摘要:
A tuneable optical fibre comprising a long-period Bragg grating (5) written in a portion of an optical waveguide (10) comprising a core and an optical cladding (11), characterised in that the portion of the waveguide comprising the grating (5) is at least partially immersed in an external environment consisting of two distinct sections, a first section (1) whose refractive index is higher than that of the optical cladding (11) and a second section (2) whose refractive index is lower than that of the optical cladding (11), the long-period grating being at least partially immersed in one of the said sections so as to almost independently tune the wavelength and/or the contrast of the spectral response of the filter.
摘要:
An optical amplification system is described which comprises an optical amplifier and an optical filter. The gain of the optical amplifier is changeable to different gain values. For every one of the gain values, a wavelength-dependent gain curve exists. At least for one of the gain values, the gain curve varies over the wavelength. An apodized long-period grating (LPG) is used as the optical filter. The apodized LPG provides at least one wavelength-dependent attenuation curve which compensates the gain curve varying over the wavelength.
摘要:
The present invention relates to a Bragg grating filter optical waveguide device, comprising an optical fiber provided with a Bragg grating region which is externally strained to alter the range of chirping. The external strain is induced by a gradient-generating mechanical body bonded onto the length of the fiber grating.
摘要:
An optical chromatic dispersion compensation module consists of a portion of fiber (10) comprising a variable pitch Bragg grating and a mechanical structure (1) consisting of two flexible mountings (2, 2′) and one fixed mounting (3). The portion of fiber (10) is attached to said mechanical structure (1) at three points: A first soft mount point (5) is connected to the fixed mounting (3) and two rigid mount points (4, 4′) are connected to the flexible mountings (2, 2′). The module also consists of a mechanical actuator (20) designed to act on the mechanical structure (1) to compress a first portion of the Bragg grating and to stretch a second portion of the Bragg grating while keeping the central section of the grating fixed. The chromatic dispersion value produced by the Bragg grating filter is thus modified, while its central wavelength remains fixed.
摘要:
An optical chromatic dispersion compensation module consists of a portion of fiber (10) comprising a variable pitch Bragg grating and a mechanical structure (1) consisting of two flexible mountings (2, 2′) and one fixed mounting (3). The portion of fiber (10) is attached to said mechanical structure (1) at three points: A first soft mount point (5) is connected to the fixed mounting (3) and two rigid mount points (4, 4′) are connected to the flexible mountings (2, 2′). The module also consists of a mechanical actuator (20) designed to act on the mechanical structure (1) to compress a first portion of the Bragg grating and to stretch a second portion of the Bragg grating while keeping the central section of the grating fixed. The chromatic dispersion value produced by the Bragg grating filter is thus modified, while its central wavelength remains fixed.
摘要:
A DFB laser (2) is coupled to a monomode line fiber (14) via an isolator constituted by a Faraday rotator crystal (4) and a polarizing fiber (10) which is welded to a fiber to be coupled (14). A focusing lens (8) is integrated in an intermediate block including the rotator crystal (4) and a permanent magnet (6). The invention is particularly suitable for making light-emitting heads for use in optical fiber telecommunications systems.