KR100584382B1 - Passive optical network using wavelength interleaver - Google Patents

Abstract

A passive optical subscriber network communicating over a series of channels according to the present invention is connected to a trunk fiber and has a first wavelength shift for transmitting odd channels of the series of channels and receiving even channels of the series of channels. A central base station including a filter; A local base station connected to the central base station through the trunk fiber, and configured to transmit input even channels to the central base station and to distribute the input odd channels; And a subscriber device coupled to the local base station via a plurality of distributed optical fibers, for transmitting even channels to the local base station, and receiving the odd channels from the local base station.

Passive optical subscriber network, wavelength alternating filter, broadband light source, wavelength division multiplexer

Description

Passive optical subscriber network using wavelength shift filter {PASSIVE OPTICAL NETWORK USING WAVELENGTH INTERLEAVER}             

1 is a view showing the configuration of a conventional wavelength division multiplex passive optical subscriber network;

FIG. 2 is a diagram illustrating a downlink wavelength band and an uplink wavelength band used in the passive optical subscriber network shown in FIG. 1;

3 is a diagram showing the configuration of a passive optical subscriber network according to a first preferred embodiment of the present invention;

4 is a view for explaining input and output characteristics of the first wavelength shift filter shown in FIG. 1;

5 is a diagram showing the configuration of a passive optical subscriber network according to a second preferred embodiment of the present invention.

TECHNICAL FIELD The present invention relates to a passive optical subscriber network, and more particularly, to a passive optical subscriber network of a wavelength division multiplexing scheme using uplink and downlink bands superimposed on each other.

Wavelength-division-multiplexed (WDM) passive optical networks (PONs) provide ultra-high speed broadband communications services using unique wavelengths assigned to each subscriber. Therefore, the confidentiality of the communication is assured, and it is easy to accommodate the expansion of the separate communication service or communication capacity required by each subscriber, and the number of subscribers can be easily expanded by adding the unique wavelength to be given to the new subscriber. . In spite of these advantages, subscribers are required in the central office (CO) and in each optical network unit (ONU) by the need of additional wavelength stabilization circuits to stabilize the wavelength of the light source and the wavelength of the particular oscillation wavelength. The wavelength division multiplex passive optical subscriber network has not been put to practical use because of the high economic burden on the consumer. Therefore, economical wavelength division multiplexing light source development is essential for implementing a wavelength division multiplexing passive optical subscriber network. In particular, when using a bi-directional single transceiver module for price competitiveness, the wavelength band input and output should be considered.

A wavelength division multiplexing passive optical subscriber network using a distributed feedback laser (DFB laser), a light emitting diode (LED), etc. has been proposed as a wavelength division multiplexing light source.

1 is a view showing the configuration of a passive optical subscriber network of the wavelength division multiplexing method according to the prior art. FIG. 2 is a diagram illustrating a downlink wavelength band 220 and an uplink wavelength band 230 used in the passive optical subscriber network 100 shown in FIG. 1. The passive optical subscriber network 100 includes a central base station 110, a remote node RN 160 connected to the central base station 110 through a main optical fiber MF 150, and a plurality of And a subscriber station (190) connected to the local base station (160) via distribution optical fibers (DF) 180-1 to 180-n. The passive optical subscriber network 100 communicates using a series of first to nth channels as shown in FIG. 2, and the first to mth (? N / 2) channels are the downlink wavelength band 220. And the (m + 1) to n-th channels form an upward wavelength band 230.

The central base station 110 includes first to mth down transmitters (DOWN TX, 120-1 to 120-m), and first to mth upward receivers (UP RX, 130-1). 130-m) and a first wavelength division multiplexer (WDM) 140.

The first to mth downlink transmitters 120-1 to 120-m are connected to the first wavelength division multiplexer 140 and output first to mth channels. The m th downlink transmitter 120-m outputs an m th channel.

The first to mth upstream receivers 130-1 to 130-m are connected to the first wavelength division multiplexer 140 and detect (m + 1) to nth channels as electrical signals. . The m-th upstream receiver 130-m detects the nth channel as an electrical signal.

The first wavelength division multiplexer 140 is connected to a multiplexing port (MP) connected to the trunk fiber 150 and one-to-one connected to the first to mth downlink transmitters 120-1 to 120-m. (M + 1) to nth demultiplexing ports connected to first to mth demultiplexing ports DP and one-to-one connected to the first to mth receivers 130-1 to 130-m Have them. The first wavelength division multiplexer 140 multiplexes the first to mth channels input to the first to nth demultiplexing ports and outputs them to the multiplexing port, and inputs (m + 1) to the multiplexing port. The n th channels are demultiplexed and output to the (m + 1) th to n th ports.

