43results about How to "Reduce limit loss" patented technology

The invention discloses a single-polarization single-mode photonic crystal fiber with high nonlinearity. The cross section of the photonic crystal fiber comprises a fiber core and a cladding. The-cladding is a peripheral region which is the same as the normal photonic crystal fiber and is formed by evenly distributed air holes (2) with the same structure. The fiber core is composed of a substrate material (1) which is arranged on the center of the optical fiber end face as well as four high-ellipticity air holes (3) which are closely arranged, not mutually overlapped and in rectangular distribution. In the photonic crystal fiber, a cut off characteristic of two polarization modes of a basic mode can be adjusted by finely adjusting distance between centers of air holes, which causes one of the polarization modes to be cut off in the applied waveband, thus realizing the wide-bandwidth single polarization transmission. Meanwhile, the air holes (3) suppress the generation of high order mode, which allows the cladding to use a higher air filling rate on the premise of not changing the single-mode transmission characteristic of the optical fiber, therefore the mode area and the confinement loss are reduced. The single-polarization single-mode photonic crystal fiber with the high nonlinearity solves the problem that the high nonlinearity, low confinement loss and wide band single-polarization single-mode characteristic can not be realized at the same time in the existing photonic crystal fiber technology.

The present invention provides a microstructured hollow-core optical fiber. The optical fiber comprises first type medium circular tubes, second type medium circular tubes, and a third type medium circular tube; the first type medium tubes are nested in the second type medium circular tubes and are periodically distributed along the circumference of the second type medium circular tubes; intervalsbetween the outer walls of the adjacent first type medium circular tubes are greater than 0; the second type medium circular tubes are nested in the third type medium circular tube; and the first type medium circular tubes, the second type medium circular tubes and the third type medium circular tube are connected with one another in a tangent or intersecting manner. According to the microstructured hollow-core optical fiber of the invention, confinement loss can be lowered by simply increasing the number of the second type medium circular tubes, so that a difficulty that the confinement lossof a negative-curvature anti-resonant hollow-core optical fiber cannot be reduced by simply adopting a means of increasing annular layers which assists in reducing the confinement loss of a hollow-core photonic band gap optical fiber can be eliminated. According to the optical fiber provided by the invention, too many nodes will not be introduced into the cross section of the optical fiber, and anew scheme and idea can be provided for the design and manufacture of a broadband low-loss hollow-core optical fiber.

The invention discloses a panda-liked high birefringence photonic crystal fiber. A pair of large air holes are respectively replaced with seven small air holes; and the transverse space among the cladding air holes is different from the horizontal space among the cladding air hole; therefore, the structural fiber has duplicate rotational symmetry; the orthogonally polarizing mode is no longer degenerated, which appears high birefringence. The panda like type of high birefringence photonic crystal fiber can maintain single mode transmission within a wide wavelength range; the birefringence of the mode is one order of magnitude higher than the birefringence of the common fiber at least. The structural fiber has low restriction consumption, large numerical aperture and adjustable dispersion. Therefore, the PCF with the structure can be used for the manufacture of the polarization maintaining fiber and the related fiber device, which are provided with suitable dispersion and polarization characteristics. The invention has very small temperature influence and good stability.

The invention discloses a multi-resonance-layer hollow-core optical fiber, which comprises an annular dielectric pipe, wherein a first type hole is formed in the central position in the annular dielectric pipe; a plurality of groups of arc-shaped dielectric layers are arranged around the first type hole, a rectangular dielectric layer is arranged on the inner side of each arc-shaped dielectric layer; a second type hole is formed between every two groups of arc-shaped dielectric layers in the same arc direction; third type holes are formed between each rectangular dielectric layer and the innerwall of the annular dielectric pipe and between each rectangular dielectric layer and the corresponding arc-shaped dielectric layer, a fourth type hole is formed between every two groups of adjacentrectangular dielectric layers, the first type hole, the second type holes, the third type holes and the fourth type holes form a low-refractive-index region, and the arc-shaped dielectric layers, therectangular dielectric layers and the annular dielectric pipe form a high-refractive-index region. The multi-resonance-layer hollow-core optical fiber has the beneficial effects that the damage threshold of the optical fiber is improved; the confinement loss of the optical fiber is reduced, and the low confinement loss features can be obtained conveniently; and high-bandwidth and low-loss opticaltransmission can be obtained in a facilitated manner.

