JP2012244328A - Optical transmission device and optical transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission device and optical transmission method capable of reducing power consumption.SOLUTION: An optical transmission device includes: OEs 12_1 to 12_N for photoelectrically converting the headers of IP (Internet protocol) packets; header processing parts 13_1 to 13_N for acquiring header information; a collision detection destination control part 123 for determining output routes in accordance with destinations included in the header information; an optical switch 117 for outputting payloads to the determined routes; header optical signal generation parts 15_1 to 15_M for converting the header information into optical signals; and confluence parts 81_1 to 81_M for generating IP packets by coupling the headers with the payloads.

Description

  The present invention relates to an optical transmission apparatus and an optical transmission method for realizing ultra-low power consumption in an ultra-high speed IP (Internet Protocol) network.

  In recent years, the spread of the Internet has been remarkable, and the total traffic flowing through the network continues to increase. If Ogasawara, the National Institute of Science and Technology Policy continues to increase communication traffic at the current pace, the power consumption of the router alone will be eight times that of 2006 in 2010 and 600 times that in 2020 (447.8 billion). kWh / year) is predicted to be necessary (see, for example, Non-Patent Document 1). This corresponds to reaching 49% of the total domestic power generation (920.0 billion kWh / year) in 2006, and it can be said to be a critical situation considering the current situation where it is difficult to expect a rapid increase in power generation. As Ogasawara points out, it is necessary to work on lowering the voltage of LSI (Large Scale Integration), but even if this works, the problem can be solved completely by lowering the voltage of LSI alone. I can't say that.

  On the other hand, network (photonic network) technology for transferring optical signals as they are is being put into practical use. In this method, a wavelength path is set between nodes separately from the IP network, and switching is performed in units of this path. Photonic networks can be classified into four types: an optical path switching system, an optical burst switching system, an optical slot switching system, and an optical packet switching system (see, for example, Non-Patent Documents 2 to 4).

  NTT has already introduced a photonic network as a wavelength multiplexing ring network. Extending this to a mesh network corresponds to the optical path switching method. This eliminates the need for an IP router that performs a relay operation, and thus power consumption is reduced. However, since an edge node requires an ultra-high-speed IP router, a significant power reduction cannot be expected.

  What develops this optical path switching system is an optical burst switching system or an optical slot switching system. In either case, a node for bundling packets into a burst signal or synchronizing as an optical slot is required, and the power load increases, and it can be said that the problem is not solved.

  Furthermore, even in the optical packet switching method, conventionally, the optical packet switching node follows the current packet format of the electronic router in which the header and payload are continuously byte-multiplexed at the same bit rate, and should it be processed originally? In order to receive a 20-byte (IPv4) header, an ultra-high speed LSI of several tens of gigabits per second is required. The problem due to this is not only an increase in cost, but also the disadvantage of consuming a large amount of power for operating a high-speed circuit is not sufficiently solved.

Atsushi Ogasawara “Energy Issues in Information and Communications-Required Energy Savings in Communication Infrastructure” Ministry of Education, Culture, Sports, Science and Technology, Science and Technology Policy Research Institute, Science and Technology Trend Research Center, Science and Technology Trend 6, June 2006 (http: //www.nistep. go.jp/achiev/ftx/jpn/stfc/st063j/0606_03_featurearticles/0606fa01/2006066_fa01.html) Edited by Kenichi Sato and Masafumi Koga, "Broadband Optical Networking-Photonic Network", Section 7.1.1, pp. 241-242, IEICE (2003) I. Chlamtac, A.M. Fumagalli, G .; Wedzinga, “Slot Routing as a Solution for Optically Transparent Transparent WDM Wide Area Networks.” Photonic Network Communications 1.1 (June), pp. 196 9-21 (1996) Hiroaki Harai "Expectations for Optical Buffer Technology and Current Status of Control Technology" November 30, 2005 Innovation for New Generation Optical Communication First Optical Buffer Mini Study Group (http://www2.nict.go.jp/w/ w112 / member / obuf-workshop-0511-harai.pdf [acquired 2011/03/28])

  An object of the present invention is to provide an optical transmission apparatus and an optical transmission method capable of reducing power consumption.

