JPS5897028A - Optical waveguide switch - Google Patents

Abstract

PURPOSE:To obtain an optical waveguide switch which permits miniaturization and high scale integration, by providing a heating area in a part of an optical guide and controlling the part thereof electrically. CONSTITUTION:A thin film resistor 12 of a Y shape of NiCr or the like is provided on a branching circuit of an input waveguide 9 and output waveguides 10, 11 of an optical waveguide 2 on a dielectric substrate 1. When the resistor 12 is heated by applying voltage between the common power feed point A and selective power feed point B of said resistor and running electric current, the refractive index increases and the light propagating in the waveguie 9 propagates preferentially to the waveguide 10. Thus, the optical waveguide switch which permits miniaturization and large scale integration is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small optical waveguide switch that can electrically switch waveguides.

Optically transparent dielectric crystals, such as I, 1Nbo.

By heat-treating a sample with a waveguide shape on the surface of the crystal and a round part of 5 to 20 μm at about 10,000 ℃ for 5 to 7 hours, the metal T1 is diffused and the refractive index of that part becomes the same as that of the substrate LiNb.
0. Since the refractive index of the crystal increases by about 1)x%, an optical waveguide is formed.

Conventionally, optical waveguide switches have the following types: g1 (front view of al), Fig. 1 (bl (W, Fig. 1 (left side view of al), Fig. 1 (C3 (Ip!) right side impulse of Fig. 1 (a)). , Figure 1 (
As shown in the front view of dj, there is an example using the electro-optic effect of LiNbO5 crystal.

In this Figure III (aJ-Figure 1 (dl), l is a dielectric substrate made of LiNbO5 crystal, 2 is an optical waveguide, and as explained earlier, this optical waveguide 2 is a LiNbO5
Ti is deposited on the crystal, an I-lean is formed, and a diffusion layer is formed. t3 is a thin insulator such as 5ins, and an electrode 4 is formed on this insulator 3.

Electrodes 5°6, 7 on the optical waveguide 2 formed in this way
．． A voltage is applied to 8 to obtain an optical waveguide switch. By applying a voltage to the electrodes 5.6, the area sandwiched by the electrodes 5.6 is guided by the electro-optical effect.

Further, by applying a voltage to the electrodes 7 and 8, the input waveguide 90 is guided to the output waveguide Xi in the same manner as described above.

Since this type of optical waveguide relies on the linear electro-optic effect, a high voltage of 15 to 30 V is required, and it is difficult to obtain an extinction ratio of 15 dB or more for an unconnected waveguide.

Another object of the present invention is to provide an optical waveguide switch that can be used in an optical matrix.

Embodiments of the optical waveguide switch of the present invention will be described below with reference to the drawings. Figure 8142 (at is a plan view of one embodiment thereof, and Figure 2 (b) is
FIG. 3 is a cross-sectional view taken along line -a'. This second
In both Figures (&) and Figure 2 1b), l is a dielectric substrate, and the optical waveguide 2 on the dielectric substrate l is formed by a conventional method.

This invention is characterized in that a Kli thermal resistor 12 is formed on the optical waveguide forming branch circuit, and this heating resistor offering 2 has a butterfly and a dielectric substrate on which the optical waveguide 2 is shaped. A thin film resistor such as NlCr is placed on 121.
It is formed by performing YJ-shaped vapor deposition I4 turns.

The shape of the heating resistor 12 is such that the input waveguide 9 and the m- of the two output waveguides 10. The waveguide 9 is thinner than the output waveguide IQ11.

For example, by applying a voltage to the common line electrical point A1 selected and the selected electrical point B of the heating resistor 12, and causing a current to flow, 11. *1
Due to the temperature distribution dependence of the refractive index of LiNbO30, which is the base 411, when vertically heated to about 200C, the refractive index increases by about 1%.
A source layer V similar to that obtained by lower KTi diffusion of the H portion is formed.

