JP3661728B2 - Parallel optical transmission equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a parallel optical transmission device used in an optical interconnection system.
[0002]
The optical interconnection technology is a wiring technology for high-speed and high-density mounting in a communication device or the like. An optical transmission device used in an optical interconnection system is composed of an optical transmission module, an optical reception module, and an optical fiber. The optical signal is converted into an optical signal by the optical transmission module, and the optical fiber as a transmission path is transmitted. Received by the optical receiving module, converted into an electrical signal and output. The parallel optical transmission device has a higher transmission speed and mounting density by making the optical transmission device multi-channel. Usually, a tape fiber is used as a multi-core optical fiber which is a transmission path of the parallel optical transmission apparatus.
[0003]
On the other hand, skew is a problem in parallel transmission. Skew is a variation in signal transmission delay between channels, and is quantitatively defined by the difference between the maximum delay value and the minimum delay value of all the transmission delay channels. The transmission rate and transmission distance of a parallel transmission system are often limited by the skew of all channels rather than the transmission rate and transmission distance of each channel. Therefore, skew management is an important issue in parallel transmission systems, and it is desirable to reduce it as much as possible.
[0004]
The total transmission delay of each channel is obtained by accumulating delays generated in various processes for each channel from when a signal is input to the optical transmission module to when the signal is output from the optical reception module. Therefore, the variation in transmission delay is caused by the variation between channels in the delay that occurs in the individual processes of transmission. For example, what is called a fiber skew is a difference between channels in the transmission delay of an optical signal caused by a tape fiber serving as a transmission path. Moreover, in the optical transmission module and the optical reception module of the parallel optical transmission apparatus, an IC pad with a narrow pitch and an input / output terminal with a wide pitch are connected by electric wiring, but the structure is efficiently formed on a small substrate. In order to achieve this, the wiring length of the electrical wiring is different for each channel, often resulting in a difference in transmission delay of the electrical signal.
[0005]
In the conventional parallel optical transmission apparatus, in order to reduce the skew, a method of reducing a variation in delay generated in each process of these transmissions, for example, a method using a tape fiber having a small fiber skew is used.
[0006]
However, the parallel optical transmission apparatus as described above has the following problems. That is, even if the delay variation that occurs in each process of transmission is reduced, the overall transmission delay variation in which these delays are accumulated generally results from the overlap of the delay variation that occurs in each individual process of transmission. It becomes larger than the delay variation that occurs in each process of transmission. This problem will be described below with reference to the drawings.
[0007]
FIG. 3 shows a parallel optical transmission apparatus 300 having 40 channels and a transmission distance of 100 m. The parallel optical transmission apparatus 300 includes an optical transmission module 301, an optical reception module 302, and tape fibers 303a, 303b, 303c, and 303d. FIG. 4 is a diagram illustrating an example of variation in transmission delay due to electrical wiring for each channel of the optical transmission module 301 or the optical reception module 302. As can be seen from this figure, the transmission delay is different between the channels, and each skew is about 125 ps (difference between the maximum value and the minimum value in FIG. 4). If this is doubled, the value of the electrical wiring skew of both the optical transmission module 301 and the optical reception module 302 is obtained, which is about 250 ps.
[0008]
The tape fibers 303a, 303b, 303c, and 303d are 10-channel GI-50 / 125 tape fibers with small fiber skew. FIG. 5 is a diagram showing an example of variation in transmission delay per unit distance of each channel of the tape fiber. From this figure, it can be seen that the fiber skew per unit distance is about 1.5 ps / m 2. Since the tape fibers 303a, 303b, 303c and 303d are 100.00 m in length, the fiber skew is about 150 ps.
[0009]
When the transmission delay due to the electrical wiring of the optical transmission module 301 of the parallel optical transmission device 300, the transmission delay due to the electrical wiring of the optical reception module 302, and the transmission delay due to the tape fibers 303a, 303b, 303c and 303d are superimposed, The variation in the delay is as shown in FIG. From this figure, the skew is about 300 ps, which is larger than the individual values of the electrical wiring skew or fiber skew.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and an object of the present invention is to provide a parallel optical transmission apparatus with reduced skew as a whole.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the parallel optical transmission device of the present invention has a plurality of optical transmission modules with built-in electric wiring, optical receiving modules with built-in electric wiring, and a plurality of connecting these optical transmitting modules and optical receiving modules. In a parallel optical transmission device that transmits a multi-channel signal by forming a multi-channel parallel transmission path between the modules,
The lengths of the tape fibers are different from each other so that the sum of the transmission delay amount due to the electrical wiring of the optical transmission module and the optical reception module and the transmission delay due to the tape fiber becomes uniform between channels. To do.
