JPH04263214A - Semiconductor optical waveguide controller - Google Patents

Abstract

PURPOSE:To obtain the optical waveguide semiconductor controller which consumes less electric power and allows high-speed operations without etching the semiconductor layers with the semiconductor optical waveguide controller which forms an optical waveguide by controlling the optical waveguide characteristics of the semiconductor. CONSTITUTION:The multiple quantum well semiconductor layer 3 alternately laminated with the two semiconductor layers varying in band gap energy is held by the 1st semiconductor layer 1 and the 2nd semiconductor layer 2 to form double hetero-junctions. Two band-shaped upper electrodes 41, 42 are formed apart a spacing 44 atop the 1st semiconductor layer 1. Two band-shaped lower electrodes 51, 52 are formed apart a spacing 54 on the rear surface of the 2nd semiconductor layer 2. A voltage source 7 is connected to the upper electrodes 41, 42 and the lower electrodes 51, 52 to constitute the controller in such a manner that electric fields are impressed to the multiple quantum well semiconductor layer 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor optical waveguide control device for forming an optical waveguide by controlling the optical waveguide characteristics of a semiconductor. As in the case of integrated circuits in which ordinary semiconductor elements are integrated, the performance of optical devices can be improved by forming optical integrated circuits in which optical elements are integrated on a chip. When forming an optical integrated circuit, it is necessary to form an optical waveguide, which is an optical wiring corresponding to the metal wiring in a normal integrated circuit. An optical waveguide in an optical integrated circuit must be easily formed without processing a semiconductor layer, and must also be easily integrated with an optical element such as a laser or a light-receiving element.

0002

2. Description of the Related Art A conventional method for forming an optical waveguide in an optical integrated circuit will be explained with reference to FIG. Figure (a) is a cross-sectional view of an optical integrated circuit, figure (b) is a graph showing the refractive index distribution along the line X-X', and figure (c) is a graph showing the refractive index distribution along the line Y-Y'. It is a graph showing distribution. In this optical integrated circuit, as shown in FIG. 22(a), a double heterojunction is formed between a semiconductor layer 301 and a semiconductor layer 302 with a different type of semiconductor layer 303 sandwiched therebetween. semiconductor layer 3
A band-shaped convex portion 306 having a width a is formed on the upper surface of the semiconductor layer 301 in order to form an optical waveguide in the semiconductor layer 301 . When the convex portion 306 is formed in the semiconductor layer 301, the structure shown in FIG.
), the refractive index of the central portion 308 directly below the convex portion 306 of the semiconductor layer 301 is greater than the refractive index of the surrounding portions. Since light is confined in a portion with a high refractive index, an optical waveguide with a width a and a thickness b is formed directly under the convex portion 306 of the semiconductor layer 303.

However, in the conventional method shown in FIG. 22, the belt-shaped protrusions 306 are formed by etching the thickly formed semiconductor layer 301, which causes the following problems. Since the semiconductor layer 301 has a crystal orientation, if the direction of the optical waveguide differs from the crystal orientation of the semiconductor layer 301, the cross-sectional shape of the convex portion 306 will differ. That is, as shown in the plan view of FIG. 23(a), when a bent convex portion 306 is formed on the semiconductor layer 301, A
In the direction of -A' line, as shown in FIG. 23(b), there is a tapered convex portion 306 that is narrow at the top and wide at the bottom;
In the direction of the line ', as shown in FIG. 23(c), the convex portion 306 has a reverse tapered shape and is wide on the upper side and narrow on the lower side. For this reason,
There is a problem in that the width and shape of the optical waveguide differ depending on the direction of the optical waveguide, and the loss in the optical waveguide becomes large.

Furthermore, the etched surface of the semiconductor layer 301 has fine irregularities and is more chemically active than the unetched surface. Therefore, there is a problem in that the etched surface is prone to oxidation and the like, which may cause a decrease in the reliability of the optical integrated circuit. Figure 22(a)
As shown in FIG. 2, when the etched surface of the semiconductor layer 301 and the semiconductor layer 303 constituting the optical waveguide are close to each other, there is a problem in that the etched surface is particularly susceptible to the effects of the chemically active etched surface.

In order to solve these problems, the inventor of the present invention has proposed a method of forming an optical waveguide without etching the semiconductor layer. The proposed method will be explained using FIG. 24. Figure (a) is a cross-sectional view of an optical integrated circuit, Figure (b) is a graph showing the current density distribution along the line X-X', and Figure (c) is a graph showing the refractive index along the line X-X'. It is a graph showing distribution.

In this optical integrated circuit, FIG. 24(a)
As shown in the figure, a pn double heterojunction is formed between a semiconductor layer 301 and a semiconductor layer 302 with a different type of semiconductor layer 303 sandwiched therebetween. A strip-shaped upper electrode 304 having a width d is formed on the upper surface of the semiconductor layer 301 with a gap w in between.
A lower electrode 305 is formed on the entire lower surface of the semiconductor layer 302. When a forward voltage is applied between the upper electrode 304 and the lower electrode 305 and a current is injected, the current density of the semiconductor layer 303 changes as shown in FIG. 24(b).
It is high immediately below 04, and low between the two upper electrodes 304. Therefore, the refractive index of the central portion 309 of the semiconductor layer 303 becomes relatively larger than the refractive index of the surrounding portions. Since light is confined in a portion with a large refractive index, the semiconductor layer 303
An optical waveguide having a width w is formed in the central portion 309 of the waveguide.

However, in this proposed method, p
Since the optical waveguide is formed by passing a relatively large forward current through the n-junction, power consumption and heat generation increase. High power consumption makes high-speed operation difficult, and there is a problem in that the temperature of the junction of the elements increases due to heat generation, which deteriorates the efficiency of the integrated light-receiving and light-emitting elements.

[0008]

[Problems to be Solved by the Invention] As described above, in the conventional method of forming an optical waveguide, since the semiconductor layer is etched, the width and shape of the optical waveguide depend on the crystal orientation of the semiconductor layer. There is a problem in that it is difficult to form a wave path, and the chemically active etched surface easily deteriorates, reducing reliability.

In addition, in the proposed method for forming an optical waveguide, since current is passed through the semiconductor layer, power consumption and heat generation increase, making high-speed operation difficult and reducing the light receiving and light emitting efficiency of the optical device. The object of the present invention is to provide a semiconductor optical waveguide control device that consumes less power and can operate at high speed without etching the semiconductor layer.

0010

[Means for Solving the Problems] The principle of the present invention will be explained using FIGS. 1 to 8. A semiconductor optical waveguide control device according to the present invention (claim 1) is shown in FIG. Figure (a) is a perspective view of a semiconductor optical waveguide control device, figure (b) is a graph showing the refractive index distribution along the X-X' line, and figure (c) is a graph showing the refractive index distribution along the line X-X'.
FIG.

