CN2530275Y - Optical fiber dynamic coupler - Google Patents

Abstract

The utility model relates to an optic fiber dynamic coupling, which comprises a light beam radiating from the input optic fiber group on the front focal plane arranged on the collimation lens group. After passing the collimation lens group and passing a phase plate that is arranged on the front focal plane of the collimation lens group and on the rear focal plane of the converging lens group and is composed of a positive phase plate and a negative phase plate complementing to each other and a movable device, the light beam is converged by the converging lens onto the output optic fiber group on the rear focal plane of the converging lens. The phase plate has the property of the even-number Dammann Grating. Through the half-period displacement, the coupling can realize conversion between the beam splitting and beam combining and thereby has the double functions of dynamic beam splitting and beam combining. The use is convenient, the volume is small and the weight is light. Used as a switch, the utility model is more rapid than the mechanical switch in the prior art, so the coupling has an important use vale in application in development of the optical communication.

Description

Optical fiber Dynamic Coupling device

Technical field:

The utility model relates to a kind of optical fiber Dynamic Coupling device, particularly relates to a kind of dynamic optically-coupled that is suitable for greater number and light beam splitting based on small diffraction optical element.

Background technology:

Along with science and technology development, people have ever-increasing great market demand to message capacity.Optical fiber communication has surmounted traditional cable communication with advantages such as its high speed, high capacity, good confidentiality, low costs, is the direction of 21st century development communication technologies.Light can be with light velocity high-speed transfer information in optical fiber, adopt close wavelength-division multiplex technology can be in an optical fiber transmitting multiplex information, at present by electronics is handled at a high speed, jumbo optical information has become the optical communication technique development bottleneck, therefore, how to realize one the road to multichannel and the multichannel dynamic optical coupling technology to a tunnel, be one of basic function that needs most in the present optical communication, become the key issue that solves the optical communication technique development bottleneck.

Light switching technology in the optical communication is the basic function that needs most in the present Fibre Optical Communication Technology, beam splitting majority in the optical communication at present is that light draws wimble structure, melting structure, can realize the bundle that closes of two optical fiber easily, its advantage is that project organization is simple, be convenient to processing and manufacturing, shortcoming is that fused biconical taper structure number should not be very big, and the closing of optical fiber that is not suitable for big figure fully restrainted and beam splitting.

Diffraction optical element has little, the lightweight advantage of volume, is very suitable for using in optical communication switch.Formerly technology [1] is (referring to J.J.Pan and T.Zhu, " 1 * N fiber coupler employingdiffractive optical element ", Electronics Letters 35, No.4,324-325 (1999)) once proposed to realize 1 * N optical coupling structure, but they do not propose the structure of dynamic optically-coupled, and its structure can only realize the branch beam function with diffraction optical element, can not realize and beam function, can not realize beam splitting and the also conversion between the bundle.

Summary of the invention:

The utility model is based on the immanent structure of even number type Darman raster, it is the π phase reversal characteristic of semiperiod, propose a kind of dynamic photo-coupler with switching mode beam splitter and coupling mechanism function, device promptly of the present utility model both can be realized the branch beam function, can realize the beam function that closes of multiple beam again.

As shown in Figure 1, optical fiber Dynamic Coupling device of the present utility model comprises input optical fibre group 1, collimation lens set 2, the phase board 3, convergent lens 4 and the output optical fibre group 5 that are made of the positive-phase-board 301 and the negative-phase-board 302 of two complementations.Wherein input optical fibre group 1 is placed on the front focal plane of collimation lens set 2, and phase board 3 places on the back focal plane of collimation lens set 2, also is on the front focal plane of convergent lens 4, and output optical fibre group 5 places on the back focal plane of convergent lens 4.Positive-phase-board 301 or negative-phase-board 302 have shifter 6.

The position of the positive-phase-board 301 of two complementations of said formation phase board 3 and negative-phase-board 302 is 0 and π mutually, or 0 and pi/2.

