JPS59148031A - Optical switch - Google Patents

Abstract

PURPOSE:To make the temperature variation characteristics of a light guide sharply during the application of a specific voltage and improve the responsibility, and to perform optical switching by applying the specific voltage to a temperature gradient generating means when a switch circuit turns on rising and off falling. CONSTITUTION:The optical switch is providing a main light guide 29, light guide 30 having branch light guides 33 and 34, and the temperature gradient generating means 10 provided near the guide 30 and the branch point of the guides 33 and 34 of the guide 29, and consists of a switch circuit 22 which turns on and off the means 10 and a voltage source 21 which supplies a voltage which is than and has the same polarity with a steady on voltage to said means 10 only during turning-on operation in response to the on-off operation of the circuit 22 and a specific voltage having the opposite polarity of the steady on voltage only during turning off operation. Then, the means 10 is turned on and off to change light propagation directions in the light guide.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of the Invention The present invention relates to an optical switch, and particularly to an optical switch using thermo-optical effect gold.

(b) Prior art and its problems An optical switch has already been proposed in which a temperature distribution is generated on an optical waveguide by a temperature gradient generating means, and a light beam is turned on and off by the so-called thermo-optic effect. This type of optical switch uses a cooling body, for example, as a temperature gradient generating means, and its configuration is as shown in FIG. It consists of an optical waveguide 4 with 7 to turn on/off the power supply to the cooling body 6,
The cooling effect of the cooling body 6 is activated/deactivated, and the light propagation direction of the optical waveguide 4 is switched.

In this conventional optical switch, a constant DC voltage is applied to a cooling body as a means for generating a temperature gradient, and the direction of light propagation is switched by turning this applied voltage on and off. The shortcoming is that the responsiveness of optical switching to ON/A-OFF is poor, and high-speed optical switching cannot be performed.

To further explain this drawback, the waveform showing the switching operation of the conventional optical switch is as shown in FIG. When the switch 8 is turned on/off, a constant voltage V is applied to the cooling body B while the switch 8 is on, as shown in FIG. 6(a). The temperature of the leading waveguide 4 changes exponentially according to the rise or fall of the applied voltage [Fig.
)), depending on the degree of temperature change, the optical power of the branched optical waveguide A becomes as shown in Fig. 6(c), and with respect to the applied voltage,
There is a fairly large delay c'rai both when on and off.
Td2: about 100m5eC) rises,
Or fall. This delay means poor optical switching responsiveness.

(c) Purpose of the invention The purpose of the present invention is to eliminate all of the above-mentioned drawbacks, provide good responsiveness,
An object of the present invention is to provide an optical switch capable of high-speed optical switching.

) Structure and effect of the invention In order to achieve the above object, the optical switch of this invention has the following features:
An optical waveguide having a main optical waveguide and a branch optical waveguide, a temperature gradient generating means provided near a branch point between the main optical waveguide and the branch optical waveguide of the optical waveguide, and turning on/off the operation of the temperature gradient generating means. A switch circuit that turns off, and responds to the on/off of this switch circuit, applies a voltage of the same polarity that is greater than the steady on voltage only at the time of the on rise, and a predetermined voltage of the opposite polarity to the steady on voltage only at the time of the off fall. and a voltage source supplied to the temperature gradient generation means via the switch circuit, and the direction of light propagation within the optical waveguide is switched by turning on/off the temperature gradient generation means.

According to the optical switch of the present invention, the voltage of the same probe is lower than the steady on voltage only when the switch circuit turns on, and the predetermined voltage with the opposite polarity to the steady on voltage is set only when the switch circuit turns off. Since it is applied to the generating means,
Optical switching can be performed in which the temperature change characteristics of the optical waveguide at the time of on-rise and off-fall are steep, and the υ response is poor.

Furthermore, if the optical switch of the present invention is applied to an optical bypass switch for optical fiber loop transmission, the bypass switching time for the optical fiber loose in the event of an abnormality in the optical data highway system will be shortened, the system down time can be completely reduced, and the reliability of the system can be improved. You can improve.

(e) Description of examples Hereinafter, the present invention will be explained in more detail with reference to Examples.

