JP2008015142A - Optical fiber coupler for wavelength multiplexing/demultiplexing, optical wavelength multiplex communication network, and method of adding wavelength in use in optical wavelength multiplex communication network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a WDM filter which can flexibly allocate an inexpensive and low-loss new wavelength based upon a standardized wavelength arrangement when adding a service. <P>SOLUTION: In a first wavelength multiplexing/demultiplexing optical fiber coupler, one end has one port and the other end has two ports, wherein the center wavelength of a transmitting wavelength band in one port on the other end includes 1,310 nm, 1,430 nm, 1,550 nm and approximately 1,670 nm and in the other port on the other end, 1,370 nm, 1,490 nm and approximately 1,610 nm. To the one port on the other end of this first optical fiber coupler, there is connected one port on one end of a second wavelength multiplexing/demultiplexing optical fiber coupler in which one end has one port and the other end has two ports, wherein the center wavelength of a transmitting wavelength band in one port on the other end includes approximately 1,310 nm and in the other port, approximately 1,550 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical fiber coupler for wavelength multiplexing / demultiplexing suitable for optical communication, in particular, optical wavelength (division) multiplexing communication, an optical wavelength multiplexing communication network using the same, and a method of adding a wavelength to be used.

  Currently, with the aim of introducing it into an access system, research on an optical wavelength multiplexing communication system between a single point such as B-PON (ATM-PON) and multiple points (point-to-multipoint) is in progress.

  FIG. 1 shows an example of a point-to-multipoint optical wavelength multiplex communication network. In the figure, 1 is a communication station, 2 is a plurality of user homes (only one is shown here), and 3 is a communication. An optical fiber transmission line disposed between the station 1 and each user home 2, and the optical fiber transmission line 3 is connected to each user home 2 by an optical power splitter 4 installed in the middle thereof. The branches are equally distributable.

  In the B-PON system, a wavelength near 1490 nm is used as a light source wavelength of a transmitter (not shown) included in the B-PON OLT 11 installed on the communication station 1 side in order to perform telephone and high-speed Internet communication services. A wavelength near 1310 nm is used as a light source wavelength of a transmitter (not shown) included in the B-PON ONU 12 installed on each user home 2 side.

  Here, a wavelength 1550 nm is added as a wavelength for video signal transmission (distribution) using optical wavelength division multiplexing (WDM) technology, that is, a wavelength near 1310 nm and near 1490 nm and a wavelength near 1550 nm are multiplexed / demultiplexed. By providing 13 and 14 on the communication station 1 side and each user home 2 side, respectively, one video signal transmission transmission device (V-OLT) 15 installed on the communication station 1 side is provided on each user home 2 side. The same video signal can be distributed to the installed video signal transmission device (V-ONU) 16, and this shared effect makes it possible to provide an economical service (prior art 1). In FIG. 1, the description of the test / monitoring wavelength of 1650 nm is omitted.

  The wavelength arrangement of signal light in the B-PON system is recommended by ITU-T G983.3 as standardization, and as shown in FIG. 2, the light source wavelength (up) of the user's home is 1260 to 1360 nm, the communication station side 1480-1500 nm as a light source wavelength (downstream), 1539-1565 nm as a wavelength for video signal transmission, and wavelength bands around 1400 nm and 1600 nm for future extended services. Furthermore, when testing / monitoring optical fiber transmission lines, the wavelength of 1650 nm among the wavelengths for test / monitoring specified by ITU-T, especially 1650 nm, is mounted with an OTDR (optical pulse tester). Most commonly used in systems.

  On the other hand, research and development of gigabit-class transmission capacity communication systems using optical media converters (optical MC) have progressed as point-to-point optical wavelength division multiplexing communication systems. Yes.

  FIG. 3 shows an example of a point-to-point optical wavelength division multiplexing network. In the figure, there are a plurality of 2-1, 2-2, 2-3, here three user homes, 3-1, 3 -2, 3-3 are three optical fiber transmission lines, 17-1, 17-2, 17-3 are three optical MCs provided on the communication station 1 side, 18-1, 18-2, 18 -3 is an optical MC provided on each of the user homes 2-1, 2-2, 2-3, and each optical MC 17-1, 17-2, 17-3 and each optical MC 18-1, 18-2. , 18-3 are connected to each other independently through optical fiber transmission lines 3-1, 3-2 and 3-3.

  In the optical MC, for example, 1000BASE-BX10 is defined as a 1 Gb / s Ethernet (registered trademark) standard that uses a single optical fiber, and its wavelength arrangement is the same as that of ITU-T G983.3. Two wavelengths of 1260 to 1360 nm are defined as the light source wavelength on the house side (upstream) and 1480 to 1500 nm as the light source wavelength (downstream) on the communication station side (prior art 2). In such a point-to-point communication method, one user can occupy the optical fiber transmission line and the transmission device on the communication station side, here the optical MC, so that a sufficient transmission band can be obtained. become.

  As for the access-related optical communication network technology described above, for example, Non-Patent Document 1 describes the entire technology in detail, and Non-Patent Document 2 describes the trend of standardization.

  On the other hand, a WDM optical fiber wavelength coupler is a kind of optical multiplexer / demultiplexer (WDM filter), which is manufactured by melting and stretching two single-mode optical fibers, and multiplexes and demultiplexes signal light of two different wavelengths. Used for. Compared to other WDM filters such as dielectric multilayers and small planar lightwave circuits (PLCs), it is a component composed of optical fibers, so it can be easily connected to optical fiber transmission lines, and has low loss and low It has the advantage of a price (about several thousand yen). On the other hand, although wavelength separation at a fine wavelength interval is somewhat difficult, the interval between the two wavelengths to be separated can be adjusted by the length of the stretched portion, and has already been adjusted for 980/1550 nm, 1310/1550 nm, 1480 / The product for 1550 nm is commercialized as a commercial product.

For example, in a WDM optical fiber wavelength coupler for 1480/1550 nm, the wavelength separation Δλ is 70 nm. At the research level, as shown in Non-Patent Document 3, an interval of 30 nm is realized as Δλ. Further, as shown in Non-Patent Document 3, it has been experimentally confirmed that the transmission wavelength band of the WDM optical fiber wavelength coupler has periodicity (transmittance characteristics periodically change on the wavelength axis). As shown in Non-Patent Document 4, the wavelength dependence of the coupling ratio (%) of each port can be well approximated by a sine function and a cosine function.
“FTTH Textbook” IDG Japan, 2003, pp. 115-154 IEICE Technical Report, OFT 2004-3, 2004, pp. 11-14 2000 IEICE General Conference, B-13-26 "Optical fiber and fiber type device" Baifukan, issued July 10, 1996, pp. 179-189

  However, the following problems are known in the point-to-multipoint optical wavelength multiplex communication network as shown in FIG. That is, since a large number of users share the transmission apparatus on the communication station side, here B-PON OLT and V-OLT, the transmission rate (transmission band) of signal light allocated per user is a relatively low value. . In addition, it is difficult to add or change a service to a specific user, upgrade a transmission rate, and the like, and in order to implement this, it may be necessary to temporarily interrupt service provision to other users.

  On the other hand, in the point-to-point optical wavelength multiplex communication network as shown in FIG. 3, one user can occupy the optical fiber transmission line and the transmission device on the communication station side. Transmission band) can be obtained. Further, since the wavelength band near 1550 nm is not used as a transmission wavelength, it is theoretically possible to add a wavelength of 1550 nm as a wavelength for video signal transmission using a WDM filter. However, the type and configuration technology of the WDM filter used at this time have not been established at present.

  Further, not only video signals but also the addition of a wavelength of about 1650 nm (wavelength 1, wavelength 2) is assumed in order to cope with the addition of a test / monitoring wavelength of 1650 nm and further increase in demand for new services in the future. As the network configuration, for example, a configuration as shown in FIG. 4 or 5 is conceivable.