  To achieve the above object, an optical transmission apparatus according to the present invention includes a photoelectric conversion unit that photoelectrically converts an IP packet header, and header processing that acquires header information of the IP packet using an output signal of the photoelectric conversion unit. A destination control unit that determines an output route according to a destination included in the header information acquired by the header processing unit, and a route that the destination control unit determines with the payload of the IP packet as an optical signal A payload output unit that outputs the header information, a header optical signal generation unit that converts the header information acquired by the header processing unit into an optical signal, a header from the header optical signal generation unit, and a payload output from the payload output unit An IP packet output unit for outputting to the road.

  Since the optical transmission apparatus of the present invention includes the photoelectric conversion unit and the header processing unit, it is possible to detect a route according to the destination of the IP packet without converting the payload into an electrical signal. Since the optical transmission apparatus according to the present invention includes the payload output unit and the destination control unit, the payload can be output to the route according to the destination as the optical signal. Since the optical transmission device of the present invention includes a header optical signal generation unit and an IP packet output unit, the optical transmission device generates an optical signal of an IP packet including a header and a payload, and outputs the IP packet to a route according to the destination can do. As described above, the optical transmission apparatus of the present invention does not need to keep the high-speed circuit operating, and does not need a node for bundling packets into a burst signal or synchronizing as an optical slot. High-speed transmission can be performed.

In the optical transmission apparatus of the present invention, an optical signal having the optical signal level of the header of the IP packet is removed, and is larger than the optical signal level of the header of the IP packet and smaller than the optical signal level of the payload of the IP packet. A payload extraction unit that allows an optical signal having an optical signal level to pass therethrough may be further provided before the payload output unit or between the payload output unit and the IP packet output unit.
When the optical signal level of the header and the optical signal level of the payload are different, the optical signal of the payload can be extracted according to the present invention.

In the optical transmission apparatus of the present invention, the bit rate of the header of the IP packet may be lower than the bit rate of the payload.
Since the payload bit rate and the header bit rate are different, the header optical signal and the payload optical signal can be separated using the clock frequency of the optical signal.

In the optical transmission device of the present invention, an optical branching unit that branches the IP packet, a clock monitor that detects a clock frequency of one optical signal from the optical branching unit, and a clock frequency detected by the clock monitor And an input switching unit that outputs the other optical signal from the optical branching unit to the photoelectric conversion unit or the payload output unit.
Since the optical transmission device of the present invention includes the optical branching unit, the clock monitor, and the input switching unit, the optical signal of the header and the optical signal of the payload can be separated using the clock frequency of the optical signal. it can.

In the optical transmission apparatus of the present invention, the IP packet is output to one input port of a 3 dB coupler whose output port is connected to both ends of the nonlinear optical fiber, and an optical signal from the one input port of the 3 dB coupler. An optical circulator that outputs to the payload output unit, the one input port is connected to the optical circulator, the other input port is connected to the photoelectric conversion unit, and two output ports are connected to both ends of the nonlinear optical fiber. An optical signal that is connected and input to the one input port is input to both ends of the nonlinear optical fiber, and an optical signal that circulates around the nonlinear optical fiber and returns to the two output ports is multiplexed. Both ends are connected to the 3 dB coupler that outputs to the one input port and the other input port, and the output port of the 3 dB coupler. And a nonlinear optical fiber may be provided with a.
Since the optical transmission apparatus of the present invention includes an optical circulator, a 3 dB coupler, and a nonlinear optical fiber, the optical signal of the header and the optical signal of the payload can be separated using the nonlinear refractive index of the nonlinear optical fiber.

  In the optical transmission apparatus according to the present invention, the IP packet has a duty ratio of a pulse of an optical signal in a header of the IP packet, rather than a product of a duty ratio of a pulse in the payload of the IP packet, an optical pulse peak power, and a time slot. The product of the optical pulse peak power and the time slot may be smaller.

In the optical transmission device of the present invention, the payload output unit may be a self-holding optical switch that maintains a connection state without power consumption while the payload is passing. In this case, the self-holding optical switch may perform switching by switching between transmission and reflection in the phase change material using a refractive index change accompanying a temperature change in the phase change material.
According to the present invention, since the driving timing of the payload output unit can be reduced to only the start point and end point of the packet, the power consumption of the payload output unit can be reduced.

