JPH1114916A - Waveguide type optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switch capable of performing highly reliable switching with a small driving force by providing a projection on the substrate side surface of a moving flat optical waveguide. SOLUTION: A separation layer 2 located below cantilever beams 6 and 7 and a connecting member 8 is eliminated by etching, and the surface of substrate 1 is exposed around the cantilever beams 6 and 7 and the connecting member 8. A recess 24 is formed on the full surface of the separation layer 2. In the lower surface of the cantilever beams 6 and 7 and the connecting member 8, a projection is formed in a position corresponding to the recess 24. Friction forces between the cantilever beams 6 and 7 and the connecting member and the substrate are reduced, and adhesion is also suppressed. Thus, even if forces generated by electromagnetic actuators 11a and 11b are small, opticalswitching is performed. Further, since there is no difference in the friction reducing effect even if a gap between the projection formed in the lower surface of the cantilever beams 6 and 7 and the connecting member 8 and the substrate is small, sure optical-switching is performed while changes in the attitudes of the cantilever beams 6 and 7 and the connecting member 8 are maintained small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical switch used in a new field of optical communication, and more particularly to a small-sized waveguide type optical switch suitable for remote operation.

[0002]

2. Description of the Related Art As a conventional optical waveguide switch, there is an optical switch disclosed in Japanese Patent Application Laid-Open No. 6-148536.
This switch is a 1 × 2 optical switch that switches an optical path by forming a cantilever on a silicon substrate and moving an optical waveguide formed thereon using electrostatic force.

[0003]

The above-mentioned conventional optical switch has the following problems. That is,
Since both portions of the cantilever formed on the silicon substrate and the substrate are in contact with each other, both portions are flat. Therefore, friction between the two portions is large, and it is difficult to move the cantilever. In addition, the cantilever and the substrate sometimes adhere to each other due to the adhesion phenomenon. This problem can be solved by increasing the distance between the substrate and the cantilever, but the cantilever falls into the space between the substrate and the cantilever, which significantly reduces optical coupling efficiency and increases insertion loss. Problem had arisen.

An object of the present invention is to solve such a problem, and it is an object of the present invention to realize an optical switch capable of performing highly reliable optical switching with a small driving force.

[0005]

In order to achieve the above-mentioned object, an optical waveguide switch according to the present invention has a projection on a substrate side surface of an optical waveguide. This can prevent the substrate and the optical waveguide from coming into contact with each other on a plane, so that the frictional resistance when the optical waveguide moves can be reduced. Further, since the contact area is small, it is possible to prevent the substrate and the optical waveguide from sticking to each other. Also, by reducing the distance between the tip of the protrusion and the substrate, it is possible to suppress a decrease in optical coupling efficiency due to the cantilever falling into the space between the substrate and the cantilever.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view including a partial cross section of a waveguide type optical switch according to the present invention.

1 is a substrate, 2 is a separation layer made of silicon,
3 is a quartz glass layer, 4 and 5 are input side optical waveguide cores, 6
And 7 are cantilever beams, 8 is a connecting member, 9a, 9b, 10a
10b are output side optical waveguide cores, 11a and 11b are electromagnetic actuators, 12a and 12b are actuator electrodes, 13 is a cover, 14 is a soft magnetic material, and 24 is a depression. However, only the attachment positions of the cover 13 and the soft magnetic body 14 are indicated by broken lines for convenience.

Light input to the input side optical waveguide core 4 formed on the quartz glass layer 3 passes on the cantilever 6. The cantilever 6 is attracted to one side by the magnetic attraction between the electromagnetic actuators 11a and 11b and the soft magnetic body 14, and the input side optical waveguide core 4 becomes the output side optical waveguide core 9a or 9b.
To join. The electromagnetic actuators 11a and 11b are supplied with power from a power source (not shown) through the electrodes 12a and 12b. Electromagnetic actuators 11a and 11b
The light can be switched by reversing the action of. The light input to the input side optical waveguide core 5 is similarly coupled to the output side optical waveguide core 10a or 10b.

