JPS5883801A - Optical switch - Google Patents

Abstract

PURPOSE:To reduce the optical insertion loss of an element, by providing a lens, which allows optical axes of optical beams transmitted through a lateral optical converter to cross on the focal plane, and a crystal plate which makes optical beams transmitted through the lens incident to the position of crossing of optical axes at a Brewster angle. CONSTITUTION:The light emitted from an incidence optical fiber 1 is converted to a parallel luminous flux 12 through a collimator lens 2 and is incident to a polarizer 3 and is separated to a P wave 14 and an S wave 13. A lens 4 is so provided that its focus position is the reflection position on the polarizer 3. A high NA value, for example, about 0.5NA value is given to the lens 4, and the angle formed by the P wave 14 and the S wave 13 emitted from the polarizer 3 is narrow and about 32 deg., and therefore, both optical axes are made parallel by the lens which has a high NA value and has the focus position arranged in said reflection position, and the P wave 14 and the S wave 13 become a P polarized light 16 and an S polarized light 15. The beam diameter isn the rear focus position of the lens 4 is reduced to a value obtained by multiplying the magnification of the ratio of focal length of the lens 2 to the lens 4 by the value of the beam diameter on the exit end face of the optical fiber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical 7-eye pass switch that changes the optical pulses transmitted through a fiber, and
A. Regarding electronic optical switches.

In the Hikari 7 taper overconfucian system, in order to increase vA1110 reliability and ease maintenance, regular and spare
Optical switches are widely used for switching optical components during switching of in, and for measurement. A data transmission system that connects intelligence equipment within a limited area.

- on the so-called optical data highway. Optical switches are used for highways, terminals, and OII connections. That is, when it is necessary to avoid 41 fixed terminals, 9, for example terminal failure, maintenance inspection.

When not in use, use an optical switch to bypass the route.

One of the optical switches that have been developed to meet the abovementioned purposes is one that electromagnetically displaces the ζ-ra during the blizzard. That is, by converting the light emitted from the optical system into a parallel beam and inserting a prism into the optical path, the beam is spatially condensed,
This is to select the light 7 eyeper to be focused again. ζO
Although this type of optical switch has the characteristics of high crosstalk and low optical insertion loss and is easy to use, it is difficult to obtain a high switching speed because it has a mechanical movable mechanism. For example, there are concerns about reliability for operations with long intervals.

There is instability in that the switch almost uniquely maintains a certain state for a long period of time, and when a switch operation is suddenly performed, the switch does not operate correctly. Therefore, it cannot be used in optical submarine repeaters, etc., where it is difficult to easily replace or inspect elements.
It is.

There is also known an element that electronically switches fiber light without having a mechanically movable part, such as that of Shaji O. The incident light passes through nine light conversion elements that have the function of changing the polarization direction of the transmitted light by applying a voltage to 9F1 by applying a round wire current, and after ζO, it passes through a polarizing element that changes the polarization direction depending on the polarization direction of the light. It guides light to different optical aipaths depending on the direction of the light. As the polarization conversion element, electro-optic materials such as electro-optic crystals and liquid crystals, magneto-optic materials such as iron garnate crystal, medium-high polarization glass, and the like are used. Conventional optical switches of this type have several drawbacks. Two companies.

The problem is that the constituent polarizing elements are expensive or have insufficient characteristics. As mentioned above, polarizing elements that change the polarization depending on the polarization direction of the light include polarizing prisms made of calcite, which is a material with high birefringence that has been known for a long time.
The inside is made of rutile crystal, which is a material with a large double refraction, formed into a prism shape and polished, and is made of glass.A three-layer film of Kll electric material is formed on the reflective surface of the total reflection prism, and a polarizing element is formed. There are things to do. Calcite is a natural stone and is expensive, and rutile prism is also an expensive crystal material, and like 4M, it has a high refractive index, and it is necessary to form a good anti-reflection film for the prism incident image. In polarizing elements made of glass material with a dielectric multilayer film, the wavelength characteristics of the multilayer film are sensitive to incident light, so there are drawbacks such as deterioration of the polarization characteristics when light of a wavelength deviates from the design wavelength is incident. have

Also, the one point 25@ of a conventional optical switch is.

The applied external field O may require a large light transmission capacity of the polarization conversion element or may require a cylindrical lens.
It is difficult to avoid an increase in light transmission loss due to large or circular lens O aberrations.