  The optical transmission method of the present invention is a destination control step of photoelectrically converting an IP packet header to obtain header information of the IP packet, and determining an output route according to a destination included in the obtained header information; The payload output step for outputting the payload of the IP packet to the route determined in the destination control step, and the header information acquired in the destination control step is converted into an optical signal, and the converted header and the payload output step are output. An IP packet output step for outputting the received payload to an output route.

  Since the destination control step is included, the route corresponding to the destination of the IP packet can be detected without converting the payload into an electrical signal. Since the payload output step is included, the payload can be output to the route according to the destination as an optical signal. Since the IP packet output step is included, an optical signal of an IP packet including a header and a payload can be generated, and the IP packet can be output to a route according to the destination. As described above, the optical transmission method of the present invention does not need to keep the high-speed circuit operating, and does not require a node for bundling packets into a burst signal or synchronizing as an optical slot. High-speed transmission can be performed.

In the optical transmission method of the present invention, in the destination control step, an optical signal having an optical signal level in the header of the IP packet is removed, and is larger than the optical signal level in the header of the IP packet and the payload of the IP packet The payload may be extracted by using a limiter amplifier circuit that passes an optical signal having an optical signal level smaller than the optical signal level.
When the optical signal level of the header and the optical signal level of the payload are different, the optical signal of the payload can be extracted according to the present invention.

In the optical transmission method of the present invention, the bit rate of the header of the IP packet may be lower than the bit rate of the payload.
Since the payload bit rate and the header bit rate are different, the header optical signal and the payload optical signal can be separated using the clock frequency of the optical signal.

In the optical transmission method of the present invention, in the destination control step, the IP packet is branched, the clock frequency of one branched optical signal is detected, and the other branched optical signal is detected according to the detected clock frequency. The IP packet header and payload may be separated.
According to the present invention, the optical signal of the header and the optical signal of the payload can be separated using the clock frequency of the optical signal.

In the optical transmission method of the present invention, in the destination control step, the IP packet is input from both ends of the nonlinear optical fiber, the IP packets after passing through the nonlinear optical fiber are combined with each other, and the combined optical signal May be separated into a header and a payload of the IP packet.
According to the present invention, the optical signal of the header and the optical signal of the payload can be separated using the nonlinear refractive index of the nonlinear optical fiber.

  In the optical transmission method of the present invention, the IP packet has a duty ratio of a pulse of an optical signal in a header of the IP packet rather than a product of a duty ratio of a pulse in the payload of the IP packet, an optical pulse peak power, and a time slot. The product of the optical pulse peak power and the time slot may be smaller.

In the optical transmission method according to the present invention, in the payload output step, a self-holding optical switch that maintains a connection state without power consumption while the payload is passing is output to the path determined in the destination control step. May be. In this case, the self-holding optical switch may perform switching by switching between transmission and reflection in the phase change material using a refractive index change accompanying a temperature change in the phase change material.
According to the present invention, since the driving timing of the payload output unit can be reduced to only the start point and end point of the packet, the power consumption of the payload output unit can be reduced.

  The above inventions can be combined as much as possible.

  According to the present invention, it is possible to provide an optical transmission device and an optical transmission method capable of reducing power consumption.

1 illustrates an example of an optical transmission apparatus according to a first embodiment. The structural example of the conventional IP packet is shown. The structural example of the IP packet which concerns on this embodiment is shown. 4 illustrates an example of an optical transmission apparatus according to a second embodiment. The specific example of the optical branching part which concerns on Embodiment 3 is shown. 9 shows a header / payload separation circuit according to a fourth embodiment. 10 shows a header / payload separation circuit according to a fifth embodiment. The operation of the self-holding optical switch when the self-holding optical switch transmits an optical signal is shown. The operation of the self-holding optical switch when the self-holding optical switch reflects an optical signal is shown. Comparison of power consumption timing between electrical switching and optical switching.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 1 shows an example of an optical transmission apparatus according to the embodiment. The optical transmission apparatus according to the present embodiment has an arbitrary number M of output routes # 1 to #M, and outputs an input IP packet to a route according to a destination. Specifically, the optical transmission apparatus according to the present embodiment includes an optical branching unit 11, a photoelectric conversion unit 12, a header processing unit 13, a destination control unit 14, a header optical signal generation unit 15, and a payload extraction unit. 16, a payload output unit 17, and an IP packet output unit 18.