In the semiconductor optical waveguide control device according to the present invention (claim 1), the first semiconductor layer 1 and the multi-quantum well semiconductor layer 3 having a thickness h, which are formed by alternately laminating two semiconductor layers having different band gap energies, are used. Two band-shaped upper electrodes 4 having a width A are sandwiched between the second semiconductor layers 2 to form a double heterojunction, and are separated by a gap 44 of a distance w on the upper surface of the first semiconductor layer 1.
1 and 42, and two strip-shaped lower electrodes 51 and 52 with a width A are formed on the lower surface of the second semiconductor layer 2 with a gap 54 of a distance w between them.
is formed. upper electrodes 41, 42 and lower electrode 51,
A voltage source 7 is connected to the terminal 52 to apply an electric field to the multi-quantum well semiconductor layer 3 .

Here, light having a wavelength whose refractive index decreases when an electric field is applied to the multi-quantum well semiconductor layer 3 is selected as the light to be controlled. By applying a voltage between the upper electrodes 41, 42 and the lower electrodes 51, 52, as shown in FIG. 1(b),
Multi-quantum well semiconductor layer 3 corresponding to the gap 44 and the gap 54
The refractive index of the central portion 6 is increased to form an optical waveguide having a width w and a thickness h.

Note that the lower electrodes may be formed in the gap 54 without separating the lower electrodes 51 and 52. Alternatively, the semiconductor layer 2 may be formed of a material with high electrical conductivity to function as a lower electrode formed over the entire surface. A semiconductor optical waveguide control device according to the present invention (claim 2) is shown in FIG. Same figure (
(a) is a perspective view of the semiconductor optical waveguide control device, and (b) is a perspective view of the semiconductor optical waveguide control device.
is a graph showing the refractive index distribution along the line X-X';
c) is a graph showing the refractive index distribution along the Y-Y' line.

In the semiconductor optical waveguide control device according to the present invention (claim 2), a multi-quantum well semiconductor layer 3 in which two semiconductor layers having different band gap energies are alternately laminated is used as a first layer.
A double heterojunction is formed by sandwiching the semiconductor layer 1 and the second semiconductor layer 2, and a strip-shaped upper electrode 43 with a width w is formed on the upper surface of the first semiconductor layer 1, and a strip-shaped upper electrode 43 with a width w is formed on the lower surface of the second semiconductor layer 2. lol
Two band-shaped lower electrodes 53 are formed. A voltage source 7 is connected to the upper electrode 43 and the lower electrode 53, and an electric field is applied to the multiple quantum well semiconductor layer 3.

Here, light having a wavelength whose refractive index increases when an electric field is applied to the multi-quantum well semiconductor layer 3 is selected as the light to be controlled. By applying a voltage between the upper electrode 43 and the lower electrode 53, the upper electrode 43
The refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 corresponding to the lower electrode 53 is increased to form an optical waveguide. Note that the lower electrode 53 may be wider than the width w as long as it includes a portion corresponding to the upper electrode 43.

A semiconductor optical waveguide control device according to the present invention (claim 3) is shown in FIG. Figure (a) is a perspective view of a semiconductor optical waveguide control device, Figure (b) is a graph showing the refractive index distribution along the line X-X', and Figure (c) is a graph showing the refractive index distribution along the line Y-Y'. It is a graph showing refractive index distribution. The present invention (Claim 3)
The basic structure of the semiconductor optical waveguide control device according to the present invention is the same as that of the semiconductor optical waveguide control device according to the present invention described in claim 1, except that a refractive index distribution is built in in advance in the multi-quantum well semiconductor layer 3. It has characteristics. That is, FIG. 3(b)
As shown in FIG. 2, the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 is set to be lower than the refractive index of the surrounding portions when no voltage is applied. By doing so, by selecting light with a wavelength that increases the refractive index when an electric field is applied as the controlled light and applying a voltage between the upper electrodes 41 and 42 and the lower electrodes 51 and 52, as shown in FIG. (b)
As shown in FIG. 2, an optical waveguide can be formed by increasing the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 corresponding to the gaps 44 and 54.

It is preferable that the step size of the refractive index distribution formed in advance in the multi-quantum well semiconductor layer 3 is smaller than 1%. A semiconductor optical waveguide control device according to the present invention (claim 4) is shown in FIG. Figure (a) is a perspective view of a semiconductor optical waveguide control device, figure (b) is a graph showing the refractive index distribution along the line X-X', and figure (c) is a graph showing the refractive index distribution along the line Y-Y'.
It is a graph showing refractive index distribution along a line.

The basic structure of the semiconductor optical waveguide control device according to the present invention (claim 4) is the same as that of the semiconductor optical waveguide control device according to the present invention described in claim 2, but the multi-quantum well semiconductor layer 3 is The feature is that the rate distribution is built-in. That is, as shown in FIG. 4(b), the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 is set to be higher than the refractive index of the surrounding portions when no voltage is applied. By doing this, by selecting light with a wavelength whose refractive index decreases when an electric field is applied as the controlled light, and applying a voltage between the upper electrode 43 and the lower electrode 53, as shown in FIG. 4(b). As shown, gaps 44 and 5
By lowering the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 corresponding to 4, it is possible to control the central portion 6 so as not to guide light.

It is preferable that the step size of the refractive index distribution formed in advance in the multi-quantum well semiconductor layer 3 is smaller than 1%. A semiconductor optical waveguide control device according to the present invention (claim 5) is shown in FIG. FIG. 4(a) is a perspective view of a semiconductor optical waveguide control device, and FIG. 1(b) is a graph showing the refractive index distribution along the Y-Y' line.

In the semiconductor optical waveguide control device according to the present invention (claim 5), the multi-quantum well semiconductor layer 3 in which two semiconductor layers having different bandgap energies are alternately laminated is used as the first layer.
A double heterojunction is formed by sandwiching the semiconductor layer 1 and the second semiconductor layer 2, and two band-shaped upper electrodes 41 and 42 are formed on the upper surface of the first semiconductor layer 1 with a gap 44 of a distance w between them. A band-shaped upper electrode 45 is further formed in the gap 44, and two band-shaped lower electrodes 51 and 52 are formed on the lower surface of the second semiconductor layer 2 with a gap 54 of the interval w between them. A band-shaped lower electrode 55 is further formed. A voltage source 701 is connected to the upper electrodes 41 and 42 and lower electrodes 51 and 52, a voltage source 702 is connected to the upper electrode 45 and the lower electrode 55, and an electric field is applied to the multiple quantum well semiconductor layer 3.

Upper electrodes 41, 42 and lower electrodes 51, 52
By controlling the voltage applied between the upper electrode 45 and the lower electrode 55, and controlling the electric field of the central portion 6 to the multi-quantum well semiconductor layer 3 relative to that of the surrounding area, the multiple quantum well semiconductor layer 3 can be Optical waveguide characteristics can be controlled by changing the refractive index of the central portion 6 of the well semiconductor layer 3. Note that the lower electrodes 51, 52, and 55 may be formed over the entire surface without separating them. Alternatively, the semiconductor layer 2 may be formed of a material with high electrical conductivity to function as a lower electrode formed over the entire surface.

