摘要:
An optical waveguide grating with radiative mode-coupling properties, with exceptional stability and reliability as an optical component, wherein the central wavelength of the rejection band has a low temperature dependence, due to the use of silica glass doped with germanium and boron for the core. The rejection bandwidth can be narrowed without increasing the grating length by forming the radiative mode-coupled optical waveguide grating in an optical waveguide wherein the mean relative refractive index difference of the core is greater than that of optical communication waveguides. The rejection can be increased by reducing the occurrence of cases wherein propagation modes of the core coupled to cladding modes once again couple to the core in palnar optical waveguide gratings formed by making periodic changes in the waveguide structure along the direction of propagation of light in an optical waveguide having a cladding with a lower refractive index than the core surrounding the core, by making the thickness of the cladding at least thirteen times the thickness of the core.
摘要:
A method of producing an optical waveguide grating by exposure to light. An optical waveguide having a core composed of a material wherein the refractive index changes due to exposure to UV light is formed into an optical waveguide grating by applying a grating portion formation step wherein a grating portion is formed by irradiation with UV light at a predetermined spacing, and an overall exposure step after formation of the grating portion wherein the entire grating portion is irradiated with UV light. As a result, the effective refractive index of the grating portion is changed so as to allow the central wavelength to be adjusted without changing the rejection. Consequently, the grating properties can be precisely and easily controlled.
摘要:
An inner cladding exposure section 14 is formed by removing a part of an outer cladding 4 of an optical amplification medium fiber 10 which has a porous layer 3 between the inner cladding 2 and the outer cladding 4 in a longitudinal direction. An end surface 23 of an optical fiber 20 for the excited light incidence is cemented on an outer periphery of the exposed inner cladding 2. The excited light 24 is incident into the optical amplification medium fiber 10 from the optical fiber 20 for the excited light incidence. By doing this, it is possible to provide a method for exciting a light in an optical amplification medium fiber which can realize a superior amplitude while emitting the excited light so as to be incident into the optical amplification medium fiber highly efficiently.
摘要:
Provided is a fiber laser including a mode filter for selectively attenuating, among modes included in laser light propagating through a multi-mode fiber, any mode other than a radially polarized mode. Among the modes included in the laser light propagating through the multi-mode fiber, the fiber laser causes the radially polarized mode to resonate, so as to emit radially polarized laser light. The mode filter includes a long-period fiber grating obtained by writing, to a multi-mode fiber capable of guiding the radially polarized mode, a grating for selectively attenuating any waveguide mode other than the radially polarized mode.
摘要:
The present invention relates to an optical fiber grating manufacturing method comprising the steps of heating intermittently an optical fiber (4) provided with a core (1b) having residual stress in the longitudinal direction; softening a peripheral cladding (1c) of this core (1b); and forming spatial periodic changes for the relative refractive-index difference between said core (1b) and said cladding (1c), in the longitudinal direction of said fiber (4) by having the index of refraction of the core (1b) change through the releasing of said optical fiber. Next, as shown by a broken-line arrow, by the laser scanning device (6d), the laser beam (7) is scanned from the exterior side surface of the optical fiber (4), so as to be scanned traversing the optical fiber (4) in a direction perpendicular to the longitudinal direction of this optical fiber (4). At this time, the optical fiber (4) is heated to a temperature at least equal to or higher than the softening temperature of the cladding (1c).
摘要:
Core comprises a main stem which is formed on a substrate (10), linearly extending in the beam propagating direction and short branches (12a,12b) with a certain length which extend perpendicularly to the beam propagating direction (16) toward both sides along the plane of the substrate and are arranged at regular intervals in the beam propagating direction. Thus, the branches are arranged in a ladder geometry when it is viewed from the top, forming a rectangular waveform arrangement. The core (12) constitutes a grating structure in which the width of the core is made to vary periodically with the branches in the beam propagating direction.
摘要:
An optical waveguide grating with radiative mode-coupling properties, with exceptional stability and reliability as an optical component, wherein the central wavelength of the rejection band has a low temperature dependence, due to the use of silica glass doped with germanium and boron for the core. The rejection bandwidth can be narrowed without increasing the grating length by forming the radiative mode-coupled optical waveguide grating in an optical waveguide wherein the mean relative refractive index difference of the core is greater than that of optical communication waveguides. The rejection can be increased by reducing the occurrence of cases wherein propagation modes of the core coupled to cladding modes once again couple to the core in palnar optical waveguide gratings formed by making periodic changes in the waveguide structure along the direction of propagation of light in an optical waveguide having a cladding with a lower refractive index than the core surrounding the core, by making the thickness of the cladding at least thirteen times the thickness of the core.