Patent Publication Number: US-2022236487-A1

Title: Optical fiber component, demultiplexer, and optical transmission system

Description:
TECHNICAL FIELD 
     The present disclosure relates to an optical fiber component, a demultiplexer and an optical transmission system. 
     BACKGROUND ART 
     There is disclosed in Patent Literature 1 an optical multiplexer/demultiplexer that separates (demultiplexes) light of a plurality of wavelengths transmitted through an optical fiber. In the optical multiplexer/demultiplexer of Patent Literature 1, in the middle of an optical path, an optical filter allows light of a first wavelength and light of a second wavelength to pass through and reflects light of a third wavelength, thereby transmitting light of a plurality of wavelengths to a plurality of cores. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2013-225010 A 
     SUMMARY OF INVENTION 
     Problem to Solve 
     In the case where light of a plurality of wavelengths is transmitted through a single optical fiber, it is desired that the light of a plurality of wavelengths can be demultiplexed efficiently at the output end of the optical fiber. 
     Solution to Problem 
     An optical fiber component of the present disclosure is an optical fiber component including a plurality of optical fibers bundled together at one end at least, the plurality of optical fibers including: 
     a first optical fiber centered at the one end; and 
     a plurality of second optical fibers disposed around the first optical fiber at the one end, 
     wherein each of the plurality of second optical fibers has, at the one end, an end face shape including a straight portion and a corner portion. 
     A demultiplexer of the present disclosure is a demultiplexer including the above optical fiber component, 
     wherein the demultiplexer demultiplexes light of a plurality of wavelengths output from an optical fiber including a core, a first cladding located around the core, and a second cladding located around the first cladding, and 
     wherein the one end of the optical fiber component faces an output end face of the optical fiber. 
     An optical transmission system of the present disclosure is an optical transmission system including the above demultiplexer, 
     wherein the optical transmission system transmits signal light and feed light through the optical fiber, and 
     wherein the demultiplexer faces the output end face of the optical fiber. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a power over fiber system of an embodiment(s). 
         FIG. 2  is a perspective view of a demultiplexer shown in  FIG. 1 . 
         FIG. 3  is a front view of a fiber array shown in  FIG. 2 . 
         FIG. 4  is an illustration to explain configuration of the fiber array shown in  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments of the present disclosure will be described in detail with reference to the drawings.  FIG. 1  is a block diagram of a power over fiber system of an embodiment(s). 
     As shown in  FIG. 1 , a power over fiber (PoF) system  1  of this embodiment is an optical transmission system that performs power supply and optical communication through an optical fiber  250 . The power over fiber system  1  includes: a first data communication device  100  including a power sourcing equipment (PSE)  110 ; an optical fiber cable  200 ; and a second data communication device  300  including a powered device (PD)  310 . The power over fiber system  1  further includes a demultiplexer  360 . The demultiplexer  360  may be included in the second data communication device  300 . 
     The power sourcing equipment  110  includes a semiconductor laser  111  for power supply. The first data communication device  100  includes, in addition to the power sourcing equipment  110 , a transmitter  120  and a receiver  130  for data communication. The first data communication device  100  corresponds to a data terminal equipment (DTE), a repeater or the like. The transmitter  120  includes a semiconductor laser  121  for signals and a modulator  122 . The receiver  130  includes a photodiode  131  for signals. 
     The optical fiber cable  200  includes the optical fiber  250 . The optical fiber  250  includes: a core  210  that forms a transmission path of signal light; a cladding  220  (corresponding to a first cladding) that is arranged around the core  210  and forms a transmission path of feed light; and an outer cladding  225  (corresponding to a second cladding) that is arranged around the cladding  220 . 
     The powered device  310  includes a photoelectric conversion element  311 . The second data communication device  300  includes, in addition to the powered device  310 , a transmitter  320 , a receiver  330  and a data processing unit  340 . The second data communication device  300  corresponds to a power end station or the like. The transmitter  320  includes a semiconductor laser  321  for signals and a modulator  322 . The receiver  330  includes a photodiode  331  for signals. The data processing unit  340  processes received signals. The second data communication device  300  is a node in a communication network. The second data communication device  300  may be a node that communicates with another node. 
