JP2756150B2 - Optical coupling method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an optical coupling method between an optical element and an optical transmission line such as an optical fiber, and more particularly, to a method for coupling between a multi-terminal optical element and a plurality of optical fibers. Regarding alignment.

[Conventional technology]

There have been few reports on the method of aligning an optical element with a plurality of optical transmission lines (optical fibers), and there are only a few reports on optical systems such as those described in "Kato et al. Only the method of aligning the output end of the switch with the optical fiber has been reported.

The feature of this method is that optical fibers are aligned with each other by inserting a spherical fiber into a hole formed on a Si substrate using an anisotropic etching technique. This makes it possible to simultaneously perform the horizontal alignment (with respect to the light propagation direction) and the vertical alignment between the optical fibers, thereby facilitating the collective alignment of a plurality of optical fibers and optical elements. Further, since the position of the hole can be formed with high accuracy by lithography technology, the positioning accuracy is high.

[Problems to be solved by the invention]

In the prior art described above, by positioning the optical fibers with each other, it is possible to combine a plurality of optical fibers by collective adjustment. In this coupling method, the alignment (coupling) between the waveguide array of the optical element and the optical fiber array is performed by causing light to enter the optical element array from one end of the optical element waveguide and exiting from the other end. Is detected while detecting with an infrared TV camera. However, in this conventional method, it takes a lot of time and effort to join both ends. This is a major problem when trying to modularize the device.

In addition, the spacing between the waveguides of the optical element is often limited, and it has been difficult to adjust the x, y, z, θx _{, y, and z} directions with high accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for connecting an optical element and a fiber array as simply and as accurately as possible.

[Means for solving the problem]

In order to achieve the above object, light emission is caused in the waveguide of the optical element by some electric effect such as current injection.
Alternatively, a waveguide having the above-described light emitting function is provided, and the light-entering waveguide propagation light is detected by a fiber, so that the input end and the output end are simultaneously coupled.

Further, in order to achieve more accurate coupling, a waveguide for aligning the waveguide array and the fiber array, a fiber, and a pinhole guide for positioning the fiber are provided.
At least two coupling portions between the waveguide for alignment and the fiber are provided, and the two coupling portions (coupling portions) are separated from each other as much as possible to achieve high-precision coupling.

[Action]

Light emitted from the waveguide portion having a light emitting function in the optical element propagates simultaneously in the waveguide toward the entrance end and the exit end. The waveguide propagating light can be detected through the fiber by placing the fiber at the entrance end and the exit end. In other words, in contrast to the conventional one-sided coupling method in which light is incident on the incident end from a fiber that is to be coupled and the light is detected at the exit end, the fibers at both ends can be simultaneously adjusted, The time required for the connection can be reduced.

Further, the two coupling portions are useful for accurately correcting the positional deviation of the fiber array with respect to the optical element, particularly the deviation in the θ _{x, y, and z} directions. For this accuracy, it is more desirable that the interval between the joining portions for alignment is large.

〔Example〕

FIG. 1 shows an embodiment of the present invention. A carrier injection type 4 × 4 optical switch such as 1 is taken as an example of the optical element.

The fiber arrays 2 and 3 arranged so as to face the input and output ends of the optical switch are formed by forming holes for fiber positioning on a Si substrate by photolithography and anisotropic etching. By detecting the waveguide propagation light of the light emission generated by injecting the current into the switches 4 and 5 by the fibers 6, 7, 8, and 9 positioned by the fiber arrays 2, 3, θ
High-precision coupling without displacement in the _{x, y, and z} directions can be achieved. Further, since the alignment is performed by detecting the light emission, it is not necessary to input the light to the waveguide, and the coupling can be achieved simultaneously at the input and output ends.

The switch to be used can be arbitrarily selected.
However, if the distances between the waveguides used for alignment are set as short as possible, high-precision coupling becomes possible.

FIG. 2 shows another embodiment of the present invention. The feature of this embodiment is that the waveguide 10 is provided outside the optical element,
The fibers 14 and 15 fixed by the fiber arrays 11 and 12 are provided. In the above embodiment, the current must be injected into two switches (light emitting regions). According to the present embodiment, the current needs to be injected only into the switch 13, and the matching (coupling) can be performed more easily. It can be carried out.

