KR20000051571A - Optical switch composed of optical fiber - Google Patents

Abstract

PURPOSE: An optical switch is provided to produce the desired signals at the output ports, and minimize an optical loss of the optical fiber. CONSTITUTION: An optical switch comprises many optical fibers(51,52,53,54), two fiber-optic polarizers(61,71), two Faraday optical fibers(63,73), four polarization fibers(62,64,72,74), and a polarized light separating coupler(80). The input signal from each input ports is polarized by each fiber-optic polarizer, and the polarized signal is passed through each polarization fiber. Each Faraday optical fiber changes the polarization angle of signal by using direction of the magnetic field. Each polarization maintaining fiber produces signal rotated by predetermined angle. The polarized light separating coupler receives the signals generated from the polarization fibers, and each signal is simultaneously directed to a desired output port based on the polarization angle. An optical switch comprised of optical fibers provides easy alignment of the optical path, and reduces the optical loss.

Description

Optical switch composed of optical fiber

The present invention relates to an optical switch using an optical fiber that is capable of outputting an input optical signal to a desired output port, as well as reducing optical loss caused by the coupling between the devices constituting the optical switch.

Optical communication technology using optical fiber is mainly used for information communication between countries through submarine cable because it can transmit large amount of information at high speed and there is no signal interference or crosstalk caused by electromagnetic induction.

Recently, optical communication has been used as a backbone communication network for high-speed broadband multimedia communication including voice and data communication during the switching period and CATV (Cable TV) and VOD (Video On Demand) as the multiplexing technology and the network technology are advanced. It is gradually expanding.

Optical communication modulates light having different wavelengths generated from a plurality of laser diodes, and multiplexes an optical signal of multiple wavelengths using a multiplexer, and then transmits the multiplexed optical signals to a destination through a predetermined optical path. In the destination, the multiplexed optical signal is demultiplexed and separated into a plurality of optical signals having original wavelengths.

Meanwhile, the optical communication system multiplexes an optical signal of multiple wavelengths and transmits the multiplexed optical signal to the corresponding destination. Therefore, it is necessary to switch the optical signal to be transmitted to the corresponding destination in the process of transmitting the optical signal.

Therefore, currently known optical switches include a mechanical optical switch that adjusts the alignment state using a mechanical drive device, and a 90 degree change in the polarization state by using magneto-optical crystals, and a light path that is changed by using a polarization splitting device together. There is a magneto optical switch and an optical matrix switch for fabricating an optical waveguide using an electro-optic crystal such as Lithium Niobate (LiNbO 3) to adjust the coupling state between the waveguides.

1 is a view schematically showing the internal structure of a conventional magneto-optical switch.

In the drawings, reference numerals 1,2,3,4 denote first input optical fibers, second input optical fibers, first output optical fibers, and second output optical fibers, respectively, and 5,6,7, and 8 denote the input and output ports, respectively. The first to fourth lenses to be combined.

In addition, reference numeral 10 denotes a first prism coupled to the input optical fiber, and the reflecting plate 11 and the polarization separator 12 are provided as shown in FIG. 1 to be parallel to each other.

On the other hand, reference numeral 13 is a magnetic body portion for switching the polarity based on a predetermined input signal, 14 is to maintain or change the polarization state of the optical signal applied from the first prism 10 in accordance with the polarity of the magnetic body portion to output in one direction 20 is a second prism that separates an optical signal applied from the isolator 14 and switches it to a first output port and a second output port, and has a reflector plate (2) inside the second prism (20). 21 and the polarization separator 22 are provided as shown in FIG. 1 so that they are parallel to each other.

Next, the operation of the apparatus having the above-described configuration will be described by way of example.

In the state where the magnetic force component of the magnetic body portion 13 is set to 0 ° and the polarization component of the optical signal input to the isolator 14 is transmitted without being changed, the vertical polarization component from the first input port 1 ( When the optical signal A, which is combined with the horizontal polarization component ↔, is applied, the optical signal A is reflected on the inner surface of the first prism and applied to the polarization separator 12 according to the characteristics of the light. In the polarization splitter 12, the input optical signal A is separated and output according to the polarization component. The vertical polarization component (·) is reflected and the horizontal polarization component (↔) is transmitted. Therefore, the optical signal of the vertical polarization component (·) reflected by the polarization separator 12 is reflected by the reflecting plate 11 and applied to the second prism 20 through the isolator 14, and transmitted by the polarization separator 12. The optical signal of the horizontal polarization component ↔ is applied to the second prism 20 through the isolator 14.

On the other hand, the optical signal of the vertical polarization component (·) applied to the second prism 20 is output to the first output port 3 through the polarization separator 22, the horizontal polarization applied to the second prism 20 The optical signal of the component ↔ is reflected by the reflecting plate 21 and transmitted through the polarization separator 22, thereby being output to the first output port 3.

That is, the magneto-optic switch is capable of selectively outputting the optical signal applied to the second prism by applying a magnetic component to the optical signal output from the first prism to change the polarization component of the input optical signal. It is configured to switch a plurality of input optical signals to different output ports, such as the mechanical switch or the optical matrix switch described above.

