The fiber light guide

 

(57) Abstract:

Usage: fiber-optic communication lines. The inventive fiber light guide contains the core light guide layer located on the surface of the core and is made with a certain thickness and refractive index greater than the refractive index of the core, and a protective sheath, made in the form of spray on the light guide layer metal film with a thermal expansion coefficient equal to the ratio of the core material, or close to it. 3 Il.

The invention relates to optoelectronics, fiber optics and can be used for fiber optic communications, aviation, Astronautics and the national economy in the fields of electronics, medicine, engineering.

Known fiber optic cable [1] consisting of a core shell polymer and having a refractive index of the cladding is less than or equal to the refractive index of the core.

The disadvantage is the increased losses due to parasitic waves, going from a fiber, increased dispersion and narrow bandwidth, low strength, temperature resistance and immunity.

The closest analogousness core and the refractive index, a large refractive index core, a protective shell.

The disadvantage is the high loss of radiation due to scattering in the shell, low immunity from external noise, low mechanical strength and temperature resistance.

The aim of the invention is the increased immunity from external noise and increased mechanical strength, increased energy density transmitted through the light, no radiation losses due to scattering in the shell, high temperature resistance.

To accomplish the purpose on the surface of the core light guide layer is made of a thickness h, satisfying the condition

h=0,5 5 (0.5 N)0,5where is the wavelength of the radiation;

N the number of modes of the radiation propagating in the light guide layer, the protective sheath is made in the form of a sprayed on the light guide layer metal film with a thermal expansion coefficient equal to the ratio of the core material, or close to it.

In Fig. 1-3 there is shown a device.

Waveguide fiber consists of a core 1, the light guide layer 2, the protective sheath 3 of the deposited metal film.

Optic fiber works in the following way I, inside of the light guide layer 2 is the distribution of N mod radiation due to total reflection from the mirror surface of the metal cover 3 from the border region with a lower refractive index core, this fashion radiation is distributed by shell, external interference 7 escaped with metallic coating.

The rationale for the functioning of the light guide has the following form. The propagation of radiation in the optical fiber based on the ratio of indices of refraction of the medium of propagation of the radiation and the surrounding membranes. In the fiber analiziruetsya waveguide directional fashion or out of the shell radiative, radiative fashion.

In Fig. 3 shows schematically the location of the modes in the layered light guide structure. On a flat surface svetovidovi layer 2 receives the radiation angle of the light will be reflected from the end surface at an angle equal to the angle of incidence and refracted wave will fall into the waveguide layer at an angle of refractiontrelated to the angle of the refraction law:

sin =ninsin t.

The critical angle of incidence, more, leading to total internal reflection depends on sootnoshenie when nshnngthese angles are different, and respectively are:

ng=arc sin nn/nin;

sh=arc sin no/nin.

If the angle of incidence of the beam on the surface of the light guideinlessshasngtotal internal reflection does not occur on any surface of the waveguide layer. The light will be partially reflected from its upper border and partially refracted out into the covering layer or the surrounding area. Reflected from the upper boundary of the light going to the bottom surface of the partition, also partially reflected in the waveguide layer, and partially refracted into the core. When more asngand shthe beam caught in the waveguide layer, will experience internal reflection not only on the top but on the bottom surfaces (waveguide mode) and will be distributed through the waveguide. For education propagating in the waveguide layer of the light guide layer of the light wave, in addition to internal reflection should also make concerted phases: phase shifts accumulated after two reflections from the upper and lower surfaces of the waveguide layer, must be a multiple of 2n (if not, the waves interfere with each other so that extinguish themselves). The solution is Anna wavelength there is some minimum (critical) thickness hkrcorresponding to only one waveguide fashion

