CN101562494B - Optical time division multiplexer and manufacturing method - Google Patents
Optical time division multiplexer and manufacturing method Download PDFInfo
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- CN101562494B CN101562494B CN 200910083344 CN200910083344A CN101562494B CN 101562494 B CN101562494 B CN 101562494B CN 200910083344 CN200910083344 CN 200910083344 CN 200910083344 A CN200910083344 A CN 200910083344A CN 101562494 B CN101562494 B CN 101562494B
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Abstract
The invention relates to an optical time division multiplexer, which consists of a multi-level Wightman interferometer. Each level of Wightman interferometer consists of a fiber pigtail, a self-focusing lens and a light splitting film; the fiber pigtail is coupled with the self-focusing lens to form a fiber collimating lens; the end face of the fiber collimating lens is plated with the light splitting film; a pair of the fiber collimating lenses plated with the light splitting film form a fiber light-splitting device; two fiber light-splitting devices form a level of the Wightman interferometer; and each level of the Wightman interferometer can double the optical signal rate by properly adjusting the length difference of interference arms, and n levels of the Wightman interferometer can improve the optical signal rate by n times, wherein n is 1, 2, 3, 4, and the like. The optical time division multiplexer has the advantages that: based on the defect improvement of the conventional timedivision multiplexer, compared with the time division multiplexers of foreign companies, the optical time division multiplexer is superior to the foreign products in the aspects of loss, wavelength flatness, polarization sensitivity, temperature stability and the like, and has low manufacturing cost and large commercial value.
Description
Technical field
The present invention relates to a kind of optical time division multiplexer and manufacture method, belong to areas of information technology.
Background technology
Increasing substantially of message capacity is the inexorable trend of informationized society development, and Optical Time Division Multiplexing Technology (OTDM) and close wavelength-division multiplex technology (DWDM) are two important effective ways that improve the optical fiber communication capacity.OTDM technology and DWDM technology are to realize two kinds of different technologies routes of following high speed, high-capacity optical fiber communication system, utilize separately any technology can construct jumbo optical fiber telecommunications system.OTDM technology and DWDM technology combine, and just can take full advantage of the advantage of these two kinds of technology and dig the shortcoming of abandoning them, jointly construct at a high speed, future of high-capacity optical fiber communication system.
Some developed countries actively push forward the dwdm optical communication system practical in, also actively promoting the development of 0TDM optical communication system.On June 19th, 2007--Britain Virtual network operator JANET announces to have realized that the while is for the single channel 40Gbps transmission of transport layer and IP layer, JANET represents than the mode that increases the 10Gbps channel, adopt the 40Gbps transmission rate to have more cost advantage, also easier, JANET represents, they and Ciena cooperate with Verizon Business in transportation level, then cooperate with Juniper with Alcatel Lucent in the IP aspect.To ultrahigh speed OTDM technology, Japan has shown positive attitude.Japan Post(Japan Postal Service) is economized and is entrusted NTT company to utilize the optical fibre ring mode-locked laser to realize the OTDM transmission experiment of 640Gbit/s, in 2007, the Alcatel-Lucent of the U.S. and Canadian Nortel have showed respectively 6.4Tbit/s (the DWDM/OTDM mixed light communication system of 2 * 40Gb/s * 80ch), and claim the commercial DWDM/OTDM communication system that is about to release the current highest level of representative.There had been the network demand of 40Gbit/s in China in recent years, the following demand that will have 160Gbit/s, the effective way of development vast capacity transmission network in view of the OTDM technology, the OTDM communication system is take the high-speed optical signal treatment technology as the basis, fully compatible, rising greatly with the all-optical network in future.
