JPH09247179A - Optical receiver and optical network using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the receiver increasing a throughput between optical transmitter and receiver by providing plural optical interruption means in which one means is turned on and the other is turned off, a wavelength router and plural optical reception means. SOLUTION: While an optical modulator 120 is active, when any of other optical modulators 122, 123, 124 is activated, 4-parallel optical transmission from optical transmitters 20t, 30t, 40t is respectively realized. Similar 4-parallel optical transmission is realized by operating each optical modulator array in other optical receivers. Thus, the 4×4 nonblocking optical switching as to 4-parallel optical transmission channels is realized by four optical modulators for one optical receiver. Four parallel optical signals from a multi-wavelength semiconductor laser array 110 of the optical transmitter 10t are received entirely by a light receiver array 140 of the optical receiver 10r to realize the 4-parallel optical transmission from the optical transmitter 10t to the optical receiver 10r.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical network capable of dynamically setting a large-capacity information transmission channel between a plurality of optical transceivers, and an optical receiver used in the optical network.

[0002]

2. Description of the Related Art As the throughput of a network increases, a modular architecture, in which the capacity can be increased step by step and a failure part can be easily separated, is attracting attention. For example, in order to construct an ATM switch having a throughput of 100 Gb / s or more, an architecture has been proposed in which a plurality of input / output buffer modules having a throughput of 10 Gb / s are connected via a star-shaped optical network.
In the following (E. Munter, et al., "A High-Capacity A
TM Switch Based on Advanced Electronic and Optica
l Technologies ", IEEE Communications Magazine, No
v. 1995, pp. 64-71), the architecture of the ATM switch is shown in FIG. 10, and the conventional optical receiver and optical network used therein are described with reference to FIG.

In FIG. 10, an input / output buffer 61 and an optical transmitter / receiver 62 having a transmission speed of 10 Gb / s, which can be added in module units, are connected via a non-blocking optical switch 63. That is, the non-blocking optical switch 63 constitutes an optical network in which a plurality of optical transceivers 62 are connected in a star shape. At this time, a plurality of 10 Gb / s information transmission channels can be simultaneously set between different input / output buffers 61. For example, while information is being transferred from the first input buffer to the second output buffer at 10 Gb / s, information can be transferred from the second input buffer to the third output buffer at 10 Gb / s.

The network controller 64 dynamically changes the setting of the non-blocking optical switch 63 in consideration of the accumulation state of ATM cells in the input / output buffer 61 of each module, and the cell burst from each input buffer (to the same output buffer). A collection of multiple cells). When a 16 × 16 non-blocking optical switch is used in such a configuration, the throughput is 10 Gb / s.
A large-capacity ATM switch that can be expanded in units and has a throughput of up to 160 Gb / s can be realized.

In the configuration of the optical receiver and the optical network shown in FIG. 11, the case of a 4 × 4 optical network is shown for simplicity. In the figure, 1t, 2t, 3t, 4t
Are semiconductor lasers (L
D) An optical transmitter including 11. 1r, 2r, 3r, 4
r is the optical modulator array 120, the optical combiner 13,
It is an optical receiver including a 10 Gb / s light receiver 14. here,
The optical modulator array 120 is composed of four optical modulators 121 to 124 corresponding to each optical transmitter.

[0006] A star-shaped optical wiring is provided between each optical transmitter and each optical receiver. That is, the output of the semiconductor laser 11 of the optical transmitter 1t is sent to the splitter 1 via the optical fiber.
Optical receivers 1r, 2r, 3
They are input to the r and 4r optical modulators 121, respectively. The same applies to the outputs of the semiconductor lasers 11 of the optical transmitters 2t, 3t, and 4t, and the optical modulators 122 to 124 corresponding to the optical receivers 1r, 2r, 3r, and 4r pass through the splitters 200, 300, and 400, respectively. Is entered.

In the conventional optical network shown here,
4 × 4 non-blocking optical switching is realized in a distributed manner by operating the optical modulator array 120 of each optical receiver. In each optical receiver, the optical modulator array 12
Of the four optical modulators 121 to 124 forming 0, only one of them is in a state of transmitting light (on state),
The other three units may be in a state of blocking light (off state). For example, in the optical receiver 1r, the optical modulator 121 is set to O
In the N state, the signal light from the semiconductor laser 11 of the optical transmitter 1t is received by the light receiver 14 via the optical combiner 13. Similarly, in the optical receiver 1r, the optical modulators 122, 1
When either one of 23 and 124 is turned on, it is possible to receive the signal light from the semiconductor laser 11 of each of the optical transmitters 2t, 3t and 4t.