Wherein shifter 6 is to promote moving mutually between the two positive negative-phase-boards 301,302, no when mobile between the positive negative-phase- board 301 and 302, be equivalent to a common two-value position phase Darman raster, after passing through phase board 3 and convergent lens 4 from the light beam of input optical fibre group 1 again through collimation lens set 2 collimations, will evenly equally be diffracted in the output optical fibre group 5.After shifter 6 promotes the mobile half period of negative-phase-board 302 (or 301), positive negative-phase- board 301 and 302 position sum mutually are zero, therefore, from the light of input optical fibre group 1 will be fully by convergent lens 4 pinchings in an optical fiber of the output optical fibre group 5 that is placed on convergent lens 4 focus places, realized closing the function of bundle.

Introduce the characteristic of Darman raster below simply, and how to utilize the characteristic of Darman raster to realize function of the present utility model.The design details of relevant Darman raster can be consulted technology [2] (ChangheZhou, and Liren Liu, " Numerical study of Dammann array illuminators ", Appl.Opt.34,5961-5969 (1995)) formerly.

The consideration process of Darman raster is: the transmitance for a rectangular element is distributed as $t_k\left(x\right)=\mathrm{rect}\left(\frac{x-(x_{k+1}+x_k)/2}{x_{k+1}-x_k}\right)-----\left(1\right)$ Wherein x is the distance of position phase inversion point, x _kBe the distance of k position phase inversion point, x _K+1It is the distance of k+1 position phase inversion point.Its Fourier transformation then is so α wherein _k=2n π x _k, n is that the order of diffraction of Darman raster is inferior, α _kThe corresponding phasing degree that is k position phase inversion o'clock on n order diffraction level time.

Total spectrum point intensity can be expressed as: $I_n=\left(\frac{1}{2\mathrm{n\&pi;}}\right)[{{\left(P_n\right)}_{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">R</figure-callout>}}}^2+{{\left(P_n\right)}_l}^2]-------\left(3\right)$ I wherein _nBe the light intensity on the Darman raster n order diffraction level time, ${\left(P_n\right)}_R=\underset{k=0}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k(\sin {\mathrm{\&alpha;}}_{k+1}-{\sin \mathrm{\&alpha;}}_k)$ $=2\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^{k+1}{\sin \mathrm{\&alpha;}}_k-\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">sin</figure-callout>}2\mathrm{n\&pi;}$ ${\left(P_n\right)}_I=\underset{k=0}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k({\cos \mathrm{\&alpha;}}_{k+1}-{\cos \mathrm{\&alpha;}}_k)$ $=2\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^{k+1}{\cos \mathrm{\&alpha;}}_k-\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">cos</figure-callout>}2\mathrm{n\&pi;}-1$ (4) (P wherein _n) _RBe the summation of all phase inversion o'clock real part intensity on n order diffraction level time, (P _N) _ISummation for all phase inversion o'clock imaginary part intensity on n order diffraction level time.Formula (3) can be simplified, and for zero level spectrum point intensity is: ${\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="Y0125500700112.png,Y0125500700122.png"\; state="\{\{state\}\}">I</figure-callout>}}_0={[1+2\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k{x}_k]}^2-------\left(5\right)$ I wherein ₀Be the light intensity on the zero level spectrum point.To non-zero order spectrum point intensity be $I_n={\left(\frac{1}{\mathrm{n\&pi;}}\right)}^2\{{\left[\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k{\sin \mathrm{\&alpha;}}_k\right]}^2+{[1+\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k{\cos \mathrm{\&alpha;}}_k]}^2\}-------\left(6\right)$ For the odd number array illuminator, diffraction efficiency is defined as: $\mathrm{\&eta;}={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="Y0125500700112.png,Y0125500700122.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+2\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{I}_i-----\left(7\right)$ For the even arrays luminaire, diffraction efficiency is defined as: $\mathrm{\&eta;}=2\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{I}_{2i-1}------\left(8\right)$ Even number type Darman raster has such characteristics, and promptly the position of preceding semiperiod distributes mutually and accurately equals a π phase reversal that distributes mutually in later half cycle:

(x _k+ d/2)= (x _k)+π (9) as shown in Figure 2.Utilize this characteristic, the utility model provides two kinds to realize Dynamic Coupling and the formation of also restrainting.

