JPS6041526Y2 - waveguide interface - Google Patents

Description

[Detailed description of the invention] The present invention relates to an optical transmission element, in particular, a plurality of optical fibers (optical fiber array) for connection with an external optical circuit, and a plurality of three-dimensional fibers formed on the surface of a waveguide substrate. It relates to a waveguide interface that couples waveguides (waveguide arrays).

In recent years, waveguide interfaces such as those described above have attracted attention as optical transmission elements.

In such a waveguide interface, the coupling between the optical fiber array and the waveguide array is a decisive issue that determines its fate.

However, the cross-sectional shapes of optical fibers and waveguides have minute dimensions on the order of μm, making coupling between the optical fiber array and the waveguide array extremely difficult.

Conventional coupling methods generally involve precisely arranging optical fiber arrays on a substrate, then abutting the end faces of the optical fiber array and waveguide array, and bonding and holding the optical fiber array and the waveguide array by adhesion.

However, with this method, it is extremely difficult to precisely arrange the optical fiber array and align the optical fiber array and the waveguide array, making it difficult to achieve high optical coupling efficiency and requiring a large amount of manufacturing time (assembly time). There were problems in terms of productivity and cost.

Therefore, the purpose of the present invention is to solve the above problems, that is, to easily enable accurate coupling between an optical fiber array and a waveguide array, thereby achieving high optical coupling efficiency, high productivity, and low cost. The object of the present invention is to provide a waveguide interface having such a structure that it can be used.

The waveguide interface according to the present invention can be summarized as follows.
The optical fibers are arranged by fitting into grooves formed on the surface of the common substrate in correspondence with the waveguides, and alignment protrusions that can be fitted to each other are provided on the surface of the waveguide substrate and the surface of the common substrate. and grooves are formed, respectively, and the waveguide substrate is configured to be installed on a common substrate with the respective surfaces facing each other and the positioning protrusions and grooves being fitted.

Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the waveguide interface according to this issue in an exploded state.

This waveguide interface basically consists of multiple optical fibers 1 (1) for connection with an external optical circuit (not shown).
(Only two pieces 1a and 1b are shown in the figure), a waveguide base 2, and a common substrate 3.

In FIG. 1, the optical fiber 1 is shown enlarged from other elements for clarity, and the waveguide substrate 2 is shown in a perspective view from the surface (bottom surface) on which the waveguide is made for clarity. This is an indication.

The waveguide substrate 2 is made of, for example, lithium niobate (LiNbO3
), gallium arsenide (GaAs), etc., and there are multiple waveguides 4 (two in the figure) on its surface (lower surface in the figure).
Waveguides 4a and 4b (indicated by dotted lines) are fabricated.

The waveguide 4 is made by doping the waveguide base 2 with, for example, chromium (Cr), and has the function of confining and transmitting light similarly to an optical fiber.

The common substrate 3 is a member for coupling and holding the optical fiber 1 and the waveguide base 2, as will be described later, and is made of silicon, quartz, glass, etc., for example.

Two grooves 5 (a,
b) is made to correspond to the waveguide 4.

These grooves 5 are for fitting and aligning the optical fiber 1, as will be described later, and will be hereinafter referred to as one optical fiber groove.

Also, on the surface of the common substrate 3, two fR6 (at b) are formed on both sides with the optical fiber groove 5 interposed therebetween.

On the other hand, on the surface of the waveguide substrate 2, there are two protrusions corresponding to the grooves 6. (at b) is pronounced.

These grooves 6 and protrusions 7 are for fitting into each other to align the waveguide base 2 with respect to the common substrate 3, as will be described later.

The above-mentioned optical fiber groove 5, alignment groove 6, and protrusion 7 can be precisely and easily formed using photolithography technology, etc., so that the optical fiber 1 and the waveguide base 2 can be precisely formed as described later. positioning becomes possible.

Although the grooves 5, 6 and the protrusion 7 have a rectangular cross section in FIG. 1, they may have any suitable shape such as a square square shape.

Further, the coupling side end face of the optical fiber 1 is polished obliquely at an appropriate angle (approximately 45° in the illustrated example) with respect to the optical axis, and the end face of the waveguide 4 is also polished obliquely in accordance with this.

