JPH02266307A - Method for forming local conversion part of spot size of photoconductor - Google Patents

Abstract

PURPOSE:To form the local conversion part of spot size which utilizes heat diffusion efficiently by performing the local conversion of the spot size of the photoconductor by using a fine beam heating means. CONSTITUTION:Optical fibers 1 are positioned in V grooves 2a of a V groove substrate 2 and fixed to the V groove substrate 2 by electric field bonding or with a heat-resisting bond. Then the spot diameter of a fine beam 3 is reduced to about 100mumphi and made to scan at a specific position reciprocally to about 5 - 10mm width and thus the optical fibers are heated above 1,300 deg.C to diffuse dopant agents in the optical fibers, thereby expanding the spot size of the optical fibers 1 initially from 4.5mum to about 10mum. Thus, the local conversion of the spot size of the photoconductor can be performed by using the fine beam heating means such an electron beam and a laser beam from the flank or end surface of the photoconductor.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to optical fibers, semiconductor waveguides, and semiconductor waveguides used in optical communications.
The present invention relates to a method for forming a spot-sized local conversion portion that is extremely effective in reducing connection loss in an optical waveguide such as a dielectric waveguide.

(Conventional technology) The spot size of optical waveguides such as optical fibers and waveguides is
This is an important factor that affects connection loss between optical components, and it is being considered to locally increase the spot size between coupling end faces and device embedding areas to reduce connection loss and section loss.

As for such local conversion of the spot size of an optical waveguide, for example, the 1988 IEICE Spring National Conference,
C-457, as described in Yogami et al.'s "One method for configuring an optical fiber embedded device," the optical fiber is heated at 1300°C for 5 hours or more using a small heating furnace to diffuse the dopant inside. However, it has been confirmed that the spot size increases. In this case, the conversion section is required to perform tapered and smooth conversion.

(Problem to be Solved) As mentioned above, the conventional technology uses a small heating furnace to heat a portion of the optical fiber and induce thermal diffusion of the dopant agent in the optical fiber, thereby reducing the localization of the spot size. Conversion, - A tapered expansion is realized for boat fishing.

However, such a method has the following problems.

■It is sufficient for the local conversion length of the spot size to be several hundred Ilm, but when using a small heating furnace, it is difficult to locally heat such a short length.
It is necessary to heat it to about 0.00 mm.

■Normally, optical fibers have a plastic coating layer on the optical fiber glass, and this coating layer has no heat resistance, so in order to locally heat the plastic coating layer, it is necessary to It is necessary to remove more than twice the length.

(2) When using a small heating furnace, it is difficult to precisely control the heating distribution and temperature within, for example, several degrees.

(Means for Solving the Problems) The present invention provides a method for forming a spot size local conversion portion of an optical waveguide that solves the above-mentioned problems. The purpose of this method is to locally convert the spot size of an optical waveguide using a microbeam heating means such as a beam or a laser.

FIG. 1 is an explanatory diagram of a basic method of forming a spot size local conversion portion of an optical waveguide according to the present invention. Figure (A) is a perspective view of the optical waveguide arrangement, Figure (El) is a cut end view, Figure (C) is Figure (B)! , -X.

A cross-sectional view is shown.

The figure shows an example in which an optical fiber is used as the optical waveguide. As shown in the drawing, an optical fiber (
After positioning 1) and irradiating (4) the microbeam (3) to predetermined locations to expand the diameter of the spot size (Ilm), and then locally converting the spot size at the required locations. The optical fiber (2) and the grooved substrate (2) are simultaneously cut or grooved to predetermined dimensions to produce an optical coupling component with an enlarged spot size (lla) on the coupling end surface.

Note that the spot size of the optical waveguide (optical fiber) (1) is defined by the radius at which the intensity of the Gaussian wave becomes I/e2 at the center, and does not necessarily match the diameter of the core (11).

(Operation) FIGS. 2(A) to 2(C) all show examples of application of the spot size local conversion section.

In the same figure (A), the spot size of the optical fiber (A) is connected using a terminal device or an optical connector, etc. at the spot size local conversion parts (B) and (C) of the optical fiber (A). Small and strong against bending, bending, and lateral pressure. Same figure (
0) is an example in which a section embedded device (D) such as an optical isolator or an optical switch is inserted into the gap between the spot size local conversion section (A) of the optical fiber (A).
) is the local conversion part (
B) forms the attachment/detachment part, and the non-conversion part (E) forms the optical fiber (
This shows an example of direct connection in A).

