JPH083594B2 - Light switch - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical switch that electrically switches a transmission path of an optical signal, and more specifically, it can switch visible light useful for plastic fiber transmission and optical measurement. About the light switch.

[Prior art]

Utilization of optical fiber communication has greatly developed as a transmission means of the information-oriented society due to the practical use of semiconductor lasers and the reduction of loss of silica optical fiber. For signal transmission, the use of optical transmission has been promoted by improving the quality of the plastic fiber. Further, in optical measurement and the like, the use of a laser in the visible range that can be visually recognized by humans and the development of a visible range semiconductor laser to support it have been promoted. (For example
Appl Phys. Lett. 48 (3), P207 1986) Conventionally, a mechanical switch has been typical as a switch for switching these optical signals to different transmission lines. Figure 4 shows the principle. The light from the input fiber 22 is converted into parallel light by the lens 23, totally reflected by the movable prism 24, and introduced into the output fibers 1 and 26 via the lens 25. The light output can be switched to the output fiber 2.29 by moving the prism downward.

On the other hand, as a configuration for electrically switching without moving parts, as described in Electronic Technology Vol. 26, No. 2, P35, one using the electro-optical effect of the PLZT ferroelectric thin film on the sapphire substrate or published by Ohmsha Optical integrated circuit As described in P309 on February 25, 1960, one using the electro-optical effect of Li single crystal has been known. Nikkei Microdevices March 1986 issue
As described in P58, an optical switch has been proposed in which the refractive index is changed by carrier injection into a waveguide using an InGaAsP-based compound semiconductor.

The basic principle of these thin film optical switches is shown in FIG. A stripe-shaped electrode is provided at the crossing portion 28 of the crossed waveguide (however, in the case of a dielectric, a parallel counter electrode is used, and due to the electro-optic effect, and in the case of a semiconductor, carrier injection is performed by the upper and lower electrodes) to lower the refractive index in a stripe shape By the mirror
The light wave 31 forming 29 and propagating from the input waveguide 1.30 is totally reflected to switch from the output waveguide 3.32 to the output waveguide 4.37.

[Problems to be solved by the invention]

However, the above-mentioned conventional techniques have the following drawbacks and have been desired to be improved.

1. The movable prism type switch has a slow response and a large variation in the assembly accuracy, and the entire switch becomes large.

2. It is difficult to obtain high quality sapphire and LiNbO ₃ inP using a single crystal substrate.

3. GaInAsP and other materials using III-V group compound semiconductors such as GaAs are small in size and can be used as a monolith with a light receiving element, but the wavelength corresponding to the fundamental absorption edge is long and the absorption loss in visible light is too large. Is not suitable as a waveguide.

Therefore, the present invention eliminates such a problem, and an object thereof is to provide an inexpensive and compact optical switch capable of switching visible light at high speed by electrical control.

[Means for solving problems]

The optical switch of the present invention comprises a cladding layer made of n-type ZnS and an n-type ZnSxSe ₁ -x (where 0x <
An optical switch comprising a crossed waveguide layer formed of 1) and electrodes formed on the crossing portion of the waveguide layer and the substrate side.

[Action]

According to the above configuration of the present invention, the carrier injected from the Schottky electrode into the waveguide layer raises the Fermi-Millbell and apparently spreads the bandgear to lower the effective refractive index, so that the light wave that has been transmitted up to that time is transmitted to the electrode. At this point, the light is totally reflected and the light can be switched.

 The present invention will be described below based on examples.

[Embodiment 1] FIG. 1 is a structural top view of a ridge type optical switch according to the present invention, and FIG. 2 is a structural sectional view of a switch part.
A cladding layer 2 consisting of a non-doped ZnS epitaxial layer is formed on a P-type Si single crystal substrate 1 by 1 μ, and a stripe-shaped low resistance n-type layer 3 is formed in the center thereof. Further, a ZnS _0.5 Se _0.5 mixed crystal layer 4 having a carrier concentration of 10 ¹⁵ to 10 ¹⁴ / cm ³ was epitaxially grown for 3 μm, and then dry etching or the like was used to remove parts other than the cross-type ridge portion 5 by 1.7 μ etching. Use as a waveguide.

In addition, a stripe-shaped low resistance n is provided on the ridge on the intersection.
The mold layer 6 is formed to a depth of 1.7 μ, and the SiO ₂ passivation film 7 is formed to a thickness of 0.5 μ except for the low resistance stripe portion, and a carrier injecting electrode 8 is formed on the SiO ₂ passivation film 7 and an AuGe electrode 9 is formed on the GaAs substrate. .

The width of the ridge is 10μ at the waveguide and 15μ at the crossing.
Also, the width of the low resistance part provided for current confinement is 1μ and the length
At 200μ, the waveguide crossing angle 10 is 5 °. By inputting a negative DC number V to the In electrode 8 and to the AuGe electrode 9, a light input terminal 1.
The He-He laser light (wavelength 0.633μ) put in 11 caused total internal reflection and was switched from the output end 3.12 to 4.13. The extinction ratio was 20 dB.

