WO2021059618A1 - Fibre à bande interdite photonique et dispositif laser - Google Patents

Fibre à bande interdite photonique et dispositif laser Download PDF

Info

Publication number
WO2021059618A1
WO2021059618A1 PCT/JP2020/023217 JP2020023217W WO2021059618A1 WO 2021059618 A1 WO2021059618 A1 WO 2021059618A1 JP 2020023217 W JP2020023217 W JP 2020023217W WO 2021059618 A1 WO2021059618 A1 WO 2021059618A1
Authority
WO
WIPO (PCT)
Prior art keywords
shape
predetermined
collective structure
band gap
collective
Prior art date
Application number
PCT/JP2020/023217
Other languages
English (en)
Japanese (ja)
Inventor
紀子 亘
暁巳 ▲高▼野
あゆみ 内藤
渡辺　俊哉
藤谷　泰之
Original Assignee
三菱重工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 三菱重工業株式会社 filed Critical 三菱重工業株式会社
Priority to JP2021548340A priority Critical patent/JP7135220B2/ja
Publication of WO2021059618A1 publication Critical patent/WO2021059618A1/fr

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/032—Optical fibres with cladding with or without a coating with non solid core or cladding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers

Definitions

  • the present disclosure relates to a photonic band gap fiber and a laser device.
  • TIR total internal reflection
  • PBG photonic Band Gap
  • PCF refractive index waveguide photonic crystal type
  • a single-mode optical fiber that supports high power is required.
  • the light is dispersed in the conventional optical fiber configuration, resulting in a multi-mode.
  • the present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a photonic band gap fiber and a laser device capable of suppressing mode dispersion at high output.
  • the first aspect of the present disclosure is a unit structure portion provided around the core portion through which light propagates and having a refractive index different from that of the background material in a cross section orthogonal to the longitudinal direction of the core portion.
  • a plurality of collective structure portions having a predetermined shape formed by arranging a plurality of the collective structure portions are arranged so as to have fractal properties, and a predetermined side in a shape connecting the centers of the collective structure portion and the collective structure included in the shape.
  • the predetermined side of the portion in the predetermined shape is a photonic bandgap fiber including a clad portion having a predetermined angle larger than 0 °.
  • the photonic band gap fiber 1 according to the present disclosure can be applied to, for example, a machine tool using a high-power laser, a high-power energy transmission, a laser device such as a laser transmitter, and the like.
  • the photonic band gap fiber 1 is not limited to the above, and can be applied to a wide range of fields as an optical fiber that suppresses mode dispersion (more preferably, single mode transmission) at high output.
  • the high output is, for example, an output of 10 kW or more.
  • the high output includes, for example, one of 1 kW or more in the case of a continuous oscillation laser or a pulse laser. In the case of a pulse laser, since the pulse energy / pulse time width is the peak output, the peak output may be as high as 200 MW or 20 GW, but these are also included in the high output.
  • FIG. 1 is a cross-sectional view of the photonic band gap fiber 1 according to the first embodiment of the present disclosure.
  • the cross section is a plane orthogonal to the longitudinal direction of the core portion 2 through which light is transmitted.
  • the photonic band gap fiber 1 according to the present embodiment includes a core portion (core region) 2 and a clad portion (clad region) 3 as main configurations. That is, the photonic band gap fiber 1 has the configuration shown in FIG. 1 in any cross section.
  • the background material for example, a quartz glass-based material is used.
  • the core portion 2 is a region in which light propagates in the photonic band gap fiber 1 which is an optical fiber.
  • the core portion 2 is provided at the central portion in the cross section of the photonic band gap fiber 1, and is continuously provided from the input end to the output end. That is, light is input to the core portion 2 at the input end of the photonic band gap fiber 1, the light propagates through the core portion 2, and is output from the output end.
  • the clad portion 3 is configured by applying the fractal structure, mode dispersion is suppressed in the propagating light.
  • the core portion 2 is shown as an example in a hexagon, but since the core portion 2 is a region where light propagates in the photonic band gap fiber 1, it is not limited to a hexagon, but has a circular shape or the like. It may have other shapes.
  • the core portion 2 is configured by using pores, a material equal to the background material, a material having a refractive index different from that of the background material, or an aggregate structure portion 4 described later.
  • a hole is a hole (gas such as air or vacuum).
  • the material equivalent to the background material is a quartz glass-based material when the core portion 2 is not particularly processed and, for example, a quartz glass-based material is used as the background material.
  • the material having a different refractive index from the background material is a material having a higher or lower refractive index than the material used as the background material, and for example, boron-added glass or fluoridated glass is used.
  • the collective structure portion 4 has the same structure as the collective structure portion 4 formed of the clad portion 3, and a plurality of unit structure portions 5 having different refractive indexes with respect to the background material are arranged. It becomes the collective structure part 4 of the predetermined shape S formed by.
  • FIG. 1 shows an example in which the core portion 2 is made of a material equal to the background material.
  • the core portion 2 is configured to have the same shape as the collective structure portion 4 (that is, a hexagon) of the clad portion 3 as shown in FIG. It may be a circular shape or another shape such as a circular shape.
  • the size of the core portion 2 (for example, hexagonal area, circular area, diameter, etc.) is designed based on the intensity (output) of propagating light. That is, the size of the core portion 2 is set based on the required output performance.
  • the core diameter is, for example, about 60 ⁇ m.
  • the wavelength of a general fiber laser is 1.07 ⁇ m, and mode dispersion occurs when the core diameter and scale are significantly different.
  • single-mode propagation can be expected due to the configuration of the clad portion 3 described later.
  • the clad portion 3 is provided around the core portion 2. That is, the clad portion 3 forms a band gap with respect to the light propagating in the core portion 2.
