Embodiment
Below in conjunction with drawings and Examples, the present invention is described in detail.
The present invention proposes a kind of reflective reciprocity optical voltage transformer based on Pockels effect and method for designing thereof, the optical voltage transformer light path obtained by described method for designing, the additional birefringence error that electro-optic crystal is introduced because of self-defect and the factor such as environment temperature, STRESS VARIATION can not only be eliminated, and make whole optical voltage transformer light path have immunocompetence to surrounding environment interference, the linear electrooptic phase retardation simultaneously introduced by voltage to be measured doubles, thus improves the measuring precision, stability, antijamming capability and adaptive capacity to environment.Described light path design method is:
As Fig. 5, polarized light generation module 1 produces the orhtogonal linear polarizaiton light E of two homenergics
xand E
y, in forward-propagating process, pairwise orthogonal linearly polarized light enters into optically-active module 3 through protecting off-delay optical cable 2, wherein, and E
xalong protecting the fast shaft vibration of off-delay optical cable 2, E
yvibrate along slow axis.Pairwise orthogonal linearly polarized light enters sensing module 4 through optically-active module 3, sensing module 4 is made up of identical electro-optic crystal A401 and electro-optic crystal B402 and half-wave plate 403, it is middle and at 45 ° to axle perpendicular to the principal-axes coordinate of inducting of polarized light direction of propagation plane with two electro-optic crystals that half-wave plate 403 is positioned at two electro-optic crystals, reach the effect making pairwise orthogonal linearly polarized light modes swap, namely in electro-optic crystal A401 along X(Y) linearly polarized light of shaft vibration in electro-optic crystal B402 along Y(X) direction of principal axis vibration, thus realize light path reciprocity in sensing module 4, eliminate additional birefringence error in electro-optic crystal B402, improve optical voltage transformer the measuring precision and adaptive capacity to environment.Electro-optic crystal B402 is in the uniform electric field of voltage to be measured generation, thus linearly polarized light can be made to produce the linear electrooptic phase retardation carrying information of voltage to be measured, and because reflective structure and electro-optic crystal A401 be not by the design of electric field influence, the linear electrooptic phase retardation of final acquisition doubles, and improves the measuring precision.Pairwise orthogonal linearly polarized light again enters optically-active module 3 by sensing module 4 after sensing module 4 end is reflected, and optically-active module 3, by the effect of the twice pair of pairwise orthogonal linearly polarized light in front and back, makes polarized light backpropagation in time protecting in off-delay optical cable 2, E
xalong slow-axis direction vibration, E
yalong quick shaft direction vibration, thus form the modes swap of pairwise orthogonal linearly polarized light in guarantor's off-delay optical cable 2, improve environment resistant interference performance.Pairwise orthogonal linearly polarized light returns polarized light generation module 1, then interferes and accept certain process to obtain information of voltage to be measured.
Based on above-mentioned light path design method, the invention provides a kind of reflective reciprocity optical voltage transformer based on Pockels effect, its light channel structure as shown in Figure 5, comprises the polarized light generation module 1, guarantor's off-delay optical cable 2, optically-active module 3 and the sensing module 4 that connect in turn.Wherein, polarized light generation module 1 is by the light source 101(superluminescent diode SLD connected in turn, the wavelength of optical signal provided is 1310nm), circulator 102(single-mode optical circulator), the polarizer 103(optical fiber polarizer, it act as and input nonpolarized light is converted to required linearly polarized light), phase-modulator 104(integrated optic phase modulator, with lithium niobate linear electro-optic effect for principle is made, complete the phase-modulation to input light) and connect circulator 102 and the photodetector 105(PIN-FET detector on another branch road of phase-modulator 104) and digital information processing system 106.Be connected by protecting off-delay optical cable 2 between polarized light generation module 1 with optically-active module 3, optically-active module 3 is that the faraday that Faraday polarization apparatus and collimator of PMF encapsulate collimates polarization apparatus, and Faraday polarization apparatus is by sensing module 4 input side.Sensing module 4 is made up of two identical electro-optic crystal A401 and electro-optic crystal B402 and the half-wave plate 403 be positioned between the two, and described electro-optic crystal B402 end is the catoptron 404 of high reflectance, and electro-optic crystal B402 upper and lower side adds voltage U to be measured.
