Showing papers on "Fiber Bragg grating published in 1980"

Design of a miniature lens for semiconductor laser to single-mode fiber coupling

Abstract: A design method for a miniature optical lens tipped on a single-mode fiber end to improve power coupling from a semiconductor laser is described. The lens shapes studied are hemispherical, hemicylindrical, and hemiellipsoidal. The optimum coupling conditions and the obtained coupling efficiency are represented in terms of laser beam and fiber parameters. Preferable ranges of hemispherical and hemicylindrical lenses are classified according to the laser and fiber mode spot sizes. Fiber axis offset and tilt effects on coupling efficiency are also studied.

Fiber optic wavelength demultiplexer

Abstract: An optical fiber wavelength demultiplexer including an optical fiber mounted and adhered to a curved surface having a clad single fiber core, a planar surface extending partially into and along the fiber through the cladding, a prism mounted on the surface having a reflective diffraction grating surface positioned to receive signals from the fiber travelling in one direction and demultiplex such signals, and an array of photodiodes mounted adjacent the prism to receive the demultiplexed signals.

Fiber optic transducer for measuring current or magnetic field

Abstract: A multi-mode optical fiber is used to detect electrical currents or magnetic fields from a remote source. The optical fiber, which serves as the sensor, is composited with metal capable of conducting electricity. Optical radiation is introduced into the fiber from a source which may be either coherent or incoherent. An electrical current is applied to the portion of the electrically conducting optical fiber and a magnetic field is applied to the current-carrying optical fiber. A known value of one permits a determination of the presence or absence of the other through electromotive forces on a metallic conductor in a magnetic field, which are used to induce differential phase shifts (coherent optical radiation input) or losses (incoherent optical radiation input) between the fiber modes. These phase shifts or losses are detected by a suitable detector. For a magnetic field of 1 kGauss, good linearity is obtained in the 5 to 2,000 mA current range. Magnetic fields of about 0.1 G to 1 kG are detected employing a current source of about 5 mA to 50 A.

Blazed dielectric gratings with high beam‐coupling efficiencies

Abstract: By using microwave models of optical gratings, we have realized dielectric gratings with asymmetric triangular or trapezoidal profiles that exhibit beam‐coupling efficiencies in excess of 90% over wide ranges of frequencies and grating parameters. These desirable properties are consistent with the behavior predicted by a Bragg scattering analysis of the grating operation, as well as with numerical data provided by an exact solution.

Output light coupling system for semiconductor laser

Abstract: PURPOSE: To efficiently couple the output light of a semiconductor laser and an optical fiber by matching the light distribution of the laser to the light distribution of the optical fiber or the light condensing lens. CONSTITUTION: The Y-axis direction light distribution in the active layer 2 of a semiconductor laser 1 placed on a substrate 8 is expanded by the curvature at the end of a fiber 6a, is matched to the light distribution of the propagation mode of a core 6b, and high efficiency coupling is performed. When suitably selecting the radius R of curvature of the end of the fiber 6a, the light distribution of the Y-axis direction of the laser 1 can be matched to that of the propagation mode of the fiber 6a. COPYRIGHT: (C)1982,JPO&Japio

Strip diode laser with reactance free fiber output

Abstract: A strip diode laser having an optical fiber output free of reactive effects in that an element is inserted between the input of the transmission fiber and output of the laser with the element being one which converts the linearly polarized wave at the laser output to a circularly polarized wave at the transmission fiber input.

Contactless displacement detector employing optical fiber

Abstract: PURPOSE:To manufacture a contactless displacement detector utilizing an optical fiber with a high sensitivity and a wide measuring range by providing an angle between a light projecting optical fiber and a light receiving optical fiber CONSTITUTION:Light from a light source is irradiated on the surface to be measured through a light projecting optical fiber and a light receiving optical fiber arranged in a probe with an angle and the reflected light is taken out to generate electric signals according to the quantity of the reflected light The signals are processed to measure displacement of the surface to be measured For example, light is irradiated on an areas on the surface with a light project- ing fiber 1 at a distance r therefrom and the light from an area S' is received with a light receiving fiber set at a distance d from said fiber with an angle alpha The relationship of a signal output P according to the quantity of the light to the distance r is as shown by the chart with the angle alpha as parameter Thus, a wide range of measurement can be done at a high accuracy

Integrated optical switch

Abstract: PURPOSE:To achieve integration while increasing a branch angle by providing an electrode to each grating formed at the intersection part of an optical waveguide formed in an electrooptic crystal substrate, and by controlling Bragg reflection conditions by applying a voltage. CONSTITUTION:At the intersection parts of optical waveguides 2 formed in an electrooptic crystal substrate 1 of LiNbO3, etc., grating reflectors 6 are provided by ion etching, etc., and an electric field is applied to electrodes 7 and 7' arrnaged at both the sides of each reflector 6 to vary the refractiveity of the grating part. Then, Bragg reflection conditions are changed to perform optical switching. Consequently, integration is achieved with a branch angle increased.

Differential interferometric method for optical fiber testing.

Abstract: A new differential interferometric method of determining the optical characteristics of cylindrical systems is presented. In particular it is applied to the study of a step-index optical fiber where small changes in geometric and optical characteristics have been introduced.