114 results about "Relative refractive index" patented technology

A polarization-maintaining fiber (1) comprises a core (11), an inner layer (12) which surrounds the core (11) without a gap, a pair of stress-applying parts (13) which are disposed at positions such that the core (11) is sandwiched therebetween, and cladding (14) in which the inner layer (12) and the pair of stress-applying parts (13) are embedded, wherein: when light having a wavelength of 1.55 μm propagates through the core (11), the mode field diameter of the light is not more than 9.3 μm; when the length of said fiber is 0.25 m and said fiber is wound once around a mandrel having a radius of 2 mm such that the slow axes of the stress-applying parts (13) are perpendicular to a surface of the mandrel, a cutoff wavelength is not less than 1.32 μm; and the product of the area of a cross section of the inner layer (12) which is perpendicular to the lengthwise direction and the average relative refractive index difference of the entire inner layer (12) with respect to the cladding (14) is -36 to 0%μm2 <sp / >.

An MCF includes a plurality of cores each extending in a direction along a central axis and a cladding covering each of the plurality of cores. The cladding includes a low refractive index barrier. The low refractive index barrier includes an alkali metal element. A relative refractive index of the low refractive index barrier is lower than an average value of a relative refractive indices of the cladding overall. The core interval is set such that a total sum of the power coupling coefficients between a specific core among the plurality of cores and each of all remaining cores is 2.3×10−4 / km or less.

The invention provides a small-diameter low-loss optical fiber, and relates to the technical field of optical communication. The small-diameter low-loss optical fiber comprises a core layer, and the value range of the relative refractive index difference delta n1 of the core layer is 0.35%-0.65%. The wrapping layer wraps the outer side of the core layer; wherein the cladding comprises a first platform layer wrapping the core layer, the relative refractive index difference of the first platform layer is # imgabs0 #, r1 is the radius of the core layer, r2 is the radius of the first platform layer, delta n2 is the relative refractive index difference of the inner surface of the first platform layer, and delta n3 is the relative refractive index difference of the outer surface of the first platform layer; the first platform layer is wrapped with the sunken layer, and the numerical value range of the relative refractive index difference delta n4 of the sunken layer is-0.4%-0.6%. According to the small-diameter low-loss optical fiber provided by the invention, the strength of the optical fiber is remarkably improved and the overall performance of the optical fiber is optimized under the condition that the small size is maintained.

A method for determining a state of a cell, the cell being placed in a sample in contact with a culture medium, includes illuminating the sample with a light source and acquiring an image of the sample with an image sensor, the image sensor lying in a detection plane. From the acquired image, a position of the cell in a plane parallel to the detection plane is located and a refractive index or a relative refractive index of the cell is estimated, the relative refractive index corresponding to a refractive index of the cell relative to the refractive index of the culture medium. From the estimation, an index of interest of the cell is determined. From the index, a state of the cell among predetermined states is classified, the predetermined states including at least one apoptosis state and one living state.

This multicore fiber (100) comprises: a plurality of center core parts (111, 112); a plurality of low refractive index layers (131, 132) that surround the outer circumference of each of the center core parts; and a cladding part (140) that surrounds the plurality of low refractive index layers. The maximum refractive index of the center core parts is higher than the average refractive index of the cladding part. The minimum refractive index of the low refractive index layers is lower than the average refractive index of the cladding part. Among the plurality of center core parts, the absolute value of the difference in the relative refractive index difference of the maximum refractive index of the center core parts with respect to the average refractive index of the cladding part, and the absolute value of the difference in the center core diameters are 10% or less. In two low refractive index layers among the plurality of low refractive index layers, the absolute value of the difference in the relative refractive index of the minimum refractive index of the low refractive index layers with respect to the average refractive index of the cladding part, or the absolute value of the difference in the ratio of the outer diameters of the low refractive index layers with respect to the center core diameters is 10% or more.

The invention discloses a dual-channel all-optical switch device based on two-dimensional Bi2O2Se and a design method of the dual-channel all-optical switch device. The core of the device is an optical interference structure formed by two-dimensional Bi2O2Se nanosheets arranged on a mica substrate. The same group of transient absorption spectrum data is obtained through a pumping-detection system, and is decoupled into two independent switching channels: a channel I is based on carrier relaxation dynamics, and switching is realized by detecting a ground state bleaching signal at a wave band of 560-670 nm; the channel II is based on refractive index modulation caused by a Kramers-Kronig relationship, and realizes switching by analyzing interference fringe signals formed by probe light between the upper surface of the nanosheet and the lower surface of the mica substrate. The invention also provides a quantitative design method of the device, and the method achieves the fitting of an interference fringe signal through building a transient refractive index model, and precisely solves the relative refractive index change dynamics. The dual-channel device realizes picosecond-level ultrafast response (the channel I is 38.1 ps, and the channel II is 65.8 ps) and low-power-consumption operation (mJ / cm < 2 > magnitude), and the channel switch ratios respectively reach 1.74 and 1.93.