[0008]

In the conventional optical receiver and optical network shown in FIG. 11, the capacity is increased by increasing the information transmission speed between optical transmitters and receivers or by increasing the number of optical transmitters and receivers. Was difficult for the following two reasons. The first reason is that there is a large loss in the light propagation path from the semiconductor laser to the light receiver. In the configuration shown in FIG. 11, for example, the semiconductor laser 1 of the optical transmitter 1t
In the path from 1 to the light receiver 14 of the optical receiver 1r, a distribution loss of 6 dB is generated in the splitter 100, and a 6 dB is generated in the optical combiner 13.
There is a dB loss. When an N × N optical network is configured according to this optical network configuration method, a distribution loss of 10 · log N [dB] occurs at the splitter and 10 · lo at the optical combiner.
A loss of g N [dB] occurs. Therefore, in a 16 × 16 optical network, for example, a loss of at least 12 dB occurs in each of the splitter and the optical receiver. further,
If a high-speed semiconductor light intensity modulator is used, a loss of 5 dB or more cannot be avoided under the present circumstances. Therefore, in consideration of the connection loss and the distribution loss variation, it is necessary to expect a loss of at least 30 dB or more in the optical propagation path from the semiconductor laser to the light receiver.

On the other hand, the optical receiving sensitivity sharply deteriorates when the bit rate is increased, but since the output optical power of the semiconductor laser is limited, the optical propagation loss allowed in a 10 Gb / s optical transmission system is at most 30 dB. However, it was difficult to achieve higher speeds. The problem of large loss makes it difficult to increase the capacity of the entire optical network. That is, it is difficult to design a large number of optical transceivers that can be accommodated because the loss increases as N increases.

The second reason is that it is difficult to increase the speed itself exceeding 10 Gb / s in photoelectric conversion means such as a semiconductor laser and a photodetector and an electronic circuit connected thereto. This is because realization of a digital electronic circuit exceeding 10 Gb / s involves many difficulties due to the limits of fine processing technology and heat radiation technology. By the way, the following two methods can be considered as means for avoiding the above-mentioned first reason.

The first workaround is to provide a 4 × 1 optical switch in place of the optical modulator array 120 and the optical combiner 13 in FIG. 11 to avoid a 6 dB merge loss in the optical combiner 13. However, this 4x1 optical switch is
Unlike a simple optical interrupting means that can be turned off, it is difficult to realize its function with a single element. In addition, a relatively simple 2 × 1 optical switch is connected in a tree form in multiple stages to form an N × 1 optical switch.
Although an optical switch can be constructed, the accumulation of loss is remarkable. Especially, 1 μs is required to change the light propagation path frequently.
When the following switching speed is required, a semiconductor optical device is suitable as an optical switch, but it is difficult to realize a low loss N × 1 optical switch with this semiconductor optical device. Further, there is a problem that the crosstalk is large in general in the N × 1 optical switch.

The second workaround is the optical modulators 121-124.
Instead of avoiding the loss in the optical modulator, a semiconductor optical amplifier is used as the optical interrupting means instead of the above, and the loss in the optical propagation path is compensated by the optical amplification effect. However, there is intersymbol interference called pattern effect in the semiconductor optical amplifier, and it is difficult to handle signal light of several Gb / s or more. In addition, since spontaneous emission light (ASE) is added to the signal light in the optical amplification process, there is a problem that the signal-to-noise ratio deteriorates. Further, when the noise of the electric circuit arranged in the subsequent stage of the photodetector is large, even if the optical amplification is performed, the optical combiner causes a loss, which deteriorates the receiving sensitivity.

Since the present invention cannot be essentially solved by the above-mentioned workarounds, the new configuration causes less loss in the optical propagation path, and facilitates transmission of information between optical transmitters / receivers and throughput of the entire network. An object of the present invention is to provide an optical receiver capable of increasing the capacity and an optical network using the optical receiver.