  FIG. 4 shows an example in which a wavelength for test / monitoring is added by an optical branching module, and a new wavelength 1 and wavelength 2 are added together with a wavelength for video signal transmission by a WDM filter and a splitter for splitting optical power two. Is shown. That is, in FIG. 4, 19 is a well-known OTDR, which is connected to the optical fiber transmission line 3 through the optical branching module 20, and is used to input / output test / monitoring signal light having a wavelength of 1650 nm. Reference numerals 21 and 22 denote transmitters whose wavelengths of the transmission signal light are the wavelength 1 and wavelength 2 and are connected to the optical fiber transmission line 3 through the WDM filter 23 and the optical power bifurcation splitter 24 together with the V-OLT 15. Thus, transmission signal light having a wavelength of 1550 nm, a wavelength of 1 and a wavelength of 2 for video signal transmission is input.

  FIG. 5 shows an example in which a video signal transmission wavelength, a new wavelength 1 and a wavelength 2 are added using a WDM filter and a splitter for splitting optical power, including wavelengths for testing and monitoring. The OTDR 19, V-OLT 15, and transmitters 21 and 22 are connected to the optical fiber transmission line 3 through the WDM filter 25 and the optical power bifurcation splitter 24, and input / output signal light for testing and monitoring with a wavelength of 1650 nm. In addition, a signal light for transmitting a video signal having a wavelength of 1550 nm and a transmission signal light having a wavelength of 1 and a wavelength of 2 are input.

  4 and 5, the insertion loss of the optical branching module 20 generally reaches about 2 to 3 dB in the wavelength range (1260 to 1625 nm) of communication signal light. Further, the insertion loss of the splitter for splitting optical power 24 is also about 3 dB, and in addition to this, the WDM filter 23 or 25 is further required. The WDM filter 23 is for combining the signal light for the video signal having the wavelength of 1550 nm and the signal light having the wavelength of 1 and 2, and the WDM filter 25 is additionally used for the test / wavelength of 1650 nm. This is for multiplexing and demultiplexing the monitoring signal light.

  4 and 5, the optical MC 17 on the communication station 1 side includes a transmitter (light source) 26 having one wavelength near 1490 nm as the wavelength of the transmitted signal light, and one wavelength near 1310 nm as the wavelength of the received signal light. And a WDM filter 28 for multiplexing and demultiplexing the upstream and downstream signal lights, and a test / monitoring signal light having a wavelength of 1650 nm on the user home 2 side. A filter 29 for cutting off is mounted (both are not shown in FIG. 3). Although not shown, the light MC 18 on the user home 2 side corresponds to the light MC 17 on the communication station 1 side, and is a transmitter (light source) having a wavelength near 1310 nm as the wavelength of the transmission signal light. A WDM filter for multiplexing and demultiplexing the upstream and downstream signal light is mounted together with a receiver that uses one wavelength as the wavelength of the received signal light.

  Therefore, as the test / monitoring wavelength and the new service wavelength are added from the configuration of FIG. 3, although depending on the components and method of the network, considering only the communication station side, A new loss exceeding 5 dB is added to the signal light (actually, a loss due to addition / change of the WDM filter on the user's home side is further added). This places a heavy burden on the light source and the receiver, and with the increase in the cost of the light source and the receiver, in the worst case, failure due to deterioration of transmission characteristics and provision of service may be impossible.

  Also, using a dielectric multilayer film, etc., a WDM filter having all possible wavelengths (about 6 wavelengths) in the transmission region is produced and mounted from the beginning in all optical MCs on the communication station side. However, in reality, the number of wavelengths used (service count and transmission speed) varies from user to user, so all multi-wavelength WDM filters such as relatively expensive dielectric multilayers can be used. It is obviously disadvantageous to mount on the optical MC from the viewpoint of economy. In addition, in the case of a dielectric multilayer filter or the like, the insertion loss increases as the number of wavelengths used increases, so although it is expected to be less than the configuration of FIG. 4 or FIG. 5, it becomes a burden on the light source and the receiver, This may cause deterioration of transmission characteristics (shortening of transmission distance).

  As described above, in a point-to-point communication system, there is an advantage that a sufficient transmission band can be secured, but at the same time, it is inexpensive and has a low loss, and a WDM filter that flexibly realizes allocation of a new wavelength as a service is added. The lack of technology has become a problem when adding new services such as video signals. In this case, it is naturally desirable that the wavelength allocated to each service conforms to the standardized wavelength arrangement shown in FIG. 2 from the viewpoint of economics of the light source and the WDM filter.

  In view of the above-described problems, the present invention provides a WDM filter that is inexpensive and has low loss, and that can flexibly realize a new wavelength allocation that conforms to a standardized wavelength arrangement associated with service addition, and uses the WDM filter. Can easily add or change a service to a specific user, upgrade a transmission speed, and the like, and can secure a sufficient transmission band for each user, and a method of adding a wavelength to be used The purpose is to provide.

  1st invention which solves the subject mentioned above is for wavelength multiplexing / demultiplexing which has the transmittance characteristic which changes periodically on a wavelength axis, and has one end side at least one port, and the other end side has two ports An optical fiber coupler for wavelength multiplexing / demultiplexing comprising at least two stages of optical fiber couplers, in addition to a first-stage wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band with an interval of 60 nm (120 nm period) One end side of the second-stage wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band at 120 nm intervals (240 nm period) or 240 nm intervals (480 nm period) on at least one of the two end ports Or in addition to this, at least one of the two ports on the other end of the second-stage wavelength multiplexing / demultiplexing optical fiber coupler is connected to 240 nm. Characterized in that formed by connecting (480 nm period) one end of the port of the wavelength division optical fiber coupler of the third stage having a transmission wavelength band of.

  According to a second aspect of the present invention for solving the above-mentioned problem, in the optical fiber coupler for wavelength multiplexing / demultiplexing according to claim 1, of the two ports on the other end side of the optical fiber coupler for wavelength multiplexing / demultiplexing at the first stage. The center wavelength of the light transmission wavelength band at one of the ports includes 1310 nm, 1430 nm, 1550 nm, and 1670 nm, and the center wavelength of the light transmission wavelength band at the other port ranges from 1370 nm, 1490 nm, and 1610 nm. In the case where it is included, as the optical fiber coupler for wavelength multiplexing / demultiplexing after the second stage connected to the one port, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side is 1310 nm. 240 nm intervals (480 nm) including the vicinity and the center wavelength of the transmission wavelength band of light at the other port including the vicinity of 1550 nm In addition to this, at least a wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 2) is used, or in addition, as a second-stage wavelength multiplexing / demultiplexing optical fiber coupler connected to the other port The center wavelength of the light transmission wavelength band in one of the two ports on the end side includes the vicinity of 1490 nm, and the center wavelength of the light transmission wavelength band in the other port includes the vicinity of 1610 nm (120 nm interval) (240 nm period) It is characterized in that at least a wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of is used.

  A third invention for solving the above-described problem is an optical fiber transmission line disposed between a communication station and a user's home, and at least one communication station side that converts an input electric signal into signal light and transmits the signal light A transmitter on the communication station side, at least one receiver on the communication station side that converts the received signal light into an electrical signal, and at least one transmission signal light from the transmitter on the communication station side and the receiver on the communication station side Optical wavelength multiplexing / demultiplexing means on the communication station side that inputs / outputs at least one received signal light for each wavelength to / from one end of the optical fiber transmission line, and converts the input electrical signal to signal light At least one transmitter on the user's home side for transmission, at least one receiver on the user's home side for converting the received signal light into an electrical signal, and at least one transmission signal from the transmitter on the user home side Light and the user's home side Optical wavelength comprising at least user-side optical wavelength multiplexing / demultiplexing means for multiplexing and demultiplexing at least one received signal light to the receiver for each wavelength with respect to the other end of the optical fiber transmission line. In a multiplex communication network, the wavelength multiplexing / demultiplexing optical fiber coupler according to claim 1 or 2 is used as the optical wavelength multiplexing / demultiplexing means on the communication station side.

