JP3045857B2 - Optical waveguide deflector, guided light control method using the optical waveguide deflector, and optical waveguide device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide type deflector used for controlling the light flux width, condensing, reflection, etc. of guided light in an optical waveguide, a method for controlling a guided light by the optical waveguide type deflector, and an optical waveguide. It relates to a waveguide element.

[0002]

2. Description of the Related Art There has been proposed an optical integrated waveguide device in which a condenser and an optical input / output system are integrated with a thin film optical waveguide device. In recent years, with the miniaturization of the optical integrated waveguide device, the input light tends to be narrowed, and in order to converge the light well, it is necessary to increase the NA of the light condensing system. Since the pattern transfer mask used above is manufactured using a pattern generator, the drawing performance of the pattern generator, that is, the upper limit of the position and angle resolution limits the shape and size of the light collection system. From the above technical background, in order to realize good control of condensing guided light in a waveguide layer using narrow beam incidence, it is necessary to enlarge the incident light width in the waveguide layer. This is a suitable means for avoiding restrictions. In this case, in order to maintain the miniaturization of the device as an advantage of integration, it is desired to propose an optical path width conversion element with a simple configuration. An element having both optical path width control and light collection control may be useful in integration.

[0003]

Conventionally, an optical path width is converted in an optical waveguide by using an expander or a compressor formed by combining a plurality of curved surfaces (reflection surfaces and refraction surfaces) having positive and negative powers. In this case, a space for arranging a plurality of curved surfaces and accurate positioning are required, and it is difficult to reduce the size and simplification of the optical integrated waveguide device. In addition, as an optical waveguide reflection element, a reflection surface is formed on a slab waveguide with a gentle tapered structure that is non-parallel to the thickness direction of the waveguide layer, thereby realizing highly efficient reflection of guided light. ("Integrated optics and new wave phenom
enain optical waveguides ”PKTien, Reviews of Mod
ern Physics, Vol.49, No.2, April 1977, PP.378-37
9). However, this reflecting element has only a reflecting function.
It is necessary to combine with a curved surface having a negative power, and it is also difficult to miniaturize and simplify the optical integrated waveguide device.

The present invention has been made in view of the above circumstances, and is an optical waveguide type deflector capable of changing the light flux width of guided light propagating in an optical waveguide layer by using a reflecting portion having a simple structure. And a waveguide light control method and an optical waveguide element capable of simultaneously controlling deflection, collection (or divergence) and control of light beam width of guided light propagating in an optical waveguide layer by the optical waveguide deflector. Aim.

[0005]

To achieve the above object, an optical waveguide type deflector according to the present invention has a tapered surface whose end face provided at an end of a waveguide layer is non-perpendicular to the waveguide. The inclination (taper angle φ) of the tapered surface continuously changes in a direction parallel to the waveguide layer and perpendicular to the taper forming direction in the tapered surface. In the optical waveguide deflector according to the second aspect of the present invention, the end face provided at the end of the waveguide layer is a tapered surface having a curvature r that is non-perpendicular to the waveguide, and the inclination of the tapered surface (taper angle φ). Are continuously changed in a direction parallel to the waveguide layer and perpendicular to the taper forming direction in the tapered plane.

According to a third aspect of the present invention, there is provided the waveguide light control method using the optical waveguide type deflector according to the first aspect, wherein the inclination (taper angle φ) of the tapered surface provided at the end of the waveguide layer is controlled by the tapered surface. The waveguide light is incident on the tapered portion of the optical waveguide deflector continuously changing at a non-zero incident angle to control the deflection of the guided light and the beam width. According to a fourth aspect of the present invention, there is provided the waveguide light control method using the optical waveguide type deflector according to the second aspect, wherein the inclination (taper angle φ) of the tapered surface having a curvature provided at the end of the waveguide layer is reduced. In this method, guided light is made incident on a tapered portion of an optical waveguide deflector continuously changing in the inside, and condensing, deflecting, and a light beam width of the guided light are controlled. An optical waveguide device according to the invention of claim 5 is at least an optical waveguide deflector according to claim 1 or claim 2.
An optical waveguide type deflector as described above is provided.

[0007]

The optical waveguide deflector according to the first aspect is based on the principle of deflecting in the direction of propagation of the optical path in a layer having an equivalent refractive index distribution by a tapered structure. It also has the function of controlling the width of The optical waveguide type deflector according to claim 2 is based on the principle of deflection in the optical path propagation direction in a layer having an equivalent refractive index distribution due to a tapered structure, and thus has the advantage of high deflection efficiency and the width of a light beam. It also has a function of controlling, and further has a condensing (or diverging) action accompanying the reflection of the curved surface because the tapered surface is a curved surface.