FIG. 3 shows another embodiment of the present invention. Fiber arrays 11 and 12 are the same as in the previous embodiment.
This embodiment is characterized in that the light emitting regions 16 and 17 are provided in addition to the switch portion.
Is provided. In the case of the previous embodiment, the switch to be actually used must be kept ON during the adjustment. For this reason, there is a possibility that some influence will be exerted on the element characteristics.

According to the present embodiment, since a waveguide portion that does not affect switching is used, high-precision coupling can be achieved without deteriorating element characteristics.

FIG. 4 shows another embodiment of the present invention. The feature of this embodiment lies in that waveguides 22 and 23 having light emitting regions 20 and 21 are provided with an element interposed therebetween. In the above embodiment, the intensity of the light received by the fibers 6 and 8 passes through the branching portion, and therefore becomes smaller than the intensity of the light received by the fibers 14 and 15, which may make detection difficult. According to the present embodiment, the intensity of light detected by the fibers 24, 25, 26, 27 is substantially equivalent, and the interval between the fibers 24, 25 and 26, 27 for light detection is wider than in the previous example. High-precision coupling can be achieved more easily.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, since positioning between an optical fiber and an optical element can be performed simultaneously with an input / output end, the time required for mounting (coupling) can be reduced.

In addition, since the entire optical element is coupled using two coupling portions, highly accurate alignment can be easily performed.

[Brief description of the drawings]

FIGS. 1 to 4 are plan views showing optical coupling portions of an optical element and a fiber according to an embodiment of the present invention. 1: Optical element (carrier injection type 4 × 4 optical switch), 2, 3,
11,12,18,19 ... Fiber array, 4,5,13 ... Switch part (light emitting area), 6 ~ 9,14,15,24-27 ... Fiber, 10,22,
23: waveguide, 16, 17, 20, 21 ... light emitting area.

Continuation of the front page (72) Inventor Koji Ishida 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (56) References JP-A-63-163803 (JP, A) JP-A-59-143109 ( JP, A) JP-A-61-156205 (JP, A) JP-A-58-111109 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/42

Claims (5)

(57) [Claims] 1. A method of optically coupling an optical element having a plurality of waveguides and a group of optical fibers optically coupled to the waveguides, wherein the plurality of waveguides is any one of the waveguides. Due to an electrical effect, at least two places on one side of a plurality of end portions of the plurality of waveguides have a region that emits light such that light is emitted, and the light propagates from the predetermined waveguide by light emission. At least two locations on one side of the plurality of ends of the waveguide are detected through the optical fiber, and the positions of the optical element and the optical fiber group are adjusted based on the detected light at the two locations. Optical coupling method. 2. A method for optically coupling an optical element having a plurality of waveguides and an optical fiber group optically coupled to these waveguides, wherein the plurality of waveguides are any one of the waveguides. Due to an electrical effect, at least two locations on one side of a plurality of end portions of the plurality of waveguides have a region that emits light such that light is emitted. Integrally held by a pinhole guide made of a silicon substrate having a hole formed by reactive etching,
The light propagating from the predetermined waveguide of the light emission is detected through the optical fiber at at least the two locations on one side of a plurality of ends of the plurality of waveguides.
An optical coupling method, comprising: adjusting positions of the optical element and the optical fiber group based on detection light at a plurality of locations. 3. An optical coupling method for an optical device having a plurality of waveguides and a group of optical fibers optically coupled to the waveguides, wherein the optical device comprises: At least two locations on one side of a plurality of end portions of the optical device, the waveguide having a region that emits light such that light is emitted. This waveguide is different from the waveguide having the optical element function of the optical element. And detecting the light emitted from the predetermined waveguide through the optical fiber at least at one of two ends of the waveguide through the optical fiber, and based on the detected light, the optical element An optical coupling method comprising: adjusting a position of the optical fiber group. 4. The optical device according to claim 1, wherein the adjustment of the positions of the optical element and the optical fiber group is performed simultaneously at an incident end and an exit end of the optical element. Item 4. The optical coupling method according to item 1. 5. The optical coupling method according to claim 1, wherein said optical element is an optical switch.