A semiconductor optical waveguide control device according to the present invention (claim 6) is shown in FIG. This figure is a perspective view of the semiconductor optical waveguide control device. In the semiconductor optical waveguide control device according to the present invention (claim 6), a multi-quantum well semiconductor layer 3 in which two semiconductor layers having different bandgap energies are alternately stacked is used as a first layer.
A double heterojunction is formed by sandwiching the semiconductor layer 1 and the second semiconductor layer 2, and two band-shaped impurity diffusion regions 101 and 102 are formed on the surface of the first semiconductor layer 1 with a gap w between them.
are formed, upper electrodes 401 and 402 are formed on these impurity diffusion regions 101 and 102, respectively, and a lower electrode 5 is formed on the lower surface of the second semiconductor layer 2.

The electric field distribution applied to the multiple quantum well semiconductor layer 3 is determined not by the pattern of the upper electrodes 401 and 402 but by the pattern of the impurity diffusion regions 101 and 102. A semiconductor optical waveguide control device according to the present invention (claim 7) is shown in FIG. This figure is a perspective view of the semiconductor optical waveguide control device. In the semiconductor optical waveguide control device according to the present invention (claim 7), a multi-quantum well semiconductor layer 3 in which two semiconductor layers having different band gap energies are alternately laminated is formed by a first semiconductor layer 1 and a second semiconductor layer 2. A double heterojunction is formed by sandwiching the strip-shaped semiconductor layers 103 and 104 with high electrical conductivity at a distance w on the first semiconductor layer 1. Electrodes 401 and 402 are formed, and a lower electrode 5 is formed on the lower surface of the second semiconductor layer 2.

The electric field distribution applied to the multi-quantum well semiconductor layer 3 is determined not by the pattern of the upper electrodes 401 and 402 but by the pattern of the semiconductor layers 103 and 104 having high electrical conductivity. A semiconductor optical waveguide control device according to the present invention (claim 8) is shown in FIG. Figures (a), (b), and (c) are perspective views of the semiconductor optical waveguide control device.

The semiconductor optical waveguide control device according to the present invention (claim 8) is characterized in that a pin junction is formed by a semiconductor layer sandwiched between an upper electrode and a lower electrode. In the semiconductor optical waveguide control device shown in FIG. 8(a), an impurity diffusion region 101 in which upper electrodes 401 and 402 are in contact
, 102 are formed of p-type semiconductor, and the first semiconductor layer 1
A multi-quantum well semiconductor layer 3 and a second semiconductor layer 2 are formed of an intrinsic type (i-type) semiconductor, and a semiconductor layer 201 with high electrical conductivity made of an n-type semiconductor is formed on the lower surface of the second semiconductor layer 2. Then, a lower electrode 5 is formed on the lower surface of this semiconductor layer 201. Impurity diffusion regions 101 and 102 (p type), first semiconductor layer 1 (i type), multi-quantum well semiconductor layer 3 (i type), second semiconductor layer 2 (i type), semiconductor layer 201 ( p-type), a pin junction is formed between the upper electrodes 401, 402 and the lower electrode 5.

In the semiconductor optical waveguide control device shown in FIG. 8(b), the impurity diffusion regions 101 and 102 with which the upper electrodes 401 and 402 are in contact are formed of a p-type semiconductor, and the first
The semiconductor layer 1 and the multi-quantum well semiconductor layer 3 are formed of an intrinsic type (i-type) semiconductor, and the second semiconductor layer 2
is made of an n-type semiconductor, and a lower electrode 5 is formed on the lower surface of the second semiconductor layer 2. Impurity diffusion regions 101, 102 (
between the upper electrodes 401, 402 and the lower electrode 5. ni p-i-n
A junction is formed.

In the semiconductor optical waveguide control device shown in FIG. 8(c), the semiconductor layers 103 and 104 with which the upper electrodes 401 and 402 are in contact are formed of a p-type semiconductor, and the first semiconductor layer 1 and the multiple quantum well The semiconductor layer 3 is formed of an intrinsic type (i-type) semiconductor, the second semiconductor layer 2 is formed of an n-type semiconductor, and the lower electrode 5 is formed on the lower surface of the second semiconductor layer 2. Semiconductor layers 103 and 104 (p-type), first semiconductor layer 1 (i-type) and multiple quantum well semiconductor layer 3 (i-type)
type) and the second semiconductor layer 2 (p type), the upper electrode 4
A pin junction is formed between 01 and 402 and the lower electrode 5.

[0028]

[Operation] Before explaining the operation of the semiconductor optical waveguide control device according to each claim, the change in refractive index when an electric field is applied to the multi-quantum well semiconductor layer 3 will be explained with reference to FIG. As shown in FIG. 9A, a multi-quantum well semiconductor layer 3 is sandwiched between a first semiconductor layer 1 and a second semiconductor layer 2, an upper electrode 4 is formed on the upper surface of the first semiconductor layer 1, and a second semiconductor layer 3 is sandwiched between the first semiconductor layer 1 and the second semiconductor layer 2. A lower electrode 5 is formed on the lower surface of the semiconductor layer 2 . A voltage source 7 is connected to the upper electrode 4 and the lower electrode 5, and an electric field is applied to the multiple quantum well semiconductor layer 3.

FIG. 9(b) shows the refractive index spectra at various applied electric fields. As the applied voltage V increases, the wavelength of the peak of the refractive index spectrum shifts to the longer wavelength side. That is, when the applied voltage V=0 [V] (a)
The refractive index peaks at the wavelength λ1, and when the applied voltage V = 1 [V] (b), the refractive index peaks at the wavelength λ2 (>λ1), and when the applied voltage V = 2 [V] (c) The refractive index peaks at wavelength λ3 (>λ2), and when the applied voltage V=3 [V] (d), the refractive index peaks at wavelength λ4 (>λ3).

Therefore, when the applied voltage V is changed,
The refractive index of the multi-quantum well semiconductor layer 3 can be changed for light of a certain wavelength. For example, using light of wavelength λ1, the voltage applied to the multi-quantum well semiconductor layer 3 is set to 0V.
When the voltage is changed from 1V to 1V, the refractive index decreases from the p point to the q point. When the voltage applied to the multi-quantum well semiconductor layer 3 is changed from 1V to 2V using light of wavelength λ2, the refractive index changes from the r point to the s point. Using light with a wavelength λ3, the multi-quantum well semiconductor layer 3
When the applied voltage is changed from 2V to 3V, the refractive index changes to become lower from point t to point u. Wavelength λ3
When the voltage applied to the multi-quantum well semiconductor layer 3 is changed from 0V to 2V using light, the refractive index changes from point v to t.
It changes so that it becomes higher to a point. Using light of wavelength λ4,
The voltage applied to the multi-quantum well semiconductor layer 3 is changed from 0V to 2V.
When the value is changed to V, the refractive index changes to become higher from the x point to the w point.