According to the waveguide light control method of the third aspect,
The deflection of the guided light and the control of the light beam width can be simultaneously realized in a compact space. According to the guided light control method of the fourth aspect, it is possible to simultaneously realize the condensing (diverging), the deflection, and the light beam width control of the guided light in a compact space. According to the optical waveguide device of the fifth aspect, the deflection of the guided light and the control of the light beam width can be realized with a simple configuration, and the device can be miniaturized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a view showing an embodiment of the first aspect of the present invention, and is a three-dimensional schematic diagram of a shape of a reflecting portion of an optical waveguide deflector provided at an end of a waveguide layer. In FIG. 1, the shape of the reflecting portion is a tapered surface 1 having a continuously increasing taper ratio in the X-axis direction. That is, FIG.
And the inclination of the tapered surface 1 (taper angle φ) is φ ₁ >
It has become a φ _2. The operation of the reflector having the above configuration,
This is described below using the top view shown in FIG. First, in FIG. 2, a case where a guided light beam having a width d ₁ is incident on the reflecting portion (taper portion) at an incident angle θ will be described. In the comparison between the marginal rays L ₁ and L ₂ that define the incident light, the taper width at the incident position A ₁ of L ₁ is shorter than the taper width at the incident position A ₂ of L ₂ .

[0010] Here, the waveguide of light in the taper will be briefly described. The light incident on the tapered portion having a constant taper width as shown in FIG. 3A is affected by the equivalent refractive index distribution (see FIG. 3B) caused by the tapered structure, and is affected by the XY plane. While propagating in different directions. In addition, as shown in FIG. 4, the propagation state of the light in the side direction reaches the point B while gradually increasing the incident / reflection angle at the boundary surface from the point A in the taper structure, and the light traveling from the point B to the point C in the taper structure. The waveguide state is reversed from A → B. In this case, a Goos-Henschen shift occurs at the time of reflection at the boundary surface. Further, as the taper angle becomes smaller, the rate of change of the equivalent refractive index becomes smaller, so that the rate of change in the propagation direction of the incident light also becomes smaller, and the interval between the incident point A and the exit point C tends to increase. In the above-described propagation state in the lateral direction (YZ plane), reflection at the boundary surface depends on the total reflection condition. Therefore, the angle of the taper is required that the angle of incidence / reflection of the boundary surface at the point B is equal to or less than the total reflection angle. Radiated out of the layer.

Based on the above-described waveguide characteristics, a comparison of the optical path propagation of L ₁ and L ₂ in the tapered portion shown in FIGS. 1 and 2 reveals that the incident points A ₁ and A ₁ of L ₁ and L _2. Taper width at ₂
m ₁ and m ₂ satisfy m ₁ <m ₂ . Therefore, the equivalent refractive index distribution of the propagation light path in the tapered surface of the L ₁ is compared with the equivalent refractive index distribution of the propagation light path in the tapered surface of the L _2, since a large distribution rate of change, even the change in the propagation direction growing. Therefore, the emission light width | C ₁ −C ₂ | defined by the tapered surface emission points C ₁ and C ₂ of L ₁ and L ₂ is equal to the previously defined incident light width due to the propagation optical path difference. | A ₁ −A ₂ |. still,
The following is also clear from the above configuration principle. That is, in the embodiment shown in FIG. 5, the change in the inclination of the tapered surface 1 is reversed from that in FIG. 2, but in this case, it is necessary to reduce the luminous flux width of the emitted light with respect to the incident light. it can. Therefore, even in the reflecting portion having the same configuration, the light flux width can be reduced or increased by changing the change of the taper angle from small to large and large to small. Further, even with the same configuration of the tapered surface, the light beam width can be reduced or increased by reversing the incident direction and the exit direction. As described above, in the optical waveguide deflector of the first aspect, the reflection of the guided light and the control of the light beam width can be performed simultaneously with a simple configuration.

Next, a second embodiment will be described with reference to FIGS. FIG. 6 is a view showing one embodiment of the invention according to claim 2, and is a three-dimensional schematic view of the shape of the reflecting portion of the optical waveguide deflector provided at the end of the waveguide layer. In FIG. 6, the reflecting portion has a negative curvature in the concave direction, and X
The taper surface 1 has a taper ratio that is continuously reduced in the axial direction. That is, in FIG. 6, the tapered surface 1 has a curvature with a radius of curvature r, and the inclination (taper angle φ) of the tapered surface is φ ₁ <φ ₂ .