Optical time division multiplexer is the core devices of OTDM technology, the signal quality after only having the optical time division multiplexer guarantee of function admirable multiplexing.The optical time division multiplexer of report is mark-Zehnder interferometer (M-Z) type structure (Mike J at present, the people such as O ' Mahony, IEEE Communications Magazine, December1995,82-88), (Wei road equality people, optical communication research, the 2nd phase in 1999,43-47).This M-Z interferometer is made of light-splitting device and time delay device, light-splitting device is divided into again: (1) planar waveguide-type (Jepsen, K.S. wait the people, Conferenceon Optical Fiber Communication, Technical Digest Series, 1998, p 310-311), the controllability of its time delay device is good, but insertion loss is large and expensive; (2) the fused-tapered fiber coupler type (favour war is strong to wait the people, science and technology and engineering, the 8th in September, 2008 volume the 17th phase, 4999-5001), above-mentioned adaptive multiplexer separation/combination is only finished by the optical coupling that drawing-down optical fiber produces.When light source time/when the spatiality condition satisfies, cause strong interference effect, the amplitude of each road light pulse is not to be in stable state, but constantly irregularly rises and falls, especially when rocking the optical time division multiplexer input end fiber, pulse ripple is more remarkable.The splitting ratio of fused tapered optical fiber coupler is the poor Sensitive Apparatus of polarization phase, and under the constant condition of input power, power of certain output branch road can change along with the change of input polarization.The characterisitic parameter of each fused tapered optical fiber coupler has a little difference, and consistency is poor.Polarization dependent loss is bigger than normal, and has larger First-Order Polarization Mode Dispersion (PMD).The wavelength dependency of splitting ratio is large.The long-time use, temperature and the impact of strain unsteadiness of multistage fused tapered optical fiber coupler stack accumulation become large, so that after the above-mentioned multiplexer of making placed a period of time, performance change was remarkable, splitting ratio and the Ge Lu signal amplitude value situation when just having completed differs greatly, and is difficult to practical.
The coherence is relevant with the light source size, and is theoretical according to Huygens-Fresnel, the optical disturbance on the interference surface be put thus and light source between each secondary wave of sending on certain face be formed by stacking.Through analysing in depth and repetition test, find that fused tapered optical fiber coupler draws cone in fact to dwindle " light source " size, consider from spatial coherence, be equivalent to increase the coherence; And, the sin of fiber coupler
2(Cz) dichroism has been aggravated interference sensitiveness, sin
2(Cz) relation makes the wavelength flatness also relatively poor.
If optical time division multiplexer all adopts the traditional optical device, complex structure and with coupling fiber and adjust difficulty (referring to: the German u2t company optical time division multiplexer description of product).
Summary of the invention
In order to overcome the deficiency of prior art structure, problem for the existence of said structure optical time division multiplexer, the employing of the present invention innovation the novel Paul Whiteman type interferometer structure optical time division multiplexer that combines with plated film bulk optics device of optical fiber, solved the stability problem of optical time division multiplexer, the optical time division multiplexer of this structure has no report both at home and abroad.The invention provides a kind of optical time division multiplexer and manufacture method.
The technical solution adopted for the present invention to solve the technical problems is:
A kind of optical time division multiplexer, consisted of by multistage Paul Whiteman interferometer, the spectro-film of placing 1: 1 splitting ratio between a pair of fiber collimating lenses consists of optical fiber lens type light-splitting device, spectro-film is a minute amplitude type, divide the light time not change phase place, two above-mentioned optical fiber lens type light-splitting devices consist of the one-level of Paul Whiteman interferometers; Every grade of Paul Whiteman interferometer is by optical fiber pigtail, GRIN Lens, and spectro-film consists of; Optical fiber pigtail and GRIN Lens coupling consist of fiber collimating lenses; Plate spectro-film at the fiber collimating lenses end face;