[0014]

An optical receiver according to claim 1 receives a plurality of wavelength division multiplexed optical signals and turns them on / off.
It has a plurality of optical connecting / disconnecting means to be turned off and a plurality of input ports connected to the plurality of optical connecting / disconnecting means. The configuration is provided with a determined wavelength router and a plurality of optical receiving means connected to a plurality of output ports of the wavelength router, and one optical interrupting means is turned on and the other optical interrupting means is turned off.

The optical receiver according to claim 2 further comprises parallel signal processing means connected to the plurality of optical receiving means.
The optical network according to claim 3, wherein a plurality of optical transmitters each having an optical transmitting unit that outputs a plurality of optical signals having different wavelengths, and a plurality of optical signals output from the optical transmitter are input to perform wavelength multiplexing. Then, a plurality of optical distribution means corresponding to each optical transmitter for distributing the wavelength-division-multiplexed optical signal and a wavelength-multiplexed optical signal output from each of the plurality of optical distribution means are input. And the optical receiver described.
That is, the wavelength division multiplexed optical signals from different optical transmitters are respectively input to the plurality of optical interrupters of the optical receiver.

As described above, the first feature of the present invention resides in that a plurality of optical signals having different wavelengths are transmitted and received in parallel between the optical transmitter and the optical receiver. As a result, information can be developed in parallel and transmitted, and the information transmission rate per optical signal wave can be suppressed. The second feature of the present invention is that in the optical receiver,
A plurality of optical interrupting means corresponding to each optical transmitter and a plurality of optical receiving means corresponding to each wavelength are connected via a wavelength router.

A plurality of optical signals output from each optical transmitting means of the optical transmitter are wavelength-multiplexed and input to the corresponding optical interrupting means of each optical receiver, whereby the optical signals are output from one optical transmitter. It is possible to collectively turn on / off a plurality of optical signals. Then, by turning on one of the plurality of optical connecting / disconnecting means of each optical receiver, only the wavelength-multiplexed optical signal from the specific optical transmitter is selected, and further the plurality of optical signals are demultiplexed by the wavelength router. Guided to receiving means. Here, by using the wavelength router instead of the optical combiner,
The merge loss can be avoided as in the case of using the N × 1 optical switch.

As described above, by combining the parallel optical transmission technology and the optical wavelength multiplexing technology, it is possible to suppress the transmission rate per light wave to be low and reduce the theoretical loss in the optical propagation path. This makes it possible to increase the capacity of information transfer between optical transceivers and the throughput of the entire optical network.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of an optical network and an optical receiver according to the present invention. Here, FIG.
Similar to the conventional example shown in FIG. 1, the structure of a 4 × 4 non-blocking optical switch is shown for simplicity.

In the figure, 10t, 20t, 30t, 4
Reference numeral 0t denotes an optical transmitter, each of which includes a multi-wavelength semiconductor laser array 110 as an optical transmitting means. The multi-wavelength semiconductor laser array 110 has different wavelengths λ1, λ2, λ.
Semiconductor lasers (LD) 111 to 11 that oscillate at 3 and λ4
4 are directly modulated with different data.

Reference numerals 10r, 20r, 30r and 40r denote optical receivers, which are an optical modulator array 120 as an optical interrupter and an arrayed waveguide optical multiplexer / demultiplexer 1 as a wavelength router, respectively.
30 and a light receiver array 140 as a light receiving means.
The optical modulator array 120 is composed of four optical modulators 121 to 124 corresponding to each optical transmitter. The optical receiver array 140 is composed of four optical receivers 141 to 144 corresponding to the respective output ports of the arrayed waveguide optical multiplexer / demultiplexer 130.

FIG. 2 shows the configuration of the arrayed waveguide optical multiplexer / demultiplexer 130. The arrayed waveguide optical multiplexer / demultiplexer 130 has four input ports I corresponding to the four optical modulators 121 to 124.
1 to I4, an input waveguide array 131, an input side slab waveguide 132, a waveguide array 133 arranged with a predetermined waveguide length difference, an output side slab waveguide 134, and four light receivers 1
The output waveguide array 135 having four output ports J1 to J4 corresponding to 41 to 144 is connected in cascade.

