KR102128201B1 - Differential polarization Shift Keying based Optical Transmitter/Receiver and Method thereof - Google Patents

Abstract

The present invention may provide an optical transmission and reception apparatus and a method thereof which may generate converted data having values in which x and y elements are respectively variable in response to input data applied from initial converted data having a predetermined initial value, transmit a transmission polarization signal by modulating the intensity of X polarization and Y polarization respectively according to the converted data, and accurately acquire restoration data corresponding to the input data according to the change of reception converted data having x and y elements obtained by detecting the light intensity of the X polarization and Y polarization of a reception polarization signal applied through an optical line.

Description

Differential polarization shift keying based optical transmitter/receiver and method thereof

The present invention relates to an optical transmitting and receiving device and method, and to a differential polarization transition based optical transmitting and receiving device and method.

Among the existing optical communication systems, the direct detection (DD) system modulates and transmits the intensity of an optical signal, and detects the intensity of the received optical signal to demodulate the signal, and mainly employs an intensity modulation (IM) technique. Although used, a polarization shift keying (PSK) modulation technique that modulates by shifting and modulating a polarization state, which is one of the main characteristics of a light source, has recently attracted attention.

In the direct detection system using the intensity modulation technique, the receiver detects only the intensity of the received optical signal, while using the polarization shift modulation technique has the advantage of using polarization diversity.

However, when a signal modulated by a polarization transition is transmitted through a single mode optical fiber, the polarization state of the optical signal due to the transmission distance of the optical fiber or the physical change factor of the optical fiber (change in temperature, vibration, external bending, etc.) of Polarization: SOP). Accordingly, there is a problem that a structure for demodulating a received signal is complicated because a complicated polarization state maintaining device or a tracking technique is required.

A differential polarization shift keying modulation transmission/reception system that modulates only the change in polarization state of two adjacent symbols in consideration of the change in polarization state has been proposed, but the structure of the structure for demodulating the received signal is high and a delay element is used. As the optical interferometer is demodulated, it is difficult to accurately match the phase difference between the wavering and the interfering paths in the interferometer.

Korean Patent Publication No. 10-2006-0114315 (released on Nov. 2006)

An object of the present invention is to provide a differential polarization transition based optical transmission and reception device and method that can demodulate a signal with low complexity by not requiring a polarization state maintaining/tracking device.

Differential polarization transition-based optical transmission device according to an embodiment of the present invention for achieving the above object is a polarization distributor for distributing the light emitted from the light source to X polarization and Y polarization in the vertical direction of each other; A data converter configured to obtain transformed data by varying x elements and y elements of previously obtained transformed data according to input data; A modulator for adjusting the light intensity of each of the X polarization and the Y polarization according to the x and y elements of the converted data; And a polarization combiner that combines X-polarized light and Y-polarized light to obtain a transmitted polarization signal. It includes.

The data conversion unit converts the data previously obtained (E _n-1) and input data (D _n) converting data (E _n) based on the equation

이고, θ는 입력 데이터(D_n)에 대응하는 편광 회전 각도로서, 입력 데이터의 값(D_n)이 "1"이면 이전 변환 데이터(E_n-1)의 편광 각도로부터 π/2 회전(SOP + π/2)하고, "0"이면 -π/2회전(SOP - π/2)한다.)에 따라 획득할 수 있다.(Where M _θ is a state conversion function for converting the X polarization (X) and Y polarization (Y) of the previous transform data (E _n-1 ) according to the input data (D _n ).

, And θ is a polarization rotation angle corresponding to the input data D _n , and if the value D _n of the input data is “1”, π/2 rotation (SOP) from the polarization angle of the previous conversion data E _n-1 + π/2), and if it is "0", it can be obtained according to -π/2 rotation (SOP-π/2).

The data conversion unit may be set in advance such that x elements and y elements of the initial conversion data E ₀ have different predetermined initial values.

An optical receiving apparatus according to another embodiment of the present invention for achieving the above object is a linear polarization regulator for extracting linear polarization by filtering the circular polarized light and elliptical polarized light from the received polarization signal applied through the optical line; A polarization divider for distributing the linearly polarized light extracted from the linearly polarized light regulator into a predetermined X-axis direction X polarization and a Y-axis direction Y polarization; A light detection unit that detects the light intensity of each of the X polarization and the Y polarization and obtains an X polarization value and a Y polarization value; And receiving transformed data having x and y elements corresponding to the X polarized value and the Y polarized value, and transmitted by the optical transmission apparatus by using changes in the x and y elements of the received transformed data successively. A data restoration unit to restore one input data; It includes.