Thus, the newly formed ex-guy? Effect and T
Due to the superimposition of the nine-element Guy-V effect, which is originally formed by l-diffusion, the element propagating through the input waveguide 9 preferentially propagates to the output waveguide 10.

Normally, the loss is large due to the curve between the selected feed points B and D, but in this invention, the one-party guide effect is large due to the effect of the heat generating resistor 12 in this region, and the loss is reduced and the cost is reduced. propagate.

As mentioned above, Ill! The first embodiment of the present invention shown in Figure 2 (false; 2nd WJ) is a book that allows easy realization of an optical waveguide switch with low p% loss and large extinction ratio by current drive at low voltage. It is.

FIG. 3 is a plan view of a second embodiment of the present invention, in which the input waveguide 90 is connected to the output waveguide 13.
14. Selective connection to the three output waveguides of 15 in common $
Between electric point A and selection 6 electric point E, common embroidery electric point A and selection wire electric point F
By energizing the heating resistor 12 between the common power supply point A and the selective power point G! It is something that is expressed.

Also, Fig. 4 (&) is a plan view showing the @30 embodiment of the output ψ of the cylinder.
FIG.

In the case of the example shown in Fig. 4 (bl),
In particular, it has a structure that increases the extinction ratio of the switch.

That is, in the fourth embodiment, there is a region where T1 diffusion is not partially performed on the lower side of the heating resistor 12, a tab, and a Ti
A non-diffusion area 16 is set.

In this state, if heat is generated between the common power point A, selective power point, and B of the heating resistor 12, the Kosha common power point A,
Selective electrical current is turned on and propagates in the B direction. On the other hand, in the output waveguide 11, the section between the common voltage point A and the selected value voltage point C is a light blocking region, so the source does not reach the output waveguide 11. You can make it bigger.

In this @3 embodiment, the light guide V by the heating resistor 12 is
It is extremely effective when the effect is sufficiently large.

In each of the above embodiments, LiN is used as the dielectric substrate l.
b0. Although an example using the above will be described, the present invention can achieve the same effect using a dielectric material that is optically transparent and has a positive temperature dependence of refractive index and can be used to construct a buried waveguide.

As described above, according to the optical waveguide switch of the present invention,
The optical waveguide switch was constructed by providing a heat generating area in a part of the optical waveguide and electrically controlling that part.
It does not require mechanical operation and can be used as an original switch, but it also has the advantages of being compact, highly integrated, and can be used in optical matrices.

[Brief explanation of the drawing]

Figure 11 (1) is a plan view of a conventional O optical waveguide switch, 51
Figure 31 (bl is li! I E (left side view of al, Figure 1 tel is right side view of Figure 1 (&), pJ1 figure (dl
4 is a front view of a conventional optical waveguide switch, FIG. 4 1al is a plan view of an embodiment of the optical waveguide switch of the present invention, and FIG. FIG. 3 is a cross-sectional view showing the second optical waveguide switch of the present invention.
FIG. 4 1al is a plan view showing an embodiment of the optical waveguide switch of the present invention. Plan view of the embodiment of No. 3, Ill! Figure 4 (bla Figure 4 (This is a cross-sectional view taken along the a-a' line of al. l... Dielectric substrate, 2... Optical waveguide, 9... Input waveguide. , IO, 11, 13-15... output waveguide,
12... Heat generating resistor, 16... T1 non-diffusion layer, A...
・Common power point, B-G-・Selection wire point. Patent applicant: Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] A dielectric substrate that is optically transparent and has a positive refractive index temperature dependence, and embedded in this dielectric substrate, one input waveguide and a plurality of output waveguides branched from the input waveguide and arranged at predetermined intervals. An optical waveguide, which is similar to a waveguide, is provided on the input waveguide and each output waveguide, and the input waveguide side is a common starting point, the output waveguide side is a selective point, and a common similar point. An optical waveguide switch comprising a linear heating resistor that selectively connects the input waveguide and the output waveguide by passing current between predetermined selective switching points.