The local base station 160 is connected to the central base station 110 through the trunk optical fiber 150, and the subscriber station 190 through the first to nth distributed optical fibers 180-1 to 180-n. Connected with The local base station 160 includes a second wavelength division multiplexer 170.

The second wavelength division multiplexer 170 may include a multiplexing port connected to the trunk optical fiber 150 and first to nth stations connected one-to-one with the first to n-th distribution optical fibers 180-1 to 180-n. It has multiplexed ports. The n th demultiplexing port of the second wavelength division multiplexer 170 is connected to the n th distribution optical fiber 180-n. The second wavelength division multiplexer 170 demultiplexes the first to m th channels input to the multiplexing port and outputs the first to m th demultiplexing ports, and outputs the (m + 1) to n th demultiplexers. The m-th to n-th channels input to the ports are multiplexed and output to the multiplexed port. The m th channel is output to an m th demultiplexing port of the second wavelength division multiplexer 170.

The subscriber device 190 is connected to the local base station 160 through the first to nth distributed optical fibers 180-1 to 180-n, and the first to mth downlink receivers DOWN RX, 200. -1 to 200-m) and first to mth uplink transmitters (UP TX, 210-1 to 210-m).

The first to m th down receivers 200-1 to 200-m are connected one-to-one with the first to m th split optical fibers 180-1 to 180-m, and the m th down receiver 200-to m) is connected to the m-th distribution optical fiber 180-m. The first to m th down receivers 200-1 to 200-m detect the input first to m th channels as electrical signals, and the m th down receiver 200-m is input to the m th input terminal. Detect the channel as an electrical signal.

The first to mth uplink transmitters 210-1 to 210-m are connected one-to-one with the (m + 1) to n-th distribution optical fibers 180- (m + 1) to 180-n. The m th uplink transmitter 210-m is connected to the n th distribution fiber 180-n. The first to mth upstream transmitters 210-1 to 210-m output the (m + 1) to nth channels, and the mth uplink transmitter 210-m outputs an nth channel. .

However, in the conventional passive optical subscriber network as described above, in order to increase the number of uplink and downlink channels as subscribers increase, the channel spacing in a given wavelength band should be reduced or the assignable wavelength bandwidth should be increased. In order to reduce the channel spacing, the processing wavelengths of the first and second wavelength division multiplexers have to be adjusted more precisely, which leads to an increase in device price. In addition, when the wavelength band is widened, characteristics such as loss and dispersion of components or optical fibers are different depending on the wavelength of the channel, thereby causing a difference in transmission quality for each channel. In order to solve such a problem, an additional component or circuit supplement that can precisely adjust transmission characteristics is required, but there is a problem in that it is not economical in this case.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to increase the number of channels as compared to the prior art within a limited transmission wavelength band, and to maintain a wide interval between upstream or downstream channels. To provide an economical bidirectional wavelength division multiplexing passive optical subscriber network capable of adopting a low-cost device.

In order to achieve the above object, a passive optical subscriber network communicating with a series of channels according to the present invention is connected to an edge optical fiber, transmits odd channels of the series of channels and even channels of the series of channels. A central base station comprising a first wavelength shift filter for receiving the signals; A local base station connected to the central base station through the trunk fiber, and configured to transmit input even channels to the central base station and to distribute the input odd channels; And a subscriber device coupled to the local base station via a plurality of distributed optical fibers, for transmitting even channels to the local base station, and receiving the odd channels from the local base station.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

3 is a view showing the configuration of a passive optical subscriber network according to a first embodiment of the present invention, Figure 4 is a view for explaining the input and output characteristics of the first wavelength shift filter shown in FIG. The passive optical subscriber network 300 includes a central base station 310, a local base station 380 connected to the central base station 310 through an trunk fiber 370, and a plurality of distributed optical fibers 420-1 to 420-. n) a subscriber station 430 connected to the local base station 380 through n). The passive optical subscriber network 300 communicates using a series of first through n-th channels as shown in FIG. 4, and includes a downlink wavelength band composed of odd channels among the series of first through n-th channels. 460 and the upward wavelength band 470 composed of even channels of the series of first to nth channels overlap each other.

The central base station 310 and the first to m (≤ n / 2) downlink transmitters (320-1 ~ 320-m), the first to m-th upstream receivers (340-1 ~ 340-m) and And first and second wavelength division multiplexers 330 and 350 and a first wavelength interleaver IL 360.

The first to mth downlink transmitters 320-1 to 320-m are connected to the first wavelength division multiplexer 330 and output odd channels. The mth downlink transmitter 320-m outputs the (n−1) th channel.

