of ~5-psec-wide, Fourier-transform-limited pulses, at or near the zero-dispersion wavelength, in two fused-silica, singlemode fibers of 0.76- and 2.5-km length.
Abstract: We describe the use of a mode-locked color-center laser to demonstrate nearly distortionless propagation of ~5-psec-wide, Fourier-transform-limited pulses, at or near the zero-dispersion wavelength, in two fused-silica, singlemode fibers of 0.76- and 2.5-km length, respectively. We also report the detection of sharply defined cross correlations between pulses directly from the laser and those had been delayed many microseconds by passage through a fiber.
46 citations
TL;DR: In this article, a self-contained laser-LED package has been demonstrated in continuous room-temperature operation with a pump diode current of ∼ 75 mA and laser threshold at ∼ 10 mA pump current.
Abstract: Lasers have been made from Nd: YAG single crystals grown directly in the form of fibers. These fibers, 50 to 80 μm in diameter and 0.5 cm long, were pumped at 0.8 μm wavelength by a single AlGaAs LED. One milliwatt output power, plane polarized in a single mode at 1.064 μm wavelength, has been achieved in continuous room-temperature operation, and a self-contained laser-LED package has been demonstrated. Construction and operation of the devices are described. Improvement by a factor of two in operating efficiency using straightforward techniques is predicted to yield 1 mW output at a pump diode current of ∼ 75 mA and laser threshold at ∼ 10 mA pump current.
41 citations
TL;DR: In this article, a flash lamp pumped dye laser with a ring cavity was injected with the light beam coming from a stabilized singlemode c.w. dye laser, and the light emitted by the pulsed laser was analyzed either by a Fabry Perot etalon, or by producing a Doppler-free two-photon transition.
26 citations
TL;DR: In this article, the authors reported that the lasing spectra of semiconductor lasers coupled to optical fibers with end-butt joint show nearly random lasing at wavelengths decided only by the fiber length.
Abstract: This paper reports that lasing spectra of semiconductor lasers coupled to optical fibers with end-butt joint show nearly random lasing at wavelengths decided only by the fiber length. Wavelength spacing is found to coincide with the resonance wavelength spacing of the optical cavity formed by the optical fiber.
25 citations
TL;DR: In this paper, the polarization characteristics in cabled single mode fibers were studied using 4.15 km long fibers and a single frequency AlGaAs double-heterostructure laser, interference fringes were observed.
Abstract: Polarization characteristics in cabled single mode fibers were studied. By using 4.15 km long fibers and a single frequency AlGaAs double-heterostructure laser, interference fringes were observed.
24 citations
Patent•
22 Oct 1979TL;DR: In this article, a method to prepare and coat an optical fiber with Si 3 ub.4 is described, which hermetically seals the fiber and enhances and maintains the mechanical strength of the fiber.
Abstract: Disclosed is a method to prepare and coat an optical fiber with Si 3 ub.4. The Si 3 N 4 is synthesized from SiF 4 +NH 3 and/or SiH 4 +NF 3 by laser photochemical reaction (LPR) techniques in a controlled atmosphere chamber. The silicon fiber which is a representative optical fiber is drawn from a preform at about 2000° C. in a standard fiber drawing furnace. Immediately after drawing of fiber, the fiber is passed through a chamber with a controlled atmosphere containing SiX 4 and NX 3 gases, wherein X equals hydrogen or fluorine. A laser is used to irradiate the atmosphere and the Si 3 N 4 is coated on the optical fiber to a thickness of about 0.02-0.20 micrometer which hermetically seals the fiber and enhances and maintains the mechanical strength thereof.
24 citations
TL;DR: Dithering the laser's operating point by means of a high-frequency current (>2 GHz) has been found greatly to reduce modal noise.
Abstract: Modal noise, which can cause severe distortion in signals transmitted by fiber optics, is an interference effect that is made more severe by the narrow spectral width of single-mode lasers. The linearity of these devices may be totally obscured after the optical signal has passed through the connectors and fiber lengths of a practical signal system. Dithering the laser's operating point by means of a high-frequency current (>2 GHz) has been found greatly to reduce modal noise.
01 Oct 1979
TL;DR: In this article, the light from a semiconductor laser is coupled efficiently into a tapered hemispherical-end optical fiber obtained by drawing in an arc discharge, achieving a maximum coupling efficiency of 83 percent for the graded index fiber having a 60µm core diameter.
