CN103743551B - Method for measuring optical performance of multi-functional lithium niobate integrator - Google Patents
Method for measuring optical performance of multi-functional lithium niobate integrator Download PDFInfo
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Abstract
The invention belongs to the techical field of measurement of optical devices, in particular to a method for measuring optical performance of multi-functional lithium niobate integrator. The method includes the steps of: measuring a waveguide device inputting the length of a tail polarization-maintaining fiber; measuring the length waveguide chips; measuring the waveguide device outputting the length of a tail polarization-maintaining fiber; aiming at conveying axises of input/output a tail fiber slow axis and the waveguide chip; gaining the result of measuring a first distributed polarization crosstalk; changing the light injecting condition of the waveguide device; gaining the result of measuring a second distributed polarization crosstalk; through analyzing and calculating the data, gaining the optic parametric of the waveguide device. The method can not only exactly gain the extinction ratio of the waveguide chips and the linear birefringence, but also gain a coupling crosstalk and the linear birefringence of the chip waveguide fiber input/output end, an input/output extend fiber solder joint, and an optical defect inside of the waveguide chip and the connecting tail fiber, thereby decreasing the difficulty of reading and analyzing the signal, and simplifying the process of analyzing and managing the data.
Description
Technical field
The invention belongs to optics field of measuring technique is and in particular to arrive a kind of light of multi-functional Lithium metaniobate integrated device
Learn performance measurement method.
Background technology
Fiber optical gyroscope is commonly called as " Y waveguide ", typically adopts niobic acid lithium material as substrate, and it is by single mode light wave
Lead, beam splitter, photomodulator and optical polarizator have carried out highly integrated, are composition interference optical fiber top (FOG) and light
The core devices of fiber current mutual inductor, decide certainty of measurement, stability, volume and the cost of optical fiber sensing system.
Waveguide chip extinction ratio is the Important Parameters of Y waveguide device, such as：Use in high accuracy micron order optical fibre gyro
Y waveguide, its chip extinction ratio requires to reach more than 80dB.For example：No.44 Inst., China Electronical Science and Technology Group Co.
A kind of method (the CN of raising extinction ratio of Y-waveguide chip for fiber-optic gyroscope that Hua Yong, Shu Ping et al. propose
201310185490.2), waveguide chip extinction ratio is brought up to more than 80dB.But it is limited to test instrunment performance and test
Method, also cannot realize High Extinction Ratio Y waveguide chip extinction ratio at present and accurately measure.Conventional polarization property detecting instrument
Extinction ratio tester, dBm Optics company of the resolution highest U.S. develops Model4810 type polarization extinction ratio measuring instrument
Only 72dB, in addition, the ERM102 type of General Photonics company of the U.S., Fiberpro company of Korea S
ER2200 type, the PEM-330 type highest extinction ratio of Japanese Santec company all can only achieve 50dB about it is impossible to meet 80dB with
The testing requirement of upper High Extinction Ratio Y waveguide device.
Alfred Healy of Fibersense Technology Corporation company of the U.S. in 2002 et al. is open
A kind of coupling process (US6870628) of the input/output optical fiber of integrated waveguide chip, is realized using white light interferometry method
The measurement of the coupling cross-talk of waveguide chip input/output optical fiber；Yi little Su, Xiao Wen of BJ University of Aeronautics ＆ Astronautics in 2004 etc.
People discloses a kind of optical fibre gyro integrated optical modulator on-line testing method and its test device (CN
200410003424.X), it is possible to achieve the measurement of the optical parametric such as the loss of device, splitting ratio；Beijing Aviation space flight in 2007
Yi little Su, Xu little Bin of university et al. disclose a kind of Y waveguide chip and polarization maintaining optical fibre online to shaft device and its countershaft online
Method (CN 200710064176.3), equally achieves waveguide chip and waveguide input/output optical fiber string using interferometric spectrometry
The measurement of sound.Above-mentioned patent does not all design the measurement of waveguide chip extinction ratio.
Y waveguide is made up of input optical fibre, waveguide chip and output optical fibre three part, and traditional extinction ratio test is lump
Formula measures, and can only obtain the overall extinction ratio numerical value of Y waveguide device, i.e. device all of extinction ratio sum, waveguide chip delustring
It has been submerged among the extinction ratio (30～40dB) that optical fiber pigtail is coupled with chip it is impossible to obtain disappearing of chip than (50～80dB)
Light ratio.Therefore, the measurement difficult point of Y waveguide device chip extinction ratio mainly has：1) white light interferometer based on Low coherence principle can
To realize the measurement of distributed polarization cross-talk, can to the measurement of Y waveguide device parameters (include chip extinction ratio), but how
The resolution of polarization crosstalk can be brought up to more than -90dB, realize extinction ratio is up to the measurement of more than 80dB waveguide chip；
2) in order to improve spatial resolution, the wider SLD light source of the commonly used spectrum of white light interferometer, but light source light spectrum ripple
(ripple) relevant peak will be caused, its corresponding polarization crosstalk amplitude is about between -50～-70dB, if waveguide chip
Polarization crosstalk peak value overlaps, then chip extinction ratio is easily flooded wherein, and how to eliminate its impact is to need to compel cut-grafting solution
Problem certainly；3) waveguide device, as an assembly, accurately distinguishing of each crosstalk signal forming such as chip, tail optical fiber, has phase
When difficulty, how to accurately identify white light interference signal is one of difficult point of device detection.
The invention discloses a kind of optical property measuring method of multi-functional lithium niobate integrated optical device (Y waveguide), bag
The length including waveguide device input/output tail optical fiber selects to select with measurement, waveguide device light injection condition, waveguide chip geometric parameters
The steps such as the measurement of number, the distributed polarization cross talk characteristic measurement of waveguide device, and the calculating of waveguide device optical performance parameter,
It is characterized in that, using white light interferometer (or low-coherence measuring device), in the input/output terminal of tested integrated waveguide device, passing through
Extend the length of input/output terminal tail optical fiber, the presetting angle of the input/output detection light being injected in device under test is entered simultaneously
Row sets, respectively the polarization crosstalk Noise Background data of measurement apparatus and the distributed polarization cross-talk data of device；By to two
The contrast of person, it is possible to obtain some polarizations being introduced by waveguide chip, waveguide input/output tail optical fiber, input/output extended fiber
Cross-talk characteristic peak；Using the measurement data to waveguide device geometrical length, including：The length of input/output extended fiber, waveguide
Input/output tail optical fiber length and waveguide chip length, can be calculated waveguide device chip delustring, chip linear birefrigence,
Multiple optical parametrics such as the coupling cross-talk of waveguide input/output terminal tail optical fiber, input/output extended fiber solder joint.The method eliminates
The impact to measurement for the light source light spectrum ripple, improves the accuracy of measurement, it is possible to achieve the super large extinction ratio device of 0～85dB
The measurement of performance, has the advantages that high spatial resolution, can be widely used for the integrated optics device in more than 85dB for the chip extinction ratio
With the presence or absence of identification and the analysis of optical defect inside the quantitative assessment of part, and waveguide chip and connection tail optical fiber.
Content of the invention
It is an object of the invention to provide a kind of eliminate light source light spectrum ripple to measurement impact, realize waveguide chip with
The countershaft automatic identification of tail optical fiber, improves the optical property measuring method of the multi-functional Lithium metaniobate integrated device of accuracy of test.
