Showing papers on "Fiber Bragg grating published in 1977"
TL;DR: This paper considers various multiplex system designs that might be used with multimode fiber transmission systems, and the required multiplexer size and material properties are calculated as functions of the basic parameters of the fiber system.
Abstract: The capacity of optical fiber transmission systems could be increased by multiplexing several signals at different wavelengths on each fiber. This paper considers various multiplex system designs that might be used with multimode fiber transmission systems. In each case, the required multiplexer size and material properties are calculated as functions of the basic parameters of the fiber system. For fiber systems of the type currently being tested, a compact (~2 mm in diameter × 1 cm long), rugged, three-channel multiplexer could be constructed using a blazed plane reflection grating and graded-refractive-index (GRIN) optics; and it appears that such devices could be produced using available materials and technology. Multiplexers using thick gratings or multilayer dielectric filters are larger, more complicated, and require materials at the very edge of available technology. Multiplexers using a multiple thick grating or hologram could be even smaller than the blazed-grating devices, but materials having the required characteristics have not been demonstrated.
164 citations
TL;DR: The interference pattern of two laser beams induces periodical variations of the optical properties of matter (refractive index and absorption coefficient). Induced grating structures have been observed in absorbing liquids and solids, plasmas, laser materials, dye solutions and semiconductors as discussed by the authors.
Abstract: The interference pattern of two laser beams induces periodical variations of the optical properties of matter (refractive index and absorption coefficient). Induced grating structures have been observed in absorbing liquids and solids, plasmas, laser materials, dye solutions and semiconductors. These gratings have been applied to thermal diffusion measurements, excitation of high frequency normal and second sound waves, determination of electronic lifetimes, distributed feedback lasers and real-time holography. The literature on transient grating materials and applications is surveyed.
121 citations
TL;DR: In this paper, an analytic expression for the Bragg diffraction of a Gaussian probe beam by a weak crossed-Gaussian volume grating was derived, and the grating itself was assumed to have been created by two other Gaussian excitation beams intersecting in a nonlinear medium.
Abstract: An analytic expression is derived for the Bragg diffraction of a Gaussian probe beam by a weak crossed-Gaussian volume grating. The volume grating itself is assumed to have been created by two other Gaussian excitation beams intersecting in a nonlinear medium.
84 citations
Patent•
08 Nov 1977TL;DR: In this paper, a laser-to-fiber coupler is constructed by an optical waveguide arranged between a semiconductor laser and a transmitting optical fiber through which an optical beam emanating from the laser is transmitted in order to reduce the amount of a reflection beam from the optical fiber, which is injected into the active layer of the laser.
Abstract: A laser-to-fiber coupler is constructed by an optical waveguide arranged between a semiconductor laser and a transmitting optical fiber through which an optical beam emanating from the laser is transmitted in order to reduce the amount of a reflection beam from the optical fiber, which is injected into the active layer of the semiconductor laser. The waveguide is made by an optical fiber of which at least one of core radius or numerical aperture (N.A.) is smaller than those of the transmitting optical fiber.
71 citations
TL;DR: In this paper, high collimated laser beams have been observed to be coupled out by second-order Bragg scattering from GaAs distributed Bragg reflector laser diodes.
Abstract: Highly collimated laser beams have been observed to be coupled out by second‐order Bragg scattering from GaAs distributed Bragg reflector lasers. The beams are perpendicular to the waveguide plane and have an angular width of less than 1°. The diodes have a separate confinement structure and operate at room temperature with thresholds as low as 1.4 kA/cm2.
26 citations
TL;DR: In this article, the gain of a ring and a Fabry-Perot resonator with ring and ring-perot resonators respectively is calculated for a ring laser with a single mode in order to achieve stable bidirectional operation.
Abstract: The gain calculated for a laser with ring and Fabry-Perot resonators respectively is given in a general formulation which shows clearly the influence of the spatially inhomogeneous saturation due to the standing wave pattern and the resulting Bragg scattering. When selecting a single mode in a Fabry-Perot resonator, the losses necessary to quench the modes are equal to those losses which the selected mode suffers due to the self-induced Bragg grating in the active medium. In a unidirectional ring laser, the losses only need exceed the gain of additional separate gain reservoirs of the modes. Also possible reasons are dealt with which cause stable bidirectional operation in a ring laser with homogeneously broadened gain.