For example, when the magnetic component applied to the isolator is 0 °, the signal applied from the first input port is output to the first output port, and the signal applied from the second input port is output to the second output port. When the magnetic component applied to the isolator is 90 °, the signal applied from the first input port is output to the second output port, and the signal applied from the second input port is output to the first output port.

However, in an optical communication system constituting a complex network, there may be a case where a plurality of input optical signals need to be transmitted to one output port. In this case, the above-described optical switch may not perform an operation accordingly. do.

In addition, the above-described optical switch is configured by combining a device configuration other than the optical fiber, the insertion loss of the input optical signal caused by passing through the device other than the optical fiber occurs, the intensity of the optical signal output from the output port of the optical switch The problem of attenuation occurs.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an optical switch using an optical fiber that can switch from different input ports to the same output port at the same time.

In addition, another object is to provide an optical switch using an optical fiber that is designed to reduce the optical loss generated by passing through the optical switch.

1 is a view for explaining the internal configuration of a general magneto optical switch.

2 is a view showing the internal configuration of an optical switch using an optical fiber according to the first embodiment of the present invention.

3 is a view for explaining the operation of the optical switch using the optical fiber shown in FIG.

*** Explanation of symbols for the main parts of the drawing ***

51,52,53,54: optical path, 61,71: optical fiber polarizer,

62,64,72,74: polarization maintaining optical fiber, 63,73: Faraday optical fiber,

80: polarization split coupler.

The optical switch using the optical fiber according to the present invention for achieving the above object is an optical polarizer for converting the polarization of the optical signal applied from the input port to a polarization in a predetermined direction and outputs the optical signal input from the optical fiber polarizer Faraday optical fiber for changing and outputting the polarization angle according to the direction of the magnetic field applied by the polarization, Polarization maintaining optical fiber for outputting by rotating the polarization state of the optical signal input from the Faraday optical fiber according to the alignment direction of the polarization axis at a predetermined angle, and the polarization And a polarization split coupler for outputting the optical signal input to the corresponding output port based on the polarization angle of the optical signal applied from the holding optical fiber.

According to the present invention having the above-described configuration, it is possible to output the input optical signal to the desired output port, as well as by configuring the device to the optical fiber to facilitate the mechanical alignment to match the optical path consequently coupling between the devices It is possible to reduce the light loss caused by.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

In FIG. 2, when an optical signal is applied through the first optical path 51, the optical signal is applied to the first optical fiber polarizer 61 to convert light of an arbitrary polarization state of the input optical signal into light of a constant vertical polarization. Will be output.

In addition, the vertical polarization signal output from the first optical fiber polarizer 61 is applied to the first Faraday optical fiber 63 while maintaining the polarization state through the polarization maintaining optical fiber 62, wherein the Faraday optical fiber ( When the magnetic field is applied from the outside, the role 63 rotates the polarization state of the light traveling in a predetermined direction according to the direction of the applied magnetic field.

On the other hand, the vertical polarization signal applied to the first Faraday optical fiber 63 is rotated 45 degrees forward / reverse in accordance with the direction of the external magnetic field to maintain the polarization state of the optical signal through the second polarization maintaining optical fiber 64 polarization split coupler Is applied to the first input of 80.

Here, the second polarization maintaining optical fiber 64 is configured to rotate by 45 ° clockwise to output the polarization of the input optical signal.

On the other hand, the second optical signal applied through the third optical line 53 is applied to the second optical fiber polarizer 71 to convert the arbitrary polarization state of the second input optical signal into a vertical polarization state and output.

The vertical polarization signal output from the second optical fiber polarizer 71 is applied to the second Faraday optical fiber 73 while maintaining the vertical polarization state through the third polarization holding optical fiber 72.

The vertically polarized signal applied to the second Faraday optical fiber 73 is rotated 45 DEG / reverse in the direction of the external magnetic field to maintain the polarization state of the optical signal through the fourth polarization maintaining optical fiber 74 and the polarization splitting coupler 80 Is applied as the second input.

Here, the fourth polarization maintaining optical fiber 74 is configured to rotate the polarization of the input optical signal by 45 degrees clockwise to output.

On the other hand, the first input optical signal and the second input optical signal applied to the polarization split coupler 80 is output to the first output port through the second optical line or the second through the fourth optical line according to the polarization component It will be output to the output port.

Next, with reference to Figure 3 will be described the operation of the optical fiber optical switch according to an embodiment of the present invention.

Here, the polarization state of the light shown in FIG. 3 is shown on the basis of the cross section perpendicular to the optical fiber. In the drawing, (X) indicates that the direction of the magnetic field applied to the Faraday optical fibers 62 and 72 is "↓". It is for explaining the operation process, and (Y) is for explaining the operation process when the direction of the magnetic field applied to the Faraday optical fibers (62, 72) is "↑".

