KR20020019684A - Fabrication device of overlapped long period optical fiber grating - Google Patents

Abstract

PURPOSE: An apparatus for fabricating an overlapped long period fiber grating is provided to form an overlapped long period fiber grating without connecting optical fiber gratings having different periods to each other. CONSTITUTION: A plurality of beam splitters(110,122) are used for separating a laser beam having a predetermined ratio from output beams of a laser beam source and passing the remaining beam except for the separated laser beam having the predetermined ratio. A plurality of mirrors(120) are used for reflecting the beam separated from the beam splitter(110,122). The first amplitude mask(116) has a predetermined period. The first amplitude mask(116) is used for exposing the first region of an optical fiber by passing selectively the leaser beam passing the beam splitter(110). The second amplitude mask(128) has a period different from the period of the first amplitude mask(116). The second amplitude mask(128) is used for exposing the second region of the optical fiber by passing selectively the laser beam reflected by the mirrors(120).

Description

Overlapping Long Cycle Fiber Grating Manufacturing Equipment {FABRICATION DEVICE OF OVERLAPPED LONG PERIOD OPTICAL FIBER GRATING}

The present invention relates to an optical fiber, and more particularly to an apparatus for manufacturing a long period optical fiber grating.

The long period optical fiber grating, which is one of the optical components constituting the optical transmission system, couples an optical signal of a specific wavelength band in the cladding mode and passes an optical signal of the remaining wavelength band in the optical fiber. The long period fiber grating is utilized as an optical filter and an optical sensor such as a nonreflecting band-rejection filter and a bandpass filter, and in particular, an overlapping long period fiber grating Fiber grating is used as a gain flatten filter.

The manufacturing method of the long period optical fiber grating is found by K.O. Hill et al. Published in 1978 by APPL. PHYS. Lett., Vol. 32, "Germanium-doped optical fiber," as disclosed in "Photosensitivity in optical fiber waveguides: Application to reflection filter fabrication" pp. 647-649, is sensitive to UV light. ") Is based on the principle."

In addition, a representative method for manufacturing the long period optical fiber grating is developed by G. Meltz et al., Published in Opt. Lett., Vol. 14, "Formation of Bragg gratings in optical fibers by a tranverse holographic method" pp.823 to 825, the ultraviolet irradiation method by "side writing" is mainly applied.

On the other hand, the manufacturing method of the long period optical fiber grating by ultraviolet irradiation can be described through the following equation (1) and (2).

(Wherein β _co is the propagation constant of core mode, β _cl ⁽ⁿ⁾ is the transfer constant of n-th order cladding mode, Λ is the grating period)

By substituting β = 2πn / λ into Equation 1, Equation 2 below can be obtained.

Where n _co is the refractive index of the core, n _cl is the refractive index of the clad, and λ is the coupling wavelength.

As can be seen in Equation 2, in order to shift the wavelength coupled from the core mode to the cladding mode, the grating period Λ and the refractive index difference n _co − n _cl must be adjusted.

On the other hand, Figure 1 is a schematic diagram showing a superimposed long-period fiber grating according to the embodiment of the prior art. As shown in FIG. 1, the superimposed long-period optical fiber grating 10 according to the embodiment of the prior art separately forms the long-period optical fiber gratings f1, f2, and f3 having different periods Λ1, Λ2, Λ3. Then, it produced by connecting the edge part and the edge part of each long period optical fiber grating f1, f2, f3.

However, when using the above method, in order to connect each long-period fiber grating, a separate splicing means such as a fusion splicer is required as well as a long time for the splicing process. In addition, since the connection portion of the long-period optical fiber grating is easy to be damaged by an external impact, reinforcing means such as a shrinking tube is required to reinforce it, and there is a problem that a connection loss occurs due to artificial connection of the long-period optical fiber grating.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide an overlapping long period optical fiber grating manufacturing apparatus capable of manufacturing an overlapping long period optical fiber grating without interconnecting long period optical fiber gratings having different periods.

Another object of the present invention is to provide a superimposed long-period fiber grating manufacturing apparatus that does not require a separate connecting means or reinforcing means.