Taking optical fiber as an example, its spot size is 5 μm.
Therefore, loss at the connection point has become a major problem. One solution to this problem is the development of high-precision optical connectors and optical couplers. This is based on accurately positioning and connecting optical fibers on the submicron order. In this way, optical connectors are required to have high precision on the submicron order when the spot size is 5! This is due to the fact that it is very small, about the size of a garden. In this way, the small spot size is determined by the manufacturing aspect and the transmission characteristics of bending and lateral pressure, but bending and lateral pressure mainly take into account the bending of the cable that occurs during installation, and the optical coupler The straightness of the optical fiber inside the optical connector is maintained, and it is preferable that the spot size is large within the optical connector.

Figure 3 shows a reference example of the relationship between the spot size gap (optical fiber butt gap) (d) and loss. The spot size can locally expand due to embedding of a device or separation of the end face of an optical connector, etc. It is extremely effective when used.

Local conversion of spot size has been reported as an example of thermal diffusion of dopants within an optical fiber, as described above. Generally 10
It requires heating at a temperature of 00°C or more for several hours or more, and is carried out in a small furnace. However, as mentioned above, when considering λ = 1 to 31 - communication for the local conversion part of the spot size, electron beam irradiation with a taper of several hundred μ■, CO□ laser heating, etc. are suitable, and the beam Diameter (spot diameter) 100j
It is effective to scan and heat around the intestine φ.

(Example) FIG. 1 and FIG. 4 are both explanatory diagrams of a method for forming a spot size local conversion portion using microbeam scanning.

As mentioned above, Figure 1 shows the V-groove (2a) of the groove substrate (2).
Position the optical fiber (1) inside the V-groove substrate (
2). Next, narrow down the spot diameter of the microbeam (3) to about 1001-φ, and place it at a predetermined position with a width of about 5 to 10
■■ Scan the optical fiber (1) back and forth between approximately 1300
Heated above ℃. As a result, the dopant agent inside the optical fiber (1) was diffused, and the spot size of the optical fiber (1) was expanded from the initial 4.5 m to about ILH.

In this experiment, the heating scanning time per location was completed in about 6 minutes. The substrate (2) was preheated to about 300"C. The relationship between the heating temperature and the heating time associated with spot size expansion depends on the diffusion characteristics of the dopant, but It is preferable to put this into practical use using an optical fiber containing a chemical agent, and the heating time can be shortened to several minutes or less.

By cutting the optical fiber grooved substrate (2) that has undergone local minute beam scanning into a predetermined size at the local conversion section and making it into chips, it is possible to obtain an optical component whose spot size is enlarged in the end view. It becomes possible.

FIG. 4(A) shows an optical fiber (N) from which the intermediate coating layer of the optical fiber core (10) has been removed is positioned and fixed on a V-groove substrate (2), and a minute beam (3) is scanned. ,
A method of forming a local transformer of sport/sport size is shown. In this embodiment, (1) a groove substrate (2) with stepped portions (2b) formed at both ends is used, and the coated portion of the optical fiber (10) is positioned on the stepped portion (2b);
Position the optical fiber (VIft,?!) in the V-groove of the board (2). Place the upper substrate (5) with the (5a) on the optical fiber (1) and glue it with adhesive (G). Grooved board (
2) Fix the optical fiber (1) and the upper substrate (5). In this state, the minute beam (3) is scanned at the window (5a) of the upper substrate (5) to form a spot size local conversion section.

Thereafter, by using a cutting groove processing grindstone (7) to form a groove (8) in the local conversion portion of the spot size, it becomes possible to embed an optical element there.

Figure m5 (a) and Figure 6 (a) both show an example of the forming method using the heating method. The heating distribution is necessary to create a local transformation of the spot size in the Taberon. Since heat conduction generally occurs, heating distribution will occur even with uniform irradiation by scanning as shown in Figure 5 (a) (see 4 at the top of the figure), but as a more aggressive method, it is possible to
, z-direction movement, or beam power adjustment, heating distribution by oscillating scanning as shown in FIG. 6(a) (4' in the figure) is also effective. In this case, although the focal position of the beam (3) is shifted in the height direction depending on the scanning angle, it becomes possible to positively form the heating distribution.

Figure 7 shows a minute beam (3) from the end face direction of the optical connector ferrule (20) with the optical fiber (+3) inserted.
FIG. 3 is an explanatory diagram of a method of forming a local conversion portion of the spot size by irradiating the spot size. Figure (A) is an overall schematic diagram, Figure (B) is a vertical cross-sectional view of the main parts, Figure (C) is an enlarged view of the end face, and Figure (D) is a vertical cross-sectional view of the completed optical connector ferrule. It shows.