The object of the present invention is achieved like this：
(1) length l of inclined tail optical fiber is protected in the input of measurement waveguide deviceW-i, detection transmission is between the input inclined tail optical fiber fast and slow axis of guarantor
Optical path difference S of light waveW-iThe light path S at the relevant peak whether producing more than light source light spectrum rippleripple, that is,
SW-i>Sripple,
SW-i=lW-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber；
(2) if length l of inclined tail optical fiber is protected in inputW-iIt is unsatisfactory for the condition in step (1), then protect on inclined tail optical fiber in input
One section of input of welding extends polarization maintaining optical fibre, and the countershaft angle of solder joint is 0 ° -0 °, and length is lf-iInput to extend polarization maintaining optical fibre full
Sufficient optical path difference Sf-iThe light path S at the relevant peak producing more than light source light spectrum rippleripple, that is,
Sf-i>Sripple
Sf-i=lf-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber, measure and record the length that input extends polarization maintaining optical fibre
Degree lf-i；
(3) measure length l of waveguide chipW；
(4) length l of inclined tail optical fiber is protected in the output of measurement waveguide deviceW-o, detection transmission is between the output inclined tail optical fiber fast and slow axis of guarantor
Optical path difference S of light waveW-oWhether more than optical path difference S transmitting light wave between waveguide chip fast and slow axisW, that is,
SW-o>SW, SW-o=lW-o×Δnf, SW=lW×ΔnW, Δ nWThe linear birefrigence of waveguide chip；
(5) if length l of inclined tail optical fiber is protected in outputW-oIt is unsatisfactory for the condition of step (4), then protect in output and weld on inclined tail optical fiber
Connect one section of output and extend polarization maintaining optical fibre, the countershaft angle of solder joint is 0 ° -0 °, and length is lf-oOutput extend polarization maintaining optical fibre light
Path difference Sf-oSf-o>SW, Sf-o=lf-o×Δnf, measure and record length l that output extends polarization maintaining optical fibref-o；
(6) slow axis of inclined tail optical fiber and the transmission axle of waveguide chip are protected in be aligned input or output, and no input extends polarization maintaining optical fibre
When, the countershaft angle, θ that inclined tail optical fiber exports the tail optical fiber of the polarizer with white light interferometer is protected in input1For 0 ° -0 °；There is input to extend to protect partially
During optical fiber, input extends the countershaft angle, θ that polarization maintaining optical fibre exports the tail optical fiber of the polarizer with white light interferometer1Also it is 0 ° -0 °；No defeated
When going out to extend polarization maintaining optical fibre, the countershaft angle, θ that inclined tail optical fiber inputs the tail optical fiber of analyzer with white light interferometer is protected in output2For 0 ° -0 °；
When having output to extend polarization maintaining optical fibre, output extends the countershaft angle, θ that polarization maintaining optical fibre inputs the tail optical fiber of analyzer with white light interferometer2
Also it is 0 ° -0 °；
Be aligned input or the transmission axle of the output inclined tail optical fiber fast axle of guarantor and waveguide chip, inclined tail optical fiber or input prolongation are protected in input
Polarization maintaining optical fibre exports the countershaft angle, θ of the tail optical fiber of analyzer with white light interferometer1For 0 ° -90 °；Inclined tail optical fiber or output are protected in output
Extend the countershaft angle, θ that polarization maintaining optical fibre inputs the tail optical fiber of analyzer with white light interferometer2For 90 ° -0 °；
(7) obtain first time distributed polarization crosstalk measurement result, i.e. the instrument polarization cross-talk noise basis of white light interferometer
Truth of a matter evidence, its abscissa is scanning light path numerical value S, unit：μm, vertical coordinate is polarization crosstalk amplitude E, unit：dB；The light of measurement
Journey sweep limitss Δ S
ΔS>2(Sf-i+SW-i+SW+SW-o+Sf-o)
And, the midpoint of light path sweep limitss is the position of the peak-peak of polarization crosstalk measurement data；
(8) convert the light injection condition of waveguide device：When no input extends polarization maintaining optical fibre, input is protected inclined tail optical fiber and is done with white light
Interferometer inputs the countershaft angle, θ of the tail optical fiber of the polarizer1For 0 ° -45 °；When having input to extend polarization maintaining optical fibre, input extends protects polarisation
Input the countershaft angle, θ of the tail optical fiber of the polarizer with white light interferometer1Also it is 0 ° -45 °；When no output extends polarization maintaining optical fibre, output
Protect the countershaft angle, θ that inclined tail optical fiber exports the tail optical fiber of analyzer with white light interferometer2For 45 ° -0 °；Output is had to extend polarization maintaining optical fibre
When, output extends the countershaft angle, θ of polarization maintaining optical fibre and tail optical fiber2Also it is 45 ° -0 °；
(9) second distributed polarization crosstalk measurement result, i.e. the optical polarization crosstalk measurement data of device, its light are obtained
The requirement of journey sweep limitss Δ S is identical with step (7)；
(10) by the analysis of data and calculating, obtaining chip delustring, the linear birefrigence of chip of waveguide device, ripple
Lead the coupling cross-talk of input/output terminal tail optical fiber, the linear birefrigence optical parameter of tail optical fiber：
(10.1) the device distributed polarization crosstalk measurement result obtaining measuring process (9) is white with what step (7) obtained
The instrument polarization cross-talk background data of optical interferometer is contrasted, it is possible to obtain some by waveguide chip, waveguide input or export
Protect inclined tail optical fiber, input or output and extend the polarization crosstalk characteristic peak that polarization maintaining optical fibre introduces, the abscissa of peak value corresponds to optical path difference S,
Unit：μm, amplitude E of the corresponding polarization crosstalk of vertical coordinate, unit：dB；
(10.2) extend length l of polarization maintaining optical fibre according to inputf-iNumerical value, is calculated the reason that input extends polarization maintaining optical fibre
By optical path delay numerical value SF-i (theoretical), SF-i (theoretical)=lf-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter；Device polarization crosstalk is tested
In data, determination meets optical path delay amount S by what the solder joint of input prolongation polarization maintaining optical fibre and the input inclined tail optical fiber of guarantor causedF-i (theoretical)'s
Polarization crosstalk peak value, its Y value corresponds to solder joint cross-talk value Ef-i, it is real that abscissa corresponds to input prolongation polarization maintaining optical fibre
Optical path delay amount SF-i (measures)；
(10.3) length l protecting inclined tail optical fiber is inputted according to waveguideW-iNumerical value, is calculated the reason that inclined tail optical fiber is protected in waveguide input
By optical path delay numerical value SW-i (theoretical), SW-i (theoretical)=lW-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter；In device test data,
Determine and meet optical path delay amount S by what the input inclined tail optical fiber sound of guarantor causedF-i (measures)+SW-i (theoretical)Polarization crosstalk peak value, its vertical coordinate
Coupling cross-talk value EW-i, abscissa real optical path delay amount S of correspondenceF-i (measures)+SW-i (measures)；
(10.4) length l of polarization maintaining optical fibre is inputted according to waveguideW-iWith its corresponding true optical path delay amount SW-i (measures), can
To be accurately calculated the linear birefrigence Δ n that waveguide inputs polarization maintaining optical fibreF-i (measures),
ΔnF-i (measures)=SW-i (measures)/lW-i
(10.5) with step 2)～step 4) identical, extend length l of polarization maintaining optical fibre according to outputf-o, waveguide output protects partially
Tail optical fiber length lW-o, determine that output extends polarization maintaining optical fibre and solder joint cross-talk value E of inclined tail optical fiber is protected in outputf-o, output optical fibre and waveguide
Power coupling cross-talk value E of chipW-o, and the linear birefrigence Δ n of waveguide output polarization maintaining optical fibreW-o；
ΔnW-o (measures)=SW-o (measures)/lW-o
(10.6) length l according to waveguide chipW, it is calculated that waveguide chip is fast, the optical path delay amount between slow axis
SW (theoretical), SW (theoretical)=lW×ΔnW (theoretical), linear birefrigence Δ nW (theoretical)By 8 × 10-2Meter；In device polarization crosstalk test data
In, inclined tail optical fiber can be protected in input, input extends polarization maintaining optical fibre, inclined tail optical fiber is protected in output, output extends polarization maintaining optical fibre and waveguide core
Piece is fast, produce light path sum S between slow working shaftF-i (measures)+SW-i (measures)+SW (theoretical)+SW-o (measures)+SF-o (measures)Or the difference of light path
SF-i (measures)+SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (theoretical)At corresponding abscissa, find the polarization crosstalk peak of waveguide chip
Value, its amplitude EWAbsolute value be waveguide chip extinction ratio；Waveguide chip cross-talk peak value occurs in light path sum SF-i (measures)+
SW-i (measures)+SW (measures)+SW-o (measures)+SF-o (measures)Place is it may be determined that the fast axle of waveguide tail optical fiber is aligned with waveguide fast axle, and occurs in light
Difference S of journeyF-i (measures)+SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (theoretical)Then determine that the slow axis of waveguide tail optical fiber is aligned with waveguide fast axle；Root
Optical path delay amount S of the waveguide chip obtaining according to measurementW (measures)Actual length l with waveguide chipW, it is calculated waveguide chip
Linear birefrigence Δ nW (measures)
ΔnW (measures)=SW (measures)/lW.