In other words, the arrangement of the optical system includes a collimating lens that directs the light beam to the input beam by y1 meters, and a Kento lens that collects the beam to the output beam 1, and the optical path of these lenses is The above-mentioned polarization conversion element and polarization element are provided. The rounded value light conversion element eIIf requires a number of angles or a number of angles or more. This rounded polarization conversion element uses magneto-optical material.
In the case of the A circle, when the demagnetizing field coefficient is large, the external magnetic field that is applied to saturate the &L magnetization is large, and the round electromagnetic field that generates this magnetic field is also large. % using electro-optic materials
/%Marubasha uses an sIAIIIm element with a small electro-optical effect O.If the applied voltage is several hundred V and a high-0 polarization conversion element is used in the form of a plate, the demagnetizing field coefficient O Declining horizontally■
This can be achieved by using an electro-optical element. 10 good: 11 meters) Cylindrical lenses that reduce the beam of light in one dimension are provided before and after the polarization conversion element. High-performance cylindrical lenses with several OS point distances have particularly large aberrations, which worsens the element's initial insertion loss.

The object of the present invention is to eliminate the above point and provide a 7-eye light switch.

According to the present invention, both INK optical polishers having a high refractive index are passed through a crystal plate, and the light beam is incident on the crystal plate at a pre-star angle, passes through the crystal plate, and is reflected from the optical axis of the electric beam. a lens that parallelizes the optical axis of the traveling light beam, and a polarization conversion element that transmits the two light beams that are parallelized by the lens and rotates the polarized light beam by an applied external field. .

#
Let the light beam pass through the lens and enter at Brewster's angle L
An inexpensive and high-performance optical switch can be obtained by using the same crystal plates as the above-mentioned crystal plates arranged in such a manner as to be similar to the above-mentioned crystal plates.

Polarizing filters have been known since ancient times that improve the aSS polarization degree of transmitted light by making light incident on a high refractive index O crystal plate such as a silicon crystal at the Brewster's angle. However, in ζhi, the light reflected by the polarizing filter is not used, but the transmitted light and reflected light by the crystal plate with a high refractive index are optically xmi
A simple construction for condensing light and an industrially advantageous optical switch configuration combining an optical system and a polarization converting element were first realized through actual research.

Details of the actual W140 will be further explained using examples.

Fig. 1 shows the present example, 1 is the incident light 7 eyeper, 2 is the lens, 3 is the incident side O area light element, 4
．． 6 is a condenser lens, and S is a polarization conversion element.

7 is a polarizing element on the output side, 8.9d is a collection lens, 1 to l
1 is an output optical fiber. The forward light emitted from the input optical fiber 1 is transferred to the parallel forward wheels 12 and 1 by the remating lens 2, and is incident on the polarizer 3. The principle of the polarizer 30 will be described later, but its function is that the incident light is 12t! '11114 and 8m1
Separated into 3, 54kh, V's 4B sea urchin is strange. The lens is a lens having a high NA value, for example, an OSS value. Since the angle formed by the P wave 14fl wave 13 emitted from the polarizer 3 is as narrow as 32 degrees and Il angle as mentioned in the discussion, their optical axes are parallel to each other by the lens 4 having a high N value and having the focal position arrangement. The P-polarized light becomes 16.8 and the P-polarized light becomes 15. The beam diameter at the rear focal position of the lens 40 is focused to 9 by multiplying the beam diameter at the exit end surface of the light 7 eyeper 1 by the magnification ratio of the focal length ratio of the lenses 2 and 4. For example, if you choose the optical fiber 4/(for IK with a diameter of 50-) and the focal lengths of lenses 2 and 4 to be equal, the image will be 6 equal magnification, so the light beam diameter at the iuw focal position of lens 4 will be 50 am and 11 degrees.Therefore, the ring in the direction perpendicular to the paper in FIG. The two linearly polarized lights 15° and 16 incident on the polarization converter 5 change their polarization state depending on the state of the external field such as voltage or current applied to the polarization converter. The polarization state is determined to be polarized light orthogonal to that.

Now, the polarization converter 5 K J 5 inverts the polarization by 91'11, and if it is 9, then the incident polarized light IS becomes r polarized light and P polarized light 1.
6 is polarized into 8 polarized light and outputted from the polarization conversion element 5. The lens 6 (output polarizer) through which these front plates pass is the lens 4. Assuming that the input polarizer is 3 and Oka-0% respectively,
The lenses □ are arranged symmetrically across the 4011 point positions. That is, one of the focal positions of the lens 6 is the lens 40.
The focal position is the focal point, and the other is the polarizer 70 light reflection position. The optical axes of the two polarized lights d passing through the lens 6 are converged at the focal point of the lens 60, and each light beam becomes a parallel leading wheel.

As mentioned above, lens 6 is a lens with the same 0411 characteristics as lens 4. The angle of collection of the optical axes of the two polarized lights 17 and 18 is changed so that the two polarized lights 13 exit the incident polarizer 3 and head towards the lens 4. It is the same as the angle formed by .14. As described above, the light beam 15, which is 8-polarized light, is a rounded light beam that has undergone polarization conversion, and the light beam 15 is P-polarized light. A light beam 17 which is incident on the output polarizer 7 and is 9r polarized light is transmitted through the polarizer 7 and becomes a light beam 20, which is coupled to the output fiber IIK via the lens 9.