Input signal enters the light-splitting device that is made of the GRIN Lens plating spectro-film with tail optical fiber and is divided into two, one tunnel reflection, one Reuter penetrates, reflection and transmission signal move ahead along two arms that optical fiber consists of, optical fiber two arm lengths are adjusted to and are satisfied the signal frequency multiplication requirement, when arriving the light-splitting device of another Opposite direction connection, synthesize one road signal;
The the 1 road and the 2 tunnel optical fiber length difference DL
iSatisfy:
Wherein c is light transmission speed in a vacuum; N is the refractive index in fiber cores district; Footmark i is the rank of Paul Whiteman interferometer, i=1,2,3,4......;
M=2
i, T
0Be the pulse repetition period before the time division multiplexing; Every one-level Paul Whiteman interferometer according to
Adjust the 1 road and the 2 tunnel optical fiber length difference DL
i, light signal speed is doubled;
The connected mode of every one-level Paul Whiteman interferometer and next stage Paul Whiteman interferometer is for connecting; The fiber lengths no requirement (NR), multistage Paul Whiteman interferometer is connected, and n level Paul Whiteman interferometer is brought up to 2 of original speed with light signal speed
nDoubly, n=1,2,3,4......;
1, plate spectro-film with the GRIN Lens of tail optical fiber,
Optical fiber pigtail, GRIN Lens, spectro-film;
The length of GRIN Lens was 1/4th cycles, non-parallel light can be become directional light when arriving the spectro-film plane, and GRIN Lens and optical fiber pigtail are integrated, such as Fig. 6;
Light-splitting device adopts the extraordinary spectro-film of consistency, guarantees the splitting ratio 1: 1 of each component optical device, and small difference is corrected by the reciprocity connected mode of reflection end and transmission end;
Spectro-film is the interference spectro-film that generally adopts;
2, Paul Whiteman interfere type optical time division multiplexer;
The formation of Paul Whiteman interfere type optical time division multiplexer one-level as shown in Figure 7, input signal enters the light-splitting device that is made of the GRIN Lens plating spectro-film with tail optical fiber and is divided into two, one tunnel reflection, one Reuter penetrates, reflection and transmission signal move ahead along Paul Whiteman interferometer two arms that optical fiber consists of, optical fiber two arm lengths are adjusted to and are satisfied the signal frequency multiplication requirement, when arriving the light-splitting device of another Opposite direction connection, synthesize one road signal;
3, mark's zehnder type (M-Z type) optical time division multiplexer;
The formation of mark's zehnder type optical time division multiplexer one-level as shown in Figure 8, input signal enters the light-splitting device that is made of optical fiber fused tapering and is divided into two, one tunnel reflection, one Reuter penetrates, reflection and transmission signal move ahead along mark's Zehnder interferometer two arms that optical fiber consists of, optical fiber two arm lengths are adjusted to and are satisfied the signal frequency multiplication requirement, when arriving the light-splitting device of another Opposite direction connection, synthesize one road signal;
4, full polarization M-Z interferometer structure optical time division multiplexer;
The formation of full polarization M-Z type optical time division multiplexer one-level as shown in Figure 9, input signal enters the inclined to one side light-splitting device of the guarantor who is made of the polarization maintaining optical fibre fused biconical taper and is divided into two, one tunnel reflection, one Reuter penetrates, reflection and transmission signal move ahead along full polarization M-Z interferometer two arms that optical fiber consists of, optical fiber two arm lengths are adjusted to and are satisfied the signal frequency multiplication requirement, when arriving the inclined to one side light-splitting device of guarantor of another Opposite direction connection, synthesize one road signal;
Contrasting above three kinds of optical time division multiplexers can find out, Paul Whiteman interfere type optical time division multiplexer does not need optical fiber fused tapering, arriving when dividing optical position is directional light, and the GRIN Lens clear aperture is that its optical path analysis can adopt the ray tracing mode more than the millimeter magnitude; And M-Z type and full polarization M-Z type optical time division multiplexer are realized light splitting to the optical fiber fused tapering light splitting by the electromagnetic field couples effect of drawing the position, tapering to cause, and its optical path analysis must adopt the Maxwell equation analysis of electromagnetic field.