[0012]
In addition, another parallel optical transmission apparatus of the present invention provides the above-mentioned all channels including the transmission delay of the transmitted signal due to the electrical wiring of the optical transmission module, the transmission delay due to the electrical wiring of the optical reception module, and the transmission delay due to the tape fiber. The difference between the maximum value and the minimum value is the sum of the transmission delay due to the electrical wiring of the optical transmitter module and the transmission delay due to the electrical wiring of the optical receiver module, and the maximum value and the minimum of all the channels. Or the length of each tape fiber and the individual tape fiber so that the transmission delay due to the tape fiber is smaller than the difference between the maximum value and the minimum value of all the channels. The transmission delay value of each individual channel is set.
[0013]
In such a parallel optical transmission apparatus of the present invention, there are variations in transmission delay due to the electrical wiring of the optical transmission module, variations in transmission delay due to the electrical wiring of the optical receiving module, and variations in transmission delay due to the tape fiber. However, by reducing the variation in the sum of the transmission delay due to the electrical wiring of the optical transmission module, the transmission delay due to the electrical wiring of the optical reception module, and the transmission delay due to the tape fiber for each channel, Variation in transmission delay can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0015]
[Example 1]
FIG. 1 is a diagram for explaining a first embodiment of the present invention. 100 is a parallel optical transmission device with 40 channels and a transmission distance of 100 m. The parallel optical transmission device 100 includes an optical transmission module 101, an optical reception module 102, and tape fibers 103a, 103b, 103c, and 103d. Further, the transmission delay due to the electrical wiring of each channel of the optical transmission module 101 or the optical reception module 102 is as shown in FIG. 4, and each skew is about 125 ps. The value of the electrical wiring skew of both the optical transmission module 101 and the optical reception module 102 is about 250 ps in total.
[0016]
The tape fibers 103a, 103b, 103c, and 103d are 10-channel GI-50 / 125 tape fibers. The variation in transmission delay per unit distance of each channel of the tape fiber is as shown in FIG. 5, and the fiber skew per unit distance is about 1.5 ps / m 2. The lengths of these tape fibers are adjusted to 100.02 m for the tape fibers 103a and 103d, 100.00 m for the 103b and 103c, and the fiber skew is about 150 ps, respectively.
[0017]
When the transmission delay due to the electrical wiring of the optical transmission module 101 of the parallel optical transmission device 100, the transmission delay due to the electrical wiring of the optical reception module 102, and the transmission delay due to the tape fibers 103a, 103b, 103c and 103d are superimposed, The variation in the delay is as shown in FIG. From this figure, it can be seen that the skew is about 250 ps, which is not larger than the electrical wiring skew, and that the overall skew is reduced as compared with the conventional example shown in FIG.
[0018]
[Example 2]
FIG. 2 is a diagram for explaining a second embodiment of the present invention. Reference numeral 200 denotes a parallel optical transmission device having 40 channels and a transmission distance of 100 m. The parallel optical transmission apparatus 200 includes an optical transmission module 201, an optical reception module 202, and tape fibers 203a, 203b, 203c, and 203d. Further, the transmission delay due to the electrical wiring of each channel of the optical transmission module 201 or the optical reception module 202 is as shown in FIG. 4, and each skew is about 125 ps. The electrical wiring skew value of both the optical transmission module 201 and the optical reception module 202 is about 250 ps in total.
