JPH0497630A - Optical access node - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution by using an optical amplifier as an optical switch so as not to require a substantial optical switch. CONSTITUTION:An input photocoupler 50 branching an optical signal Si and outputting 1st and 2nd branch optical signals S1, S2 is provided and an output of the input photocoupler 50 is connected to an optical amplifier 52 being a light interrupt means via an optical delay line 51 giving a timing to an optical signal and an electric signal. The optical interrupt means interrupts the 2nd branch optical signal S2 in a timing when a timing circuit 54 outputs a transmission data and an output photocoupler 57 sends an output of a light source 56 to an idle area of an optical signal Si when the 2nd branch optical signal S2 is interrupted. Thus, a transmission data is written in an idle area of the optical signal, and the light interrupt means and the output photocoupler 57 act like an optical switch. Thus, no optical switch is required and the circuit constitution is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is directed to a wideband integrated 11 system in which various media information such as audio, computer data, and image data are processed on a single network.
The present invention relates to an optical access node that is used in a ring-shaped user home network in 1 (B-ISDN) and performs input/output of data within the network.

(Prior Art) Conventionally, as a technology in this type of field, there was one described in the material of the 6th Optical Switching Study Group of the Institute of Electronics, Information and Communication Engineers, "Configuration of a Broadband Subscriber Network Using Optical Switches."

FIG. 2 is a diagram of the main parts of the broadband integrated network described in the above-mentioned document.

This broadband integrated network includes a user home network 1o and a subscriber backbone 20.

The user home network 10 has terminal devices "○-1" such as telephones and computers, and optical access nodes 11 and 12.1314 are connected to each terminal device 10-1, respectively. Furthermore, each optical access node 11.12.13
．． 14 is connected in a ring shape by an optical fiber, and receives data addressed to itself from among the optical signals on the optical fiber and outputs it to the connected terminal device, and transmits data transmitted from the terminal device to the optical fiber. It has a function to send to.

The subscriber backbone 20 has a function of multiplexing and transmitting a large number of subscriber lines. This subscriber backbone 20
A local exchange 30 is connected to the .

FIG. 3 shows the conventional optical access node 1 in FIG.
1 is a configuration block diagram showing an example of the configuration of FIG.

This optical access node 11 includes an optical amplifier 11a that amplifies the input optical signal Si, an input optical coupler llb that branches the input optical signal Si, an optical delay line 11c, an optical switch lid, and converts the input optical signal Si into an electrical signal. It has a receiving circuit lie, which are connected via an optical fiber. Further, between the output side of the receiving circuit 11e and the optical switch lid, a timing circuit 111f for detecting the received data Dr,
Semiconductor laser 11 that converts transmission data Di into an optical signal
g. An optical switch drive circuit 11h for driving the optical switch is connected. And timing 111
A terminal device 11-1 is connected to f.

Next, the operation will be explained.

The input optical signal Si is amplified by the optical amplifier 11a, and branched into the first and second branched optical signals 5IS2 by the optical coupler llb. Among them, the first branched optical signal S1 is transmitted to the receiving circuit 11e.
The signal is converted into an electrical signal by the timing circuit 11f, and processed as follows.

(1) If the received data is not addressed to itself and does not need to be sent to the terminal device 11-1, the optical switch drive circuit 11h is controlled and the second branch optical signal S2 is sent to the output side of the optical switch lid. Optical switch ll to output from
Switch d.

(2) If the received data is addressed to itself, the received data Dr is sent to the terminal device 11-1.

(3> When transmitting the transmission data Di from the terminal device 11-1, at the same time as the optical signal is transmitted from the light source 11g,
The optical switch lid is switched so that the second branched optical signal S2 is blocked.

(Problems to be Solved by the Invention) However, in the optical access node with the above configuration, an optical amplifier is required to amplify the optical signal in order to prevent the optical signal from being attenuated due to insertion loss of the optical switch lid.
There was a problem that the circuit configuration became complicated.

Furthermore, when using a dielectric optical switch such as LiNb3,
Its characteristic is that the operating voltage is higher than that of an electric circuit, so a separate power supply system for the optical switch is required. Furthermore, there is a problem in that the operating stability is not good, such as the operating voltage changing due to temperature changes, and the performance of the entire optical access node is limited.

The present invention provides an optical access node that solves the problems of the prior art in that the circuit configuration becomes complicated and the performance is limited due to the use of optical switches.

(Means for Solving the Problems) In order to solve the above problems, the present invention branches an optical signal having an empty area and outputs first and second branched optical signals. an input optical coupler; a receiving circuit that converts the first branched optical signal branched by the input optical coupler into an electrical signal and outputs received electrical data; In an optical access node, the optical access node includes a timing circuit that detects the sky area and outputs external transmission data at the timing of detecting the empty area in the received electrical data, and a light source that converts the transmission data into an optical signal. The following measures were taken. a light blocking means for blocking the second branched optical signal at a timing when the timing circuit outputs the transmission data; and a light blocking means for transmitting the output of the light source to the empty area of the optical signal when the second branched optical signal is blocked. An output optical coupler is provided.

(Function) Since the present invention configures the optical access node as described above, the optical cutoff means cuts off the second branch optical signal at the timing when the timing circuit outputs the transmission data. The output optical coupler sends the output of the light source to the empty area of the optical signal when the second branched optical signal is cut off.Thereby, the transmission data is written in the empty area of the optical signal, and the optical coupler and the output optical coupler send the output of the light source to the empty area of the optical signal. It can act as an optical switch.

Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is a configuration block diagram of an optical access node showing an embodiment of the present invention.

This optical access node is used for the optical access node in the broadband network shown in FIG. 2, and is used in place of the optical access node shown in FIG.