When the light beam 16, which is previously P-polarized, undergoes polarization conversion, it becomes 8
The polarized light beam 18 is reflected by the polarizer 7, merges with the previous light beam 20, and is delivered to the output fiber IIK. That is, the beam emitted from the optical fiber /(1 is polarized and separated by the polarizer 3, polarized by the polarization converter 5, polarized by the polarizer 7 on the output side, and sent to the output fiber 11. On the other hand, if the state of the external field such as the voltage and current applied to the polarization converter 5 is set so that rotation of polarization does not occur, the above-mentioned light beam 17 becomes the light beam 1.
This light beam is reflected by the polarizer 7 and becomes a light beam 19 that passes through the lens 8.
A separate light beam IOK from 11 is coupled via. Furthermore, since the light beam 18 is P-polarized light, it passes through the polarizer 7,
It merges with the previous light beam 19 and is finally delivered to the optical fiber 10. In this case, the destination from which the optical fiber 1 is emitted is
The money is sent to the output optical fiber 10. That is, by switching the shape of the polarization converter IIO, the tip of the optical fiber 10 can be coupled to either of the two output optical fibers 1619 or 11. ×2 light switch? Oj's work is realized.

Next, sharpen the operation of the polarizer O. The second diagram is a diagram showing the principle of a polarizer.

Indicumlin etc. o@IA single crystal plate''eh. These crystals are very transparent crystals with a light wavelength of 1 m to 2 μm. For example, N!Of/l:y The light wavelength of Yaria density 1.4X10aw is 1.3J.
The absorption coefficient in the 1m-1 Jim() area is 6.1 as-
``The refractive index is very high at 3.5 degrees, and the star angle is 74 degrees, which means that the light beam 101 can be converted to a diameter of 74 degrees (the proverbial θ). When the light is incident at a puda crystal star angle of 16 degrees), oxm is added on the top and bottom surfaces of the thin crystal plate, and the 0 reflected light 102 has 8 polarized components.Sand and 1-)
Its reflectance is 84 times. What about Haruka Hikari 10B? Most of the polarized light components are present, and the O transmittance is as described above, and the 8 polarization potential encountered by the very high-0 rays of the far-field light 103 is 13 arcs. A happy two-photon element is obtained. As mentioned before, since the light beam must be incident at a very narrow angle of 0116 degrees, by using a lens with a high KNA value as shown in No. 111, the optical axis of the P-polarized light can be changed. Can be parallelized.

For the polarization converter 5, various conventionally known ones are used.For example, LITa01 is used.
The electro-optic effect of a crystal can be used as a polarization converter.If a magneto-optic crystal such as YIG is used, the polarization converter can be used as described above. Since the light beam diameter is very small at 50 am,
%/h deviation also requires a thin crystal plate, and the applied voltage and applied magnetic field strength are low.

1st cabinet K > If one person uses fiber optic, either one of the two O
An example of a loose 1 x 2 optical switch coupled to the output fiber will be shown. A 2 x 2 destination switch will be realized by using two optical 7-eyepers on the input side and arranging them in the same way as the output fiber in Yuki 111. That's a matter of fact.

In addition, the lens that parallelizes the optical axes of the 8 damaged light beams P light beams O emitted from the polarizing element can perform the same function with just one lens! In this case, two lenses may be used, one at a time. It is possible to do the same thing with a polarizing element and a lens.

As described above, according to the present invention, an inexpensive and high-performance optical switch can be obtained.

[Brief explanation of the drawing]

The 1st m is a diagram showing the configuration of an embodiment of the present invention, where 1 is an input optical fiber, 3 is an input side polarizing element, 4 and 6 are thin beams with a high N value, 5 is a catfish polarization conversion element, and 5) discharge. power side polarizing element,
10.11 is the output light 7 eyeper. This is an original ll1l″t″1OQd high refractive index crystal plate showing the operation of the 2nd IIl catfish polarizing element. Peng 1 Figure Pigeon 2 Figure 03

Claims (1)

[Claims] The crystal plate has a high refractive index and has been optically polished.The optical axis of the light beam that is incident on the crystal plate at Brewster's angle and passes through the crystal plate is reflected. a lens that parallelizes the axis, and a one-light conversion element that allows the optical beam parallelized by the lens to pass through and make the optical beam distorted by 90 degrees by an applied external field. Then, a lens that passes through the wrinkled tip conversion element and causes the optical axes of the light beam to intersect on the focal image, and a light beam that has passed through the shank lens at the position where the optical axes intersect and cross is placed at the Brewster angle. , a tip switch that has a Zengki Noodle crystal plate and an Oka-〇 crystal plate arranged so as to emit light from the bottom.