System and method for optical communication using powered light

Abstract

To make an optical power supply and bidirectional optical communication possible with a single optical fiber, which alleviates the constraints on the amount of optical power supply.SOLUTION: A system according to the present disclosure includes a multi-core optical fiber that connects multiple devices, transmits communication light using at least one of the plurality of cores provided in the multi-core optical fiber, and transmits power supply light using at least one of the plurality of cores provided in the multi-core optical fiber, and the core that transmits the power supply light and the core that transmits the communication light in the multi-core optical fiber are different, and the multi-core optical fiber transmits the communication light and the power supply light in a single mode or a pseudo-single mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to systems and methods for optical communication using powered light. [Background technology]

[0002] Systems that perform optical communication using power feeding light have been proposed (see, for example, Non-Patent Documents 1 and 2). In the first technique disclosed in Non-Patent Document 1, two optical fibers are used, one of which is used for optical power feeding and the other for optical communication, to perform optical power feeding from a near-end device to a far-end device and bidirectional optical communication between the near-end device and the far-end device. In this method, the two optical fibers are either two existing single-mode optical fibers, or two existing multimode optical fibers, or one existing single-mode optical fiber and one existing multimode optical fiber.

[0003] The second method disclosed in Non-Patent Document 1 uses one existing single-mode optical fiber or one existing multimode optical fiber, and multiplexes power supply light and communication light with different wavelengths to perform optical power supply from a near-end device to a far-end device and bidirectional optical communication between the near-end device and the far-end device.

[0004] The third technique disclosed in Non-Patent Document 2 uses a double-clad optical fiber / few-mode optical fiber, and transmits power supply light in the higher-order mode / multimode region and communication light in the fundamental mode / single mode region, thereby enabling optical power supply from a near-end device to a far-end device and bidirectional optical communication between the near-end device and the far-end device. Here, the double-clad optical fiber is an optical fiber in which regions transmitting higher-order modes and fundamental modes are multiplexed within the optical fiber cross section. The few-mode optical fiber is an optical fiber with a structure that performs multimode transmission in a specific wavelength band and single-mode transmission at wavelengths longer than the specific wavelength band.

[0005] The first method requires two optical fibers, which complicates the system configuration and increases costs. In the second method, in single-mode optical fibers, the amount of optical power fed to the far-end device is limited by an upper limit on the input optical power due to optical nonlinear effects, and in multimode optical fibers, the communication speed and transmission distance are limited by characteristic degradation due to multimode transmission. In the third method, the optical fiber structure becomes complicated, and the feed length and communication wavelength are restricted by the optical fiber structure. In addition, simultaneous bidirectional communication is not possible when the communication wavelength is one wavelength. In the second and third methods, the higher-order mode / multi-mode region suitable for power feeding is generally on the short wavelength side, so the communication wavelength band is degraded by the Raman scattering characteristics due to the feed wave length. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Non-Patent Document 1. D. Wake et al., “Optically powered remote units for radio-over-fiber systems,” J. Lightw. Technol. 26, 2484-2491 (2008). [Non-patent document 2] M. Matsuura et al., “150-W power-over-fiber using double-clad fibers,” J. Lightw. Technol. 38, 401-408 (2020). Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to enable optical power feeding and bidirectional optical communication with relaxed restrictions on the amount of optical power feeding using a single optical fiber. [Means for solving the problem]

[0008] The present disclosure overcomes the input limitation of power feeding light in existing single-core single-mode optical fibers by providing a multi-core optical fiber for optical power feeding, thereby simultaneously realizing optical power feeding from a near-end device to a far-end device and bidirectional optical communication between the near-end device and the far-end device using a single-mode optical fiber, while eliminating the restriction on the amount of optical power feeding due to single-mode optical power feeding and preventing degradation of communication wavelength characteristics due to multiplexing of the feed wave length and communication wavelength.

[0009] The system of the present disclosure includes a multi-core optical fiber connecting multiple devices, and executes the method of the present disclosure. The method of the present disclosure is executed by a system in which multiple devices are connected by a multi-core optical fiber, and transmits communication light using at least one of multiple cores included in the multi-core optical fiber, and transmits feeding light using at least one of multiple cores included in the multi-core optical fiber.

[0010] In the present disclosure, the cores transmitting the power supply light and the cores transmitting the communication light in the multi-core optical fiber are different. The multi-core optical fiber transmits the communication light and the power supply light in a single mode or a quasi-single mode. This enables optical power supply and bidirectional optical communication with a single optical fiber, with the constraints on the optical power supply amount relaxed.