  A fourth invention that solves the above-described problem is an optical fiber transmission line disposed between a communication station and a user's home, and at least one communication station side that converts an input electric signal into signal light and transmits the signal light A transmitter on the communication station side, at least one receiver on the communication station side that converts the received signal light into an electrical signal, and at least one transmission signal light from the transmitter on the communication station side and the receiver on the communication station side Optical wavelength multiplexing / demultiplexing means on the communication station side that inputs / outputs at least one received signal light for each wavelength to / from one end of the optical fiber transmission line, and converts the input electrical signal to signal light At least one transmitter on the user's home side for transmission, at least one receiver on the user's home side for converting the received signal light into an electrical signal, and at least one transmission signal from the transmitter on the user home side Light and the user's home side Optical wavelength comprising at least user-side optical wavelength multiplexing / demultiplexing means for multiplexing and demultiplexing at least one received signal light to the receiver for each wavelength with respect to the other end of the optical fiber transmission line. In the multiplex communication network, the optical wavelength multiplexing / demultiplexing means on the communication station side has at least one port on one end side and two ports on the other end side, and the two ports on the other end side The center wavelength of the light transmission wavelength band at one of the ports includes the vicinity of 1310 nm, the vicinity of 1430 nm, the vicinity of 1550 nm, and the vicinity of 1670 nm, and the center wavelength of the transmission wavelength band of the light at the other port Including at least a first wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 60 nm intervals (120 nm period), In an optical wavelength division multiplexing communication network using one wavelength near 1490 nm as a wavelength of transmission signal light from a transmitter and one wavelength near 1310 nm as a wavelength of reception signal light to one receiver on the communication station side In the method of adding a wavelength to be used, one end side has at least one port, the other end side has two ports, and the center wavelength of the light transmission wavelength band in one of the two ports on the other end side One end side of the second wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including the vicinity of 1310 nm and the center wavelength of the transmission wavelength band of light at the other port including the vicinity of 1550 nm Is connected to one port on the other end side of the first wavelength multiplexing / demultiplexing optical fiber coupler, and the second wavelength multiplexing / demultiplexing optical fiber coupler For outputting a received signal light from one of the two ports on the other end side to one receiver on the communication station side, and for transmitting a video signal having at least one wavelength near 1550 nm to the other port The signal light is input.

  A fifth invention that solves the above-described problem is an optical fiber transmission line disposed between a communication station and a user's home, and at least one communication station side that converts an input electric signal into signal light and transmits the signal light A transmitter on the communication station side, at least one receiver on the communication station side that converts the received signal light into an electrical signal, and at least one transmission signal light from the transmitter on the communication station side and the receiver on the communication station side Optical wavelength multiplexing / demultiplexing means on the communication station side that inputs / outputs at least one received signal light for each wavelength to / from one end of the optical fiber transmission line, and converts the input electrical signal to signal light At least one transmitter on the user's home side for transmission, at least one receiver on the user's home side for converting the received signal light into an electrical signal, and at least one transmission signal from the transmitter on the user home side Light and the user's home side Optical wavelength comprising at least user-side optical wavelength multiplexing / demultiplexing means for multiplexing and demultiplexing at least one received signal light to the receiver for each wavelength with respect to the other end of the optical fiber transmission line. In the multiplex communication network, the optical wavelength multiplexing / demultiplexing means on the communication station side has at least one port on one end side and two ports on the other end side, and the two ports on the other end side The center wavelength of the light transmission wavelength band at one of the ports includes 1310 nm, 1430 nm, 1550 nm, and 1670 nm, and the center wavelength of the light transmission wavelength band at the other port ranges from 1370 nm, 1490 nm, and 1610 nm. Including at least a first wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 60 nm intervals (120 nm period), In an optical wavelength division multiplexing communication network using one wavelength near 1490 nm as a wavelength of transmission signal light from a transmitter and one wavelength near 1310 nm as a wavelength of reception signal light to one receiver on the communication station side In the method of adding a wavelength to be used, one end side has at least one port, the other end side has two ports, and the center wavelength of the light transmission wavelength band in one of the two ports on the other end side For the second wavelength multiplexing / demultiplexing including transmission wavelength bands of 120 nm intervals (240 nm period) including the vicinity of 1310 nm and the vicinity of 1550 nm, and the center wavelength of the transmission wavelength band of light at the other port includes the vicinity of 1430 nm and the vicinity of 1670 nm. A port on one end of the optical fiber coupler is connected to one port on the other end of the first optical fiber coupler for wavelength multiplexing / demultiplexing. The one end side has at least one port, the other end side has two ports, and the center wavelength of the transmission wavelength band of light in one of the two ports on the other end side includes around 1310 nm, A port on one end side of a third wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including a center wavelength of light transmission wavelength band in the other port in the vicinity of 1550 nm, And connected to one port on the other end side of the second wavelength multiplexing / demultiplexing optical fiber coupler, via the other port of the two ports on the other end side of the second wavelength multiplexing / demultiplexing optical fiber coupler. Signal light for testing and monitoring an optical fiber transmission line having one wavelength near 1650 nm is input / output, and one of two ports on the other end side of the third wavelength multiplexing / demultiplexing optical fiber coupler is input / output. Port Together to output the received signal light to the one receiver of the communication station, characterized by inputting a signal light for transmission video signal consisting of at least one wavelength of 1550nm near the other port.

According to a sixth invention for solving the above-described problem, in the method for adding a wavelength to be used in an optical wavelength division multiplexing network according to claim 5, in addition to the above, one end side has at least one port, and the other end side has two A center wavelength of a light transmission wavelength band in one of the two ports on the other end side includes a vicinity of 1490 nm, and a center wavelength of a light transmission wavelength band in the other port near 1370 nm; A port on one end side of the fourth wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 120 nm interval (240 nm period) including the vicinity of 1610 nm is connected to the other end of the first wavelength multiplexing / demultiplexing optical fiber coupler. Connect to the other port on the side,
The one end side has at least one port, the other end side has two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1430 nm, A port on one end side of a fifth wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including a central wavelength of light transmission wavelength band in the vicinity of 1670 nm. To the other port on the other end side of the wavelength multiplexing / demultiplexing optical fiber coupler, and the communication from one of the two ports on the other end side of the third wavelength multiplexing / demultiplexing optical fiber coupler. A signal light for video signal transmission consisting of at least one wavelength near 1550 nm is inputted to the other port while receiving the signal light to one receiver on the station side, and the fourth wavelength multiplexing / demultiplexing Transmission signal light from one transmitter on the communication station side is input to one of the two ports on the other end side of the optical fiber coupler, and other than the fifth wavelength multiplexing / demultiplexing optical fiber coupler. Signal light for test / monitoring of an optical fiber transmission line composed of one wavelength near 1650 nm is input / output via the other of the two ports on the end side, and further for the fourth wavelength multiplexing / demultiplexing Transmit signal light from another transmitter on the communication station side having one wavelength near 1610 nm is input to the other port of the two ports on the other end side of the optical fiber coupler, or the fifth wavelength combining The transmission signal light from the other transmitter on the communication station side having one wavelength near 1430 nm is input to one of the two ports on the other end side of the optical fiber coupler for waves, or the fourth Optical fiber for wavelength multiplexing / demultiplexing Transmission signal light from another transmitter on the communication station side having one wavelength near 1610 nm is input to the other of the two ports on the other end side of the coupler, and the fifth wavelength multiplexing / demultiplexing Transmission signal light from another transmitter on the communication station side having one wavelength near 1430 nm is input to one of the two ports on the other end side of the optical fiber coupler.