The invention discloses a supermode microstructure optical fiber for transmitting orbital angular momentum. The supermode microstructure optical fiber comprises: a central air hole, a substrate material, a ring array fiber core area and a cladding layer area, wherein the circle center of the central air hole is located at the center of the optical fiber, the ring array fiber core area comprises anoptical fiber substrate and a plurality of doped quartz columns uniformly arranged along the central air hole, the cladding layer area is located on the outer side of the ring array fiber core area and share the circle center with the central air hole, the cladding layer area is a circular microstructure cladding layer composed of a first cladding layer, a second cladding layer, a third claddinglayer and a fourth cladding layer, wherein the first cladding layer, the second cladding layer, the third cladding layer and the fourth cladding layer are respectively composed of 42, 48, 54 and 60 circular air holes which are annularly and uniformly arranged. The working wavelength range of the optical fiber disclosed by the invention is 1.0 to 1.8 um, 60 orbital angular momentum modes can be supported within the working wavelength range, the limiting loss of the modes is low, the dispersion is small, and the effective mode area is large.

A hollow negative curvature photonic crystal fiber with high birefringence and low loss comprises an optical fiber tube body which has a circular cross section and is hollow inside. The tube wall of the optical fiber tube body comprises inner and outer layers of circular ring structures. Two large capillary tubes internally tangent to an optical fiber interlayer are arranged in the hollow core ofthe optical fiber tube body in a bilateral symmetry manner. Three small capillary tubes which are internally tangent to the optical fiber interlayer and are the same are arranged in the hollow core ofthe optical fiber tube body above and below the space between the two large capillary tubes. A medium capillary tube internally tangent to the corresponding large capillary tube is arranged in each of the two large capillary tubes. The small capillary tubes, the medium capillary tubes and the large capillary tubes are bilaterally symmetrical. A light wave transmission cavity defined by the smallcapillary tubes and the large capillary tubes is formed in the center of the hollow core of the optical fiber tube body. The optical fiber tube body, the large capillary tubes, the medium capillary tubes and the small capillary tubes are all made of silica glass. The optical fiber is simple in structural design, the adjustable range of capillary structure parameters is large, and industrial preparation and commercial application of HCF can be achieved.

The invention relates to an air hole square array fiber core annular doping four-core photonic crystal fiber, which comprises a fiber cladding and fiber cores, wherein the fiber cladding is formed by distributing a plurality of layers of air hole square arrays; the fiber core is formed by four groups of units lack of air holes; and the four fiber cores are symmetrically distributed at diagonal lines of four quadrants. Each fiber cores comprises an inner core and a doping annular area, wherein the inner core and the fiber cladding are made of quartz materials, and the doping annular area wrapped outside the inner core is made of quartz doped with an oxide capable of increasing a refractive index, so that the refractive index of the doping annular area is a little higher than that of the fiber core. With the adoption of the fiber core annular doping four-core structure, the mode area can be efficiently increased, and the nonlinear effect can be reduced. The fiber core annular doping can form a flat mode field, thereby efficiently reducing the thermal damage effects of the fiber. The fiber cladding is formed by distributing the plurality of layers of air hole square arrays, so that the ultralow limit loss can be realized, and the energy loss can be greatly reduced in the transmitting process.

The invention discloses an ultra-large positive dispersion ZBLAN fluoride photonic crystal optical fiber, and relates to the field of dispersion compensating devices in an optical fiber communication system. The optical fiber comprises a core, an inner cladding covering the core, and an outer cladding covering the inner cladding. The inner cladding is in a regular hexagonal structure composed of two layers of small air hole channels. The outer cladding is in a regular hexagonal structure composed of four layers of large air hole channel. The cross-sectional area of each large air hole channel does not exceed 2 times the cross-sectional area of each small air hole channel. According to the invention, the positive dispersion of the optical fiber in the wavelength range of 1.8 microns to 3.6 microns by designing the internal structure of the fluorinated optical fiber, and especially the maximum positive dispersion value of -351.3ps / km / nm is acquired at 2.9 microns; the low-limit loss of 0.05dB / m is kept; and the dispersion generated in a laser cavity is compensated to near-zero dispersion to acquire ultra-short and high-energy pulse.