The operation of the reflecting section having the above configuration will be described below with reference to a top view shown in FIG. First, in FIG.
It describes the case where d ₁ becomes parallel light is incident on the reflecting portion (tapered portion). The marginal rays L ₁ ,
As for L ₂ , since the tapered surface 1 has a curvature as described above, the angles of incidence on the tapered surface 1 are θ ₁ , θ ₂
, It is clear that θ ₁ > θ ₂ . Looking further at the optical path propagation in the taper of the incident light beams L ₁ and L ₂ , the equivalent refractive index distribution in the L ₁ propagating optical path is smaller than the equivalent refractive index distribution in the L ₂ propagating optical path. Is small, the deviation between the incident point A (A ₁ , A ₂ ) and the exit point C (C ₁ , C ₂ ) is larger for L ₁ than for L ₂ (however, the taper ratio is constant) In the case of the above, the displacement amounts are equal). Therefore, the light flux is width d ₂ of the light flux is compressed than before while being converged. As described above, in the optical waveguide deflector of the second aspect, the reflection, collection, and control of the light beam width of the guided light can be simultaneously performed with a simple configuration. In the illustrated embodiment, the tapered surface 1 has a radius of curvature r.
However, other curved surfaces such as a paraboloid or a hyperboloid may be used. In addition, although the concave surface is seen from the waveguide layer 2 side, the emitted light (reflected light) can be divergent light if the convex surface is formed on the waveguide side.

Next, an embodiment of a guided light control method using an optical waveguide deflector according to the third aspect will be described. In the optical waveguide deflector shown in FIGS. 1 and 2, the tapered surface abcd has a continuous taper angle φ in the X-axis direction in FIG. At this time, since the equivalent refractive index in the tapered portion decreases as the film thickness decreases, a continuous decrease in the refractive index in the -Y direction in the figure is given, and the equivalent refractive index in the + X direction in the figure is given. With a decrease in rate of change. Therefore, by providing the above configuration, it is possible to obtain an optical waveguide type deflecting means having different deflecting effects depending on the incident position of the light beam. That is, in FIG. 2, the taper length in the tapered portion incident point A ₂ of the marginal ray L ₂ of the + X side of the incident light beam is tapered in the tapered portion incident point A ₁ of the -X side marginal ray L ₁ of the same incident light beam Longer than the length, the equivalent refractive index changes slowly, and in the optical path propagation in the tapered portion, the L ₂
The results of comparison with the L _1, deflection action takes place slowly,
The amount of deviation of the exit point of the tapered portion from the incident point is L ₂
It is larger than that of the L ₁ of. That is, the width of the emitted light beam is extended. In the same configuration, if the direction of the incident light beam is reversed, the width of the emitted light beam is compressed. As described above, by using the optical waveguide deflector having the configuration shown in FIGS. 1 and 2 and adjusting the incident direction, the incident position, and the incident angle of the guided light, the deflection of the guided light and the beam width can be easily controlled. can do.

Next, an embodiment of a guided light control method using an optical waveguide deflector according to claim 4 will be described below. In the optical waveguide type deflector shown in FIGS. 6 and 7, the tapered surface abcd has a curvature and has a continuous increase in the taper angle φ in the + X axis direction in FIG. At this time, since the equivalent refractive index in the tapered portion decreases as the film thickness decreases, it has a continuous decrease in the refractive index in the -Y direction in the figure, and also has the equivalent refractive index in the + X direction in the figure. With an increase in the rate of change. Accordingly, the light incident on the tapered surface 1 having the above-described features is collected with the difference in the incident angle due to the above-mentioned curvature, and the emitted light flux is obtained from the gradual difference in the equivalent refractive index distribution in the optical path propagation in the tapered portion. The width is compressed against the incident beam width. In the same configuration, if the direction of the incident light beam is reversed, the output light beam width is expanded as compared with the incident light beam width, and the light beam becomes divergent light. As described above, by using the optical waveguide deflector having the configuration shown in FIGS. 6 and 7 and adjusting the incident direction, the incident position, and the incident angle of the guided light, the deflection, collection (divergence), and The light beam width can be easily controlled.

Next, an embodiment of the optical waveguide device according to the fifth aspect will be described. The optical waveguide device according to claim 5,
2. The optical waveguide deflector according to claim 1, shown in FIGS.
Alternatively, an optical waveguide deflector according to claim 2 shown in FIGS. 6 and 7 is provided to simplify the element configuration. Here, as a conventional example, FIG. 8 shows an example of an optical waveguide element. In FIG. 8, in order to expand a light flux of guided light coupled to a core of the optical waveguide by a coupler / prism, a conventional positive An expander consisting of a reflector (a) having a curvature and a reflector (b) having a negative curvature was arranged. On the other hand, according to the present invention, if the optical waveguide is provided with the optical waveguide type deflector (c) having the configuration shown in FIGS. 1 and 2 as in the embodiment shown in FIG. (Extension) can be realized. As described above, in the optical waveguide device according to the fifth aspect, the deflection of the guided light and the control of the luminous flux width can be realized with a smaller device configuration than the conventional one, and the device can be downsized.