Note that as the multi-quantum well semiconductor layer 3, Ga
When using AlAs-based semiconductors, InGaAsP-based semiconductors, etc., the refractive index is approximately 1% in an electric field of 5 x 104 V/cm.
(approximately 0.03) change. Next, the operation of the semiconductor optical waveguide control device according to each claim of the present invention will be explained.

In the semiconductor optical waveguide control device according to the present invention (claim 1), for example, when light of wavelength λ1 is used, when the applied voltage is 0 V, the multi-quantum well semiconductor layer 3 as shown in FIG. The refractive index is the same in all regions, but when the applied voltage is set to 1 V, the refractive index around the central portion 6 changes from point p to point q in Figure 9(b), and the relative has a high refractive index and becomes an optical waveguide. therefore,
It is possible to control whether or not to guide light depending on whether or not a voltage is applied, and it can be applied to optical switches and modulators.

According to the present invention (claim 1), the shape of the optical waveguide can be defined only by the pattern of the upper electrode without processing the semiconductor layer as in the conventional method. Furthermore, since the refractive index can be changed simply by applying an electric field, power consumption can be reduced. moreover,
The response speed of refractive index change due to the application of an electric field is on the order of picoseconds, and the response speed when injecting a current (on the order of nanoseconds)
It is possible to operate at high speed compared to . Therefore, it is possible to realize a high-speed optical switch and a high-speed modulator with low power consumption.

In the semiconductor optical waveguide control device according to the present invention (claim 2), for example, when light of wavelength λ3 is used, when the applied voltage is 0 V, the multi-quantum well semiconductor layer 3 as shown in FIG. The refractive index of the central portion 6 is the same in all regions, but when the applied voltage is 2 V, the refractive index of the central portion 6 becomes
) changes from point v to point t, the refractive index of the central portion 6 becomes relatively high, and it becomes an optical waveguide. Therefore, it is possible to control whether or not to guide light depending on whether or not a voltage is applied, and it can be applied to optical switches and modulators.

According to the present invention (claim 2), since an optical waveguide can be formed by one upper electrode 43, the degree of integration of optical waveguides in an optical integrated circuit can be improved. In the semiconductor optical waveguide control device according to the present invention (claim 3 or 4), a refractive index distribution is created in the multi-quantum well semiconductor layer 3 in advance. In the semiconductor optical waveguide control device according to the third aspect, as shown in FIG. 3(b), the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 is made low. For example, when using light with wavelength λ1 and the applied voltage is 0V, the multi-quantum well semiconductor layer 3
The refractive index of the central portion 6 becomes lower and the light diverges, but when the applied voltage is set to 1 V, the refractive index around the central portion 6 becomes
(b) changes from point p to point q, relatively central part 6
The refractive index of the material increases, confining light and forming an optical waveguide.

In the semiconductor optical waveguide control device according to claim 4, as shown in FIG. 4(b), the multiple quantum well semiconductor layer 3
The refractive index of the central portion 6 is set to be high. For example, when using light with wavelength λ1 and the applied voltage is 0 V, the refractive index of the multi-quantum well semiconductor layer 3 becomes lower at the central portion 6 as shown in FIG. 4(b), and the light diverges; When the voltage is set to 1V, the refractive index of the central portion 6 becomes as shown in Fig. 9(b).
changes from point p to point q, and the refractive index of the central portion 6 becomes relatively high, confining light and forming an optical waveguide.

As described above, according to the semiconductor optical waveguide control device according to the third or fourth aspect, the guiding and unguiding of light can be controlled by the applied voltage. In the semiconductor optical waveguide control device according to the present invention (claim 5), the electric field applied to the central portion 6 of the multi-quantum well semiconductor layer 3 and its surroundings can be freely controlled by the central upper electrode 45 and the upper electrodes 41 and 42 surrounding it. can be controlled.

When voltage is applied only to the surrounding upper electrodes 41 and 42, the device operates in the same way as the semiconductor optical waveguide control device according to claim 1, and when voltage is applied only to the central upper electrode 45, the operation is as described in claim 1. This operates in the same manner as the semiconductor optical waveguide control device according to No. 2. If a constant voltage is always applied to the central upper electrode 45, it functions similarly to the semiconductor optical waveguide control device according to claim 3 in which a refractive index distribution is created in the multi-quantum well semiconductor layer 3, and the surrounding upper electrodes 41 , 42, the semiconductor optical waveguide control device operates similarly to the semiconductor optical waveguide control device according to claim 4, in which a refractive index distribution is created in the multi-quantum well semiconductor layer 3.

By appropriately controlling the voltages applied to the surrounding upper electrodes 41 and 42 and the voltage applied to the central upper electrode 45, an optical waveguide can be formed for light of a wide range of wavelengths. For example, if the voltage applied to the surrounding upper electrodes 41 and 42 is 2V,
When the voltage applied to the central upper electrode 45 is 1V, the refractive index for light with wavelength λ2 becomes point r and point s in FIG. is formed. The voltage applied to the surrounding upper electrodes 41 and 42 is 3V, and the voltage applied to the central upper electrode 45 is 2V.
Then, the refractive index for light with wavelength λ3 becomes point t and point u in FIG. 9(b), and the refractive index of the central portion 6 becomes relatively high, forming an optical waveguide.

In the semiconductor optical waveguide control device according to the present invention (claim 6 or 7), the upper electrodes 401 and 402 include the impurity diffusion regions 101 and 102 and the semiconductor layer 10 with high electrical conductivity.
Since it is connected to the first semiconductor layer 1 via 3 and 104, ohmic contact can be easily established. In the semiconductor optical waveguide control device according to the present invention (claim 8), the semiconductor layer sandwiched between the upper electrode and the lower electrode provides a pin
Since a junction is formed, insulation characteristics can be improved and leakage current can be reduced.

[0041]

Embodiment A semiconductor optical waveguide control device according to a first embodiment of the present invention will be explained with reference to FIG. This is an embodiment according to claim 1. Figure (a) is a cross-sectional view of the semiconductor optical waveguide control device, Figure (b) is a graph showing the electric field strength distribution along the line X-X', and Figure (c) is a graph showing the electric field intensity distribution along the line X-X'. It is a graph showing refractive index distribution.

The semiconductor optical waveguide control device according to this embodiment has an overall chip size of 300 μm in length and 300 μm in width. 8 nm thick InGaAs thin layer 31 and 8 nm thick I
25 layers of I
nGaAs thin layer 31 and 24 InGaAsP thin layers 32
A multi-quantum well semiconductor layer 3 is formed from the above. This multiple quantum well semiconductor layer 3 is sandwiched between a 1.5 μm thick InP upper cladding layer 1 and a 1.5 μm thick InP lower cladding layer 2 to form a double heterojunction. The InP upper cladding layer 1, the multiple quantum well semiconductor layer 3, and the InP lower cladding layer 2 are all non-doped.