     The first data communication device  100  is connected to a power source, and electrically drives the semiconductor laser  111 , the semiconductor laser  121 , the modulator  122 , the photodiode  131  and so forth. The first data communication device  100  is a node in a communication network. The first data communication device  100  may be a node that communicates with another node. 
     The semiconductor laser  111  oscillates with the electric power from the power source, thereby outputting feed light  112 . 
     The photoelectric conversion element  311  converts the feed light  112  transmitted through the optical fiber cable  200  into electric power. The electric power obtained by the conversion of the feed light  112  by the photoelectric conversion element  311  is driving power needed in the second data communication device  300 , for example, driving power for the transmitter  320 , the receiver  330  and the data processing unit  340 . The second data communication device  300  may be capable of outputting, for an external device(s), the electric power obtained by the conversion of the feed light  112  by the photoelectric conversion element  311 . 
     Semiconductor materials of semiconductor regions of the semiconductor laser  111  and the photoelectric conversion element  311  are semiconductors having a laser wavelength being a short wavelength of 500 nm or less. The semiconductor regions exhibit light-electricity conversion effect. Semiconductors having a laser wavelength being a short wavelength have a large band gap and a high photoelectric conversion efficiency, and hence improve photoelectric conversion efficiency at the power supplying side and the power receiving side in optical power supply, and improve optical power supply efficiency. 
     Hence, as the semiconductor materials, laser media having a laser wavelength (base wave) of 200 nm to 500 nm may be used. Examples thereof include diamond, gallium oxide, aluminum nitride and gallium nitride. Further, as the semiconductor materials, semiconductors having a band gap of 2.4 eV or greater are used. For example, laser media having a band gap of 2.4 eV to 6.2 eV may be used. Examples thereof include diamond, gallium oxide, aluminum nitride and gallium nitride. 
     Laser light having a longer wavelength tends to have a higher transmission efficiency, whereas laser light having a shorter wavelength tends to have a higher photoelectric conversion efficiency. Hence, when laser light is transmitted for a long distance, laser media having a laser wavelength (base wave) of greater than 500 nm may be used as the semiconductor materials, whereas when the photoelectric conversion efficiency is given priority, laser media having a laser wavelength (base wave) of less than 200 nm may be used as the semiconductor materials. 
     Any of these semiconductor materials may be used in one of the semiconductor laser  111  and the photoelectric conversion element  311 . This improves the photoelectric conversion efficiency at either the power supplying side or the power receiving side, and improves the optical power supply efficiency. 
     The modulator  122  of the transmitter  120  modulates laser light  123  output by the semiconductor laser  121  to signal light  125  on the basis of transmission data  124 , and outputs the signal light  125 . 
     The photodiode  331  of the receiver  330  demodulates the signal light  125  transmitted through the optical fiber cable  200  to an electric signal, and outputs the electric signal to the data processing unit  340 . The data processing unit  340  transmits data of the electric signal to a node, and also receives data from the node and outputs the data to the modulator  322  as transmission data  324 . 
     The modulator  322  of the transmitter  320  modulates laser light  323  output by the semiconductor laser  321  to signal light  325  on the basis of the transmission data  324 , and outputs the signal light  325 . 
     The photodiode  131  of the receiver  130  demodulates the signal light  325  transmitted through the optical fiber cable  200  to an electric signal, and outputs the electric signal. Data of the electric signal is transmitted to a node, whereas data from the node is the transmission data  124 . 
     The feed light  112  and the signal light  125  from the first data communication device  100  are input to one end  201  of the optical fiber cable  200 , propagate through the cladding  220  and the core  210 , respectively, and are output from the other end  202  of the optical fiber cable  200  to the second data communication device  300 . 
     The signal light  325  from the second data communication device  300  is input to the other end  202  of the optical fiber cable  200 , propagates through the core  210 , and is output from the one end  201  of the optical fiber cable  200  to the first data communication device  100 . 
