JP2003174416A - Optical signal monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To monitor whether or not an optical signal to be monitored is changed from the original in the state of an optical signal level. <P>SOLUTION: This optical signal monitoring device for monitoring an optical signal added with a parity bit so that the number of bits having 1 can be odd- numbered is constituted of a means constituted of optical arithmetic means in the number of stages corresponding to the bit length of an optical signal to be monitored where the optical arithmetic means in the mostfront stage inputs an optical signal to be monitored, and the other optical arithmetic means input the optical signals of the optical arithmetic means in the pre-stages, and each optical arithmetic means branches the input optical signal into two, and delays one of those input optical signal for one bit of the input optical signal, and executes an EOR arithmetic operation corresponding to the bits of the branched two input optical signals synchronously with an optical clock signal having a cycle which is 1/2 of that of the input optical signal and a means for monitoring the signal value of the optical signal to be outputted by the optical arithmetic means in the last stage. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical signal monitoring apparatus for monitoring whether or not an optical signal has changed from the original one, and more particularly to an optical signal monitoring apparatus capable of monitoring the optical signal level. Optical signal monitoring device.

Techniques for increasing the speed of optical communication are being advanced. In order to realize this speeding up, it is necessary to speed up the technique for monitoring whether or not the optical signal has changed from the original one.

[0003]

2. Description of the Related Art As a method for monitoring whether or not a transmitted optical signal has changed from the original one, a configuration is adopted in which a parity bit is added to an optical signal to be transmitted on the transmitting side. By converting the received optical signal into an electric signal on the receiving side and counting the number of 1 bits of the converted electric signal, whether or not the transmitted optical signal has changed from the original one The method of monitoring whether or not is widely used.

That is, on the transmitting side, a parity bit is added to the optical signal to be transmitted so that the number of bits having 1 becomes an odd number (or even number), and the receiving side receives it. By converting the optical signal to an electrical signal, counting the number of 1 bits of the converted electrical signal, and checking whether it is an odd number (or even number), the transmitted optical signal is originally The method of monitoring whether or not the thing has changed is widely used.

[0005]

However, in the prior art, the optical signal to be monitored is once converted into an electrical signal, and the number of 1 bits of the converted electrical signal is counted, and if it is an odd number or an even number. By checking whether or not there is any, the method of monitoring whether or not the optical signal to be monitored has changed from the original one is adopted.

That is, in the prior art, a method of once converting an optical signal to be monitored into an electrical signal to monitor whether or not the optical signal to be monitored has changed from the original one is disclosed. I am collecting.

According to the prior art, therefore, there is a problem in that, when the speed of the optical communication is further increased, the optical signal transmitted by such high-speed optical communication cannot be monitored.

The present invention has been made in view of the above circumstances, and has a new feature that enables monitoring of whether or not the optical signal to be monitored has changed from the original one in the state of the optical signal level. The purpose of the present invention is to provide a simple optical signal monitoring device.

[0009]

In order to achieve this object, the optical signal monitoring apparatus of the present invention monitors an optical signal to which a parity bit is added so that the number of bits having 1 is odd. In this case, the number of stages according to the bit length of the optical signal to be monitored (n stages when the bit length of the optical signal to be monitored is 2 ⁿ bits) is configured by the optical operation means. The optical signals to be monitored are input to the optical calculation means in the front stage, and the optical signals output from the optical calculation means in the front stage are input to the other optical calculation means. The input is branched into two, one of which is delayed by one bit of the input optical signal, and the input optical signal which is delayed and is not delayed in synchronization with the optical clock signal having a cycle of "1/2" of the input optical signal. EO that supports bits with optical signals A first unit configured to execute a calculation and output an optical signal as a result of the calculation and a second unit to monitor a signal value of the optical signal output from the last-stage optical calculation unit are provided. To configure.

In the optical signal monitoring apparatus of the present invention configured as described above, for example, the optical signal portion has an optical signal (1
(A parity bit of a bit is added) as a monitoring target, the first means receives the optical signal of the monitoring target as an input, branches the optical signal of the monitoring target into two, and outputs one of the optical signals of the monitoring target. A bit-corresponding EOR between the delayed input optical signal and the non-delayed input optical signal in addition to delaying the signal by 1 bit and synchronizing with the optical clock signal having a "1/2" cycle of the monitored optical signal. A first optical operation unit that executes an operation and outputs an optical signal (2 bits) as a result of the operation and an optical signal output from the first optical operation unit are input, and the input optical signal is branched into two. Then, one of them is delayed by 1 bit of the input optical signal (2 bits of the monitored optical signal), and an optical clock signal having a cycle of "1/2" of the input optical signal (the monitored optical signal Optical clock signal with "1/4" period ) To synchronously, the bit corresponding EOR of the input optical signal not delayed and the input optical signal delayed
Second optical operation means for executing an operation and outputting an optical signal (1 bit) as a result of the operation.