By narrowing down the beam spot of the minute beam (3) to several 1 (H-φ), the center of the optical fiber (1) is irradiated (4
). The micro beam (3) is scanned circumferentially along the circumference of the optical connector ferrule (2G), and the optical connector ferrule (2G) on the outer periphery of the optical fiber (1) is scanned.
In this case, the material (for example, alumina ceramics or norconia) may be irradiated and heated, and the optical fiber (!) may be heated by the heat conduction. The adhesive (6) may be injected in a later process to polish the optical fiber several tens of times, or the adhesive (6)
6) may be used for temporary fixation, but in this case, the adhesive (8) near the end face evaporates due to heating, so it is necessary to resupply the adhesive (8).

Optical connector ferrule (20) obtained in this way
is as shown in Figure 7 (d), and the optical fiber (1) and spot size local conversion part (eye a) are shown as enlarged images, the optical fiber diameter is 125+intestine, and the optical connector ferrule diameter. The standard is 2.5 ■. Note that this technology can of course be used not only for the single-fiber optical connector ferrule as shown in the figure, but also for the formation of multi-fiber optical connectors, optical isolators, and optical switch embedded devices using silicon chips.

Figure 8 shows an example in which a part of the side surface of the optical fiber (1) is removed to make it flat (1a) and the microbeam is irradiated onto it in order to improve the heating efficiency of the microbeam (3). Figure (a) is a side view, and figure (b) is a sectional view taken along line IQ-XI in figure (a). In the experiment, irradiation was performed after removing the material to a depth of about 31 m.

Effectively reduces irradiation time. By changing the shape of this removal process, heating distribution can also be formed.

Figure 9 shows an example in which a heating absorption coating film is applied to the surface of an optical fiber to improve absorption of microbeam heating to improve heating efficiency and heating distribution. As shown in b), the heating distribution can be formed by changing the thickness of the heat-absorbing coat film (9) or by changing the material of the heat-absorbing coat film (9) depending on the position (9a3 (9b). Also, this method Usually, YAG laser (λ
= 1.06μ-) can improve the poor efficiency of heating quartz glass.

Figure 10 shows a local spot size conversion section by thermally diffusing a new diffusing substance (21) that acts on spot size conversion from the outside of an optical fiber (21) using microbeam (3) heating. Shows how to form.

In this case, as shown in Figures (A) and (0), it is preferable to coat the surface of the optical fiber (1) with a diffusing substance (21) by vapor deposition or the like. Furthermore, as shown in the same figure (0), the side surface of the optical fiber (IS) is processed into an arc shape (IS).
, it is effective to change the distance to the core part and form a spot size conversion taper part in conjunction with the beam scanning heating distribution. Incidentally, it goes without saying that the diffusion substance (21) may be coated or doped in advance on the outer periphery of the optical fiber or on the cladding portion near the outer periphery.

(Effects of the Invention) As explained above, according to the method for forming a spot size local conversion portion of an optical waveguide according to the present invention, the following effects are achieved.

■Spot size of electron beam, laser, etc. 1001■φ
By heating the optical waveguide using the following microbeam, it is possible to selectively heat a microscopic part of 1 to 2-width width and control the heating conditions with high precision, and local conversion of the spot size using thermal diffusion is possible. can be formed efficiently.

■ By performing oscillatory scanning of a small beam, the focal position is moved up and down and the oscillation is scanned once, making it possible to form a heating distribution in local heating and controlling the formation of a tapered part of the local conversion part of the spot size. can do.

■It is possible to precisely position an optical fiber on a silicon urchin/1-, etc., irradiate a minute beam to a predetermined location, and then cut it into a predetermined size to create an optical coupling chip with a spot size converter. Mass production and manufacturing of optical waveguide-embedded devices becomes easier.

(2) By removing a part of the side surface of the optical waveguide and irradiating that part with a minute beam, a spot size conversion part can be formed in a shorter time. It also effectively acts on the formation of a tapered portion of the converting portion due to heating distribution.

■By irradiating a minute beam from the end face of an optical connector ferrule, it is possible to form a spot size conversion part on the end face in the form of an optical connector.

(2) By coating the irradiation part of the optical waveguide with a minute beam heating absorption coat, it is possible to improve the heating efficiency and to form a heating distribution.

