Optical waveguides – With optical coupler – Input/output coupler
Reexamination Certificate
1999-10-13
2001-08-14
Healy, Brian (Department: 2874)
Optical waveguides
With optical coupler
Input/output coupler
C385S031000, C385S033000, C385S123000, C430S056000, C430S290000, C065S385000, C065S485000
Reexamination Certificate
active
06275631
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled APPARATUS FOR FABRICATING LONG-PERIOD GRATING FILTER earlier filed in the Korean Industrial Property Office on the 13
th
day of October 1999, and there duly assigned Ser. No. 42712/1998, a copy of which is annexed hereto.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to an apparatus for manufacturing a long-period optical fiber grating.
2. Related Art
An optical fiber communication system consists of an information source, a transmitter or modulator, a transmission medium, and a receiver or demodulator at a destination point. The information source provides an electrical signal to the transmitter. The transmitter comprises an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversion may be a semiconductor laser. The transmission medium consists of an optical fiber cable. The receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation of the optical carrier. Thus there is a requirement for electrical interfacing at either end of the optical link. Fiber optic communications offer major advantages over wire systems because of low attenuation and high bandwidth available.
An optical fiber cable is an optical fiber waveguide having a core of a first refractive index n
1
surrounded by a transparent cladding of slightly lower refractive index n
2
. The cladding supports the waveguide structure while also substantially reducing radiation loss into surrounding air. The optical fiber cable corresponds to a single cylindrical glass fiber having a diameter comparable to the diameter of a human hair. The optical fiber cable acts as an open optical waveguide. Light which is launched into an optical fiber at an angle less than an acceptance angle demonstrate total internal reflection in the core of the optical fiber. Periodic structures maybe incorporated into planar waveguides to form integrated optical filters. An optical filter can be used to guide light to the core of an optical fiber causing the light to propagate in the core of that optical fiber.
One type of optical filter is a long period grating filter. I have found that there is a need for an improved apparatus for manufacturing long-period optical fiber grating. Efforts have been made to improve optical fiber-related components.
Exemplars of recent efforts in the art include U.S. Pat. No. 5,596,442 for BRAGG REFLECTION GRATINGS IN OPTICAL FIBERS issued to Byron, U.S. Pat. No. 5,951,881 for FABRICATION OF SMALL-SCALE CYLINDRICAL ARTICLES issued to Rogers, et al., U.S. Pat. No. 5,912,999 for method for FABRICATION OF IN-LINE OPTICAL WAVEGUIDE INDEX GRATING OF ANY LENGTH issued to Brennan, III, et al., U.S. Pat. No. 5,898,804 for OPTICAL FIBER HAVING CORE SEGMENT WITH REFRACTIVE-INDEX GRATING issued to Wickham, U.S. Pat. No. 5,881,188 for OPTICAL FIBER HAVING CORE SEGMENT WITH REFRACTIVE-INDEX GRATING issued to Starodubov, U.S. Pat. No. 5,787,213 for METHOD AND APPARATUS FOR WRITING BRAGG GRATINGS ON STRAINED OPTICAL FIBERS issued to Brownlow, and U.S. Pat. No. 5,620,496 for METHOD OF MAKING STABLE OPTICAL DEVICES EMPLOYING RADIATION-INDUCED INDEX CHANGES issued to Erdogan, et al.
While these recent efforts provide advantages, I note that they fail to adequately provide an improved apparatus for efficiently and conveniently manufacturing long-period optical fiber grating.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide an apparatus for fabricating along-period fiber grating, by which the period of a long-period fiber grating is controlled by adjusting the size of a laser beam by including a dispersing portion for dispersing incident light, a cylindrical lens for collimating dispersed light, and a composite amplitude mask having a controllable period.
Another objective is to provide an improved apparatus for efficiently and conveniently manufacturing long-period optical fiber grating. Accordingly, to achieve the above objectives and others, the present invention provides an apparatus for manufacturing a long-period fiber grating, the apparatus including: a laser source; a first lens for adjusting the focal point of laser generated by the laser source; a dispersing portion for dispersing laser passed through the first lens so that the size of a beam of the laser is broadened; a second lens for collimating the dispersed laser; and a composite amplitude mask for periodically transmitting laser collimated by the second lens, to an optical fiber, wherein the refractive index of the core of the optical fiber is periodically changed by laser which has passed through the composite amplitude mask.
To achieve the above objectives and others, the present invention also provides an apparatus for manufacturing a long-period fiber grating, including: a laser source; a first lens for adjusting the focal point of laser generated by the laser source; a dispersing portion for dispersing laser passed through the first lens so that the size of a beam of the laser is broadened; a second lens for collimating the dispersed laser; a composite amplitude mask for transmitting laser collimated by the second lens, to an optical fiber in the period of a transmission area; a measuring unit for measuring the coupling peak of a long-period fiber grating formed on the optical fiber by laser which has passed through the composite amplitude mask; and a control unit for controlling the rotation angle of the composite amplitude mask so that a measured coupling peak occurs at a desired wavelength, wherein the period of the transmission area of the composite amplitude mask is determined by rotating two amplitude masks, each formed by alternating transmission areas for transmitting the laser with non-transmission areas through which the laser is not passed, by a predetermined angle in opposite directions.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an apparatus for manufacturing a long-period fiber grating, comprising: a laser unit emitting laser light; a first lens adjusting the focal point of the laser light generated by said laser unit; a dispersing portion dispersing the laser light passed through said first lens and broadening a beam of the laser light; a second lens collimating the dispersed laser light; and a composite amplitude mask periodically transmitting to an optical fiber the laser light collimated by said second lens, the optical fiber having a refractive index of a core of the optical fiber periodically changed by the laser light which has passed through said composite amplitude mask.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an apparatus for manufacturing a long-period fiber grating, comprising: a laser source outputting laser light; a first lens adjusting a focal point of the laser light output by said laser source; a dispersing unit dispersing the laser light passed through said first lens and broadening a beam of the laser light; a second lens collimating the dispersed laser light; a composite amplitude mask having a transmission area transmitting the laser light collimated by said second lens, said composite amplitude mask transmitting the laser light to an optical fiber in a period of said transmission area; a measuring unit measuring a coupling peak of said long-period fiber grating formed on the optical fiber by the laser light transmitted through said composite amplitude mask; and a control unit controlling a rotation angle of said composite amplitude mask to cause said measured coupling peak to occur at a desired wavelength.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and br
Bushnell , Esq. Robert E.
Healy Brian
Samsung Electronics Co,. Ltd.
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