According to this configuration, the first optical calculation means is
For example, when an optical signal to be monitored called "1011 (the least significant bit is a parity bit)" is input, an optical clock signal having a cycle of "1/2" of the optical signal to be monitored as shown in the upper part of FIG. In synchronism with the above, the EOR operation corresponding to the bits of “1011” and “1011” delayed by 1 bit is executed to obtain an optical signal of “10” and output it.

In response to the optical signal output from the first optical operation means, the second optical operation means, as shown in the lower part of FIG. 1, outputs an optical signal having a cycle of "1/2" of the input optical signal. In synchronization with the clock signal, the EOR operation corresponding to the bit of "10" and "10" delayed by 1 bit is executed to obtain an optical signal of "1" and output it.

Further, according to this configuration, when the optical signal to be monitored, for example, "1110 (the least significant bit is the parity bit)" is input to the first optical operation means, as shown in the upper part of FIG. By performing an EOR operation corresponding to bits of “1110” and “1110” delayed by one bit in synchronization with an optical clock signal having a cycle of “½” of the target optical signal, It obtains an optical signal "01" and outputs it.

In response to the optical signal output from the first optical operation means, the second optical operation means, as shown in the lower part of FIG. 2, outputs an optical signal having a cycle of "1/2" of the input optical signal. In synchronization with the clock signal, an EOR operation corresponding to a bit of "01" and "01" delayed by 1 bit is executed to obtain an optical signal of "1" and output it.

As described above, the first means outputs the optical signal "1" when the optical signal to be monitored is a regular one, so that the second means has the first means " By monitoring whether or not the optical signal "1" is output, it is monitored whether or not the optical signal to be monitored has changed from the original one.

As described above, according to the present invention, it is possible to monitor whether or not the optical signal to be monitored has changed from the original one in the state of the optical signal level. The optical communication system can be constructed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail according to embodiments.

FIG. 3 shows an example of an optical communication system including the optical signal monitoring apparatus 1 of the present invention.

As shown in this figure, the optical signal monitoring apparatus 1 of the present invention is, for example, an optical signal having an odd parity bit transmitted through an optical communication line (so that the number of bits having 1 becomes an odd number). And optical signal with parity bit added)
The optical signal output from the all-optical configuration repeater 2 that relays the optical signal is monitored, and processing is performed to monitor whether the optical signal has changed from the original one.

FIG. 4 shows an embodiment of the optical signal monitoring apparatus 1 of the present invention. Here, in this embodiment example, 1
It is assumed that an 8-bit optical signal to which an odd parity bit is added is to be monitored.

The optical signal monitoring apparatus 1 of the present invention shown in this figure
Is a first optical operation mechanism 10-1 having an all-optical configuration.
And a second optical operation mechanism 10-2 having an all-optical configuration
And the third optical operation mechanism 10-3 having an all-optical configuration
And a monitoring mechanism 20 including a light receiving element and an electronic circuit.

The first optical operation mechanism 10-1 receives an optical signal to be monitored (optical signal output by the all-optical configuration repeater 2) as an input, branches the input optical signal into two, and outputs one of them. An optical branching delay mechanism 11-1 having an all-optical configuration that delays the input optical signal by 1 bit using the delaying optical fiber 30 and does not delay the other optical signal, and "1/2" of the optical signal to be monitored. An optical clock signal having a period of "(shown in the figure) is used as a signal light input, and an optical signal delayed by the optical branch delay mechanism 11-1 and an optical signal not delayed are used as control light inputs. It is composed of an SMZ-SOA (symmetrical Mach-Zehnder type semiconductor optical amplifier) 12-1 having an optical configuration and performs a process of outputting a 4-bit optical signal.