The data restoration unit may express the received transform data having x elements and y elements in a complex number form, and obtain the input data according to a phase change between previous received transform data expressed in a complex number form and current received transform data. .

The data restoration unit is a mathematical expression from the initially determined number of received transform data (RE ₀ , RE ₁ , RE ₂ ) and pre-stored pilot transform data (E ₀ , E ₁ ) among the received transform data continuously acquired.

(Where R(t _n ) represents the change in polarization state that occurs while the previous conversion data (E _n-1 ) and the conversion data (E _n ) are applied, and R(t _n-1 ) ≒ R(t _n ) .) to obtain the conversion data (E ₂ , E ₃ , ..., E _N ) afterwards, and the input data from the change of the obtained conversion data (E ₂ , E ₃ , ..., E _N ) Can be restored.

Differential polarization transition based light transmission method according to another embodiment of the present invention for achieving the above object comprises the steps of distributing the polarized light emitted from the light source to X polarization and Y polarization in the vertical direction to each other; Obtaining transformed data by varying x and y elements of previously obtained transformed data according to input data; Adjusting light intensity of each of the X polarization and the Y polarization according to the x element and the y element of the converted data; And combining the X-polarized light and the Y-polarized light intensity to obtain a transmission polarization signal, and transmitting the obtained transmission polarization signal through an optical path; It includes.

A light receiving method according to another embodiment of the present invention for achieving the above object comprises the steps of extracting linearly polarized light by filtering circularly polarized light and elliptical polarized light from a received polarization signal applied through an optical line; Distributing the extracted linearly polarized light into a predetermined X-axis direction X polarization and a Y-axis direction Y polarization; Detecting the light intensity of each of the X polarization and the Y polarization to obtain an X polarization value and a Y polarization value; And receiving transformed data having x and y elements corresponding to the X polarized value and the Y polarized value, and transmitted by the optical transmission apparatus by using changes in the x and y elements of the received transformed data successively. Restoring one input data; It includes.

Therefore, the optical transmission/reception apparatus and method according to an embodiment of the present invention generates and converts differential polarization modulation to transmit polarization signals by generating and converting differential polarization modulation data corresponding to input data applied from initial transform data having a predetermined initial value. Transmitting and detecting the light intensity of the X polarization and the Y polarization of the received polarization signal applied through the optical line, it is possible to accurately obtain the input data according to the change of the received conversion data. Since the reconstructed data is obtained according to the change of the received conversion data, the influence on the change in the polarization state by the optical line can be neglected, so that no separate configuration for differential demodulation or maintaining/tracking the polarization state is required. Therefore, the signal can be demodulated with low complexity, and input data can be quickly and accurately restored without using a delay element.

1 shows a schematic structure of an optical transmission/reception system according to an embodiment of the present invention.
FIG. 2 shows an example of conversion data obtained according to input data in the data conversion unit of FIG. 1.
3 shows a detailed configuration of the modulator of FIG. 1.
FIG. 4 illustrates a concept in which the data restoration unit of FIG. 1 acquires restoration data.
5 shows an optical transmission/reception method according to an embodiment of the present invention.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the contents described in the accompanying drawings, which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and is not limited to the described embodiments. And, in order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals in the drawings indicate the same members.

Throughout the specification, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated. In addition, terms such as "... unit", "... group", "module", and "block" described in the specification mean a unit that processes at least one function or operation, which is hardware or software or hardware. And software.

1 shows a schematic structure of an optical transmission/reception system according to an embodiment of the present invention, FIG. 2 shows an example of conversion data obtained according to input data in the data conversion unit of FIG. 1, and FIG. 3 shows modulation of FIG. 1 The detailed structure of the part is shown. And FIG. 4 shows the concept of the data restoration unit of FIG. 1 obtaining the restoration data.

Referring to FIG. 1, the optical transmission/reception system of the present embodiment includes an optical transmission device 100 and an optical reception device 200.

The optical transmission device 100 includes a light source 110, a polarization divider 120, a data conversion unit 130, a first modulation unit 140, a second modulation unit 150, and a polarization combiner 160.

The light source 110 generates and emits light in a continuous wave (CW) mode with a predetermined wavelength and waveform. The light source 110 may be embodied as, for example, a laser diode.