The optical transmission method according to this embodiment includes a destination control step, a payload output step, and an IP packet output step in order.
In the destination control step, the optical transmission apparatus according to the present embodiment operates as follows.
The optical branching unit 11 branches the optical signal, and outputs one to the photoelectric conversion unit 12 and the other to the payload extraction unit 16. The photoelectric conversion unit 12 photoelectrically converts the header of the IP packet. The header processing unit 13 acquires the header information of the IP packet using the output signal of the photoelectric conversion unit 12. The destination control unit 14 determines an output route according to the destination included in the header information acquired by the header processing unit 13.

In the payload output step, the optical transmission apparatus according to this embodiment operates as follows.
The payload extraction unit 16 extracts the payload as an optical signal from the IP packet. The payload output unit 17 outputs the payload of the IP packet to a route determined by the destination control unit 14.

In the IP packet output step, the optical transmission apparatus according to this embodiment operates as follows.
The header optical signal generation unit 15 converts the header information acquired by the header processing unit 13 into an optical signal. The IP packet output unit 18 combines the header from the header optical signal generation unit 15 and the payload from the payload output unit 17 to generate an IP packet and outputs it to the output route. Thereby, an IP packet can be output to the route according to the destination.

The optical transmission apparatus according to the present embodiment photoelectrically converts only the header of the input IP packet, receives it electronically, interprets the destination, determines the path after the reproduced header. Output. For this reason, the optical transmission apparatus according to the present embodiment does not need to keep operating the high-speed circuit, and does not need a node for bundling packets into burst signals or synchronizing them as optical slots, and the transmission apparatus handles them. There is no need to change the logical configuration of the IP packet. Therefore, the optical transmission apparatus according to the present embodiment can realize an ultra-high speed transmission apparatus with low power consumption. This has the advantage of being able to CO ₂ generation is also suppressed at the time of power generation.

  Here, it is preferable that the optical transmission device according to the present embodiment easily separates the header and the payload in the state of the optical signal in order to maintain the payload as an optical signal and convert only the header into an electric signal.

  In the conventional IP packet, as shown in FIG. 2, the header bit rate is changed in accordance with the payload bit rate. On the other hand, in the IP packet according to the present embodiment, as shown in FIG. 3, the header with a limited amount of information is separated from the payload speed, and is about several gigabits per second that can be processed by a low power consumption CMOS LSI. It is preferable that only a payload that is increased in speed according to traffic demand is serially transmitted with an ultrahigh-speed pulse train. Furthermore, the IP packet preferably has a lower header bit rate than the payload bit rate.

  Furthermore, since the time width of one bit (time slot: T [s]) is wider than the payload of the header, the signal-to-noise ratio (SNR) of the pulse is maintained even if the pulse peak value P [W] is low. . If the time slot, the pulse peak, and the pulse duty ratio (D [%]) are the same, the mutual SNR is the same.

  Furthermore, since the payload is transmitted without being replayed and relayed, the header is terminated at each node, so the SNR of the header does not need to be better than the SNR of the payload. For this reason, the product of T, P, and D may be lower than that of the payload in the header. That is, the IP packet has a duty ratio D of the pulse of the optical signal in the header of the IP packet and an optical pulse peak power P, rather than the product of the pulse duty ratio D, the optical pulse peak power P, and the time slot T in the payload of the IP packet. And the time slot T may be smaller.

  In this case, the payload extraction unit 16 can extract the payload as an optical signal from the IP packet using the limiter amplifier circuit. For example, the payload extraction unit 16 removes an optical signal having the optical signal level of the header of the IP packet, and has an optical signal level higher than the optical signal level of the header of the IP packet and smaller than the payload. Let the signal pass.

  In the present embodiment, the payload extraction unit 16 may be connected between the optical branching unit 11 and the payload output unit 17, or connected between the payload output unit 17 and the IP packet output unit 18. Also good.