     &lt;Demultiplexer&gt; 
       FIG. 2  is a perspective view of the demultiplexer shown in  FIG. 1 .  FIG. 3  is a front view of an optical fiber component shown in  FIG. 2 .  FIG. 4  is an illustration to explain configuration of the optical fiber component shown in  FIG. 2 . 
     As shown in  FIG. 2 , the demultiplexer  360  includes an optical fiber component  360 A and an optical fiber array  360 B. 
     The optical fiber component  360 A is configured such that optical fibers  362 ,  363   a - 363   f  adhere to one another with (via) filler  364   a  and coating  364   b , such as curable resin composites. The optical fibers  362 ,  363   a - 363   f  are each a strand having a core and a cladding, for example. The optical fiber  362  (corresponding to a first optical fiber) is centered at the input end. The other optical fibers  363   a - 363   f  (corresponding to second optical fibers) are disposed around (i.e., so as to surround) the central optical fiber  362 . The central optical fiber  362  has a core diameter (core width) that allows the wavelength of the signal light to pass through. The surrounding optical fibers  363   a - 363   f  each have a core diameter (core width) that allows the wavelength of the feed light to pass through. 
     The central optical fiber  362  has a cross-sectional area corresponding to the core  210  of the optical fiber  250 , and is disposed at a position corresponding to the core  210  of the optical fiber  250 . The position corresponding to the core  210  means a position that faces the output end face of the core  210  and to which the signal light  125  is input from the core  210 . 
     The surrounding optical fibers  363   a - 363   f  lie annularly at the input end, and are disposed at positions corresponding to the cladding  220  of the optical fiber  250 . The positions corresponding to the cladding  220  mean positions that face the output end face of the cladding  220  and to which the feed light  112  is input from the cladding  220 . At the input end, the width from the inner peripheral end to the outer peripheral end of the surrounding optical fibers  363   a - 363   f  viewed as an annular assembly may be equal to or larger than the width from the inner peripheral end to the outer peripheral end of the cladding  220 . 
     The input end face of each of the surrounding optical fibers  363   a - 363   f  is, for example, in the shape of a polygon, such as a regular hexagon, having straight portions P 1  and corner portions P 2  (shown in  FIG. 3 ). At the input end, the straight portions P 1  of each two adjacent optical fibers of the surrounding optical fibers  363   a - 363   f  may be in contact with one another, and also the corner portions P 2  thereof may be in contact with one another. The input end face of each of the optical fibers  363   a - 363   f  may be in the shape of being surrounded by a straight portion(s), corner portions and a curved portion(s). 
     The input end face of the central optical fiber  362  is, for example, in the shape of a polygon, such as a regular hexagon, but may be circular. At the input end shown in  FIG. 2  to  FIG. 4 , between the central optical fiber  362  and the surrounding optical fibers  363   a - 363   f , the filler  364   a  is interposed. However, at the input end, the central optical fiber  362  and the surrounding optical fibers  363   a - 363   f  may be in contact with one another with no gap. 
     As shown in  FIG. 4 , the optical fibers  362 ,  363   a - 363   f  each have a tapered portion TP the cross-sectional area of which decreases from a side close to the input end toward a side far from the input end. At the output end of the optical fiber component  360 A, the optical fibers  362 ,  363   a - 363   f  are separate from one another. The output end face of each of the optical fibers  362 ,  363   a - 363   f  may be circular. Only the surrounding optical fibers  363   a - 363   f  may have the tapered portions TP described above. 
     As shown in  FIG. 2  and  FIG. 4 , the optical fiber array  360 B includes an optical fiber  366  through which the signal light  125  propagates, a plurality of optical fibers  367   a - 367   f  through which the feed light  112  propagates, and a holder  368  that holds one end of the optical fibers  366 ,  367   a - 367   f . In  FIG. 4 , of the optical fibers  367   a - 367   f , only the optical fibers  367   c ,  367   f  are shown, but the optical fibers  367   a - 367   f  are disposed at positions corresponding to the optical fibers  363   a - 363   f.    
     The optical fibers  366 ,  367   a - 367   f  are each an optical fiber that includes a core and a cladding and the section of which is circular. The optical fiber  366  has a core diameter that allows the signal light  125  to propagate through. The optical fibers  367   a - 367   f  each have a core diameter that allows the feed light  112  to propagate through. 