The invention relates to a broadband bending-resistant multimode optical fiber and a preparation method thereof, the refractive index profile of a core layer is in a gradually-changed parabola shape, the distribution index alpha is 1.95-2.65, the radius R1 of the core layer is 12-35 microns, the delta 1max is 0.9%-1.4%, the relative refractive index difference delta 1min at the R1 position of the edge of the core layer is-0.16%--0.06%, cladding layers comprise an inner cladding layer, a first sunken cladding layer, a second sunken cladding layer and an outer cladding layer from inside to outside in sequence, the inner cladding layer is sequentially provided with a first inner cladding layer and a second inner cladding layer from inside to outside, the single-side width (R4-R3) of the first sunken cladding layer is 1.5-9.0 [mu] m, delta 4 is-1.1%--0.60%, the single-side width (R5-R4) of the second sunken cladding layer is 1.0-3.0 [mu] m, delta 5 is-1.0%--0.55%, the radius R6 of the outer cladding layer is 60-65 [mu] m, and delta 6 is-0.12-0.12%. The core cladding is reasonable in structural design, has the excellent characteristics of high bandwidth, strong bending resistance and low attenuation, and is high in transmission efficiency and excellent in long-term stability and reliability.

A multicore optical fiber may include a common cladding comprising a radius R4 defining a glass portion of the optical fiber and having a cladding relative refractive index Δ4. At least two waveguides may extend through the common cladding. Each waveguide may include a core region, an inner cladding region, and a depressed cladding region. Each core region may include a maximum relative refractive index Δ1max. Each inner cladding region may include a relative refractive index Δ2. Each depressed cladding region may include a minimum relative refractive index Δ3min and a trench volume from 20-45%µm2 such that Δ1max>Δ2>Δ3min, and Δ4>Δ3min. A cable cutoff wavelength of each waveguide is ≤1150 nm. The co-propagating and counter-propagating inter-waveguide cross talk between each waveguide and a nearest waveguide is <-35 dB at 1310 nm and <-20 dB at 1550 nm for application lengths of 20 m. A mode field diameter of each waveguide is 8.2-9.0 µm at 1310 nm.

The application discloses a bending-insensitive high-bandwidth multi-mode optical fiber, which comprises a core layer, an extension layer, an inner cladding layer, a sunken cladding layer and an outer cladding layer arranged in sequence from inside to outside, the refractive index profile of the core layer is parabolic, the distribution index is 1.9-2.2, the maximum relative refractive index difference of the core layer center position is 0.9%-1.2%, the relative refractive index difference of the extension layer is -0.03% to -0.02%, the difference between the highest relative refractive index difference and the lowest relative refractive index difference of the inner cladding layer is 0.005%-0.03%, the single-side radial width of the inner cladding layer is 0.5-4 mu m, the single-side radial width of the sunken cladding layer is 3-9 mu m, and the relative refractive index difference of the sunken cladding layer is -0.7% to -0.4%. In the application, the optical fiber viscosity is optimized, the sensitivity of the optical fiber bandwidth to wavelength is reduced, the optical fiber has good bending resistance and super high bandwidth performance by reasonably designing the waveguide structure and the doping system.

A polarization maintaining optical fiber (1) has: a core (11); an inner layer (12) that surrounds the core (11) without a gap; a pair of stress applying portions (13) disposed at positions sandwiching the core (11); and a cladding (14) that encloses the inner layer (12) and the pair of stress applying portions (13), a mode field diameter of light of a wavelength of 1.55 μm is 9.3 μm or less in a case where the light propagates in the core (11), a cutoff wavelength is 1.32 μm or more in a case where the optical fiber length is 0.25 m and the stress applying portions (13) are wound one turn around an axis having a radius of 2 mm in a manner that a slow axis of the stress applying portions (13) is perpendicular to a surface of the axis, and a product of an area of a cross section of the inner layer (12) perpendicular to a length direction and an average of relative refractive index differences of the inner layer (12) as a whole with respect to the cladding (14) is -36% μm 2 or more and 0% μm 2 or less.

