JPS5834408A - Manufacture of optical plain surface circuit - Google Patents

Abstract

PURPOSE:To form an optical plain surface circuit having a branching and junction part having less scattering loss, by making the refractive index distribution in a sectional direction of an optical waveguide into a graded distribution by an ion exchange method. CONSTITUTION:A part corresponding to an area forming an optical waveguide on a substrate 1 is exchanged by the ion contributing to enlarge a refractive index to form a high refractive index layer. Then, the unnecessary part of the high refractive index layer is removed by etching to form a prescribed optical waveguide pattern 2. Afterwards, the surface of the pattern 2 is exchange by the ion contributing to make a refractive index small and the distribution in which the refractive index in a section of the waveguide 2 is high in the center and is decreased as it goes to the circumference is given. Thus, by making the refractive index distribution in a sectional direction of the optical waveguide into a graded distribution, an optical plain surface circuit having a branch and juction part having less scattering loss is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical circuit, and particularly relates to a method for manufacturing an optical circuit, particularly branching, merging, or any of the above. 1X11) In order to create a t-direction circuit with functions such as a star coupler (41), (
1) We will focus on methods for manufacturing optical circuits that are easy to use.

The so-called optical plane circuit that provides various functions is used in fields such as optical communication bi and Maru information system (kookeru small oar).
It is suitable for use as an optical circuit.

The 11 methods for manufacturing conventional r(H plane circuits) include - high frequency sputtering, CVD, L, and ion exchange methods. - 1. The high frequency sputtering method of l'IJ1 This method sputter-vaporizes the five-pronged melon that is to become a waveguide, but since the IWJ atoms are difficult to combine uniformly and in (a), the transmission loss due to randomization is large (8). The second CV I) method is to deposit this CVD onto the substrate.
The oxidized proboscis particles are deposited by the method, and this is heated to form a transparent glass film.The desired pattern is formed by active sputter etching of the glass film for the core. After that, a clad glass (11; , has the advantage that the lid waveguide pattern can be formed arbitrarily, but one of the core patterns is
- Tsuching surface J-ft-B core iζ and Ri (2) The part that becomes the boundary with the land part has an unevenness of 11", and the scattering loss in this part increases. Also, the sixth ion exchange method is an embedded optical/waveguide σj f!), and the optical loss is U, [J 1 (IB / (:nl) is as small as a leech < s Tomari'ji 4J1. 'J In this method, a patterned mask is provided on the surface of the fr substrate, and the protruding portions of the substrate, that is, the pattern Iil l-j f・r-ions contributing to ion exchange with ions in the substrate,
Furthermore, after that, the surface is exchanged with ions contributing to the low refractive index (this is the usual way to create a guide structure.
According to this ion exchange method, the cross-sectional shape of the 4-wave path has a larger spread in the direction of growth on the substrate surface than in the depth direction. Precisely forming a person becomes more personable.
Rico-f 7 parts (The size of the corresponding part changes at that part, and the loss at this branch part increases.

The present invention has been made in view of the above problems, and includes:
For example, a dielectric wall plate made of glass, etc. - corresponding to the region forming the circle z4 wave path Be1-min, -,, II+,! An ion that contributes to increasing the refractive index, such as an ion, exchanges with an ion in the substrate glass to form a high refractive index 1-, and the anxious part of the refractive index 1'J is written as -, for example. The desired optical waveguide pattern is formed by using reactive sputter etching method etc. using VC (moxibustion, its surface is 1 (ion-)). The distribution of the 410 Jt ratio in the cross section of the optical waveguide is oriented at the center and decreases toward the periphery. That's 1 ru. According to the present invention, it is possible to obtain an optical plane circuit having a branching portion or a convergence portion having an angle of 18° and having a small loss. J-i.e.
i'A sentence, f, ll] 4: In order to form an optical waveguide pattern, a high shield IW shape is formed by etching (on top of that, the etching IY caused by the above etching and the influence of scattering loss due to small irregularities etc. In order to eliminate this, the surface is exchanged with ions that help reduce the refractive index.
It has a kite structure with a graded refractive index distribution.

In the present invention, if a JHI refractive index distribution type lens is disposed on the above substrate and at the end of the optical waveguide, this /fit refractive index distribution type lens can produce light. The light rays from the fiber etc. are efficiently directed to the optical waveguide, and the whole beam emitted from the optical waveguide is directed to the original fiber or photodetector Hesbot shape.Using this gradient index lens According to the above), even when the cross-sectional shape of the waveguide structure is multi-mode, it is sufficient to have an angle of about 15 to 20 μm. In other words, when considering an optical waveguide structure, its cross-sectional shape (dimensions)
In the case of a single mode, an iff of about 10μ is sufficient, but in the case of a multimode, an iff of about 50μ is required. Therefore, when reactive sputter etching is used as the etching method as described above, the etching rate is at most 0.1 μ/#, and it takes too much time to form a multimode optical waveguide, which is not very economical.

