CN103760631B - A kind of Ge-doped double-core photonic crystal fiber - Google Patents

Abstract

The invention discloses a kind of Ge-doped double-core photonic crystal fiber, include quartz body, quartz body center mixes the conglobate Ge-doped region I of germanium structure, quartz body is provided with multiple big airport, multiple big airports are evenly distributed on around Ge-doped region I, in quartz body, also bias mixes the conglobate Ge-doped region II of germanium structure, is additionally provided with multiple little airport in quartz body, and multiple little airports are evenly distributed on around Ge-doped region II.

Description

A kind of Ge-doped double-core photonic crystal fiber

Technical field

The present invention relates to field fiber, a kind of Ge-doped double-core photonic crystal fiber.

Background technology

In modern optical fiber telecommunications system, the loss of silica fibre is to limit transfer rate, transmission range and transmission One of key factor of capacity boost.

The loss of optical fiber is that the luminous power caused due to the reason such as absorbed, scattering reduces phenomenon.The damage of optical fiber Consumption make optical signal pulses in transmitting procedure gradually decay die down, cause optical fiber telecommunications system error code to increase, limit Make the distance of optical signal pulses repeaterless transmission.The loss factor of silica fibre has decreased to substantially it at present Theoretical boundary, the research without fiber manufacturing Material Field breaks through, under its loss value is difficult to further Fall.It is true that widely used image intensifer solves restricted problem is lost in modern optical fiber telecommunications system.At present Common image intensifer has semiconductor optical amplifier, parametric optical amplifier, all kinds of doping image intensifer and optical fiber to draw Graceful amplifier (Fiber Raman Amplifier, FRA) etc..Wherein, FRA due to have noise coefficient low, Gain band is flexible, can realize the many merits such as broadband amplification, it has also become modern wavelength-division multiplex (WDM) optical fiber One of Primary Component of communication system.

The physical basis of FRA work is stimulated Raman scattering (Stimulited Raman Scattering, SRS) Phenomenon.In general, in nonlinear optical medium, the high-octane laser of transmission will scatter, little by one Portions incident power transfers to the luminous power that another frequency moves down, and the knots modification of frequency is determined by the character of medium, This process is referred to as spontaneous Raman scattering.If the heavy pumping light of a weak signal light and a higher frequency exists simultaneously Transmitting in nonlinear optical medium, and the frequency of flashlight is within the Raman gain bandwidth of medium, then due to Raman scattering effect, weak signal light can obtain energy from heavy pumping light and be amplified, and this process is exactly SRS. If using optical fiber as nonlinear dielectric, it is possible to make FRA.

The mathematical model of FRA stable state can be attributed to power below coupled-differential equations:

$s\left(i\right)\frac{d{P}_j}{\mathrm{dz}}=\underset{v_i>v_j}{\mathrm{\Σ}}\frac{g_R(v_i-v_j)}{K_{\mathrm{eff}}{A}_{\mathrm{eff}}}{P}_i{P}_j-\underset{v_j>v_k}{\mathrm{\Σ}}\frac{v_j}{v_k}\frac{g_R(v_j-v_k)}{K_{\mathrm{eff}}{A}_{\mathrm{eff}}}{P}_j{P}_k-{\mathrm{\α}}_j{P}_j(j=\mathrm{1,2}...n)---\left(1\right)$

Wherein P_j、v_jAnd α_jPower, frequency and the attenuation quotient of Shij road light, n=n respectively_p+n_s, n_p And n_sIt is pump light and flashlight number, g respectively_R(v_i-v_j) it is the Raman gain coefficienct of fiber medium used, Z is the transmission direction of flashlight, A_effFor the effective core area of optical fiber, formula (2) define:

$A_{\mathrm{eff}}=\frac{{\∫\∫}_V{\mathrm{\ψ}}_p^2\mathrm{dxdy}{\∫\∫}_V{\mathrm{\ψ}}_s^2\mathrm{dxdy}}{{\∫\∫}_V{\mathrm{\ψ}}_p^2{\mathrm{\ψ}}_s^2\mathrm{dxdy}}---\left(2\right)$