hkr= 0,25 (nlayer2-nt2)0,5if h is less than hkr, sewage light in the waveguide layer does not occur, with increasing h compared to hkrthe possibility of the existence of two, three, etc. of the waveguide modes. For communications tend to use single-mode fiber, because intermode dispersion is absent and the bandwidth reaches Gigahertz. The production of such fibers is very difficult and expensive, since traditionally used Central vein as fiber and it must be sufficiently thin (3-5 μm) for the passage of the waveguide fashion. In the proposed optical fiber radiation propagates in the light guide layer on the surface of the core by forming a layer with a higher refractive index. Use the effect of radiation propagation in a planar waveguide structure. The refractive index of the radiation is determined by the presence of free electrons in the medium, changing the concentration of the substance is possible to adjust the refractive index. This greatly simplifies the technology of manufacturing of such structures on the surface of the core, you can use the and so D. simultaneous shielding of radiation within the fiber, while in the usual case, the luminescence of some mod out. When the refraction of the radiation on the surface of the partition will be no loss due to penetration into the next shell. There is an increase in the transmitted power through the fiber, thus increasing the ratio of the input light guide: M=1+2r/h, where r is the radius of the core;

h the thickness of the luminous layer.

When the value r=50 μm, h=2 μm, then the gain, in comparison with traditional in 51 times. When increasing the energy transmitted through the light, maybe its liquid cooling due to the metallized coating. Metallic coating with good immunity creates a durable protective coating that allows the use of fiber in harsh, high temperature environment, the application of ferromagnetic coatings will effectively be shielded from magnetic fields. The coefficient of thermal volume expansion metallized coating is close to or equal to the coefficient of the core material and its proximity is determined by the interval of values of the difference of the coefficients of the core material and the light guide layer. Possible values of the difference determined by izvestiem the mechanical strength of the fiber.

The need and the actual creation of this fiber are confirmed by the increasing volume and speed of information exchange, increasing demands for noise immunity and decreasing resources strategic materials.

The fiber light guide, containing the core light guide layer located on the surface of the core and is made with a refractive index higher refractive index of the core, and a protective sheath, wherein the light guide layer is made with a thickness h which satisfies the condition

h = 0,5(0,5 N)0,5,

where the wavelength of the radiation;

N the number of modes of the radiation propagating in the light guide layer,

while the protective sheath is made in the form of a sprayed on the light guide layer metal film with a thermal expansion coefficient equal to the ratio of the core material, or close to it.

 

Same patents:

FIELD: optical and electronic industry; production of fiber optic components having electrooptical effect.

SUBSTANCE: the inventions are dealt with optical and electronic industry, and may be used for development engineering of transmitting systems and data processing, in which application of the fiber optic components with electrooptical effect is expedient. The fiber consists of a core, a light conducting shell, a light-absorbing shell containing light-absorbing elements and current-carrying electrodes. The method includes operations of a down-draw of separate glass rods from glasses fillets composing elements of a fiber, piling up a pack of a with the form of cross-section of a hexahedron or a square including piling of electrodes, afterstretching of preform and its pulling into a fiber with application of a polymeric coating. The invention allows to create a single-mode fiber with heightened electrooptical effect from the glasses having a Kerr constant by 1.5 order higher than one of a quartz glass, to produce fibers with the given structure of shells, cores and control electrodes at simplification of process of a drawing down of fibers.

EFFECT: the invention ensures creation of a single-mode fiber with heightened electrooptical effect, to produce fibers with the given structure of shells, cores and control electrodes, to simplify process of fibers drawing down.

13 cl, 9 dwg

FIELD: fiber-optics.

SUBSTANCE: fiber has core and cover. Fiber is made in such a way, that in case of change of radiuses of beds with different refraction coefficients, at least one optical property of core, for example, effective section of core Aeff and slant of dispersion curve, reach appropriate limit values in given range of deflections from base radius. Length of cut wave equals 1450 nm or less. Optical fibers have practically constant optical properties and allow to vary chromatic dispersion in certain limits.

EFFECT: higher efficiency.

2 cl, 14 dwg

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