For the position of two positive negative-phase-boards of first kind of formation is 0 and π mutually, and wherein the position of positive-phase-board 301 is distributed as mutually:

Shown in Fig. 3 (a), k=1 wherein, 2 ... K.x _k=0.5 correspondence be half period, the x=1.0 correspondence be one-period.The position of another negative-phase-board 302 is distributed as mutually:

Shown in Fig. 3 (b), k=1 wherein, 2 ... K.By the displacement of semiperiod between these two the positive negative-phase-boards 301,302, realize partial wave and the switch transition of closing ripple.Two positive negative-phase-boards 301,302 are equivalent to two phase gratings 301,302, when their displacement is zero,

Total position phase sum just in time is the distribution of even number type Darman raster, has therefore realized the function of beam splitter.

After between two positive negative-phase-boards 301,302 displacement of semiperiod being arranged, its total position is distributed as mutually: Total phasic difference is zero.All are behind the such phase board of light beam process of collimation lens set 2 collimations, because total phasic difference of phase board is zero, to have only on the convergent lens zero level spectrum point (being focus) light distribution will be arranged, promptly all light beams from input optical fibre are converged on the output optical fibre that is placed on the convergent lens zero level spectrum point, have realized the function of wave multiplexer.

For second kind of position that constitutes two positive negative-phase-boards 301,302 is 0 and during pi/2, as shown in Figure 4 mutually.Be equivalent to traditional Darman raster is divided into two (0, pi/2) position identical grating 301,302 that distributes mutually equably, as shown in Figure 4, these two positive negative-phase-boards distribute and are: wherein _DAM(x _k) be the position distribution mutually of common Darman raster.When these two phase grating 301,302 displacements were zero, total position distributed mutually and is traditional Darman raster, from the light of input optical fibre behind collimation lens set 2 collimations, will be divided into multi-beam equably by it,, realize the function of beam splitting so that be coupled in the output optical fibre group 5.After the accurately mutual displacement half period of these two phase gratings 301,302, because the reverse speed characterisstic of even number type Darman raster semiperiod, at this moment the position phase sum of two phase gratings is zero,

=0 therefore, passes through with regard to zero deflection ground from the light of input optical fibre group 1, and collected on the output optical fibre that is placed on the focus place by convergent lens.

More than two kinds of structures are the distribution characters that utilized even number type Darman raster, it is the π phase reversal characteristic of semiperiod, the phase grating 301 that traditional Darman raster is divided into two complementations, 302, when these two phase gratings 301, when the displacement between 302 is zero, can both realize the function of traditional Darman raster, i.e. the function of beam splitting; When these two phase gratings 301, after the 302 accurately displacement half period, because these two phase gratings 301,302 complementarity, total phasic difference is zero, and therefore, light beam can not have deviation ground to be passed through, all converged in the output optical fibre on the focus that is placed on convergent lens 4 from all light beams of input optical fibre group 1, promptly realized closing beam function.These two kinds of formations relatively see Table 1.Meaning of the present utility model just is to have realized dynamic optical coupling technology, can realize the branch beam function, also can realize closing beam function, and this is that formerly technology is not available.

Be used for close wavelength-division multiplex technology, can transmit the channel of a plurality of wavelength in optical fiber, the difference of wavelength can cause following two kinds of errors.First kind of error is the phase error that positive negative-phase- board 301 and 302 corresponding different wave lengths cause.Physics depth of modulation on the phase board is constant, so the different corresponding position of wavelength is different mutually.Can accurately manufacture phase board is that modulate mutually accurate π position for certain centre wavelength (for example centre wavelength channel 1550nm).When the wavelength of transmission signals in the optical fiber was 1570nm, this is just corresponding departed from the error of π position phase, then this moment each spectrum point intensity can calculate by following formula: ${\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="Y0125500700112.png,Y0125500700122.png"\; state="\{\{state\}\}">I</figure-callout>}}_0={[1+2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\frac{\mathrm{\&theta;}}{2}\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k{x}_k]}^2-------\left(16\right)$ $I_n={\left(\frac{\sin \frac{\mathrm{\&theta;}}{2}}{\mathrm{n\&pi;}}\right)}^2\{{\left[\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k{\sin \mathrm{\&alpha;}}_k\right]}^2+{[1+\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{(-1)}^k\cos {\mathrm{\&alpha;}}_k]}^2\}------\left(17\right)$ In the formula (16), θ is the angle that departs from π position phase.For even number type Darman raster array illuminator, then have: ${\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="Y0125500700112.png,Y0125500700122.png"\; state="\{\{state\}\}">I</figure-callout>}}_0={\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\frac{\mathrm{\&theta;}}{2}------\left(18\right)$ $I_n={\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="Y0125500700111.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\frac{\mathrm{\&theta;}}{2}p\left(n\right)------\left(19\right)$ The different corresponding linear phase change amounts of wavelength are: $\mathrm{\&theta;}=\frac{1570-1550}{1550}\mathrm{\&pi;}=\frac{2}{155}\mathrm{\&pi;}------\left(20\right)$ With this value substitution following formula (18,19), can get: I ₀=0.0004, I _n=0.999p (n), promptly central spectral point intensity has only increased less than per mille, spectrum point intensity at different levels reduced per mille equably.This influence other error effect relatively is very little.This shows that the difference of wavelength is very little to the influence of homogeneity and diffraction efficiency.