The polarization divider 120 receives the light emitted from the light source 110 and separates it into two linearly polarized light whose vibration direction of the electric field vector (or magnetic field vector) is fixed in a designated direction. Here, the two linearly polarized electric field vectors (or magnetic field vectors) are fixed in a direction perpendicular to each other (90 degrees). For convenience of description, in this embodiment, one of the two linearly polarized light is distributed as X polarization (X) in the X-axis direction, and the other one is distributed as X polarization (Y) in the Y-axis direction perpendicular to the X polarization (X). I assume. The polarization divider 120 outputs the separated two linearly polarized light to the first modulator 140 and the second modulator 150, respectively.

The data converter 130 receives the input data (D = {D ₁ , D ₂ , D ₃ , ... D _N }) of N bits (where N is a natural number) to be transmitted, and the input data ( D) is converted in a predetermined manner to output converted data (E). The data conversion unit 130 subsequently converts the conversion data E ₁ , E ₂ , E ₃ , ... E _N according to the input data D applied from the initial conversion data E ₀ having a predetermined matrix value. To acquire.

)로 획득될 수 있으며, 일예로 초기 변환 데이터(E₀)의 두 개의 원소(E_x0, E_y0)는 서로 다른 값의 초기값(A, 0)(

)을 가질 수 있다. 이는 변환 데이터(E₁, E₂, E₃,... E_N)가 차등 편광 천이 변조 기법에 용이하게 적용될 수 있도록 하기 위함으로, x 원소(E_x0)는 X 편광(X)에 대응하고, y 원소(E_y0)는 Y 편광(Y)에 대응한다.The transform data (E) is a matrix form of 2 rows and 1 column to correspond to X polarization (X) and Y polarization (Y), respectively.

), for example, two elements (E _x0 , E _y0 ) of the initial transform data (E ₀ ) are different initial values (A, 0) (

). This is because the transform data (E ₁ , E ₂ , E ₃ ,... E _N ) can be easily applied to the differential polarization transition modulation technique, where the x element (E _x0 ) corresponds to X polarization (X) , y element (E _y0 ) corresponds to Y polarization (Y).

As described above, the X polarization (X) and the Y polarization (Y) are polarizations perpendicular to each other, and the data conversion unit 130 applies previously obtained conversion data (E ₀ , E ₁ , E ₂ , ... E _N-1 ) and conversion data for converting the polarization state (SOP) of the conversion data (E ₁ , E ₂ , E ₃ , ... E _N ) based on the input data (D) according to Equation 1 To acquire.

이고, θ는 입력 데이터(D_n)에 대응하는 편광 회전 각도로서, 입력 데이터의 값(D_n)이 "1"이면 이전 변환 데이터(E_n-1)의 편광 각도로부터 π/2 회전(SOP + π/2)하고, "0"이면 -π/2회전(SOP - π/2)한다.Here, M _θ is a state conversion function for converting X polarization (X) and Y polarization (Y) of the previous transform data (E _n-1 ) according to the input data (D _n ).

, And θ is a polarization rotation angle corresponding to the input data D _n , and if the value D _n of the input data is “1”, π/2 rotation (SOP) from the polarization angle of the previous conversion data E _n-1 + π/2), and if "0", -π/2 rotation (SOP-π/2).

이고, 입력 데이터(D₁)의 값이 "1"이면, 변환 데이터(E₁)는

로 획득되는 반면, 입력 데이터(D₁)의 값이 "0"이면, 변환 데이터(E₁)는

로 획득될 수 있다. 그리고 동일한 방식으로 수학식 1에 따라 이후 변환 데이터(E₂, E₃, E₄, ... E_N)가 이후 입력 데이터(D₂, D₃, D₄, ... D_N)에 따라 획득될 수 있다.For example, the initial conversion data (E ₀ )

, And if the value of the input data D ₁ is "1", the conversion data E ₁ is

On the other hand, if the value of the input data D ₁ is "0", the converted data E ₁ is

Can be obtained with And in the same way, the subsequent transformed data (E ₂ , E ₃ , E ₄ , ... E _N ) according to Equation 1 is subsequently used according to the input data (D ₂ , D ₃ , D ₄ , ... D _N ) Can be obtained.

FIG. 2 shows an example of conversion data obtained according to input data in the data conversion unit of FIG. 1.

인 것으로 가정하고, 입력 데이터(D)는 "1011"의 4비트 값을 가지는 것으로 가정한다. 이 경우, 변환데이터(E₀, E₁, E₂, E₃, E₄)는 도 2에서와 같이

로 획득된다.Here, the initial conversion data E ₀ is as described above.