The second optical operation mechanism 10-2 receives the optical signal output from the first optical operation mechanism 10-1 as an input and branches the input optical signal into two, one of which is the delay optical fiber 30. To delay the input optical signal by 1 bit (2 bits of the monitored optical signal) and not delay the other optical branching delay mechanism 11-2 and the input optical signal An optical branch delay mechanism using an optical clock signal having a cycle of "1/2" (shown in the figure, an optical clock signal having a cycle of "1/4" of an optical signal to be monitored) as a signal light input. 11-2 SMZ-S having an all-optical configuration in which an optical signal delayed by the optical signal and an optical signal not delayed by the optical signal are controlled optical inputs
It is composed of the OA 12-2 and performs a process of outputting a 2-bit optical signal.

The third optical operation mechanism 10-3 receives the optical signal output from the second optical operation mechanism 10-2 as an input and branches the input optical signal into two, one of which is the delay optical fiber 30. To delay the input optical signal by 1 bit (4 bits of the monitored optical signal) and not delay the other optical branching delay mechanism 11-3 of the optical configuration and the input optical signal An optical branching delay mechanism using an optical clock signal having a cycle of "1/2" (shown in the figure as an optical clock signal having a cycle of "1/8" of the monitored optical signal) as a signal light input. 11-3 SMZ-S having an all-optical configuration in which an optical signal delayed by the optical signal and an optical signal not delayed by the optical signal are controlled optical inputs
It is composed of the OA 12-3 and performs processing for outputting a 1-bit optical signal.

The monitoring mechanism 20 is the third optical operation mechanism 10-3.
Converts the 1-bit optical signal output from the optical signal into an electrical signal, and converts the optical clock signal (optical clock signal indicated by in the figure) used by the third optical operation mechanism 10-3 into an electrical signal. While synchronizing with the electrical conversion signal of the optical clock signal, it is checked whether or not the level value of the electrical conversion signal of the optical signal output by the third optical operation mechanism 10-3 is "1", and the level is checked. When the value indicates "1", it outputs that the monitored optical signal is original, and when the level value indicates "0", it outputs that the monitored optical signal is not original. To do.

Here, the optical clock signal is realized by, for example, preparing a plurality of injection-locked lasers (lasers capable of setting the oscillation frequency of laser light) and using the optical signals generated by those injection-locked lasers. Or, prepare one laser that oscillates a laser beam having a "1/2" period of the optical signal to be monitored, and prepare an optical frequency dividing circuit that is configured by connecting optical switches in multiple stages. , By using an optical signal divided by these optical switches.

Each SMZ-SOA 12-1, 2, 3 has two S
By adopting a configuration including an OA (semiconductor optical amplifier) 50, an optical clock signal is input as signal light to one of the SOAs 50, and the delayed optical signal amplified by the fiber amplifier 40 is used as a control light. , The optical clock signal is input to the other SOA 50 as signal light, and the undelayed optical signal amplified by the fiber amplifier 40 is input as control light to interfere with Mach-Zehnder interference. According to the measurement configuration, a signal light is caused to interfere, and the interference light is extracted using an optical filter 60 (having a filter characteristic of blocking the control light and transmitting the signal light).

SO constituting SMZ-SOA 12-1, 2, 3
As shown in FIG. 5, A50 has an amplification characteristic that when the power of the control light is large, the output power of the signal light becomes smaller than when the power of the control light is small.

According to the amplification characteristic of the SOA 50, FIG.
As shown in, the output point of the fiber amplifier 40 that amplifies the optical signal that has not been delayed is represented by A, the input point of the SOA 50 that receives the optical signal is represented by α, and the output point is represented by γ. If the output point of the fiber amplifier 40 that amplifies the optical signal is B, the input point of the SOA 50 that inputs the optical signal is β, and the output point is δ, each SMZ-SOA12-
1, 2, 3 have output characteristics as shown in FIG.

That is, the optical signal (control light) at the point A is 1
When the optical signal at point B (control light) is 1, the optical power at point α (control light) is large and the optical power at point β (control light) is large, so the optical signal at point γ (control light) The signal light) is 0, and the optical signal at the δ point (signal light) is 0, so that interference does not occur and the SMZ-SOA 12-1, 2 and 3 output 0.

On the other hand, the optical signal (control light) at point A is 1, and B
When the optical signal at the point (control light) is 0, the optical power at the α point (control light) is large and the optical power at the β point (control light) is small, so the optical signal at the γ point (signal light) is Is 0 and the optical signal (signal light) at the δ point is 1, so that interference does not occur,
The SMZ-SOA 12-1, 2 and 3 output 1.

