JPS6138937A - Photoelectric converter formed on substrate - Google Patents

Abstract

PURPOSE:To attain highly efficient photoelectric conversion by forming a photovoltaic element on a surface obliquely crossed in the depth direction of an optical waveguide. CONSTITUTION:The surface obliquely crossed in the depth direction is formed on the optical waveguide 11 of a substrate 10 and the photovoltaic element 15 is formed so as to cover said surface. In said constitution, light transmitted through the waveguide 11 is made incident on the element 15 directly from an oblique part, so that highly efficient photoelectric conversion can be attained.

Description

BACKGROUND OF THE INVENTION The present invention relates to a photoelectric conversion device formed on a substrate, and is particularly useful for optical logic circuits integrated on a substrate.
It is concerned with a device for generating electromotive force from Hikari No. 11.

In recent years, optoelectronic technology has made remarkable progress, and the realization of optical ICs has been raised as one of the development issues. In fact, the basic logic circuits of optical ICs, such as optical logic (
OR> circuits and optical exclusive OR circuits have been proposed. The applicant has also proposed various optical logic circuits integrated on M boards (for example, Japanese Patent Application No. 59-1)
17552-117554 etc.). In these optical logic circuits, an optical signal is converted into an electrical quantity, and various types of light control are achieved using this electrical quantity by utilizing the electro-optic effect of the substrate.

A sufficient amount of electricity, such as a sufficiently high voltage, is required to achieve the desired light control.

Summary of the Invention The present invention provides a photoelectric conversion device that efficiently utilizes light propagating through an optical waveguide formed on a substrate to obtain a sufficient amount of electricity necessary for operating an optical logic circuit or the like. This is what we provide.

The photoelectric conversion device according to the present invention is formed so that the optical waveguide formed on the substrate is diagonally crossed in the depth direction, and the photovoltaic element is formed so as to cover at least this inclined surface. Characteristics/characteristics. A certain portion of the light propagating through the optical waveguide directly enters the photovoltaic element from this inclined surface and is used to generate electromotive force, achieving highly efficient charging conversion.

DESCRIPTION OF EMBODIMENTS An embodiment in which a photoelectric conversion device according to the present invention is applied to an optical NOT circuit, which is a basic element of an optical logic circuit, will be described in detail below. ``First, let me explain the optical NOT logic.

Optical NOT logic is the same as electrical signal NOT logic.

In FIG. 1, the input optical signal is represented by 11n. The output optical signal output as a result of the optical NOT logical operation on this input optical signal is indicated by 1out. The light line represents the logical value rlJ, and the light heat represents the logical value rOJ.

When the input optical signal fin is rOJ, the output optical signal ■011
t is "1", and if the input is "1", the output is "0"
becomes.

In FIG. 2, the substrate (10) is liNbo3.
A crystal is used, and three optical waveguides (11), (12) and (13) are formed on this substrate (10). These optical waveguides are created by, for example, depositing or sputtering Ti on the entire surface of the substrate (10), using this Ti film to form a waveguide pattern of Ti by a lift-off method, and then roughly exposing the Ti in an oxygen atmosphere. 970 in
This is done by thermal diffusion into the substrate (10) for 5 hours at .degree.

The first optical waveguide (11) is formed from one end of the substrate (10) to near the center of the substrate (10) or to the other end of the substrate (10>), and is located at the terminal end or halfway of the optical waveguide (11). A photovoltaic device (15) is fabricated.The photovoltaic device (15) is preferably made of CdTe, for example.The photovoltaic cord (15) is shown enlarged in FIG. As shown in FIG.
Spin the resist 1-, expose it to light using a vol-mask, and develop the resist 1-, forming a window of the resist 1- on the optical waveguide (11) and, if necessary, around it. .

Then, etching is performed in a heated solution of (HF + 1-1N Oa). This etching forms a depression on the optical waveguide (11). CdT in this depression
A photovoltaic device is produced by depositing CdTe and forming terminals at appropriate locations (for example, on both sides of the top surface of CdTe).

FIG. 3(B) shows the optical power incident on the photovoltaic element (15) out of the light propagating within the optical waveguide (11), with distance in the traveling direction of the light being plotted on the horizontal axis. Photovoltaic element (
The power of the light propagating through the optical waveguide (11) at the position before the optical waveguide (15) is assumed to be 1. As can be seen from this graph, much light is transmitted to the photovoltaic element (
15), and a portion of the propagating light also enters the photovoltaic element (15) in the portion where the depth of the optical waveguide (11) located at the bottom of the recess is reduced.

The light that does not enter the photovoltaic element (15) passes through the optical waveguide (
11> is further propagated and used for other purposes, or if there is no other use, it becomes a photovoltaic element (15)
The position is defined as the termination of the optical waveguide (11). In this case, a portion of the light reflected at the end of the optical waveguide (11) will also enter the photovoltaic element (15).

In FIG. 2, the second optical waveguide (12) is connected to the substrate (10
) is formed from the -gasm to the other end.

One end of the third optical waveguide (13) is close to a part of the second optical waveguide (12), and
is away from the optical waveguide (12).