Now, FIG. 2 is a sectional view of essential parts of the waveguide interface shown in FIG. 1 in an assembled state.

As is clear from this figure, the optical fibers 1 (only the optical fibers 1a are shown in FIG. 2) are arranged so as to fit into the optical fiber grooves 5 of the common substrate 3.

This allows the optical fiber 1 to be accurately positioned on the common substrate 3.

The optical fiber 1 is arranged so that the inclined end face faces downward, and for example, the light 8 that enters from the connection end of the optical fiber 1a with the external optical circuit (the left side in the figure) is reflected by the inclined end face and is emitted upward. do.

On the other hand, the waveguide substrate 2 is installed on the common substrate 3 with the surfaces thereof facing each other and the positioning groove 6 and the protrusion 7 fitted together.

As a result, the waveguide base 2 is positioned with high precision with respect to the common substrate 3, and as a result, the waveguide 4 is accurately coupled to the optical fiber 1.

The optical fiber 1 and the waveguide 4 are coupled with their ends vertically overlapping as shown in the figure, and the light emitted from the optical fiber 1a is reflected by the inclined end face of the waveguide 4 and transmitted to the other end.

and the other end of the waveguide 4 and the optical fiber 1 that couples it together.
The light beams are reflected by the inclined end faces of b and are emitted from the other end of the optical fiber.

As described above, since the optical fiber 1 is accurately positioned on the common substrate 3 by the optical fiber groove 5, and the waveguide 4 is accurately positioned on the common substrate 3 by the positioning groove 6 and the protrusion 7, the result is Accurate coupling between the optical fiber 1 and the waveguide 4 can be obtained very easily, and therefore high optical coupling efficiency can be achieved, as well as high productivity and low cost due to mass production.

In the embodiment shown in FIGS. 1 and 2, the coupling side end surfaces of the optical fiber 1 and the waveguide 4 are polished obliquely to the optical axis, and the ends of the two are overlapped one above the other. Although it is assumed that the state is used for coupling, other coupling methods are also possible.

An example of this is shown in FIG. 3 in correspondence with FIG. 2.

In this example, the optical fiber 11 and the waveguide 1 of the waveguide base 12 are
The coupling side end faces of No. 4 are polished perpendicularly to the optical axis, and the two end faces are butted against each other and coupled.

For this purpose, the optical fiber groove 15 of the common substrate 13 is made shallower than the diameter of the optical fiber 11, so that only the bottom of the optical fiber 11 fits into the groove 15, and the optical fiber 1
The optical axes of the waveguide 1 and the waveguide 14 are made to substantially coincide in the vertical direction.

Therefore, the optical path of the light 18 is approximately straight.

The coupling method of this example is difficult to apply when the diameter of the optical fiber and the diameter of the waveguide are approximately equal, but is easy to apply when the diameter of the optical fiber is larger than the diameter of the waveguide.

As described above, the present invention realizes an excellent waveguide interface that provides high optical coupling efficiency, high productivity, and low cost, and greatly contributes to the development of optical transmission technology.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of the waveguide interface according to the present invention, FIG. 2 is a sectional view of the main parts of the embodiment shown in FIG. 1 in an assembled state, and FIG. 3 is another embodiment of the present invention. FIG. 1(at b)t 1111a*ells optical fiber, 2, 12... Waveguide base, 3, 13...
...Common substrate, 4(at b)t 14"" waveguide,
5 (at b), 15... groove (optical fiber groove), 6 (at b)... groove, ? (at
b)... Protrusion, 8... Light.

Claims (1)

[Scope of utility model registration request] In a waveguide interface that couples multiple optical fibers for connection with an external optical circuit and multiple three-dimensional waveguides formed on the surface of a waveguide substrate, the optical fibers are connected to a waveguide on the surface of a common substrate. The waveguide substrate surface and the common substrate surface are respectively formed with alignment protrusions and grooves that can be fitted to each other, A waveguide interface characterized in that the waveguide interfaces are arranged on a common substrate with their respective surfaces facing each other and the positioning protrusions and grooves being fitted.