Since the separation layer 2 below the cantilever beams 6 and 7 and the connecting member 8 is removed by etching, the surface of the substrate 1 is exposed around the cantilever beams 6 and 7 and the connecting member 8. . A depression 24 is formed on one surface of the separation layer 2. Projections are formed on the lower surfaces of the cantilever beams 6, 7 and the connecting member 8 at positions corresponding to the depressions 24,
The frictional force between the cantilever beams 6, 7 and the connecting member 8 and the substrate is reduced, and adhesion is also suppressed. As a result, light can be switched even if the force generated by the electromagnetic actuators 11a and 11b is small.

The effect of reducing the frictional force does not change even if the gap between the tip of the protrusion formed on the lower surface of the cantilever beams 6 and 7 and the connecting member 8 and the substrate is reduced, so that the cantilever beams 6 and 7 and the Light switching can be reliably performed while suppressing a change in the posture of the connecting member 8 to be small. Further, by using the cover 13, it is possible to prevent the cantilever beams 6, 7 and the connecting member 8 from deviating from normal positions due to disturbance.

In FIG. 1, only silicon is used as the separation layer. However, similar results can be obtained by using a separation layer made of silicon, titanium, platinum or a combination thereof.

FIG. 2 is a perspective view when only the cantilever is taken out and viewed from the substrate side.

Reference numeral 25 denotes a projection.

A projection 25 is formed on one surface of the cantilever beams 6, 7 and the connecting member 8 on the substrate side. This limits the contact area with the substrate to a small one,
Resistance due to friction when the 7 and the connecting member 8 move is reduced, and adhesion is also suppressed.

FIG. 3 is a sectional view of a lower portion of a soft magnetic body in a conventional switch.

Reference numeral 15 denotes a refractive index matching liquid, and reference numeral 16 denotes a path through which the refractive index matching liquid flows with a switch operation.

In the conventional switch, the refractive index matching liquid 15 flows along the path 16 as the switch operates. That is, the refractive index matching liquid 15 includes the cantilever beams 6 and 7 and the connecting member 8.
It is necessary to pass through a narrow gap between the liquid crystal and the substrate 1, and the resistance of the flow of the refractive index matching liquid 15 due to this causes an increase in the switching time.

FIG. 4 is a sectional view showing an AA 'section in FIG. 1 of the optical switch according to the present invention.

Reference numeral 17 denotes a refractive index matching liquid 1 accompanying a switch operation.
Reference numeral 5 indicates a path.

The projections 25 are formed on the substrate-side surfaces of the cantilever beams 6 and 7 and the connecting member 8. The refractive index matching liquid 15 flows between the projections 25 and flows like the path 17 in addition to the path 16. be able to. Since the height of the path 17 is higher than that of the path 16 by the height of the protrusion 25, the resistance when the refractive index matching liquid 15 flows is made smaller than that of the path 16 by making the height of the protrusion 25 sufficiently large. Can be.

FIG. 5 is a diagram schematically showing a manufacturing process of the optical switch according to the present invention.

Reference numeral 18 denotes a hole, 19 denotes a second separation layer, 20 denotes a hole, 21 denotes an etchant for the separation layer, 22 denotes a gap between the projection and the substrate, and 23 denotes a gap between the beam and the substrate in a portion without the projection. 26 is a waveguide core.

First, a quartz substrate 1 shown in FIG.
2 (b), a separation layer 2 made of silicon and having a thickness of 2 microns is formed. The separation layer 2 may be formed by a film formation method such as a sputtering method, a vapor deposition method, a chemical vapor deposition method (CVD method) or an ion beam film formation method, or a previously prepared silicon plate is bonded to the substrate 1. A method may be used.

Next, a hole 18 penetrating to the substrate 1 is formed in the separation layer 2 by etching in FIG.

Next, in FIG. 2D, a separation layer 19 made of silicon and having a thickness of 0.5 μm is formed. The separation layer 19 is formed by a sputtering method, a vapor deposition method, a chemical vapor deposition method (CVD).
Method) or a film forming method such as an ion beam film forming method.

Next, a quartz glass layer 3 and a waveguide core 26 are formed as shown in FIG.