2 to 4 show a cooling body part 10i which is included in an optical switch in which the present invention is implemented. However, the main body of this cooling body part 10 itself has not been proposed yet. There is no difference from the optical switch.

1, in each figure, a rectangular hole 12 in the shape of a tanzak (length 7M, width 21m) is formed in a polymer film 11 such as bisphenol-based polycarbonate (PCZ) by the gear A1 nuting method. 12, for example N-type bismuth telluride (N-Bi2Tea) 13 and P-type bismuth telluride CP-B i zTe3)1
4 is buried with the interface insulated with a coating film.

Furthermore, a film thickness of 60 mm is applied to the front and back surfaces of the polymer film 11.
0071m AU electric 11g 15, 16 and 17
is formed by vapor deposition. The above N-type bismuth telluride 13
, P-type bismuth telluride 14 and (f I[pole 15°16.1'7) constitute a cooling body 18.The two faces of the electrode 15.16 are electrically insulators. While a mica film 19, which is a thermal conductor, is disposed, green and adhesive are applied to the back side of the heat sink 20, which is made of processed aluminum alloy, for example, to aid heat conduction, and this back side is coated with the above-mentioned method. The heat sink 2D and the polymer film 11f are placed on the mica film 19 and are in close contact with each other.Lead wires 23. 24 is connected.

In the cooling body section 10, when the switch 12 is turned on and ten voltages are applied to the electrode 15 and one voltage is fully applied to the electrode 16, the inside of the N-type bismuth telluride is attracted to the electrode 15, and the P-type Internal holes of bismuth telluride 14 form electrode 16
is attracted to. As a result, power supply 21 → switch 22 → lead wire 23 → IHi1i? 15→N-type bismanuth telluride 13→'fi17-P-type bismanuth telluride 14→electrode 1
A current flows in the order of 6→lead wire 24→power supply 21. When this current flows through the N-type telluride binumanu 13 and the P-type telluride binumanu 14, it is caused by the Bertier effect.

Heat absorption occurs at the contact surface between the electrode 17, the N-type bismanuth telluride 13, and the p-type bismanuth telluride 14.

Therefore, when the electrode 17 is brought into contact with, for example, a polymer optical waveguide, a temperature drop occurs due to electronic cooling of the optical waveguide portion.

FIG. 5 is a structural diagram and a circuit diagram of an optical switch showing an embodiment of the present invention. The optical switch shown here uses a plastic plate 25. as a protective substrate. Cladding layers 26 and 27.
Polymer film 28. Cooling body part 10. It is composed of a power source 21 and a switch circuit 22, and the polymer film 2B has a main optical waveguide 29 and an asymmetric branch optical waveguide 30.
An asymmetrical Y-shaped optical waveguide 31 is formed. An input optical fiber 32 is coupled to the input side of the main optical waveguide 29 so that incident light is input thereto, and to the output sides of the main optical waveguide 29 and the branch optical waveguide 30.

Each output optical fiber 3 is connected so that the output light is guided out.
3.34 are combined.

The cooling body section 10 illustrated in FIGS. 2 to 4 is 1.
Rizuki is raped.

For the polymer film 2, bisphenol polycarbonate-1-P CZ'i was used as the base material, methyl acrylate lI/M A f was used as the monomer, methylene chloride CH2Cβ3 was used as the solvent, and benzoin ethylene ether/l was used as the photosensitizer. /BZEE with hydroquinone H as an inhibitor
A cast solution containing Q blended into a semi-solid state in the form of a sheet using the canuteing method.

The film thickness is, for example, 50 (71 m). Note that the optical waveguide 31 disposed within the polymer film 28 is formed by providing a refractive index difference using selective photopolymerization.

The cladding layers 26 and 27 are formed by coating the front and back surfaces of the polymer film 28 with, for example, a water-based varnish having a low refractive index.

The cooling body 18 of the cooling body section 10 is connected to the branch point 6 of the optical waveguide 60.
5 is disposed along the nine-branch optical waveguide 30 and is closely attached to the surface of the polymer film 28. This close contact is achieved by mechanical pressure bonding using adhesives, screws, etc.