The object of this invention is to obtain, at a lower cost, an optical glass with a low temperature coefficient of relative refractive index that helps correct the effects of temperature changes on imaging characteristics, and preforms and optical elements using this optical glass. The optical glass, by mass%, contains 1.0% to 27.0% SiO2, 5.0% to 34.0% Ln2O3 (where Ln is one or more selected from the group consisting of La, Gd, Y, and Yb), more than 30.0% to 65.0% BaO, and 25.0% or less B2O3. The temperature coefficient of its relative refractive index (589.29 nm) (40–60 °C) is in the range of +3.0 × 10⁻⁶ to -10.0 × 10⁻⁶ (°C⁻¹).

This disclosure relates to optical integrated devices, optical integrated circuit wafers, and methods for manufacturing optical integrated devices. The optical integrated device includes a substrate and a waveguide having a hollow structure. The waveguide includes a first waveguide and a second waveguide, the second waveguide being optically coupled to the first waveguide and having a relative refractive index difference smaller than that of the first waveguide, and the waveguide converting a mode diameter to the mode diameter of an optical fiber according to the propagation of light. The optical integrated device includes a recessed portion formed near a cleavage line on the substrate, such that, with the cleavage end surface of the substrate protruding further in the axial direction of the optical waveguide than the output end surface of the second waveguide, the width of the output end surface is smaller than the core width of the optical fiber optically coupled to the output end surface.

The optical fiber type light spot homogenizer comprises a machine frame, a laser source is arranged at one end of the machine frame, a multimode optical fiber corresponding to the laser source is arranged at the other end of the machine frame, the laser source emits a laser beam, the multimode optical fiber receives the laser beam, and the multimode optical fiber is connected with the machine frame. The multi-mode fiber laser is characterized in that the relative refractive index difference section of the inner side of the sunken inner cladding of the multi-mode fiber is in a two-stage step decreasing shape, and the center line of the laser beam and the center of the end face of the multi-mode fiber are aligned and offset in parallel by a section of radial offset. The device is small in size, low in cost, compact in structure, good in homogenization effect and stable in performance, and can be directly seamlessly integrated with an input laser source and an output optical fiber system. The optical fiber type light spot homogenizer assembly and the laser beam shaping system can achieve efficient light spot homogenization within the centimeter-level distance. The system can be applied to a vehicle-mounted laser radar, a vehicle-mounted head-up display, a multimode PON optical splitter, laser medical equipment or laser material processing equipment and the like.

This invention belongs to the field of optical fiber communication technology and discloses a low-refractive-index doped mother tube, a capillary, a preparation method, and applications. The invention first deposits a low-refractive-index doped silicon dioxide layer on the inner surface of a pure silicon dioxide liner to prepare a low-refractive-index doped mother tube. Then, the low-refractive-index doped mother tube is heated to its softening temperature and drawn to obtain a low-refractive-index doped capillary. The minimum relative refractive index difference of the low-refractive-index doped silicon dioxide layer in this invention is -1.8% to -2.6%. The low-refractive-index doped capillary designed in this invention can be used to prepare optical fiber power combiners and can improve the performance of the combiners.

A low-loss bend-resistant single-mode optical fiber (10), comprising, from the center toward the outside, a core layer (11), a first inner cladding layer (12), a second inner cladding layer (13), a depressed cladding layer (14), and an outer cladding layer (15) which are sequentially arranged. The outer radius of the first inner cladding layer (12) is R2, the width R2-R1 of the first inner cladding layer (12) ranges from 1 μm to 4 μm, and a relative refractive index difference Δ2 between the first inner cladding layer (12) and the outer cladding layer (15) ranges from -0.2% to 0%; the outer radius of the second inner cladding layer (13) is R3, the width R3-R2 of the second inner cladding layer (13) ranges from 1 μm to 4 μm, and a relative refractive index difference Δ3 between the second inner cladding layer (13) and the outer cladding layer (15) ranges from -0.1% to 0.1%; and the first inner cladding layer (12) and the second inner cladding layer (13) which have different refractive indices are arranged between the core layer (11) and the depressed cladding layer (14). By adjusting the difference value of a refractive index difference between the first inner cladding layer (12) and the second inner cladding layer (13), a zero-dispersion wavelength shifts towards a long wavelength direction, and the slope of the zero-dispersion wavelength is reduced, achieving compatibility with G.652 dispersion standard requirements.