It is assumed that the input data D has a 4-bit value of "1011". In this case, the conversion data (E ₀ , E ₁ , E ₂ , E ₃ , E ₄ ) is as shown in FIG. 2.

Is obtained by

The first modulator 140 and the second modulator 150 constitute a modulator and receive corresponding polarization among X polarization X and Y polarization Y distributed from the polarization divider 120, respectively. Then, the data conversion unit 130 receives the corresponding elements (E _x , E _y ) of the converted data (E) converted according to the input data (D), and responds according to the applied elements (E _x , E _y ) The light intensity of X polarization (X) and Y polarization (Y) is adjusted and output.

Referring to FIG. 3 in detail, the first modulator 140 includes a light intensity modulator 142 disposed between two polarization adjusters 141 and 143 and two polarization adjusters 141 and 143. . The first polarization controller 141 among the two polarization controllers 141 and 143 receives the X polarization X distributed by the polarization distributor 120, and the X-axis direction of the X polarization X is precisely possible. Adjust as much as possible. Although the polarization divider 120 distributes and transmits the light provided from the light source 110 in the X-axis direction and the Y-axis direction in the X polarization (X) and the Y polarization (Y), the light intensity modulator 124 is input Since the output has a polarization dependence that varies depending on the polarization, the X polarization (X) input to the light intensity modulator 124 considering the polarization dependence of the light intensity modulator 124 is optimized to have an accurate polarization state in the X-axis direction. Needs to be. Accordingly, the first polarization controller 141 precisely adjusts the X polarization X to improve the accuracy of modulation, and transmits it to the light intensity modulator 142.

The light intensity modulator 142 receives the x element (E _x ) among the converted data (E) obtained by the data converter 130, and the first polarization controller 141 according to the value of the x element (E _x ) Adjust the light intensity of transmitted X polarization (X). The light intensity modulator 142 adjusts the light intensity of the X polarization X to a predetermined size when the value of the x element E _x is A, and when the value of the x element E _x is 0, the X polarization ( The intensity of X) is adjusted to be 0, and when the value of the element x (E _x ) is -A, it is output by adjusting the X polarization (X) to have a predetermined size in the -X axis direction.

The second polarization controller 143 modulates the second polarization unit 150 by adjusting the intensity of the X-polarized light X, which is intensity-modulated by the light intensity modulator 142, to be in the X-axis direction (or -X-axis direction) again. To be perpendicular to the output Y polarization (Y).

Similarly, the second modulator 150 also includes a light intensity modulator 152 disposed between the two polarization regulators 151 and 153 and the two polarization regulators 151 and 153. The two polarization controllers 151 and 153 are disposed before and after the light intensity modulator 152, Y polarization Y input to the light intensity modulator 152, and Y polarization Y output from the light intensity modulator 152. ) Is precisely adjusted in the Y-axis direction.

The first modulator 150 and the second modulator 150 include two polarization regulators (141, 143, (151, 153)) before and after the light intensity modulators 142, 152, respectively, X By accurately controlling the directions of polarization (X) and Y polarization (Y), interference between X polarization (X) and Y polarization (Y) can be minimized.

In addition, the light intensity modulator 152 receives the y element E _y among the transform data E, and of the Y polarization Y transmitted from the first polarization controller 151 according to the value of the y element E _y . Output by adjusting the light intensity.

The polarization combiner 160 combines the X polarization (X) and the Y polarization (Y) transmitted from the first modulator 140 and the second modulator 150 to output a transmission polarization signal to the optical line 300. .

The light receiving device 200 includes a linear polarization regulator 210, a polarization divider 220, a first photo detector 230, a second photo detector 240, and a data restoration unit 250.

The linear polarization controller 210 receives a received polarization signal from which the transmitted polarization signal is transmitted through the optical line 300, extracts linear polarization from the received received polarization signal, and outputs the polarized light. As described above, in the optical transmission apparatus 100, even though each of the X polarization (X) and the Y polarization (Y) is applied to the optical line 300 as linear polarization with respect to the X-axis and Y-axis directions, the optical line 300 is Through which the polarization state is changed while being transmitted to the light receiving device 200. In this case, each of the X polarization (X) and the Y polarization (Y) may not only change the polarization angle, but also may change the linear polarization into circular polarization or elliptical polarization. The linear polarization controller 210 removes circular polarization and elliptical polarization from the received polarization signal transmitted through the optical line 300 and filters so that only linear polarization is transmitted. Here, the linear polarization controller 210 may be used as a 45-degree linear polarization regulator to prevent errors caused by signal power imbalance during demodulation by uniformly adjusting the ratio of the signals carried on X and Y polarization.