Note that the multiple quantum well semiconductor layer 3 may be an Fe-doped high resistance type InGaAsP semiconductor. On the upper surface of the InP cladding layer 1, two band-shaped upper electrodes 41 and 42 made of three layers of Ti/Pt/Au and having a width of 5 μm are formed with a gap 44 of 10 μm in between, and on the lower surface of the InP cladding layer 2 made of Au. Two band-shaped lower electrodes 51 and 52 with a width of 5 μm are formed with a gap 54 of 10 μm in between.

In the semiconductor optical waveguide control device shown in FIG.
The multi-quantum well semiconductor layer 3 is sandwiched between an upper InP cladding layer 1 and a lower cladding layer 2 to form a three-layer structure, but the LOC has an optical confinement layer inserted above or below the multi-quantum well semiconductor layer 3 or on both upper and lower sides. In terms of structure, vertical direction (y direction)
can improve the confinement efficiency of optical waveguides. When a voltage is applied between the upper electrodes 41, 42 and the lower electrodes 51, 52, an electric field intensity distribution as shown in FIG. 10(b) is formed. When light of wavelength λ1 is used, the refractive index of the multi-quantum well semiconductor layer 3 changes from point p to point q in FIG.
The distribution is as shown in FIG. 10(c), and an optical waveguide is formed in the central portion 6 of the multi-quantum well semiconductor layer 3. A modification of the semiconductor optical waveguide control device according to this embodiment is shown in FIG.
) to (d).

In the semiconductor optical waveguide control device shown in FIG. 11(a), the lower electrode 5 formed on the lower surface of the InP lower cladding layer 2 has a width of 20 μm or more, and the upper electrode 41 has a width of 20 μm or more.
, 42 and the center of the lower electrode 5. The lower electrode 5 is formed of three layers of Ti/Pt/Au. In the semiconductor optical waveguide control device shown in FIG. 11(b), the InP lower cladding layer 2 has an impurity concentration of 5×1.
The lower electrode 5 is formed on the entire lower surface of the InP lower cladding layer 2 at a high concentration of 0.017 cm -3 or more.

In the semiconductor optical waveguide control device shown in FIG. 11(c), a multi-quantum well semiconductor layer 3 is formed by forming an InP upper cladding layer on an n-InP substrate 8 having a thickness of 100 μm and having an impurity concentration of 1×10 18 cm −3 or more. 1 and an InP lower cladding layer 2 sandwich a double heterojunction structure. A lower electrode 5 made of Au is formed on the bottom surface of the n-InP substrate 8. In the semiconductor optical waveguide control device shown in FIG. 11(d), the InP lower cladding layer 2 in FIG. 11(c) is omitted, and the multiple quantum well semiconductor layer 3 is directly formed on the n-InP substrate 8.

Next, the effects of the first embodiment of the present invention will be explained. First, according to this embodiment, since the shape of the optical waveguide is defined only by the pattern of the upper electrode, a uniform optical waveguide can be formed even if it is curved. Furthermore, since there is no need to perform etching that damages the surface as in the conventional method, there is no risk of deterioration in reliability.

Furthermore, since an optical waveguide can be formed by simply forming an upper electrode and a lower electrode, a plurality of optical waveguides can be formed using techniques similar to the electrode formation and wiring techniques used in ordinary semiconductor devices. Optical elements can be integrated. For example, by forming a plurality of optical elements having double heterojunctions with a multi-quantum well semiconductor layer as an intermediate layer on a wafer, and forming strip-shaped electrodes, the optical elements can be connected by an optical waveguide.

FIG. 12 shows a specific example of an optical integrated circuit in which a plurality of optical elements are integrated. Figure (a) is a plan view of the optical integrated circuit, Figure (b) is a left side view of the optical integrated circuit, Figure (c) is the left side view of the optical integrated circuit.
is a right side view of the optical integrated circuit. The optical integrated circuit in FIG. 12 is a heterodyne receiver. As shown in FIG. 12(a), the right end of the optical integrated circuit is provided with an entrance section 150 for inputting light from the outside and a laser 151, and the left end is provided with two photodetectors 152 and 153. is provided. Incidence section 150, laser 151 and photodetection sections 152, 15
3, upper electrodes 46, 47, 48, 49 having a pattern shape as shown in FIG. 12(a) are formed, and optical waveguides 61, 62, 63, 64,
Form 65. Incident light from the outside is guided by the optical waveguide 61, and laser light from the laser 151 is guided by the optical waveguide 6.
2, these lights are mixed by an optical waveguide 63, and the mixed light is branched by optical waveguides 64 and 65 and guided to photodetectors 152 and 153.

Furthermore, according to this embodiment, the refractive index can be changed simply by applying a voltage between the upper electrode and the lower electrode, so power consumption can be reduced. This is particularly effective when forming a large number of optical waveguides in a large-scale optical integrated circuit. Furthermore, the response speed of the refractive index change due to the application of an electric field is on the order of picoseconds, which enables faster operation than the response speed of generation and extinction of carriers (on the order of nanoseconds) when current is injected.

A semiconductor optical waveguide control device according to a second embodiment of the present invention will be explained with reference to FIG. This is an embodiment according to claim 2. Figure (a) is a cross-sectional view of the semiconductor optical waveguide control device, Figure (b) is a graph showing the electric field intensity distribution along the line X-X', and Figure (c) is a graph showing the electric field intensity distribution along the line X-X'. It is a graph showing refractive index distribution. The semiconductor optical waveguide control device of this embodiment has a width of 10 mm on the top surface of the InP upper cladding layer 1.
One strip-shaped upper electrode 43 with a width of 10 μm is formed on the lower surface of the InP lower cladding layer 2, and a strip-shaped lower electrode 53 with a width of 10 μm is formed on the lower surface of the InP lower cladding layer 2.
This embodiment differs from the first embodiment in that one is formed. The upper electrode 43 is formed of three layers of Ti/Pt/Au,
The lower electrode 53 is made of Au.

When a voltage is applied between the upper electrode 43 and the lower electrode 53, an electric field intensity distribution as shown in FIG. 13(b) is formed. For example, when light of wavelength λ4 in FIG. 9 is used, the refractive index of the multi-quantum well semiconductor layer 3 changes from point r to point w in FIG. 9, resulting in a distribution as shown in FIG. An optical waveguide is formed in the central portion 6 of the well semiconductor layer 3.

In this example as well, the lower electrode and the InP lower cladding layer are shown in FIGS. 11(a) to (d).
A similar modification is possible. According to this embodiment, since an optical waveguide can be formed by one upper electrode 43, the degree of integration of optical waveguides in an optical integrated circuit can be improved. Furthermore, when wavelength λ3 in FIG. 9 is used, depending on the magnitude of the applied voltage, the refractive index can be increased from point v (0V) to point t (2V), or decreased from point v (0V) to point u (3V). The third aspect of the present invention can be applied to optical waveguide and non-waveguide switches and optical modulators.
A semiconductor optical waveguide control device according to the embodiment will be described with reference to FIG. This is an embodiment according to claim 3. Same figure (
A) is a cross-sectional view of the semiconductor optical waveguide control device, and (b) is a cross-sectional view of the semiconductor optical waveguide control device.
is a graph showing the refractive index distribution along the line X-X'.