The present invention aims to provide a multi-core optical fiber and a design method thereof, which configures four cores of a single-peak type with a standard cladding diameter, satisfies a desired specification, and is excellent in mass productivity, quality, and yield. The multi-core optical fiber of the present invention has four cores of a single-peak type refractive index profile with a radius a arranged in a square lattice shape in a long side direction, and a cladding region with a diameter of 125 ± 1 μm, which has a lower refractive index than the cores, and an absolute value of a relative refractive index difference from the cores is Δ, on an outer peripheral portion of the cores, and the four cores are arranged in a manner that a relationship of a minimum distance (OCT) from a center of the core to an outer periphery of the cladding region, a minimum value Λ of a pitch of the cores, and an MFD at a wavelength of 1310 nm satisfy a number C1, and the relative refractive index difference Δ of the cores and the cladding region and the radius a of the cores are set. [Number C1] OCT ≥ 3.73 MFD + 3.43 Λ ≤ -5.28 MFD + 83.54.

This optical fiber comprises a core, an inner cladding, a trench, and an outer cladding. When the relative refractive index difference of the core is ∆1, the relative refractive index difference of the inner cladding is ∆2, the relative refractive index difference of the trench is ∆3, the relative refractive index difference of the outer cladding is ∆4, the outer diameter of the core is 2r1, the outer diameter of the inner cladding is 2r2, the outer diameter of the trench is 2r3, and the outer diameter of the outer cladding is 2r4, the following relationships are established.　2.2 ≤ r2 / r1 ≤ 3.6; 3μm ≤ r3 － r2 ≤ 12μm; 0.25% ≤ ∆1 － ∆2 ≤ 0.50%; − 0.70% ≤ ∆3 ≤ − 0.10%; A zero-dispersion wavelength is 1296-1306 nm. A zero-dispersion slope is 0.088 ps / nm2 / km or less. A 500-meter cable cutoff wavelength is 1260 nm or less. A bending loss for light with a wavelength of 1310 nm when the optical fiber is wound around a mandrel having a diameter of 15 mm is 0.5 dB or less per turn.

The application discloses a silica ceramic core and a preparation method thereof. The preparation method of the silica ceramic core comprises the following steps: preparing a ceramic slurry, wherein the ceramic slurry comprises ceramic particles, and the ceramic particles comprise silica and silicon nitride; preparing a ceramic matrix blank by means of light-curing 3D printing based on the ceramic slurry; pre-sintering the ceramic matrix blank to obtain a ceramic matrix; preparing an additive solution, impregnating the additive solution into the ceramic matrix, and then performing a heating reaction; and then performing sintering to obtain the silica ceramic core. The application solves the problem of easy scattering caused by the low relative refractive index of the ceramic slurry in the process of preparing the silica ceramic core by means of light-curing 3D printing of the silica ceramic, thereby avoiding the decrease of the forming precision, and the silica ceramic core is easy to demold, and the problem of the rough surface of a casted part caused by the high porosity of the ceramic core during casting is avoided.

An object of the present invention is to achieve a low delay core applicable to a Master channel of a Master-Slave CPE (MS-CPE) transmission method with a general-purpose refractive index distribution structure.An optical fiber according to the present invention is a single-mode optical fiber, and has an SI-type refractive index distribution structure, in which a clad region relative refractive index difference Δ (%) with respect to a core region refractive index, a radius a (μm) of the core region, and a group delay time difference Δτ between the Master channel and the Slave channel satisfy “Mathematical Expression 19” and “Mathematical Expression 20”, orhas a W-type refractive index distribution structure, in which a mode field diameter MFD is 9.5 to 10.1 μm, and a relative refractive index difference Δ1 (%) of a low refractive index layer with respect to a core, a relative refractive index difference Δ2 (%) of the clad region with respect to the core, the core radius a1, and the group delay time difference Δτ between the Master channel and the Slave channel satisfy “Mathematical Expression 41”.

A lateral light input / output circuit (10) comprises: a grating part (20) including a grating (21) formed on a core (11) of an optical fiber (13); and a tap part (30) including a tap waveguide (31) branched from the core (11). The relative refractive index difference of the optical fiber (13) and the radius of the core are set to values at which the full width at half maximum of light passing through the grating (21) is 20 nm or less.