     The holder  368  holds the optical fibers  366 ,  367   a - 367   f  at the input end. By being held by the holder  368 , one optical fiber,  366 , is centered, and the other optical fibers,  367   a - 367   f , are disposed around the optical fiber  366 , at the input end. In a state in which the optical fiber array  360 B and the optical fiber component  360 A are combined, the input end faces of the optical fibers  366 ,  367   a - 367   f  face the output end faces of the optical fibers  362 ,  363   a - 363   f  of the optical fiber component  360 A, respectively. 
     The output end of the optical fibers  366 ,  367   a - 367   f  is free from the holder  368 . The optical fiber  366 , which is centered at the input end, has its output end in front of the photodiode  331 . The optical fibers  367   a - 367   f , which are disposed around the optical fiber  366  at the input end, have their output ends in front of the photoelectric conversion element  311 . 
     &lt;Actions and Effects of Demultiplexer&gt; 
     The feed light  112  and the signal light  125  input from the first data communication device  100  have wavelengths different from one another and propagate through the cladding  220  and the core  210  of the optical fiber  250 , respectively. The signal light  125  output from the core  210  of the optical fiber  250  at the other end  202  propagates through the central optical fiber  362  of the optical fiber component  360 A and the central optical fiber  366  of the optical fiber array  360 B to be transmitted to the photodiode  331 . The feed light  112  output from the cladding  220  is transmitted to the surrounding optical fibers  363   a - 363   f  of the optical fiber component  360 A. 
     At the input end of the optical fiber component  360 A, of the optical fibers  363   a - 363   f  to which the feed light  112  is input, the straight portions P 1  of each two optical fibers adjacent in the circumferential direction are in contact with one another, so that the amount of gaps between the optical fibers  363   a - 363   f  is small. Further, at the abovementioned input end, the width from the inner peripheral end to the outer peripheral end of the optical fibers  363   a - 363   f , to which the feed light  112  is input, viewed as an annular assembly is sufficiently large. Hence, the feed light  112  output from the cladding  220  of the optical fiber  250  is transmitted to the optical fibers  363   a - 363   f  of the optical fiber component  360 A with little leakage. 
     Further, the feed light  112  propagating through the optical fibers  363   a - 363   f  is narrowed by the tapered portions TP of the optical fibers  363   a - 363   f , and is transmitted to the optical fibers  367   a - 367   f  of the optical fiber array  360 B with little leakage. Then, the feed light  112  propagates through the optical fibers  367   a - 367   f , and is transmitted to the photoelectric conversion element  311 . Hence, the feed light  112  not reaching the photoelectric conversion element  311  accounts for a small proportion of the feed light  112  output from the cladding  220 . Thus, highly efficient demultiplexing is achieved. 
     The signal light  325  output from the second data communication device  300  is input to the optical fiber  366 , which is held at the center of the optical fiber array  360 B, via a not-shown multiplexer. Then, the signal light  325  is transmitted to the core  210  of the optical fiber  250  via the central optical fiber  362  of the optical fiber component  360 A. 
     As described above, according to the optical fiber component  360 A of this embodiment, the optical fiber component  360 A includes the optical fiber  362  disposed at the center and the optical fibers  363   a - 363   f  disposed around the optical fiber  362 . Further, each of the optical fibers  363   a - 363   f  has, at one end (e.g., input end), an end face shape having the straight portions P 1  and the corner portions P 2 . These end faces of the optical fibers  363   a - 363   f  lying annularly can reduce the amount of gaps therebetween as compared with a case where the end faces are circular. Thus, one end of the optical fiber component  360 A facing the cladding  220  of the optical fiber  250  allows laser light output from the cladding  220  to be taken into the optical fibers  363   a - 363   f  with little loss. 
     Further, according to the optical fiber component  360 A of this embodiment, at one end (e.g., input end), the straight portions P 1  of each two adjacent optical fibers of the surrounding optical fibers  363   a - 363   f  are in contact with one another. This configuration can further reduce the amount of gaps between the optical fibers  363   a - 363   f , and allows laser light output from the cladding  220  to be taken into the optical fibers  363   a - 363   f  with less loss. 