The semiconductor optical waveguide control device of this embodiment has the same basic structure as the first embodiment, but the first difference is that the multi-quantum well semiconductor layer 3 has a refractive index distribution built in in advance. This is different from the example. Impurity concentration is 1 x 1018 cm-
A band-shaped convex portion 801 having a width of 10 μm and a step difference of 1 μm is formed in the center of the n-InP substrate 8 having a thickness of 100 μm and a width of 1 μm. On the n-InP substrate 8 is InGaAs, which has a higher refractive index than InP and a lower refractive index than the multi-quantum well semiconductor layer 3.
A lower cladding layer 2 made of P is formed. InG
The aAsP lower cladding layer 2 has a thickness of 0.3 μm at the center.
The thickness of the surrounding portion is 1.3 μm. For this reason, a refractive index distribution in which the central portion 6 is small is created in advance in the multi-quantum well semiconductor layer 3.

According to this embodiment, since the refractive index distribution is created in advance in the multi-quantum well semiconductor layer 3, for example, when light of wavelength λ1 in FIG. 9 is used, the applied voltage is 0V.
In this case, as shown in FIG. 14(b), the refractive index of the multi-quantum well semiconductor layer 3 becomes lower at the central portion 6 and light diverges; however, when a voltage is applied, the refractive index around the central portion 6 decreases. 9(b), the refractive index of the central portion 6 becomes relatively high, confining light and forming an optical waveguide. As described above, according to this embodiment, it is possible to realize an optical modulator with a large change in optical waveguide and non-optical waveguide.

Note that if a refractive index distribution is created such that the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 is large, optical waveguide and optical non-guide can be similarly achieved by using light of wavelength λ3. can be controlled. A semiconductor optical waveguide control device according to a fourth embodiment of the present invention will be explained using FIG. 15. This is an embodiment according to claim 4. FIG. 5(a) is a sectional view of the semiconductor optical waveguide control device, and FIG. 2(b) is a graph showing the refractive index distribution along the line X-X'.

The semiconductor optical waveguide control device of this embodiment has the same basic structure as the second embodiment, but the second difference is that the multi-quantum well semiconductor layer 3 has a refractive index distribution built in in advance. This is different from the example. A band-shaped convex portion 110 having a width of 10 μm and a step difference of 1.2 μm is formed in the center of the InP upper cladding layer 1 . The central part of the InP upper cladding layer 1 has a thickness of 1
．． 5 μm, and the surrounding portion has a thickness of 0.3 μm. For this reason, a refractive index distribution in which the central portion 6 is large is created in advance in the multi-quantum well semiconductor layer 3.

According to this embodiment, since the refractive index distribution is created in advance in the multi-quantum well semiconductor layer 3, for example, when using the light of wavelength λ1 in FIG. 9(b), when the applied voltage is 0V, As shown in FIG. 14(b), the refractive index of the multi-quantum well semiconductor layer 3 is large in the central portion 6 and light is confined; however, when a voltage is applied, the refractive index of the central portion 6 changes as shown in FIG. 9(b). changes from point p to point q, the refractive index of the central portion 6 becomes relatively low, and light diverges. As described above, according to this embodiment, it is possible to realize an optical modulator with a large change in optical waveguide and non-optical waveguide.

Note that if a refractive index distribution is created such that the refractive index of the central portion 6 of the multi-quantum well semiconductor layer 3 is small, optical waveguiding and optical non-guiding can be similarly achieved by using light of wavelength λ3. can be controlled. Next, the light intensity modulation effect using the semiconductor optical waveguide control device according to the third or fourth embodiment of the present invention will be explained using FIG. 16.

It is assumed that the refractive index of the peripheral portion of the multi-quantum well semiconductor layer 3 of the semiconductor optical waveguide control device is n, and the refractive index of the central portion 6 is n1. When n>n1, the light incident on the central portion 6 is diffused from the central portion 6 to the peripheral portion and is not coupled to the fiber 27, as shown in FIG. 16(a). On the other hand,
In the case of n<n1, the incident light to the central portion 6 is as shown in FIG. 16(b
), it is confined in the central part 6 without diffusing to the surrounding parts, and passes through the lens 26 to the fiber 27.
are input and combined. In the semiconductor optical waveguide control device of the third or fourth embodiment, by controlling the applied voltage, it is possible to control the coupling to the fiber and perform optical intensity modulation.

A semiconductor optical waveguide control device according to a fifth embodiment of the present invention will be explained using FIG. 17. This is an embodiment according to claim 5. FIG. 5(a) is a sectional view of the semiconductor optical waveguide control device, and FIG. 2(b) is a graph showing the refractive index distribution along the line X-X'. The semiconductor optical waveguide control device of this embodiment has two upper electrodes 41 and 4 in the first embodiment.
In addition to 2, the width between these upper electrodes 41 and 42 is 10 μm.
A strip-shaped upper electrode 45 with a width of 6 μm is provided in the gap, and in addition to the two lower electrodes 51 and 52, a strip-shaped lower electrode 55 with a width of 6 μm is provided in the gap with a width of 10 μm between these lower electrodes 51 and 52. has been established. Upper electrodes 41 and 42 on both sides
A voltage source 701 is connected between the lower electrodes 51 and 52,
A voltage Vs is applied to the surrounding portion of the multi-quantum well semiconductor layer 3. A voltage source 702 is connected between the central upper electrode 45 and the lower electrode 55, and a voltage Vc is applied to the central portion 6 of the multi-quantum well semiconductor layer 3.

According to this embodiment, for example, if light with wavelength λ1 is selected in FIG. 9(b), the refractive index distribution, which was flat when the applied voltage was 0, will be changed as shown in FIG. 17(b). of,
When only the voltage Vs is applied, a refractive index distribution can be obtained in which the central portion 6 is high, and when only the voltage Vc is applied, a refractive index distribution can be obtained in which the central portion 6 is low. For this reason, by selecting the application of voltage Vs and voltage Vc, waveguiding,
A non-waveguide modulating optical waveguide can be realized.

Furthermore, according to this embodiment, since the voltage applied to the central portion 6 and the peripheral portion of the multi-quantum well semiconductor layer 3 can be controlled independently, the difference in refractive index for light of a certain wavelength can be controlled independently. An optimal voltage that maximizes the voltage can be applied to the central portion 6 and peripheral portions of the multi-quantum well semiconductor layer 3. Therefore, it is possible to form an optical waveguide that is optimal for light of various wavelengths, and it is possible to realize an optical waveguide that has wavelength selectivity.