  • the clad portion 3 has a fractal aggregate structure portion 4 having a predetermined shape S formed by arranging a plurality of unit structure portions 5 having different refractive indexes with respect to the background material in a cross section orthogonal to the longitudinal direction of the core portion 2. A plurality of them are arranged so as to have sex.
  • the predetermined shape S is shown so as to surround the unit structure portion 5, but for example, the predetermined shape SS may be defined so as to connect the centers of the unit structure portion 5 on the outer peripheral side. In either case, the hexagonal shapes are similar.
  • the unit structure portion 5 is composed of materials having a refractive index different from that of the background material.
  • a hole gas such as air or vacuum
  • a material having a high or low refractive index with respect to the background material is used.
  • the material having a high or low refractive index are boron-added glass and fluoridated glass.
  • a case where the unit structure portion 5 is composed of holes will be described as an example.
  • the unit structure unit 5 is arranged as a unit element constituting the collective structure unit 4 in the cross section as shown in FIG. Further, the unit structure portion 5 is configured to be parallel to the core portion 2 in the longitudinal direction of the photonic band gap fiber 1.
  • the number of unit structure portions 5 included in the collective structure portion 4 is 19 in FIG. 1, but is not limited.
  • the collective structure portion 4 is configured by arranging a plurality of unit structure portions 5 in a grid pattern so as to have a predetermined shape S.
  • the collective structure can be, for example, a polygon, but as will be described later, the fractal property (for example, the shape connecting the centers of the collective structure portion 4 is arranged so as to have a similar relationship with the predetermined shape S). If satisfied, an appropriate shape can be adopted.
  • the predetermined shape S in the collective structure portion 4 is a hexagon. That is, the collective structure portion 4 is configured by arranging the unit structure portion 5 so as to form a hexagon.
  • the unit structure unit 5 and the collective structure unit 4 have two scales as parameters (FIG. 2).
  • the distance d1 between the centers of the unit structure portions 5 included in the aggregate structure portion 4 is set based on the wavelength of light. That is, the distance d1 between the centers of each unit structure portion 5 and the wavelength of light have a corresponding relationship.
  • the correspondence relationship is, for example, a positive correlation, and when the wavelength is long, the distance d1 between the centers of each unit structure portion 5 also becomes long.
  • the distance d1 between the centers of each unit structure portion 5 is set to a scale equivalent to the wavelength of light. For example, as shown in FIG.
  • the distance between the centers of the unit structure portion 5 is set to a value of about 2 to 20 ⁇ m (2 ⁇ or more and 20 ⁇ or less) when the wavelength of the light used is 1.07 ⁇ m.
  • the distance d2 between the centers of each collective structure portion 4 is set based on the intensity of light. That is, the distance d2 between the centers of each collective structure 4 and the light intensity (and transmission length) have a corresponding relationship.
  • the correspondence relationship is, for example, a positive correlation, and when the light intensity is high, the distance d2 between the centers of each collective structure portion 4 also becomes long.
  • the distance d2 between the centers is set so that the energy density when the circle having d2 as the diameter is the effective cross-sectional area A eff of light propagation is equal to or less than the generation threshold of induced Raman scattering.
  • the effective cross-sectional area A eff for lowering the generated energy density of induced Raman scattering can be estimated by the following equation (1).
  • P th is the input power to the fiber
  • g R is the Raman gain coefficient of the fiber, which is about 1 ⁇ 10 -13 m / W in the case of quartz glass
  • L is the length of the transmission fiber.
  • the distance between the centers of the collective structure portion 4 is set to about 60 ⁇ m or the like.
  • the diameter of the fiber is set to 200 ⁇ m
  • the diameter of the unit structure portion 5 is set to 8.64 ⁇ m, and the like.
  • the collective structure portion 4 arranged in the clad portion 3 is arranged so as to have a fractal structure (fractal property).
  • the fractal structure refers to a relationship in which the whole picture and a part are similar to each other (self-similarity).
  • the collective structure portion 4 forms a layer in the radial direction with the core portion 2 as the center.
  • the first layer (L1 in FIG. 2) and the second layer (L2 in FIG. 2) are formed is shown, but the number of layers can be appropriately set. ..
  • the collective structure portion 4 constituting each phase is arranged so that the shape connecting the centers of the collective structure portion 4 has a similar relationship with the predetermined shape S. As shown in FIG.
  • the shape S1 connecting the centers of the collective structure portions 4 in the first layer, the shape S2 connecting the centers of the collective structure portions 4 in the second layer, and the predetermined shape S of the collective structure portion 4 are similar to each other. It should be noted that the shape connecting the centers of the collective structure portions 4 in each layer and the core portion 2 have concentricity (the center points are common).
  • each pattern of the clad portion 3 is fractal with respect to the light propagating in the core portion 2, the shape connecting the centers of the collective structure portion 4 in each layer and the shape included in the shape.
  • the predetermined shape S of the collective structure portion 4 is similar to each other and is rotated by a predetermined rotation angle (not 0 °).
  • a relationship that is similar to each other and is rotated by a predetermined angle of rotation means that the figures are rotated by a predetermined angle of rotation about the center of one figure and scale conversion (enlargement or reduction) is performed. Means that is joint.
  • the predetermined side in the shape connecting the centers of the collective structure portion 4 and the predetermined side in the predetermined shape S of the collective structure portion 4 included in the shape are predetermined. It has an angle ⁇ .
  • the predetermined shape S of the collective structure portion 4 included in the shape includes a side forming an angle ⁇ .
  • the predetermined angle ⁇ is a value larger than 0 °. That is, in the second layer in FIG. 3, the shape connecting the centers of the collective structure portions 4 in the second layer and the collective structure portion 4 in the second layer are similar to each other and have a predetermined rotation angle. It becomes a relationship that is rotated only. The same relationship applies to the first layer (if there is another layer, the other layer).