     Further, according to the optical fiber component  360 A of this embodiment, each of the surrounding optical fibers  363   a - 363   f  has the tapered portion TP, the cross-sectional area of which decreases from one end (input end) toward the other end (output end). This makes it possible to, at the other end, separate the optical fibers  363   a - 363   f  from one another and transmit the feed light  112  to the optical fiber array  360 B with little loss. 
     According to the demultiplexer  360  of this embodiment, thanks to the above-described actions of the optical fiber component  360 A, the demultiplexer  360  can demultiplex laser light of a plurality of wavelengths transmitted through the optical fiber  250 , which is a double-clad fiber, with a high efficiency. 
     According to the power over fiber system  1  of this embodiment, the power over fiver system  1  including the demultiplexer  360 , which provides the above-described effects, can achieve highly efficient transmission of the signal light  125  and the feed light  112 . 
     Although one or more embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiment(s), the optical fiber component is configured such that the optical fibers are bundled together from one end to the other end. However, the optical fiber component may be configured such that the optical fibers are bundled together at one end and not bundled together at the other end. For example, the optical fiber component  360 A and the optical fiber array  360 B may be integrated. Further, in the above embodiment(s), the surrounding optical fibers  363   a - 363   f  of the optical fiber component  360 A lie annularly in the circumferential direction. However, optical fibers surrounding the central one may lie not only annularly in the circumferential direction but also at multiple stages in the radial direction. In this case, of the surrounding optical fibers, the straight portions of each two adjacent optical fibers in the radial direction may also be in contact with one another. This configuration can further reduce the amount of gaps between the surrounding optical fibers. 
     Further, in the above embodiment(s), the straight portions P 1  of the surrounding optical fibers  363   a - 363   f  of the optical fiber component  360 A are in contact with one another at one end (input end). However, the straight portions P 1  thereof may not be in contact with one another as far as they are close to one another. This can reduce the amount of gaps between the optical fibers as compared with the case where optical fibers each having a circular end face are ranged. 
     Further, in the above embodiment(s), the optical fibers of the optical fiber component have the tapered portions TP. However, if the optical fibers are free at the other end, the tapered portions TP may be omitted. Even when the optical fibers are bundled together at the other end, the tapered portions TP may be omitted by adopting a structure in which at the other end, the optical fibers are fixed with spaces therebetween widened. The details described in the embodiment(s) can be appropriately modified within a range not departing from the scope of the invention. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable to an optical fiber component, a demultiplexer and an optical transmission system. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Power over Fiber System (Optical Transmission System) 
               100  First Data Communication Device 
               110  Power Sourcing Equipment 
               111  Semiconductor Laser for Power Supply 
               112  Feed Light 
               120  Transmitter 
               121  Semiconductor Laser for Signals 
               122  Modulator 
               123  Laser Light 
               124  Transmission Data 
               125  Signal Light 
               130  Receiver 
               131  Photodiode for Signals 
               200  Optical Fiber Cable 
               201  One End of Optical Fiber Cable 
               202  Other End of Optical Fiber Cable 
               210  Core 
               220  Cladding (First Cladding) 
               225  Outer Cladding (Second Cladding) 
               250  Optical Fiber 
               300  Second Data Communication Device 
               310  Powered Device 
               311  Photoelectric Conversion Element 
               320  Transmitter 
               321  Semiconductor Laser for Signals 
               322  Modulator 
               323  Laser Light 
               324  Transmission Data 
               325  Signal Light 
               330  Receiver 
               331  Photodiode for Signals 
               340  Data Processing Unit 
               360  Demultiplexer 
               360 A Optical Fiber Component 
               360 B Optical Fiber Array 
               362  Optical Fiber (First Optical Fiber) 
               363   a  to  363   f  Optical Fiber (Second Optical Fiber) 
             TP Tapered Portion 
               366 ,  367   a  to  367   f  Optical Fiber 
               368  Holder 
             P 1  Straight Portion 
             P 2  Corner Portion