The difference that second kind of error is wavelength will cause the difference by phase board diffraction light angle of diffraction.For example: for the cycle d=500 μ m of phase board 3, focal distance f=50mm, input optical fibre group 1 output light wavelength λ=1550nm, the spacing of even level spectrum point is 155 μ m, when lambda1-wavelength is changed to 1570nm, spacing between even level spectrum point is 157 μ m, and this is equivalent to the diffracted beam for λ=1570nm, and 2 μ m have only been moved at the diffraction center on output plane.Consider that the optical fiber core diameter has 90 μ m, the amount of movement of center spot 2 μ m is very little, so the dynamic photo-coupler of the utility model can adopt for dense wave division multipurpose.

On the main structure of the utility model with not being both of technology formerly: formerly be a phase board in the technology, and the utility model is the positive negative-phase-board that adopts two complementary distributions, and the plus or minus phase board has shifter, realize moving between these two phase boards, to realize dynamic beam splitting and the function of closing bundle.

Because the characteristics of the even number type Darman raster that the utility model adopts, semiperiod, less displacement just can realize the conversion of beam splitter and bundling device, less displacement just can realize the beam splitting and the switching function that closes bundle of light beam, so volume is little, in light weight, the saving energy, simple compared with the control of the mechanical optical switch in the technology formerly, speed is fast, because the manufacturing process of phase board is the technology compatible mutually with the large scale integrated circuit technology, therefore, can duplicate production in enormous quantities, cost can reduce, and obvious superiority is arranged.Particularly (for example: 8 * 16,16 * 32 etc.), when present mechanical light switching technology realized than difficulty, the utility model just had obvious superiority, and the use value of particular importance is arranged to large-scale optical switching array in the future development.

Compare with technology [1] formerly, the utility model has following characteristics: dynamic photo-coupler of the present utility model provides beam splitting and has closed the dual-use function of bundle, and formerly technology can only provide the function of beam splitting, and the function of closing bundle can not be provided.Core of the present utility model has been to utilize fully the semiperiod π phase reversal characteristic of even number type Darman raster, and even number type Darman raster is divided into the grating of two phase reversals, by the displacement of semiperiod, has realized beam splitting and the conversion of closing bundle.Because light switching technology (comprise beam splitting and close bundle) is one of key core technology of following optical communication development, therefore, the switching mode beam splitting that the utility model proposes will have important use to be worth with the structure of closing bundle.

It is to be noted, be not to realize that the Darman raster of arbitrary number all can be divided into the phase grating of two complementations, according to the two-value position Darman raster structure that distributes mutually, have only the Darman raster of even number type to have the characteristic of semiperiod π phase reversal, could be divided into the phase grating of two complementations according to structure of the present utility model.The Darman raster of odd number type is not owing to possess the π phase reversal characteristic of semiperiod, the phase grating that therefore can not be divided into two complementations by structure of the present utility model, this that is to say, structure of the present utility model can only realize the optical fiber output array of even number type, this problem is theoretic restriction, rather than the restriction in the practicality.The simplest solution of odd number type output array is increased by one tunnel output exactly, make it become the even number output array, and with the poorest a road need not the getting final product of signal to noise ratio (S/N ratio) in the output optical fibre array.