The invention discloses a cladding pumping single-mode terahertz fiber laser, and the laser comprises a continuous tunable carbon dioxide laser, a zinc selenide convex lens, a zinc selenide concave lens, a mid-infrared hollow-core fiber, a copper-plated reflecting mirror with a centrifugal hole, a composite single-mode terahertz hollow-core fiber and a gold-plated quartz crystal output mirror, which are arranged in sequence; two ends of the mid-infrared hollow-core fiber are respectively connected with a fiber adapter; after the single-mode terahertz hollow-core fiber is connected with the fiber adapter, the two ends of the single-mode terahertz hollow-core fiber are connected with a vacuum air chamber I and a vacuum air chamber II respectively, the copper gold-plated reflecting mirror with the centrifugal holes is packaged in the vacuum air chamber I through a flange, and the gold-plated quartz crystal output mirror is packaged in the vacuum air chamber II through a flange. A vacuumizing system is further connected between the vacuum air chamber I and the vacuum air chamber II, and air pressure control is conducted through the vacuum valve I and the vacuum valve II. The laser overcomes the defects that an ordinary optical pump terahertz laser is large in size and low in light beam quality, and high-power single-mode terahertz output is difficult to achieve.

A multi-resonant layer hollow-core optical fiber of the present invention comprises a ring-shaped dielectric tube, a first type of hole is arranged at the inner center of the ring-shaped dielectric tube, and several groups of arc-shaped dielectric layers are arranged around the first type of hole, and A rectangular dielectric layer is arranged on the inner side of the arc-shaped dielectric layer, and a second type of hole is arranged between two groups of arc-shaped dielectric layers in the same arc direction. The third type of hole is formed between the dielectric layers, the fourth type of hole is formed between two adjacent rectangular dielectric layers, the first type of hole, the second type of hole, the third type of hole and the fourth type of hole form a low refractive index area, The arc-shaped dielectric layer, the rectangular dielectric layer and the ring-shaped dielectric tube form a high refractive index area. Beneficial effects: the damage threshold of the optical fiber is increased; the limited loss of the optical fiber is reduced, which is beneficial to obtain low limited loss characteristics; and is beneficial to obtain optical transmission with high bandwidth and low loss.

The invention discloses a photonic crystal fiber. The photonic crystal fiber is characterized by comprising a core layer, a cladding layer and a coating layer from inside to outside, wherein the crosssection of the fiber is circular, the core layer, the cladding layer and the coating layer are concentric, the core layer is the inner-most layer of the fiber, the center of the cross section of thecore layer has a circular hole, the cladding layer is internally provided with multiple fan-shaped ring air holes uniformly, the cladding layer comprises four cladding rings, each cladding ring has same-size fan-shaped ring air holes, the air holes are sequentially adjacent, the sizes of the fan-shaped ring air holes of in the cladding rings gradually increase from inside to outside, intervals ofthe cladding rings are the same, the coating layer is the outer-most layer, the core layer and the cladding layer are respectively prepared from silica crystal or silicon crystal, and the coating layer is prepared from acrylate or silicone resin. The photonic crystal fiber is advantaged in that multiple orbital angular momentum modes can be transmitted, effective refractive index difference of the mode group reaches 10-3 magnitude, limit loss is low, a nonlinear coefficient is small, and dispersion is low.

The invention discloses a supermode microstructure optical fiber for transmitting orbital angular momentum. The supermode microstructure optical fiber comprises: a central air hole, a substrate material, a ring array fiber core area and a cladding layer area, wherein the circle center of the central air hole is located at the center of the optical fiber, the ring array fiber core area comprises anoptical fiber substrate and a plurality of doped quartz columns uniformly arranged along the central air hole, the cladding layer area is located on the outer side of the ring array fiber core area and share the circle center with the central air hole, the cladding layer area is a circular microstructure cladding layer composed of a first cladding layer, a second cladding layer, a third claddinglayer and a fourth cladding layer, wherein the first cladding layer, the second cladding layer, the third cladding layer and the fourth cladding layer are respectively composed of 42, 48, 54 and 60 circular air holes which are annularly and uniformly arranged. The working wavelength range of the optical fiber disclosed by the invention is 1.0 to 1.8 um, 60 orbital angular momentum modes can be supported within the working wavelength range, the limiting loss of the modes is low, the dispersion is small, and the effective mode area is large.