A kind of optical time division multiplexer manufacture method contains the step that the fiber cut welding is adopted in the time delay adjustment; Step is as follows:
The time delay adjustment is taked to control fibre optic interferometer and is interfered arm lengths to realize; With optical fiber according to the time delay length requirement with after the cutting of the optical fiber cutter of scale, use the optical fiber splicer welding;
The coupling arm light pulse is inserted in the centre of straight-through arm light pulse;
The step that time delay is adjusted is as follows:
Relation between the changes delta L of fiber lengths and the pulse shift position Δ t is shown below,
Wherein Δ L represents the variation of fiber lengths, and Δ t represents the variation of pulse shift position, and c represents the light velocity in the vacuum, is 3 * 10
8M/s, n represent the refractive index of fiber core layer;
Calculate the pulse reflection end fiber lengths that every mobile 1ps need to adjust on oscilloscope;
The accurate adjustment time delay;
By the method for collimating lens plating spectro-film, small difference can be regulated by little flexure stress of optical fiber self, and the amplitude of every one-level is adjusted successively, with amplitudes at different levels the assurance after unanimously;
The time division multiplexing speed that reaches when needs is higher, and the oscilloscope bandwidth is when inadequate, adopt the decay that increases respectively a certain road in the two-way, make it to be converted into the delay inequality of the light pulse of on oscilloscope, observing respectively two-way low rate grade, then reach the purpose of equivalent observation two-forty grade light pulse;
After the time delay adjustment is finished, adopt the optical fiber splicer welding that fused fiber splice is connect, and add heat-seal with heat-shrink tube.
Experimental result shows that time delay precision of the present invention reaches 0.007ps, namely is better than 1.5 μ m, satisfy the above single channel traffic rate of 160Gb/s transmission requirement fully, and the stability of time delay has also obtained checking in experiment.
Beneficial effect of the present invention is on the improved basis of traditional adaptive multiplexer shortcoming, the adaptive multiplexer of contrast offshore company, the present invention all is better than external product at aspects such as loss, wavelength flatness, polarization sensitivity, temperature stabilities, and cost of manufacture is low, has very large commercial value.
Description of drawings
Fig. 1 fiber collimating lenses structural representation of the present invention;
Plating semi-transflective reflective membrane structure schematic diagram on Fig. 2 fiber collimating lenses of the present invention;
Fig. 3 optical fibre light splitting device of the present invention structural representation;
Fig. 4 one-level Paul Whiteman of the present invention interferometer structure schematic diagram;
Fig. 5 n level of the present invention Paul Whiteman interferometer structure schematic diagram;
The effect schematic diagram of Fig. 6 optical splitter in light path;
Fig. 7 one-level Paul Whiteman interfere type optical time division multiplexer;
Fig. 8 M-Z interferometer type optical time division multiplexer;
The full polarization M-Z of Fig. 9 interferometer type optical time division multiplexer;
The GRIN Lens plating spectro-film model schematic diagram of Figure 10 band tail optical fiber; Wherein: a, b and c are optical fiber pigtail, and Lends is GRIN Lens, and Q is spectro-film.
The fused tapered optical fiber coupler schematic diagram that Figure 11 is traditional;
The multiplexing schematic diagram of Figure 12 Paul Whiteman interfere type optical time division multiplexer one-level;
Figure 13 mark zehnder type (M-Z type) optical time division multiplexer Interference Model schematic diagram;
The full polarization M-Z of Figure 14 interferometer structure optical time division multiplexer;
Figure 15 fiber end face is fired into lens Paul Whiteman interferometer type optical time division multiplexer;
Figure 161 60GHz optical time division multiplexer structure chart;
Figure 17 Paul Whiteman interfere type optical time division multiplexer 1 * 4 multiplexing schematic diagram;
Figure 18 oscilloscope observation 160GHz optical time division multiplexer time delay precision;
Figure 19 oscilloscope observation 160GHz optical time division multiplexer time delay precision;
Waveform schematic diagram on Figure 20 oscilloscope;
Waveform schematic diagram on Figure 21 oscilloscope.
The present invention is further described below in conjunction with drawings and Examples.
Embodiment
Embodiment 1: as shown in Figure 4,1 grade of Paul Whiteman interfere type optical time division multiplexer, when multiplexing front frequency was 2.5GHz, multiplexing rear frequency was 5GHz, GRIN Lens adopts the excellent lens with collimated light function of 1/4th pitches.The refraction index profile of GRIN Lens is:
n＝n
0[1-1/2Ar
2] (1)
In the formula, n
0Be the refractive index of axle upper glass, A is distributed constant, and r is radius.
