CN103246010A

CN103246010A - Optical fiber with multiple refractive indexes

Info

Publication number: CN103246010A
Application number: CN2013101689905A
Authority: CN
Inventors: 贺作为; 张良; 汪洪海; 袁健; 陈明; 郭浩林
Original assignee: Jiangsu Hengtong Optic Electric Co Ltd
Current assignee: Hengtong Optic Electric Co Ltd
Priority date: 2013-05-09
Filing date: 2013-05-09
Publication date: 2013-08-14
Anticipated expiration: 2033-05-09
Also published as: CN103246010B

Abstract

The invention discloses an optical fiber with multiple refractive indexes, which comprises a fiber core, an inner wrapping layer and an outer wrapping layer, wherein the inner wrapping layer and the outer wrapping layer are wrapped on the fiber core from the inside to the outside in sequence; the refractive index of the fiber core, the inner wrapping layer and the outer wrapping layer are n1, n2 and n3 respectively; wherein the refractive index Delta 1 equals to the difference of n1 and n2/n1, and approximately equals to 0.28 percent to 0.32 percent; and Delta 2 equals to the difference of n2 and n3/n2 and approximately equals to 0.1 below zero percent to 0.3 below zero percent. According to the optical fiber provided by the invention, VAD (Virtual Address Descriptor) method is adopted to produce optical fiber with a certain refractive index n1, the inner wrapping layer of the optical fiber adopts a fluoride doped glass tube preformed with a low refractive index n2, and the outer wrapping layer of the optical fiber adopts a glass tube preformed with a low refractive index n3, so that the doping amount of Ge of different index is decreased when compared with fibre core, the absorbing of light by the fibre core is decreased, and the luminous power is basically kept in the fibre core; and as Delta 1 equals to the difference of n1 and n2/n1 and approximately equals to 0.32 percent, the light can not be transmitted in the inner wrapping layer, so that the wastage of the fiber optic is greatly decreased.

Description

A kind of optical fiber with a plurality of refractive indexes

Technical field

The present invention relates to a kind of optical fiber, be specifically related to a kind of optical fiber with a plurality of refractive indexes, belong to the optical fiber technology field.

Background technology

Fibre loss is the bottleneck of limit fibre communication repeating distance, in order to reduce in the telecommunication optical fiber because loss agency's restriction, common way is to increase fiber amplifier in relaying, this quadrat method can solve the problem that loss brings greatly to a certain extent, but under the situation of some link condition restriction, for example to set up the relay station difficulty big in area such as sea, desert, and cost is high again simultaneously, just brings very big challenge.

Common fibre loss 1550nm window is about 0.2dB/km, repeater span generally is no more than 80km, and low loss fiber 1550nm window is approximately less than 0.18dB/km, repeater span can surpass 120km, adopt low loss fiber can on communication line, significantly reduce the construction of relay station, make that client's final cost is effectively reduced.In addition, existing fibre loss is bigger.

Summary of the invention

At the deficiency that prior art exists, the object of the invention provides a kind of low-loss optical fiber with a plurality of refractive indexes.

To achieve these goals, the present invention realizes by the following technical solutions:

The present invention includes fibre core, inner cladding and surrounding layer, inner cladding and surrounding layer are wrapped on the fibre core from inside to outside successively; The refractive index of fibre core, inner cladding and surrounding layer is respectively n1, n2 and n3;

Wherein, refractive index 1=n1-n2/n1 ≈ 0.28%～0.32%;

Wherein, refractive index 2=n2-n3/n2 ≈-0.1%～-0.3%.

The a spot of germanium of doping in the above-mentioned fibre core (1), inner cladding is the glass tube of doping small amount of fluorine, surrounding layer is the glass tube of pure silicon dioxide.

The diameter of above-mentioned fibre core is 6～10um, and the diameter of inner cladding is 10～20um.

The fibre core of optical fiber of the present invention uses the manufacturing of VAD method to have certain refractive index n 1, inner cladding adopt preformed have a low-refraction n2 mix the fluorine glass tube, surrounding layer partly is the lower n3 glass tube of preformed refractive index, the different fiber of comparing fibre core has reduced the doping of germanium, thereby has reduced the absorption of fibre core to light, and luminous power remains in the fibre core substantially, because Δ 1=n1-n2/n1 ≈ 0.32%, light can not run out of in the inner cladding and transmit, thereby the loss of optical fiber reduces greatly.

Description of drawings

Fig. 1 is optical fiber structure synoptic diagram of the present invention;

Fig. 2 is fibre profile refractive index structures figure of the present invention;

Fig. 3 is process chart of the present invention.

Embodiment

For technological means, creation characteristic that the present invention is realized, reach purpose and effect is easy to understand, below in conjunction with embodiment, further set forth the present invention.

Referring to Fig. 1, optical fiber of the present invention comprises fibre core 1, inner cladding 2 and surrounding layer 3, and inner cladding 2 and surrounding layer 3 are wrapped on the fibre core 1 from inside to outside successively; The refractive index of fibre core 1, inner cladding 2 and surrounding layer 3 is respectively n1, n2 and n3; Wherein, refractive index 1=n1-n2/n1 ≈ 0.28%～0.32%; Wherein, refractive index 2=n2-n3/n2 ≈-0.1%～-0.3%.