Wherein ψ represents the mould field intensity distribution of light wave, and subscript p and s represent pump light and flashlight, integration respectively Subscript V of symbol represents the whole cross-sectional area that respective mode field is full of.γ_R=g_R/A_effIt is defined as Raman gain Efficiency, in general optical fiber, A_effVarying less with frequency of light wave, so γ_RAnd g_RShape basic Unanimously.S (j) is a sign flag, takes negative sign when taking positive sign, reverse transfer when jth road light forward transmits, K_effIt is polarization correlation factor, typically takes 2.0.

When FRA is applied in WDM fiber communication system, there is in wider service band preferable gain Spectrum flatness is to it basic demand, but due to drawing currently as the various optical fiber of FRA gain media Graceful gain efficiency coefficient is the most uneven, only can not make with single pumping source so understanding according to formula (1) and formula (2) Conventional FRA has smooth gain spectral in wider wave band.Traditional all kinds of fiber manufacturing FRA are utilized to there is also Another one problem, owing to Raman gain coefficienct all ratios of traditional fiber are relatively low, so the optical fiber of general FRA Length even to tens kms at tens kms, makes the FRA of discrete be difficult to reduce volume, limits discrete FRA promotes the use of.

Summary of the invention

It is an object of the invention to provide a kind of Ge-doped double-core photonic crystal fiber, to solve Raman in prior art Amplify and the loss restricted problem of optical fiber telecommunications system.

In order to achieve the above object, the technical solution adopted in the present invention is:

A kind of Ge-doped double-core photonic crystal fiber, it is characterised in that: include quartz body, in described quartz body The heart mixes the conglobate Ge-doped region I of germanium structure, Ge-doped region I form fibre core I, be provided with in quartz body Multiple big airports, multiple big airports are evenly distributed on around Ge-doped region I, and in quartz body, also bias is mixed Enter the conglobate Ge-doped region II of germanium structure, Ge-doped region II form fibre core II, described Ge-doped region I Diameter is more than Ge-doped region II, and Ge-doped region I concentration is different from Ge-doped region II concentration, quartz body In be additionally provided with multiple little airport, multiple little airports are evenly distributed on around Ge-doped region II, described Big airport diameter is more than little airport diameter.

The Ge-doped double-core photonic crystal fiber of described one, it is characterised in that: multiple big airports composition multi-turn Regular hexagon centered by Ge-doped region I, big airport adjacent in each circle big airport of regular hexagon it Between spacing the most equal, multiple little airports composition multi-turn regular hexagon centered by Ge-doped region II, respectively Between little airport adjacent in the circle little airport of regular hexagon, spacing is the most equal, and big airport spacing is more than little Airport spacing.

The invention discloses a kind of Ge-doped double-core photonic crystal fiber, by the parameter to this GD-TC-PCF Design, its effective core area is Tong Bu with the change of wavelength and the tendency of changes of Raman gain coefficienct, thus it draws Graceful gain efficiency coefficient becomes the most smooth.When using this optical fiber as the gain media of raman amplifier, its high and Smooth raman gain efficiency coefficient improves the conversion efficiency of pumping source, only uses single pumping source with regard to energy simultaneously Obtain wider, more smooth Raman amplifier gain spectrum.As can be seen here, utilize that the present invention's is novel GD-TC-PCF manufacture raman amplifier can overcome well current optical fiber telecommunications system loss limit because of Element, this is for improving the quality of FRA and promoting FRA to have important in the application further of fiber optic communication field Meaning.

Accompanying drawing explanation

Fig. 1 is present configuration schematic diagram.

Fig. 2 is Ge-doped region II structural representation in the present invention.

Fig. 3 is that in the specific embodiment of the invention, Raman gain coefficienct and effective core area synchronize with wavelength is close Situation of change schematic diagram.

Fig. 4 is fiber Raman amplifier gain spectral fluctuation situation schematic diagram in the specific embodiment of the invention.