Approximate lower at paraxial meridian, equations of light ray is reduced to
Wherein, x represents light to the vertical range in axle center, and z represents the horizontal level take the incident end as starting point.
To (2) formula integration, and bring boundary condition into and get:
X in the formula
0, θ
0Respectively incident ray height and incidence angle, x
c, θ
cBe emergent ray height and the angle of emergence, L is the distance that optical fiber is walked in the z direction;
Distinguishingly, when the two lens distributed constants that adopt are identical, and length is P/4, i.e. L
1=L
2=p/4 and A
1=A
2During=A (wherein P is pitch), have
So light position and the angle that can from second lens, be penetrated by formula (4):
Namely
If this moment, the Axis centre index of two GRIN Lens was identical, then have
This shows, in second lens in the light of outgoing and the first lens light of incident be symmetric relation with respect to optical axis.Placed side by side and lens two ends all are connected to optical fiber pigtail with two lens.Owing to be coated with spectro-film, so these lens are a half-transmitting and half-reflecting spectroscope in fact; By adjusting the coating process parameter, can accomplish 1: 1 splitting ratio, by the invertibity of light path, two long is that the lens combination of 1/4th pitches can be combined into two ways of optical signals one road signal.Linking two component light microscopics is Paul Whiteman interferometer form, consists of collimation light splitting type 20GHz optical time division multiplexer;
The making difficult point of optical time division multiplexer is that accurate delay of control is poor, makes the light pulse of every road be inserted in prime pulse middle, and the 5GHz repetition rate requires pulsion phase every 200ps.Specific practice is as follows: choose one road signal as a reference, another road produces with it the delay inequality of Δ Ti;
M=2 wherein, 4,8,16; I=1,2,3,4.Corresponding optical fiber length difference calculates according to following formula:
Wherein C is light transmission speed in a vacuum, and n is the refractive index in fiber cores district;
The time delay adjustment is taked to control fibre optic interferometer and is interfered arm lengths to realize.With optical fiber according to the time delay length requirement with after the cutting of the optical fiber cutter of scale, use the optical fiber splicer welding.Suppose that the original pulse repetition rate is f
0=2.5GHz, in order to form the repetition rate of 5GHz, the coupling arm light pulse must be inserted in the centre of straight-through arm light pulse.When time delay was adjusted, the relation between the changes delta L of fiber lengths and the pulse shift position Δ t was shown in (8) formula, and wherein Δ L represents the variation of fiber lengths, and Δ t represents the variation of pulse shift position, and c represents the light velocity in the vacuum, is 3 * 10
8M/s, n represent the refractive index of fiber core layer.What use is common G652 monomode fiber, and the sandwich layer refractive index is about 1.443; Calculate like this pulse every mobile 1ps on oscilloscope and need to adjust the about 0.21mm of reflection end fiber lengths.Adopt cleverly fiber cut and fusion techniques, the accurate adjustment time delay.By the method for collimating lens plating spectro-film, guaranteed the consistency of splitting ratio, small difference can be regulated by little flexure stress of optical fiber self, shown in Figure 20,21.
Waveform on Figure 20 oscilloscope is multiplexing front 2.5GHz pulse, and adjacent pulse is spaced apart 400ps, and the waveform of Figure 21 is the multiplexing rear 5GHz impulse waveform of one-level Paul Whiteman interferometer, shows among the figure that the pulse spacing becomes 200ps.
After the time delay adjustment is finished, adopt the optical fiber splicer welding that fused fiber splice is connect, and add heat-seal with heat-shrink tube.
The present invention has following technical characterictic:
1, plate spectro-film as shown in figure 10 (necessary technical characterictic) with the GRIN Lens of tail optical fiber,
Wherein: a, b and c are optical fiber pigtail, and Lends is GRIN Lens, and Q is spectro-film.
GRIN Lens becomes directional light with non-parallel light when arriving the spectro-film plane, satisfy spectro-film to the requirement of light angle, has avoided pyrometric cone coupler (or waveguide coupler) to need the interference of drawing-down optical fiber (or levigate waveguide) light splitting unstable.