  • the shape connecting the centers of the collective structure portion 4 and the predetermined shape S of the collective structure portion 4 included in the shape are similar to each other and are rotated by a predetermined rotation angle.
  • the fractal property can be appropriately recognized with respect to the light propagating in the core portion 2.
  • momentum and polarization retention characteristics can be expected.
  • the predetermined shape S of the collective structure portion 4 is a hexagon has been described, but the predetermined shape may be another shape such as a polygon.
  • the shape connecting the centers of the collective structure portion 4 and the predetermined shape S of the collective structure portion 4 included in the shape are rotated by a predetermined rotation angle (greater than 0 °) (aggregation).
  • the core portion 2 is formed by forming a predetermined angle between a predetermined side in a shape connecting the centers of the structural portions 4 and a predetermined side in a predetermined shape S of the collective structural portion 4 included in the shape).
  • the fractal property can be appropriately recognized for the propagating light.
  • the case where the shape connecting the centers of the collective structure portion 4 and the predetermined shape S of the collective structure portion 4 included in the shape are not rotated by a predetermined rotation angle (rotation angle is 0 °) (reference example) is shown in the figure. Shown in 4.
  • rotation angle is 0 °
  • FIG. 4 when the collective structure portion 4 is simply configured so that the diagonal lines of the polygons constituting the similar structures S1 and S2 and the diagonal lines of the collective structure portion 4 are parallel to each other (reference example), The propagating light cannot recognize each collective structure portion 4 corresponding to each layer, and cannot appropriately recognize the fractal property.
  • rotation may be clockwise or counterclockwise.
  • each characteristic is not limited to the examples shown in each figure. 5 to 8 show a cross-sectional view and band characteristics of the fiber in the reference example.
  • the band characteristic is a diagram showing the wavelength characteristic (wavenumber space) in the direction orthogonal to the longitudinal direction of the core (planar direction in the cross-sectional view). The wavelength of the light propagating (wavelength used) is also shown in each band characteristic for reference.
  • FIG. 5 is a reference example EX1 of a cross-sectional view of a high-power fiber when the core diameter is set large and holes equivalent to the core diameter are arranged around the core.
  • FIG. 6 shows band characteristics corresponding to the fiber of Reference Example EX1 of FIG.
  • FIG. 7 is a reference example EX2 of a cross-sectional view of a low-power fiber when the core diameter is set small and holes equivalent to the core diameter are arranged around the core.
  • FIG. 8 shows band characteristics corresponding to the fiber of Reference Example EX2 of FIG.
  • FIG. 9 shows an example of band characteristics corresponding to the photonic band gap fiber 1 according to the present embodiment shown in FIG.
  • the horizontal axis is the wave number and the vertical axis is the density of states of each wave number component.
  • the wave number corresponding to the wavelength of the propagating light (wavelength used) is set to WL.
  • the dispersion section in the lateral direction (direction orthogonal to the longitudinal direction of the core portion 2) in which one state of light can be taken is shown as area A. That is, in the area A, since the light spreads in the propagation direction in the lateral direction, the section on the wave number region where one state of the light can enter has a width.
  • the wave numbers due to the structure of the fiber are shown as P1, P2, P3a, and P3b.
  • the wave number resulting from the structure of this fiber shows different characteristics depending on the structure of the fiber as shown in FIGS. 6 and 8, and indicates the wave number (wavelength) that allows lateral propagation in the core portion 2. is there. That is, if the width between the wave numbers due to the structure of the fiber is equal to or greater than the lateral dispersion section in which one state of light can enter, the light does not propagate in the lateral direction (does not leak) and only in the longitudinal direction of the core. It will be propagated.
  • P1 is located in area A, which is a dispersion section in the lateral direction (direction orthogonal to the longitudinal direction of the core) in which one state of light can enter, so that P1 is located in area A. It takes a continuous energy level when viewed from the width resolution. This means that a part of light propagates (leaks) to the clad portion 3 regardless of the wave number. That is, it becomes a problem before single mode transmission.
  • the interval of P2 is as shown in FIG. Will be widened, and there will be two or more areas A. Therefore, since a lateral component of one state of light can enter each of the two areas A, not only the basic mode but also the higher-order mode is generated, and single-mode transmission cannot be performed.
  • the spacing between P3a and P3b can be appropriately set as shown in FIG. Therefore, only one area A can exist.
  • the lateral component (mode) of one state of light is only one of the area A in FIG. 9, single mode propagation can be performed more effectively.
  • P3a by arranging the collective structure portion 4 and P3b by arranging the unit structure portion 5. Therefore, only one area A, which is a dispersion section in the lateral direction (direction orthogonal to the longitudinal direction of the core) in which one state of light can enter, can be set in a region less than the wavenumber used, and a single mode can be achieved. Is possible.
  • the arrangement of the collective structure portion 4 and the unit structure portion 5 are arranged so that there is only one area A which is a dispersion section in the lateral direction (direction orthogonal to the longitudinal direction of the core) in which one state of light can enter.
  • Single mode can be expected by adjusting the arrangement.
  • the double grid point structure is a grid point structure configured with two types of hole spacing (N1 and N2 in FIG. 10). For example, as shown in FIG. 11, a higher-order propagation mode exists, resulting in a multi-mode. Note that FIG. 11 schematically shows beam profiles of higher-order modes up to the third order.
  • FIG. 13 is a diagram illustrating a more preferable configuration example of the photonic band gap fiber 1.
  • FIG. 13 simply shows a configuration corresponding to the first layer of FIG. 1, a second layer or the like may be added.
