TW386165B - Compensation method for fine-tunable fiber raster and apparatus therefor - Google Patents

Abstract

The compensation method and apparatus for fine-tunable fiber raster. A fiber having a raster is connected on a dual-metal structure which is then clamped with a fixture device to make this dual-metal structure a cantilever beam to compensate for the variation of inter-grid width of the raster. Moreover, a spacer can be inserted between dual-metal structure and fixture device such that a deflection occurs in the dual-metal structure for compensation of the variation of inter-grid width of the raster.

Description

V. Description of the invention (1) The present invention relates to a fine-tunable fiber grating compensation method and device. -Fiber Bragg Grating (FBG) is widely used in manufacturing various components of high-density divided wavelength multiplexer (WDM) network, such as FBG stable laser light source, and used in multiplexer, demultiplexer and increase / decrease Various WDM devices in add / drop filters. However, in actual use, the rise in ambient temperature will have an impact on the fiber grating: Because the width of the grating between the fiber gratings will determine the center frequency of the reflected light, it must be very accurate in design and manufacturing. When it rises, the thermal expansion-contraction-contraction effect of the optical fiber drawing will be extended, which will make the grating width of the fiber grating larger and deviate from the design value. This kind of phenomenon must be thought of to prevent it. Figure 1A shows a conventional fiber Bragg grating temperature compensation device using a bimetal structure, which is composed of two arms 13, 13 and two metal plates 4, 15, wherein the metal plates 14, 15 are welded together, and the arms 13, 13, welded on both sides of the metal plate. The thermal expansion coefficient of the metal plate 1 4 is smaller than that of the metal plate 5. In use, an optical fiber 11 provided with a grating 12 is attached to the arms 13 and 13 '. If the ambient temperature increases, the optical fiber 1 tends to expand due to thermal expansion. However, at this time, the temperature compensation device is thermally expanded due to the metal plates 14, 15 The coefficient is not equal to that of Baoqu (as shown in Figure 1B), which can prevent the fiber " elongation. The use of k methods can greatly reduce the width of the grating compensation grid caused by the temperature rise. The above-mentioned temperature compensation device can be broken. It can reduce the impact of temperature changes on the light peach.1 Because of the tolerances caused by the manufacturing and packaging process, it will make The compensation in this way cannot be very accurate ($ refers to the package, {the temperature compensation

i. Description of the invention (2) The device is placed in a box, and the two ends of the optical fiber are fixed on the box, which can prevent the temperature compensation device from being damaged when an unintentional external force acts on the fiber). For example, when (1) the optical fiber is adhered to the bimetal structure; (2) the two ends of the optical fiber are fixed to the box during packaging, the width of the optical fiber can be caused, and the error "although the design will actually produce a certain tolerance Shadow is very accurate. The purpose of the present invention is to solve the compensation method and device for a fiber Bragg grating. An optical fiber with a thumb is formed, and then the bimetal structure can be changed to a cantilever structure. In addition, 'a gap sheet can be used' to flex the bimetal structure. Too tight and inadvertently increasing the grating grid usually does not compensate for the tolerance, but it does not allow the above temperature compensation to provide the above problem and provides a fine-tuning method according to the present invention. A bimetal structure is connected with a fixing device to clamp the bimetal junction. In order to compensate the grid width of the grating in the bimetal structure and the fixing device to compensate the grid width of the grating, the above-mentioned features, features, and advantages of the present invention can be more clearly and easily illustrated. Simple description: Schematic (detailed description. Device; Figure 1A shows the conventional fiber grating temperature compensation using a bimetal structure

V Fig. 1B shows the bending of the fiber grating in Fig. 1 when the temperature rises; Fig. 2A is a three-dimensional exploded view of an embodiment of the fine-tunable fiber optic peach according to the present invention; -2D image shows the fine-tunable fiber grating compensation device of Fig. 29