After GRIN Lens and optical fiber pigtail are integrated, have overcome the conventional bulk optical interdferometer and be difficult to and the coupling fiber problem.
Light-splitting device adopts the extraordinary spectro-film of consistency, guarantees the splitting ratio 1: 1 of each component optical device, and small difference is corrected by the reciprocity connected mode of reflection end and transmission end.
Spectro-film is designed to polarization independent type, different from the partial wave previous mode of fused tapered optical fiber coupler (or waveguide coupler), spectro-film is a minute amplitude type, and the former changes phase of light wave in minute light time, the latter does not change phase place, and the good stability of this adaptive multiplexer is in the former.Spectro-film technique can realize the light splitting that the broadband is smooth, and wavelength dependency is very little in transmission bandwidth.The spectro-film device technology is ripe, and temperature stability is good.Traditional fused tapered optical fiber coupler schematic diagram as shown in figure 11.
2, Paul Whiteman interfere type optical time division multiplexer as shown in figure 12 (necessary technical characterictic);
Paul Whiteman interfere type optical time division multiplexer is made of multistage.Every one-level can improve n doubly with light signal speed, n=1,2,3,4.......
The interference disturbance of Paul Whiteman type optical time division multiplexer is certainly relevant from wave field mainly, belongs to a minute amplitude type interference device, and is different with waveguide type M-Z interferometer type optical time division multiplexer from the fused tapered optical fiber coupler type.
3, mark's zehnder type (M-Z type) optical time division multiplexer Interference Model schematic diagram as shown in figure 13;
Full polarization M-Z interferometer structure optical time division multiplexer as shown in figure 14;
4, the method (non-essential technical characterictic) of fiber cut fusion is adopted in the time delay adjustment
Experimental result shows that time delay precision of the present invention reaches 0.007ps, namely be better than 1.5 μ m, and the stability of time delay has also obtained checking in experiment.
Embodiment 2: following several structures all belong to this patent claimed range:
(1) fiber end face is fired into lens shape with various mode of heatings, and light is become directional light; Between a pair of this device, place spectro-film or the light splitting piece of various splitting ratios, the optical fiber lens type Paul Whiteman interferometer time division multiplexer of formation, as shown in figure 15.H1......H4 represents 4 grip assembly cascades among Figure 15.2 covers, 4 covers ..., the 2n cover (n=1,2, ∞) all belong to this patent claimed range.
(2) plate spectro-film with the GRIN Lens of tail optical fiber, the optical fiber grin rod lens type Paul Whiteman fibre optic interferometer time division multiplexer of formation, as shown in figure 16.
Be 4 grades of Paul Whiteman fibre optic interferometer time division multiplexers among upper Figure 16.1 grade, 2 grades ..., the n level (n=1,2, ∞) all belong to this patent claimed range.
Figure 15 and Figure 16 are the Paul Whiteman fibre optic interferometers that consists of with " 1 * 2 " (or " 2 * 1 ") device.Paul Whiteman fibre optic interferometer for being made of " 1 * n " (or " n * 1 ") also belongs to this patent claimed range." 1 * 4 " optical fiber grin rod lens type Paul Whiteman fibre optic interferometer shown in Figure 17 for example.
Embodiment 3:
GRIN Lens adopts the excellent lens with collimated light function of 1/4th pitches.The refraction index profile of GRIN Lens is:
n＝n
0[1-1/2Ar
2] (1)
In the formula, n
0Be the refractive index of axle upper glass, A is distributed constant, and r is radius.
Approximate lower at paraxial meridian, equations of light ray is reduced to
Wherein, x represents light to the vertical range in axle center, and z represents the horizontal level take the incident end as starting point.
To (2) formula integration, and bring boundary condition into and get:
X in the formula
0, θ
0Respectively incident ray height and incidence angle, x
c, θ
cBe emergent ray height and the angle of emergence, L is the distance that optical fiber is walked in the z direction.