Described circulator 102 is three port single-mode fiber circulators, its effect is that the light signal low-loss making SLD send is coupled into light path system, wherein, first port is connected with light source 101 as input end in polarized light forward-propagating process, second port is connected with the polarizer 103 as input end in output terminal in polarized light forward-propagating process and back-propagation process, and the 3rd port connects photodetector 105 as output terminal in polarized light back-propagation process.The effect of described photodetector 105 is that the interference light intensity signal carrying information of voltage to be measured is converted to electric signal, this electric signal is received by digital information processing system 106, and wherein demodulated, export simultaneously formed feedback signal pass to phase-modulator 104.
The polarizer 103 tail optical fiber and phase-modulator 104 enter fibre with 45 ° to axle welding, effect is that order enters phase-modulator 104 by 45 ° to the pairwise orthogonal linearly polarized light that the linearly polarized light of axle fusion point is decomposed into homenergic, and direction of vibration is respectively along the fast axle of phase-modulator 104 and slow axis.The driving voltage that described phase-modulator 104 pairs of light signals carry out phase-modulation comes from digital information processing system 106, the phase modulation that phase-modulator 104 produces the positive and negative light signal passed twice through is different, and phase modulation acts on different linearly polarized lights, thus the modulation result of final phase-modulator 104 pairs of light signals is the phase modulation difference of twice generation in front and back, this difference comprises two phase masses, and one is inherent delay phase
effect is the light intensity signal making finally to be detected by photodetector 105 is sine function, two are and linear electrooptic phase retardation equal and opposite in direction, phase mass that symbol is contrary, effect makes the phase value of sine function in final light intensity signal remain on zero crossings, and the two acting in conjunction improves the linear of optical voltage transformer output signal.
Protect off-delay optical cable 2 and have more than 200m, play time delay effect as while lightray propagation medium, be connected between phase-modulator 104 and optically-active module 3.Faraday polarization apparatus in described optically-active module 3 is made up of magneto-optical crystal yttrium iron garnet (YIG) and permanent magnet magnetic ring, and effect is the rotation polarized light entered wherein being carried out to plane of polarization along certain direction.Make the saturation flux value of a little higher than yig crystal of the magnetic flux value of permanent magnet magnetic ring, design yig crystal length simultaneously, the plane of polarization anglec of rotation making it produce under saturation flux amount is 45 °, and the minor fluctuations of magnetic flux can not impact the anglec of rotation of plane of polarization, improve Faraday polarization apparatus anti-electromagnetic interference capability.
In optically-active module 3 faraday collimate guarantor's inclined tail optical fiber fast and slow axis of polarization apparatus and electro-optic crystal A401, electro-optic crystal B402 principal-axes coordinate of inducting at 45 ° to axle, namely be 45 ° with X, Y direction angle in Fig. 5, object is that the pairwise orthogonal linearly polarized light making the plane of polarization collimating polarization apparatus outgoing by faraday rotate 45 ° enters electro-optic crystal A401 after vibration direction respectively along induct principal-axes coordinate X-axis and the Y direction of electro-optic crystal A401.Electro-optic crystal A401 is consistent with the principal-axes coordinate direction of inducting of electro-optic crystal B402, the principal-axes coordinate X that inducts, the Y-axis of the fast and slow axis of half-wave plate 403 and electro-optic crystal A401 and electro-optic crystal B402 are at 45 ° to axle, effect is exchanged by the pairwise orthogonal linearly polarized light polarization mode by half-wave plate 403, thus make same linearly polarized light direction of vibration in electro-optic crystal A401 and electro-optic crystal B402 orthogonal.