The power supply circuit 21 includes a first battery 36, a series circuit of a resistor R1 and a normally open switch 38, a resistor R2, and a transistor Tr.
series circuits are connected in parallel, resistor R1 and normally open switch 3
The connection point of 8 is connected to the base of the transistor Tr, and the collector of the transistor Tr is a capacitor) JC, resistor R
5 to the negative side of the battery 56, and furthermore, the connection point between the capacitor C and the resistor R3 is connected to the negative side of the battery 37. The negative electrode side of the battery 56 is connected to the power source 16 of the cooling body section 10 via the lead wire 24.

The switch circuit 22 consists of a normally open switch 9 and a normally closed switch 40, one end of the normally open switch 69 is connected to the positive end of the battery 57, and one end of the normally closed switch 4° is connected to the battery 3.
Further, the other ends of both switches 39 and 40 are commonly connected and connected to the electrode 15 of the cooling body section 10 via a lead wire 26. In addition, the normally open switch 38.3
9 are turned on at the same time, and the normally closed switch 4G is turned off at the same time as the normally open switch 8.39 is turned on.

The power supply circuit 21 and the switch circuit 22 shown in FIG. 7(a)
) is created, and this voltage is applied to lead wire 2.
3.24 to electrode 15.16.

Here, the voltage generation operation shown in FIG. 7(a) by the power supply circuit 21 and the switch circuit 22 will be explained. First, when the switch 3M9 is turned on with the applied voltage being 0 (time ti), the transistor Tr is turned off and the batteries 36 and 67 are connected through the capacitor C.
The wake-up force of 36.37 is added and outputted.If the wake-up force of 36.
becomes. Thereafter, the capacitor C is charged and a voltage of -V is generated across it, so the output voltage becomes +V after a certain period of time (time t2). That is, the applied electric current EV during steady state is output. After that, Suinochiro 8. Ro9
When the switch 40 is turned off and the switch 40 is turned on (time L6),
Is the l-transistor Tr turned on? The charge in the capacitor C is discharged through the transformer/storer Tr and the resistor R3, and the voltage at the connection point A between the negative electrode side of the battery 37 and the resistor R3 becomes 1. (reverse polarity) is outputted via switch 40. Thereafter, as time passes, the discharge of the capacitor C ends and the discharge current no longer flows through the resistor R6, and the potential at point A becomes 0 (time t4).

As described above, the voltage shown in FIG. 7(a) is created.

However, in reality, the pulse waveform generated by charging and discharging the capacitor C changes exponentially, but if necessary, this can be made into a strict rectangular wave by using a waveform shaping circuit or the like.

Next, a description will be given of the light surrounding operation of the optical switch configured as follows and to which a voltage having the waveform shown in FIG. 7(a) is applied. If switches 38 and 39 are initially off,
Since no voltage is applied to the electrodes 15 and 16 from the power supply circuit 21, the cooling effect by the cooling body 18 is not performed and the first branch point 3
The temperature in the vicinity of 5 is the same as the ambient temperature Tm, and no warm distribution or refractive index distribution occurs. Therefore, the light C incident from the input optical fiber 62 is not deflected and passes through the main optical waveguide 29 to that extent.
The light propagates through the optical fiber 33 and is led out from the output optical fiber 33.

This state is the off state of the optical switch.

When the switches 38 and 39 are turned on, the power supply circuit 21 turns on the switches 39 and 39. Electrode 15.1 via lead wire 25.24
6, the cooling body 18 produces heat absorption at the electrode 17 due to the Peltier effect, absorbs the amount of heat from the branched optical waveguide 60 in close contact with the electrode 17, and causes a warm drop. Due to this temperature drop, the temperature distribution near the cooling body 18 becomes negative compared to the far part, and the refractive index becomes positive distribution. The temperature is lowest and the refractive index is highest at the center 7 in the width direction of the cooling body 18.
Near the end E1, the temperature gradient is the steepest and the refractive index gradient is also the largest. Therefore, when light passes near this i τj,
A dog of refractive index due to the presence of a refractive index gradient.