Distinguishingly, when the two lens distributed constants that adopt are identical, and length is P/4, i.e. L
1=L
2=p/4 and A
1=A
2During=A (wherein P is pitch), have
So light position and the angle that can from second lens, be penetrated by formula (4):
Namely
If this moment, the Axis centre index of two GRIN Lens was identical, then have
This shows that the light of incident is symmetric relation with respect to optical axis in the light that penetrates in second lens and the first lens.Placed side by side and lens two ends all are connected to optical fiber pigtail with two lens.Owing to be coated with spectro-film, so these lens are a semi-transparent semi-reflecting lens in fact.By adjusting the coating process parameter, can accomplish 1: 1 splitting ratio, by the invertibity of light path, two long is that the lens combination of 1/4th pitches can be combined into two ways of optical signals one road signal.This compound lens consists of a Paul Whiteman interferometer, and its spectro-film is divided into two the light wave fields amplitude.When the incident light pulse repetition rate was 10GHz, 4 Paul Whiteman interferometer series connection had just consisted of collimation light splitting type 160GHz optical time division multiplexer.
The making difficult point of optical time division multiplexer is that accurate delay of control is poor, makes the light pulse of every road be inserted in prime pulse middle, and the 160GHz repetition rate requires pulsion phase every 6.25ps.Specific practice is as follows: choose one road signal as a reference, another road produces with it the delay inequality of Δ Ti.
M=2 wherein, 4,8,16; I=1,2,3,4.Corresponding optical fiber length difference calculates according to following formula:
Wherein C is light transmission speed in a vacuum, and n is the refractive index in fiber cores district.
The time delay adjustment is taked to control fibre optic interferometer and is interfered arm lengths to realize.With optical fiber according to the time delay length requirement with after the cutting of the optical fiber cutter of scale, use the optical fiber splicer welding.Suppose that the original pulse repetition rate is f
0=10GHz, in order to form the repetition rate of 20GHz, the coupling arm light pulse must be inserted in the centre of straight-through arm light pulse.When time delay was adjusted, the relation between the changes delta L of fiber lengths and the pulse shift position Δ t was shown in (8) formula, and wherein Δ L represents the variation of fiber lengths, and Δ t represents the variation of pulse shift position, and c represents the light velocity in the vacuum, is 3 * 10
8M/s, n represent the refractive index of fiber core layer.What use is common G652 monomode fiber, and the sandwich layer refractive index is about 1.443; Calculate like this pulse every mobile 1ps on oscilloscope and need to adjust the about 0.21mm of reflection end fiber lengths.Adopt cleverly fiber cut and fusion techniques, the accurate adjustment time delay.By the method for collimating lens plating spectro-film, guaranteed the consistency of splitting ratio, small difference can be regulated by little flexure stress of optical fiber self, the amplitude of every one-level is adjusted successively, with amplitudes at different levels the assurance after unanimously.In the making, when the oscilloscope bandwidth is inadequate, can't observe the pulse after multiplexing, adopt a cleverly method, when the fourth stage is multiplexing, increase the decay on a certain road in the two-way, make it to be converted into the light pulse of on oscilloscope, observing respectively two-way 80GHz, then can reach the purpose of equivalent observation 160GHz light pulse, shown in Figure 18,19.
Waveform above the oscilloscope is the 1st, 3,5 of 160GHz pulse, ..., the 15 tunnel, following waveform is the 2nd of 160GHz pulse, 4,6 ..., 16 the tunnel, show Δ=6.243ps among the figure, so the adaptive multiplexer precision that adopts fiber cut welding mode to make is 0.007ps, namely be better than 1.5 μ m, satisfy the 160Gb/s transmission requirement fully.
After the time delay adjustment is finished, adopt the optical fiber splicer welding with fused fiber splice, and add heat-seal with heat-shrink tube.