  • the angle ⁇ shown in FIG. 13 has the same definition as the angle ⁇ in FIG. Specifically, the angle formed by a specific side (W1 in FIG. 13) in the shape connecting the centers of each collective structure portion 4 and a specific side (W2 in FIG. 13) in the collective structure portion 4 in contact with the side. It becomes. Since a hexagon is assumed for W2 in the present embodiment, the collective structure portion 4 has sides and diagonal lines that are parallel to each other. Therefore, W2 may be defined for the sides or diagonally as shown in FIG.
  • the angle ⁇ is the diagonal line of the hexagon that is the shape (large structure) connecting the centers of each collective structure part 4. , It can be said that it is the smallest angle formed by the diagonal line of the hexagon of the collective structure part (small structure) 4.
  • W2 is a line orthogonal to Z1 as described later.
  • ⁇ is expressed as the following equation (3).
  • the angle ⁇ in the first layer (L1) becomes equal to the angle ⁇ in another layer such as the second layer (L2). That is, they form a hexagon by connecting the centers to each other, and the center of the hexagon forms a plurality of aggregated structure portions 4 equal to the center of the core portion 2 as one layer (L1, L2, etc.), and the clad portion 3 has a core.
  • a plurality of layers having different distances from the center of the portion 2 are formed, and the predetermined angles ⁇ are equal to each other in each layer.
  • the twist angle ⁇ 'described later is also equal in each layer, and the total of the angle ⁇ and the twist angle ⁇ 'in each layer is 30 °.
  • the angle may be defined as in the twist angle ⁇ 'in FIG.
  • a Cartesian coordinate system including an x-axis and a y-axis in a cross section is assumed. Assuming such a Cartesian coordinate system, it is assumed that the two sides of each hexagonal set structure portion 4 are parallel to the x-axis.
  • the twist angle ⁇ ' is formed by a straight line parallel to the y-axis (Z1 in FIG. 13) and a straight line passing through the center of the core portion 2 and the center of the collective structure portion 4 (Z2 in FIG. 13). It becomes a corner. In other words, Z2 is diagonal.
  • the twist angle ⁇ ' is an angle of 0 ° or more.
  • the twist angle ⁇ ' is as shown in the following equation (4).
  • FIG. 13 When the structure of FIG. 13 is decomposed, it can be considered as a direct product of a large structure and a small structure as shown in FIG. That is, as a large structure, when a plurality of collective structure portions 4 are put together, twisting occurs as in a twist angle ⁇ '. Then, when the collective structure portion 4 is viewed as a small structure, a twist occurs as in the angle ⁇ .
  • rotating W1 clockwise by 60 ° produces a line parallel to Z2
  • rotating W2 clockwise by 60 ° produces a line parallel to the diagonal line in the small structure.
  • the photonic bandgap fiber 1 having an appropriate fractal structure as shown in FIG. 13 can be configured.
  • FIG. 15 is a diagram schematically showing the collective structure portion 4 in a hexagonal shape based on FIG. 13.
  • a hexagon formed by connecting the centers of the unit structure portions 5 on the outer peripheral side in the unit structure portion 5 included in the collective structure portion 4 is shown as the shape 11.
  • the length E1 of one side of the shape 11 of the collective structure portion 4 is set to 6. This length is a length based on a certain unit length as 1.
  • the length of one side is 7 (that is, 7/6 times the length of one side of the collective structure 4) so as to surround the collective structure 4 (the centers are equal).
  • outer peripheral shape 14 that is, the length E2 is 7
  • the outer peripheral shapes 14 corresponding to the collective structure portions 4 are in contact with each other.
  • the gap 15 of each outer peripheral shape 14 becomes a triangle.
  • a complementary portion 7 described later is arranged in this gap.
  • the length E2 of one side of the hexagon of the outer peripheral shape 14 and the length E3 of one side of the triangle of the gap 15 have a relationship shown in FIG. 16 with the angle ⁇ .
  • the horizontal axis is the length of one side of the triangle with the gap 15 (the unit length is 1)
  • the vertical axis is the angle ⁇ .
  • the angle ⁇ is 16.10211 ° from FIG.
  • the angle ⁇ is 16.10211 °.
  • the angle ⁇ is controlled by the length E1 of one side of the hexagon and the length E3 of the side of the triangle with the gap 15. Further, assuming that the sum of the angle ⁇ and the twist angle ⁇ 'is 30 °, if the angle ⁇ is determined, the twist angle ⁇ 'is also determined.
  • each outer peripheral shape 14 is partially in contact with each other, and each collective structure portion 4 can be densely configured as shown in FIG. In particular, by configuring as shown in FIG. 15 (similar to FIG. 13), it is possible to effectively perform single-mode transmission (effectively suppress mode dispersion).
  • the configuration in which one collective structure portion 4 is missing as the core portion 2 is taken as an example, but the configuration of the core portion 2 is not limited.
  • the core portion 2 may have a configuration in which a plurality of collective structure portions 4 are missing.
  • FIG. 17 shows an example in which the seven collective structure portions 4 are missing in the core portion 2.
  • the refractive index of the clad portion 3 provided around the core portion 2 through which light is transmitted has a refractive index with respect to the background material. Since the collective structure portion 4 configured by using different unit structure portions 5 is arranged with fractal properties, it is possible to form a band structure by superimposing a band structure having a wide gap and a band structure having a narrow gap. Therefore, single mode transmission can be performed. By increasing the size of the core portion 2, high output and single mode transmission can be expected.
  • the shape connecting the centers of the collective structure portion 4 and the predetermined shape S of the collective structure portion 4 included in the shape have a similar relationship and are rotated by a predetermined rotation angle, they are conductive.
  • the fractal structure can be appropriately recognized by the light generated, and single-mode transmission (mode dispersion suppression) can be performed.
  • the predetermined shape S is a hexagon
  • the predetermined side in the shape connecting the centers of the collective structure portion 4 and the predetermined side in the predetermined shape S of the collective structure portion 4 included in the shape have a predetermined angle ⁇ .
  • the light transmission shape is distorted when viewed from a cross section (for example, a convex portion is formed around a circular shape).