The fifth page is the combination steps of the description of the invention (3). Figure 3 shows the fine-adjustable fiber grating compensation device shown in Figure 2A when the temperature rises. Figure 4 is based on 3 @ 丨The geometric analysis is not intended. Fig. 5 shows the relationship between the vertex of the arm in the present invention: the horizontal displacement X of the point and the length of the cantilever beam L. Fig. 6 is a plan view of the fixing member of the fine-adjustable fiber grating compensation device of the present invention. Figure 7 shows another embodiment of the fine-tuning-adjustable fiber grating compensation device 9 of the present invention. Figure 8 shows the relationship between the vertex of the arm in the present invention: the horizontal displacement X of the point and the thickness h of the gap sheet. 12 Grating 13 Arm 13 'Arm 14 Metal plate 15 Metal plate 22 Bimetal structure 23 Upper fixing member 24 Lower fixing member 25 Upper cover 26 Base 27 Side cover 30 Gap piece 221 Metal plate 222 Metal plate 223 Arm. 223' Arm 231 Depression 261 The holes 262 grooves are described in conjunction with the drawings to illustrate a preferred embodiment of the present invention. (

C

5. Description of the invention (4) Please refer to FIG. 2A. The fine-adjustable fiber grating compensation device of the present invention includes a bimetal structure 22, an upper fixing member 23, and a lower fixing member 24. The bimetal structure 22 is composed of two arms 223, 223 'and two metal plates 221, 222', wherein the thermal expansion coefficient of the metal plate 221 is smaller than that of the metal plate 222, and the two metal plates 221, 222 are welded together, and the arms 223, 223, which are respectively welded to two ends of the metal plates 221 and 222. An optical fiber 11 provided with a grating 12 is adhered to the arms 223, 223 '. < The above two fixing members 23 and 24 are I-shaped for clamping the bimetal structure 22, and a recess is provided at the bottom of the upper fixing member 23, 231, for receiving the metal plate 221 during clamping , 222 (as shown in FIG. 2B), and then fasten the two fixing members 23, 24 with screws. Next, the fine-adjustable fiber grating compensation device of the present invention is packaged with an upper cover 25, a base 26, and a side cover 27. The base 26 has a hole 261 and two grooves 262. A fine-adjustable fiber grating compensation device is placed in the hole 261, and the optical fiber 11 is housed in the groove 262 (as shown in FIG. 2C). It is fixed to prevent the compensation device from being damaged when an unintentional external force acts on the optical fiber. Finally, the upper cover 25 and the side cover 27 are locked on the base 26 to complete the package (as shown in FIG. 2D). It will now be explained how the present invention solves the problems caused by temperature changes. When the ambient temperature rises', the bimetal structure 22 is bent due to the different thermal expansion coefficients of the two metal plates 221 and 222 (as shown in Fig. 3). The feature of the present invention is that the horizontal displacements of the arms 13, 13 'are controlled by holding the metal plates 221, 222 by the fixing members 23, 24. inmi mi page 7 V. Description of the invention (5) Due to the clamping of the upper and lower fixing members 23, 24, the bimetal structure 22 behaves like a cantilever beam. The effect of temperature changes on the cantilever beam bending is as follows: (l) 2 Tt -7; 3 (1 + w) 2 + (1 + + where

Rt is the radius of curvature of the metal plate at temperature Tt; R. For metal plates at temperature T. Radius of curvature at time; n ^ SyS2, where Lu is the thickness of the metal plate 221, and \ is the thickness of the metal plate 222; 11 = 1 / Ez, where £ 1 is the elastic modulus of the metal plate 2 21, and e2 is The elastic modulus of the metal plate 222; A is the thermal expansion coefficient of the metal plate 221; α2 is the thermal expansion coefficient of the metal plate 221; S = S] + S2 if the metal plate is at temperature T. Time is flat, then Rq = 〇〇 and 1 / R / 0. Assume that the two metal plates 221 and 222 have the same thickness, that is, Si = S2 = S / 2. Please refer to Figure 4, which can be obtained from a right-angled triangle EFG: (^ + |) 3 = (^ +-^ 4) 2 + £ 2 (2) ^ 2 where A is the deflection of the cantilever beam (deflection); L is Cantilever length》

Page 8 (4) (3)

(4) (3) V. Description of the invention (6) Equation (2) can be rewritten as 1__2A