  The optical fiber coupler for wavelength multiplexing / demultiplexing (WDM optical fiber wavelength coupler) according to the present invention has an advantage of low cost and low loss because the optical fiber parts having the same shape and structure are fused and connected in multiple stages. . In addition, since the transmission wavelength band of the wavelength multiplexing / demultiplexing optical fiber coupler has periodicity, by setting the transmission wavelength interval appropriately, a transmission wavelength band conforming to the standardized wavelength arrangement can be realized for each port. Can do. Furthermore, by using the optical fiber coupler for wavelength multiplexing / demultiplexing of the present invention in a point-to-point optical wavelength division multiplexing communication network, particularly a transmission apparatus on the communication station side, addition or change of service to a specific user, It is possible to realize an optical wavelength division multiplexing network having a flexible structure and a method for adding a wavelength to be used, which can easily upgrade a transmission rate and secure a sufficient transmission band for each user.

  Hereinafter, a wavelength multiplexing / demultiplexing optical fiber coupler according to the best mode of the present invention, an optical wavelength division multiplexing communication network using the same, and a method of adding a wavelength to be used will be specifically described with reference to the drawings.

  FIG. 6 shows basic components of the optical fiber coupler for wavelength multiplexing / demultiplexing according to the present invention, here, a well-known 2 × 2 WDM optical fiber wavelength coupler (one for wavelength multiplexing / demultiplexing) having two ports on one end side and multi-end side. Fiber coupler), for example 31, is shown.

  The 2 × 2 WDM optical fiber wavelength coupler 31 is manufactured by melt-drawing a single mode optical fiber such as SMF as described in the background art section, and its extension length is 60 nm intervals (120 nm period). A transmission wavelength band, one of the two ports on the other end side, for example, including the vicinity of 1310 nm as the center wavelength of the light transmission wavelength band in A, and the other port, for example, the light transmission wavelength band in B The center wavelength is adjusted to include around 1490 nm.

  Therefore, the center wavelength of the transmission wavelength band of port A is around 1310 nm, around 1430 nm, around 1550 nm, and around 1670 nm within the operating wavelength range of the 1.3 μm zero dispersion single mode fiber (SMF) used for the optical fiber transmission line. The center wavelength of the transmission wavelength band of port B includes 1370 nm, 1490 nm, and 1610 nm. The downstream signal light wavelength is 1490 nm, and the upstream signal light wavelength is 1310 nm. If selected, it can be used as a WDM filter for optical MC on the communication station 1 side shown in FIGS. At this time, any one port on one end side is connected to the optical fiber transmission line, and each port on the other end side is connected to a light source (transmitter) and a receiver in the optical MC.

  The wavelength band in which the amount of decrease in the coupling efficiency of this coupler is within 0.5 dB covers a range of ± 10 nm or more from the center wavelength. Accordingly, for example, in CWDM (Coarse-WDM), a wavelength grid with a spacing of 20 nm is defined, so that a DFB-LD light source for CWDM without temperature control, which is rapidly becoming cost-reduced, is connected to the communication station side and the user's home. It can be used as a light source (transmitter) in the side light MC. In addition, the present coupler may be mounted inside the optical MC or installed outside. Furthermore, as an additional wavelength conforming to the standardized wavelength arrangement shown in FIG. In that case, a WDM filter (PLC or the like) for multiplexing / demultiplexing the wavelength is newly inserted between the light source or receiver of the wavelength and the ports A and B, or described in the following embodiments. Thus, a low-loss filter configuration can be realized by adding a 2 × 2 WDM optical fiber wavelength coupler with 120 nm intervals (240 nm period) or 240 nm intervals (480 nm period).

<Embodiment 1>
FIG. 7 shows a first embodiment of the wavelength multiplexing / demultiplexing optical fiber coupler of the present invention, in this case, in addition to the wavelength of upstream signal light in the vicinity of 1310 nm, the wavelength of downstream signal light in the vicinity of 1490 nm, An example is shown in which the wavelength of signal light for video signal transmission in the vicinity of 1550 nm can be multiplexed and demultiplexed.

  In the optical fiber coupler for wavelength multiplexing / demultiplexing according to the present embodiment, for example, 5, a similar 2 × 2 WDM optical fiber wavelength coupler, for example, 32 is added after the 2 × 2 WDM optical fiber wavelength coupler 31 shown in FIG. Is.

  More specifically, one end side and the multi-end side each have two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1310 nm, and the other port A port on one end side of the 2 × 2 WDM optical fiber wavelength coupler 32 having a transmission wavelength band of 240 nm intervals (480 m period) including the central wavelength of the light transmission wavelength band in the vicinity of 1550 nm is defined as 2 × 2 WDM. The optical fiber wavelength coupler 31 is connected to one port on the other end side, that is, A.

  The coupling efficiency (dB) of the ports P1 (1310 nm), P2 (1490 nm), and P3 (1550 nm) on the other end side of the coupler 5 is as shown in FIG. At the current level of commercial fiber optic coupler fabrication technology, an insertion loss at the center wavelength of each port can be sufficiently fabricated within about 0.5 dB. In addition, for each of the ports P1, P2, and P3, the wavelength band in which the reduction in coupling efficiency is within 0.5 dB is in the range of ± 10 nm or more from the center wavelength, and if the reduction is in the wavelength band of 1 dB, ± 15 nm or more is secured. it can. Therefore, a low insertion loss of about 1 dB can be realized in the wavelength range 1539 to 1565 nm of the video signal. Further, the crosstalk between the upstream signal light (1480 to 1500 nm) and the video signal transmission signal light (1539 to 1565 nm) to the port P1 can be about 15 dB or more.

<Embodiment 2>
FIG. 9 shows a second embodiment of the optical fiber coupler for wavelength multiplexing / demultiplexing according to the present invention, here, in addition to the wavelength of upstream signal light in the vicinity of 1310 nm, the wavelength of downstream signal light in the vicinity of 1490 nm, An example in which the wavelength of signal light for video signal transmission in the vicinity of 1550 nm and the wavelength of signal light for test and monitoring in the vicinity of 1650 nm can be multiplexed / demultiplexed is shown.

  In the optical fiber coupler for wavelength multiplexing / demultiplexing of the present embodiment, for example, 6, a similar 2 × 2 WDM optical fiber wavelength coupler, for example, 33 is added after the 2 × 2 WDM optical fiber wavelength coupler 31 shown in FIG. Further, the 2 × 2 WDM optical fiber wavelength coupler 32 shown in FIG. 7 is added to the subsequent stage.

  More specifically, the one end side and the multi-end side each have two ports, and the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1310 nm and the vicinity of 1550 nm, The one end side of the 2 × 2 WDM optical fiber wavelength coupler 33 having a transmission wavelength band of 120 nm intervals (240 m period) including the vicinity of 1430 nm and the vicinity of 1670 nm as the center wavelength of the transmission wavelength band of light at the port of (1) The port is connected to one port on the other end side of the 2 × 2 WDM optical fiber wavelength coupler 31, that is, A, and the port on one end side of the 2 × 2 WDM optical fiber wavelength coupler 32 is connected to the 2 The × 2 WDM optical fiber wavelength coupler 33 is connected to one port on the other end side.

  The coupling efficiencies (dB) of the ports P1 (1310 nm), P2 (1490 nm), P3 (1550 nm), and P4 (1670 nm) on the other end side of the coupler 6 are as shown in FIG. At the current level of commercial fiber optic coupler fabrication technology, an insertion loss at the center wavelength of each port can be sufficiently fabricated within about 0.5 dB. In addition, for each of the ports P1, P2, and P3, the wavelength band in which the reduction in coupling efficiency is within 0.5 dB is in the range of ± 10 nm or more from the center wavelength, and if the reduction is in the wavelength band of 1 dB, ± 15 nm or more is secured. it can. Therefore, a low insertion loss of about 1 dB can be realized in the wavelength range 1539 to 1565 nm of the video signal.