The a spot of germanium of doping in the fibre core 1, inner cladding 2 is the glass tube of doping small amount of fluorine, surrounding layer 3 is the glass tube of pure silicon dioxide.

The diameter of fibre core 1 is 6～10um, and the diameter of inner cladding 2 is 10～20um.

The present invention uses VAD and RIC method in conjunction with the method for producing low loss fiber.The fibre core 1 of optical fiber uses the manufacturing of VAD method to have certain refractive index n 1, inner cladding 2 parts adopt preformed have a low-refraction n2 mix the fluorine glass tube, surrounding layer 3 parts are the lower n3 glass tube of preformed refractive index.This method makes the complicated fluorine technology of mixing become simple relatively, the different fiber of comparing fibre core 1 has reduced the doping of germanium, thereby has reduced the absorption of sandwich layer part to light, and luminous power remains in the sandwich layer substantially, because Δ 1=n1-n2/n1 ≈ 0.32%, light can not run out of transmission in the inner cladding 2.The method is produced low loss fiber and has been simplified technology, and the requirement of equipment is reduced relatively, greatly reduces production cost.

Fibre loss is≤0.320dB/km to be≤0.185dB/km at 1310nm at 1550nm.Other parameters of optical fiber satisfy the G.652 requirement of optical fiber.The refractive index of optical fiber should be the step-refraction index structure.

Referring to Fig. 3, optical fiber manufacturing method of the present invention, fibre core 1 adopts VAD technology, makes the single sandwich layer of refractive index, and VAD process deposits efficient height, two-layer clad material all is prefabricated profiled, only need assemble, can draw low loss fiber by RIC technology, complicated technology is decomposed, simplified production technology, reduced cost.

Specifically comprise following step:

(A) by designing the refractive index of determining fibre core 1;

Know constituting of fibre loss by analysis: loss α=Rn/ λ 4+ α IR+ α IM+ α OH, wherein Rn is rayleigh scattering coefficient Rn=1+0.62 Δ Gerod+0.6 Δ F2rod+0.44 Δ Gerod* Δ F2rod, with the infrared absorption loss, OH absorption loss and stress are relevant in addition.Therefore can namely reduce n1 by reducing the germanium concentration in the fiber cores 1, but n1 reduces the biography luminous energy power that meeting increases optical fiber, so will manage so just can guarantee that at the refractive index n 2 that reduces inner cladding 2 Δ 1 does not have big change than ordinary optic fibre.For this reason the present invention precast in advance than pure silicon dioxide refractive index little mix the refractive index n 2 that the fluorine glass tube reduces covering, formed a depression at inner cladding 2 places like this.

Surrounding layer 3 adopts prefabricated pure SiO2 glass tube, refractive index herein forms a projection again, this projection is not carried out the transmission of luminous energy, referring to Fig. 2, n1 is fibre core 1 refractive index that reduces after mixing among Fig. 2, n2 is inner cladding 2 refractive indexes of fluorine of having mixed, and n3 is surrounding layer 3 refractive indexes that pure silicon dioxide constitutes.

(B) carry out the deposition of fibre core 1 with VAD technology, the loose media that deposits is carried out sintering successively, dehydration and vitrifacation are drawn to predetermined diameter again;

(C) inner cladding 2 is installed in the surrounding layer 3, seals the end face of an end, again fibre core 1 is installed in the inner cladding 2, fibre core 1 is fixed, namely finish the manufacturing of preform 4;

Wherein, inner cladding 2 is the glass tube of doping small amount of fluorine, and surrounding layer 3 is the glass tube of pure silicon dioxide;

(D) preform 4 that assembles is installed on the wire-drawer-tower, then preform 4 is sent to graphite fiber drawing furnace 5, heating graphite fiber drawing furnace 5, the optical fiber 6 that diameter is 0.125mm is pumped in preform 4 fusings;

(E) by caliper 7, cooling tube 8 is coated with inflammatory blepharoedema 9 to optical fiber 6 successively, and UV solidifies 10, arrives main draw-gear 11, has namely finished the manufacturing of whole optical fiber.

More than show and described ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in above-described embodiment and the instructions just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims

1. the optical fiber with a plurality of refractive indexes is characterized in that, comprises fibre core (1), inner cladding (2) and surrounding layer (3), and described inner cladding (2) and surrounding layer (3) are wrapped on the fibre core (1) from inside to outside successively;

The refractive index of described fibre core (1), inner cladding (2) and surrounding layer (3) is respectively n1, n2 and n3;

Wherein, refractive index 1=n1-n2/n1 ≈ 0.28%～0.32%;

Wherein, refractive index 2=n2-n3/n2 ≈-0.1%～-0.3%.

2. the optical fiber with a plurality of refractive indexes according to claim 1 is characterized in that, a spot of germanium that mixes in the described fibre core (1), and described inner cladding (2) is the glass tube of doping small amount of fluorine, described surrounding layer (3) is the glass tube of pure silicon dioxide.

3. the optical fiber with a plurality of refractive indexes according to claim 1 is characterized in that, the diameter of described fibre core (1) is 6～10um, and the diameter of described inner cladding (2) is 10～20um.