The polarization divider 220 receives the linearly polarized light extracted from the linearly polarized light regulator 210, and distributes the applied linearly polarized light into X polarization X in a predetermined X-axis direction and Y polarization Y in a Y-axis direction. The polarization divider 220 receives the light and distributes it into X polarization (X) and Y polarization (Y), like the polarization divider 120 of the optical transmission device 100. Then, the distributed X polarization (X) is transmitted to the first photo detector 230, and the Y polarization (Y) is transmitted to the second photo detector 240.

The first photodetector 230 and the second photodetector 240 constitute a photodetector, and each receives a corresponding polarization among X polarization (X) and Y polarization (Y) distributed by the polarization distributor 220, respectively. The light intensity of polarization is detected and X polarization values (S _x ) and Y polarization values (S _y ) are transmitted to the data restoration unit 250.

The data restoration unit 250 receives the X polarization values S _x and Y polarization values S _y detected by the first and second photo detectors 230 and 240, and the X polarization values S _x and Y Received transformed data (RE = {RE ₀ , RE ₁ , RE ₂ ,) by restoring the transformed data (E = {E ₀ , E ₁ , E ₂ , ... E _N }) by synchronizing the polarization values (S _y ) ... RE _N }). Then, the input data (D = {D ₁ , D ₂ , D ₃ ,... D _N }) are restored according to the change of the received reception conversion data RE.

The X polarization values S _x obtained in the first and second photo detectors 230 and 240 correspond to the x element E _x of the transform data E, and the Y polarization value S _y is the y element ( E _y ).

And a data restoring unit 250 receives the converted data (RE _n) a, as obtained by one, and shown in Figure 4, the previously acquired reception conversion data (RE _n-1) with the received transform data acquisition current (RE to recover the data input (D _n) from a change between the _n).

The data restoration unit 250 sets the x element (RE _xn ) of the received transform data RE _n obtained as an example as a real part, and sets the y element (RE _yn ) as an imaginary part, thereby setting the received transform data (E _n ). E _xn + j (E _yn ) can be expressed in complex form, and input data (D) from the phase change between the previous received transform data (RE _n-1 ) and the current received transform data (RE _n ) expressed in complex form _n ) can be extracted. That is, based on Equation 1, if the phase change between the previous received transform data RE _n-1 and the current received transform data RE _n is π/2, the input data D _n is acquired as “1”, When the phase change is -π/2, input data D _n may be obtained as “0”.

The data restoration unit 250 may obtain the received transformed data RE by applying the X polarization values S _x and Y polarization values S _y as the x elements E _x and y elements E _y . However, the threshold range α is set so that the values of the x elements (RE _x ) and y elements (RE _y ) are not misidentified due to noise, and the x elements (E _x ) and y elements (E) according to the threshold range. _It is possible to determine whether _y ) is 0 or one of a positive value (A) and a negative value (-A) to obtain received transform data (RE).

For example, if the X polarization value S _x and the Y polarization value S _y are respectively within a predetermined threshold range α, the data restoration unit 250 includes the x element RE _x of the received conversion data RE. ) And the y element (RE _y ) can be determined to have a value of 0, and if the threshold range (α) is exceeded, the x element (RE _x ) and the y element (RE _y ) can be determined to be the value of A, and the threshold range ( α) is set to -0.1 ≤ α ≤ 0.1 when the range of the X and Y polarization values output from the first and second photo detectors 230 and 240 is -1 ≤ S _x and S _y ≤ 1, for example. Can be.

On the other hand, the data restoration unit 250 previously received received conversion data (RE _n-1 ) of the value of the element x (RE _xn-1 ) and the value of the y element (RE _yn-1 ) and the currently determined received conversion data ( according to the change value and the respective value of the y element (RE _yn) of the element x (RE _xn) of the RE _n) can obtain the input data (D _n). That is, compared to the value of the previous x element (RE _xn-1 ) and the value of the y element (RE _yn-1 ), the change in the value of the x element (RE _xn ) and the value of the y element (RE _yn ) is negative (- If it is A), the input data D _n can be acquired as "1", and if it is a positive change (A), it can be acquired as "0".

As described above, the polarization state of the transmitted polarization signal (R(t _n ) while the transmitted polarization signal in which the differential polarization transition is modulated in the optical transmission device 100 is transmitted to the optical reception device 200 through the optical line 300 ) Is changed, so the relationship between the current received transform data RE _n and the previous received transform data RE _n-1 and the transform data E _n and the previous transform data E _n-1 is Can be expressed together.