(Embodiment 2)
FIG. 4 shows an example of an optical transmission apparatus according to the second embodiment. The optical transmission apparatus according to the present embodiment has an arbitrary number N of input routes # 1 to #M and an arbitrary number M of output routes # 1 to #M, and transmits an IP packet. The signal is output to the route according to the destination. Here, the optical transmission apparatus according to the present embodiment employs a method of avoiding packet collision by detour routing without having an optical memory buffer. In each node, the path is selected by receiving and processing only the header, and the payload is switched to the optical pulse signal using the self-holding optical switch.

  Specifically, the optical transmission apparatus according to the present embodiment includes optical branching units 11_1 to 11_N, OEs 12_1 to 12_N as photoelectric conversion units 12, header processing units 13_1 to 13_N, and collision detection as a destination control unit 14. Destination control unit 123, header optical signal generation units 15_1 to 15_M, limiter amplifier circuits 116_1 to 116_N as payload extraction unit 16, packet monitors 119_1 to 119_N, optical switch 117 as payload output unit 17, and optical switch A monitoring control unit 121, delay control units 120_1 to 120_M, and merging units 81_1 to 81_M as the IP packet output unit 18 are provided. The header optical signal generation units 15_1 to 15_M include header generation units 51_1 to 51_M, encoding units 52_1 to 52_M, and EOs 53_1 to 53_M.

In the destination control step, the optical transmission apparatus according to the present embodiment operates as follows.
The optical branching units 11_1 to 11_N branch the input packet into two while maintaining the optical signal. One is OE-converted by OE12_1 to 12N, and a header is detected. The header processing units 13_1 to 13_N recognize the packet header and notify the collision detection destination control unit 123.

  The limiter amplifier circuits 116_1 to 116_N delete the low-level header, pass only the payload, and suppress the amplitude noise of the payload. The packet monitors 119_1 to 119_N monitor the bit rate of the payload and the packet duration by monitoring the clock level of the packet, and notify the collision detection destination control unit 123.

  The collision detection destination control unit 123 detects the packet input from each of the input routes # 1 to #N and the length thereof, schedules the destination, and instructs the optical switch monitoring control unit 121. For example, when packets collide with the same output route, the output route of the detour route is selected and scheduled to be output. If there is a collision in all detour routes, schedule to discard the packet. The destination control step is thus completed.

In the payload output step, the optical transmission apparatus according to this embodiment operates as follows.
The optical switch monitoring controller 121 controls the operation of the optical switch 117 according to an instruction from the collision detection destination controller 123. The optical switch 117 outputs the input optical payload to an output route controlled by the optical switch monitoring control unit 121. For example, the optical switch 117 outputs the payload of the input route # 1 to the output route #M. In this case, the payload is input to the delay control unit 120_M. This is the end of the payload output step.

  Here, it is preferable that the optical switch 117 uses the self-holding optical switches 71_1 to 71_NM that maintain the connection state without power consumption while the optical payload passes. Thereby, low power consumption of the optical switch 117 can be realized together with high extinction ratio performance.

In the IP packet output step, the optical transmission apparatus according to this embodiment operates as follows.
The header generation units 51_1 to 51_M generate a header for the output route. The encoding units 52_1 to 52_M encode the header generated by the header generation units 51_1 to 51_M. The EOs 53_1 to 53_M convert electrical signals from the encoding units 52_1 to 52_M into optical signals.

  When the payload transit time is shorter than the packet header processing time and the header precedence cannot be maintained, the delay control units 120_1 to 120_M delay the payload and secure the header precedence. Junction units 81_1 to 81_M encode the header through a transmission path. The header and payload are merged and sent to the transmission path. A junction circuit or an optical switch is used. This completes the IP packet output step.

  The optical transmission apparatus according to the present embodiment further has an edge router function for generating or receiving a packet. The edge router function includes, for example, an input port 141, a packet multiplexing generation circuit 142, a transmission path encoding unit 143 that encodes a payload, a transmission path decoding unit 144, a packet reception separation circuit 145, and an output. A port 146. The encoding method of the transmission path encoding unit 143 is preferably determined independently of the header unit. For example, OTU (Optical Transport Unit) 1, STM (Snchronous Transport Module) -16, or GbE (Gigabit Ethernet (registered trademark)) is used. Use.