FIG. 3 shows wavelength routing characteristics between the input and output ports of the arrayed waveguide optical multiplexer / demultiplexer 130. For example,
Four wavelength-multiplexed optical signals with wavelengths λ1 to λ4 are input ports I
When input to 1, the wavelengths λ1, λ2, λ3, λ4
Optical signal is demultiplexed and output ports J1, J2, J3, J
4 are output respectively. The demultiplexing loss at this time is 3 dB or less in principle. (Reference: H. Takahashi, et.
al., "Transmission Characteristics of arrayed-wave
guide N × N wavelength multiplexer ", IEEE J. Light
wave Technol., vol.13, no.3, pp.447-455, 1995).

In FIG. 1, star-shaped optical wiring is provided between each optical transmitter and each optical receiver. That is, the output of the multi-wavelength semiconductor laser array 110 of the optical transmitter 10t is
It is input to a 4 × 4 star coupler 101 via an optical fiber, multiplexed, then divided into 4 as a wavelength division multiplexed optical signal, and input to an optical modulator 121 of each of the optical receivers 10r, 20r, 30r, 40r. . Optical transmitter 20t, 30
The same applies to the outputs of the multi-wavelength semiconductor laser array 110 of t and 40t.
1, 401 via the optical receivers 10r, 20r, 30r,
It is input to the corresponding optical modulators 122 to 124 of 40r.

In the optical network of this embodiment, 4 × 4
Non-blocking optical switching is distributedly implemented by operating the optical modulator array 120 of each optical receiver. In each of the optical receivers, only one of the four optical modulators 121 to 124 forming the optical modulator array 120 is in a state of transmitting light (ON state), and the other three.
The table may be in a state of blocking light (off state).

Hereinafter, the optical modulator 1 in the optical receiver 10r
A case where 21 is turned on will be described. At this time, the wavelengths λ1 to 1 output from the multi-wavelength semiconductor laser array 110 of the optical transmitter 10t are input to the input port I1 of the arrayed waveguide optical multiplexer / demultiplexer 130 connected to the optical modulator 121.
The optical signal of λ4 is input as a wavelength division multiplexed optical signal. The arrayed waveguide optical multiplexer / demultiplexer 130 routes the optical signals of wavelengths λ1, λ2, λ3, λ4 to the output ports J1, J2, J3, J4 according to the wavelength routing characteristics shown in FIG. It leads to 143,144. As a result, four parallel optical signals from the multi-wavelength semiconductor laser array 110 of the optical transmitter 10t are converted into the optical receiver 10r.
All of the light is received by the photoreceiver array 140, and four parallel optical transmissions from the optical transmitter 10t to the optical receiver 10r are realized.

Similarly, in the optical modulator array 120 of the optical receiver 10r, other optical modulators 122, 123, 124 are provided.
If any one of them is turned on, the optical transmitter 20
4 parallel optical transmission from t, 30t, 40t is realized.
In addition, similar four parallel optical transmission is realized by operating the respective optical modulator arrays in other optical receivers. In this way, 4 × 4 non-blocking optical switching for 4 parallel optical transmission channels is realized by 4 optical interrupting means (here optical modulators) per optical receiver.

Here, from the optical transmitter 10t to the optical receiver 10
Consider the loss in the optical propagation path when four parallel optical transmission channels to r are set. The optical signal from the multi-wavelength semiconductor laser array 110 suffers a distribution loss of 6 dB when combined and divided into 4 by the 4 × 4 star coupler 101. After that, it passes through the arrayed waveguide optical multiplexer / demultiplexer 130 via the optical modulator 121.
The theoretical loss at 30 is less than 3 dB. That is, in the conventional configuration, the loss of 6 dB is unavoidable in the optical combiner in the optical receiver, but the configuration of the present embodiment causes 3 dB.
Only can reduce the loss. Furthermore, if the information transmission capacity between optical transmitters and receivers is 10 Gb / s, which is the same as the conventional configuration,
In this embodiment, since 2.5 Gb / s 4-parallel optical transmission is sufficient,
Optical reception sensitivity is improved by at least 6 dB. Therefore, this embodiment is expected to equivalently improve the power budget by 9 dB as compared with the conventional configuration.

