JPH0375708A - Optical unit and optical coupling part thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an optical unit in which a holder for an optical waveguide and a holder for an optical component are laser welded via a brazing material, and an optical coupling part thereof, particularly for low-power These holders can be joined using laser light.

<Conventional technology> In recent years, with the advancement of technology in fields such as optical communication and optical information processing, it has become possible to implement highly reliable optical fibers for single mode transmission and optical waveguides that constitute optical coupling circuits, optical branching circuits, etc. It has become necessary to do so. As is well known, the diameter of the core portion of a single-mode transmission optical fiber is only about 10 μm, and when connecting this single-mode transmission optical fiber to the optical waveguide described above, the relative It is necessary to suppress the positional deviation to about 1 μm or less to prevent an increase in connection loss.

Conventionally, when connecting an optical waveguide and an optical component such as an optical fiber for single mode transmission, the holder that holds the optical waveguide and the holder that holds the optical component are positioned so that the connection loss between them is minimized. Both are fixed with adhesive.

However, this method requires the pair of holders to be fixed in a stationary state until the adhesive hardens, and there are problems with the characteristics of the adhesive against the external environment, so it cannot necessarily be said to be highly reliable. Ta.

Therefore, it is being considered to apply laser welding, which has less thermal influence on the surroundings and can perform instantaneous joining, to the joints between these optical waveguides and optical components. As shown in FIG. 7, which shows an example of an optical unit having such an optical coupling part, the connecting end of a single mode transmission optical fiber (hereinafter abbreviated as single mode fiber) 101 is made of stainless steel. Stainless steel holder 1 via ferrule 102
It is buried in 03. The single mode fiber 101
An optical waveguide 104 whose one end side is connected to is adhesively fixed to a stainless steel holder 105.
04 has a sensor chip 106 assembled therein. At the other end of this optical waveguide 104, a plurality of (two in the figure) multimode transmission optical fibers (hereinafter abbreviated as multimode fibers) are held in a stainless steel holder 107.
108 are connected, and the holder 107
is attached to a holder receiver 109 made of stainless steel. The abutting ends 110 of these holders 103, 105° 107 and holder receiver 109 are appropriately spot welded using a YAG (yttrium aluminum garnet) laser and are integrated with each other.

The light incident from the single mode fiber 101 is split into two by an optical waveguide 104, and the light is beamed into two multimode fibers 108, one on the side with the sensor chip 106 and the other on the other side. Therefore, by comparing the outputs from these two multimode fibers 108, various highly sensitive measurements based on the sensor chip 10B become possible.

<Problems to be Solved by the Invention> In the conventional optical unit and its optical coupling part shown in FIG. The depth must be set sufficiently deep. Moreover, since the holders 103, 105, 107 and the holder receiver 109 that are joined to each other have a block shape with a large heat capacity, a high output Y
It is necessary to use an AG laser.

However, the transmission tolerance limit of conventional energy beam transmission optical fibers that can guide high-power YAG lasers is only about 30 units, and for higher-power laser beams, a reflector is used. It was necessary to adopt a multi-jointed guide device, which had the disadvantage that it was troublesome to handle the 11 m long guide device. Furthermore, when a high-power laser beam is irradiated to the welding area, the impact of the welding at this time causes the relative positions of the holder 103, 105, 107 and the holder receiver 109 to shift, resulting in an increase in connection loss. there were.

Means for Solving the Problems> An optical unit according to the present invention includes an optical waveguide, an optical component connected to the optical waveguide, a pair of holders that respectively hold the optical waveguide and the optical component, and a pair of holders for holding the optical waveguide and the optical component, respectively. A device characterized by comprising brazing metal holding portions formed at the butt ends facing each other, and brazing metal holding portions each integrally embedded in each of the brazing metal holding portions and laser welded to each other. It is.