Described electro-optic crystal A401 and the incidence of electro-optic crystal B402 light all apply anti-reflection film with light exit side face, and the effect of this anti-reflection film is that the light low-loss making wavelength coverage near 1310nm is passed through.As shown in Figure 7, electro-optic crystal B402 end adds high reflectivity mirror 404, and reflectivity is more than 99.5%.On electro-optic crystal A401 and electro-optic crystal B402, downside is equipped with identical metal electrode, but in virtual voltage measuring process, electro-optic crystal A401 is as compensated crystal, for eliminating in electro-optic crystal B402 because of self-defect and environment temperature, the additional birefringence error that the factors such as STRESS VARIATION are introduced, therefore do not power up, and electro-optic crystal A401 should try one's best not by electric field influence, electro-optic crystal B402 is as sensing crystal, for sensitivity voltage signal to be measured, upper/lower electrode adds voltage U to be measured, thus, electro-optic crystal B402 works in uniform electric field environment, two electro-optic crystals other working environments residing are identical.
Be modeled as instrument with Jones matrix below and prove the reciprocity of the reflective reciprocity optical voltage transformer light channel structure based on Pockels effect provided by the invention and the eliminating effect to birefringence error additional in electro-optic crystal thereof by reference to the accompanying drawings, specific as follows:
1) light that sends of light source is through circulator 102, enters the polarizer 103, supposes that the printing opacity direction of the polarizer 103 is parallel with Y-axis, and the direction of vibration of the linearly polarized light obtained is as shown in bold arrow in Fig. 2 (A).The vertical paper in the direction of propagation of light is outside.
The Jones matrix of the polarizer 103 is expressed as:
Subscript " 1 " represents forward-propagating process.
2) linearly polarized light arrives 45 ° of fusion points of the polarizer 103 and phase-modulator 104, and this fusion point realizes the rotation to coordinate axis.Polarized light along former coordinate axis Y vibration is broken down into X, Y-axis component under new coordinate axis, obtains the pairwise orthogonal linearly polarized light E of homenergic
xand E
y.Suppose left-handed 45 ° of coordinate axis herein, thus obtain Fig. 2 (B), wherein E
xbe parallel to X-axis, E
ybe parallel to Y-axis, thus define E
xfor the X component in Jones matrix expression formula, E
yfor Y-component.
The Jones matrix expression formula of 45 ° of fusion points is:
3) pairwise orthogonal linearly polarized light enters phase-modulator 104 through 45 ° of fusion points, and phase-modulator 104 pairs of pairwise orthogonal linearly polarized lights are modulated, and produces phase place
suppose that X-direction is quick shaft direction, now direction of vibration E
xbe parallel to X-axis, thus the Jones matrix expression formula obtaining phase-modulator 104 is:
4) enter faraday by the light of phase-modulator 104 outgoing and collimate polarization apparatus, in this rotation through collimator and extender and plane of polarization.Faraday polarization apparatus take Faraday effect as theoretical foundation, to the optical device that the plane of polarization of polarized light rotates, but not to coordinate axis effect.Suppose Faraday polarization apparatus to polarized light left-handed 45 °, thus obtain Fig. 2 (C).
The Jones matrix that faraday collimates polarization apparatus is:
5) direction of vibration of the coordinate axis shown in Fig. 2 (C) and linearly polarized light has the angle of 45 °, parallel with the principal-axes coordinate of inducting in the electro-optic crystal A401 polarized light plane of incidence for making linearly polarized light collimate polarization apparatus outgoing after vibration direction from faraday, faraday need be made to collimate between polarization apparatus and electro-optic crystal A401 45 ° to axle.45 ° is the rotation to coordinate axis to axle equally, supposes left-handed 45 ° of coordinate axis herein, obtains result shown in Fig. 2 (D).
45 ° to axle place Jones matrix expression formula are:
6) suppose that the X-axis of electro-optic crystal A401 is quick shaft direction, now E
xbe parallel to X-axis, but due in electro-optic crystal A401 place electric field, without the linear electro-optic effect that voltage to be measured is introduced, so linear electrooptic Delay phaseδ=0, therefore only containing the additional birefringent retardation phase delta introduced because of electro-optic crystal A401 self-defect and the factor such as environment temperature, STRESS VARIATION.