[0011] In addition, the wavelength of the communication light may be shorter than the wavelength of the power supply light. In the present disclosure, by setting the length of the power supply light to be longer than the communication wavelength, it is possible to mitigate the influence of Raman scattering caused by the power supply light.

[0012] The multi-core optical fiber may have two or more cores for transmitting the feed light, thereby making it possible to obtain a larger power in the far-end device.

[0013] The far-end device receiving the power supply light comprises: a photoelectric conversion element that converts light into electricity; a transmitter that transmits communication light using the power output from the photoelectric conversion element; a receiver that receives communication light using the power output from the photoelectric conversion element; The device may also include:

[0014] The system of the present disclosure may employ a configuration in which the multi-core optical fiber has four cores, two of the four cores are used to transmit power supply light, and the remaining two of the four cores are used to transmit communication light having a different transmission direction.

[0015] The system of the present disclosure may employ a configuration in which the multi-core optical fiber has four cores, three of the four cores are used to transmit power supply light, and the remaining core of the four cores is used to transmit communication light having a different transmission direction and wavelength.

[0016] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0017] The present disclosure makes it possible to realize optical power feeding and bidirectional optical communication with a single optical fiber, with the restrictions on the amount of optical power feeding relaxed. [Brief explanation of the drawings]

[0018] [Figure 1] 1 illustrates an example system configuration of the present disclosure. [Figure 2] An example of the optical characteristics of the multi-core optical fiber used in this embodiment is shown below. [Figure 3] The dependence of the input optical power on the number of input cores is shown. [Figure 4] This shows the dependency of power consumption after OE conversion on the number of input cores. [Figure 5] This shows the dependence of the bit error rate in two-way communication on the received light intensity. [Figure 6] 1 illustrates an example system configuration of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0020] (Example 1) 1 shows a configuration diagram of a system according to the present disclosure. The system of this embodiment is a power supply and two-way communication system in which a near-end device 91 and a far-end device 95 are connected by a multi-core optical fiber 93, and the near-end device 91 and the far-end device 95 perform two-way communication. As an example, a power supply and two-way communication system using a multi-core optical fiber 93 in which four cores having optical properties equivalent to those of a normal single-mode optical fiber are arranged in a square lattice pattern in a cladding with a diameter of 125 μm will be described below.

[0021] The power supply and bidirectional communication system of this embodiment transmits communication light using at least one of the multiple cores included in the multi-core optical fiber 93, and transmits power supply light using at least one of the multiple cores included in the multi-core optical fiber 93. For example, in this embodiment, λ1 and λ2 are used as communication wavelengths of the communication light, and λ3 is used as a feed wavelength of the power supply light. Here, in the power supply and bidirectional communication system of the present disclosure, λ1 and λ2 are set to wavelengths shorter than λ3, thereby avoiding the influence of Raman scattering due to λ3.

[0022] For example, a near-end device 91 has a transmitter (Tx) 11 of wavelength λ1, a receiver (Rx) 12 of wavelength λ2, and a feed light source 13 of wavelength λ3. Feed light from the feed light source 13 is branched into two ports, and these are connected to the first to fourth cores of a multi-core optical fiber 93 via a multiplexer / demultiplexer 92 together with the ports for λ1 and λ2. For example, the transmitter 11 is connected to the first core, the receiver 12 is connected to the second core, and the feed light source 13 is connected to the third and fourth cores. As described above, in this embodiment, in the multi-core optical fiber 93, a core that transmits feed light and a core that transmits communication light are different, and communication light with different transmission directions and wavelengths is transmitted using two cores.

[0023] Here, the multiplexing / demultiplexing device 92 can use any means capable of coupling the four light beams from the near-end device 91 to different cores, such as a WDM coupler, a power coupler, a Fan-In / Fan-Out (FIFO) device, etc. The multiplexing / demultiplexing device 94 can also use any means capable of separating each core provided in the multi-core optical fiber 93, and the same means as the multiplexing / demultiplexing device 92 can be used.

[0024] The far-end device 95 has a receiver 51 of wavelength λ1, a transmitter 52 of wavelength λ2, and an optical-electrical (OE) conversion element 53 of wavelength λ3. Each device / element is connected to the first to fourth cores of the multi-core optical fiber 93. For example, the receiver 51 is connected to the first core, the transmitter 52 is connected to the second core, and the OE conversion element 53 is connected to the third and fourth cores.