Further, the optical coupling unit according to the present invention is an optical coupling in which a holder holding an optical waveguide and a holder holding an optical component connected to the optical waveguide are abutted against each other, and the abutted ends of these holders are integrally joined. brazing material holding portions are formed at the abutted ends in a mutually opposing state;
It is characterized in that the brazing filler metals each integrally buried in each of these brazing filler metal holding parts are laser welded to each other.

The melting point of the brazing filler metal is low enough for the holder that holds the optical waveguide or optical component, so it is not possible to use a low-power laser beam on the brazing filler metal that is integrated with the brazing filler metal holder formed at the butt end of the holder. These brazing filler metals are joined to each other with a sufficient depth of melting even when used, and the pair of holders are integrated.

Embodiment As shown in FIG. 1 showing the appearance of an embodiment of an optical unit having an optical coupling part according to the present invention, and FIG. 2 showing its cross-sectional structure, a A ferrule 12b made of ceramics, metal, etc., such as Silconi 1, whose one end is fitted into a guide sleeve 12a made of metal such as stainless steel, is integrally fitted, and a part of the guide sleeve 12a and the ferrule 12b is joined in a penetrating state to a metal holder 13 made of Kovar or the like which has good joining properties with a brazing filler metal to be described later.

A metal holder 15 having an optical waveguide 14 connected to the single mode fiber 11 at one end is bonded to the holder 13 .

As shown in FIG. 3 showing the structure of the optical waveguide 14, the optical waveguide 14 of this embodiment includes a core portion 14a connected to the single mode fiber 11 and branched into eight pieces by a Y branch circuit;
It consists of a cladding part 14b surrounding the core part 14m and a substrate 14c holding the cladding part 14b, and the substrate 14c part of the optical waveguide 1114 is integrated with the holder 15 with an adhesive (not shown). Note that this optical waveguide 14
and the holder 15. As a bonding method, a metal film is formed on the bonding end surface of the optical waveguide 14 to the holder 15 by vapor deposition or the like,
It is also possible to braze the optical waveguide 14 and the holder 15 via this metal film. As an aside, this thin film optical waveguide 14 can be formed by the method disclosed in Japanese Patent Publication No. 61-39645, etc., and can be formed using multicomponent glass, lithium niobate, quartz glass, or various semiconductors. This optical waveguide 14 is constructed by the following.

As described above, in this embodiment, the optical waveguide 1114 using a Y branch circuit is employed, but the optical waveguide 14 using a directional coupling circuit as shown in FIG. 4 or a wavelength-independent circuit as shown in FIG. It is also possible to employ an optical waveguide 14 that utilizes the optical waveguide 14, and in short, it is sufficient as long as the optical waveguide has one or more input ends and one or more output ends for the optical signal.

In addition, in these FIGS. 4 and 5, members having the same functions as those shown in FIG. 3 are designated by the same reference numerals.

In this embodiment, the eight single mode fibers 16 whose connection ends are respectively connected to the other end of the optical waveguide 14 are fixed by a fiber receiver 17 and a fiber presser 18 that hold these connection ends at regular intervals. These are further bonded to a metal holder 19 via an adhesive.

The holders 15 and 19 are made of Kovar or the like, which is the same material as the holder 13, and the joints of their abutted ends 20 are filled with low melting point solder 21 such as eutectic solder. . These low melting point solders 21 are spot welded using a YAG laser or the like, but since the heat capacity of these parts is small, if the energy of about 5 units is irradiated with pulses of 1 to 10 milliseconds, sufficient weld penetration depth can be achieved. You can get the feeling.

By the way, the butt ends 2 of the holders 13, 15, 19
In order to directly laser weld 0 and obtain the same penetration depth as in this example, an energy of 30 units or more must be applied to 1~1
It is necessary to irradiate with a pulse of 0 milliseconds, and by adopting the structure of this embodiment, it becomes possible to use a low-output YAG laser.