In this example as well, the lower electrode and the InP lower cladding layer are shown in FIGS. 11(a) to (d).
A similar modification is possible. A semiconductor optical waveguide control device according to a sixth embodiment of the present invention will be explained using FIG. 18. This is an embodiment according to claims 7 and 8. Same figure (
a) is a sectional view of a semiconductor optical waveguide control device;

The semiconductor optical waveguide control device of this embodiment uses In
P upper cladding layer 1, multi-quantum well semiconductor layer 3, and InP
The lower cladding layer 2 is formed of an intrinsic (i-type) semiconductor. A strip of p-type InP with a width of 5 μm is formed on the upper surface of the i-type InP upper cladding layer 1 with a gap of 10 μm.
P semiconductor layers 103 and 104 are formed. p-type In
On the P semiconductor layers 103 and 104, 3 layers of Ti/Pt/Au are formed.
Upper electrodes 401 and 402 made of layers and having a width of 3 μm are formed. The impurity concentration of the p-type InP semiconductor layers 103 and 104 is preferably 1×10 18 cm −3 or more. Further, an n-type InP semiconductor layer 201 is formed entirely on the lower surface of the i-type InP lower cladding layer 2, and a lower electrode 5 made of Au is formed on the lower surface of the n-type InP semiconductor layer 201.

According to this embodiment, the upper electrodes 401 and 402
Since the lower electrode 5 is formed on the semiconductor layer with high impurity concentration, ohmic contact can be easily established. In addition, p-type InP semiconductor layers 103 and 104 and i-type InP semiconductor layers 103 and 104
P upper cladding layer 1, i-type multi-quantum well semiconductor layer 3, i
InP type lower cladding layer 2 and n type InP semiconductor layer 20
1 forms a pin junction, so the upper electrode 4
01, 402 and the lower electrode 5, by applying a reverse bias voltage to this pin junction, leakage current can be reliably prevented.

A semiconductor optical waveguide control device according to a seventh embodiment of the present invention will be described with reference to FIG. This is an embodiment according to claims 6 and 8. FIG. 2(a) is a sectional view of the semiconductor optical waveguide control device. In the semiconductor optical waveguide control device of this embodiment, an i-type multiple quantum well semiconductor layer 3 is directly formed on an n-InP substrate 8 with an impurity concentration of 1×10 18 cm −3 or more and a thickness of 100 μm. An i-type InP upper cladding layer 1 is formed on the well semiconductor layer 3. On the surface of the i-type InP upper cladding layer 1, p-type Zn diffusion regions 101 and 102 in which Zn is diffused are formed with a width of 5 μm and a depth of 1.5 μm with a gap of 10 μm in between. Upper electrodes 401 and 402 having a width of 3 μm are formed on the p-type Zn diffusion regions 101 and 102, and a lower electrode 5 is formed on the entire bottom surface of the n-InP substrate 8.

According to this embodiment, the upper electrodes 401 and 402
are connected to the p-type Zn diffusion regions 101 and 102, making it easier to establish ohmic contact. Also, p
If the Zn type diffusion regions 101 and 102 are deepened, the i type InP
Even if the upper cladding layer 1 is thick, the p-type Zn diffusion region 1
Since the tips of the diffusion portions 01 and 102 can be brought close to the multiple quantum well semiconductor layer 3, a large electric field can be applied to the multiple quantum well semiconductor layer 3 at a lower voltage.

Furthermore, p-type Zn diffusion regions 101 and 102
Since a p-i-n junction is formed by the i-type InP upper cladding layer 1, the i-type multiple quantum well semiconductor layer 3, and the n-InP substrate 8, the upper electrodes 401, 402 and the lower electrode 5
Therefore, by applying a reverse bias voltage to this pin junction, leakage current can be reliably prevented.

An optical integrated circuit according to an eighth embodiment of the present invention will be explained using FIG. 20. Figure (a) is a plan view of the optical integrated circuit, Figure (b) is an end view of the optical integrated circuit taken along the X1-X1' line, and Figure (c) is the X2-X side view of the optical integrated circuit.
The end view taken along line 2' (d) shows the Z of the optical integrated circuit.
FIG. 3 is an end view taken along the -Z' line. The optical integrated circuit of this embodiment includes a semiconductor optical waveguide control device and a DF according to the fifth embodiment.
This is a laser light source with a modulator that is integrated with a B laser. In FIG. 20(a), the laser section 9 is on the left, and the modulator section 10 is on the right.

On a 100 μm thick n-InP substrate 8 with an impurity concentration of 1×10 18 cm −3 or more, a multi-quantum well semiconductor layer 3 is formed by forming an InP upper cladding layer 1 and an InGaAsP layer.
A double heterojunction structure sandwiched between the lower cladding layer 2 and the lower cladding layer 2 is formed. A lower electrode 5 is formed on the entire bottom surface of the n-InP substrate 8 . The laser section 9 on the right side has a length of 300 μm. A Zn diffusion region 106 with a width of 6 μm is formed on the surface of the InP upper cladding layer 1, and an upper electrode 46 is formed on the Zn diffusion region 106. In the laser section 9, the periphery of the upper electrode 46 is etched away until it reaches the n-InP substrate 8, forming a mesa shape with a width of 10 μm. n-InP substrate 8 and InP lower cladding layer 2
At the interface, the pitch is about 200 nm and the depth is about 200 nm.
A corrugation 16 of nm is formed.

The left modulator section 10 has a length of 300 μm. Two Zn diffusion regions 101 and 10 with a width of 6 μm are formed on the surface of the InP upper cladding layer 1 with a gap of 10 μm in between.
A Zn diffusion region 105 having a width of 6 μm is formed in a gap having a width of 10 μm between these Zn diffusion regions 101 and 102. A central Zn diffusion region 105 in the modulator section 10 is formed at a position that coincides with a Zn diffusion region 106 in the laser section 9. Zn diffusion region 101,
Upper electrodes 41, 42, 45 are formed on 102, 105.

The multi-quantum well semiconductor layer 3 functions as an active layer in the laser section 9 and as an optical waveguide layer in the modulator section 10. Laser light oscillated in the multiple quantum well semiconductor layer 3 as the active layer of the laser section 9 can be made to directly enter the multiple quantum well semiconductor layer 3 as the optical waveguide layer of the modulator section 10 . According to this example, the laser and the modulator can be formed on a substrate having the same layer structure, and the active layer of the laser and the active layer of the modulator are continuous, so manufacturing is easy and loss at the connection part is reduced. can be made smaller.

Note that FIG. 21 shows the spectrum of the absorption coefficient α and the spectrum of the refractive index n of the multi-quantum well semiconductor layer 3. λg is a wavelength corresponding to bandgap energy in the absence of an electric field, and λL is a wavelength for laser oscillation. When a reverse voltage is applied to the multi-quantum well semiconductor layer 3, both the peak of the absorption spectrum and the peak of the refractive index spectrum move to the right in FIG. Therefore, when a predetermined voltage is applied, the same multi-quantum well semiconductor layer 3 can be used both as an optical waveguide and as a photodetector for the same wavelength. Moreover, it is also possible to cause laser oscillation by using the multi-quantum well semiconductor layer 3 as an active layer.
By using the multi-quantum well semiconductor layer 3 of this example, it is possible to form not only the above-mentioned laser and modulator but also other optical elements such as a photoreceiver and an amplifier on a substrate having the same layer structure. . Furthermore, by using the optical waveguide control device according to the present invention, it is possible to realize a device in which these optical elements are directly coupled.