  • the shape will be similar to that of the above. Since the beam profile of the light emitted from the laser transmitter is generally circular, the transmission shape is preferably circular.
  • a complementary portion 7 having a different refractive index with respect to the background material is formed in the gap region between the core portion 2 and the collective structure portion 4.
  • the gap region is a gap formed between the core portion 2 and the collective structure portion 4 arranged around the core portion 2, but the gap between the respective collective structure portions 4 also constitutes the complementary portion 7. May be good.
  • the gap is triangular. Therefore, a triangular complementary portion 7 is provided in the gap region.
  • the complementary portion 7 is provided in the gap region so as not to come into contact with each collective structure portion 4.
  • the shape of the complementary portion 7 is not limited to a triangular shape.
  • the complementary portion 7 is composed of materials having a refractive index different from that of the background material.
  • a hole gas such as air or vacuum
  • a material having a high or low refractive index with respect to the background material is used.
  • the material having a high or low refractive index are boron-added glass and fluoridated glass.
  • the complementary portion 7 is a hole.
  • the size of the complementary portion 7 (area in cross section) is not limited to the size shown in FIG.
  • the complementary portion 7 is used for each straight line connecting the midpoints of the opposing sides of the hexagon of the core portion 2.
  • the center is located in a straight line forming ⁇ clockwise or counterclockwise with the center of the hexagon of the core portion 2 as the axis.
  • the center of the hexagon is centered on the line connecting the midpoints of the opposite sides of the hexagon.
  • the center is located at an angle position ( ⁇ in FIG. 19) of about 16.1 ° from the equation (5).
  • the complementary portion 7 is arranged every 60 °.
  • the angle described in the equation (5) is the angle of the complementary portion 7 when the angle ⁇ is 16.10211 ° as shown in the equation (3).
  • the complementary portion 7 having a different refractive index with respect to the background material in the gap region between the core portion 2 and the collective structure portion 4. Therefore, it is possible to prevent the region where the light is conducted from becoming a distorted type (for example, a windmill type) and to make it closer to a circular shape. Therefore, it is possible to further improve the conductivity of light and the consistency with other devices connected to the photonic band gap fiber.
  • a distorted type for example, a windmill type
  • the photonic band gap fiber (1) described in each of the above-described embodiments is grasped as follows, for example.
  • the photonic band gap fiber (1) according to the present disclosure is provided around the core portion (2) through which light propagates and the core portion (2), and has a cross section orthogonal to the longitudinal direction of the core portion (2).
  • a plurality of collective structure parts (4) having a predetermined shape (S) formed by arranging a plurality of unit structure parts (5) having different refractive indexes with respect to the background material are arranged so as to have fractal properties.
  • a predetermined side in a shape connecting the centers of the collective structure portion (4) and a predetermined side in a predetermined shape of the collective structure portion (4) included in the shape form a predetermined angle larger than 0 °.
  • a clad portion (3) is provided.
  • the photonic band gap fiber (1) According to the photonic band gap fiber (1) according to the present disclosure, a unit structure having a different refractive index with respect to a background material in a clad portion (3) provided around a core portion (2) through which light is transmitted. Since the collective structure part (4) formed by using the part (5) is arranged with fractal properties, it is possible to form a band structure by superimposing a band structure having a wide gap and a band structure having a narrow gap. it can. Therefore, single mode transmission or mode dispersion suppression can be performed. By increasing the size of the core portion (2), high output and single mode transmission can be expected.
  • the predetermined side in the shape connecting the centers of the collective structure portion and the predetermined side in the predetermined shape of the collective structure portion included in the shape are made conductive by forming a predetermined angle.
  • the fractal structure can be recognized more effectively with respect to light. That is, it becomes possible to more effectively perform single-mode transmission or mode dispersion suppression.
  • the distance between the centers of the unit structure portions (5) included in the aggregate structure portion (4) corresponds to the wavelength of the light. May have.
  • the distance between the centers of each unit structure portion (5) included in the aggregate structure portion (4) is set based on the wavelength of light. It is possible to appropriately transmit light of a wavelength. In addition, single-mode transmission or mode dispersion suppression is possible by adapting to the wavelength.
  • the distance between the centers of the collective structure portions (4) may have a corresponding relationship with the light intensity in the cross section.
  • the photonic band gap fiber (1) when the light intensity is strong (high output) by setting the distance between the centers of each collective structure (4) based on the light intensity. Even if it is), it is possible to deal with it.
  • the photonic band gap fiber (1) has a shape in which the collective structure portion (4) is provided around the core portion (2) and connects the centers of the collective structure portion (4). May be arranged so as to have a similar relationship with the predetermined shape (S).
  • the shape connecting the centers of the collective structure portion (4) is arranged so as to have a similar relationship with the predetermined shape (S), and thus is appropriately fractal. It can be a structure.
  • the photonic band gap fiber (1) has a predetermined shape (S) having a polygonal shape, and has a shape connecting the centers of the collective structure portion (4) and the collective structure portion included in the shape.
  • the predetermined shape (S) of (4) may have a similar relationship with each other and may be rotated by a predetermined rotation angle.
  • the shape connecting the centers of the collective structure portion (4) and the predetermined shape (S) of the collective structure portion (4) included in the shape are defined as each other. Since they have a similar relationship and are rotated by a predetermined rotation angle, the fractal structure can be appropriately recognized by the conducting light, and single-mode transmission or mode dispersion suppression can be performed.