Here, since the change of the polarization state (R(t _n )) by the optical line 300 changes slowly in hundreds of μs, it is very slow compared to the symbol period of the transmission polarization signal. That is, the polarization state R(t _n-1 ), R( while the previous received transform data RE _n-1 and the current received transform data RE _n used to acquire the input data D _n are acquired. t _n )) is a negligible level (R(t _n-1 ) ≒ R(t _n )). Therefore, in Equation 2, it can be seen that the changes in polarization states (R(t _n-1 ) and R(t _n )) cancel each other, and the previous received transform data RE _n-1 and the received transform data RE _n . The ratio between appears equal to the ratio between the previous transform data E _n-1 and the transform data E _n .

In this embodiment, the optical transmission device 100 changes the value of the previous conversion data E _n-1 in response to the input data D _n to obtain the value of the conversion data E _n , and the optical reception device ( 200) restores the input data D _n from a change between the previous received conversion data RE _n-1 and the received conversion data RE _n , and thus the input data D _n applied to the optical transmission device 100 The relationship between and the input data D _n obtained from the light receiving device 200 may be expressed as Equation (3).

In Equation 3, R(t _n ) means a change in polarization state that occurs while the previous transform data E _n-1 and the transform data E _n are applied.

In Equation 3, the polarization state changes (R(t _n ), R(t _n-1 )) cancel each other. Therefore, the optical receiving device 200 is an optical transmitting device 100 without requiring a separate structure for tracking a complex structure for differential demodulation or a polarization state change (R(t _n ), R(t _n-1 )). It is possible to easily restore the input data D _n applied to.

That is, in accordance with the present embodiment, the reconstructed data RD _n is not obtained based on the single received transform data RE _n , but is continuously based on the change between the received transform data RE _n-1 and RE _n . As the recovery data RD _n is obtained by using, the recovery data RD _n corresponding to the input data D _n is accurately irrespective of changes in the polarization states R(t _n-1 ) and R(t _n ). Can be obtained.

In the above, the intensity and X intensity of the X polarization (X) of the received polarization signal is utilized by using the characteristic that the change of the polarization state (R(t _n )) by the optical line 300 is very slow compared to the symbol period of the transmission polarization signal. Polarization state (R(t _n-1 )) by acquiring reconstruction data (RD _n ) based on a change between received transform data (RE _n-1 , RE _n ) obtained by measuring the intensity of polarization (Y), Regardless of the change in R(t _n )), input data D _n can be accurately restored. That is, since input data D _n can be obtained without considering changes in polarization states R(t _n-1 ) and R(t _n ), a complex differential demodulation structure or a polarization state tracking means is not required. .

However, as the data restoring unit 250, in some cases, to obtain the input data (D _n) from the converted data (E _n-1, E _n) obtained, and the obtained conversion data (E _n-1, E _n), the It may be configured.

In this case, the optical transmission apparatus 100 includes x elements (E _x ) and y elements of a predetermined number (for example, two) of conversion data (E ₀ , E ₁ ) including the initial conversion data (E ₀ ). By specifying the value of (E _y ) in advance, the differential polarization transition can be modulated and transmitted. That is, after setting and transmitting a predetermined number of transform data as pilot data, transform data E ₂ , E ₃ , ..., E _n corresponding to the input data D _n may be transmitted.

The optical receiving device 200 receives the converted values of the received conversion data RE ₀ , RE ₁ , RE ₂ and the known conversion data E ₀ , E ₁ , and then converts the data E ₂ , E ₃ , .. ., E _n ) can be obtained according to Equation 3. In addition, input data D _n may be obtained from the obtained conversion data E ₂ , E ₃ , ..., E _n .

5 shows an optical transmission/reception method according to an embodiment of the present invention.

Referring to FIGS. 1 to 4, the optical transmission/reception method of this embodiment may be divided into a polarization transmission step (S10) and a polarization reception step (20 ). The polarization transmission step (S10) is performed in the optical transmission device 100, and the polarization reception step 20 is performed in the optical reception device 200.