The first wavelength division multiplexer 330 may include a multiplexing port connected to the first wavelength shift filter 360, and first to one first connections to the first to mth down transmitters 320-1 to 320-m. Mth demultiplexing ports. The m-th demultiplexing port of the first wavelength division multiplexer 330 is connected to the m-th downlink transmitter 320-m. The first wavelength division multiplexer 330 multiplexes odd-numbered channels input to the first to m-th demultiplexing ports and outputs the multiplexed ports. The first and second wavelength division multiplexers 330 and 350 may each include an arrayed waveguide grating (AWG).

The first to mth upstream receivers 340-1 to 340-m are connected to the second wavelength division multiplexer 350 and detect even channels as electrical signals. The mth upstream receiver 340-m detects the nth channel as an electrical signal.

The second wavelength division multiplexer 350 may include a multiplexing port connected to the first wavelength shift filter 360, and first to one first connections to the first to mth upstream receivers 340-1 to 340-m. Mth demultiplexing ports. The m-th demultiplexing port of the second wavelength division multiplexer 350 is connected to the m-th uplink transmitter 340-m. The second wavelength division multiplexer 350 demultiplexes even channels input to the multiplexing port and outputs the first to m th demultiplexing ports.

3 and 4, the first wavelength shift filter 360 has first to third ports, and the first port is connected to the multiplexing port of the first wavelength division multiplexer 330. Two ports are connected to the trunk fiber 370, and a third port is connected to a multiplexing port of the second wavelength division multiplexer 350. The first wavelength shift filter 360 outputs the odd channels inputted to the first port to a second port, and outputs even channels inputted to the second port to a third port.

The local base station 380 is connected to the central base station 310 via the trunk fiber 370, and the subscriber station 430 through the first to nth distributed optical fibers 420-1 to 420-n. Connected with The local base station 380 includes a second wavelength alternate filter 390 and third and fourth wavelength division multiplexers 400 and 410.

The second wavelength shift filter 390 has first to third ports, and the first port is connected to the multiplexing port of the fourth wavelength division multiplexer 410, and the second port is the trunk fiber 370. The third port is connected to the multiplexing port of the third wavelength division multiplexer 400. The second wavelength shift filter 390 outputs the even channels input to the first port to a second port and outputs the odd channels input to the second port to a third port.

The third wavelength division multiplexer 400 is one-to-one with a multiplexing port connected to a third port of the second wavelength alternating filter 390 and the first to mth distribution optical fibers 420-1 to 420-m. Having first to mth demultiplexing ports connected. The m-th demultiplexing port of the third wavelength division multiplexer 400 is connected to the m-th distribution optical fiber 420-m. The third wavelength division multiplexer 400 demultiplexes odd channels input to the multiplexing port and outputs the first to n th demultiplexing ports. The (n-1) th channel is output to the mth port of the third wavelength division multiplexer. The third and fourth wavelength division multiplexers 400 and 410 may each include a waveguide diffraction grating.

The fourth wavelength division multiplexer 410 includes a multiplexing port connected to a first port of the second wavelength shift filter 390 and the (m + 1) to n th distribution optical fibers 420-(m + 1). ) To 420-n) have first to mth demultiplexing ports connected one-to-one. The m th demultiplexing port of the fourth wavelength division multiplexer 410 is connected to the n th distribution optical fiber 420-n. The fourth wavelength division multiplexer 410 multiplexes even channels input to the first to mth demultiplexing ports and outputs the multiplexed ports. The nth channel is input to an mth port of the fourth wavelength division multiplexer 410.

The subscriber device 430 is connected to the local base station 380 through the first to nth distributed optical fibers 420-1 to 420-n, and the first to mth downlink receivers 440-1 to 440-m) and first to m th upward transmitters 450-1 to 450-m.

The first to m th down receivers 440-1 to 440-m are connected one-to-one with the first to m th split optical fibers 420-1 to 420-m, and the m th down receiver 440-m. m) is connected to the m-th distribution optical fiber 420-m. The first to m th down receivers 440-1 to 440-m detect the input odd channels as electrical signals, and the m th down receiver 440-m is input to the n th input terminal. Detect the channel as an electrical signal.

The first to mth uplink transmitters 450-1 to 450-m are connected one-to-one with the (m + 1) to n-th distribution optical fibers 420- (m + 1) to 420-n. The m-th uplink transmitter 450-1 is connected to the n-th distribution optical fiber 420-n. The first to mth upstream transmitters 450-1 to 450-m output even channels, and the mth uplink transmitter 450-1 outputs an nth channel.

5 is a diagram showing the configuration of a passive optical subscriber network according to a second preferred embodiment of the present invention. The passive optical subscriber network 500 has a configuration in which a broadband light source (BLS, 570) and an optical coupler (OC, 580) are further added to the configuration shown in FIG. Hereinafter, the overlapping description will be omitted and only the broadband light source 570 and the optocoupler 580 will be described in detail.