As a method of irradiating the low melting point solder 21 with laser light, the single mode fibers 11, 16 and the optical waveguide 14 are simultaneously irradiated from three locations T1 at 180 degree intervals, sandwiching the single mode fibers 11, 16 and the core portion 14m of the optical waveguide 14. Two laser beams are irradiated towards 14, and the impact during welding causes the
It is desirable to take care so that the relative positions of the holders 13, 15, and 19 do not shift.

When filling the butt ends 20 of the holders 13 and 15° 19 with this low melting point solder 21, first
,15. ．． 19 are temporarily assembled, and in this state, a hole is made with a drill or the like at the butt end portion 20 where the low melting point solder 21 is to be filled. 19 at the abutting end 20. Next, the holders 13 and 15° 19 are disassembled, and a low melting point solder is applied to the semicircular groove-shaped filler holding portion 22 formed at the butt end portions 22 of these holders. 21, the surface of these low melting point solders 21 is polished to form the holders 13, 1.
It is made to be flush with the surface of the abutting end portion 22 of Nos. 5 and 19. And these holders 13, 15, 19
The holder 13,
15 and 19 are integrated.

In this example, a low melting point solder t! which does not have very high mechanical strength was used as the brazing material. 21, it is not suitable under usage conditions where there is a risk of being subjected to a large external force. In such a case, as shown in FIG. 6, which is an enlarged view of the abutting ends 20 of the holders 15 and 19 in FIG.
．． The joining strength of the holders 13, 15, and 19 can be improved by directly laser welding the abutting ends 20 of the holders 19 to form the portion 23, or by using a high-strength hard brazing material or the like.

<Effects of the Invention> According to the optical unit and the optical coupling portion thereof of the present invention, since the pair of holders that are butted against each other are laser welded through the brazing material embedded in the butted ends, the cost is low. Sufficient penetration depth can be obtained even with high output laser light, and equipment costs can be reduced. Furthermore, since the impact when irradiated with laser light can be reduced, it is possible to easily realize an optical unit having a low-loss optical coupling section. Furthermore, if an increase in splice loss is observed after laser welding the filler metal, it is easy to heat the filler metal again, disassemble the holder, reassemble the holder, and join them together. This is very effective as a relief measure when implementing circuits with poor yields where only one optical circuit can be fabricated per unit.

[Brief explanation of drawings]

FIG. 1 is an external perspective view showing an embodiment of an optical unit equipped with an optical coupling section according to the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3 to 5 are examples of the structure of the optical waveguide. FIG. 6 is a partially enlarged perspective view showing another embodiment of the present invention, and FIG. 7 is an external perspective view showing an example of an optical unit having a conventional optical coupling portion. Also, in the figure, 11.16 is a single mode fiber, 1
2b is a ferrule, 13, 15.19 is a holder, 14 is an optical waveguide, 14a is a core portion, 14b is a cladding portion, 14
c is a substrate, 17 is a fiber receiver, 18 is a fiber holder,
20 is a butting end, 21 is a low melting point solder, 22 is a brazing material holding part, and 23 is a direct attachment part. Figure +4b Figure 40

Claims (4)

[Claims] (1) An optical waveguide, an optical component connected to this optical waveguide,
A pair of holders that hold these optical waveguides and optical components, a brazing metal holding part formed at the butt ends of these pair of holders in a mutually opposing state, and a brazing metal holding part integrally embedded in each of these brazing metal holding parts. and a brazing material that is laser-welded to each other. (2) In an optical coupling section in which a holder holding an optical waveguide and a holder holding an optical component connected to the optical waveguide are abutted against each other and the abutted ends of these holders are integrally joined, the abutted end 1. An optical coupling unit characterized in that brazing metal holding portions are formed in such a manner that they face each other, and the brazing metal holding portions are integrally embedded in the brazing metal holding portions and are laser welded to each other. (3) The optical unit according to claim (1), further comprising a direct attachment portion formed at the abutting ends of the pair of holders and directly laser welding the abutting ends. (4) The optical coupling part according to claim (2), further comprising a direct attachment part for directly laser welding the abutted ends of the holder.