First, when the direction of the magnetic field affecting the Faraday optical fibers 62 and 72 in the figure is "↓", if the polarization state of the input optical signal applied through the first optical path 51 is "X1", the input The optical signal passes through the first optical fiber polarizer 61 and is converted into a vertical polarization state in a predetermined direction such as "X2".

Subsequently, the optical signal whose polarization state is changed to the vertical polarization state such as "X2" is applied to the first Faraday optical fiber 62 in the vertical polarization state (in the form of "X2"). During the passage, the polarized light of the optical signal is rotated by 45 ° clockwise to be output in the form of "X3".

Thereafter, the optical signal output in the form of "X3" through the first Faraday optical fiber 62 is applied as an input signal of the polarization split coupler 80 through the polarization maintaining optical fiber 64, wherein the optical signal is While passing through the polarization maintaining optical fiber 64 is rotated by 45 ° clockwise polarization is applied to the polarization separation coupler 80 in a polarized form of "X4", that is, a horizontal polarization state.

Therefore, when output through the polarization separation coupler 80 is output to the first output port through the second optical path (52).

In addition, when the second input optical signal is applied through the third optical line 53, the second input optical signal is output to the second output port through the fourth optical line 54 under the above condition.

On the other hand, when the direction of the magnetic field affecting the Faraday optical fibers 62 and 72 in the figure is "↑", if the polarization state of the input optical signal applied through the first optical path 51 is "Y1", this input The optical signal passes through the first optical fiber polarizer 61 and is converted into a vertically polarized state in a predetermined direction such as "Y2".

Subsequently, the changed optical signal such as "Y2" is applied to the first Faraday optical fiber 62 in the form of "Y2", so that the polarization of the optical signal is counterclockwise while passing through the first Faraday optical fiber 62. The polarized light rotates by 45˚ and is output in the form of "Y3".

Thereafter, the optical signal output in the form of "Y3" through the first Faraday optical fiber 62 is applied as an input signal of the polarization split coupler 80 through the polarization maintaining optical fiber 64, wherein the optical signal is While passing through the polarization maintaining optical fiber 64 is rotated by 45 ° clockwise polarization is applied to the polarization separation coupler 80 in a polarized form of "Y4", that is, a vertically polarized state.

Therefore, when output through the polarization separation coupler 80 is output to the second output port through the fourth optical line (54).

In addition, when the second input optical signal is applied through the third optical line 53, the second input optical signal is output to the first output port through the second optical line 52 under the above condition.

That is, according to the above, when the magnetic fields of the first Faraday optical fiber and the second Faraday optical fiber are set to be the same, when the polarization state of the optical signal input to the polarization splitting coupler 80 is the horizontally polarized state, When the input signal is output to the first output port, the second input signal to the second output port, respectively, and the polarization state of the optical signal input to the polarization split coupler 80 is a vertical polarization state, the first input signal The second output signal is output to the second output port, respectively.

In addition, when the directions of the magnetic fields of the first Faraday optical fiber and the second Faraday optical fiber are set opposite to each other, all input signals are output to one output port.

For example, when a magnetic field is applied to the first Faraday optical fiber in the "↑" direction and a magnetic field is applied to the second Faraday optical fiber in the "↓" direction, the optical signals applied to the first input port and the second input port are both made of the first Faraday optical fiber. It is output through 2 output ports.

Therefore, in the above configuration, it is possible not only to output the input optical signal to a desired output port, but also to configure the devices by optical fibers, so that the mechanical alignment for the optical path is easy, resulting in the coupling between the devices. It is possible to reduce the light loss.

On the other hand, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the technical spirit of the present invention.

That is, in the above embodiment, when the polarization state of the optical signal input to the polarization split coupler is horizontally polarized, and is output as it is, and in the case of vertical polarization, it is output to cross, but the polarization axis alignment direction of the polarization maintaining optical fiber In contrast to the embodiment, it can be configured to be output in the case of horizontally polarized light, and to be output as it is in the case of vertically polarized light.

As described above, according to the present invention, it is possible not only to output the input optical signal to a desired output port, but also by configuring the devices with optical fibers, so that the mechanical alignment for matching the optical path is easy, and consequently, It is possible to reduce the light loss caused by.

Claims (3)

An optical fiber polarizer for converting the polarized light of the optical signal applied from the input port into polarized light in a predetermined direction and outputting the polarized light; Faraday optical fiber for outputting the optical signal input from the optical fiber polarizer by changing the polarization angle according to the direction of the magnetic field applied from the outside, A polarization-maintaining optical fiber for outputting by rotating a polarization state of an optical signal input from the Faraday optical fiber at a predetermined angle according to the alignment direction of the polarization axis; And a polarization split coupler configured to output an optical signal input to the corresponding output port based on the polarization angle of the optical signal applied from the polarization maintaining optical fiber. The method of claim 1, The polarization split coupler is configured to output to the output port corresponding to the input port when the input optical signal is horizontally polarized, and to the output port configured to cross when the polarized light is vertically polarized. The method of claim 1, And at least two input ports, and configured to apply the magnetic field independently for each Faraday optical fiber coupled to each input port.