JPH05183508A - Optical transmitter - Google Patents

Abstract

PURPOSE:To secure the synchronization of each reception information string by controlling a wavelength of an optical signal between active and standby optical transmission lines with the uninterruptible transmission line changeover system. CONSTITUTION:A transmission information string 100 being a changeover object is sent in parallel between an active optical transmission line 7 and a standby optical transmission line 8, and after the synchronization of reception information strings 200, 300 is secured, the lines are selected by an uninterruptible transmission line changeover means and a receiver side detects a phase difference between the reception information strings 200, 300 by an information string phase difference detection means 13. An optical wavelength change control means 5 generates each optical wavelength change signal for active and standby systems adaptive to the phase difference signal so that the sender side make the phase difference zero and an electrooptic conversion/optical wavelength change means 4 for the active and the standby system converts the electric signal of the transmission information string 100 into an optical signal according to each optical wavelength change signal and changes the wavelength of each transmission light and sends the result to the active and standby optical wavelength transmission lines 7, 8. Thus, the transmission capacity is not affected in comparison with a conventional logic synchronization system by the memory control requiring the storage capacity proportional to the transmission capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-instantaneous transmission line switching type optical transmission device for controlling the wavelength of an optical signal between a working optical transmission line and a standby optical transmission line to ensure synchronization of received information sequences.

[0002]

2. Description of the Related Art For example, a conventional optical transmission device (only a current optical transmission line to be switched among a plurality of active optical transmission lines is shown in Japanese Patent Laid-Open No. 1-264426) is shown in FIG.
The multiplexing conversion apparatus 1 allocates information strings from a plurality of terminals to predetermined bit positions in a frame and multiplexes them. The long frame pattern inserting circuit 2 sets a long frame pattern at the empty bit position in the output frame from the multiplexer / converter 1 that is more than twice the maximum transmission delay difference between the working and protection optical transmission lines 7 and 8. insert.

FIG. 6 is a block diagram showing the long frame pattern insertion circuit 2. Reference numeral 2a is a timing generation circuit for notifying the position of a time slot into which a long frame pattern is inserted with respect to an output frame from the multiplexer / converter 1 and 2b is a maximum transmission path delay difference between the working and protection optical transmission paths 7 and 8. A long frame pattern generation circuit 2c for generating a long frame pattern which is more than twice the selector 2c is a selector for inserting a long frame pattern into an empty bit position of an output frame from the multiplexing converter 1 based on a signal from the timing generation circuit 2a. Is.

The transmission side transmission line change-over switch 3 branches the same transmission information sequence 100 to each of the working and protection optical transmission lines 7 and 8 in response to a branching command from the transmission side data link circuit 6 and transmits them in parallel. Further, the working optical transmission line 7 is disconnected by a disconnection command from the receiving side data link circuit 14 via the transmitting side data link circuit 6 by the data link. Electric-optical conversion means 4a
Converts the electric signal of the parallel transmission information sequence 100 into an optical signal and sends it to the working and protection optical transmission lines 7 and 8. The optical-electrical converting means 9 converts the optical signals from the working and standby optical transmission lines 7 and 8 into electrical signals of the received information sequences 200 and 300, respectively, and also bit synchronous clocks 400 and 500.
To play. The long frame synchronizing circuit 12 reproduces long frame pulses 600 and 700 from the received information sequences 200 and 300 from the optical-electrical converting means 9 and the bit synchronizing clocks 400 and 500, respectively. The elastic store memory 16 has a storage capacity for the length of a long frame. Based on the phases of the long frame pulses 600 and 700 from the long frame synchronization circuit 12, the bit synchronization clocks 400 and 500 from the optical-electrical converting means 9 are used to receive information sequences 200 and 300 from the optical-electrical converting means 9, respectively. Write
On the other hand, in order to ensure the synchronization of the received information sequences 200 and 300 between the working and standby optical transmission lines 7 and 8, the long frame pulse 6 delayed by the delay circuit 17 by half the length thereof is used.
With the phase of 00 as the reference, with the bit synchronization clock 400,
The received information strings 200 and 300 are read. The receiving side transmission line changeover switch 10 disconnects the working optical transmission line 7 in response to a disconnection command from the receiving side data link circuit 14. Demultiplexer 11
Demultiplexes the multiplexed information string from the receiving-side transmission path changeover switch 10 and sends it to a plurality of terminals.

The above-mentioned conventional optical transmission apparatus synchronizes each received information sequence by controlling an elastic store memory having a storage capacity for the length of a long frame between the working and standby optical transmission paths. A method of switching after being secured (logically synchronous non-interruption transmission path switching method) is adopted.