Generally, an N-wavelength semiconductor laser array,
An N × N optical network for N parallel transmission channels can be constructed by using an N × N star coupler and an N × N arrayed waveguide optical multiplexer / demultiplexer. At this time, in the conventional configuration, a loss of 10 · logN + 10 · logN [dB] was unavoidable in principle, but in the optical network of the present invention, a loss of 10 · logN + 3 [dB] or less. That is, in the optical receiver (10
A loss improvement of logN-3) [dB] is obtained. Further, under the condition that the information transmission capacity between the optical transmitters and receivers is constant, the optical reception sensitivity is improved by 10 · log N [dB] by N parallel transmission.

In the case of N = 16, for example, the present invention can reduce the theoretical loss in the optical receiver by 9 dB, and the optical reception sensitivity under the condition that the information transmission capacity between the optical transmitter and receiver is constant.
Since it can be improved by 12 dB, the loss can be improved by 21 dB equivalently. In the case of configuring a 16 × 16 optical network, the optical transmission loss is as high as 30 dB in the conventional configuration, and the information transmission capacity between optical transmitters / receivers is limited to about 10 Gb / s.
On the other hand, in the configuration of this embodiment, the optical propagation loss is 9 dB.
It will be improved to about 21 dB, and if 10 Gb / s modulation is performed per semiconductor laser, 16 parallel optical transmission will result in an information transmission capacity of 160 Gb / s between optical transceivers.
Also, the throughput of the entire optical network at this time is
It can reach 2.5 Tb / s.

As described above, in this embodiment, it is possible to increase the capacity of information transfer between optical transmitters / receivers and the capacity of the entire optical network beyond the limit of the prior art. Further, the present embodiment is characterized in that it is not necessary to temporally change the oscillation wavelength of each semiconductor laser in the multi-wavelength semiconductor laser array and the wavelength multiplexing / demultiplexing characteristic of the arrayed waveguide optical multiplexer / demultiplexer.
That is, in the present embodiment, each semiconductor laser and the arrayed waveguide optical multiplexer / demultiplexer operate perfectly in parallel, except for the alternative operation of the optical modulator array, and can be controlled very easily.

(Modification 1 of the First Embodiment) In the first embodiment, a multi-wavelength semiconductor laser array of a direct modulation system is used as an optical transmitting means for outputting a plurality of optical signals having different wavelengths in each optical transmitter. Although 110 is used, it is not limited to this. For example, one multi-wavelength semiconductor laser array of wavelengths λ1 to λ4 is provided, and the output is distributed to each optical transmitter, and each optical transmitter is provided with a light intensity modulator array instead of the multi-wavelength semiconductor laser array. The optical signal may be generated by an external modulation method.

(Modification 2 of the First Embodiment) In the first embodiment, parallel optical transmission is performed by the fiber array from the multi-wavelength semiconductor laser array of each optical transmitter to the corresponding star coupler. A low-loss optical multiplexer may be provided in the optical transmitter so as to output as a wavelength division multiplexed optical signal. In this case, the number of fibers can be reduced, and a splitter similar to the conventional configuration can be used instead of the star coupler. Further, since a plurality of optical signals transmitted in parallel propagate in a single optical fiber instead of a fiber array, there is an advantage that skew between parallel optical signals is reduced.

(Modification 3 of the First Embodiment) Referring to FIG. 1, a 4 × 4 star coupler 10 which is a plurality of light distributing means.
1, 201, 301, 401 are respectively provided as optical transmitters 10.
You may arrange | position in the vicinity of t, 20t, 30t, 40t.
Further, in FIG. 1, the optical receivers 10r, 20r, 30
The optical modulator array 120 arranged in r, 40r may be arranged near the optical transmitters 10t, 20t, 30t, 40t. These are the same topologically only by shifting the position of the device in the optical propagation path, but the optical fiber is not a star-shaped optical fiber but a star-shaped optical fiber between each optical transmitter and each optical receiver. Will be wired.