  Further, the crosstalk between the upstream signal light (1480 to 1500 nm) and the video signal transmission signal light (1539 to 1565 nm) to the port P1 can be about 15 dB or more. As for the port P4, the decrease in coupling efficiency is about 1.5 dB at the standard wavelength of 1650 nm for testing and monitoring, but the 1650 nm wavelength is not input to the optical fiber transmission line for communication. Considering that it is used for regular OTDR tests, it is a level that is completely satisfactory.

<Embodiment 3>
FIG. 11 shows a third embodiment of the optical fiber coupler for wavelength multiplexing / demultiplexing according to the present invention, here, in addition to the wavelength of upstream signal light in the vicinity of 1310 nm, the wavelength of downstream signal light in the vicinity of 1490 nm, An example in which the wavelength of signal light for video signal transmission in the vicinity of 1550 nm, the wavelength of signal light for test and monitoring in the vicinity of 1650 nm, and the wavelength of new signal light for service in the vicinity of 1610 nm and 1430 nm can be multiplexed / demultiplexed. Indicates.

  The wavelength multiplexing / demultiplexing optical fiber coupler according to the present embodiment, for example, 7 is the same 2 × 2 wavelength optical fiber coupler 6 shown in FIG. A 2WDM optical fiber wavelength coupler is further added, and a similar 2 × 2 WDM optical fiber wavelength coupler, for example, 35 is further added after the 2 × 2 WDM optical fiber wavelength coupler 33.

  More specifically, the one end side and the multi-end side each have two ports, and the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1490 nm, A port on one end side of the 2 × 2 WDM optical fiber wavelength coupler 34 having a transmission wavelength band of 120 nm intervals (240 m period) including the central wavelength of the transmission wavelength band of light including the vicinity of 1370 nm and the vicinity of 1610 nm, Connected to the other port on the other end side of the 2 × 2 WDM optical fiber wavelength coupler 31, that is, B, one end side and the multi-end side each have two ports, and one of the two ports on the other end side The center wavelength of the light transmission wavelength band includes the vicinity of 1430 nm, and the center wavelength of the light transmission wavelength band of the other port includes the vicinity of 1670 nm. A port on one end side of the 2 × 2 WDM optical fiber wavelength coupler 35 having a transmission wavelength band of 40 nm intervals (480 nm period) is designated as the other port on the other end side of the 2 × 2 WDM optical fiber wavelength coupler 33. Is connected to.

  The coupling efficiency (dB) of each port P1 (1310 nm), P2 (1490 nm), P3 (1550 nm), P4 (1670 nm), P5 (1610 nm), and P6 (1430 nm) on the other end side in this coupler is shown in FIG. It becomes like this. At the current level of commercial fiber optic coupler fabrication technology, an insertion loss at the center wavelength of each port can be sufficiently fabricated within about 0.5 dB. Further, for each of the ports P1, P2, P3, P5, and P6, the wavelength band in which the reduction amount of the coupling efficiency is within 0.5 dB is in the range of ± 10 nm or more from the center wavelength, and if the reduction amount is a wavelength band of 1 dB, ± 15 nm or more can be secured. Therefore, a low insertion loss of about 1 dB can be realized in the wavelength range 1539 to 1565 nm of the video signal.

  Further, the upstream signal light (1480 to 1500 nm), the video signal transmission signal light (1539 to 1565 nm), and the wavelength 1 of the signal light for additional service (assuming 1600 to 1620 nm) to the port P1 The crosstalk with the wavelength 2 (assuming 1420 to 1440 m) of the signal light for additional service can be about 15 dB or more. As for the port P4, the decrease in coupling efficiency is about 1.5 dB at the standard wavelength of 1650 nm for testing and monitoring, but the 1650 nm wavelength is not input to the optical fiber transmission line for communication. Considering that it is used for regular OTDR tests, it is a level that is completely satisfactory.

  Note that the 2 × 2 WDM optical fiber wavelength coupler itself is inexpensive, and the 2 × 2 WDM optical fiber wavelength coupler used in the present invention is limited to the 60 nm interval, 120 nm interval, and 240 nm interval, which have already been established in the fabrication technology. Even if the optical fiber couplers for wavelength multiplexing / demultiplexing having the configurations described in Embodiments 1 to 3 (FIGS. 7, 9, and 11) are arranged in all the optical MCs in the communication station from the beginning, the increase in cost is negligible. However, at first, the 2 × 2 WDM optical fiber wavelength coupler shown in FIG. 6 is used, and only a specific user is connected to the ports A and B after the ports A and B by 2 at 120 nm intervals and 240 nm intervals. A configuration of the first to third embodiments can be obtained by appropriately inserting a × 2 WDM optical fiber wavelength coupler.

<Embodiment 4>
FIG. 13 shows the first embodiment of the optical wavelength division multiplexing network and the method of adding the wavelength used according to the present invention. Here, two wavelengths near 1310 nm and 1490 nm, and near 1650 nm for test and monitoring are shown. In the optical wavelength division multiplexing communication network in which the wavelength is used, it is assumed that a new video signal transmission wavelength near 1550 nm is added. The communication station 1 already has a transmitter (light source) 26 that uses one wavelength near 1490 nm as the wavelength of the transmitted signal light, and a receiver 27 that uses one wavelength near 1310 nm as the wavelength of the received signal light. An optical MC 17 having a WDM filter composed of a 2 × 2 WDM optical fiber wavelength coupler shown in FIG. 6 for multiplexing and demultiplexing upstream and downstream signal light, and an optical fiber transmission line 3 via an optical branching module 20 It is assumed that a connected OTRD 19 is mounted.

  In such a case, as described in the first embodiment, one port on the other end side of the 2 × 2 WDM optical fiber wavelength coupler 31 shown in FIG. The optical fiber coupler 5 for wavelength multiplexing / demultiplexing shown in FIG. 7 as a whole is mounted in the optical MC 17 on the communication station 1 side, and the receiver 27 is connected to the port P1. Then, the transmitter 26 may be connected to the port P2, and the V-OLT 15 for video signal transmission may be connected to the port P3.

  As already described, the wavelength multiplexing / demultiplexing optical fiber coupler 5 shown in FIG. 7 can realize a low insertion loss of about 1 dB in the allocated wavelength range of the video signal of the port P3. Further, the crosstalk between the upstream signal light (1480 to 1500 nm) and the video signal transmission signal light (1539 to 1565 nm) to the port P1 can be about 15 dB or more. Therefore, when adding a wavelength for video signal transmission, about 3 dB or more is given to the optical signal as compared with the method using a new splitter for splitting optical power or another WDM filter as shown in FIG. Loss can be reduced. As a result, it is possible to prevent failure due to deterioration of transmission characteristics and to easily provide video services. Further, the number of wavelengths for video signal transmission is not limited to one, and two or more wavelengths are added from the wavelength band (1539 to 1565 nm) by additionally connecting a multiplexing WDM filter to the port P3. It is also possible.

  In the network configuration in FIG. 13, unlike the configuration in FIG. 1, there is no multi-branch optical power splitter having a large insertion loss between the communication station and the optical MC at each user's home. Therefore, it is not necessary to set the input value of the optical power of the added video signal to the optical fiber transmission line 3 to a large value, and an optical attenuator or the like is inserted before the input to the optical fiber coupler 5 for wavelength multiplexing / demultiplexing. In addition, it is possible to appropriately adjust the input value, and it is possible to suppress signal deterioration due to a nonlinear optical effect that is likely to occur when a large amount of optical power is input. For the video signal in the 1550 nm band, an optical power branching coupler may be appropriately inserted between the wavelength multiplexing / demultiplexing optical fiber coupler 5 and the V-OLT 15. Also, by this adjustment, the requirements for the crosstalk performance of the WDM filter (not shown in FIG. 13) in the optical MC on the user's home side are relaxed, and the configuration shown in FIG. 1 is used on the user home side. It is also possible to use a WDM filter having a lower specification.