The utility model can be arranged in the form of two dimension fully, and the right-angled intersection of one dimension Darman raster just can be arranged in two-dimentional Darman raster.Adopt two-dimensional encoded form just can realize the coupling of the photokinesis in the input optical fibre is outputed in the two-dimentional output optical fibre array, realize the function of two-dimentional beam splitting; After the X-axis displacement of (or Y-axis) semiperiod, being equivalent to total phasic difference is zero, and therefore, the light beam in the input optical fibre group just is coupled in the optical fiber that is placed on convergent lens central authorities zero level fully, has realized the function that two dimension is closed bundle.

Description of drawings:

Fig. 1 is the structural representation of the utility model Dynamic Coupling device.

Fig. 2 is the position phase distribution plan of even number type Darman raster.In order to illustrate the convenience of semiperiod π phase reversal, the position be worth to distribute mutually be designated as (pi/2 ,-pi/2), this be equivalent to fully the neighborhood phasic difference for (0, π).

Fig. 3 is the formation of first kind of phase board of the utility model, and Fig. 3 (a), Fig. 3 (b) are respectively the synoptic diagram that the position distributes mutually in positive 301, the 302 single cycles of negative-phase-board.

Fig. 4 is the formation of second kind of phase board of the utility model.

Embodiment:

Structure as shown in Figure 1.

, behind collimation lens set 2 collimation, impinge upon on the phase board 3 by the light beam of the 1550nm of emission in 1 * 4 the input optical fibre group 1, behind phase board 3 diffraction, on the back focal plane of convergent lens 4, be coupled in the output optical fibre group 5.The core diameter of optical fiber is 250nm, the parameter of phase board 3: the cycle is d=500 μ m, and area of raster is 20mm * 20mm, is 1 * 16 Darman raster, is made by the binary optical technology, and the concrete parameter of the position phase inversion point in one of them cycle sees Table 2.Template is made by electron beam or other plate-making technology.On substrate of glass, coat photoresist, after even glue, exposure, development, just can be to photoresist with the design transfer on the template.Utilize wet-chemical etching technology and high-density plasma etching technics, just can on substrate of glass, etch the Darman raster 301 and 302 of the required pi/2 position phase degree of depth.Shifter 6 is no when mobile, and all are diffracted in 1 * 16 output optical fibre group 5 equably from the light in the input optical fibre group 1, and every road output optical fibre all can receive the signal of 1 * 4 input optical fibre group any a tunnel simultaneously.Here it is has realized the function of beam splitting.After shifter 6 promotion negative-phase-boards 302 move semiperiods 250 μ m, all all are collected on the output optical fibre of central zero level from the light in the input optical fibre group 1, other output optical fibre of next door is collected less than the light from input optical fibre group 1, and therefore Here it is has finished the function of closing bundle.

Table 1 is realized the comparison of two kinds of formations of the present utility model.

	The position distributes mutually	The template number
			Constitute 1	0，π	2
Constitute 2	0，π/2	1

The concrete numerical value of the position phase inversion point in the one-period of table 21 * 16 Darman raster (500 μ m).

X 0	X 1	X 2	X 3	X 4	X 5	X 6	X 7	X 8	X 9
										0	70.415	87.845	110.735	133.5	178.255	197.68	219.67	226.175	250.0

X 10	X 11	X 12	X 13	X 14	X 15	X 16	X 17	X 18
									320.415	337.845	360.735	383.5	428.255	447.68	469.67	476.175	500.00

Claims (2)

1. optical fiber Dynamic Coupling device, comprise collimation lens set (2), place the input optical fibre group (1) on collimation lens set (2) front focal plane, convergent lens (4) is arranged and place output optical fibre group (5) on convergent lens (4) back focal plane, it is characterized in that on the back focal plane of collimation lens set (2), be equipped with on the front focal plane of convergent lens (4) by the positive-phase-board (301) of two complementations and the phase board (3) of negative-phase-board (302) formation, positive-phase-board (301) or negative-phase-board (302) have shifter (6).

2. optical fiber Dynamic Coupling device according to claim 1, the position that it is characterized in that the positive-phase-board (301) of two complementations of said formation phase board (3) and negative-phase-board (302) they are 0 and π mutually, or 0 and pi/2.

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