(Modification 4 of the First Embodiment) In the first embodiment, the optical modulator array 120 is used as a plurality of optical interrupting means in each optical receiver, but a semiconductor optical amplifier array is used instead. You may use. In this case, the loss in the optical propagation path can be compensated by the optical amplification effect.
Further, unlike the conventional configuration, since a plurality of wavelength-multiplexed optical signals are simultaneously incident on each optical amplifier, the pattern effect is suppressed and a high-speed optical signal can be handled. Also,
Most of the spontaneous emission light generated by the optical amplifier is blocked by the wavelength router (the arrayed-waveguide optical multiplexer / demultiplexer 130) in the next stage, so that the SN ratio at the time of receiving the signal light is also small. In addition, as an optical disconnecting means, if the frequency of changing the optical transmission channel setting between optical transmitters and receivers is low, a mechanical optical switch,
A waveguide optical switch using a thermo-optical effect, a liquid crystal optical shutter, or the like can be used.

(Variation 5 of First Embodiment) In the first embodiment, the arrayed waveguide optical multiplexer / demultiplexer 130 having the wavelength routing characteristic shown in FIG. 3 is used as the wavelength router, but it is shown in FIG. Similar functions can be realized by combining a plurality of optical demultiplexers 51 to 54 and a plurality of optical multiplexers 55 to 58. Optical demultiplexers 51-54 and optical multiplexers 55-55
The wiring between the wiring 58 and the wiring 58 corresponds to the wavelength routing characteristic shown in FIG.

(Modification 6 of First Embodiment) The wavelength routing characteristic of the wavelength router is not limited to the characteristic shown in FIG. 3, and the characteristic shown in FIG. 5 constitutes a similar optical receiver and optical network. can do. In addition,
As shown in FIGS. 3 and 5, a matrix in which different symbols (here, λ1 to λ4) are arranged in the same row or the same column is called a Latin square, and it is known that there are many other squares. (Reference: R. Barry, et al., "LatinRoute
rs, Desine and Implementation ", IEEE J. Lightwave T
echnol., vol.11, no.5 / 6, pp.891-899, 1993), any of which may be used.

Further, an optical receiver and an optical network having the same effect can be constructed by using a wavelength router having a characteristic that does not satisfy the Latin square, for example, a characteristic shown in FIG. However, in this case, it is necessary to preset the transmission wavelength of the multi-wavelength semiconductor laser array so as to be partially different for each optical transmitter in accordance with the wavelength routing characteristic.

(Modification 7 of the First Embodiment) In the first embodiment, the case where the parallelism in information transmission between the optical transmitters and receivers and the maximum number of optical transmitters and receivers that can be accommodated is the same. It is not limited. For example, in a 2 × 2 optical network that performs 4-parallel optical transmission, each optical transmitter is composed of a 4-wavelength semiconductor laser array, and each optical receiver is composed of an optical modulator array consisting of two optical modulators and a 2 × 2 optical modulator array. A four-array waveguide optical multiplexer / demultiplexer and a photodetector array composed of four photodetectors may be used, and each optical transmitter / receiver may be connected using a plurality of 4 × 2 star couplers. At this time, as the 2 × 4 arrayed waveguide optical multiplexer / demultiplexer, for example, the input port I2 of the 4 × 4 arrayed waveguide optical multiplexer / demultiplexer having the wavelength routing characteristic shown in FIG.
I3 and output ports J1 to J4 may be used.

For example, in a 4 × 4 optical network for performing two parallel optical transmissions, each optical transmitter is composed of a two-wavelength semiconductor laser array, and each optical receiver is an optical modulator array consisting of four optical modulators. A 4 × 2 arrayed waveguide optical multiplexer / demultiplexer and a photodetector array composed of two photodetectors may be used, and each optical transmitter / receiver may be connected using a plurality of 2 × 4 star couplers.
At this time, as the 4 × 2 arrayed waveguide optical multiplexer / demultiplexer, for example, the input ports I1 to I4 and the output port J of the 4 × 4 arrayed waveguide optical multiplexer / demultiplexer having the wavelength routing characteristics of FIG.
2, J3 may be used. The 4 × 4 arrayed waveguide optical multiplexer / demultiplexer having the characteristics shown in FIG. 7 can be realized by being configured so as to simultaneously extract a plurality of orders of arrayed waveguide diffracted light. Here, K + 1 order diffracted light, K order diffracted light, and K + 1 order diffracted light are used. Alternatively, even if the arrayed waveguide optical multiplexer / demultiplexer having the wavelength routing characteristic shown in FIG. 3 is used, if the transmission wavelength of the multi-wavelength semiconductor laser array is preset so as to be partially different for each optical transmitter, two parallel optical transmissions are performed. Do 4x
Four optical networks can be configured.