[0025] Furthermore, the power converted from OE by the far-end device 95 is supplied via an appropriate electric circuit as power to the receiver 51 and the transmitter 52. With this configuration, even if the far-end device 95 is in a power-off state, it can perform two-way communication by receiving power from the near-end device 91.

[0026] 2 shows an example of the optical characteristics of the multi-core optical fiber 93 used in this embodiment. In this embodiment, the cutoff wavelength is less than 1260 nm, the mode field diameter (MFD) is 8.6 μm, the bending loss is less than 0.1 dB, the zero-dispersion wavelength is 1300 to 1320 nm, and the crosstalk (XT) is less than −47 dB / km. Here, the MFD is shown as a value at 1310 nm, and the bending loss and crosstalk are shown as values ​​at a wavelength of 1625 nm. The bending loss is also shown as a value after 100 turns with a bending radius of 30 mm. The transmission characteristics of each core of the multi-core optical fiber 93 can be set to any optical characteristics as long as it can realize single-mode or quasi-single-mode transmission. However, since existing general-purpose transceivers can be used, it is desirable for the optical characteristics to be equivalent to those of a general-purpose single-mode optical fiber (e.g., an optical fiber conforming to ITU-T Recommendation G.652).

[0027] In the multi-core optical fiber 93 used in the first embodiment of the present disclosure, all cores satisfy the optical characteristics conforming to ITU-T Recommendation G.652 and operate in a single mode at wavelengths of 1260 nm or longer. Although existing optical fiber standards do not specify crosstalk, good transmission characteristics can be obtained if crosstalk characteristics of approximately -20 dB or less are obtained at the receiving end at the wavelength used. The multi-core optical fiber 93 of this embodiment can achieve crosstalk characteristics of less than -40 dB at wavelengths of 1625 nm or shorter even after propagation over approximately 2.6 km.

[0028] 3 and 4 show the dependence of the input feed optical power and the power after OE conversion on the number of input cores. The input feed optical power is the total feed optical power output from the feed light source 13 and input to the cores of the multi-core optical fiber 93. The power after OE conversion is the power after OE conversion in the far-end device 95. In this embodiment, the feed wave length is set to 1550 nm, and the transmission distance from the near-end device 91 to the far-end device 95 is set to 2.6 km.

[0029] 3 and 4, it can be seen that by distributing the optical feed light among multiple cores and propagating it, a larger optical feed light and OE conversion voltage can be obtained at the far-end device 95, which is the receiving end, than when a single core is used. The drive power of the receiver 51 and transmitter 52 used in this embodiment is 600 mW, and by distributing the optical feed light among two cores, it is possible to optically feed enough power to drive the receiver 51 and transmitter 52 at the far end.

[0030] Figure 5 shows the dependence of the bit error rate (BER) of two-way communication on the intensity of the received light. Here, the transmitter 11 and receiver 12 were driven by the commercial power supply of the near-end device 91, and the receiver 51 and transmitter 52 on the far-end device 95 side were driven by power obtained from the optical power supply. The transmitted light was an intensity-modulated signal of 1.25 Gbit / s, and the PRBS (Pseudo-Random Binary Sequence) was 2. 15 In this embodiment, λ1 and λ2 were both set to 1310 nm.

[0031] In the figure, square indicates the BER (Bit Error Rate) of the signal transmitted from transmitter 11 provided in near-end device 91 and received by receiver 51 provided in far-end device 95, and black circles indicate the BER of the signal transmitted from transmitter 52 provided in far-end device 95 and received by receiver 12 provided in near-end device 91. It can be seen that good transmission characteristics are achieved even when power supply light is used.

[0032] (Example 2) 6 shows a configuration diagram of a power supply and two-way communication system according to a second embodiment of the present disclosure. In the power supply and two-way communication system of this embodiment, the configurations of a near-end device 91 and a far-end device 95 and the characteristics of a multi-core optical fiber 93 are the same as those of the first embodiment. However, the transmitter 11 and the receiver 12 are connected to the first core, and the power supply light source 13 is connected to the second, third, and fourth cores.

[0033] The power supply light from the power supply light source 13 is branched into three ports and is input to the second to fourth cores of the multi-core optical fiber 93, and the signal light propagating through the first core is connected to the transmitter 52 or the receiver 51, or to both the receiver 51 and the transmitter 52, via a WDM coupler or the like.