Although the size related to the shape of the above-mentioned waveguide is merely one example, unless the cladding layer and the low resistance striation portion provided at the intersection are formed, the spatial steepness of the refractive index change due to the spread of the carrier. Lost, inefficient total reflection,
The extinction ratio was too high.

Moreover, in the fabrication of this element, in the thin film formation,
Low-temperature processes such as the MBE method and MO-CVD method are excellent in that low impurity and defect concentrations are obtained, and ion implantation is preferable for the low resistance portion. Further, in forming the ridge portion of the waveguide, the ion beam etching is preferable because the shape of the wall surface has a great effect on the scattering loss, but it is not limited to this.

[Embodiment 2] FIG. 3 is a sectional view showing the configuration of an optical switch using a dielectric loaded type as a waveguide layer.

As in Example 1, low resistance n-type ZnS was formed on a P-type Si single crystal substrate.
With a cladding layer of 1μ and a carrier concentration of 10 ¹⁴ cm Zn
S _0.8 Se _0.2 Waveguide layer 15 of 1μ, and n
-Type low resistance ZnS layer 16 is formed with a thickness of 1.5μ, and the width is 1 at the intersection.
SiO ₂ passivation film 17 leaving a window of μ and length of 300μ
Is formed by 0.5 μ, and then the In electrode 18 is formed. On the other hand, on the substrate side, the substrate is arranged in a striped pattern 19 facing the window.
To the exposed cladding layer part with a width of 1
After forming the SiO ₂ passivation film 20 leaving a μ length of 300μ, the Au electrode 21 is formed.In this element, the end point of etching at the time of forming a waveguide may be stopped by detecting Se. Manufacture is excellent in that switching can be performed without selectively forming the low resistance portion in the cladding layer and the recess portion. The wavelength of the light used extends from infrared to about 0.5μ.

In this device, the optical switch part needs to be at most 2 mm square.
Since the substrate is used, it has a mass-producible structure by MO-CVD method or the like.

〔The invention's effect〕

As described above, according to the present invention, a cladding layer made of n-type ZuSxSe ₁ -x (where 0 <x1) and n-type ZnSySe (1-y) (where 0y <1 and y are provided on the Si single crystal substrate.
<X) A cross-type waveguide layer and an electrode formed on the cross-section of the waveguide layer and on the side of the substrate to provide an inexpensive and compact optical switch capable of electrically and rapidly switching visible light. Has the effect of

This makes it cheaper than conventional plastic fiber,
The spread of the optical switch according to the present invention in place of the optical switch that has not been price-matched with the optical transmission medium, information processing in offices, automobile aircraft, or transmission between devices, and other noise in a large amount in a short distance. I am convinced that the role of the present invention in the construction of a safe information processing network for the above is immeasurable.

[Brief description of drawings]

FIG. 1 is a structural top view of a ridge type optical switch of the present invention. FIG. 2 is a sectional view showing the configuration of the ridge type optical switch of the present invention. 1: Si substrate, 2: Cladding layer 3: Low resistance layer, 4: ZnS _0.5 Se _0.5 mixed crystal layer 5: Ridge part, 6: Low resistance layer 7: SiO ₂ film, 8: In electrode 9: AuGe electrode, 10 : Crossing angle 11: Input ends 1, 12, 13: Optical output end FIG. 3 is a sectional view showing the structure of the laminated optical switch of the present invention. 14: Cladding layer, 15: Waveguide layer 16: Low resistance layer, 17: SiO ₂ film 18: In electrode, 19: Substrate window 20: SiO ₂ , 21: Au electrode Fig. 4 shows a conventional mechanical switch. Configuration 22: Input fiber, 23,25: Condenser lens 26,27: Output fiber 24: Movable prism Fig. 5 shows basic principle of thin film optical switch Fig. 28: Intersection, 29: Mirror 30: Input waveguide, 31: Lightwave 32, 33: Output waveguide

Claims (3)

[Claims] 1. A cladding layer made of n-type ZnSxSe ₁ -x (where 0 <x1) and an n-type ZnSySe (1) on a Si single crystal substrate.
-Y) (where 0y <1 and y <x), and an optical switch comprising an intersecting waveguide layer and electrodes formed on the waveguide layer intersection and the substrate side. 2. A stripe type low resistance region is provided in a part of the ridge layer at the intersection and the cladding layer, and the waveguide layer is a ridge type waveguide. Light switch described. 3. The waveguide layer is an n-type ZnSySe (1-y) (provided that 0
y <1) consisting of a laminated waveguide in which n-type ZnSzSe1-z (where 0 <Z1 and Z <x) stripes are provided on a thin film,
A striped metal electrode is formed on the laminated portion of the intersecting portion, and the substrate is etched corresponding to the striped electrode on the substrate side to form a SiO ₂ passivation film except the exposed portion of the buffer layer. The optical switch according to claim 1, wherein a striped metal electrode is provided.