Next, in FIG. 2F, the through-hole 2 reaching the separation layer 19 in the quartz glass layer 3 along the outer shape of the cantilever 6.
0 is formed by etching. As the etching method, wet etching and dry etching can be applied. In this embodiment, dry etching having anisotropy in the etching direction is used.

Next, the separation layers 2 and 19 are etched as shown in FIG. As the etching method, wet etching and dry etching can be applied. In this embodiment, wet etching using the silicon etching liquid 21 is performed. FIG. 9G shows a state where the etching has progressed halfway.

FIG. 3H shows the state after the completion of the etching. The separation layers 2 and 19 below the cantilever 6 are etched away, so that the cantilever 6 can move separately from the substrate 1. A projection 25 is formed on the lower surface of the cantilever 6, and a gap 22 is formed between the projection 25 and the substrate 1. In the case of the present embodiment, the size of the gap 22 is equal to 0.5 μm of the thickness of the separation layer 19. The gap 23 between the beam and the substrate in the portion without the protrusion is wider than the gap 22 and is equal to the total thickness of the separation layers 2 and 19 of 2.5 μm. As a result, the contact area with the substrate is limited to be small, the resistance due to friction when the cantilever 6 moves is reduced, and adhesion is also suppressed.

In this embodiment, the separation layers 2 and 19 made of silicon are formed on the substrate 1. However, the cantilever 3 can be similarly formed by using a separation layer made of titanium, platinum, or a combination thereof instead of silicon. It can be separated from the substrate 1.
Further, in this embodiment, the thickness of the separation layer 19 is set to 0.5 μm. However, if the thickness is less than the height of the waveguide core 4, the cantilever 6 falls into the space where the separation layers 2 and 19 are removed. Optical coupling is not lost.

In this embodiment, the separation layers 2 and 19 are finally completely removed. However, if the cantilever 6 is separated from the substrate 1, the separation layers 2 and 19 are partially left. Is also good.

[0033]

According to the present invention, it is possible to drive with a small force,
It is possible to realize a low-cost optical switch with small insertion loss.

[Brief description of the drawings]

FIG. 1 is a perspective view partially showing a cross section of an embodiment of a waveguide type two-circuit 1 × 2 optical switch according to the present invention.

FIG. 2 is a perspective view when only the cantilever is taken out and viewed from the substrate side.

FIG. 3 is a sectional view of a lower portion of a soft magnetic body in a conventional switch.

FIG. 4 is a diagram illustrating an optical switch according to the present invention in FIG.
Sectional drawing which shows A 'section.

FIG. 5 is a diagram schematically showing a manufacturing process of the optical switch according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Separation layer made of silicon, 3 ... Quartz glass layer, 4 and 5 ... Input side optical waveguide core, 6 and 7 ... Cantilever, 8 ... Connecting member, 9a, 9b, 10a and 10b ...
Output side optical waveguide cores, 11a and 11b: electromagnetic actuators, 12a and 12b: actuator electrodes, 13
... cover, 14 ... soft magnetic material, 15 ... refractive index matching liquid, 16
... the path through which the refractive index matching liquid flows with the switch operation, 17
... the path through which the refractive index matching liquid 15 flows with the switch operation
18, 20: Hole, 19: Separation layer, 21: Separation layer etchant, 22: Gap between projection and substrate, 23: Gap between beam and substrate in portion without projection, 24: Recess, 25: Protrusion,
26 ... waveguide core.

Continued on the front page (72) Inventor Masaru Muranishi 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref., Machinery Research Laboratories, Hitachi, Ltd. (72) Inventor Rebun Komatsu 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Information and Communication Division, Hitachi, Ltd. (72) Inventor Hiroaki Okano 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable, Ltd. Opto-System Research Laboratory (72) Inventor Dai Kobayashi 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Pref.

Claims (1)

[Claims] In an optical switch for switching an optical path of an input optical signal by mechanically moving a planar optical waveguide on a substrate, a projection is provided on a surface of the movable planar optical waveguide on a substrate side. Waveguide type optical switch.