The beneficial effects of the present invention is：
The method not only can obtain the extinction ratio of waveguide chip and linear birefrigence exactly additionally it is possible to obtain core simultaneously
The coupling cross-talk of piece waveguide input/output terminal tail optical fiber, linear birefrigence, input/output extended fiber solder joint, and waveguide chip
With connection tail optical fiber internal optical defect；The method allows by the selection to input/output fiber lengths, dexterously avoids width
Spectrum light source light spectrum ripple (ripple) causes the impact to measurement for the relevant peak, increased realizability and stability；The method can
By the polarization crosstalk data of comparative device and the cross-talk noise background of measurement apparatus, to make to treat waveguide chip, input/output tail
The polarization crosstalk peak value of the generations such as fibre, extended fiber solder joint is more prone to differentiate, and reduces the difficulty of signal-obtaining and identification, letter
Data analysiss and the process processing are changed, it is possible to achieve the measurement of extinction ratio 85dB above integrated waveguide device.
Brief description
Fig. 1 is the method for testing flow chart of the optical parameters such as the chip extinction ratio of Y waveguide device；
Fig. 2 is the Y waveguide device detection schematic diagram based on white light interferometric device；
Fig. 3 is to treat that 0 °～45 ° of input between side device and test device is directed at, exports the schematic diagram of 45 °～0 ° be aligned；
Fig. 4 is to treat that 0 °～0 ° of input between side device and test device is directed at, exports the schematic diagram of 0 °～0 ° be aligned；
Fig. 5 is that waveguide tail optical fiber slow axis is aligned with waveguide chip fast axle, and when 0 °～0 ° of device accesses test device, measurement obtains
Distributed polarization cross-talk data (the polarization interference noises of measurement apparatus)；
Fig. 6 is that waveguide tail optical fiber slow axis is aligned with waveguide chip fast axle, 0 °～45 ° of the input of device, 45 °～0 ° access of output
During measurement apparatus, measure the distributed polarization cross-talk data (optical characteristics of Y waveguide device) obtaining；
Fig. 7 is that waveguide tail optical fiber fast axle is aligned with waveguide chip fast axle, 0 °～90 ° of device, 90 °～0 ° access test device
When, measure the distributed polarization cross-talk data (the polarization interference noises of measurement apparatus) obtaining；
Fig. 8 is that waveguide tail optical fiber fast axle is aligned with waveguide chip fast axle, 0 °～45 ° of the input of device, 45 °～0 ° access of output
During measurement apparatus, measure the distributed polarization cross-talk data (optical characteristics of Y waveguide device) obtaining.
Specific embodiment
Multi-functional lithium niobate integrated optical device (Y waveguide) based on white light interferometer measurement apparatus proposed by the present invention
Optical property measuring method, is uniformly injected into flashlight in the fast axle of the inclined tail optical fiber of guarantor of waveguide device and slow axis, respectively by surveying
The white light interference signal amplitude of amount waveguide device transmission axle (fast axle) and cut-off axle (slow axis) and transmission axle itself interference signal width
Ratio between degree, obtains the optical parametrics such as waveguide chip extinction ratio, waveguide coupling cross-talk；Measuring process, comprises waveguide device
The length of input/output tail optical fiber selects and measurement, the measurement of waveguide chip geometric parameter, waveguide device light injection condition select,
The distributed polarization cross talk characteristic measurement of waveguide device, and the calculating of waveguide device optical performance parameter, detailed process such as accompanying drawing 1
Shown：
1) length l of inclined tail optical fiber 21 is protected in the input of measurement waveguide deviceW-iIt is desirable to transmission protects inclined tail optical fiber 21 fast and slow axis in input
Between light wave optical path difference SW-i(SW-i=lW-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber) it is more than wide spectrum light source 11 spectrum
The light path S at the relevant peak that ripple producesripple, that is, meet
SW-i>Sripple(1)
2) if length l of inclined tail optical fiber 21 is protected in inputW-iIt is unsatisfactory for (1) formula, then one section of input of welding extends polarization maintaining optical fibre
25 it is desirable to the countershaft angle of solder joint 24 is 0 ° -0 °, the fiber lengths l of extended fiber 25 simultaneouslyf-iNeed to meet optical path difference Sf-i
(Sf-i=lf-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber) it is more than the relevant peak that wide spectrum light source 11 spectrum ripple produces
Light path Sripple, that is, meet
Sf-i>Sripple(2)
Measure and record length l that input extends polarization maintaining optical fibre 25f-i；
3) measure length l of waveguide chip 22W；
4) length l of inclined tail optical fiber 23 is protected in the output of measurement waveguide deviceW-oIt is desirable to transmission protects inclined tail optical fiber 23 fast and slow axis in output
Between light wave optical path difference SW-o(SW-o=lW-o×Δnf) more than the optical path difference transmitting light wave between waveguide chip 22 fast and slow axis
SW(SW=lW×ΔnW, Δ nWThe linear birefrigence of waveguide chip), that is, meet
SW-o>SW(3)
5) if length l of inclined tail optical fiber 23 is protected in outputW-o3 formulas that are unsatisfactory for require, then one section of output of welding extends polarization maintaining optical fibre
27；The countershaft angle requiring solder joint 26 is 0 ° -0 °, length l simultaneouslyf-oOutput extends optical path difference S of polarization maintaining optical fibre 27f-o(Sf-o=
lf-o×Δnf) need meet
Sf-o>SW(4)
Measure and record length l that output extends polarization maintaining optical fibre 27f-o；
6), when testing waveguide device first, the transmission axle of inclined tail optical fiber 21,23 slow axis and waveguide chip 22 is protected in its input/output
(fast axle) to punctual, the light injection condition of device should meet：When no input extends polarization maintaining optical fibre 25, input protect inclined tail optical fiber 21 with
White light interferometer exports the countershaft angle, θ of the tail optical fiber 16 of the polarizer 151For 0 ° -0 °；When having input to extend polarization maintaining optical fibre 25, input
Extend the countershaft angle, θ of polarization maintaining optical fibre 25 and tail optical fiber 161Also it is 0 ° -0 °；When no output extends polarization maintaining optical fibre 27, inclined tail is protected in output
Fibre 23 and the countershaft angle, θ of tail optical fiber 312For 0 ° -0 °；When having output to extend polarization maintaining optical fibre 27, output extends polarization maintaining optical fibre 27 and tail
Fine 31 countershaft angle, θ2Also it is 0 ° -0 °；
The transmission axle (fast axle) of its input/output tail optical fiber 21,23 fast axles and waveguide chip 22 is to punctual, the light injection of device
Condition should meet：The countershaft angle, θ of inclined tail optical fiber 21 or extended fiber 25 and tail optical fiber 16 is protected in input1For 0 ° -90 °；Output is protected
Tail optical fiber 23 or the countershaft angle, θ inputting extended fiber 27 and tail optical fiber 31 partially2For 90 ° -0 °；
7) start white light interferometer, obtain first time distributed polarization crosstalk measurement result, the i.e. instrument of white light interferometer
Polarization crosstalk Noise Background data, its abscissa is scanning light path numerical value S (unit：μm), vertical coordinate is polarization crosstalk amplitude E
(unit：dB)；The light path sweep limitss Δ S of measurement needs to meet
ΔS>2(Sf-i+SW-i+SW+SW-o+Sf-o) (5)
And, the midpoint of light path sweep limitss is chosen as the position of the peak-peak of polarization crosstalk measurement data as far as possible.