(Variation 8 of the First Embodiment, Others) First
In the embodiment, the parallel optical transmission channel can be set between all the optical transmitters / receivers, but if it is known in advance that communication between specific optical transmitters / receivers is not required, It is possible to reduce the number of distributions in the star coupler and the number of light interrupting means.

Further, in the first embodiment, the case where the number of optical transmitters and the number of optical receivers are the same is shown. However, for example, an optical transmitter that does not require information transmission may be deleted or information reception may be required. You may remove the missing optical receiver. That is, the numbers of optical transmitters and optical receivers do not necessarily have to match. Further, one or a plurality of communication paths that are transmitted in parallel between the optical transmitters / receivers may be used for transmitting, for example, clock information or control information. As an example thereof, a case in which an optical network for 4-bit parallel signal transmission composed of a 2-bit parallel signal, a parity signal, and a clock signal in the configuration of FIG. 1 is used will be described below as a second embodiment.

(Second Embodiment) FIG. 8 shows a second embodiment of the optical network of the present invention. Here, the same reference numerals are given to the portions corresponding to the respective portions of FIG. 1, and the description thereof will be omitted. The feature of this embodiment is that each optical transmitter is provided with an encoder 15 and a matrix switch 16, and each optical receiver is provided with a flip-flop 17 and a decoder 18.
For the sake of convenience, the optical transmitter and the optical receiver are combined to form modules 10 ', 20', 30 'and 40'.

Between each module, 4 parallel data in which a clock and a parity for error detection are added to 2 parallel transmission data is transmitted. For example, in the module 10 ', the 2 parallel transmission data becomes 3 parallel data to which the parity signal is added by the encoder 15 synchronized with the clock, and the 4 series data string combined with the clock is input to the matrix switch 16. Here, the matrix switch 16 converts the input four-series data string into four semiconductor lasers 111 to 11
Divide into 4. At this time, the wiring in the matrix switch 16 of each module is fixedly set as shown in FIG. That is, the clock signal becomes an optical signal of wavelength λ1 in the module 10 ', and the module 20'
In the module 30 'becomes an optical signal of wavelength λ4, in the module 30' it becomes an optical signal of wavelength λ3,
It becomes the optical signal of.

On the other hand, the receiver array 140 of each module
No matter which module the wavelength-multiplexed optical signal from the optical modulator array 120 is selected in the optical receiver 141, the clock signal is always received by setting the matrix switch 16 of each module as shown in FIG. . For example, in the module 10 ′, the light receiver 141 receives the clock signal, and the flip-flop 17 is used by using this clock.
Identifies and reproduces the three parallel signals received by the photodetectors 142 to 144 collectively. Here, since the parity signal is always received by the light receiver 144 as in the case of the clock signal, the decoder 18 uses this to perform error detection by the parity check of the two parallel signals. As a result, the error-free two parallel signals and the clock are output as the reception data of the module 10 '.

In the second embodiment described above, parallel optical transmission with a clock signal and a parity signal added is performed between modules, so that in addition to the advantages of the first embodiment, clock extraction and high-speed phase synchronization are achieved. It is possible to eliminate the need for complicated circuits or reduce the number. That is, by providing parallel signal processing means such as collective identification reproduction of parallel signals and error detection by parity signals, an optical network of low cost and high reliability can be constructed (claim 2).

(Modification 1 of Second Embodiment) In the second embodiment, the clock signal received by the light receiver 141 is used as it is as the clock signal of the flip-flop 17, but a phase locked loop (PLL) or the like is used. To recover a more stable clock signal and then to flip-flop 17
May be supplied. Further, it may be configured such that a timing extraction circuit is provided without transmitting the clock signal. That is, timing extraction may be performed from one of the received four parallel optical signals to reproduce the clock signal, and identification reproduction (parallel signal processing) may be performed together with other parallel optical signals. In addition,
When the skew between parallel optical signals becomes a problem, it is necessary to adjust the clock phase for each signal, but in this case as well, the reference clock signal is regenerated from a part of the parallel signals. Since it is used, it can be regarded as a form of parallel signal processing.