A metamaterial (10) is a terahertz wave control element that optically controls terahertz waves, and has a matrix (20) and a plurality of dielectric fine particles (30) dispersed in the matrix (20). The size of the dielectric fine particles (30) is less than or equal to the wavelength of terahertz waves. The value of the relative refractive index of the matrix (20) for terahertz waves is smaller, by 2.0 or more, than the value of the relative refractive index of the dielectric fine particles (30) for terahertz waves.

The invention relates to a low-attenuation non-zero dispersion shift single-mode fiber and application, the low-attenuation non-zero dispersion shift single-mode fiber comprises a first core layer, a second core layer, a third core layer, a sunken cladding, an auxiliary cladding and a first outer cladding, the radius R1 of the first core layer is 0.8-1.3 [mu] m, the relative refractive index difference 1 is-0.01%-0.05%, the radius R2 of the second core layer is 1.5-1.8 [mu] m, the relative refractive index difference 2 is-0.12%-0.15%, the radius R3 of the third core layer is 2.0-2.5 [mu] m, and the radius R2 of the third core layer is 0.5-1.5 [mu] m. The radius R4 of the sunken cladding layer is 5-6.5 microns, the relative refractive index difference 3 is-0.34% to-0.30%, the radius R4 of the sunken cladding layer is 5-6.5 microns, and the relative refractive index difference delta 4 is-0.51% to-0.57%. The core layer of the optical fiber is of a three-core-layer structure, the interlayer stress is reduced when the optical fiber is drawn, and the relative refractive index difference of the core layer is close to 0, so that the distortion of the core layer can be reduced, and the attenuation of the optical fiber is reduced.

The application relates to a high-bandwidth bending-insensitive multi-mode optical fiber which can be used for data communication and automobile communication, comprising a core layer and a cladding layer, the core layer has a parabolic refractive index profile, and the cladding layer comprises a first inner cladding layer, a second inner cladding layer, a sunken cladding layer and an outer cladding layer from inside to outside; the core layer distribution index alpha1 is 1.9-2.1, the core layer radius R1 is 12-28 mu m, the core layer center maximum relative refractive index difference Delta0 is 0.8%-1.2%, the relative refractive index difference Delta1 at the core layer edge R1 is-0.03%-0.03%, the width (R2-R1) of the first inner cladding layer is 0.4-3 mu m, the relative refractive index difference Delta2 at the outer side edge of the first inner cladding layer is-0.3%--0.04%, and the first inner cladding layer refractive index profile is a power exponential function distribution, and the width (R3-R2) of the second inner cladding layer is 0.5-4 mu m. The application realizes the optimization of optical transmission bandwidth performance.

The application relates to a method and device for measuring the relative refractive index difference between a fiber core and a cladding. The method comprises: inputting single transverse mode laser beams of different wavelengths in a target application wave band into a fiber to be measured at equal wavelength intervals, obtaining a light spot pattern of the fiber to be measured at each wavelength, and then obtaining a two-dimensional measurement matrix with the row and column sizes being the number of pixel points of the light spot pattern and the number of sampling wavelengths; performing Fourier transform on each row of data of the two-dimensional measurement matrix and adding the results to obtain a differential mode group delay test value of a first high-order mode relative to a base mode; and searching a lookup table of the change of a differential mode group delay theoretical value corresponding to a high-order mode of the fiber to be measured with the core-cladding refractive index difference to find a differential mode group delay theoretical value closest to the differential group delay test value under the core diameter of the fiber to be measured, and obtaining the core-cladding refractive index difference of the fiber to be measured. The method can realize efficient, accurate and non-invasive measurement of the core-cladding refractive index difference of a long link fiber.

The present invention relates to the field of gain optical fibers, and in particular to a graded-index optical fiber in which pump absorption and core numerical aperture are negatively correlated along the axial direction, and a preparation method thereof. The graded-index optical fiber in which pump absorption and core numerical aperture are negatively correlated along the axial direction comprises a core layer, a step layer, a cladding layer, and a coating layer arranged in sequence from the inside to the outside in the radial direction, wherein the refractive index n1 of the core layer is greater than the refractive index n2 of the step layer, the refractive index n3 of the cladding layer is greater than the refractive index of the coating layer, the refractive index n1 of the core layer has a gradual trend along the axial direction, the refractive index n2 of the step layer has a gradual trend along the axial direction, and the rate of change of n2-n3 along the axial direction is greater than the rate of change of n1-n3 along the axial direction. The present invention achieves a gradual increase in pump absorption along the axial direction and a gradual decrease in core numerical aperture along the axial direction by controlling the rate of change of the relative refractive index (n2-n3) of the console layer along the axial direction to be greater than the rate of change of the relative refractive index (n1-n3) of the core layer along the axial direction.