On the other hand, when the optical signal (control light) at point A is 0,
When the optical signal (control light) at the point is 1, the optical power (control light) at the α point is small and the optical power (control light) at the β point is large, so the optical signal (signal light) at the γ point Is 1, and the optical signal (signal light) at the δ point is 0, which causes no interference and
The SMZ-SOA 12-1, 2 and 3 output 1.

On the other hand, when the optical signal (control light) at point A is 0,
When the optical signal (control light) at the point is 0, the optical power (control light) at the α point is small, and the optical power (control light) at the β point is small, so the optical signal (signal light) at the γ point. Is 1, and the optical signal (signal light) at the δ point becomes 1, which causes interference, and S
The MZ-SOA 12-1, 2, 3 outputs 0.

As can be seen from this, each SMZ-S
The OAs 12, 1, 2, and 3 operate so as to perform an EOR operation corresponding to the bit of the undelayed optical signal and the delayed optical signal and output the optical signal of the operation result. become.

Next, the optical signal monitoring processing executed by the optical signal monitoring apparatus 1 of the present invention having such a configuration will be described.

(1) For example, as an optical signal to be monitored,
It is assumed that an optical signal "10011000 (the least significant bit is a parity bit)" is input.

The optical signal to be monitored "1001100"
In response to the input of "0", the first optical operation mechanism 10-1 operates as shown in FIG.
As shown in the upper part of FIG. 4, “10011000” and 1 are set in synchronization with an optical clock signal (optical clock signal shown in FIG. 4) having a cycle of “1/2” of the monitored optical signal.
By performing an EOR operation corresponding to a bit with "10011000" delayed by a bit, an optical signal "1110" is obtained and output.

The second optical operation mechanism 10-2 receives the optical signal "1110" output from the first optical operation mechanism 10-1.
Is "1/2" of the input optical signal, as shown in the middle part of FIG.
By synchronizing with the optical clock signal having the period of (the optical clock signal shown in FIG. 4), the bit-corresponding EOR operation of "1110" and "1110" delayed by 1 bit is executed, It obtains an optical signal "01" and outputs it.

Upon receipt of the optical signal "01" output from the second optical operation mechanism 10-2, the third optical operation mechanism 10-3, as shown in the lower part of FIG. An EOR operation corresponding to a bit of "01" and "01" delayed by one bit is executed in synchronization with an optical clock signal having a cycle of 1/2 "(optical clock signal shown in Fig. 4). By doing so, an optical signal "1" is obtained and output.

Upon receiving the optical signal "1" output from the third optical operation mechanism 10-3, the monitoring mechanism 20 detects that the optical signal to be monitored is the original one according to the above-mentioned processing. , To that effect is output.

On the other hand, this monitored optical signal "10011"
000 ”is on the communication line, for example,“ 1 1 01100
Suppose that it has been transformed into something like "0".

At this time, the first optical operation mechanism 10-1
Outputs an optical signal “0110” as shown in the upper part of FIG. 9, and in response to this, the second optical operation mechanism 10-2
As shown in the middle part of FIG. 9, an optical signal of “11” is output, and in response to this, the third optical operation mechanism 10-3 outputs an optical signal of “0” as shown in the lower part of FIG. Because
The monitoring mechanism 20 detects that the optical signal to be monitored is not the original one according to the above-described processing, and outputs that effect.

(2) For example, assume that an optical signal "11010011 (the least significant bit is a parity bit)" is input as the optical signal to be monitored.

The optical signal to be monitored "1101001"
1 ", the first optical operation mechanism 10-1 receives the input of FIG.
As shown in the upper part of 0, "1/2" of the optical signal to be monitored
By performing an EOR operation corresponding to a bit of “11010011” and “11010011” delayed by one bit in synchronization with an optical clock signal having a period of (optical clock signal shown in FIG. 4), The optical signal "0100" is obtained and output.

The second optical operation mechanism 10-2 receives the optical signal "0100" output from the first optical operation mechanism 10-1.
As shown in the middle part of FIG.
An EOR corresponding to a bit of "0100" and "0100" delayed by one bit in synchronization with an optical clock signal having a cycle of 2 "(optical clock signal shown in FIG. 4).
By performing the calculation, we get an optical signal of "10",
Output it.