However, by arranging the L gradient index lens,
The cross-sectional shape of the optical waveguide may be small, and the above problem can be solved.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Note that the processing examples shown here are merely illustrative of the present invention, and the present invention is not limited thereto.

Detailed example 1. > Here, a case in which a gradient index lens is provided will be described. FIG. 1A conceptually shows a branch or merge circuit. In other words, the optical plane circuit of this embodiment has a substrate (1)-
By forming the optical waveguide section (2) and the gradient index lens section (3) as an optical coupler together, the input and output of the light beam can be carried out efficiently and easily. FIG. 13 shows a plan view (y-z axis of the coordinate axes shown in FIG. 1A) of the lens portion (3) and the wave path portion (2). The hll refractive index distribution of the lens part (3) of this circuit is the first
As shown in Figure C, the jiTl refractive index distribution of the waveguide section (2) is as shown in the first diagram.

Next, FIGS. 2 to 6 show the manufacturing process of the above circuit. First, as shown in Figure 2, a substrate such as glass (
A film of TI or AI is formed on the surface of 1) by high-frequency sputtering, and then using known photolithography, an opening (force is applied) is formed at the position where the lens portion (3) and the optical waveguide (2) are to be formed. Then, from the surface, for example, 'J'e
(Ion exchange with ion (8) that contributes to increasing the IJ, d refractive index, and the lens part (9) and high strength +I 41? index In tlQ) as shown in Figure 6)
Then, swim away the mask (6). None, here, 1140 (7) and the end of the waveguide (2) formation area do not necessarily have to be connected, and the required refraction overlap is 1.
The distance between the two can be set to 1 depending on the size of the i-type lens (3) and lens performance. (The force does not necessarily have to be circular, and the required +f[t 4
It can be formed into an elliptical shape or the like in accordance with the shape of the Jr rate distribution lens portion (3).

Next, as shown in FIG. 4, for example, an amorphous silicon film is formed on the surface of the substrate by high-frequency sputtering or the like, and the amorphous silicon film is etched using the liquid Cl5rF5 gas or by active sputter etching. A mask 111) is formed to form a desired line-shaped electric waveguide pattern.

Of course, at this time, the lens forming area is defined by the mask (11). After that, the exposed long side of the board is now If
The desired pattern (12
1 (Figure 5). Then, the mask was removed using the same etching method as for the upper part, and the line-shaped waveguide pattern U and the lens part E obtained as above were added.
The surface of 191 was ion-exchanged with 7T (14J) to contribute to reducing the refractive index as shown in Figure 6, and the patterned single-line waveguide (
121 as a guide structure, and the lens f<519
1F embedded type. here,! ■As shown in Figure 6, by providing a thin mask (+++1) on the upper surface of the channel-shaped optical waveguide (12) and a small mask (+++1) on the lens part, the mask 1, nod-shaped -#, waveguide (2) and lens (31 Both are in the X-axis direction (from which a graded distribution can be achieved).

In this way, an optical planar circuit equipped with an optical coupler as shown in FIG. 1 is obtained. As shown in the first diagram, the refractive index distribution in the X-axis direction or the y1qtl direction of the single exposed optical waveguide (2) becomes fi
11 refractive index gradually decreases, for example, by square approximation, resulting in a chevron-shaped distribution as a living body. Therefore, as shown in FIG. 1B, the light bA (5) in the waveguide (2) travels in a meandering manner before reaching the next curve, and is directed toward the etching process, which attempts to create "C unevenness". political disturbance losses will be reduced.ft, oz4!l+1
There is no change in bending or f-factor in the direction. - Also, FIG. 1C shows the refractive index distribution of the gradient index lens (3) in the x+lq1 direction or the x2 direction.1. As the distance from the central axis increases, the refractive index gradually decreases, for example, by square approximation, resulting in an overall mountain-shaped distribution.

Note that y @ force direction Jif (refractive index distribution is Z tllllll
It's about the same size.

In the manufacturing process of the embodiment described above, the optical waveguide portion (2) and the gradient index lens are buried by 11 μm of 3) deeper than the surface of the substrate (++, the ion exchange time is accelerated, or the refractive index lens is In order to select the shape of the outer index cloth, etc., an ion diffusion process may be performed by applying a field.Also, in the practical example mentioned above, the gradient index lens is
Although only one is formed, two or more may be formed. 7th
As shown in the figure, a large number of gradient index lenses (3) and optical waveguide sections] (21 can be formed on one substrate +11.The substrate (1) and a silicon substrate for good connection of optical fibers (21) can be formed on one substrate +11. 16) and 4 common fibers (1 frame) are bonded to each other.Furthermore, 4 fibers (1) are formed on the substrate (1) and held on the V-groove side.

In such a circuit, 114! The size, lens performance, relative position of each of the above-mentioned refractive index lens portions (3), the shape of the electric waveguide portion (2), etc. are selected arbitrarily and with high precision depending on the shape of the mask. It is possible,
East (h version 01 can be done easily.