8) convert the light injection condition of waveguide device：When no input extends polarization maintaining optical fibre 25, input protect inclined tail optical fiber 21 with white
Optical interferometer exports the countershaft angle, θ of the tail optical fiber 16 of the polarizer 151For 0 ° -45 °；When having input to extend polarization maintaining optical fibre 25, input
Extend the countershaft angle, θ of polarization maintaining optical fibre 25 and tail optical fiber 161Also it is 0 ° -45 °；When no output extends polarization maintaining optical fibre 27, output is protected partially
Tail optical fiber 23 inputs the countershaft angle, θ of the tail optical fiber 31 of analyzer 32 with white light interferometer1For 45 ° -0 °；Output is had to extend polarization maintaining optical fibre
When 27, output extends the countershaft angle, θ of polarization maintaining optical fibre 27 and tail optical fiber 312Also it is 45 ° -0 °；
9) start white light interferometer, obtain second distributed polarization crosstalk measurement result, i.e. the optical polarization string of device
Sound measurement data, the requirement of its light path sweep limitss Δ S and step 7) identical；
10) if it is known that the polarization crosstalk background data of white light interferometer, measuring process 6 can be skipped over) and 7) directly obtain
Instrument optical polarization crosstalk measurement data, by the analysis of data and calculating, can disposably obtain waveguide device
Chip delustring, the linear birefrigence of chip, the coupling cross-talk of waveguide input/output terminal tail optical fiber, linear birefrigence of tail optical fiber etc.
Optical parameter.
Input is protected inclined tail optical fiber 21, the output inclined tail optical fiber 23 of guarantor and prolongation polarization maintaining optical fibre 25, is extended the length choosing of polarization maintaining optical fibre 27
Select foundation, it is characterized in that：Inclined tail optical fiber 21 is protected in input, the length selection gist of the output inclined tail optical fiber 23 of guarantor can be exchanged, and prolongs accordingly
Long polarization maintaining optical fibre 25, the length selection gist of prolongation polarization maintaining optical fibre 27 are also required to exchange simultaneously.
The chip delustring of waveguide device, the linear birefrigence of chip, the coupling cross-talk of waveguide input/output terminal tail optical fiber, tail
The calculation procedure of fine linear birefrigence is：
1) by measuring process 9) the device distributed polarization crosstalk measurement result that obtains and step 7) obtain (or known)
The instrument polarization cross-talk background data of white light interferometer is contrasted, it is possible to obtain some by waveguide chip, waveguide input/output
The polarization crosstalk characteristic peak that tail optical fiber, input/output extended fiber introduce, the abscissa of peak value corresponds to optical path difference S (unit：μm),
Amplitude E (the unit of the corresponding polarization crosstalk of vertical coordinate：dB)；
2) input extends length l of polarization maintaining optical fibre 25f-iNumerical value, can be calculated the reason that input extends polarization maintaining optical fibre 25
By optical path delay numerical value SF-i (theoretical)(SF-i (theoretical)=lf-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter)；Device polarization crosstalk is surveyed
It may be determined that meeting optical path delay amount S in examination dataF-i (theoretical)Polarization crosstalk peak value be by input extend polarization maintaining optical fibre 25 with defeated
The solder joint 24 entering to protect inclined tail optical fiber 21 causes, and its Y value corresponds to solder joint 24 cross-talk value Ef-i, abscissa correspond to postpone optical fiber
Real optical path delay amount SF-i (measures)；
3) length l protecting inclined tail optical fiber 21 is inputted according to waveguideW-iNumerical value, can be calculated waveguide input and protect inclined tail optical fiber 21
Theoretical optical path delay numerical value SW-i (theoretical)(SW-i (theoretical)=lW-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter)；Device detection number
According in it may be determined that meeting optical path delay amount SF-i (measures)+SW-i (theoretical)Polarization crosstalk peak value be that inclined tail optical fiber 21 and ripple are protected by input
The power coupling cross-talk leading chip 22 causes, and its vertical coordinate couples cross-talk value EW-i, the abscissa real optical path delay amount of correspondence
SF-i (measures)+SW-i (measures)；
4) length l protecting inclined tail optical fiber 21 is inputted according to waveguideW-iWith its corresponding true optical path delay amount SW-i (measures), permissible
Accurately it is calculated the linear birefrigence Δ n that inclined tail optical fiber 21 is protected in waveguide inputF-i (measures), it is determined by (6) formula：
ΔnF-i (measures)=SW-i (measures)/lW-i(5)
5) with 2)～4) step is similar, extends length l of polarization maintaining optical fibre 27 according to outputf-o, waveguide output protect inclined tail optical fiber 23
Length lW-oIt may be determined that output extends polarization maintaining optical fibre (27) and solder joint 26 cross-talk value E of inclined tail optical fiber 23 is protected in outputf-i, output protect
Tail optical fiber 23 partially couples cross-talk value E with the power of waveguide chip 22W-o, and the linear birefrigence Δ of the waveguide output inclined tail optical fiber 23 of guarantor
nf-o；
ΔnF-o (measures)=SW-o (measures)/lW-o(6)
6) length l according to waveguide chip 22W, can be calculated that it is fast, optical path delay amount S between slow axisW (theoretical)
(SW (theoretical)=lW×ΔnW (theoretical), linear birefrigence Δ nW (theoretical)By 8 × 10-2Meter)；In device polarization crosstalk test data, can
To protect inclined tail optical fiber 21 in input, input extends polarization maintaining optical fibre 25, inclined tail optical fiber 23 is protected in output, output extends polarization maintaining optical fibre 27 and waveguide
Chip 22 is fast, produce optical path difference sum (S between slow working shaftF-i (measures)+SW-i (measures)+SW (theoretical)+SW-o (measures)+SF-o (measures)) or light
Difference (the S of journeyF-i (measures)+SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (theoretical)) corresponding to abscissa at, find the inclined of waveguide chip 22
Cross-talk of shaking peak value, its amplitude EWAbsolute value be waveguide chip 22 extinction ratio；Waveguide chip 22 cross-talk peak value occurs in
State light path sum (SF-i (measures)+SW-i (measures)+SW (measures)+SW-o (measures)+SF-o (measures)) place is it may be determined that the fast axle of waveguide tail optical fiber and waveguide
