JPS5872911A - Optical fiber connecting method - Google Patents

Abstract

PURPOSE:To connect optical fibers with a small loss, by immersing the end part of one optical fiber in a liquid, which etches a dopant containing quartz glass faster than a quartz glass, and immersing the end part of the other optical fiber in a liquid, which etches the dopant containing quartz glass slower than the quartz glass, and butting both end faces. CONSTITUTION:An optical fiber where an SiO2 containing a GeO2 is used for a core 12 and an SiO2 which does not contain a dopant is used for a clad 11 is immersed in an HF liquid and is etched to obtain an end face 14 where the core 12 is recessed. Meanwhile, a liquid where the HF liquid is added to NH4F is used as the etching liquid to an end face 13 where the core 12 projects. Both optical fiber end faces 13 and 14 are butted. Thus, it is unnecessary to connect them while monitoring the intensity of light, and optical fibers are connected with a small loss.

Description

[Detailed description of the invention] The original F! # relates to a method of connecting nine fibers by forming a concavo-convex tube for joining j1mK by utilizing the difference in etching of the optical 7-eyeper j111 pattern and positioning the joint at the time of joining.

Conventionally, the connection method of the optical 7-iper was configured as shown in Figure 1.
The ends of b break directly on the fiber axis, respectively.
V# with 7 Eyepa 1a*1b linked with fine movement table respectively.
The end faces of the eyepieces 7 and 7 are aligned so that they face each other while being fixed in the position Z and visually inspected using a mold mirror 6. At this time, if the core diameter is as small as 5 to lQ71gl1m like a single mode optical fiber, the alignment fi1m! Conventional mechanical alignment uses visual inspection sound, making it difficult to achieve low-loss connections.As a solution to this problem, the end of one source fiber l& JI of light source 4 from part
tt incident, the other source fiber 1bK is transmitted through the connection point, and a photodetector 5 is placed on the other party fiber xbv*111 to detect the transmission level at the connection point. A method is used to compensate for alignment accuracy at I-continuation points.

In this way, in addition to visual connection, conventional connection methods
Since an inspection mechanism based on the transmission of detection light is required, the configuration is extremely complicated and the connection procedure is also complicated.

In the present invention, by adding an etching process to the original fiber surface, a concave portion is formed in the direction of one end of the optical fiber, and a convex portion is formed in the direction of the other original fiber. As a result of this research, we provide a method 1 that eliminates the complicated procedure of connecting optical 7-IPA while transmitting and monitoring the 9-inspection light, and allows connection of original 7-IPA with low loss. In order to achieve the above object, the present invention has the following structure [i.e., original fibers made of quartz glass and dopant-containing quartz glass are connected to each other, Using a first etching solution that etches quickly and a second etching solution that etches the dopant-containing quartz glass more slowly than the silica glass, one end of the optical fiber is immersed in the tm-etching solution, and the other end is immersed in the tm-etching solution. End *1 After soaking in the second etching solution, bring together the 7 sides of both sides and join them.
Make it moldy.

The present invention will be described in detail below with reference to #Cm[I. Diagram 2-) 伽) ←) Indicating the trend of the optical fiber according to the mineral water invention, 11 is a cladding portion made of quartz glass, 12 is a core, and ls is a core portion formed in a convex shape and facing towards the end, 14 is a jilli whose core is formed in a concave shape, 1
5tijt7 Aibarai Shows the joint surfaces when they are butted against each other. Hikari 7 Aiba no Otori 11 #17 Aipa Center 1i (Core)
There is a method in which a cladding with a low refractive index is provided around the outer periphery of the cladding, and jt, t-transmission is carried out using the internal reflection. ζ Trowel quartz glass (silica) #i Glass-like pure 810m diameter]
It is also a low-loss material in the light wave or near-infrared regions. The material itself has a refractive index of about 145 (To), which is among the lowest among optical glasses. For this reason, in silica-based optical fibers, silica glass (core) is made of high-quality silica glass, either by using a low refractive index material in the cladding or by adding P (synthetic) (germanium) to the core. A method of changing the refractive index is used. Therefore, the etching speed of pure silica glass and silica glass containing these dopants [
K difference occurs. Incidentally, if the etching rate of silica glass containing various dopants is kept constant using [1] iF49 m-etching at, the following results are obtained. First, the etching rate of quartz glass at 49% If is approximately 2301/B.
θC deme9, again Qe O! Etched series of quartz glass flooded with lO% roe is about 1100%/&C.
Further, the etching rate of nine quartz glass added with 0.2 molt of G41 is about 3201/-.C. In this way, HFi
! 'ii When etching an optical fiber SSt as an etching solution, the etching speed differs depending on the presence or absence of a dopant. Therefore, Bi(
Blot using hi and no dopant in the cladding
When etching is performed using the original fiber 11ny solution used in F, the amount of etching of the core is greater than the amount of etching of the cladding, resulting in a concave end face of the core. On the other hand, as an etching solution, NHa1! (401i water #
Using H1 wave @49vol-additional to liquid 1), the relative refractive index difference between the core and cladding is 0431! When etching on a single mode fiber with (GeOl doping amount 4.3 mol S), the ratio of the cladding etching rate to the core etching rate is I! It changes as shown in FIG. 4 depending on the amount of 1 added. That is, Nu,y(40-) :]1I
When IF(49-)"e: 1, the etching speed f of the cladding (silica glass) reaches approximately 1.3 times the etching speed f of the core (G.08 doped silica glass), which is 1ILrc. Therefore, if the etching process is carried out under the conditions in the range 1-1 for the cladding etching rate and the core etching sequence tn, a multi-convex end face will be obtained as shown in Figure 2-), and It can be seen that when etching is carried out under the conditions of 112 wJ (b), the core becomes concave. The original fiber directions are faced and fixed at v# ■ constant A21.An enlarged view of the fixed optical fiber end is shown in Fig. 5(a)K.This end S
While monitoring with a T-blending mirror, it is aligned by a VST-driven fine movement mechanism, and the unevenness on both end faces are fitted and the core is positioned in the center.◎The bale, the discharge electrode 22
Producing a shear arc discharge, the original fiber 20&#
20b is fusion spliced.