If the real moderation G is applied as in the case of V1 in the first trial, it is possible to form a bifurcation pattern (2) or confluence pattern (2) with 1 (support) accuracy in the darkened substrate m, and also to improve the refractive index distribution as described above. type lens (3
) That is, by providing optical couplers on the same substrate (1), a multimode optical branching/combining element can be manufactured at low cost.

<Embodiment 2> This circle 1 fabric example is used to form a Y branch circuit using a single mode optical waveguide. FIG. 8A shows the Y branch circuit of this actual example. Ll:Ir of the optical waveguide of this circuit
The surface 14-shaped L + (+1) refractive index distribution pattern is as shown in Figure 8.The manufacturing process is as shown in Figure 2. 6), first, the surface of the substrate (1) is ion-exchanged with ions that contribute to increasing the refractive index to a depth of 3 to form a flat refractive index layer. 19. Form a mask for the desired Y-branch pattern on the surface, remove unnecessary parts of the substrate by reactive sputter etching, etc.
An optical waveguide pattern (2) with a (411' index) is formed.Furthermore, a new ion material that contributes to reducing the refractive index of the surface of the above pattern is ion-exchanged with ions of the substrate composition. A light guide structure, i.e.
Since the optical branching pattern (2) is formed by etching, the shape of the branching pattern can be manufactured with high accuracy, and a branching pattern with small loss at the branching point can be obtained. Furthermore, since the surface of the pattern is later ion-exchanged with ions that contribute to lowering the refractive index to create a guide structure, the effect of scattering loss due to minute irregularities on the etched surface caused by -1: etching is reduced. It's suppressed.

Here, the refractive index distribution of the optical waveguide (2) gradually decreases as it moves away from the first central axis, similar to, for example, the second central axis, resulting in an overall mountain-shaped distribution. Note that there is no change in the JII+ refractive index in the Z-axis direction.

As I said, according to the example of this book, Taomei Gusaka (1)
An optical branching pattern with a +* degree is formed within the center, and seven branching paths with extremely small branching losses become the town.

Although the present invention has been described above as an actual example, since the present invention forms an optical waveguide within a substrate material, it is possible to use a material in which the atoms of the material are uniformly and tightly bonded. Therefore, transmission loss due to scattering, etc. within the waveguide I-tower is reduced.Also, since the optical waveguide is formed by etching, a waveguide pattern of any shape can be formed with high precision. Furthermore, according to the present invention, the cross section of the C waveguide, which undergoes ion exchange after etching, has the same refractive index distribution lag 1/-dated distribution, so that the round wires within the waveguide do not reach the surface. According to the present invention, the force H
By performing ion exchange on the etching acid to reduce the cost, the bending shape of the optical waveguide can be made to a sufficient value in the depth direction, and the branching pattern can also be made with precision. g can therefore be formed into a branch,
This becomes unnecessary when producing an optical plane circuit having a convergence or the like.

Furthermore, in the present invention, if a gradient index type 1/lens is formed when forming the waveguide at the end of the optical waveguide, light can be focused into a spot by this lens. Therefore, it is possible to reduce the cross-sectional shape of the optical waveguide, and the path can be downsized. By reducing the cross-sectional shape of the waveguide, the etching time can be shortened and the productivity of optical circuits can be significantly improved.

[Brief explanation of the drawing]

FIG. 1A is a perspective view of an optical plane circuit according to the first practical example of the present invention, FIG. 1B is an enlarged view of the same essential part, and FIG. 1C
is a graph showing the distribution of the condensing lens of this circuit,
Fig. 1D is a graph showing the Jifl refractive index distribution of the optical waveguide of this circuit, and Figs. i.?A is a diagonal diagram of a 1m optical circuit according to a modification of this practical example, and Figure 8A is a Y-view diagram of an optical plane circuit according to a practical example of the younger brother 2 of the present invention. 13 is a graph showing the /+11 refractive index distribution of one optical homowave flaw in this circuit.
・・・・・・・・・・・・・・・ Board (2)...
・・・・・・・・・−・・・・・・ 6 optical wave paths t3+
・・・・・・・・・・・・・・・・・・ JiQ gradient index lens (embedded lens) 18)・・・・・・・・・・・・
...... Td ion tl +) ...
・・・・・・・・・・・・・・・ a-S+ for etching
Mask 04)・・・・・・・・・・・・・・・ K
It is an ion. Agent Masaru Tsuchiya
Osamu Matsumura

Claims (1)

[Claims] 1. To increase the refractive index of the substrate! ion is diffused to form a high refractive index 1-, and then the high refractive index layer is etched into a desired shape such as a branching or converging pattern, and the Jlil refractive index is removed from the periphery of the tAfJ pattern. 1. A method of manufacturing an optical planar circuit, characterized in that 11 optical waveguides are constructed by diffusing ions that contribute to miniaturization. 2. Depending on the process of forming the optical waveguide, a rut (a refractive index gradient lens) of the optical waveguide is formed within the substrate. The manufacturing method of the round/to-plane circuit described in .