  As described above, the standardized wavelength shown in FIG. 2 is obtained while securing the advantage that a sufficient transmission band can be secured in the point-to-point communication system by using the network configuration of the present embodiment. It is possible to easily add or change a service to a specific user under a condition conforming to the arrangement.

<Embodiment 5>
FIG. 14 shows a second embodiment of the optical wavelength division multiplexing network and the method of adding the wavelength used according to the present invention. Here, the optical wavelength division multiplexing network using two wavelengths near 1310 nm and 1490 nm. In this case, it is assumed that a wavelength near 1650 nm for testing and monitoring and a wavelength for video signal transmission near 1550 nm are newly added. The communication station 1 already has a transmitter (light source) 26 that uses one wavelength near 1490 nm as the wavelength of the transmitted signal light, and a receiver 27 that uses one wavelength near 1310 nm as the wavelength of the received signal light. It is assumed that an optical MC 17 having a WDM filter composed of a 2 × 2 WDM optical fiber wavelength coupler shown in FIG. 6 for multiplexing and demultiplexing upstream and downstream signal light is mounted.

  In such a case, as described in the second embodiment, one end of the 2 × 2 WDM optical fiber wavelength coupler 33 is connected to one port on the other end of the 2 × 2 WDM optical fiber wavelength coupler 31 shown in FIG. (Connect one) port, and connect one port on one end of the 2 × 2 WDM optical fiber wavelength coupler 32 to one port on the other end of the coupler 33, The optical fiber coupler 6 for wavelength multiplexing / demultiplexing shown in FIG. 9 is mounted in the optical MC 17 on the communication station 1, the receiver 27 is connected to the port P1, the transmitter 26 is connected to the port P2, and the port P3 is connected. The V-OLT 15 for video signal transmission may be connected to the OTDR 19, and the OTDR 19 may be connected to the port P4.

  As already described, in the wavelength multiplexing / demultiplexing optical fiber coupler 6 shown in FIG. 9, a low insertion loss of about 1 dB can be realized in the allocated wavelength range of the video signal of the port P3. Further, the crosstalk between the upstream signal light (1480 to 1500 nm) and the video signal transmission signal light (1539 to 1565 nm) to the port P1 can be about 15 dB or more. Therefore, when adding a video signal transmission wavelength or a test / monitoring wavelength, a new splitter for optical power bifurcation, another WDM filter, or an optical branch module as shown in FIGS. Compared with the method used, the loss given to the optical signal can be reduced by about 3 to 5 dB or more. As a result, it is possible to prevent failure due to deterioration of transmission characteristics and to easily provide video services. Further, the number of wavelengths for video signal transmission is not limited to one, and two or more wavelengths are added from the wavelength band (1539 to 1565 nm) by additionally connecting a multiplexing WDM filter to the port P3. It is also possible.

  In the network configuration in FIG. 14, unlike the configuration in FIG. 1, there is no multi-branch optical power splitter with a large insertion loss between the communication station and the optical MC at each user's home. Therefore, it is not necessary to set the input value of the optical power of the video signal to be added to the optical fiber transmission line 3 to a large value, and an optical attenuator or the like is inserted before the input to the optical fiber coupler 6 for wavelength multiplexing / demultiplexing. In addition, it is possible to appropriately adjust the input value, and it is possible to suppress signal deterioration due to a nonlinear optical effect that is likely to occur when a large amount of optical power is input. For the video signal in the 1550 nm band, an optical power branching coupler may be appropriately inserted between the wavelength multiplexing / demultiplexing optical fiber coupler 6 and the V-OLT 15. Further, by this adjustment, the requirements for the crosstalk performance of the WDM filter (not shown in FIG. 14) in the optical MC at the user's home side are relaxed and used in the user home side in the configuration of FIG. It is also possible to use a WDM filter having a lower specification.

  As described above, the standardized wavelength shown in FIG. 2 is obtained while securing the advantage that a sufficient transmission band can be secured in the point-to-point communication system by using the network configuration of the present embodiment. Test / monitoring for a specific user and addition or change of a service can be easily realized under conditions conforming to the arrangement.

<Embodiment 6>
FIG. 15 shows a third embodiment of the optical wavelength division multiplexing network and the method of adding the wavelength used according to the present invention. Here, an optical wavelength division multiplexing network using two wavelengths near 1310 nm and 1490 nm. , A new wavelength near 1650 nm for testing and monitoring, a wavelength for video signal transmission near 1550 nm, and wavelengths near 1610 nm and 1430 nm for additional services (wavelength 1 and wavelength 2) are added. Assume the case. The communication station 1 already has a transmitter (light source) 26 that uses one wavelength near 1490 nm as the wavelength of the transmitted signal light, and a receiver 27 that uses one wavelength near 1310 nm as the wavelength of the received signal light. It is assumed that an optical MC 17 having a WDM filter composed of a 2 × 2 WDM optical fiber wavelength coupler shown in FIG. 6 for multiplexing and demultiplexing upstream and downstream signal light is mounted.

  In such a case, as described in the third embodiment, one port on the other end side of the 2 × 2 WDM optical fiber wavelength coupler 31 shown in FIG. (Any one) port is connected, one port on the other end side of the coupler 33 is connected to one port (one side) of the 2 × 2 WDM optical fiber wavelength coupler 32, and the 2 × 2 WDM is connected A port on one end side of the 2 × 2 WDM optical fiber wavelength coupler 34 is connected to the other port on the other end side of the optical fiber wavelength coupler 31, and the other end of the 2 × 2 WDM optical fiber wavelength coupler 33 is further connected. 11 is connected to one end of the 2 × 2 WDM optical fiber wavelength coupler 35, and the optical fiber coupler 7 for wavelength multiplexing / demultiplexing shown in FIG. It is mounted in the optical MC 17 on the station 1 side, the receiver 27 is connected to the port P1, the transmitter 26 is connected to the port P2, the V-OLT 15 for video signal transmission is connected to the port P3, and the port P4 is connected. The OTDR 19 is connected, and the transmitters 21 and 22 for additional services may be connected to the ports P5 and P6, respectively.

  As already described, the wavelength multiplexing / demultiplexing optical fiber coupler 7 shown in FIG. 11 can realize a low insertion loss of about 1 dB in the allocated wavelength range of the video signal of the port P3, and is compatible with a new additional service. The same low insertion loss can be realized for ports P5 and P6. Also, signal light for upstream (1480-1500 nm), signal light for video signal transmission (1539-1565 nm), signal light of wavelength 1 for additional service (assuming 1600-1620 nm) and additional service to port P1 Crosstalk with signal light having a wavelength of 2 (assuming 1420 to 1440 m) can be about 15 dB or more. Therefore, when adding a wavelength such as a video signal wavelength or a test / monitoring wavelength, a splitter for splitting optical power, another WDM filter, or an optical branching module as shown in FIGS. Compared with the method used, the loss given to the optical signal can be reduced by about 3 to 5 dB or more. As a result, it is possible to prevent failure due to deterioration of transmission characteristics and to easily provide video services.

  Further, the number of wavelengths for video signal transmission is not limited to one, and two or more wavelengths are added from the wavelength band (1539 to 1565 nm) by additionally connecting a multiplexing WDM filter to the port P3. It is also possible. Further, the wavelengths 1 and 2 for the additional service do not necessarily need to be assigned to a new service, and may be used, for example, for upgrading the transmission rate of the Ethernet signal.