Abstract: The light from a semiconductor laser is coupled efficiently into a tapered hemispherical-end optical fiber obtained by drawing in an arc discharge. The maximum coupling efficiency of 83 percent is achieved for the graded index fiber having a 60-µm core diameter. Permissible transverse displacement for a 1-dB decrease of coupling is about 19 µm.
TL;DR: In this article, GaInAsP/InP distributed Bragg reflector (DBR) with a first-order grating was demonstrated experimentally for the first time at a wavelength of 13 μm, single longitudinal mode oscillation was obtained at low temperature, and the temperature dependence of the lasing wavelength was 07-08 A/deg.
Abstract: GaInAsP/InP distributed Bragg reflector (DBR) lasers with a first-order grating were demonstrated experimentally for the first time at a wavelength of 13 μm Single longitudinal mode oscillation was obtained at low temperature, and the temperature dependence of the lasing wavelength was 07-08 A/deg The equivalent refractive index of GaInAsP at the lasing wavelength of 13 μm was 350 at 186 K
TL;DR: The air bubbles sometimes observed at the splicing point in fusion splices were avoided by preparing fiber ends with a laser-scribing method.
Abstract: Mirror-finished end preparation and low-loss splicing of silica fiber arrays by means of a CO(2) laser are demonstrated. Eight-fiber linear arrays of multimode fibers with 60-microm core diam and 150-microm outer diam were laser scribed and fractured, then butted and spliced with 3.0-W laser power output, 1.0-mm beam-spot diam, and 15-microm/sec fiber array driving speed. Average splice losses for 20x splicings (160 splices) in step- and graded-index fibers were 0.12 db and 0.10 dB, respectively. The air bubbles sometimes observed at the splicing point in fusion splices were avoided by preparing fiber ends with a laser-scribing method.
TL;DR: In this article, the group delay time difference between LP 01 and LP 11 modes has been measured in a step-index type optical fiber over a two-mode region, and the measured results revealed that there exists a wavelength at which the groups delay times of the two modes are coincident.
Abstract: Group delay time difference between LP 01 and LP 11 modes has been measured in a step-index type optical fiber over a two-mode region. The measured results have revealed that there exists a wavelength at which the group delay times of the two modes are coincident.
TL;DR: Results show that tap-controlled transmitters have output-power stability within +/-2% (+/-0.1 dB) over a 1000-h test period, this being an order of magnitude improvement compared with the earlier scheme of control.
Abstract: Several laser transmitters assembled for 44.736-Mb/sec lightwave field experiments exhibited large, unexpected changes in output power. This problem is now identified with laser front-to-back mirror mistracking and its effect on the back-mirror-monitoring scheme used for feedback control of the laser. To correct this problem, an optical-fiber tap was developed to monitor the actual output power for feedback control. This paper describes the output power stability of five GaAlAs laser transmitters operated using this optical tap for feedback control. Results show that tap-controlled transmitters have output-power stability within ±2% (±0.1 dB) over a 1000-h test period, this being an order of magnitude improvement compared with the earlier scheme of control.
TL;DR: Optical fibers with ends polished 45 degrees to the axis and mounted transversely with respect to injection lasers are shown to have laser-fiber coupling efficiencies comparable with the commonly used hemispherically ended fibers.
Abstract: Optical fibers with ends polished 45° to the axis and mounted transversely with respect to injection lasers are shown to have laser–fiber coupling efficiencies comparable with the commonly used hemispherically ended fibers (≈50%). The transverse scheme has the advantage that photodiodes can be mounted to monitor emission from the same mirror of the laser as that to which the fiber is coupled, thus permitting the output power from the fiber to be feedback-stabilized even if the laser develops front/back mirror mistracking. This is accomplished without the customary use of optical taps or additional lenses and mirrors.
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TL;DR: A fiber laser plate, consisting of many fiber lasers in a form similar to an ordinary optical fiber plate, is described, which can emit a laser light image corresponding to a 2-D transparency when end-pumped.
Abstract: In this paper a fiber laser plate, consisting of many fiber lasers in a form similar to an ordinary optical fiber plate, is described. The fiber laser plate, when end-pumped, can emit a laser light image corresponding to a 2-D transparency. The abrupt change of output intensity with excitation energy shows that the plate is attractive as an optical threshold device.