)로 획득될 수 있으며, 초기 변환 데이터(E₀)는 기지정된 초기값(

)을 가질 수 있다. 그리고 변환 데이터(E)는 수학식 1에 따라 초기 변환 데이터(E₀)로부터 인가되는 입력 데이터(D)의 비트값에 따라 획득될 수 있다.In the polarization transmission step S10, first, the input data D to be transmitted is applied, and the applied input data D is converted into conversion data E according to a predetermined method (S11). The transform data (E) is a matrix form of 2 rows and 1 column to correspond to X polarization (X) and Y polarization (Y), respectively.

), and the initial conversion data (E ₀ ) is a predetermined initial value (

). And the conversion data E may be obtained according to the bit value of the input data D applied from the initial conversion data E ₀ according to Equation (1).

Meanwhile, the light emitted from the light source 110 is polarized and distributed in X polarization (X) and Y polarization (Y) in the vertical direction to each other (S12). And a distributed X polarization (X) and Y-polarized light (Y) x element (E _x = E _{x0 of converting each of the intensity data _{(E = {E 0, E} 1, E 2, ... E N}) , E _x1 , E _x2 , ... E _xN }) and y elements (E _y = {E _y0 , E _y1 , E _y2 , ... E _yN }) according to the control (S14). That is, the differential polarization transition is modulated by X polarization (X) and Y polarization (Y).

Then, the modulated X polarization (X) and Y polarization (Y) are combined to transmit a transmission polarization signal through the optical line 300 (S15).

On the other hand, in the polarization receiving step (S20), the first transmission polarization signal is applied to the received polarization signal transmitted through the optical line 300, and the circular polarization or elliptical polarization is filtered from the received reception polarization signal to extract linear polarization (S21). ). Then, the extracted linearly polarized light is distributed in a predetermined X-axis direction X polarization (X) and a Y-axis direction Y polarization (Y) (S22).

Thereafter, the intensity of each of the distributed X polarization (X) and Y polarization (Y) is detected to obtain an X polarization value (S _x ) and a Y polarization value (S _y ) (S24 ). Then, the received conversion data (RE = {RE) corresponding to the conversion data (E = {E ₀ , E ₁ , E ₂ , ... E _N }) from the X polarization values S _x and Y polarization values S _{y 0} , RE ₁ , RE ₂ , ... RE _N }) (S24 ). When the received transform data RE is obtained, the input data (D = {D ₁ , D ₂ , D ₃ ,... D _N }) is restored and obtained according to the change of the received received transform data RE (( S25).

In addition, as described above, in some cases, in the polarization transmission step (S10), the conversion data (for example, E ₀ , E ₁ ) having a predetermined number of known values is firstly transmitted by modulating the differential polarization transition with pilot data and , In the polarization reception step (S20 ), the conversion data E ₃ , E ₄ , and the received conversion data RE ₀ , RE ₁ , RE ₂ and the preset pilot data E ₀ , E ₁ according to Equation 3 ... E _N ), and input data (D = {D ₁ , D ₂ , D ₃ ,... D _N }) from the restored transform data (E ₃ , E ₄ , ... E _N ) It can also be obtained.

The method according to the present invention may be implemented as a computer program stored in a medium for execution on a computer. The computer readable medium herein can be any available medium that can be accessed by a computer, and can also include any computer storage medium. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, and ROM (readable) Dedicated memory), RAM (random access memory), CD (compact disk)-ROM, DVD (digital video disk)-ROM, magnetic tape, floppy disk, optical data storage, and the like.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom.

Therefore, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

100: optical transmitting device 200: optical receiving device
300: optical line 110: light source
120: polarization divider 130: data conversion unit
140: first modulator 150: second modulator
160: polarization coupler 210: linear polarization regulator
220: polarization distributor 230: first photodetector
240: second photodetector 250: data restoration unit

Claims (12)

A polarization distributor for polarizing distribution of light emitted from the light source to X polarization and Y polarization in a vertical direction to each other;
A data converter configured to obtain transformed data by varying x elements and y elements of previously obtained transformed data according to input data;
A modulator for adjusting the light intensity of each of the X polarization and the Y polarization according to the x and y elements of the converted data; And
A polarization combiner that combines X-polarized light and Y-polarized light to obtain a transmitted polarization signal; Included.
The data conversion unit
Based on the previously obtained transform data (E _n-1 ) and the input data (D _n ), the transform data (E _n ) is expressed by the equation

(Where M _θ is a state conversion function for converting the X polarization (X) and Y polarization (Y) of the previous transform data (E _n-1 ) according to the input data (D _n ).