[0019]
Tape fibers 203a, 203b, 203c and 203d are 10-channel GI-50 / 125 tape fibers. Among these, the variation in transmission delay per unit distance of each channel of the tape fibers 203b and 203c is as shown in FIG. 5, and the fiber skew per unit distance is about 1.5 ps / m 2. On the other hand, the transmission delay value per unit distance of each channel of the tape fibers 203a and 203d is adjusted to be distributed linearly as shown in FIG. 8, and the fiber skew per unit distance is about 2.5 ps / s. m. The lengths of these tape fibers are adjusted to 100.02m for the tape fibers 203a and 203d, 100.00m for the 203b and 203c, and the fiber skew is about 150 ps for the tape fibers 203b and 203c, and the tape fibers 203a and 203d. Is about 250ps.
[0020]
When the transmission delay due to the electrical wiring of the optical transmission module 201 of the parallel optical transmission device 200, the transmission delay due to the electrical wiring of the optical reception module 202, and the transmission delay due to the tape fibers 203a, 203b, 203c and 203d are superimposed, The variation in the delay is as shown in FIG. From this figure, the skew is about 150 ps, which is smaller than the electrical wiring skew or the fiber skew, and the overall skew is reduced as compared with the conventional example shown in FIG. 6 and the first embodiment shown in FIG. I understand that.
[0021]
In the above description, the embodiments of the present invention have been described. However, the present invention is not limited thereto. For example, the tape fiber may be divided in the length direction and connected by an optical fiber connector. Needless to say, the number of channels is not limited to 40.
[0022]
【The invention's effect】
According to the present invention, in the parallel optical transmission apparatus, the variation in the sum of the transmission delay due to the electrical wiring of the optical transmission module, the transmission delay due to the electrical wiring of the optical reception module, and the transmission delay due to the tape fiber is reduced, and the entire parallel optical transmission apparatus As a result, the skew can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment of a parallel optical transmission apparatus according to the present invention;
FIG. 2 is a diagram for explaining a second embodiment of a parallel optical transmission apparatus according to the present invention;
FIG. 3 is a diagram illustrating an example of a conventional parallel optical transmission apparatus.
FIG. 4 is a diagram illustrating an example of variation in transmission delay due to electrical wiring for each channel of the optical transmission module or the optical reception module.
FIG. 5 is a diagram showing an example of variation in transmission delay per unit distance of each channel of a 10-fiber tape fiber.
FIG. 6 is a diagram illustrating an example of variation in delay between channels in a conventional parallel optical transmission apparatus.
FIG. 7 is a diagram showing an example of delay variation between channels in the first embodiment of the parallel optical transmission apparatus according to the present invention;
FIG. 8 is a diagram showing an example of variations in transmission delay per unit distance of each channel of a 10-fiber tape fiber used in the second embodiment of the parallel optical transmission apparatus according to the present invention.
FIG. 9 is a diagram showing an example of variation in delay between channels in the second embodiment of the parallel optical transmission apparatus according to the present invention;
[Explanation of symbols]
100, 200, 300 Parallel optical transmission devices 101, 201, 301 Optical transmission modules 102, 202, 302 Optical reception modules 103, 203, 303 Tape fiber

Claims (1)

An optical transmission module incorporating electric wiring, an optical receiving module incorporating electric wiring, and a plurality of tape fibers connecting the optical transmission module and the optical receiving module, and a multi-channel parallel transmission path between the modules In a parallel optical transmission device that forms and transmits multi-channel signals,
When the transmission delay amount due to the electrical wiring of the optical transmitter module and the optical receiver module has a characteristic that the central portion of the multi-channel is substantially flat at the center and decreases toward the end of the channel in a substantially straight line,
The length of the tape fiber constituting the channel end portion where the transmission delay amount due to the electrical wiring decreases substantially linearly, and the length of the tape fiber constituting the center portion of the channel where the characteristics of the transmission delay amount due to the electrical wiring are substantially flat. Set longer than
As the tape fiber to be applied to the end of the channel where the transmission delay amount due to the electrical wiring decreases substantially linearly, a tape fiber adjusted so that the transmission delay amount between the channels changes substantially linearly with respect to the channel. The channel is combined by reversing the slope of the transmission delay amount due to the electrical wiring with respect to the channel and the slope of the transmission delay amount due to the tape fiber with respect to the channel, thereby compensating for variations in the sum of the transmission delay amounts between the channels. Parallel optical transmission equipment.

Images