The Jones matrix expression formula of electro-optic crystal A401 is:
7) electro-optic crystal B402 is entered from the pairwise orthogonal linearly polarized light of electro-optic crystal A401 end outgoing through half-wave plate 403, the effect of half-wave plate 403 is by principal-axes coordinate angle at 45 ° of inducting in its fast axle and the electro-optic crystal B402 polarized light plane of incidence, the vibration mode of pairwise orthogonal linearly polarized light is exchanged.As Fig. 2 (D) arrives shown in the change procedure of (E).
Thus, the Jones matrix expression formula of this half-wave plate 403 is:
When it should be noted that the fast axle of half-wave plate 403 and X-axis angle are-45 °, the Jones matrix expression formula obtained is identical with formula (7).
8) when pairwise orthogonal linearly polarized light enters electro-optic crystal B402, direction of vibration is as shown in Fig. 2 (E), now, X-axis is still quick shaft direction, a Delay phaseδ+Δ will be produced between pairwise orthogonal linearly polarized light, wherein δ is the linear electrooptic phase retardation introduced by voltage to be measured, and Δ is phase retardation that in electro-optic crystal B402, additional birefringence is introduced and equal with the additional birefringent retardation phase place in electro-optic crystal A401 in theory, just acts on different polarized components.
The Jones matrix expression formula of electro-optic crystal B402 is:
9) reflected by catoptron 404 after polarized light propagates into the end of electro-optic crystal B402, the direction of vibration of catoptron 404 pairs of coordinate axis and polarized light all has reflection and turning effort.As Fig. 2 (E) arrives shown in the change procedure of (F).
For the effect of coordinate axis, when normal reflection, light is propagated along Z axis, and the coordinate axis Z axis after reflection is reverse, and supposes that the plane of incidence is YZ plane, because X-axis is perpendicular to the plane of incidence, reflect rear to constant, according to the right-hand rule, under coordinate axis newly can be obtained, Y is reverse, can obtain as shown in Figure 3 the X-axis rotate process of (E) to (F ').
For linearly polarized light, because pairwise orthogonal linearly polarized light E
x, E
yall reverse under catoptron 404 acts on, phase place change is π, as shown in Figure 4, so pairwise orthogonal linearly polarized light phase difference variable turns to 0 in Jones matrix expression formula, now only need consider the reflex of catoptron 404 pairs of coordinate axis.
The Jones matrix expression formula of catoptron 404 is:
Since then, linearly polarized light back-propagation process is entered.
10) the pairwise orthogonal linearly polarized light after reflection, again through electro-optic crystal B402, in being contrasted, is still now E from Fig. 2 (E), Fig. 2 (F)
yparalleled by X axis, E
xbe parallel to Y-axis, identical when action effect and forward-propagating.
Therefore, the Jones matrix expression formula of electro-optic crystal B402 is:
Subscript " 2 " represents back-propagation process.
11) in back-propagation process, although coordinate axis Y-axis is reversed by catoptron 404, but principal-axes coordinate angle of inducting in the fast axle of half-wave plate 403 and the electro-optic crystal A401 polarized light plane of incidence is still 45 °, same effect pairwise orthogonal linearly polarized light being played to modes swap, therefore can obtain Fig. 2 (G) from Fig. 2 (F).
Now the Jones matrix expression formula of half-wave plate 403 is:
12) pairwise orthogonal linearly polarized light enters electro-optic crystal A401 again, and direction of vibration is as shown in Fig. 2 (G).Comparison diagram 2(D) and Fig. 2 (G) known, with forward by time identical, be still E in electro-optic crystal A401
xalong fast axle X-direction vibration, E
yalong Y direction vibration, identical when therefore Jones matrix passes through with forward, that is:
13) 45 ° is rotation to coordinate axis to axle, therefore, during polarized light forward-propagating, left-handed to coordinate axis is observed in the direction of propagation in face of light, when backpropagation, still observes in face of light, be similarly left-handed, because the vertical paper of Z axis during backpropagation is inside, being coordinate axis dextrorotation in fig. 2 so left-handed axle is reflected to, is namely by the change of Fig. 2 (G) to Fig. 2 (H).