[0017]

As described above with reference to the illustrated embodiment, the optical waveguide type deflector according to the first aspect deflects in the optical path propagation direction in a layer having an equivalent refractive index distribution by a tapered structure. Therefore, in addition to the advantage that the deflection efficiency is high, it also has a function of controlling the width of the light beam. As a result, the size and simplification of the device can be achieved as compared with the conventional light beam width control method using an expander or a compressor having a plurality of curved surfaces having positive and negative powers. The optical waveguide type deflector according to claim 2 is based on the principle of deflection in the optical path propagation direction in the waveguide layer having an equivalent refractive index distribution by a tapered structure, and therefore has the advantage of high deflection efficiency and low reflection loss. In addition, since the tapered surface is a curved surface, it has a function of condensing (or diverging) due to the reflection of the curved surface, and also has a function of controlling the emission light beam width using the difference in the propagation optical path length in the tapered structure due to the difference in the taper ratio. Therefore, the same control can be performed with a simpler configuration than in the past, which is useful in integrating and miniaturizing elements.

According to the waveguide light control method of the third aspect,
The deflection of the guided light and the control of the light beam width can be simultaneously realized in a compact space, thereby improving the degree of integration of the optical integrated device. According to the waveguide light control method of the fourth aspect, it is possible to simultaneously control (diverge), deflect, and luminous flux the guided light in a compact space, thereby improving the degree of integration of the optical integrated device. According to the optical waveguide device of the fifth aspect, the deflection of the guided light and the control of the light beam width can be realized with a more compact space and a simple configuration than before.
The element can be reduced in size. Therefore, with the same size as before,
A more sophisticated device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of the invention described in claim 1, and is a three-dimensional schematic view of a reflecting portion (tapered portion) of an optical waveguide deflector provided at an end of a waveguide layer.

FIG. 2 is a top view of the reflecting portion (tapered portion) shown in FIG. 1 as viewed from a Z direction.

FIG. 3A is a top view of a reflecting portion (tapered portion) when a taper width is constant, and FIG. 3B is a diagram showing an equivalent refractive index distribution of the tapered portion.

FIG. 4 is a side view of the reflection section (tapered section) of FIG. 3A when viewed from the X direction, and is a diagram showing a propagation state of guided light in the side direction.

FIG. 5 is a top view of the reflection portion (taper portion) when the change in the inclination of the tapered surface is reversed from that in FIG.

FIG. 6 is a view showing an embodiment of the invention described in claim 2, and is a three-dimensional schematic view of a reflecting portion (tapered portion) of an optical waveguide deflector provided at an end of a waveguide layer.

FIG. 7 is a top view of the reflecting portion (tapered portion) shown in FIG. 6 as viewed from the Z direction.

FIG. 8 is a diagram showing an example of a conventional optical waveguide element,
(A) is a plan view, (b) is a side sectional view.

FIG. 9 is a plan view of an optical waveguide device showing an embodiment of the invention described in claim 5;

[Explanation of symbols]

 1 tapered surface 2 waveguide layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 6/12-6/138

Claims (5)

(57) [Claims] 1. An end face provided at an end of a waveguide layer is a tapered surface which is non-perpendicular to the waveguide, and the inclination (taper angle φ) of the tapered surface is equal to the thickness of the waveguide layer within the tapered surface. An optical waveguide deflector characterized by being continuously changed in a direction parallel to and perpendicular to a taper forming direction. 2. An end face provided at an end of a waveguide layer is a tapered face having a curvature r which is non-perpendicular to the waveguide, and the inclination (taper angle φ) of the tapered face is such that the guide is formed within the tapered face. An optical waveguide type deflector characterized by being continuously changed in a direction parallel to a waveguide layer and perpendicular to a taper forming direction. 3. The method for controlling guided light by an optical waveguide deflector according to claim 1, wherein the inclination (taper angle φ) of the tapered surface provided at the end of the waveguide layer is continuously within the tapered surface. To the tapered part of the optical waveguide deflector that changes
A guided light control method using an optical waveguide deflector, wherein guided light is incident at a non-zero incident angle, and deflection and luminous flux width of the guided light are controlled. 4. The method of controlling guided light by an optical waveguide deflector according to claim 2, wherein the inclination (taper angle φ) of the tapered surface having a curvature provided at the end of the waveguide layer is within the tapered surface. A waveguide light control method using an optical waveguide type deflector, wherein a waveguide light is made incident on a tapered portion of an optical waveguide type deflector which is continuously changed, and condensing, deflection and light beam width of the waveguide light are controlled. . 5. An optical waveguide device comprising at least the optical waveguide deflector according to claim 1 or the optical waveguide deflector according to claim 2.