[0075]

As described above, according to the present invention, it is possible to realize a semiconductor optical waveguide control device that consumes little power and can operate at high speed without etching the semiconductor layer.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 1).

FIG. 2 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 2).

FIG. 3 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 3).

FIG. 4 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 4).

FIG. 5 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 5).

FIG. 6 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 6).

FIG. 7 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 7).

FIG. 8 is a diagram showing a semiconductor optical waveguide control device according to the present invention (claim 8).

FIG. 9 is a graph showing changes in refractive index when an electric field is applied to a multi-quantum well semiconductor layer.

FIG. 10 is a diagram showing a semiconductor optical waveguide control device according to a first embodiment of the present invention.

FIG. 11 is a diagram showing a modification of the semiconductor optical waveguide control device according to the first embodiment of the present invention.

FIG. 12 is a diagram showing a specific example of an optical integrated circuit in which a plurality of optical elements are integrated using the semiconductor optical waveguide control device according to the first embodiment of the present invention.

FIG. 13 is a diagram showing a semiconductor optical waveguide control device according to a second embodiment of the present invention.

FIG. 14 is a diagram showing a semiconductor optical waveguide control device according to a third embodiment of the present invention.

FIG. 15 is a diagram showing a semiconductor optical waveguide control device according to a fourth embodiment of the present invention.

FIG. 16 is an explanatory diagram of a light intensity modulation effect using a semiconductor optical waveguide control device according to a third or fourth embodiment of the present invention.

FIG. 17 is a diagram showing a semiconductor optical waveguide control device according to a fifth embodiment of the present invention.

FIG. 18 is a diagram showing a semiconductor optical waveguide control device according to a sixth embodiment of the present invention.

FIG. 19 is a diagram showing a semiconductor optical waveguide control device according to a seventh embodiment of the present invention.

FIG. 20 is a diagram showing a semiconductor optical waveguide control device according to an eighth embodiment of the present invention.

FIG. 21 is a graph showing an absorption spectrum and a refractive index spectrum of a multi-quantum well semiconductor layer.

FIG. 22 is a diagram showing a conventional optical waveguide.

FIG. 23 is a diagram showing a conventional optical waveguide.

FIG. 24 is a diagram showing a proposed semiconductor optical waveguide control device.

[Explanation of symbols]

1...First semiconductor layer 2...Second semiconductor layer 3...Multi-quantum well semiconductor layer 5...Lower electrode 6...Central portion 7...Voltage source 44...Gaps 41, 42, 43, 45...Upper electrode 54...Gap 51 , 52, 53, 55...lower electrodes 101, 102...impurity diffusion regions 103, 104...semiconductor layers 401, 402...upper electrodes 701, 702...voltage source 1...InP upper cladding layer 2...InP lower cladding layer 3...multiquantum Well semiconductor layer 5...lower electrode 8...n-InP substrate 9...laser section 10...modulator section 16...corrugation 26...lens 27...optical fiber 31...InGaAs thin layer 32...InGaAsP thin layer 46, 47, 48, 49... Upper electrodes 51, 52, 53, 55...lower electrodes 61, 62, 63, 64, 65...optical waveguides 101, 10
2, 105, 106...p-type Zn diffusion regions 103, 104
...p-type InP semiconductor layer 110...protrusion 150...incident part 151...laser 152, 153...photodetector 201...n-type InP semiconductor layer 801...protrusion 301, 302, 303...semiconductor layer 304...upper electrode 305...lower part Electrode 306...Convex portion 308...Central portion 309...Central portion

Claims (8)

[Claims] 1. A multi-quantum well semiconductor layer in which two semiconductor layers having different band gap energies are alternately stacked,
a first semiconductor layer heterojunctioned to the first surface of the multi-quantum well semiconductor layer; and a second semiconductor layer of the multi-quantum well semiconductor layer.
a first upper electrode and a second upper electrode formed on the first semiconductor layer and extending substantially parallel to each other with a predetermined gap therebetween; a lower electrode formed on a second semiconductor layer, and by controlling a voltage applied between the first and second upper electrodes and the lower electrode, A semiconductor optical waveguide control device characterized by forming an optical waveguide based on a difference in refractive index in a portion corresponding to a gap. 2. A multi-quantum well semiconductor layer in which two semiconductor layers having different band gap energies are alternately laminated,
a first semiconductor layer heterojunctioned to the first surface of the multi-quantum well semiconductor layer; and a second semiconductor layer of the multi-quantum well semiconductor layer.
a second semiconductor layer heterojunctioned to a surface of the semiconductor layer, a third upper electrode having a predetermined width extending on the first semiconductor layer, and a lower electrode formed on the second semiconductor layer. the second lower electrode of the multi-quantum well semiconductor layer by controlling the voltage applied between the third lower electrode and the lower electrode.
A semiconductor optical waveguide control device characterized in that an optical waveguide is formed in a portion corresponding to a lower electrode based on a difference in refractive index. 3. The semiconductor optical waveguide control device according to claim 1, wherein the refractive index of a portion of the multi-quantum well semiconductor layer corresponding to the predetermined gap is different from the refractive index of other portions. Semiconductor optical waveguide control device. 4. The semiconductor optical waveguide control device according to claim 2, wherein the refractive index of a portion of the multi-quantum well semiconductor layer corresponding to the third electrode is different from the refractive index of other portions. Semiconductor optical waveguide control device. 5. The semiconductor optical waveguide control device according to claim 1, wherein the semiconductor layer is formed on the predetermined gap of the first semiconductor layer and extends substantially parallel to the first and second upper electrodes. A semiconductor optical waveguide control device further comprising a fourth upper electrode. 6. The semiconductor optical waveguide control device according to claim 1, wherein the first or second electrode is located under at least one of the first to fourth upper electrodes and the lower electrode. A semiconductor optical waveguide control device characterized in that an impurity diffusion region is formed in a semiconductor layer. 7. The semiconductor optical waveguide control device according to claim 1, wherein at least one of the first to fourth upper electrodes and the lower electrode contains impurities with high electrical conductivity. A semiconductor optical waveguide control device, characterized in that the semiconductor optical waveguide control device is in contact with the first or second semiconductor layer via a doped semiconductor layer. 8. The semiconductor optical waveguide control device according to claim 1, wherein the multi-quantum well semiconductor layer, the first semiconductor layer, and the second semiconductor layer are sandwiched between the upper electrode and the lower electrode. A semiconductor optical waveguide control device characterized in that a p-n junction between semiconductor layers is formed as a p-i-n junction by an impurity diffusion region and a semiconductor layer doped with impurities.