  In the network configuration in FIG. 15, unlike the configuration in FIG. 1, there is no multi-branch optical power splitter having a large insertion loss between the communication station and the optical MC at each user's home. Therefore, it is not necessary to set the input value of the optical power of the video signal to be added or the additional service signal to the optical fiber transmission line 3 to be a large value, and the optical attenuation is performed before the input to the optical fiber coupler 7 for wavelength multiplexing / demultiplexing. It is also possible to adjust the input value appropriately by inserting a measuring device or the like, and it is possible to suppress signal deterioration due to the nonlinear optical effect that is likely to occur at the time of large input of optical power. For the video signal in the 1550 nm band, an optical power branching coupler may be appropriately inserted between the wavelength multiplexing / demultiplexing optical fiber coupler 7 and the V-OLT 15. Also, by this adjustment, the requirements for the crosstalk performance of the WDM filter (not shown in FIG. 15) in the optical MC on the user's home side are relaxed, and the configuration shown in FIG. 1 is used on the user home side. It is also possible to use a WDM filter having a lower specification.

  As described above, the standardized wavelength shown in FIG. 2 is obtained while securing the advantage that a sufficient transmission band can be secured in the point-to-point communication system by using the network configuration of the present embodiment. It is possible to easily realize test / monitoring and addition / change of a service or upgrade of transmission speed to a specific user under conditions conforming to the arrangement.

  By the way, in the fourth, fifth, and sixth embodiments, there is a possibility that a signal having a wavelength other than 1310 nm is reflected and leaks to the port P1. However, the crosstalk of the optical fiber coupler for wavelength multiplexing / demultiplexing of the present invention can be about 15 dB or more, and the return loss of the optical connector connection point generally used in the optical fiber transmission line is about 30 to 40 dB. Further, in the network configuration of the present invention, the optical power of the service signal can be appropriately adjusted as described above, so that the influence of reflected light is not a problem level under normal conditions. However, depending on the type of connector used in the transmission path, a cross-pass performance can be achieved by inserting a band-pass filter or the like that transmits only a wavelength near 1310 nm at the output end of the port P1 (insertion loss is generally about 1 dB). And the influence of leakage of reflected light can be suppressed.

  INDUSTRIAL APPLICABILITY The present invention can be used for designing an economical and low-loss WDM filter and for constructing and designing an optical wavelength division multiplexing communication network in which services can be easily added or changed.

Configuration diagram showing an example of a point-to-multipoint optical wavelength division multiplexing network Explanatory drawing which shows wavelength arrangement (ITU-T G983.3) of signal light in the B-PON system Configuration diagram showing an example of a point-to-point optical wavelength division multiplexing network Configuration diagram showing an example of a point-to-point optical wavelength division multiplexing network with added test and monitoring wavelengths and new service wavelengths Configuration diagram showing another example of a point-to-point optical wavelength division multiplexing network with added test and monitoring wavelengths and new service wavelengths The block diagram which shows the fundamental component of the optical fiber coupler for wavelength multiplexing / demultiplexing of this invention The block diagram which shows 1st Embodiment of the optical fiber coupler for wavelength multiplexing / demultiplexing of this invention The figure which shows the coupling efficiency characteristic of the optical fiber coupler for wavelength multiplexing / demultiplexing of FIG. The block diagram which shows 2nd Embodiment of the optical fiber coupler for wavelength multiplexing / demultiplexing of this invention The figure which shows the coupling efficiency characteristic of the optical fiber coupler for wavelength multiplexing / demultiplexing of FIG. The block diagram which shows 3rd Embodiment of the optical fiber coupler for wavelength multiplexing / demultiplexing of this invention The figure which shows the coupling efficiency characteristic of the optical fiber coupler for wavelength multiplexing / demultiplexing of FIG. The block diagram which shows 1st Embodiment of the optical wavelength division multiplexing network of this invention, and the addition method of its use wavelength The block diagram which shows 2nd Embodiment of the optical wavelength division multiplexing network of this invention, and the addition method of the use wavelength. The block diagram which shows 3rd Embodiment of the optical wavelength division multiplexing network of this invention, and the addition method of the use wavelength.

Explanation of symbols

  1: Communication station, 2, 2-1 to 2-3: User's house, 3, 3-1 to 3-3: Optical fiber transmission line, 4: Optical power splitter, 5, 6, 7: For wavelength multiplexing / demultiplexing Optical fiber coupler, 11: B-PON OLT, 12: B-PON ONU, 13, 14, 23, 25, 28: WDM filter, 15: V-OLT, 16: V-ONU, 17, 17-1 to 17 −3, 18, 18-1 to 18-3: optical MC, 19: OTDR, 20: optical branching module, 21, 22, 26: transmitter (light source), 24: splitter for splitting optical power, 27: reception 29: Test wavelength cut-off filter 31, 32, 33, 34, 35: Optical fiber coupler for wavelength multiplexing / demultiplexing (2 × 2 WDM optical fiber wavelength coupler).

Claims (6)