L ^ + A ^ -AS If you subtract Equation (1) from Equation (3), you get 2A _ 6 (^ 3-0 ^) (1 + ^) 3 Ά £ + j4 淑 3 (l + w ) 2+ (l + «i«) (w3 + __ L) In Figure 4, 'label a is the deflection angle of the cantilever beam, label L' is the length of the arm 223 or 223 ', and label X is the arm 223 or 223 , The horizontal displacement of the vertex 'hence ·

Since tan a = A / L x ^ L ', A ...... (5), ^ ΰλ-Α7 In the formula (4),' Α, α2, m, n, Tt, T. And s is a known number, so the deflection A of the cantilever beam can be determined by L; and in equation (5), L is a known number, so the horizontal displacement of the vertex of the arm 223 or 223 'is determined, so according to Types ⑷ and ⑸, the horizontal displacement χ can be completed depending on the decision. Figure 5 shows the relationship between X and l according to equations (4) and (5), where m = l 'n = 1.287, L, = 6.5 (nim), Tt-T0 = 55 (t :): α = 8 4

Xl0-6 (l / ° C) e '2i Please refer to FIG. 6. In actual operation of the present invention, the fixing members 23 and 24 of various widths W are prepared in advance, and the fixing members 23 and 24 of different width boundaries are prepared in advance. 24 will produce different cantilever beam lengths L, so for different environmental temperature changes, the present invention can flexibly select and replace the appropriate width W to

Page 9 V. Description of the invention (7) This is used to accurately compensate for the proper cantilever beam length L caused by the temperature rise, resulting in a change in the fiber length. As shown in Fig. 6, since the fixing members 23 and 24 of various widths W are prepared in advance, the fixing members of appropriate widths can be immediately selected and replaced as needed, which is very convenient to use. The compensation device of the fine-adjustable fiber grating of the present invention can also be used to compensate the error between the widths of the gratings produced during manufacturing and packaging. Referring to FIG. 7 ', a gap piece 30 is inserted between the lower fixing member 24 and the metal plate 30 to deflect the cantilever beam. The lower fixing member 24 has an L " wider than the upper fixing member 23. Assuming that the deflection angle a of the cantilever beam is very small, then: In equation (6), L 'and L " are known numbers, so the horizontal displacement X of the vertex of the arm 223 or 223 can be determined by h. Figure 8 shows the relationship of x & h, where L '= 6.5 (mffl) and L " = l (inm). Therefore, inserting the thick-production gap sheet 30 according to the formula (6) can cause an appropriate horizontal displacement χ to compensate for the error in the width between the grating grids during the manufacturing process. Although the present invention has been disclosed in the preferred embodiment as above, it does not limit the present invention. Any person skilled in this art can still make some changes and retouches without departing from the scope and spirit of this publication. ^ The scope of protection shall be determined by the scope of the attached patent application. Guarantee

Claims (1)

88104549 Six 'application for patent scope 1. A fine-tunable fiber grating compensation method, including: (a) preparing a bimetal structure' reading a bimetal structure far away to knot a fiber with a grating; (b) making the bimetal A predetermined part of the structure is flexible. 2. A fine-tunable compensation method for fiber gratings, including: (a) preparing a bimetal structure, and connecting a bimetal structure with a grating fiber; 1-1 (b) flexing the bimetal structure Qu a given angle. 3. A compensating device capable of micro-chirping an optical weave grating, comprising: a bimetal structure 'connecting an optical fiber to the bimetal structure; and a fixing device of 胥 it peach, which holds the bimetal structure so that the Double gold is cantilevered to compensate for the change in the grid width of the grating. The center and the center 4 are as follows: the compensation device of the fine-adjustable fiber grating described in item 3 of the patent scope, wherein the fixing device includes a second fixing member of a first fixing grid, and the first,-, c thousand From the first bimetal structure. -The fixing member holds the compensation device of the fine-tunable fiber grating as described in item 4 of the patent scope from two opposite directions, and wherein the complementary bimetal structure of the first fixing grating. The compensation device for fine-tuning fiber gratings as described in item 4 of the scope of the patent application is used by the company. The compensation device further includes a k-structure: two fixed members, and S1 film is used to drop the film. , Inserted between the bimetal structure and the second fixing member to change the bimetal structure.