The invention belongs to the technical field of few-mode optical fibers, and discloses an ultralow differential mode group delay few-mode optical fiber and a preparation method thereof. The ultralow differential mode group delay few-mode optical fiber provided by the invention comprises a core layer structure, an inner cladding layer structure and an outer cladding layer from inside to outside, the core layer structure comprises a first core layer and a second core layer from inside to outside; the two core layers are provided with gradient sections, the distribution index alpha 1 of the first core layer is 1.5-1.9, and the distribution index alpha 2 of the second core layer is 1.4-1.9; the minimum relative refractive index difference 1 of the first core layer is 0.3% to 0.6%; the maximum relative refractive index difference of the first core layer and the maximum relative refractive index difference of the second core layer are the same and marked as 2, 2 is 0.6%-0.9%, and 2 > 1; the second core layer has a minimum relative refractive index difference 3 of-0.2% to-0.1%. According to the invention, extremely low differential mode group delay can be realized.

The invention relates to a high-nonlinearity photonic crystal fiber and an optical fiber amplifier, the fiber comprises a core layer and cladding layers, the cladding layers comprise an inner cladding layer and an outer cladding layer, the high-nonlinearity photonic crystal fiber is characterized in that the refractive index profile of the core layer is in alpha power exponential function distribution, the distribution index alpha of the core layer is 2.0-8.0, the radius a of the core layer is 0.8-2 microns, and the refractive index alpha of the core layer is 2.0-8.0. The maximum relative refractive index difference delta 1max is 2-5%, the inner cladding layer is an air hole dot matrix inner cladding layer, the outer cladding layer is arranged outside the inner cladding layer, and the outer cladding layer is a pure silicon dioxide glass outer cladding layer. According to the invention, the large refractive index difference between the high refractive index core layer and the low refractive index air hole cladding is beneficial to improving the binding ability of the fiber core to light on one hand and promoting the reduction of the effective mode field area of the optical fiber on the other hand, thereby improving the nonlinear performance. The gradient high-nonlinearity photonic crystal fiber provided by the invention is mainly used in the field of communication and can be used as an optical gain medium of an optical fiber amplifier, and a corresponding device has the advantages of low noise, high gain and the like.

To provide an optical fiber that is suitable for reducing transmission loss and is highly manufacturable. [Solution] The optical fiber comprises a core made of silica glass and a cladding portion made of silica glass, surrounding the outer circumference of the core and having a refractive index lower than the maximum refractive index of the core. The core has a center core which has the highest average refractive index within the optical fiber, and the center core does not contain germanium as a dopant to increase the refractive index of the silica glass, and the relative refractive index difference Δclad between the refractive index of the cladding portion and the refractive index of the pure silica glass is 0% or more.

The application relates to a non-zero dispersion-shifted single-mode optical fiber with a low cutoff wavelength and a low macro-bending loss and an application, which comprises a core layer and a cladding layer surrounding the core layer, the cladding layer comprises a depression layer, an inner cladding layer and an outer cladding layer arranged in sequence from inside to outside, the inner cladding layer comprises a first inner cladding layer and a second inner cladding layer arranged in sequence from inside to outside, the relative refractive index difference Delta 1 of the core layer is 0.500% to 0.570%, and the refractive index curve of the core layer is a gradually decreasing parabolic shape, and the refractive index decreases with the increase of the core diameter. The shape of the refractive index profile of the optical fiber is adjusted, the conventional multi-core layer step type design is avoided, the gradually decreasing parabolic design is adopted, compared with the triangular depression core structure, the core center high refractive index range and the effective refractive index area of the application are larger, the waveguide of the light can be effectively bound in the core, and compared with the trapezoidal core, the core layer decreases in a parabolic mode with the radius, the radius of the core layer can be effectively reduced, and the purposes of reducing the cutoff wavelength and the bending loss are achieved.

A multimode optical fiber having a core region. The core region includes silica, has an outer radius r1, and has a maximum relative refractive index of about 1.5% or less. Further, the multimode optical fiber is configured to have an effective bandwidth of about 4.7 GHz-Km or more for an excited portion of the core region having a diameter greater than 50 microns, the effective bandwidth being at a wavelength in a range of about 800 to about 1370 nm.