Patent•
15 Nov 1979
TL;DR: In this article, a core having a high refractive index and a clad having a lower than the index of the core are formed by SiO2 and P2O5 having high purity.
Abstract: PURPOSE:To decrease light loss by extremely diminishing transition metal impurities and residual OH radicals. CONSTITUTION:A core having a high refractive index and a clad having a refractive index lower than the index of the core are formed by SiO2 and P2O5 having high purity. The core contains P2O5 in 10mol%. Light loss can be reduced by using an optical fiber formed in this manner as a laser medium for a fiber raman laser.
TL;DR: Comparison between experimental measurements and ray interference computations shows that the cross section of the fiber under test is neither circular nor elliptical, but can be described with good approximation by a limited Fourier series, the coefficients of which are estimated.
Abstract: Study of the light scattered from an unclad optical fiber illuminated by a laser beam perpendicular to its axis gives a valuation of little defects of the fiber cross section. The shifts of some bright fringes that occur when the fiber is rotated are observed. Comparison between experimental measurements and ray interference computations shows that the cross section of the fiber under test is neither circular nor elliptical, but can be described with good approximation by a limited Fourier series, the coefficients of which are estimated.
TL;DR: In this article, the authors developed a long-distance, high-data-rate heterojunction laser with emission wavelengths beyond 1 ptm, which is suitable for fiber optic data systems of present interest.
Abstract: Reductions in power consumption and improvements in reliability have made AlGaAs stripe-contact heterojunction lasers well suited for many fiber optic data systems of present interest. Although the beam pattern of some of these lasers is in the form of a stable single lobe, instabilities in the lateral direction are often observed, and require further attention for fibers with small acceptance angles. For long-distance, high-data-rate fiber systems, heterojunction lasers with emission wavelengths beyond 1 ptm are being developed. Such lasers of InGaAsP/InP have many attractive properties, but suffer from carrier leakage at short wavelengths (1.0-1.2 µm) and elevated temperatures.
TL;DR: In this paper, the influence of the misalignment between the axes of a semiconductor laser beam and of multimode or single-mode fibers on the efficiency of coupling of radiation into the fibers was analyzed.
Abstract: A theoretical analysis is made of the influence of the misalignment between the axes of a semiconductor laser beam and of multimode or single-mode fibers on the efficiency of coupling of radiation into the fibers Two cases are considered: a direct contact between a laser and a fiber, and an indirect contact with a matching element in the form of a fiber segment with a square-law variation of the refractive index
01 Jan 1979
TL;DR: In this paper, the GaAs and AlGaAs heterojunction diodes in which the most efficient diode operation has been obtained at room temperature, including CW laser operation with the emission of tens of milliwatts of power.
Abstract: The laser diode and the more familiar light-emitting diode (LED) are similar in that both consist basically of a p-n junction in which radiative recombination occurs under forward bias by the injection of carriers into a suitably designed region of the diode. Large differences exist, however, in the specific device design and materials needed to obtain efficient lasing at room temperature. This chapter will be concerned mostly with GaAs and AlGaAs heterojunction diodes in which the most efficient diode operation has been obtained at room temperature, including CW laser operation with the emission of tens of milliwatts of power. These diodes emit radiation in the 8000–9000 A spectral region, depending on the alloy composition, a region well-suited for low loss (<10 dB/km) optical fibers. A second favorable transmission window is the 1.0 to 1.2 µm spectral range which requires alloys of InGaAs, InAsP, InGaAsP or similar low band-gap alloys. Reduced fiber attenuation and pulse dispersion are obtained at these longer wavelengths.
06 Mar 1979
TL;DR: In this paper, the integration of fiber optics and integrated circuits technologies poses a new challenge for IC packaging because a package must include electronic components, electro-optical interfaces, electrical connections, and optical connections.
Abstract: Optical fibers are of potential use in data links for computers and switching systems.1 As in the case of integrated circuits, the cost and size of the electro-optical interfaces can be decreased by using a batch fabrication process, by having several optical devices sharing an identical package, and by placing several optical devices and integrated circuits together in a single package. This integration of fiber optics and integrated circuits technologies poses a new challenge for IC packaging because a package must include electronic components, electro-optical interfaces, electrical connections, and optical connections.