14 citations
TL;DR: The frequency spectrum of a continuous wave fiber-optic Raman laser is measured and observed to consist of several discrete lines covering a 3-nm spectral range, and degradation of the fiber has been reduced in the later devices.
Abstract: The frequency spectrum of a continuous wave fiber-optic Raman laser is measured and observed to consist of several discrete lines covering a 3-nm spectral range. The output of the laser also contains damped transients which are attributed to strong pump-depletion effects in the fiber. Previously observed degradation of the fiber has been reduced in the later devices.
10 citations
TL;DR: In this article, a slitless optical-fiber laser-Raman spectrometer has been developed that employs a single f/3 concave holographic diffraction grating, which produces a straight focal line, instead of a curve, resulting in accurate focussing from 480 to 650 nm, with linear scanning.
Abstract: A slitless optical-fiber laser-Raman spectrometer has been developed that employs a single f/3 concave holographic diffraction grating. The exit end of an optical fiber is positioned at the grating focus, and the divergent excitation and Raman radiation are then dispersed and refocussed. Detection is accomplished by translating an exit slit and photomultiplier tube along the focal line. A moveable solid-core optical fiber that transmits light to a fixed photomultiplier tube may also be used. The holographic grating produces a straight focal line, instead of a curve, resulting in accurate focussing from 480 to 650 nm, with linear scanning. The low f-number grating was used to accommodate high numerical aperture optical fibers without loss of light. A comparison between the present spectrometer with a 55m fused silica fiber and a Jarrell-Ash Czerny-Turner single monochromator using a 1-cm bulk sample indicates a signal/noise improvement by a factor of 137 for the very weak two-phonon band from fused silica near 1600 cm−1.
10 citations
TL;DR: This work reported on the impulse response of such a fiber excited by a Lambertian source, which involved a double summation and the parabolic cylinder function.
Abstract: where n is the refractive index of the core, c is the velocity of light in a vacuum, D is the mode independent coupling coefficient, A is the second-order loss coefficient, and z is the fiber length. Recently we reported on the impulse response of such a fiber excited by a Lambertian source. The response involved a double summation and the parabolic cylinder function. Provided that (AD)z > 1, an assumption that was used to
4 citations
TL;DR: In this article, it was shown that a laser beam retains its spatial coherence during passage through a single-mode fiber waveguide 150 m long, and two types of laser interferometer utilizing such a waveguide were described.
Abstract: Experimental evidence is given that a laser beam retains its spatial coherence during passage through a single-mode fiber waveguide 150 m long. A description is given of two types of laser interferometer utilizing such a waveguide.
2 citations
01 Aug 1977
TL;DR: In this paper, experiments were conducted to show that circularly polarized laser light provides improved visibility through mist, and the results showed that the light provided better visibility than traditional laser light.
Abstract: Results of experiments are described which show that circularly polarized laser light provides improved visibility through mist.
01 Jan 1977
TL;DR: In this article, the wavelength of a single-mode cw laser can be accurately measured with the help of a fringe-counting traveling Michelson interferometer, but unfortunately this method cannot easily be extended to pulsed lasers, such as the widely used nitrogen-pumped dye laser systems.
Abstract: The wavelength of a single-mode cw laser can be accurately measured with the help of a fringe-counting traveling Michelson interferometer, but unfortunately this method cannot easily be extended to pulsed lasers, such as the widely used nitrogen-pumped dye laser systems. Today, most laboratories seem to employ conventional grating spectrographs to measure the wavelength of pulsed lasers. The resolution of such instruments can actually be quite sufficient in view of the typical larger bandwidth of pulsed lasers. But because of mechanical imperfections of the grating drive, the available digital wavelength readout can only be used for rough estimates, and any absolute wavelength measurement with the help of spectral lamps and wavelength catalogs is at best tedious.