  • the photonic band gap fiber (1) has a hexagonal predetermined shape (S), and is included in the predetermined side in the shape connecting the centers of the collective structure portion (4) and the shape.
  • the predetermined side of the collective structure portion (4) in the predetermined shape (S) may have a predetermined angle ( ⁇ ).
  • the predetermined shape (S) is a hexagon
  • the predetermined side in the shape connecting the centers of the collective structure portion (4) and the shape are formed.
  • the fractal structure can be appropriately recognized by the conducting light, and single mode transmission or It is possible to suppress mode dispersion.
  • the photonic band gap fiber (1) according to the present disclosure may be represented by the formula (6) when the predetermined angle ( ⁇ ) is ⁇ .
  • the equation (6) corresponds to the above equation (2).
  • the photonic band gap fiber (1) According to the photonic band gap fiber (1) according to the present disclosure, it is possible to appropriately configure a fractal structure.
  • the photonic band gap fiber (1) according to the present disclosure may be represented by the following equation (7) when the predetermined angle is ⁇ .
  • the equation (7) corresponds to the above equation (3).
  • the photonic band gap fiber (1) forms a hexagon by connecting the centers to each other, and the center of the hexagon forms a plurality of the collective structure portions (4) equal to the center of the core portion (2).
  • a plurality of layers having different distances from the center of the core portion (2) are formed in the clad portion (3), and even if the predetermined angles are equal to each other in each layer. Good.
  • a fractal structure can be appropriately formed even in the case of a polyphase structure.
  • the occurrence of higher-order modes can be suppressed more effectively by setting a predetermined angle as ⁇ shown in the equation (7).
  • each of the collective structure portions (4) which are hexagonal, are described above.
  • a straight line parallel to the x-axis, passing through the center of the core portion and parallel to the y-axis, and a straight line passing through the center of the core portion and the center of the collective structure portion (4) have a twist angle of 0 ° or more. May have.
  • a straight line passing through the center of the core portion (2) and parallel to the y-axis, the center of the core portion (2), and the center of the collective structure portion (4) are defined.
  • the straight line passing through has a twist angle of 0 ° or more, so that the occurrence of the higher-order mode can be suppressed more effectively.
  • the total of the predetermined angle and the twist angle may be 30 °.
  • the total of the predetermined angle and the twist angle is 30 °, so that the light passing through the core portion (2) is more effectively converted to the single mode. You can get closer.
  • a straight line passing through the center of the core portion (2) and parallel to the y-axis, the center of the core portion (2), and the center of the collective structure portion (4) are defined.
  • a complementary portion (with a different refractive index with respect to the background material) ( 7) may be configured.
  • the complementary portion (7) having a different refractive index with respect to the background material is provided in the gap region between the core portion (2) and the collective structure portion (4). Since it is provided, it is possible to prevent the region where the light is conducted from becoming a distorted type (for example, a windmill type) and to make it closer to a circular shape. Therefore, it is possible to further improve the conductivity of light and the consistency with other devices connected to the photonic band gap fiber (1).
  • a distorted type for example, a windmill type
  • the complementary portion (7) has the predetermined shape as a hexagon and the core portion (2) has a hexagon having the same shape as the predetermined shape.
  • the equation (7) is clockwise or counterclockwise with the center of the hexagon of the core portion (2) as the axis. The center may be located in a straight line forming ⁇ in).
  • the equation (7) corresponds to the above equation (5).
  • the complementary portion (7) can be appropriately arranged in the gap region between the core portion (2) and the collective structure portion (4). That is, the region where light conducts can be made closer to a circular shape.
  • the core portion (2) has holes, a material equal to the background material, a material having a refractive index different from that of the background material, or the collective structure portion (the aggregate structure portion). It may be configured by using 4).
  • the core portion (2) there are holes (for example, air or vacuum), a material equal to the background material, a material having a refractive index different from that of the background material, or
  • a material equal to the background material for example, air or vacuum
  • a material having a refractive index different from that of the background material or
  • the collective structure portion (4) in the core portion (2) has the same structure as the collective structure portion (4) in the clad portion (3), and specifically, the refractive index is higher than that of the background material.
  • the laser apparatus according to the present disclosure includes the above-mentioned photonic band gap fiber (1).
  • the predetermined angle ⁇ has been described as 13.00391 ° from the equation (2), but the angle ⁇ is not limited to the equation (2) as long as it is an angle larger than 0 °.
  • fractal structure is shown in each of the first embodiment and the second embodiment described above, it is merely an example and can be changed without departing from the gist of the present disclosure.
  • a cross-sectional view may be configured as shown in FIG. In the example of FIG. 20, the angle ⁇ is given by the following equation (11).
  • the total of the angle ⁇ and the twist angle ⁇ ' is 30 °, and a photonic band gap fiber having an appropriate fractal structure can be configured.
  • FIGS. 21 and 22 show the angle ⁇ as a diagonal line having a large structure and a diagonal line having a small structure.
  • FIG. 21 is an example when the angle ⁇ is 30 °. That is, the smallest angle formed by the diagonal line of the large structure and the diagonal line of the small structure is the angle ⁇ , which is 30 °.
  • the twist angle ⁇ ' 0 °, and the sum of the angle ⁇ and the twist angle ⁇ 'is 30 °.
  • FIGS. 4 and 22 are examples when the angle ⁇ is set to 0 °. That is, the diagonal line of the large structure and the diagonal line of the small structure shown in FIG.
  • Photonic band gap fiber 2 Core part 3: Clad part 4: Collective structure part 5: Unit structure part 7: Complementary part