The invention discloses a photonic crystal optical fiber which is characterized in that the photonic crystal optical fiber comprises a core layer, a cladding layer and a coating layer from the insideto the outside, the cross section of the optical fiber is circular, the core layer, the cladding layer and the coating layer are concentric, the core layer is located at the innermost layer of the optical fiber, and the center of the cross section of the core layer is a circular hole, a plurality of semi-elliptical air holes are uniformly arranged in the cladding layer, the cladding layer includesfive cladding rings, multiple air holes with the same size are uniformly arranged in each of the cladding rings, the air holes in the cladding rings are in a circular array arrangement with the center of the core layer as a center original point, the sizes of the air holes in the cladding rings are gradually increased from the inner ring to the outer ring, the long axes of the semi-elliptical pores are directed to the center of the core layer, both the core layer and the cladding layer are made of silica crystal or silicon crystal, and the coating layer is made of acrylate or silicone resin.The photonic crystal optical fiber of the invention can transmit a plurality of orbital angular momentum modes, the effective refractive index difference of a mode group reaches an order of 10<-3>, the confinement loss is low, the nonlinear coefficient is small, and the dispersion is low.

The invention provides an anti-resonance hollow-core optical fiber. The anti-resonance hollow-core optical fiber is composed of a first-type dielectric tube, a second-type dielectric tube and a first-type dielectric layer and comprises a cladding region with high refractive index and a fiber core region with low refractive index; the first-type dielectric tube and the first-type dielectric layer are both connected to the second-type dielectric tube; the area surrounded by the outer wall, close to the core region, of the first type dielectric tube is a fiber core region (a first-type hole); a second-type hole is isolated between the first-type dielectric tube and the first-type dielectric layer; and a third-type hole is isolated between the first-type dielectric tube and the second-type dielectric tube. The fiber core of the optical fiber has a negative curvature boundary; the optical fiber is provided with a plurality of anti-resonance layers; the cladding of the optical fiber has no nodes, so that the leakage loss is effectively reduced; the optical fiber has no loss peak value caused by transverse nodes, so that transmission bandwidth is increased; besides, optical fiber modes are mainly distributed in air holes, so that the material absorption loss of the optical fiber can be effectively reduced, the damage threshold of the optical fiber is improved, and high-power laser and terahertz waves can be effectively transmitted.

This invention relates to all solid band gap fibers with a restricted low loss and low bending loss, which includes a core-layer and a cladding layer, the features are: the cladding materials have a refractive index n1, and the basic units with high doped materials with a refractive index n3, which locates on the regular mesh nodes of the cladding layer, and the high doping region of each basic unit are wrapped around with at least one belt region at a low refractive index n2. The invention can be widely applied in the field of photonic optical devices, for instance the fiber amplifier and fiber laser of rare earth doping, and writing for fiber grating etc.

The invention discloses a double-cladding hollow-core anti-resonance optical fiber with a heterostructure, and relates to the technical field of special optical equipment. Comprising a hollow-core anti-resonance optical fiber unit, an inner cladding sleeving the outer layer of the hollow-core anti-resonance optical fiber unit, an outer cladding sleeving the outer layer of the inner cladding, a quartz glass supporting tube sleeving the outer layer of the outer cladding, and a polymer coating sleeving the outer layer of the quartz glass supporting tube. Each hollow-core anti-resonance optical fiber unit comprises an air fiber core and six cladding round tubes with the same size, elliptical anti-resonance tubes are nested in the cladding round tubes, the spacing distances among the cladding round tubes are the same, and the space in the air fiber core area and the space in other hollow-core anti-resonance optical fiber units are all air; the outer cladding layer is composed of 33 circular tubes with the same size, and the thickness and the material of the circular tubes are consistent with those of the cladding layer circular tubes. According to the invention, the low-loss transmission of the pump light is realized, the energy leakage is avoided, the limiting loss of the pump light is reduced, and the transmission efficiency of the inner cladding is improved.