Fast axle is aligned, and occurs in the difference (S of above-mentioned light pathF-i (measures)+SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (measures)) then determine waveguide tail
Fine slow axis is aligned with waveguide fast axle；Optical path delay amount S of the waveguide chip 22 being obtained according to measurementW (measures)With waveguide chip 22
Actual length lW, can accurately be calculated the linear birefrigence Δ n of waveguide chip 22W (measures)
ΔnW (measures)=SW (measures)/lW(7)
The optical property of a kind of multi-functional lithium niobate integrated optical device (Y waveguide) based on white light interferometer measurement apparatus
Measuring method, its test philosophy is as shown in Figure 2.The detection light being sent by light source module 1 through device under test 2, with device
The flashlight of optical signature is admitted in white light measurement apparatus 3, by means of photodetection, processing module 4, can disposably obtain
Obtain multiple optical parameter such as waveguide chip extinction ratio, linear birefrigence.The concrete function of measurement apparatus is：
Wide spectrum light source 11 sends the fiber coupler 12 that flashlight is through 2/98, and 2% power is fed to photodetection
Device (PD0) 13, for detecting light source power, remaining is exported by white light interferometer 98% after fibre optic isolater (ISO) 14
Device (LP) 15 is changed into the wide range polarized light of high stable partially, through the output tail optical fiber 16 of the polarizer, by the 1st fiber rotation connector
17, detection light is injected in waveguide device 2 to be measured；
Waveguide device 2 is at least made up of input optical fibre, waveguide chip and output optical fibre 3 part, some present in device
Optics discontinuity point, including：In waveguide chip, optical fiber and waveguide Coupling point, optical fiber solder joint, and other waveguides inside and optical fiber
The defect in portion etc., can make transmission one of the signal light energy of a feature axis (such as fast axle) in treating side integrated optical device
Divide and be coupled in orthogonal another one feature axis (such as slow axis), form a series of coupled light beam, the intensity of coupled light beam
Correspond with the optical property of light path position and device.
Above-mentioned coupled light beam exports white light measurement dress together with remaining transmitting beam by the 2nd fiber rotation connector 30
Put in 3, because optical fiber and lithium niobate waveguides have linear birefrigence, the refractive index official post transmission light of presence between two feature axis
With coupling light occur on light path discrete；Above-mentioned light beam through white light interferometer input analyzer 32 polarization polarization after, by light
Fine bonder 33 is divided evenly into two parts respectively, and the half transmission of energy, in the reference arm of optical fiber 34 composition, reaches optical fiber
Bonder 38；The other half transmission of energy is being made up of fiber optical circulator 35, GRIN Lens 36 and mobile mirror 37
In scan arm, same reach fiber coupler 38 and reference arm light beam white light interference signal, by the 2nd, the 3rd photodetector 391,
392 receive and convert optical signals to the signal of telecommunication.This signal, after signal demodulating circuit 41 process, sends into metering computer 42
In；In addition metering computer 42 also will be responsible for controlling mobile mirror 37 to realize light path scanning.
When the mobile mirror 37 of M-Z interferometer carries out light path scanning, generation light path mates with coupling light to make transmission light, will
Produce white light interference signal, the amplitude of its peak amplitude corresponding coupling light；Light path difference pair between white light interference signal peak
The locus of light generation should be coupled, therefore by coupling light white light interference signal intensitys a series of in waveguide device and light path
The detection of position, it is possible to obtain the measurement of the optical characteristics such as device inside extinction ratio, optical fiber Coupling point, optical fiber solder joint.
As shown in figure 3, when the alignment angle of waveguide device to be measured 2 and wide spectrum light source and white light measurement apparatus 3 be 0 °～
45 °, 45 °～0 ° to punctual, the amplitude of white light interference signal of acquisition and optical path delay amount, can represent as following formula：
In formula：S represents light path delayed sweep amount, and R (S) is the normalization self-coherence function of wide spectrum light source, and R (0)=1 passes
The white light interference Peak signal amplitude lost, optical path difference is zero；R (S)=0 (S>S0When, S0Coherence length for wide spectrum light source)；
Sf-i、Sf-o、SW-i、SW-o、SWIt is respectively the optical path delay of input/output extended fiber, input/output tail optical fiber and waveguide chip
Amount, when slow axis light path is ahead of fast axle light path, above-mentioned retardation is defined as+；When slow axis light path lags behind fast axle light path, on
State retardation be defined as-, each optical path delay amount can be represented sequentially as：
In formula, lf-i、lf-o、lW-i、lW-o、lWIt is respectively input/output extended fiber, input/output tail optical fiber and waveguide core
The length of piece, Δ nf、ΔnWIt is respectively the linear birefrigence of polarization maintaining optical fibre and waveguide chip；SrippleIt is concerned with for light source light spectrum ripple
The optical path difference of peak value, it is directly proportional to the active area of SLD light source and refractive index length, SiDeposit in white light interference test device 3
The optical path delay amount of interference peak that leads to of other optical defects；ρf-i、ρf-oIt is respectively input extended fiber and waveguide is defeated
Enter the cross-talk amplitude amplitude of the solder joint of solder joint, output extended fiber and waveguide output optical fibre of optical fiber, ρW-i、ρW-o, be respectively ripple
That leads input/output optical fiber and waveguide chip couples cross-talk amplitude amplitude, εchipFor the amplitude amplitude of Y waveguide extinction ratio, ρripple
The coherence peak amplitude leading to for light source light spectrum ripple；ρiOptical defect present in white light interference test device 3 leads to
Interference peak amplitude.
From (8), (9) formula, if it is known that input/output extended fiber, input/output waveguide tail optical fiber and waveguide
The length of chip and its birefringence, are scanned by white light interferometric device light path, in optical path delay amount ± Sf-i、±Sf-o、±
(Sf-i+SW-i)、±(Sf-o+SW-o)、±(Sf-o+SW-o+Sf-i+SW-i+SW) white light interference peak value can be obtained, by amplitude
Calculate, ρ can be obtained with single passf-i、ρf-o、ρW-i、ρW-o、εchipDeng optical parametric.