As described above, the optical transmission apparatus according to the present embodiment is capable of ultra-high-speed IP with low power consumption by fundamentally reviewing the physical implementation without changing the logical configuration of the IP packet handled by the transmission apparatus. A router can be realized. This makes it possible to CO ₂ generation is also suppressed at the time of power generation.

(Embodiment 3)
The optical transmission apparatus according to the third embodiment includes an optical branching unit 11 using a nonlinear fiber loop mirror type optical circuit. FIG. 5 shows a specific example of the optical branching unit according to the third embodiment. The optical branching unit 11 according to this embodiment includes an optical amplifier 122, an optical circulator 124, a 3 dB coupler 125, and a nonlinear optical fiber 126. The optical amplifier 122 amplifies the optical signal. The optical circulator 124 outputs the optical signal from the optical amplifier 122 to the 3 dB coupler 125. The 3 dB coupler 125 inputs an optical signal to both ends of the nonlinear optical fiber 126. Then, the 3 dB coupler 125 multiplexes the two optical signals that have circulated through the nonlinear optical fiber 126 and branches them into two, outputs one to the optical circulator 124, and outputs the other to the OE 12. The optical circulator 124 outputs the optical signal from the 3 dB coupler 125 to the optical switch 117.

  Since the branching ratio of the 3 dB coupler 125 in FIG. 5 is not exactly 50%: 50% in reality, the nonlinear refractive index felt by the clockwise and counterclockwise pulse train in the nonlinear optical fiber 126 is slightly different. As a result, the interference between the fiber loop transmitted light pulses that circulate in the nonlinear optical fiber 126 is different from the linear case, and there is a condition that the payload pulse train is not output to the header output port, so that the header and the payload can be separated.

(Embodiment 4)
The optical transmission apparatus according to the fourth embodiment includes a header / payload separation circuit including an optical switch. FIG. 6 shows a header / payload separation circuit according to this embodiment. The header / payload separation circuit according to this embodiment is connected between the optical branching unit 11, the OE 12, and the optical switch 117, and includes a clock monitor 22 and an optical switch 24 as an input switching unit.

The optical transmission apparatus according to the present embodiment operates as follows in the destination control step.
The input IP packet is first branched by the optical branching unit 11, and one is input to the clock monitor 22. The clock monitor 22 detects the clock frequency of the optical signal from the optical branching unit 11. The optical switch 24 outputs the optical signal from the optical branching unit 11 to the OE 12 or the optical switch 117 according to the clock frequency detected by the clock monitor 22. The subsequent operation is the same as that of the second embodiment.

  When the packet configuration shown in FIG. 2 is taken, the clocks of the header and the payload are different. Using this fact, it is determined that the header is used when the clock rate is low and the payload is used when the clock rate is high. When the one-to-two optical switch 24 is driven so as to output to the OE 12 in the case of a low clock rate and to the optical switch 117 in the case of a high clock rate, the header and the payload can be separated. However, when the time required for the detection operation of the clock monitor 22 is large, an optical delay device 23 may be inserted between the optical branching unit 11 and the optical switch 24, but this is not necessary when the operation time can be ignored. . The optical branching unit 11 may be an optical tap.

(Embodiment 5)
The optical transmission apparatus according to the fifth embodiment includes the header / payload separation circuit described in the fourth embodiment between the optical switch 117 described in the second embodiment and the merging units 81_1 to 81_M. FIG. 7 shows a header / payload separation circuit according to this embodiment. The header / payload separation circuit according to the present embodiment includes an optical branching unit 31, a clock monitor 32, and an optical switch 34.

  The optical branching unit 31 branches the optical signal from the optical switch 117, outputs one to the clock monitor 32, and outputs the other to the optical switch 34. The clock monitor 32 detects the clock frequency of the optical signal from the optical branching unit 31. The optical switch 34 includes two input ports and one output port. One of the input ports is connected to the optical branching unit 31, the other input port is connected to the EO 53, and the output port is connected to the output route. As in the fourth embodiment, the optical switch 34 allows the optical signal from the optical branching unit 31 to pass when the clock rate is high, and allows the optical signal from the EO 53 to pass when the clock rate is low.