[0006]

In the conventional optical transmission apparatus as described above, a logically synchronized non-interruption transmission line switching system by memory control which requires a storage capacity for the length of a long frame is adopted. There is a problem that the storage capacity increases in proportion to the transmission capacity.

The problem to be solved by the present invention does not affect the transmission capacity that is switched after the optical wavelength is controlled by the optical transmission device and the synchronization of each received information string is secured between the working and protection optical transmission lines. Method (Physically synchronized, non-interruption transmission path switching method)
To provide.

[0008]

In the optical transmission apparatus of the present invention, the transmission information sequence to be switched is transmitted in parallel between the working optical transmission lines and the standby optical transmission lines to ensure synchronization of the reception information sequences before switching. The present invention is provided with a non-instantaneous transmission line switching means, and is characterized in that the following means are provided in order to solve the above-mentioned problem, and a system that does not affect the transmission capacity due to physical synchronization is adopted.

The information string phase difference detecting means detects the phase difference between the received information strings from the working and standby optical transmission lines on the receiving side.

The optical wavelength change control means generates an optical wavelength change signal adapted to the phase difference signal from the information sequence phase difference detection means on the transmission side.

The electro-optical conversion / optical wavelength changing means converts the electric signal of the transmission information string into an optical signal and changes the wavelength of the transmitted light in accordance with the optical wavelength change signal from the optical wavelength change control means.

The optical wavelength change control means generates an optical wavelength selection signal adapted to the phase difference signal from the information sequence phase difference detection means.

The optical wavelength selection / optical-electrical conversion means selects the wavelength of the received light in accordance with the optical wavelength selection signal from the optical wavelength selection control means and converts the optical signal into an electric signal of the reception information string.

[0014]

According to the optical transmission device of the present invention, by the above-mentioned means, the transmission information sequence to be switched is transmitted in parallel between the working and protection optical transmission lines, the phase difference between the reception information sequences is detected, and the phase difference is detected. Change the wavelength of the transmitted light on the transmitting side so that it becomes zero, or select the wavelength of the received light on the receiving side to secure the synchronization of each received information string, and then set the working optical transmission line to the standby optical transmission line. Switch to without interruption.

[0015]

1 is a block diagram of an optical transmission apparatus according to an embodiment of the present invention.
As described above, the multiplexer / conversion device 1, the long frame pattern inserting circuit 2, the transmission side transmission line changeover switch 3, the transmission side data link circuit 6, the working optical transmission line 7, the spare optical transmission line 8, and the optical-electrical converting means are used. 9, the receiving side transmission line change-over switch 10, the demultiplexing device 11, the long frame synchronizing circuit 12, and the receiving side data link circuit 14 correspond to those of the conventional example shown in FIG. Electricity-
The optical conversion / optical wavelength changing means 4 follows the optical wavelength change signal from the optical wavelength change control means 5 to transmit side transmission line changeover switch 3
The electrical signal of the parallel transmission information sequence 100 from is converted into an optical signal, the wavelength of the transmission light is changed, and the optical signal is sent to the working and standby optical transmission lines 7 and 8. The light wavelength change control means 5 is
The phase difference signal from the information string phase difference detecting means 13 is judged via the data link between the receiving side data link circuit 14 and the transmitting side data link circuit 6. An optical wavelength change signal having a voltage that changes the wavelength of each of the active and standby transmission lights by adapting to the phase advance or delay is generated. The information sequence phase difference detection means 13 compares the phases of the working long frame pulses 600 and 700 from the long frame synchronizing circuit 12 and generates a phase difference signal of a voltage proportional to the phase difference.

The optical transmission apparatus of the above embodiment physically secures the synchronization of the reception information sequences 200 and 300 by changing the wavelength of the transmission light between the working and standby optical transmission lines 7 and 8. Then, adopt the method of switching.

As shown in FIG. 2, the electro-optical conversion / optical wavelength changing means 4 is provided with a wavelength tunable light emitting element (for example, a wavelength tunable semiconductor laser) to convert an electrical signal into an optical signal in accordance with a control signal from the outside and transmit light. Change the wavelength of. First, the drive circuit converts the voltage signal of the transmission information string into an optical modulation current signal for driving the wavelength tunable semiconductor laser. On the other hand, the optical wavelength changing voltage signal is converted into an optical wavelength tunable control current signal which changes the oscillation wavelength of the wavelength tunable semiconductor laser. Then, the wavelength tunable semiconductor laser converts the light modulation current signal into an optical signal proportional to the light modulation current signal and changes the semiconductor refractive index of the wavelength tunable semiconductor laser according to the light wavelength tunable control current signal to change the oscillation wavelength of the transmitted light. Since the refractive index of the optical fiber in the optical transmission line differs according to the wavelength of the transmitted light, the propagation speed of the transmission information string will differ, and according to the optical wavelength change signal that adapts to the advance or retardation of the phase, the transmission light for each of the working and standby transmissions will change. If the wavelengths are adjusted, the phases of the received information sequences can be matched and the synchronization can be secured.