That is, the wavefront is tilted and deflected toward the center of the cooling body 18. Therefore, the input light C propagating through the input tongue main optical waveguide 29 from the input optical fiber 62 reaches the two-branch point 65.
The branched optical waveguide 6° is bent at the angle 6°, and the output light d is guided out from the output optical fiber 34. This state is the ON state of the optical switch.

In this case, when the switches 38 and 39 turn on at 9 o'clock, a +2V voltage is applied as described above, so the temperature drop is as shown in FIG. The slope is steeper than that in Figure 6 (BL).
Therefore, the optical power of the branch leading waveguide 6o is also as shown in FIG. 7(C).
As shown in the figure, the switch 38.39 rises at time t1 from the time t1 when it turns on, I'd3, and this delay time Td3 is 1t4JT when the optical power rises in the conventional branching waveguide.
d 1 2 vs. 1. Since 'i'c13-/2 to 15Td1 is extremely short, the response of the optical switch is improved. Since the applied voltage becomes +V after time t2 after the switches 38 and 39 are turned on.

The in-plane of the light beam settles at a deflection angle corresponding to this voltage, and the output light d is led out from the output optical fiber 54 as described above.

Further, when the switch 38.39r is turned off and the switch 40 is turned on, the applied voltage returns to the ground 1 circle Y quality T m at the 9 time point when the switch 38.39 turns off and branches as shown in FIG. 7(a). Although the temperature gradient near the point disappears.

Since the applied voltage is 1 m when the switches 8 and 39 are off and the switch 40 is on, the temperature return characteristic is more rapid than the conventional temperature return characteristic as shown in Fig. 7 (bl). Therefore, the optical power of the branched optical waveguide 60 also increases as shown in FIG.
As shown in (3), it falls at time Td4 from the time t6 when the switch 68°39 turns off.

Compared to the conventional delay time Td2 shown in Figure 6 (C), Td4 = /2~/3'rc12fxF),
Even when F4 is off, the response is rk-1r.

In addition, in the embodiment, a cooling body was used as the temperature gradient generating means 13'', but instead of this, a heating element was used.

Application: Negative and positive pulses may be superimposed on the steady applied voltage at the rise and fall of the pressure, respectively, and may be applied to the generator.

In addition, in the above example, the yt speed of the polymer film and the waveguide width are 50 μIn assuming all the switching of multimode light.
However, the optical switch of the present invention can also be used for single mode light by using this for 5 to 10 microns.

In the above embodiments, a molecular film was used as the material for the optical image wave path, but the optical switch of the present invention uses an amorphous material such as glass, or PLZ instead.
Polycrystalline materials such as T and ferroelectric materials such as LiNbO3 may all be used.

Figure 1 is a diagram showing a conventional optical switch, and Figure 2 is a side sectional view of the cooling body part used in the optical switch in which this optical switch is implemented. , FIG. 3 is a top view of the cooling body section.

FIG. 4 is a bottom view of the cooling body, and FIG. 5 is a reconnaissance diagram and a circuit diagram of an optical switch according to an embodiment of the present invention.

6 is a waveform diagram for explaining the switching operation of the conventional optical switch shown in FIG. 1, and FIG. 7 is a waveform diagram for explaining the switching operation of the optical switch of the first embodiment shown in FIG. FIG.

18: Cooling body, 21: Source circuit, 22: Switch circuit, 29: Main optical waveguide.

30 bifurcated optical waveguide, 3 optical waveguide.

55- Branching point.

Patent applicant: Tateishi 〒b゛, Koko Co., Ltd. agent
Patent Attorney Shigeru Nakamura Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] (1) An optical waveguide having a main optical waveguide and a branch leading waveguide,
A temperature gradient generating means provided in the vicinity of a branch point between the main optical waveguide and the branch leading waveguide of the leading waveguide, a switch circuit for turning on/off the operation of the temperature gradient generating means, and a switch circuit for turning on/off the operation of the temperature gradient generating means. In response, the temperature gradient generating means generates a voltage of the same polarity as the steady on voltage only at the time of turning on, and a predetermined voltage of the opposite polarity to the steady on voltage only at the time of turning off, through the switch circuit. An optical switch configured to turn on/off the temperature gradient generating means and a voltage source supplied to the optical waveguide to switch the direction of light propagation within the optical waveguide.