From (9) formula, only it is difficult to waveguide device and light source light spectrum ripple, test device from light path and cross-talk amplitude
Polarization crosstalk peak value present in 3 is distinguish between, and therefore the latter can produce considerable influence to measurement.Generally, input/defeated
Go out extended fiber solder joint cross-talk, input/output waveguide pigtail coupling cross-talk etc., its amplitude is not over -50dB (corresponding delustring
Than less than 50dB), and the amplitude at the relevant peak that wide spectrum light source spectrum ripple (ripple) produces is between -60～-70dB, because
This, substantially light source will not produce impact to the measurement of above-mentioned parameter；But quite different for waveguide chip extinction ratio, its amplitude is led to
Often all in more than 50dB, higher reaches more than 80dB (corresponding polarization crosstalk is in -80dB), if the interference light path of waveguide chip
(Sf-i+SW-i+SW-o+Sf-o+SW) with the relevant peak of light source light spectrum ripple (wider scope is had on light path domain, usually several
Individual mm) overlap, then can cause to differentiate, because in order to ensure the realizability that measures it is necessary to (or defeated to input optical fibre
Go out optical fiber) length carry out requirement, that is, meet formula (1), or input optical fibre (or output optical fibre) extended, that is, meet public
Formula (2).
Extinction ratio due to waveguide chip to be measured may be up to more than 80dB, in order to each characteristic peaks are determined more accurately
Amplitude and light path position, eliminate light source light spectrum ripple, other optic fibre light path defects of white light interference test device to measurement shadow
Ring, can first obtain the noise of instrument background of wide spectrum light source and white light interference test device 3, then pass through the right of noise and signal
Than, determine the polarization crosstalk peak value of the generations to be measured such as waveguide chip, optical fiber Coupling point, specifically can be by changing device under test
2 to be realized with the alignment angle of wide spectrum light source and test device 3.
As shown in figure 4, when the transmission axle of inclined tail optical fiber 21,23 slow axis and waveguide chip 22 is protected in the input/output of waveguide device
(fast axle), to punctual, injected optical signal for 0 °～0 ° be aligned of input, is exported 0 °～0 ° to punctual, in θ1≈0、θ2The condition of ≈ 0
Under, the amplitude of white light interference signal of acquisition and optical path delay amount are approximately represented as：
In formula：θ1、θ2Alignment angle for input, output.
When the input/output inclined tail optical fiber 21 of guarantor of waveguide device, 23 fast axles are aligned with the transmission axle (fast axle) of waveguide chip 22
When, injection optical signal is 0 °～90 ° be aligneds of input, 90 °～0 ° of output to punctual, can be same to (10) identical result,
Only need to be changed into angle
Contrast (8) formula and (10) understand, when alignment angle θ1、θ2During change, in device under test, the interference peak of each point is (inclined
Shake cross-talk) light path position be not changed in, but interference signal (cross-talk amplitude) receives the modulation of soldering angle, works as θ1≈0、
θ2≈ 0 (or) when, polarization crosstalk peak value substantially will be greatly weakened；And measure and make an uproar
Sound, including：In wide spectrum light source spectrum ripple, white light interferometric device 3 other optical defects produce cross-talk peak value, due to
The angle of device under test injection light is unrelated, and its amplitude substantially can be constant.Therefore, by (9), (10) formula measurement result twice
Contrast, can be distinguish between to signal and noise.
For clearly demonstrating the optical property measuring method of integrated waveguide manipulator (Y waveguide) of the present invention, in conjunction with the embodiments
The invention will be further described with accompanying drawing, but should not be limited the scope of the invention with this.
The measurement of the Y waveguide device of fast axle of embodiment 1 tail optical fiber slow axis and waveguide chip
Device measurement apparatus are as shown in Fig. 2 the device selection of white light interferometric device is as follows with parameter：
(1) centre wavelength 1550nm of wide spectrum light source 11, half spectral width are more than 45nm, and fiber power is more than 2mW, light source light
Spectrum ripple<0.05dB (peak amplitude is about -60dB), the scope 4～7mm at relevant peak；Half spectral width of DFB light source 311 is little
In 50MHz, fiber power is more than 1mW；
(2) 2/98 fiber coupler 12 operation wavelength 1550nm, splitting ratio 2：98；
(3) fibre optic isolater 14 operation wavelength 1550nm, insertion loss 0.8dB；
(4) white light interferometer exports the polarizer 15, the operation wavelength of white light interferometer input analyzer 32 is 1550nm, disappears
For 30dB, insertion loss is less than 1dB to light ratio；
(5) the 1st, the insertion loss of the 2nd fiber rotation connector 17,30 is 1dB, and extinction ratio is better than 18dB；
(6) the 1st, operation wavelength 1310/1550nm of the 2nd fiber coupler 33,38, splitting ratio 50：50；
(7) fiber optical circulator 35 is three-port circulator, insertion loss 1dB, and return loss is more than 55dB；
(8) operation wavelength of GRIN Lens 36 is 1550nm, its 37 with mobile mirror (reflectance is more than 92%)
Between light path scanning distance change about between 0～200mm, average insertion loss be 2.0dB；
(9) the 1st, the 2nd, the light-sensitive material of the 3rd photodetector 13,391,392 be InGaAs, optical detection scope is
1100～1700nm, responsiveness is more than 0.85；
(10) operation wavelength 1550nm of Y waveguide device to be measured, waveguide tail optical fiber slow axis is aligned with the fast axle of waveguide chip, ripple
Lead chip length 20mm.
The idiographic flow of device measurement is as shown in Figure 1：
Understood according to step 501, measurement Y waveguide input tail optical fiber lW-iLength be：1.53 rice；
Understood according to step 502, input tail optical fiber lW-iTheoretical light path (Δ nfBy 5 × 10-4Meter) SW-i=0.765mm；And
Sripple=4～7mm is it is seen then that have to welding input extended fiber；
Understood according to step 503, connect extended fiber lf-iLength at least want 7 × 10-3/5×10-4=14 meters, actual
Choose 15 meters；
Understood according to step 504, the length of measurement waveguide chip is 20mm, its theoretical light path (Δ nWBy 8 × 10-2Meter) SW
=1.6mm, corresponding output tail optical fiber length lW-o=1.6 × 10-3/5×10-4=3.2 meters；
Understood according to step 505, measurement output tail optical fiber length lW-oFor 1.72 meters；
According to step 506～507, export the light path S of tail optical fiberW-o<SWIt is seen then that having to welding to input out prolongation
Fibre, welds extended fiber lf-oAt least want 3.2 meters, reality chooses 5.6 meters；
According to step 508,509, device under test is linked in white light interferometric device 3 as shown in Figure 2, due to being
First device is measured, and device tail optical fiber slow axis is aligned with waveguide chip fast axle, the adjustment countershaft angle of input/output is
0 ° -0 °, as shown in Figure 4；
According to step 511, start white light interferometric device, obtain measurement result as shown in figure 5,61 are expressed as measurement
Interfere main peak, it is measuring amplitude and light path position reference point；62 (62 '), 63 (63 ') are the spuious dry of measurement apparatus 3 light path
Relate to peak；The relevant peak of high-order that 64 (64 ') lead to for light source light spectrum ripple；65 (65 ') are the polarization crosstalk noise basis of measurement apparatus 3
Bottom, represents the measuring limit of measurement apparatus；
According to step 512, adjust input/output angle and be 0 ° -45 °, as shown in Figure 3；
According to step 513, it is again started up test device, obtain measurement result as shown in Figure 6；
According to step 514, contrast Fig. 5 and Fig. 6 test result twice, obtain characteristic peak 6A～6E (6A '～6E ' 6A respectively
～6E is symmetrical) totally 10 characteristic peaks；
By step 515～520, l is respectively according to input/output extended fiber lengthf-i=15.00 meters, lf-o=5.60
Rice, input/output tail optical fiber is respectively lW-i=1.53 meters, lW-o=1.72, waveguide chip length is 20mm, according to calculated
Light path ± (Sf-i+SW-i)、±(Sf-i)、±(Sf-o+SW-o)、±(Sf-o)、±(Sf-i+SW-i+SW-o+Sf-o-SW) it may be determined that special
Levy peak 6A～6E (6A '～6E ') to represent respectively, 6A, 6A ' for inputting pigtail coupling cross-talk；6B, 6B ' weld for input extended fiber
Point cross-talk；6C, 6C ' for exporting pigtail coupling cross-talk；6D, 6D ' for exporting extended fiber solder joint cross-talk；6E, 6E ' it is waveguide chip
Cross-talk；The each point polarization crosstalk amplitude that its measurement obtains and optical fiber refer to table 1 with the linear birefrigence of waveguide.