In order to actually perform & based on the above method, HF
Or after etching with NH4F + HP solution,
If you leave it in that state, the remaining etching solution will
7. The fibers are further eroded and the fibers are strengthened (1) after soaking in this etching solution, washed with alcohol, then neutralized with boric acid). In addition, it is necessary to clean the etching with pure water.To perform this etching safely, use a structure with a liquid reservoir on the top of the container as shown in the figure. etching liquid,
It is recommended to store and use alcohol, boric acid, and pure water.◎ Also, as another example of T-connecting optical fibers with uneven end faces, you may use the VS connector shown in Figure 7. . In other words, ① The connecting device is connected to the base body 40 formed with a V connecting tube, and the original fiber is inserted from both sides along this V #. 42, # axis alignment is coming. Next, constant sliding with the holding plate 41 results in a low-loss connection ◎Furthermore, when using a connector, not only the above-mentioned V-shaped connector but also other connectors can be used to achieve the Arashi V%o, that is,
As shown in Figure 8, the hole t is slightly thicker than the outer diameter of the 7-eyeper.
- A pair of optical fibers with a concave and convex core formed using a capillary with 50 holes [If inserted from both ends of the capillary and butted against each other, alignment can be achieved naturally by fitting the concave and convex portions. become. In addition, when using the connector assembly, please use matting oil as necessary.
Enables connection with even more image loss - As explained above,
The connection method of the present invention is to process the core part in the direction of the original fiber [concave and convex, and engage the self-aligning effect tjt of the concave and convex parts,
Since it is possible to connect the 7-eye glass with accurate axis alignment, it is necessary to input the source from the end of the optical fiber and monitor the intensity of the source light emitted from the other end of the 7-eye glass while connecting the connection point. This enables connection of original fibers with low loss.

This connection is particularly effective for blind connections in one stack, such as connections at break points in submarine optical cables.In addition, because the original fiber is chemically treated, it also solves problems such as low strength at optical 7 eyep connection points. be able to·

[Brief explanation of drawings]

Figure 1 is a schematic diagram of Jourai's original fiber connection device, m2 figure) (C) is an illustration of the end face of the original fiber according to the embodiment of the present invention.
! ! It is a first view, and Figure 2 ←) is a convex M plane, Figure 2~)
indicates a concave end surface, and 2nd H (C) indicates a joint 11. Third
- is an etching characteristic diagram of quartz glass containing various dopants, FIG. 4 is an etching characteristic diagram of quartz glass original 7-eye glass containing GθQ, and a dopant (see FIG. 5) is an explanation showing the joining procedure in the present invention. Fig. 5 φ) is an explanatory view of the optical fiber m-plane according to the embodiment of the present invention, Fig. 6 is a cross-sectional view showing the valley 4 of the etching liquid, and Fig. 7 -) axis) is an explanatory diagram of the optical fiber m-plane according to the embodiment of the present invention. Fig. 8 is an external view of the optical fiber connector jigs used in another embodiment of the invention, 1 is the original fiber, 2 is the original fiber Fixed odor control, 3 is the electrode for arc, 4 is the tj connection connection monitor, the light receiver for the sFi connection monitor, the iFimMt point monitoring microscope, 11 is the core of the original fiber, 13 is the convex direction of the fiber, 14 is the concave direction , 15 is the butt splicing direction, 20a and 20b are the optical core ino (, 21 is the original fiber holding jig, 22 is the arc electrode for fusion, 401jVII board, 41#i holding plate, 42.43 is the original fiber, 50# Capillary for i-connection 〇 Patent issuer: Nippon Telegraph, Telephone Public Corporation agent, Patent attorney Mitsuishi Shibu (1 person) Relative refractive index difference An (~ Figure 4 (0) (b) Figure 6

Claims (2)

[Claims] (1) When optical fibers made of quartz glass and dopant-containing quartz glass are connected to each other at 1/kK, the quartz glass with a dopant is connected to the quartz glass. Immerse the quartz glass with the second etching solution to uniformly etch the quartz glass. Stirring friend he, both party fiber j! ! A method of connecting original fibers in which the characteristic is tII# joining with one direction facing each other. (2) The method described in Patent Claim 8 Turtle IJJ
When aligning the center of the optical 7 eyeglass, the original fiber s
s [Pure water, Al, alcohol, etc. &C immersion mat
What you need to do is to make the original fiber connection method.