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

La présente invention a pour objet de réaliser une fibre à bande interdite photonique et un dispositif laser qui sont capables de supprimer la dispersion de mode à des rendements élevés. Une fibre à bande interdite photonique (1) comprend : une partie d'âme (2) à travers laquelle se propage de la lumière ; et une partie de gainage (3) qui est disposée autour de la partie d'âme (2) et qui est constituée de telle sorte que dans une section transversale orthogonale à la direction longitudinale de la partie d'âme (2), une pluralité de parties de structure d'agrégat (4) ayant une forme prédéterminée S sont disposées de façon à posséder des caractéristiques fractales, les parties de structure d'agrégat (4) étant chacune constituées d'une pluralité de parties de structure unitaire (5) ayant des indices de réfraction différents par rapport à un matériau de fond, et un côté prédéterminé de la forme formée en joignant les centres des parties de structure d'agrégat (4) formant un angle prédéterminé avec un côté prédéterminé de la forme prédéterminée des parties de structure d'agrégat (4) incluses dans ladite forme.
PCT/JP2020/023217 2019-09-24 2020-06-12 Fibre à bande interdite photonique et dispositif laser WO2021059618A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2021548340A JP7135220B2 (ja) 2019-09-24 2020-06-12 フォトニックバンドギャップファイバ及びレーザ装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019172987 2019-09-24
JP2019-172987 2019-09-24