In order to achieve the above object, the present invention provides a device for forming a grating in the optical fiber, the laser light source; A beam splitter for separating a laser beam having a predetermined ratio among the laser beams output from the laser light source and passing the remaining laser beams; A mirror reflecting the laser beam separated from the beam splitter; A first amplitude mask for selectively passing a laser beam passing through the beam splitter to expose the first region of the optical fiber; And a second amplitude mask having a different period from the first amplitude mask and selectively passing a laser beam reflected by the mirror to be exposed to a second region of the optical fiber. to provide.

The present invention also provides a device for forming a grating on an optical fiber, comprising: a laser light source; A first beam splitter which separates a laser beam of a predetermined ratio from the laser beams output from the laser light source and passes the remaining laser beams; A first mirror reflecting the laser beam separated from the first beam splitter; A first amplitude mask selectively passing through the laser beam passing through the first beam splitter to expose the first beam of the optical fiber; A second beam splitter for separating a predetermined ratio of the laser beams reflected from the first mirror and passing the remaining laser beams; A second amplitude mask having a period different from that of the first amplitude mask and selectively passing a laser beam passing through the second beam splitter to be exposed to a second region of the optical fiber; A second mirror reflecting the laser beam passing through the second beam splitter; A third mirror reflecting the laser beam reflected by the second mirror; And a third amplitude mask having a period different from that of the first and second amplitude masks and selectively passing through the laser beam reflected by the third mirror to expose the third region of the optical fiber. Provides long-term optical fiber grating manufacturing apparatus.

1 is a schematic diagram illustrating a superimposed long period optical fiber grating according to an embodiment of the prior art,

2 is a block diagram showing a superimposed long-period optical fiber grating manufacturing apparatus according to a preferred embodiment of the present invention,

3 is a perspective view showing a superimposed long-period fiber grating according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: laser light source 110: first beam splitter

112: first light attenuator 114: first beam shutter

116: first amplitude mask 120, 130, 132: mirror

122: second beam splitter 124: second optical attenuator

126: second beam shutter 128: second amplitude mask

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

2 is a block diagram showing a superimposed long-period fiber grating manufacturing apparatus according to a preferred embodiment of the present invention, Figure 3 is a perspective view showing a superimposed long-period fiber grating according to a preferred embodiment of the present invention. 2 and 3 show an apparatus for manufacturing a long period optical fiber grating having three different periods, but a long period optical fiber having three or more different periods through the addition of a beam splitter, a mirror, an optical attenuator and an amplitude mask. Lattice can be produced.

As shown in FIGS. 2 and 3, the overlapping long-period optical fiber grating manufacturing apparatus according to the preferred embodiment of the present invention uses one laser light source 100 and a laser beam output from the laser light source 100 in the optical fiber longitudinal direction. It consists of three groups for exposure to three different areas of. As the laser light source 100, an ultraviolet laser light source such as an excimer laser is used.

First, the first group for exposing the laser beam to the first region of the optical fiber, the first beam splitter for separating a predetermined proportion of the laser beam of the laser beam output from the laser light source 100 and passing the remaining laser beam ( 110, a first optical attenuator 112 for adjusting the intensity of the laser beam passing through the first beam splitter 110, and outputting the laser beam output from the first optical attenuator 112. A first amplitude mask 116 having a first beam shutter 114 and a predetermined period Λ1 and selectively passing a laser beam passing through the first beam shutter 114 to be exposed to the first region of the optical fiber f; It is composed of

The second group for exposing the laser beam to the second region of the optical fiber includes a mirror 120 reflecting the laser beam separated from the first beam splitter 110 and a laser beam reflected by the mirror 120. The second beam splitter 122 which separates a laser beam of a predetermined ratio among the beams and passes the remaining laser beams, and a second light attenuator 124 that adjusts and outputs the intensity of the laser beam passing through the second beam splitter 122. ), The second beam shutter 126 for adjusting the exposure time of the laser beam output from the second light attenuator 124 and the second beam shutter having a period Λ 2 different from that of the first amplitude mask 116. And a second amplitude mask 128 that selectively passes the laser beam passed through 126 to be exposed to the second region of the optical fiber f.