(Modification 2 of the Second Embodiment) In the second embodiment, the flip-flop 17 for collective identification reproduction and the decoder 18 for error detection are used as the parallel signal processing means. A decoder or the like for decoding a signal that has been encoded for skew reduction may be used.

(Modification 3 of the Second Embodiment) In the second embodiment, the matrix switch 16 is used on the transmission side so that the light receiver 141 always receives the clock signal regardless of the communication destination module. Although the transmission wavelength of the clock signal is selected, a matrix switch may be provided between the receiver array 140 on the receiving side and the flip-flop 17 for switching. However, in this case, it is necessary to change the setting of the matrix switch according to the switching of the communication partner in the optical modulator array 120.

[0050]

As described above, the optical receiver of the present invention and the optical network using the same can be realized by combining the parallel optical transmission technique and the optical wavelength multiplexing technique in the optical network in which a plurality of optical transceivers are connected. The loss in the optical receiver can be greatly reduced. further,
The information transmission rate per light wave can be kept low,
It is possible to increase the capacity of information transfer between optical transceivers and the throughput of the entire optical network.

[Brief description of drawings]

FIG. 1 is a first of the optical network and optical receiver of the present invention.
FIG.

FIG. 2 is a diagram showing a configuration of an arrayed waveguide optical multiplexer / demultiplexer.

FIG. 3 is a diagram showing wavelength routing characteristics of an arrayed waveguide optical multiplexer / demultiplexer.

FIG. 4 is a diagram showing a configuration of another wavelength router having the wavelength routing characteristic of FIG.

FIG. 5 is a diagram showing an example of another wavelength routing characteristic.

FIG. 6 is a diagram showing an example of another wavelength routing characteristic.

FIG. 7 is a diagram showing an example of wavelength routing characteristics of a 4 × 2 arrayed waveguide optical multiplexer / demultiplexer.

FIG. 8 shows a second embodiment of the optical network of the present invention.

FIG. 9 is a diagram showing a setting state of a matrix switch of each module.

FIG. 10 is a diagram for explaining the architecture of a large capacity ATM switch.

FIG. 11 is a diagram showing a configuration of a conventional optical receiver and an optical network.

[Explanation of symbols]

1t, 2t, 3t, 4t, 10t, 20t, 30t, 4
0t optical transmitter 1r, 2r, 3r, 4r, 10r, 20r, 30r, 4
0r optical receiver 10 ', 20', 30 ', 40' module 11 semiconductor laser 13 optical combiner 14 photodetector 15 encoder 16 matrix switch 17 flip-flop 18 decoder 100, 200, 300, 400 splitter 101, 201, 301, 401 4 × 4 star coupler 110 multi-wavelength semiconductor laser array 111, 112, 113, 114 semiconductor laser 120 optical modulator array 121, 122, 123, 124 optical modulator 130 array waveguide optical multiplexer / demultiplexer 131 input waveguide Array 132 Input-side slab waveguide 133 Waveguide array 134 Output-side slab waveguide 135 Output waveguide array 140 Optical receiver array 141, 142, 143, 144 Optical receiver

Claims (3)

[Claims] 1. A WDM optical signal comprising: a plurality of optical interrupting means for inputting a plurality of wavelength multiplexed optical signals and turning them on / off respectively; and a plurality of input ports connected to the plurality of optical interrupting means. A wavelength router that determines the wavelengths to be demultiplexed into a plurality of output ports according to the input port to which is input, and a plurality of optical receiving means connected to the plurality of output ports of the wavelength router. An optical receiver having a configuration in which one of the connecting / disconnecting means is turned on and the other is turned off. 2. The optical receiver according to claim 1, further comprising parallel signal processing means connected to the plurality of optical receiving means. 3. A plurality of optical transmitters each having an optical transmitting means for outputting a plurality of optical signals having different wavelengths, and a plurality of optical signals output from the optical transmitter are wavelength-multiplexed and the wavelengths thereof are multiplexed. The light according to claim 1 or 2, wherein a plurality of optical distribution means corresponding to each optical transmitter for distributing a plurality of multiplexed optical signals, and a wavelength-multiplexed optical signal output from each of the plurality of optical distribution means are input. An optical network comprising a receiver.