The physical synchronizing means in the above embodiment is shown in FIG.
As described above, the transmission side may be the same as that of the conventional example shown in FIG. 5, and only the reception side may secure the physical synchronization. The optical wavelength selection control means 15 determines the phase difference signal from the information sequence phase difference detection means 13. An optical wavelength selection means is generated which is adapted to the phase advance / retard and selects the wavelength of each of the working light and the spare received light. The optical wavelength selection / optical-electrical conversion means 9a selects the wavelength of the received light from each of the working and standby optical transmission lines 7 and 8 in accordance with the optical wavelength selection signal from the optical wavelength selection control means 15 to obtain a specific wavelength. The optical signals are converted into voltage signals of the reception information sequences 200 and 300, respectively, and the bit synchronization clocks 400 and 500 are also provided.
To play.

The optical transmission apparatus of the above embodiment physically secures the synchronization of the received information sequences 200 and 300 by selecting the wavelength of the received light between the working and standby optical transmission lines 7 and 8. Then, adopt the method of switching.

The optical wavelength selection / optical-electrical conversion means 9a is shown in FIG.
As shown in the figure, it is equipped with a wavelength selective light receiving element (for example, Fabry-Perot type, Mach-Zehnder type, grating type optical demultiplexer, etc.) and an optical-electrical conversion light receiving element (optical detector), and receives according to a control signal from the outside. The wavelength of light is selected and the optical signal is converted into an electrical signal. First, the optical demultiplexer selects a wavelength from the received light including a plurality of optical signals having different wavelengths in accordance with the optical wavelength selection signal to form an optical signal of a specific wavelength. Next, an optical detector converts an optical signal of a specific wavelength into a voltage signal of the received information string. Since the received light includes a plurality of optical signals having different wavelengths, synchronization can be ensured by selecting a specific wavelength so that the phase difference of the received information string becomes zero.

[0021]

As described above, the optical transmission apparatus of the present invention employs a physical synchronization-based non-instantaneous transmission line switching system by optical wavelength control. Therefore, a memory control logic requiring a storage capacity proportional to the transmission capacity is used. Compared with the dynamic synchronization method, there is an effect that the synchronization of each received information sequence can be secured between the working and protection optical transmission lines without affecting the transmission capacity.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an optical transmission device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of the electro-optical conversion / light wavelength changing means shown in FIG.

FIG. 3 is a functional block diagram of another embodiment showing the present invention.

FIG. 4 is a functional block diagram of the optical wavelength selection / optical-electrical conversion means shown in FIG.

FIG. 5 is a functional block diagram of a conventional optical transmission device.

FIG. 6 is a block diagram of a long frame pattern insertion circuit shown in FIG.

[Explanation of symbols]

 4 electrical-optical conversion / optical wavelength changing means 5 optical wavelength change control means 7 working optical transmission path 8 spare optical transmission path 9a optical wavelength selection / optical-electrical conversion means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical indication location H04J 3/00 Q 8843-5K H04L 1/22 4101-5K

Claims (2)

[Claims] 1. An optical transmission apparatus comprising a non-instantaneous transmission line switching means for transmitting transmission information sequences to be switched in parallel between respective working optical transmission lines and protection optical transmission lines, and switching after securing synchronization of each reception information sequence. In the above, the receiving side is provided with an information sequence phase difference detecting means for detecting the phase difference of the received information sequence from the working and standby optical transmission lines, and the transmitting side is provided with the phase difference signal from the information sequence phase difference detecting means. The optical wavelength change control means for generating an optical wavelength change signal adapted to the optical wavelength change control means, and according to the optical wavelength change signal from the optical wavelength change control means, converts the electric signal of the transmission information sequence into an optical signal and changes the wavelength of the transmitted light. An optical transmission device comprising: a changing electric-optical conversion / light wavelength changing means. 2. An optical wavelength selection control means for generating an optical wavelength selection signal adapted to the phase difference signal from the information sequence phase difference detection means, and the optical wavelength in addition to the information sequence phase difference detection means on the receiving side. An optical wavelength selection / optical-electrical conversion means for selecting a wavelength of received light according to an optical wavelength selection signal from the selection control means and converting the optical signal into an electric signal of the reception information string is provided. Item 1. The optical transmission device according to item 1.