Claims (3)
1. optical time division multiplexer is characterized in that:
Consisted of by multistage Paul Whiteman interferometer, the spectro-film of placing 1: 1 splitting ratio between a pair of fiber collimating lenses consists of optical fiber lens type light-splitting device, spectro-film does not change phase place for a minute amplitude type, a minute light time, and two above-mentioned optical fiber lens type light-splitting devices consist of the one-level of Paul Whiteman interferometer; Every grade of Paul Whiteman interferometer is by optical fiber pigtail, GRIN Lens, and spectro-film consists of; Optical fiber pigtail and GRIN Lens coupling consist of fiber collimating lenses; Plate spectro-film at the fiber collimating lenses end face;
Input signal enters the light-splitting device that is made of the GRIN Lens plating spectro-film with tail optical fiber and is divided into two, one tunnel reflection, one Reuter penetrates, reflection and transmission signal move ahead along two arms that optical fiber consists of, optical fiber two arm lengths are adjusted to and are satisfied the signal frequency multiplication requirement, when arriving the light-splitting device of another Opposite direction connection, synthesize one road signal;
The the 1 road and the 2 tunnel optical fiber length difference DL
iSatisfy:
Wherein c is light transmission speed in a vacuum; N is the refractive index in fiber cores district; Footmark i is the rank of Paul Whiteman interferometer, i=1,2,3,4......;
M=2
i, T
0Be the pulse repetition period before the time division multiplexing; Every one-level Paul Whiteman interferometer according to
Adjust the 1 road and the 2 tunnel optical fiber length difference DL
i, light signal speed is doubled;
The connected mode of every one-level Paul Whiteman interferometer and next stage Paul Whiteman interferometer is for connecting; The fiber lengths no requirement (NR) is in series by multistage Paul Whiteman interferometer, and n level Paul Whiteman interferometer can be brought up to light signal speed 2 of original speed
nDoubly, n=1,2,3,4.......
2. a kind of optical time division multiplexer according to claim 1 is characterized in that: with the GRIN Lens plating spectro-film of tail optical fiber, and splitting ratio 1: 1, spectro-film is in the smooth light splitting in wave-length coverage broadband greater than 100nm.
3. a kind of optical time division multiplexer according to claim 1 and 2, it is characterized in that: fiber end face is fired into lens shape, and light is become directional light.
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| CN101846577B (en) * | 2010-06-18 | 2014-11-26 | 珠海保税区光联通讯技术有限公司 | Passive optical fiber sensor and optical fiber detection system |
| CN103884401B (en) * | 2014-03-31 | 2017-03-08 | 武汉理工大学 | The detection means of optical fiber oil water surface and detection method |
| CN109341520A (en) * | 2018-10-31 | 2019-02-15 | 威海北洋电气集团股份有限公司 | The measuring device and method of fibre optic interferometer arm length difference based on white light interference |
| CN109901341B (en) * | 2019-04-10 | 2022-02-11 | 曲阜师范大学 | Broadband optical fiber collimator-based pre-splitting Mach-Zehnder interferometer and method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0697775A2 (en) * | 1994-08-15 | 1996-02-21 | Nippon Telegraph And Telephone Corporation | Multiple-channel all-optical TDM-WDM converter and multiple-channel all-optical TDM demultiplexer |
| GB2441410A (en) * | 2006-08-09 | 2008-03-05 | George Zarris | Time multiplexed space switch which translates a single wavelength data pulse sequence into a sequence of multi-wavelength pulses |
| CN101212273A (en) * | 2006-12-28 | 2008-07-02 | 中国科学院半导体研究所 | 8-channel optical time division multiplex signal production system |
| CN101296051A (en) * | 2008-06-12 | 2008-10-29 | 上海交通大学 | Multilevel light time-division multiplexer with three as base number |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0697775A2 (en) * | 1994-08-15 | 1996-02-21 | Nippon Telegraph And Telephone Corporation | Multiple-channel all-optical TDM-WDM converter and multiple-channel all-optical TDM demultiplexer |
| GB2441410A (en) * | 2006-08-09 | 2008-03-05 | George Zarris | Time multiplexed space switch which translates a single wavelength data pulse sequence into a sequence of multi-wavelength pulses |
| CN101212273A (en) * | 2006-12-28 | 2008-07-02 | 中国科学院半导体研究所 | 8-channel optical time division multiplex signal production system |
| CN101296051A (en) * | 2008-06-12 | 2008-10-29 | 上海交通大学 | Multilevel light time-division multiplexer with three as base number |
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