  In the present embodiment, the header generation unit 51 may generate a header using the drive signal from the clock monitor 32, and the encoding unit 52 may encode using the drive signal from the clock monitor 32. In addition, the optical switch 34 is controlled so as to delay the optical signal by using the optical delay device 33 for the time required for header generation and encoding, and to output the optical signal from the EO 53 prior to the payload. The optical branching unit 31 may be an optical tap.

(Embodiment 6)
The optical transmission apparatus according to the sixth embodiment uses a self-holding total reflection optical switch that uses a phase change material in order to realize low power consumption of the optical switch 117 described in the second embodiment together with high extinction ratio performance. . FIG. 8 shows the operation of the self-holding optical switch when the self-holding optical switch transmits an optical signal. FIG. 9 shows the operation of the self-holding optical switch when the self-holding optical switch reflects an optical signal.

The refractive index n ₂ of the phase change material 171 is selected to be larger than the refractive index (n ₁ ) of the upper and lower media sandwiching it. Further, when the optical signal is transmitted (off), the incident angles α and β are set to the Brewster angles as shown in FIG. 8, so that no light is output to the reflection port and all is output to the output port A. The On the other hand, in order to turn on the switch, as shown in FIG. 9, the area around the point where the light beam exits the phase change material 171 is locally heated with a laser or the like to increase the refractive index. In this way, all light signals are output to the output port B in principle by totally reflecting the light beam.

  In this way, by constructing and operating the optical switch 117 using a self-holding optical switch, the characteristic is that the extinction ratio is infinite, such that there is no reflected light component when passing and no transmitted light component when totally reflected. Can be achieved. This has the advantage that the crosstalk quality of the signal can be kept good.

Further, as shown in FIG. 10, by adopting the self-holding type, the drive timing of the optical switch 117 is only required at the start point and end point of the packet, and power is supplied at the change points of all bits in the packet passing therethrough. Compared to the current CMOS type electronic switch-based electronic router that consumes, the switch driving opportunity is greatly reduced (on average 1/3200). Thereby, it is possible to realize an ultra-high speed IP router with low power consumption, and to suppress generation of CO ₂ when generating power.

  The present invention can be applied to the information communication industry.

11, 11_1 to 11_N, 31: optical branching unit 12: photoelectric conversion units 12_1 to 12_N: OE
13, 13_1 to 13_N: header processing unit 14: destination control unit 15, 15_1 to 15_M: header optical signal generation unit 16: payload extraction unit 17: payload output unit 18: IP packet output unit 22, 32: clock monitor 23, 33 : Optical delay units 24, 34: Optical switches 51, 51_1 to 51_M: Header generation units 52, 52_1 to 52_M: Encoding units 53, 53_1 to 53_M: EO
71_11, 71_1E, 71_1M, 71_N1, 71_NE, 71_NM, 71_E1, 71_EE, 71_EM: self-holding optical switches 81_1-81_M: junction units 116_1-116_N: limiter amplifier circuits 117: optical switches 119_1-119_N: packet monitors 120_1-120_M: Delay control unit 121: Optical switch monitoring control unit 122: Optical amplifier 123: Collision detection destination control unit 124: Optical circulator 125: 3 dB coupler 126: Non-linear optical fiber 141: Input port 142: Packet multiplexing generation circuit 143: Transmission path coding Unit 144: Transmission path decoding unit 145: Packet reception separation circuit 146: Output port 171: Phase change material

Claims (16)