The invention relates to the technical field of optical fiber communication, and discloses a double-layer weak-coupling few-mode hollow anti-resonance optical fiber which comprises an outer wrapping area and a fiber core area. The fiber core area is arranged in the outer wrapping area, and the fiber core area and the outer wrapping area are concentric circles; the outer wrapping area comprises an outer wrapping layer, a plurality of second-layer nested tubes and a plurality of first-layer anti-resonance tubes; the second-layer nested tubes are internally tangent to the outer wrapping layer; the first-layer anti-resonance tubes are located between the second-layer nested tubes and the fiber core area and are tangent to the second-layer nested tubes and the fiber core area respectively; the plurality of second-layer nested tubes are uniformly and circumferentially distributed at equal intervals and surround the fiber core area; and the plurality of first-layer anti-resonance tubes are arranged at equal intervals, are uniformly and circumferentially distributed and surround the fiber core area. The problems that an existing optical fiber lacks flexible optimization capacity and does not support few-mode weak coupling transmission, and the limited loss of a transmission mode is large are solved.

The invention discloses a photonic crystal fiber, which is characterized by comprising a core layer, a cladding layer and a coating layer from the inside to the outside, wherein the cross section of the fiber is circular, the core layer, the cladding layer and the coating layer are concentric, the core layer is arranged at the innermost layer of the fiber, the center of the cross section of the core layer is a circular hole, a plurality of semicircular air holes are uniformly formed in the cladding layer, the cladding layer comprises five cladding layer rings, each of the cladding layer ring is formed by sequentially connecting the semicircular air holes of the same size, the sizes of the semicircular air holes in the cladding layer rings are progressively increased in sequence from the inner ring to the outer ring, convex surfaces of the semicircular air holes in every two adjacent rows of cladding layer rings, the coating layer is arranged at the outermost layer, the core layer and the cladding layer are made of silicon dioxide crystals or silicon crystals, and the coating layer is made of acrylate or organic silicon resin. The photonic crystal fiber disclosed by the invention can transmit a plurality of orbital angular momentum modes, the effective refractivity difference of the mode group reaches 10<-3> magnitude order, the confinement loss is low, the nonlinear coefficientis small, and the chromatic dispersion is low.

The invention discloses a hollow-core anti-resonance optical fiber with a ginkgo leaf-shaped cladding. The hollow-core anti-resonance optical fiber sequentially comprises an optical fiber outer sleeve, ginkgo leaf-shaped cladding tubes and an air fiber core from outside to inside; the ginkgo-leaf-shaped cladding tubes meet the anti-resonance reflection waveguide (ARROW) principle in design and are specifically made of glass, the thickness of the ginkgo-leaf-shaped cladding tubes is t, the whole ginkgo-leaf-shaped cladding tubes are in a neat ginkgo leaf shape after winding and are specifically composed of a front arc section and two rear arc sections, the front arc section and the rear arc sections have negative curvature relative to the air fiber core and bend towards the outer side of the air fiber core; and the plurality of ginkgo leaf-shaped cladding tubes are fixed on the optical fiber outer sleeve in a rotational symmetry manner.

The invention discloses a novel photonic crystal fiber capable of transmitting a plurality of OAM (orbital angular momentum) modes. The novel photonic crystal fiber comprises a central fiber core, an annular high-refraction-index layer, a first coating layer, a second coating layer, a third coating layer and a fourth coating layer, wherein the central fiber core utilizes round air holes, and the central fiber core is covered by the annular high-refraction-index layer; the first coating layer is composed of 36 square air holes, and a rotation angle of adjacent air holes around the circle center is theta 1; the second coating layer is composed of 40 square air holes, and a rotation angle of adjacent air holes around the circle center is theta 2; the third coating layer is composed of 45 square air holes, and a rotation angle of adjacent air holes around the circle center is theta 3; the fourth coating layer is composed of 50 square air holes, and a rotation angle of adjacent air holes around the circle center is theta 4; a substrate material of each coating layer is quartz, the square air holes of all the coating layers are the same in size, the distances between the adjacent coating layers are the same, and the coating layers are symmetrically distributed in a round shape around the central fiber core. The novel photonic crystal fiber can support as many as 58 OAM modes, can transmit a plurality of HE and EH modes and can remarkably improve optical communication capacity.

The invention discloses a twisted optical fiber and a manufacturing method thereof. The twisted optical fiber comprises a fiber core, a cladding layer and a coating layer which are sequentially arranged from inside to outside, wherein the cladding layer contains an annular stress region, and the annular stress region is in contact or not in contact with the fiber core; and the size and thermal expansion coefficient of the annular stress region satisfy the condition that: |Delta alpha|*zeta>=0.2. The manufacturing method of the twisted optical fiber comprises the steps of: step 1, depositing the cladding layer and the fiber core in a lining tube in sequence, contracting and burning to obtain an optical fiber perform, and doping the cladding layer before depositing the fiber core to obtain the annular stress region, which is in contact or not in contact with the fiber core; step 2, and adopting the optical fiber perform for manufacturing the twisted optical fiber. By introducing the annular stress region, the adaptability of the twisted optical fiber to environmental stress is increased, and the manufacturing method thereof is simple and reliable.