This optical access node splits the optical signal Si into a first
and second branched optical signal S1. , S2, and the output side of the input optical coupler 50 is an optical delay line 5 that measures the timing of the optical signal and the electrical signal.
1 to an optical amplifier 52 which is a light blocking means. The optical amplifier 52 is composed of a semiconductor laser, an antireflection film, an optical lens, and the like.

On the other hand, on the output side of the input optical coupler 50, a receiving circuit 53 is provided.
is connected. The receiving circuit F453 is an input optical coupler 5.
It has a function of converting the first branched optical signal S1 branched by 0 into an electrical signal and outputting received electrical data.

Further, a timing circuit 54 is provided on the output side of the receiving circuit 53.
or connected.

The timing circuit r@54 is composed of an LSI or the like, and detects predetermined received data Dr in the received electrical data and outputs it to the terminal device 111, and also outputs it to the terminal device 111 at the timing of detecting an empty area in the received electrical data. It has a function of outputting the transmission data Di from ff1l-1-. and,
The output side of the timing circuit 54 is connected to an optical amplifier drive circuit 55 for driving the optical amplifier 52 and a light source 56, respectively. The light source 56 is composed of a semiconductor laser or the like, and has a function of converting the transmission data Di into an optical signal.

The optical amplifier 52 also has a function of blocking the second branched optical signal S2 using the drive signal output from the optical amplifier drive circuit 55 at the timing when the timing circuit i54 outputs the transmission data Di to the light source 56. are doing. Then, the output of the optical amplifier 52 and the light source 56 (in principle, the output optical coupler 5
6 is connected.

In the optical access node configured as above, (A
>Operations during reception and (B) operations during transmission will be explained.

(A> When an optical signal Si is input to the optical coupler 50 for operation input during reception, the optical signal Si is branched into first and second branched optical signals S1 and S2. The first branched optical signal S1 is converted into an electrical signal in reception cycle 1@53 and output to the timing circuit 54 as received electrical data.

Timing circuit 54 decodes attos in the received electrical data. If the received electrical data is not self-receiving data Dr, a control signal is output to the optical amplifier drive circuit 55 to cause the optical amplifier 52 to output a drive current. In response to this drive current, the optical amplifier 52
The branched optical signal S2 is amplified and outputted to the input side of the next stage optical access node (not shown) via the output optical coupler 57. In addition, the received electrical data is self-luminous received data D
If r, the received data Dr is sent to the terminal device 11-1-
Send to.

(B) Operation during transmission: A transmission request is output from the terminal device 11-1 to the timing circuit 54. The timing circuit 54 that has received the transmission request monitors the received electrical data from the receiving circuit 53 and detects an empty area in the received electrical data. When the empty area is detected, permission is given to the terminal device 11-1 to transmit data. After receiving that permission, the terminal device 11
-1 sends the transmission data Dj to the timing circuit 54.

The timing circuit 54 then controls the drive circuit 55 so that the drive current to the optical amplifier 52 does not flow. As a result, the optical amplifier 52 blocks the second branched optical signal S2. On the other hand, transmission data D output from the terminal device 11-1
i is converted into an optical signal by a light source 56. Furthermore, since the timing is determined by the optical delay line 51, the transmission data Di converted into an optical signal is sent from the output optical coupler 57 to the empty area of the optical signal Si.

The optical amplifier 52 has a property of hardly allowing the second branch optical signal S2 to pass unless a drive current from the drive circuit 55 is applied. In this embodiment, the optical amplifier 52 is used as an optical switch by taking advantage of this property, so the optical switch is not required and the circuit configuration can be simplified. Further, there are advantages such as the voltage used is only the voltage of the electric circuit, no separate power supply system is required, and the optical element to be driven is only the optical amplifier 52, which reduces power consumption by the amount of the optical switch driving circuit. be.

Note that the present invention is not limited to the illustrated embodiment, and various modifications are possible. For example, there are the following variations.

(I> In the above embodiment, the optical delay line 51 is provided between the input optical coupler 0 and the optical amplifier 52, but the optical delay line 51 is not limited to this, and is provided between the output optical coupler 57 and the optical amplifier 52. You can.

(n) Although a semiconductor laser is used as the light source 56 and an optical amplifier 52 is used as the light blocking means, the present invention is not limited thereto as long as it meets the spirit of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the timing circuit cuts off the second branch optical signal at the timing when outputting the transmission data, and when the second branch optical signal is cut off, the transmission data Since the output of the light source is sent to the empty area of the optical signal, both the light blocking means and the output optical coupler function as an optical switch, and the conventionally necessary optical switch becomes unnecessary. Therefore, the circuit configuration can be simplified.
It is expected that the voltage used will be only the voltage of the electric circuit, eliminating the need for a separate power supply system, and that operational stability will be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an optical access node showing an embodiment of the present invention, FIG. 2 is a diagram of main parts of a broadband integrated network, and FIG. 3 is a block diagram of the configuration of a conventional optical access node. 50... Input optical coupler, 52... Optical amplifier, 53... Receiving circuit, 54...
Timing circuit, 56...Light source, 57...
...Output optical coupler, Si...Optical signal, Sl,
82...First and second branched optical signals.

Claims (1)

[Scope of Claims] An input optical coupler that branches an optical signal having an empty area and outputs first and second branched optical signals, and the first branched optical signal branched by the input optical coupler. a receiving circuit that converts the received electrical data into an electrical signal and outputs the received electrical data; In an optical access node including a timing circuit that outputs data and a light source that converts the transmission data into an optical signal, the timing circuit blocks the second branch optical signal at a timing when the transmission data is output. An optical access node comprising: a light blocking means; and an output optical coupler that sends the output of the light source to the empty area of the optical signal when the second branched optical signal is blocked.