[0034] Here, the communication wavelength of the transmitter 11 and the receiver 51 is λ1, 52 The communication wavelength of the receiver 12 is λ2, and the feed wave length is λ3. In this embodiment, in the multi-core optical fiber 93, a core for transmitting the feed light and a core for transmitting the communication light are different, and one core is used to transmit the communication light with different transmission directions and wavelengths.

[0035] For example, if λ1 is 1310 nm, λ2 is 1550 nm, and λ3 is 1560 nm, the Raman spectrum generated in the feed wave length will be approximately 100 nm longer, increasing the crosstalk component between adjacent cores at that wavelength. However, since λ1 and λ2 are set to shorter wavelengths than λ3, there is no effect of crosstalk noise.

[0036] On the other hand, if λ3 is set to a wavelength shorter than λ2 (for example, 1450 nm) or shorter than λ1 (for example, 1160 nm), the Raman spectrum components of the feed wavelength will cause crosstalk noise to degrade the λ2 signal light when λ3 is 1450 nm, and the λ1 signal light when λ3 is 1160 nm.

[0037] Therefore, in the second embodiment, by setting λ1<λ2<λ3, suitable two-way communication can be realized.

[0038] Although the above-described multi-core optical fiber 93 has four cores arranged in a square lattice pattern in a cladding with a diameter of 125 μm, the cladding diameter of the multi-core optical fiber 93, the number of cores provided in the cladding, and the arrangement thereof are arbitrary. For example, the multi-core optical fiber 93 may have five or more cores, such as eight cores.

[0039] Although an example in which the feed wave length is only λ3 has been shown, two or more feed wave lengths may be used. In this case, the effect of the present disclosure can be obtained by making all feed wave lengths longer than all communications wavelengths. [Explanation of symbols]

[0040] 11, 52: Transmitter 12, 51: Receiver 13: Power supply light source 53: Photoelectric (OE) conversion element 91: Near-end device 92, 94: Multiplexing / demultiplexing device 93: Multi-core optical fiber 95: Far end device

Claims

1. A multi-core optical fiber is provided to connect a plurality of devices, transmitting communication light using at least one of a plurality of cores provided in the multi-core optical fiber; transmitting a feed light beam using at least one of a plurality of cores provided in the multi-core optical fiber; a core transmitting the feeding light and a core transmitting the communication light in the multi-core optical fiber are different from each other; where λ1 is a communication wavelength of the communication light transmitted in the same direction as the transmission direction of the power supply light, λ2 is a communication wavelength of the communication light transmitted in the opposite direction to the transmission direction of the power supply light, and λ3 is a feed wave length of the power supply light, λ1<λ2<λ3 holds true, the multi-core optical fiber transmits the communication light and the power supply light in a single mode or a quasi-single mode; system.

2. The multi-core optical fiber is characterized in that the feed light is transmitted using two or more cores provided in the multi-core optical fiber. The system of claim 1 .

3. The far-end device receiving the power supply light comprises: a photoelectric conversion element that converts light into electricity; a transmitter that transmits the communication light having a communication wavelength of λ2 using the power output from the photoelectric conversion element; a receiver that receives the communication light having a communication wavelength of λ1 using the power output from the photoelectric conversion element; characterized in that it comprises The system of claim 1 .

4. the multi-core optical fiber has four cores, transmitting the power supply light using two of the four cores; the remaining two cores of the four cores are used to transmit the communication light in different transmission directions, The system of claim 1 .

5. the multi-core optical fiber has four cores, transmitting the power supply light using three of the four cores; the remaining one core of the four cores is used to transmit the communication light having a different transmission direction and wavelength, The system of claim 1 .

6. A method performed by a system in which a plurality of devices are connected by a multi-core optical fiber, comprising: transmitting communication light using at least one of a plurality of cores provided in the multi-core optical fiber; transmitting a feed light beam using at least one of a plurality of cores provided in the multi-core optical fiber; a core transmitting the feeding light and a core transmitting the communication light in the multi-core optical fiber are different from each other; where λ1 is a communication wavelength of the communication light transmitted in the same direction as the transmission direction of the power supply light, λ2 is a communication wavelength of the communication light transmitted in the opposite direction to the transmission direction of the power supply light, and λ3 is a feed wave length of the power supply light, λ1<λ2<λ3 holds true, the multi-core optical fiber transmits the communication light and the power supply light in a single mode or a quasi-single mode; method.

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