In response to the optical signal "10" output from the second optical operation mechanism 10-2, the third optical operation mechanism 10-3, as shown in the lower part of FIG. An EOR operation corresponding to a bit of "10" and "10" delayed by 1 bit is executed in synchronization with an optical clock signal having a cycle of 1/2 "(optical clock signal shown in FIG. 4). By doing so, an optical signal "1" is obtained and output.

In response to the optical signal "1" output from the third optical operation mechanism 10-3, the monitoring mechanism 20 detects that the optical signal to be monitored is the original one according to the above-mentioned processing. , To that effect is output.

On the other hand, the optical signal "11010" to be monitored is
011 ”is on the communication line, for example,“ 11 1 1001
Suppose that it has become a 1 ”.

At this time, the first optical operation mechanism 10-1
11 outputs an optical signal "0000" as shown in the upper part of FIG. 11, and in response to this, the second optical operation mechanism 10-2
11 outputs an optical signal "00" as shown in the middle part of FIG. 11, and in response to this, the third optical operation mechanism 10-3 causes the optical signal "0" as shown in the lower part of FIG. Therefore, the monitoring mechanism 20 detects that the optical signal to be monitored is not the original one according to the above-described processing, and outputs that effect.

In this way, the optical signal monitoring device 1 of the present invention can monitor whether or not the optical signal to be monitored has changed from the original one in the state of the optical signal level.

In the embodiment described above, the optical signal in which the parity bit is added to the least significant bit is targeted for monitoring. However, the present invention is applied to the optical signal in which the parity bit is added to the most significant bit. Can be applied as is.

In the embodiment, the optical signal to which the parity bit composed of 1 bit is added is to be monitored. However, the present invention is applicable to the optical signal to which the parity bit composed of a plurality of bits is added. Also, it can be applied as it is.

[0053]

As described above, according to the present invention,
It becomes possible to monitor whether or not the optical signal to be monitored has changed from the original one in the state of the optical signal level, which makes it possible to realize the construction of a high-speed optical communication system.

[Brief description of drawings]

FIG. 1 is an operation explanatory diagram of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention.

FIG. 3 is an example of an optical communication system including the present invention.

FIG. 4 is an example of an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an amplification characteristic of SOA.

FIG. 6 is an operation explanatory diagram of SMZ-SOA.

FIG. 7 is an operation explanatory diagram of SMZ-SOA.

FIG. 8 is a diagram illustrating the operation of the embodiment.

FIG. 9 is a diagram illustrating the operation of the embodiment.

FIG. 10 is a diagram illustrating the operation of the embodiment.

FIG. 11 is a diagram illustrating the operation of the embodiment.

[Explanation of symbols]

1 Optical signal monitoring device 10-1 First optical operation mechanism 11-1 Optical branch delay mechanism 12-1 SMZ-SOA 10-2 Second optical operation mechanism 11-2 Optical branch delay mechanism 12-2 SMZ-SOA 10-3 Third optical operation mechanism 11-3 Optical branch delay mechanism 12-3 SMZ-SOA 20 Monitoring mechanism 30 Optical fiber for delay 40 fiber amplifier 50 SOA 60 Optical filter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Ozeki             4-2-1 Kanaikitamachi, Koganei City, Tokyo Independent             Communications Research Institute F term (reference) 2K002 AA02 AB23 AB40 BA02 CA13                       DA08                 5K002 CA12 CA13 DA05 EA05 FA01

Claims (2)

[Claims] 1. An optical signal monitoring device for monitoring an optical signal to which a parity bit is added so that the number of bits having 1 becomes an odd number, and the number of stages is configured according to the bit length of the optical signal to be monitored. The optical operation means of the first stage is used as an input for the optical signal to be monitored, and the other optical operation means is used as an input for the optical signal output by the optical operation means of the previous stage. The calculating means branches the input optical signal into two and delays one of them by one bit of the input optical signal, and
The EOR operation corresponding to the bit of the delayed input optical signal and the non-delayed input optical signal is executed in synchronism with the optical clock signal having the “1/2” cycle of the input optical signal, and the optical result is calculated. An optical signal monitoring apparatus comprising: a unit configured to output a signal; and a unit configured to monitor a signal value of an optical signal output from the last-stage optical calculation unit. 2. The optical signal monitoring device according to claim 1, wherein the optical operation means receives the optical clock signal as a signal optical input, and the delayed optical signal and the non-delayed optical signal are control optical inputs. Optical signal monitoring device characterized by comprising a symmetrical Mach-Zehnder type semiconductor optical amplifier