Wavelength formed by connecting at least two stages of wavelength multiplexing / demultiplexing optical fiber couplers having transmittance characteristics that periodically change on the wavelength axis, one end side having at least one port, and the other end side having two ports An optical fiber coupler for multiplexing / demultiplexing,
At least one of the two ports on the other end side of the first-stage wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band with a 60 nm interval (120 nm cycle) is provided with a 120 nm interval (240 nm cycle) or 240 nm. It is formed by connecting a port on one end side of a second-stage wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band with an interval (480 nm period),
Or in addition to this, at least one of the two ports on the other end side of the second-stage wavelength multiplexing / demultiplexing optical fiber coupler has a three-stage transmission wavelength band having an interval of 240 nm (a period of 480 nm). An optical fiber coupler for wavelength multiplexing / demultiplexing, wherein a port on one end side of the optical wavelength coupler for wavelength multiplexing / demultiplexing is connected. The optical fiber coupler for wavelength multiplexing / demultiplexing according to claim 1,
The center wavelength of the light transmission wavelength band at one of the two ports on the other end side of the first-stage wavelength multiplexing / demultiplexing optical fiber coupler includes near 1310 nm, 1430 nm, 1550 nm, and 1670 nm. When the center wavelength of the light transmission wavelength band at the other port includes around 1370 nm, around 1490 nm, and around 1610 nm,
As the optical fiber coupler for wavelength multiplexing / demultiplexing after the second stage connected to the one port, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1310 nm. , Using at least a wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including a central wavelength of light transmission wavelength band in the other port in the vicinity of 1550 nm,
Alternatively, in addition to this, as the second-stage wavelength multiplexing / demultiplexing optical fiber coupler connected to the other port, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side At least a wavelength multiplexing / demultiplexing optical fiber coupler having transmission wavelength bands of 120 nm intervals (240 nm period) including the vicinity of 1490 nm and the center wavelength of the transmission wavelength band of light at the other port including the vicinity of 1610 nm. An optical fiber coupler for wavelength multiplexing / demultiplexing. An optical fiber transmission line disposed between the communication station and the user's home, at least one transmitter on the communication station side that converts the input electric signal into signal light and transmits it, and the received signal light as an electric signal At least one receiver on the communication station side to convert to at least one transmission signal light from the transmitter on the communication station side and at least one reception signal light to the receiver on the communication station side in the optical fiber transmission Optical wavelength multiplexing / demultiplexing means on the communication station side that multiplexes / demultiplexes for each wavelength with respect to one end of the path, and at least one user home side transmission that converts the input electric signal into signal light and transmits it And at least one receiver on the user's home side for converting the received signal light into an electrical signal, at least one transmission signal light from the transmitter on the user's home side and at least the receiver on the user home side One received signal light In wavelength-division multiplexing network comprising comprising at least an optical wavelength multiplexing and demultiplexing means of the user's home-side to output to demultiplexing for each wavelength with respect to the other end of the optical fiber transmission line,
An optical wavelength division multiplexing communication network using the optical fiber coupler for wavelength multiplexing / demultiplexing according to claim 1 or 2 as the optical wavelength multiplexing / demultiplexing means on the communication station side. An optical fiber transmission line disposed between the communication station and the user's home, at least one transmitter on the communication station side that converts the input electric signal into signal light and transmits it, and the received signal light as an electric signal At least one receiver on the communication station side to convert to at least one transmission signal light from the transmitter on the communication station side and at least one reception signal light to the receiver on the communication station side in the optical fiber transmission Optical wavelength multiplexing / demultiplexing means on the communication station side that multiplexes / demultiplexes for each wavelength with respect to one end of the path, and at least one user home side transmission that converts the input electric signal into signal light and transmits it And at least one receiver on the user's home side for converting the received signal light into an electrical signal, at least one transmission signal light from the transmitter on the user's home side and at least the receiver on the user home side One received signal light An optical wavelength multiplexing communication network comprising at least a user wavelength optical wavelength multiplexing / demultiplexing means for multiplexing / demultiplexing and inputting / outputting the wavelength at the other end of the optical fiber transmission line, the communication station side The optical wavelength multiplexing / demultiplexing means has at least one port on one end side and two ports on the other end side, and has a transmission wavelength band of light in one of the two ports on the other end side. A transmission wavelength band having a center wavelength of 1310 nm, 1430 nm, 1550 nm, and 1670 nm, and a light transmission wavelength band at the other port of 60 nm intervals (120 nm period) including 1370 nm, 1490 nm, and 1610 nm. At least a first wavelength multiplexing / demultiplexing optical fiber coupler including 1 as a wavelength of transmission signal light from one transmitter on the communication station side. With use of one wavelength of 90nm near, the additional method of wavelength used in the optical wavelength division multiplexing communication network comprising using one wavelength of 1310nm near the wavelength of the received signal light to the one receiver of the communication station,
The one end side has at least one port, the other end side has two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1310 nm, A port on one end side of the second wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including a central wavelength of the light transmission wavelength band in the vicinity of 1550 nm. Connect to one port on the other end of the optical fiber coupler for wavelength multiplexing / demultiplexing
The received signal light is output from one of the two ports on the other end side of the second wavelength multiplexing / demultiplexing optical fiber coupler to one receiver on the communication station side, and the other port is output to the other port. A method of adding a wavelength to be used in an optical wavelength division multiplexing communication network, wherein signal light for video signal transmission having at least one wavelength near 1550 nm is input. An optical fiber transmission line disposed between the communication station and the user's home, at least one transmitter on the communication station side that converts the input electric signal into signal light and transmits it, and the received signal light as an electric signal At least one receiver on the communication station side to convert to at least one transmission signal light from the transmitter on the communication station side and at least one reception signal light to the receiver on the communication station side in the optical fiber transmission Optical wavelength multiplexing / demultiplexing means on the communication station side that multiplexes / demultiplexes for each wavelength with respect to one end of the path, and at least one user home side transmission that converts the input electric signal into signal light and transmits it And at least one receiver on the user's home side for converting the received signal light into an electrical signal, at least one transmission signal light from the transmitter on the user's home side and at least the receiver on the user home side One received signal light An optical wavelength multiplexing communication network comprising at least a user wavelength optical wavelength multiplexing / demultiplexing means for multiplexing / demultiplexing and inputting / outputting the wavelength at the other end of the optical fiber transmission line, the communication station side The optical wavelength multiplexing / demultiplexing means has at least one port on one end side and two ports on the other end side, and has a transmission wavelength band of light in one of the two ports on the other end side. A transmission wavelength band having a center wavelength of 1310 nm, 1430 nm, 1550 nm, and 1670 nm, and a light transmission wavelength band at the other port of 60 nm intervals (120 nm period) including 1370 nm, 1490 nm, and 1610 nm. At least a first wavelength multiplexing / demultiplexing optical fiber coupler including 1 as a wavelength of transmission signal light from one transmitter on the communication station side. With use of one wavelength of 90nm near, the additional method of wavelength used in the optical wavelength division multiplexing communication network comprising using one wavelength of 1310nm near the wavelength of the received signal light to the one receiver of the communication station,
One end side has at least one port, the other end side has two ports, and the center wavelength of the light transmission wavelength band in one of the two ports on the other end side is around 1310 nm and around 1550 nm. Including one end of a second wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band with 120 nm intervals (240 nm period) including a wavelength near 1430 nm and a wavelength near 1670 nm. A port connected to one port on the other end side of the first wavelength multiplexing / demultiplexing optical fiber coupler;
The one end side has at least one port, the other end side has two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1310 nm, A port on one end side of a third wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including the vicinity of 1550 nm of the center wavelength of the transmission wavelength band of light in the second port. Connect to one port on the other end of the optical fiber coupler for wavelength multiplexing / demultiplexing
Signal light for testing and monitoring an optical fiber transmission line having one wavelength near 1650 nm is input through the other of the two ports on the other end side of the second wavelength multiplexing / demultiplexing optical fiber coupler. Output the received signal light from one of the two ports on the other end side of the third wavelength multiplexing / demultiplexing optical fiber coupler to one receiver on the communication station side, and A method of adding a wavelength to be used in an optical wavelength division multiplexing network, wherein signal light for video signal transmission having at least one wavelength in the vicinity of 1550 nm is input to the port. The method of adding a wavelength used in the optical wavelength division multiplexing network according to claim 5,
In addition to the above
The one end side has at least one port, the other end side has two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1490 nm, A port on one end side of a fourth wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 120 nm intervals (240 nm period) including the vicinity of 1370 nm and the vicinity of 1610 nm as the center wavelength of the transmission wavelength band of light in Connected to the other port on the other end of the first wavelength multiplexing / demultiplexing optical fiber coupler;
The one end side has at least one port, the other end side has two ports, the center wavelength of the light transmission wavelength band in one of the two ports on the other end side includes the vicinity of 1430 nm, A port on one end side of a fifth wavelength multiplexing / demultiplexing optical fiber coupler having a transmission wavelength band of 240 nm intervals (480 nm period) including a central wavelength of light transmission wavelength band in the vicinity of 1670 nm. Connected to the other port on the other end of the wavelength multiplexing / demultiplexing optical fiber coupler,
The received signal light is output from one of the two ports on the other end side of the third wavelength multiplexing / demultiplexing optical fiber coupler to the one receiver on the communication station side, and the other port is output to the other port. A signal light for video signal transmission having at least one wavelength near 1550 nm is input, and the communication station is connected to one of two ports on the other end side of the fourth wavelength multiplexing / demultiplexing optical fiber coupler. The transmission signal light from one transmitter on the side is input, and from one wavelength near 1650 nm through the other of the two ports on the other end of the fifth wavelength multiplexing / demultiplexing optical fiber coupler Input and output signal light for testing and monitoring optical fiber transmission lines
Furthermore, transmission signal light from another transmitter on the communication station side having one wavelength near 1610 nm is sent to the other of the two ports on the other end side of the fourth wavelength multiplexing / demultiplexing optical fiber coupler. Input or transmission from another transmitter on the communication station side having one wavelength near 1430 nm to one of the two ports on the other end side of the fifth wavelength multiplexing / demultiplexing optical fiber coupler Input signal light,
Alternatively, transmission signal light from another transmitter on the communication station side having one wavelength near 1610 nm is transmitted to the other of the two ports on the other end side of the fourth wavelength multiplexing / demultiplexing optical fiber coupler. Input from one of the two ports on the other end side of the fifth wavelength multiplexing / demultiplexing optical fiber coupler and transmission from another transmitter on the communication station side having one wavelength near 1430 nm A method of adding a wavelength to be used in an optical wavelength division multiplexing network, characterized by inputting signal light.

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