Publications (1)

Publication Number Publication Date
WO2021059618A1 true WO2021059618A1 (fr) 2021-04-01

Family

ID=75166894

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2020/023217 WO2021059618A1 (fr) 2019-09-24 2020-06-12 Fibre à bande interdite photonique et dispositif laser

Country Status (2)

Country Link
JP (1) JP7135220B2 (fr)
WO (1) WO2021059618A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006003889A1 (fr) * 2004-06-30 2006-01-12 Mitsubishi Cable Industries, Ltd. Fibre de cristal photonique
WO2008098338A1 (fr) * 2007-02-15 2008-08-21 Institut National D'optique Fibre optique microstructurée à réseau de type archimède
US20100046560A1 (en) * 2008-08-21 2010-02-25 Jian Liu Dispersion managed fiber stretcher and compressor for high energy/power femtosecond fiber laser
US20120148207A1 (en) * 2010-12-09 2012-06-14 University Of Central Florida Research Foundation, Inc. Waveguides Configured To Simultaneously Guide Electromagnetic Waves Of Different Wavelengths
JP2014067053A (ja) * 2004-01-16 2014-04-17 Imra America Inc 大コア穴あきファイバ
CN104898199A (zh) * 2015-06-26 2015-09-09 深圳市通盛新材料有限公司 一种多芯光子晶体光纤与激光器光源的连接结构

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014067053A (ja) * 2004-01-16 2014-04-17 Imra America Inc 大コア穴あきファイバ
WO2006003889A1 (fr) * 2004-06-30 2006-01-12 Mitsubishi Cable Industries, Ltd. Fibre de cristal photonique
WO2008098338A1 (fr) * 2007-02-15 2008-08-21 Institut National D'optique Fibre optique microstructurée à réseau de type archimède
US20100046560A1 (en) * 2008-08-21 2010-02-25 Jian Liu Dispersion managed fiber stretcher and compressor for high energy/power femtosecond fiber laser
US20120148207A1 (en) * 2010-12-09 2012-06-14 University Of Central Florida Research Foundation, Inc. Waveguides Configured To Simultaneously Guide Electromagnetic Waves Of Different Wavelengths
CN104898199A (zh) * 2015-06-26 2015-09-09 深圳市通盛新材料有限公司 一种多芯光子晶体光纤与激光器光源的连接结构

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DÍAZ-SORIANO A., ORTIZ-MORA A., DENGRA A.: "A new low-dispersion and large-effective-area PCF based on a fractal design", OPTICAL FIBER TECHNOLOGY, vol. 21, 16 September 2014 (2014-09-16), pages 69 - 72, XP055808869 *

Also Published As

Publication number Publication date
JPWO2021059618A1 (fr) 2021-04-01
JP7135220B2 (ja) 2022-09-12

Similar Documents

Publication Publication Date Title
WO2013051485A1 (fr) Fibre optique à âmes multiples et rétention de polarisation
JP6289401B2 (ja) スポットサイズ変換器
JP5990419B2 (ja) 光学入出力デバイス
US20040184156A1 (en) Polarization splitting grating couplers
JP2003107266A (ja) 偏波保持光ファイバおよび絶対単一偏波光ファイバ
Zhang et al. Design of polarization splitter with single-polarized elliptical-hole core circular-hole holey fibers
WO2017033584A1 (fr) Fibre multicœur et câble optique
JP2011033899A (ja) ホーリーファイバ
WO2021059618A1 (fr) Fibre à bande interdite photonique et dispositif laser
JP3484165B2 (ja) 偏波保持光ファイバ
JP2011118223A (ja) モード変換素子
WO2019159345A1 (fr) Dispositif optique intégré à semi-conducteur
JP2003337239A (ja) 分散シフト光ファイバ
JP6578016B2 (ja) 光ファイバ設計方法
JPH11248957A (ja) 界分布変換光ファイバおよびその界分布変換光ファイバを用いたレーザダイオードモジュール
US7260300B2 (en) Waveguide element using photonic crystal
US10310177B2 (en) Photonic crystal fiber
JP6446140B2 (ja) 光ファイバ及び光伝送システム
Lin et al. Sensitivity to termination morphology of light coupling in photonic-crystal waveguides
JP2007017494A (ja) フォトニック結晶導波路
JP5306580B2 (ja) ハニカム格子型フォトニックバンドギャップファイバとその製造方法
JP4956741B2 (ja) フォトニック結晶導波路
JP6697365B2 (ja) モード合分波光回路
JP5598668B2 (ja) スプリッタ
JP6927094B2 (ja) 光導波路接続構造

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20869968

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021548340

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20869968

Country of ref document: EP

Kind code of ref document: A1