, And θ is a polarization rotation angle corresponding to the input data D _n , and if the value D _n of the input data is “1”, π/2 rotation (SOP) from the polarization angle of the previous conversion data E _n-1 + π/2), and if it is "0", -π/2 turns (SOP-π/2).)
Optical transmission device obtained according to.
delete The method of claim 1, wherein the data conversion unit
An optical transmission device that is set in advance so that the x element and the y element of the initial transform data E ₀ have different predetermined initial values. A linear polarization regulator that extracts linear polarization by filtering circular polarization and elliptical polarization in the received polarization signal applied through the optical line;
A polarization divider for distributing the linearly polarized light extracted from the linearly polarized light regulator into a predetermined X-axis direction X polarization and a Y-axis direction Y polarization;
A light detection unit that detects light intensities of the X polarization and the Y polarization and obtains X polarization and Y polarization values; And
The received transform data having the x and y elements corresponding to the X polarization value and the Y polarization value is acquired, and the optical transmission apparatus transmits the received transform data by using changes in the x and y elements A data restoration unit to restore input data; Including,
The data restoration unit
An optical receiving apparatus for expressing the received transform data having x elements and y elements in a complex number form, and acquiring the input data according to a phase change between the previous received transform data expressed in a complex number form and the current receive transform data.
delete The method of claim 4, wherein the data restoration unit
Equation based on the initial predetermined number of received transform data (RE ₀ , RE ₁ , RE ₂ ) and pre-stored pilot transform data (E ₀ , E ₁ ) among the received transform data continuously acquired.

(Where R(t _n ) represents the change in polarization state that occurs while the previous conversion data (E _n-1 ) and the conversion data (E _n ) are applied, and R(t _n-1 ) ≒ R(t _n ) .)
According to the subsequent conversion data (E ₂ , E ₃ , ..., E _N ) to obtain, and to restore the input data from the change of the obtained conversion data (E ₂ , E ₃ , ..., E _N ) Optical receiving device. Distributing polarized light emitted from the light source into X polarization and Y polarization in a vertical direction to each other;
Obtaining transformed data by varying x and y elements of previously obtained transformed data according to input data;
Adjusting light intensity of each of the X polarization and the Y polarization according to the x element and the y element of the converted data; And
Obtaining a transmission polarization signal by combining X polarization and Y polarization whose light intensity is adjusted, and transmitting the obtained transmission polarization signal through an optical path; Including,
The step of acquiring the converted data is
Based on the previously obtained transform data (E _n-1 ) and the input data (D _n ), the transform data (E _n ) is expressed by the equation

(Where M _θ is a state conversion function for converting the X polarization (X) and Y polarization (Y) of the previous transform data (E _n-1 ) according to the input data (D _n ).

, And θ is a polarization rotation angle corresponding to the input data D _n , and if the value D _n of the input data is “1”, π/2 rotation (SOP) from the polarization angle of the previous conversion data E _n-1 + π/2), and if it is "0", -π/2 turns (SOP-π/2).)
Optical transmission method obtained according to.
delete The method of claim 7, wherein the step of obtaining the conversion data
An optical transmission method in which the x elements and y elements of the initial transform data E ₀ are set in advance to have different predetermined initial values. Filtering the circularly polarized light and elliptical polarized light from the received polarization signal applied through the optical line to extract linearly polarized light;
Distributing the extracted linearly polarized light into a predetermined X-axis direction X polarization and a Y-axis direction Y polarization;
Detecting the light intensity of each of the X polarization and the Y polarization to obtain an X polarization value and a Y polarization value; And
The received transform data having the x and y elements corresponding to the X polarization value and the Y polarization value is acquired, and the optical transmission apparatus transmits the received transform data by using changes in the x and y elements Restoring input data; Including,
The step of restoring the input data is
A method of optical reception, wherein the received transform data having x elements and y elements is expressed in a complex number form, and the input data is obtained according to a phase change between the previous received transform data expressed in a complex number form and the current received transform data.
delete The method of claim 10, wherein restoring the input data is
Equation based on the initial predetermined number of received transform data (RE ₀ , RE ₁ , RE ₂ ) and pre-stored pilot transform data (E ₀ , E ₁ ) among the received transform data continuously acquired.

(Where R(t _n ) represents the change in polarization state that occurs while the previous conversion data (E _n-1 ) and the conversion data (E _n ) are applied, and R(t _n-1 ) ≒ R(t _n ) .)
According to the subsequent conversion data (E ₂ , E ₃ , ..., E _N ) to obtain, and to restore the input data from the change of the obtained conversion data (E ₂ , E ₃ , ..., E _n ) Method of receiving light.

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