The third group for exposing the laser beam to the third region of the optical fiber includes two mirrors 130 and 132 reflecting the laser beam separated by the second beam splitter 122 and the mirror 132. A third light attenuator 134 for adjusting and outputting the intensity of the laser beam reflected on the third beam shutter, a third beam shutter 136 for adjusting the exposure time of the laser beam output from the third light attenuator 134, and the first light attenuator A laser beam passing through the third beam shutter 136 having a period Λ3 different from that of the amplitude mask 116 and the second amplitude mask 128 and selectively passing through is exposed to the third region of the optical fiber f. And a third amplitude mask 138.

In the superimposed long-period optical fiber grating manufacturing apparatus according to the embodiment of the present invention, the laser beam output from one laser light source 100 is divided using the beam splitters 110 and 122 and the mirrors 120, 130 and 132, The divided laser beam is passed through amplitude masks 116, 128, 138 having different periods Λ1, Λ2, Λ3, respectively, to be exposed to different regions of the optical fiber f, thereby simultaneously extending the length of the optical fiber f. Three regions with different periods over each other are formed to overlap.

In this case, the light attenuators 112, 124, 134 of each group adjust the intensity of each divided laser beam, and the beam shutters 114, 126, 136 of each group have a laser beam in the optical fiber f. It is used to control the time it is exposed.

On the other hand, according to an application of the present invention, one side of the optical fiber f is applied by rotating or twisting the optical fiber f at a constant speed while exposing the laser beam to the optical fiber f to form a long period optical fiber grating. It is possible to reduce the refractive index asymmetry in the optical fiber (f) generated by the irradiation of the laser beam only to the side.

As described above, the superimposed long-period fiber grating manufacturing apparatus according to the embodiment of the present invention may improve the operating characteristics of the superimposed long-period fiber grating due to no optical fiber connection loss.

In addition, the overlapped long period optical fiber grating manufacturing apparatus according to the embodiment of the present invention does not need to use the optical fiber connecting means or reinforcing means, there is an effect that can increase the productivity of the overlapped long period optical fiber grating.

Claims (6)

An apparatus for forming a grating on an optical fiber, A laser light source; A beam splitter for separating a laser beam having a predetermined ratio among the laser beams output from the laser light source and passing the remaining laser beams; A mirror reflecting the laser beam separated from the beam splitter; A first amplitude mask for selectively passing a laser beam passing through the beam splitter to expose the first region of the optical fiber; And a second amplitude mask having a different period from the first amplitude mask and selectively passing a laser beam reflected by the mirror to expose the second region of the optical fiber. The method of claim 1, And a beam shutter for adjusting the exposure time of the laser beam passing through the beam splitter and the laser beam reflected by the mirror, respectively. The method of claim 1, And an optical attenuator for adjusting the intensity of the laser beam passing through the beam splitter and the laser beam reflected by the mirror, respectively. An apparatus for forming a grating on an optical fiber, A laser light source; A first beam splitter which separates a laser beam of a predetermined ratio from the laser beams output from the laser light source and passes the remaining laser beams; A first mirror reflecting the laser beam separated from the first beam splitter; A first amplitude mask selectively passing through the laser beam passing through the first beam splitter to expose the first beam of the optical fiber; A second beam splitter for separating a predetermined ratio of the laser beams reflected from the first mirror and passing the remaining laser beams; A second amplitude mask having a period different from that of the first amplitude mask and selectively passing a laser beam passing through the second beam splitter to be exposed to a second region of the optical fiber; A second mirror reflecting the laser beam passing through the second beam splitter; A third mirror reflecting the laser beam reflected by the second mirror; And a third amplitude mask having a period different from that of the first and second amplitude masks and selectively passing through the laser beam reflected by the third mirror to expose the third region of the optical fiber. Long cycle optical fiber grating manufacturing device. The method of claim 4, wherein And a beam shutter for adjusting the exposure time of the laser beam passing through the first beam splitter, the laser beam separated from the second beam splitter, and the laser beam reflected on the third mirror. Nested Long Cycle Fiber Optic Grid Manufacturing Device. The method of claim 4, wherein And an optical attenuator for adjusting the intensity of the laser beam passing through the first beam splitter, the laser beam separated from the second beam splitter, and the laser beam reflected from the third mirror. Long cycle fiber optic grating manufacturing device.