Detailed description of the invention

As shown in Figure 1 and Figure 2.A kind of Ge-doped double-core photonic crystal fiber, includes quartz body 1, quartz Body 1 center mixes the conglobate Ge-doped region I of germanium structure, Ge-doped region I form fibre core I, quartz body 1 In be provided with multiple big airport 2, multiple big airports 2 are evenly distributed on around Ge-doped region I, quartz In body 1, also bias mixes the conglobate Ge-doped region II of germanium structure, Ge-doped region II form fibre core II, germanium Doped region I diameter is more than Ge-doped region II, and Ge-doped region I concentration is with Ge-doped region II concentration not With, quartz body 1 is additionally provided with multiple little airport 3, multiple little airports 3 are evenly distributed on Ge-doped district Around the II of territory, big airport 2 diameter is more than little airport 3 diameter.

Multiple big airports 2 form multi-turn regular hexagon centered by Ge-doped region I, respectively enclose regular hexagon Between big airport 2 adjacent in big airport 2, spacing is the most equal, and multiple little airports 3 form multi-turn with germanium Regular hexagon centered by doped region II, little airport 3 adjacent in each circle little airport of regular hexagon 3 Between spacing the most equal, and big airport 2 spacing is more than little airport 3 spacing.

In the present invention, the diameter mixing germanium region of fibre core I and fibre core II is different, and germania concentration is the most different, bag The diameter of the airport enclosing them is the most different, and larger-diameter fibre core I is at the center of whole optical fiber, less The fibre core II of diameter is distributed prejudicially.Wherein λ and d is spacing and the diameter of little airport respectively, Λ and D divides Not being spacing and the diameter of big airport, R and r represents the Ge-doped radius of two fibre core I and II respectively.

Embodiments of the invention: set single pumping wavelength as 1.495um, flashlight is commonly used in the range of fiber optic communication C-band part, i.e. wave-length coverage is 1.530-1.565um altogether 35nm.Fig. 3 gives the effective fine of the present invention Core area and the synchronous situation of Raman gain coefficienct change.It can be seen from figure 3 that photonic crystal fiber of the present invention has Effect core area is the most consistent with Raman gain coefficienct variation tendency, close to parallel.So, with this photonic crystal light Even if its gain spectral also can be the most smooth in the case of single pumping for the fine raman amplifier manufactured.For testing further Demonstrate,prove this effect, single pumping this photonic crystal fiber to 5km that use wavelength is 1.495um, power is 0.5W Carrying out pumping and constitute Raman Fiber Amplifier, the gain spectral of its C-band is as shown in Figure 4.From fig. 4, it can be seen that whole The gain spectral fluctuation of individual C-band amplifier is the least, only 0.49dB.It addition, because fiber Raman amplifier Amplify wave band only relevant with the wavelength of pumping, for different pumping wavelengths, by choosing different size air Bore dia, airport spacing, Ge-doped radius and concentration, the photonic crystal fiber of the present invention can be used for S-band, The Raman amplifiction of other band signal light such as L-band.

Claims (1)

1. a Ge-doped double-core photonic crystal fiber, it is characterized in that: include quartz body, described quartz body center mixes the conglobate Ge-doped region I of germanium structure, fibre core I is formed by Ge-doped region I, quartz body is provided with multiple big airport, multiple big airports are evenly distributed on around Ge-doped region I, in quartz body, also bias mixes the conglobate Ge-doped region II of germanium structure, fibre core II is formed by Ge-doped region II, described Ge-doped region I diameter is more than Ge-doped region II, and Ge-doped region I concentration is different from Ge-doped region II concentration, quartz body is additionally provided with multiple little airport, multiple little airports are evenly distributed on around Ge-doped region II, described big airport diameter is more than little airport diameter；

Described multiple big airport composition multi-turn regular hexagon centered by Ge-doped region I, between big airport adjacent in each circle big airport of regular hexagon, spacing is the most equal, multiple little airports composition multi-turn regular hexagon centered by Ge-doped region II, between little airport adjacent in each circle little airport of regular hexagon, spacing is the most equal, and big airport spacing is more than little airport spacing.