■ By providing a diffusive substance as a dopant on the outside or surface layer of the optical waveguide and irradiating it with a minute beam, it is possible to diffusely inject a new dopant agent from the outside or surface layer, and change the spot size. can be done.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the basic method of forming a spot size local conversion portion of an optical waveguide according to the present invention, in which (a) is a perspective view of the arrangement of the optical waveguide, and (b) is a cut end surface. Figure, the same figure (c) is of figure (0)! , -X is a sectional view. FIGS. 2A to 2C are explanatory diagrams of application examples of the spot size local conversion section. FIG. 3 is a characteristic diagram showing the relationship between the gap and loss of the spot size local conversion section. FIGS. 4(a) and 4(0) are explanatory diagrams of a method for forming a spot size local conversion portion using microbeam scanning. Figure 5 (a) is an explanatory diagram of local heating due to stage movement, figure (b) is a diagram of its heating distribution, and Figure 6 (a) is an explanatory diagram of a method of forming heating distribution by microbeam oscillation scanning. The figure (b) is a heating distribution diagram. Figure 7 is an explanatory diagram of a method for forming a spot size local conversion part by irradiating a microbeam from the end face of an optical connector ferrule, where (a) is an overall schematic diagram and (b) is a vertical cross-sectional view of the main part. , Figure (C) is an enlarged view of the end face, and Figure (D) is a longitudinal sectional view of the completed optical connector ferrule. Figure 8 shows a longitudinal cross-sectional view (A) of the optical waveguide with a part of the side surface removed in order to improve the heating efficiency of the microbeam, and a cross-sectional view of X*-X2 in Figure (A) (Fig. mouth). FIGS. 8(a) and 8(b) are both longitudinal cross-sectional views of a state in which a heating absorption coat is provided on a part of the outside of the optical waveguide in order to improve absorption of minute beam heating. FIGS. 10(a) and 10(+1) are both longitudinal cross-sectional views of a state in which a novel diffusing material is provided on a part of the outside of the optical waveguide. 1... Optical waveguide (optical fiber), 2... Grooved substrate,
3... Microbeam, 4... Microbeam irradiation section, 5.
... Upper substrate, 6... Adhesive, 7... Grindstone for processing cutting grooves, 8... Cutting grooves, 9... Heat absorption coating film, I
O... Optical fiber core wire, 20... Optical connector ferrule, 21... Diffusion material. +32 Figure U) d ()Jm) N44 Figure (A) Boiling A Figure Haunted

Claims (10)

[Claims] (1) In the local transformation of the spot size of the optical waveguide,
1. A method for forming a local spot size conversion portion of an optical waveguide, comprising locally converting the spot size of the optical waveguide using a minute beam heating means such as an electron beam or a laser from a side surface or an end surface of the optical waveguide. (2) A local conversion unit for the spot size of the optical waveguide according to claim (1), characterized in that the minute beam is continuously moved back and forth in an arc shape, and the heating distribution is adjusted using vertical movement of the focal point position. Formation method. (3) Local conversion of the spot size of the optical waveguide according to claim (1), characterized in that the spot size local conversion portion of the optical waveguide is provided with a heat absorption coating film for improving heat absorption of the minute beam. Part formation method. (4) The method for forming a spot size local conversion portion of an optical waveguide according to claim (3), wherein the heating distribution is adjusted by changing the thickness or material of the heat-absorbing coating film. (5) Claim (1) characterized in that the optical waveguide is combined with a substrate, and the optical waveguide is locally heated by applying microbeam heating to a specific location on the substrate and utilizing heat conduction from the substrate.
) A method for forming a spot size local conversion portion in an optical waveguide. (6) A material layer that acts on spot size conversion is provided on the outside of the optical waveguide, and the spot size conversion is locally realized by diffusing the substance into the optical waveguide during the microbeam heating process. A method for forming a spot size local conversion portion in an optical waveguide according to claim (1). (7) The optical waveguide is composed of optical fibers, a plurality of them are fixed on a substrate, and after irradiating a minute beam from the top surface to the required location to perform local conversion of the spot size, the optical fibers and the substrate are connected. Optical waveguide according to claim (1), characterized in that by simultaneously cutting or grooving to a predetermined size in the spot size local conversion section, an optical component chip in which the spot size of the coupling end face is locally converted is obtained. A method for forming local transformations of spot size on the body. (8) The optical waveguide is composed of optical fibers, one or more of which is positioned and fixed in the optical fiber guide hole of the optical connector, and a minute beam is irradiated from the end face of the optical connector to a spot on the end face of the optical fiber. 2. The method of forming a local spot size conversion portion of an optical waveguide according to claim 1, wherein the spot size of the optical waveguide is changed. (9) Local spot size of the optical waveguide according to claim (1), characterized in that the optical waveguide is constituted by an optical fiber, a part of the side surface thereof is removed, and a minute beam is irradiated to that part. Method for forming a conversion part. (10) The method for forming a spot size local conversion portion of an optical waveguide according to claim (3), wherein the temperature distribution is formed by minute beam heating using the removed shape of the side surface as a parameter.