The broadband light source 570 is connected to the optocoupler 580 and outputs upward and downward broadband light.

The optocoupler 580 has first to fourth ports, the first port being connected to a second port of the first wavelength alternating filter 560, and the second and third ports being connected to the broadband light source 570. The fourth port is connected to the trunk fiber 590. The optocoupler 580 outputs odd channels input to the first port to the fourth port, outputs downlink broadband light input to the second port to the fourth port, and outputs uplink broadband light input to the third port. It outputs to the first port and outputs even channels inputted to the fourth port to the first port.

The upward broadband light output to the first port of the optocoupler 580 is input to the second port of the first wavelength shift filter 560 and output to the first port. The first wavelength division multiplexer 530 spectrally divides the uplink broadband light inputted to the multiplexing port and outputs the first to nth demultiplexing ports. The spectral divided lights are injected into the first to m th down transmitters 520-1 to 520-m, and the first to m th down transmitters 520-1 to 520-m are respectively inputted injected light The wavelength is immersed in and outputs a channel having the same wavelength as that of the injected light. The first to m th down transmitters 520-1 to 520-m output odd channels by the injection lights, and the m th down transmitter 520-m receives the (n−1) th channel. Output The first to mth down transmitters 520-1 to 520-m may each be a mode-locked Fabry-Perot laser with incoherent light or a wavelength-seeded reflective semiconductor optical. a wavelength injection light source, such as an amplifier).

The downlink broadband light output to the fourth port of the optocoupler 580 is input to the second port of the second wavelength shift filter 610 of the local base station 600 through the trunk fiber 590. The second wavelength shift filter 610 outputs the downlink broadband light inputted to the second port to the first port. The fourth wavelength division multiplexer 630 spectrally divides the downlink wideband light input to the multiplexing port and outputs the first and m th demultiplexing ports. The spectral divided lights pass through the (n + 1) to n th distribution optical fibers 640-(m + 1) to 640-n, and the first to m th upward transmitters 670-1 of the subscriber device 650. To 670-m). The first to mth upstream transmitters 670-1 to 670-m are respectively locked in wavelength by the input injection light and output a channel having the same wavelength as that of the injection light. The first to mth upstream transmitters 670-1 to 670-m output even channels by the injection lights, and the mth uplink transmitter 670-m outputs an nth channel. The first to mth upward transmitters 670-1 to 670-m each include a wavelength injection light source such as a Fabry-Perot laser or a reflective semiconductor optical amplifier.

As described above, the passive optical subscriber network using the wavelength alternating filter according to the present invention can accommodate more subscribers with a limited signal wavelength band than the conventional one by overlapping the upstream and downstream wavelength bands, The advantage of maintaining a wide spacing is that it is possible to construct an economical network that can adopt general purpose devices.

Claims (9)

In a passive optical subscriber network communicating over a series of channels, A central base station connected to an edge fiber and including a first wavelength shift filter for transmitting odd channels of the series of channels and receiving even channels of the series of channels; A local base station connected to the central base station through the trunk fiber, and configured to transmit input even channels to the central base station and to distribute the input odd channels; And a subscriber station coupled to the local base station via a plurality of distributed optical fibers, for transmitting even channels to the local base station, and receiving the odd channels from the local base station. The method of claim 1, wherein the central base station, A plurality of downlink transmitters for outputting odd channels; A first wavelength division multiplexer for multiplexing the odd channels to provide the first wavelength shift filter; A second wavelength division multiplexer for demultiplexing even channels input from the first wavelength shift filter; And a plurality of upstream receivers for detecting the even channels as electrical signals. The method of claim 2, And said downlink transmitters each comprise a wavelength injection light source. The method of claim 2, And said first and second wavelength division multiplexers each comprise a waveguide diffraction grating. The method of claim 1, wherein the local base station, A second wavelength shift filter for transmitting odd channels input from the central base station to the subscriber station and transmitting the input even channels to the central base station; A third wavelength division multiplexer for demultiplexing the odd channels for distribution to the distribution optical fibers; And a fourth wavelength division multiplexer for multiplexing even channels input from the subscriber device and providing the second wavelength shift filter. delete The method of claim 5, And said third and fourth wavelength division multiplexers each comprise a waveguide diffraction grating. The method of claim 2, wherein the subscriber device, A plurality of uplink transmitters for transmitting even channels to the local base station; And a plurality of downlink receivers for detecting odd channels received from said local base station as electrical signals. The method of claim 8, wherein the central base station, A broadband light source for outputting upward and downward broadband lights; And an optical coupler for providing the uplink wideband light to downlink transmitters of the central base station and for providing the downlink wideband light to the uplink transmitters.

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