A supermode optical fiber for transmitting orbital angular momentum, including a central solid cylinder, an inner solid ring, high refractive index columns distributed on the solid ring and an outer solid ring, an inner solid ring and a high refractive index column The ring core region, the central solid cylinder constitutes the inner cladding region, and the outer solid ring constitutes the outer cladding. Each mode coupling unit is single-mode transmission when the wavelength is greater than 1.2 μm. At the same time, the material of the central solid cylinder and the outer solid ring is the same and the refractive index is lower than that of the inner solid ring. The outer boundary of the central solid cylinder is the same as the inner solid ring. The inner boundary, the inner boundary of the outer solid ring and the outer boundary of the inner solid ring form a closed boundary with a refractive index gradient. The number of practically applicable modes of the present invention is equal to the number of theoretical modes, the ratio of the mode area to the area of ​​the ring core is high, and the solid structure is adopted, the design and drawing are simple, and it can be applied to long-distance high-power orbital angular momentum transmission, and can industrialization.

The present invention provides an anti-resonant hollow-core optical fiber. The optical fiber is composed of a first-type dielectric tube, a second-type dielectric tube and a first-type dielectric layer, including a high-refractive-index cladding region and a low-refractive-index core region. Both the first-type medium pipe and the first-type medium layer are connected to the second-type medium pipe. The area surrounded by the outer wall of the first-type dielectric tube close to the core region is the fiber core area (the first-type hole). A second-type hole is isolated between the first-type medium pipe and the first-type medium layer, and a third-type hole is isolated between the first-type medium pipe and the second-type medium pipe. The fiber core has a negative curvature boundary, the fiber has multiple anti-resonant layers, and the fiber cladding has no nodes, which effectively reduces the leakage loss, and the fiber has no loss peaks caused by lateral nodes, which increases the transmission bandwidth. In addition, the fiber modes are mainly distributed in air holes, which can effectively reduce the material absorption loss of the fiber, increase the damage threshold of the fiber, and effectively transmit high-power laser and terahertz waves.

A negative curvature of the empty core with high dual -refractive low loss, a photonic crystal fiber, including the cross -section of the fiber tube with a circular and internal empty core, the tube wall of the fiber tube includes two layers of ring structure, the fiber tube body body, the fiber tube bodyThere are two large hair tubes that are cut into the fiber -fiber expansion in the left and right symmetry in the empty core, and the two large fiber tubes are set up between the upper and lower fiber tubes below and below.In the small capillary tube, both large capillary tubes are set in a medium -capped tube that is cut into the large capillary tube. Small hairy tubes, medium hair thin tubes, and large hair fine tubes are symmetrical.The optical wave transmission of the cavity, fiber tube, large capillary tubes, medium capillary tubes, and small capillary tubes are made of silicon glass.This optical fiber structure is simple, and the capacity of the capillary structure can be adjusted in a large range, which is conducive to the realization of HCF industrial preparation and commercial applications.

The invention discloses a high double-refraction chromatic dispersion adjustable pohotonic crystal fiber. The high double-refraction chromatic dispersion adjustable pohotonic crystal fiber comprises a substrate material, a fiber core, rectangular arranged medium holes and regular triangle lattice arranged medium holes, wherein the fiber core, the rectangular arranged medium holes and the regular triangle lattice arranged medium holes are distributed from inside to outside, a center that defines an end face of the optical fiber serves as a circle center, an X axis is parallel to long side directions of a rectangle that the rectangular arranged medium holes correspond to, a Y axis is parallel to short side directions of the rectangle that the rectangular arranged medium holes correspond to, the X axis and the Y axis pass through the circle center, the fiber core, the rectangular arranged medium holes and the regular triangle lattice arranged medium holes are symmetrical along the circle center respectively, five medium holes are designed in the long sides of the rectangle, three medium holes are designed in the short sides of the rectangle, and positions which are adjacent to second and fourth medium holes of the long sides of the rectangle in the Y axis direction are free of medium holes in terms of the regular triangle lattice arranged medium holes. The high double-refraction chromatic dispersion adjustable pohotonic crystal fiber has the advantages of high double refractions and low confinement loss, and hole intervals and medium hole sizes can be adjusted so that adjustment of large negative dispersion and zero dispersion wave lengths can be achieved.