Portions of the second optical waveguide (12) and the third optical waveguide (13) that are close to each other constitute a directional coupler. A pair of electrodes (14) are provided on the optical waveguide portion constituting this directional coupler.A photovoltaic element (15) is connected to this electrode (14) by a wiring pattern (16). Both terminals are connected, and the electromotive force of the element (15) is applied to the electrode (14).
) is applied. The electrode (14), the wiring pattern (16), and the terminal of the photovoltaic element (15) are fabricated by refining AI into a predetermined pattern.

A directional coupler causes optical power to be exchanged between two parallel optical waveguides that are close to each other. Optical waveguide (1
A directional coupler constituted by parts 2) and (13) that are close to each other is configured such that 100% of the power of the light propagating through one optical waveguide (12) is transferred to the other optical waveguide (13). The interaction length, coupling coefficient, phase constant, etc. are set in .

Since LiNbO3 is a crystal with an electro-optic effect, when an electric field is applied to this crystal, its refractive index changes. When a voltage generated from the photovoltaic element (15) is applied to the electrode (14), the refractive index of the optical waveguide (12) (13) changes, causing the optical waveguide (12) (13) to
) changes the phase constant in these parts of the optical waveguide (12) (in the case of Z-cut LiNbO3)
By changing the refractive index between these optical waveguide parts in (13), the strength of the i, - combination changes (in the case of Y cut [-!NEIO3). Due to changes in coupling strength and phase matching, optical waveguides (12) (13>
In a directional coupler composed of adjacent portions, no optical power shift occurs.

Now, the operation of the optical NOT circuit shown in FIG. 2 will be explained in a unified manner. The input optical signal ■In is the first optical waveguide (11)
will be introduced in The second optical waveguide (12) includes a reference light 1
inR is always input.

The output optical signal (Out) is obtained from the third optical waveguide (13).

When the input optical signal 1 inch is "○", the photovoltaic element (
Since no electromotive force is generated from 15), no voltage is applied to the electrode (14). Therefore, 100% of the light propagating through the optical waveguide (12) is transferred from the directional coupler to the leading waveguide (13), and the output optical signal (out becomes "1").

When the input optical signal (in is “1”, the optical waveguide (11
) generates a voltage in the photovoltaic element (15), which is applied to the electrode (14). Therefore, the light propagating through the optical waveguide (12) does not transfer from the directional coupler to the optical waveguide (13).
We will continue to spread the word.

Therefore, the output optical signal 1out becomes "O".

In the above explanation, the amount of optical power transfer in the directional coupler is ideally 100%, but of course it is 100%.
It does not need to be 0%. This is because it is sufficient to level-discriminate the power of the optical signal 01lt output from the optical waveguide (13) to determine the logical values ``1j'' and ``O''.

FIG. 4 shows a modification. Here, the optical waveguide (1
A hemispherical depression is formed by polishing in the middle or on the end of step 1), and CdTe is deposited on the inner surface of this depression. In this case as well, much light enters the photovoltaic element (15) from the curved surface of the recess that is oblique in the depth direction of the optical waveguide (11).

FIG. 5 further shows an example of the problem. Here, a large depression is formed over the entire depth of the optical waveguide (11), so that the optical waveguide (11) has an inclined surface over the entire depth direction. It has been cut by.

CdTe is deposited on this end inclined surface to form a photovoltaic element (15). In this example, the optical waveguide (11
), almost all of the light that has propagated through the photovoltaic element (
15) and is used.

In any case, the photovoltaic element (15) is an optical waveguide (15).
1) is formed on an inclined surface that crosses the optical waveguide (11) in its depth direction, so much of the light propagated through the optical waveguide (11) is input to the photovoltaic element and used. Therefore, a highly efficient and large electromotive saw can be obtained, and can be applied to control of optical signals using the electro-optic effect as described above.

It goes without saying that the optical logic circuit to which this invention is applied is not limited to the above-mentioned optical NOT circuit, and the invention can be applied to elements formed on a substrate other than optical logic circuits. Photovoltaic elements are not limited to CdTe, but also plasma CVD
Various materials such as a-8i produced by the method can be used.

[Brief explanation of the drawing]

Fig. 1 is a waveform diagram showing an optical NOT logical operation, Fig. 2 is a perspective view showing an embodiment in which the present invention is applied to an optical NOT circuit, and Fig. 3 (A) is a waveform diagram showing an optical NOT logic operation. 3(B) is a graph showing the optical power incident on the photovoltaic element, FIG. 4 and FIG. 5 are modified examples, and (A) is the second A cross-sectional view corresponding to an enlarged cross-section taken along the line ■-■ in the figure, and (B) a graph showing the optical power incident on the photovoltaic element. (10)...Substrate, (11) (12> (13)
)... Optical waveguide, (15)... Photovoltaic element. Applicant for the above patents: n6 Denki Co., Ltd. Engraving of the drawing in Figure 1 (no change in content) Figure 3 (A) CB) Inscription of drawing 8 (no change in content @Figure 4 [Jiro on page 71 (change in content) None) Article 5N (A) Procedural Amendment Form C) December 1, 1982? Mr. Manabu Shiga, Commissioner of the Japan Patent Office, 3. Relationship with the Oton Case to be amended Special 1. 'Applicant: 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto City Name (294) Tateishi Electric Co., Ltd. 4, Agent Å

Claims (1)

[Claims] A photoelectric conversion device formed on a substrate, in which a surface is formed that diagonally crosses an optical waveguide formed on the substrate in the depth direction thereof, and a photovoltaic element is formed so as to cover at least this inclined surface.