The measurement result of the Y waveguide device of fast axle of table 1 tail optical fiber slow axis and waveguide chip
The measured value amplitude of each point cross-talk is measurement error in ± 0.2dB as shown in Table 1, the wherein extinction ratio of waveguide chip
For 55.2 ± 0.2dB.
The measurement of the Y waveguide device of fast axle of embodiment 2 tail optical fiber fast axle and waveguide chip
Device measurement apparatus are also shown in FIG. 2, and, with embodiment 1, difference is to treat for the selection of measurement apparatus and parameter
The waveguide tail optical fiber fast axle surveying Y waveguide device is aligned with the fast axle of waveguide chip, waveguide chip length 30mm.
As shown in Figure 1, its test process is roughly the same with embodiment 1, and difference exists for the idiographic flow of device measurement
In：
(1) measurement Y waveguide input tail optical fiber length lW-i=6.11 meters, need also exist for connecting input extended fiber, take lf-i=
15.00 meters；
(2) measurement output tail optical fiber length lW-oFor 0.90 meter, the length of waveguide chip is 30mm；Need also exist for connecting and extend
Optical fiber, takes lf-o=5.60 meters；
(3) according to step 508,510, device tail optical fiber fast axle is aligned with waveguide chip fast axle, adjustment input/output to shaft angle
Spend for 0 ° -90 °, 90 ° -0 °, start white light interferometric device, obtain first time measurement data, i.e. Noise Background result such as Fig. 7
Shown；In figure 71 is expressed as the interference main peak measuring, and it is measuring amplitude and light path position reference point；72(72’)、73(73’)、
74 (74 ') are the spuious interference peaks of measurement apparatus 3 light path；The relevant peak of high-order that 75 (75 ') lead to for light source light spectrum ripple；76
(76 ') for the polarization crosstalk Noise Background of measurement apparatus 3, represent measuring limit；
(4) according to step 512, adjustment alignment angle is 45 ° -0 °, 0 ° -45 °, obtains second test result such as accompanying drawing 8；
(5) according to step 514～520, contrast Fig. 7 and Fig. 8 test result twice, according to lf-i=15.00 meters, lf-o=
5.60 meters, lW-i=6.11 meters, lW-o=0.90 meter, lW=30mm, determines ± (S in Fig. 8f-i+SW-i)、±(Sf-i)、±(Sf-o+
SW-o)、±(Sf-o)、±(Sf-i+SW-i+SW-o+Sf-o+SW) it may be determined that each point implication of characteristic peak 7A～7E (7A '～7E '),
Cross-talk amplitude, linear birefrigence etc. refer to table 2.
The measured value amplitude of each point cross-talk (measurement error) within ± 0.2dB as shown in Table 2, the extinction ratio of waveguide chip
For 47.7 ± 0.2dB.
The measurement result of the Y waveguide device of fast axle of table 2 tail optical fiber fast axle and waveguide chip
Claims (1)
1. a kind of optical property measuring method of multi-functional Lithium metaniobate integrated device it is characterised in that：
(1) length l of inclined tail optical fiber is protected in the input of measurement waveguide deviceW-i, detection transmission light wave between the input inclined tail optical fiber fast and slow axis of guarantor
Optical path difference SW-iThe light path S at the relevant peak whether producing more than light source light spectrum rippleripple, that is,
SW-i>Sripple,
SW-i=lW-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber；
(2) if length l of inclined tail optical fiber is protected in inputW-iIt is unsatisfactory for the condition in step (1), then protect in input and weld on inclined tail optical fiber
One section of input extends polarization maintaining optical fibre, and the countershaft angle of solder joint is 0 ° -0 °, and length is lf-iInput extend polarization maintaining optical fibre meet light
Path difference Sf-iThe light path S at the relevant peak producing more than light source light spectrum rippleripple, that is,
Sf-i>Sripple
Sf-i=lf-i×Δnf, Δ nfProtect the linear birefrigence of inclined tail optical fiber, measure and record the length that input extends polarization maintaining optical fibre
lf-i；
(3) measure length l of waveguide chipW；
(4) length l of inclined tail optical fiber is protected in the output of measurement waveguide deviceW-o, detection transmission light wave between the output inclined tail optical fiber fast and slow axis of guarantor
Optical path difference SW-oWhether more than optical path difference S transmitting light wave between waveguide chip fast and slow axisW, that is,
SW-o>SW, SW-o=lW-o×Δnf, SW=lW×ΔnW, Δ nWThe linear birefrigence of waveguide chip；
(5) if length l of inclined tail optical fiber is protected in outputW-oIt is unsatisfactory for the condition of step (4), then protect in output and on inclined tail optical fiber, weld one
Section output extends polarization maintaining optical fibre, and the countershaft angle of solder joint is 0 ° -0 °, and length is lf-oOutput extend polarization maintaining optical fibre optical path difference
Sf-o
Sf-o>SW, Sf-o=lf-o×Δnf, measure and record length l that output extends polarization maintaining optical fibref-o；
(6) slow axis of inclined tail optical fiber and the transmission axle of waveguide chip are protected in be aligned input or output, when no input extends polarization maintaining optical fibre, defeated
Enter to protect the countershaft angle, θ that inclined tail optical fiber exports the tail optical fiber of the polarizer with white light interferometer1For 0 ° -0 °；Input is had to extend polarization maintaining optical fibre
When, input extends the countershaft angle, θ that polarization maintaining optical fibre exports the tail optical fiber of the polarizer with white light interferometer1Also it is 0 ° -0 °；No output is prolonged
During long polarization maintaining optical fibre, the countershaft angle, θ that inclined tail optical fiber inputs the tail optical fiber of analyzer with white light interferometer is protected in output2For 0 ° -0 °；Have defeated
When going out to extend polarization maintaining optical fibre, output extends the countershaft angle, θ that polarization maintaining optical fibre inputs the tail optical fiber of analyzer with white light interferometer2Also it is
0°-0°；
Be aligned input or the transmission axle exporting the inclined tail optical fiber fast axle of guarantor and waveguide chip, input is protected inclined tail optical fiber or is inputted prolongation guarantor partially
Optical fiber exports the countershaft angle, θ of the tail optical fiber of analyzer with white light interferometer1For 0 ° -90 °；Inclined tail optical fiber is protected in output or output extends
Polarization maintaining optical fibre inputs the countershaft angle, θ of the tail optical fiber of analyzer with white light interferometer2For 90 ° -0 °；
(7) first time distributed polarization crosstalk measurement result, i.e. instrument polarization this truth of a matter of cross-talk noise of white light interferometer are obtained
According to its abscissa is scanning light path numerical value S, unit：μm, vertical coordinate is polarization crosstalk amplitude E, unit：dB；The light path of measurement is swept
Retouch range delta S
ΔS>2(Sf-i+SW-i+SW+SW-o+Sf-o)
And, the midpoint of light path sweep limitss is the position of the peak-peak of polarization crosstalk measurement data；