A photoelectric conversion unit that photoelectrically converts a header of an IP (Internet Protocol) packet;
A header processing unit for obtaining header information of the IP packet using an output signal of the photoelectric conversion unit;
A destination control unit that determines an output route according to a destination included in the header information acquired by the header processing unit;
A payload output unit that outputs the payload of the IP packet to a path determined by the destination control unit as an optical signal;
A header optical signal generation unit that converts the header information acquired by the header processing unit into an optical signal;
An IP packet output unit that outputs a header from the header optical signal generation unit and a payload from the payload output unit to an output path;
An optical transmission device comprising:   An optical signal having an optical signal level in the header of the IP packet is removed, and an optical signal having an optical signal level that is greater than the optical signal level in the header of the IP packet and smaller than the optical signal level in the payload of the IP packet. The optical transmission device according to claim 1, further comprising a payload extraction unit to be passed before the payload output unit or between the payload output unit and the IP packet output unit.   The optical transmission apparatus according to claim 1, wherein the IP packet has a header bit rate lower than a payload bit rate. An optical branching unit for branching the IP packet;
A clock monitor for detecting a clock frequency of one optical signal from the optical branching unit;
According to the clock frequency detected by the clock monitor, the other optical signal from the optical branching unit, an input switching unit that outputs to the photoelectric conversion unit or the payload output unit,
The optical transmission device according to claim 3, further comprising: The IP packet is output to one input port of a 3 dB coupler whose output port is connected to both ends of the nonlinear optical fiber, and an optical signal from the one input port of the 3 dB coupler is output to the payload output unit. An optical circulator,
The one input port is connected to the optical circulator, the other input port is connected to the photoelectric conversion unit, two output ports are connected to both ends of the nonlinear optical fiber, and input to the one input port An optical signal is input to both ends of the nonlinear optical fiber, and the optical signal that has circulated around the nonlinear optical fiber and returned to the two output ports is multiplexed to the one input port and the other input port. An output 3 dB coupler;
A non-linear optical fiber having both ends connected to the output port of the 3 dB coupler;
The optical transmission device according to claim 1.   The IP packet has a pulse duty ratio, an optical pulse peak power, and a time slot of the optical signal in the header of the IP packet, rather than the product of the pulse duty ratio, the optical pulse peak power, and the time slot in the payload of the IP packet. 6. The optical transmission device according to claim 1, wherein the product is smaller.   The optical transmission device according to claim 1, wherein the payload output unit is a self-holding optical switch that maintains a connection state without power consumption while the payload is passing.   8. The light according to claim 7, wherein the self-holding optical switch performs switching by switching between transmission and reflection in the phase change material by using a refractive index change accompanying a temperature change of the phase change material. Transmission equipment. A destination control step of photoelectrically converting the header of the IP packet to obtain header information of the IP packet, and determining an output route according to a destination included in the obtained header information;
A payload output step for outputting the payload of the IP packet to the route determined in the destination control step;
IP packet output step for converting the header information acquired in the destination control step into an optical signal, and outputting the converted header and the payload output in the payload output step to an output route;
An optical transmission method comprising:   In the destination control step, an optical signal having an optical signal level of the header of the IP packet is removed, and an optical signal that is larger than the optical signal level of the header of the IP packet and smaller than the optical signal level of the payload of the IP packet The optical transmission method according to claim 9, wherein the payload is extracted by using a limiter amplifier circuit that passes an optical signal having a level.   The optical transmission method according to claim 9, wherein the IP packet has a header bit rate lower than a payload bit rate.   In the destination control step, the IP packet is branched, a clock frequency of one of the branched optical signals is detected, and the other branched optical signal is converted into a header and a payload of the IP packet according to the detected clock frequency. The optical transmission method according to claim 11, wherein the optical transmission method is separated.   In the destination control step, the IP packet is input from both ends of the nonlinear optical fiber, the IP packets after passing through the nonlinear optical fiber are combined with each other, and the combined optical signal is branched. The optical transmission method according to claim 9, wherein the packet is separated into a header and a payload.   The IP packet has a pulse duty ratio, an optical pulse peak power, and a time slot of the optical signal in the header of the IP packet, rather than the product of the pulse duty ratio, the optical pulse peak power, and the time slot in the payload of the IP packet. The optical transmission method according to claim 9, wherein a product is smaller.   The payload output step uses a self-holding optical switch that maintains a connection state without power consumption while the payload is passing, and outputs to the route determined in the destination control step. The optical transmission method according to any one of 9 to 14.   The light according to claim 15, wherein the self-holding optical switch performs switching by switching between transmission and reflection in the phase change material using a refractive index change accompanying a temperature change of the phase change material. Transmission method.

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