The invention discloses a photonic crystal fiber capable of transmitting 22 photon angular momentum modes. The photonic crystal fiber comprises a center fiber core, an annular high refractive index layer and an annular cladding, wherein the fiber core is a large air hole; the annular cladding comprises a cladding I, a cladding II, a cladding III and a cladding IV; the cladding I is composed of 36 square air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of a cross section of the optical fiber is 10 degrees; the cladding II is composed of 30 circular air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of the cross section of the optical fiber is 12 degrees; the cladding III is composed of 36 circular air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of the cross section of the optial fiber is 10 degrees; and the cladding IV is composed of 40 circular air holes in a circular uniform arrangement manner. According to the photonic crystal fiber disclosed by the invention, the quantity of OAM (Orbital Angular Momentum) modes supported by a waveband of 1500-1600nm reaches 22, crosstalk among the various modes is less, confinement loss of most of the modes is low (10<7>dB / m), and the photonic crystal fiber is small in dispersion and low in nonlinear coefficient.

The invention discloses a nested type hollow-core anti-resonance optical fiber with a crescent-shaped cladding. The nested type hollow-core anti-resonance optical fiber comprises an optical fiber outer sleeve, a circular nested cladding tube, crescent-shaped outer cladding tubes and an air fiber core from outside to inside in sequence; the circular embedded cladding tube and the crescent-shaped outer cladding tubes meet the anti-resonance reflection waveguide (ARROW) principle in design and are specifically made of silicon dioxide, and the thickness of the circular embedded cladding tube and the crescent outer cladding tubes is t; in the cladding region, a plurality of crescent cladding tubes with circular embedded sleeves are arranged at certain intervals in a surrounding manner to form the cladding region, and a central region surrounded by the boundary of the crescent cladding tubes is an air fiber core region.

The invention discloses a negative-curvature terahertz optical fiber supporting 52 kinds of orbital angular momentum modes, which includes a polymer cladding layer, an outer elliptical cladding tube region, an annular cladding tube, an inner elliptical cladding tube region, a fiber core area. The outer elliptical cladding tube region is composed of 12 annularly arranged polymer unit structures; the inner elliptical cladding tube region is composed of 18 circularly arranged polymer unit structures; the inner elliptical cladding unit structure and the outer elliptical cladding The layer unit structure is respectively connected with the annular cladding tube unit structure to form the cladding tube area of ​​the optical fiber structure. The invention can generate orbital angular momentum (OAM) mode with relatively high purity, and can form multiple channels during communication in the annular area. The invention applies the orbital angular momentum multiplexing technology to the terahertz wave communication, improves the channel capacity of the communication system, and at the same time makes the information have higher security in the transmission process, and has the advantages of low loss, large communication capacity and the like.

The invention discloses a single-polarization single-mode photonic crystal fiber with high nonlinearity. The cross section of the photonic crystal fiber comprises a fiber core and a cladding. The-cladding is a peripheral region which is the same as the normal photonic crystal fiber and is formed by evenly distributed air holes (2) with the same structure. The fiber core is composed of a substrate material (1) which is arranged on the center of the optical fiber end face as well as four high-ellipticity air holes (3) which are closely arranged, not mutually overlapped and in rectangular distribution. In the photonic crystal fiber, a cut off characteristic of two polarization modes of a basic mode can be adjusted by finely adjusting distance between centers of air holes, which causes one of the polarization modes to be cut off in the applied waveband, thus realizing the wide-bandwidth single polarization transmission. Meanwhile, the air holes (3) suppress the generation of high order mode, which allows the cladding to use a higher air filling rate on the premise of not changing the single-mode transmission characteristic of the optical fiber, therefore the mode area and the confinement loss are reduced. The single-polarization single-mode photonic crystal fiber with the high nonlinearity solves the problem that the high nonlinearity, low confinement loss and wide band single-polarization single-mode characteristic can not be realized at the same time in the existing photonic crystal fiber technology.