(8) convert the light injection condition of waveguide device：When no input extends polarization maintaining optical fibre, inclined tail optical fiber and white light interferometer are protected in input
The countershaft angle, θ of the tail optical fiber of the input polarizer1For 0 ° -45 °；When having input to extend polarization maintaining optical fibre, input extend protect polarisation with white
Optical interferometer inputs the countershaft angle, θ of the tail optical fiber of the polarizer1Also it is 0 ° -45 °；When no output extends polarization maintaining optical fibre, output is protected partially
Tail optical fiber exports the countershaft angle, θ of the tail optical fiber of analyzer with white light interferometer2For 45 ° -0 °；When having output to extend polarization maintaining optical fibre, defeated
Go out to extend the countershaft angle, θ of polarization maintaining optical fibre and tail optical fiber2Also it is 45 ° -0 °；
(9) second distributed polarization crosstalk measurement result, i.e. the optical polarization crosstalk measurement data of device are obtained, its light path is swept
The requirement retouching range delta S is identical with step (7)；
(10) by the analysis of data and calculating, obtaining chip delustring, the linear birefrigence of chip of waveguide device, waveguide is defeated
Enter/coupling the cross-talk of outfan tail optical fiber, the linear birefrigence optical parameter of tail optical fiber：
(10.1) white light being obtained the device distributed polarization crosstalk measurement result that measuring process (9) obtains with step (7) is done
The instrument polarization cross-talk background data of interferometer is contrasted, it is possible to obtain some inclined by waveguide chip, waveguide input or output guarantor
Tail optical fiber, input or output extend the polarization crosstalk characteristic peak that polarization maintaining optical fibre introduces, and the abscissa of peak value corresponds to optical path difference S, unit：
μm, amplitude E of the corresponding polarization crosstalk of vertical coordinate, unit：dB；
(10.2) extend length l of polarization maintaining optical fibre according to inputf-iNumerical value, is calculated the theoretical light that input extends polarization maintaining optical fibre
Cheng Yanchi numerical value SF-i (theoretical), SF-i (theoretical)=lf-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter；Device polarization crosstalk test data
In, determination meets optical path delay amount S by what the solder joint of input prolongation polarization maintaining optical fibre and the input inclined tail optical fiber of guarantor causedF-i (theoretical)Polarization
Cross-talk peak value, its Y value corresponds to solder joint cross-talk value Ef-i, abscissa correspond to input extend the real light path of polarization maintaining optical fibre
Retardation SF-i (measures)；
(10.3) length l protecting inclined tail optical fiber is inputted according to waveguideW-iNumerical value, is calculated the theoretical light that inclined tail optical fiber is protected in waveguide input
Cheng Yanchi numerical value SW-i (theoretical), SW-i (theoretical)=lW-i×ΔnF (theoretical), Δ nF (theoretical)By 5 × 10-4Meter；In device test data, determine
Meet optical path delay amount S by what the input inclined tail optical fiber sound of guarantor causedF-i (measures)+SW-i (theoretical)Polarization crosstalk peak value, its vertical coordinate couple
Cross-talk value EW-i, abscissa real optical path delay amount S of correspondenceF-i (measures)+SW-i (measures)；
(10.4) length l of polarization maintaining optical fibre is inputted according to waveguideW-iWith its corresponding true optical path delay amount SW-i (measures), Ke Yijing
Really it is calculated the linear birefrigence Δ n that waveguide inputs polarization maintaining optical fibreF-i (measures),
ΔnF-i (measures)=SW-i (measures)/lW-i
(10.5) with step 2)～step 4) identical, extend length l of polarization maintaining optical fibre according to outputf-o, waveguide output protect inclined tail optical fiber
Length lW-o, determine that output extends polarization maintaining optical fibre and solder joint cross-talk value E of inclined tail optical fiber is protected in outputf-o, output optical fibre and waveguide chip
Power coupling cross-talk value EW-o, and the linear birefrigence Δ n of waveguide output polarization maintaining optical fibreW-o；
ΔnW-o (measures)=SW-o (measures)/lW-o
(10.6) length l according to waveguide chipW, it is calculated that waveguide chip is fast, optical path delay amount S between slow axisW (theoretical),
SW (theoretical)=lW×ΔnW (theoretical), linear birefrigence Δ nW (theoretical)By 8 × 10-2Meter；In device polarization crosstalk test data, permissible
Input the inclined tail optical fiber of guarantor, input prolongation polarization maintaining optical fibre, the output inclined tail optical fiber of guarantor, output prolongation polarization maintaining optical fibre and waveguide chip soon, slowly
Light path sum S is produced between working shaftF-i (measures)+SW-i (measures)+SW (theoretical)+SW-o (measures)+SF-o (measures)Or difference S of light pathF-i (measures)+
SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (theoretical)At corresponding abscissa, find the polarization crosstalk peak value of waveguide chip, its amplitude
EWAbsolute value be waveguide chip extinction ratio；Waveguide chip cross-talk peak value occurs in light path sum SF-i (measures)+SW-i (measures)+
SW (measures)+SW-o (measures)+SF-o (measures)Place is it may be determined that the fast axle of waveguide tail optical fiber is aligned with waveguide fast axle, and occurs in the difference of light path
SF-i (measures)+SW-i (measures)+SW-o (measures)+SF-o (measures)-SW (theoretical)Then determine that the slow axis of waveguide tail optical fiber is aligned with waveguide fast axle；According to measurement
Optical path delay amount S of the waveguide chip obtainingW (measures)Actual length l with waveguide chipW, it is calculated the linear of waveguide chip
Birefringence nW (measures)
ΔnW (measures)=SW (measures)/lW.
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| CN104280215B (en) * | 2014-10-11 | 2017-02-15 | 哈尔滨工程大学 | Dual-channel optical performance bi-directional multi-alignment-angle automatic testing device for Y waveguide |
| CN104280216B (en) * | 2014-10-11 | 2017-05-24 | 哈尔滨工程大学 | Dual-channel optical performance simultaneous testing device for Y waveguide device and Y waveguide polarization crosstalk recognizing and processing method thereof |
| CN106989904B (en) * | 2017-04-25 | 2020-01-17 | 哈尔滨工程大学 | Method for measuring extinction ratio of polarization maintaining optical fiber |
| CN107314888B (en) * | 2017-04-25 | 2019-08-06 | 哈尔滨工程大学 | The polarization property measurement method of multi-functional lithium niobate integrated device |
| CN108106817B (en) * | 2017-12-11 | 2019-12-24 | 哈尔滨工程大学 | Method for improving polarization performance measurement accuracy of Y waveguide device |
| CN110492941B (en) | 2018-05-14 | 2021-01-29 | 华为技术有限公司 | Optical signal receiving and transmitting device |
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