Now, 45 ° to the Jones matrix expression formula of axle are:
14) backpropagation of pairwise orthogonal linearly polarized light collimates polarization apparatus to faraday, its nonreciprocity makes polarized light plane of polarization again rotate 45 ° along the direction identical with during forward-propagating, to be reflected on Fig. 2 namely again left-handed 45 °, to obtain Fig. 2 (I) by Fig. 2 (H).But reality is observed in face of light, become dextrorotation 45 °, thus it is different from during forward-propagating to obtain Jones matrix expression formula, that is:
15) the pairwise orthogonal linearly polarized light collimating polarization apparatus outgoing by faraday enters phase-modulator again, the effect of phase-modulator is constant, suppose that front and back are passed through for twice to be lasted for, this time, then now the Jones matrix expression formula of phase-modulator was primarily of the cut to lengthen protecting off-delay optical cable:
16) backpropagation arrives 45 ° of fusion points, obtain Fig. 2 (J), and Jones matrix is constant, and now the Jones matrix expression formula of 45 ° of fusion points is:
17) the orhtogonal linear polarizaiton light carrying information of voltage to be measured arrives the polarizer 103 place with the coordinate shown in Fig. 2 (J) and direction of vibration, pairwise orthogonal linearly polarized light is interfered respectively on X and Y-axis, only has interference light along the polarizer 103 printing opacity direction just by the polarizer 103, be converted to electric signal through circulator 102 by photodetector 105 and send into digital information processing system 106 and process, obtain sending into the feedback signal of phase-modulator 104 and carrying the digital output signal of information of voltage to be measured.
The Jones matrix of the polarizer 103 is identical with during forward-propagating, is:
So far, the output interference light intensity expression formula of the whole reflective reciprocity optical voltage transformer light path system based on Pockels effect can be obtained.
By
After arrangement:
By formula I=E
out *e
out, and | E
y|
2=I
ican obtain,
Wherein, I
ifor input light intensity, δ is the linear electrooptic phase retardation that voltage to be measured is introduced,
with
for positive and negative twice through phase-modulator 104 produce phase retardation, wherein contain inherent delay phase place
and sent to the phasing degree of phase-modulator 104 as value of feedback by closed-loop digital signal processing system
.Therefore can obtain final output intensity expression formula is:
In theory,
time, the closed-loop digital signal processing system that native system adopts reaches stable closed loop and exports, and system works is in linear zone.
The computation process of the described linear electrooptic Delay phaseδ value introduced by voltage to be measured is as follows:
The dot product kr of wave vector k and position coordinates vector r reflects the phase retardation size of electromagnetic wave in spatial process, and therefore, the electro-optic delay phase place δ produced by linear electro-optic effect also can be expressed as:
δ=k·r (22)
In the present system, position coordinates vector r is light along the propagation distance L in Z-direction, and wave vector k is (angle) wave number of the monochromatic wave of light when propagating in BGO crystal, therefore carries birefringence information, that is:
Wherein, λ is light wavelength in a vacuum, b
zfor the birefraction of light propagated along Z axis.If refractive index is n when BGO crystal does not power up
0, because coordinate axis X is parallel to direction of an electric field, and hypothesis electric field intensity is E, so X-axis is inducted, refractive index is n
x=n
0, Y-axis perpendicular to
face, so Y-axis is inducted, refractive index is
or
, therefore b
z=| n
x-n
y|, namely
Therefore can obtain, direction of an electric field is parallel to X-direction, and in the transverse modulation situation that light is propagated along Z-direction, the electro-optic delay phase place of generation is:
Wherein, L is electro-optic crystal optical direction length, and d is the interelectrode distance producing voltage to be measured, and U is added magnitude of voltage to be measured on BGO crystal.
In sum, along the direction of propagation of light, comparison diagram 2(B) and Fig. 2 (I), this reflective reciprocity optical voltage transformer based on Pockels effect achieves the linearly polarized light modes swap being collimated polarization apparatus by the polarizer 103 to faraday, along X(Y in i.e. forward-propagating process) become along Y(X in the linearly polarized light back-propagation process of shaft vibration) shaft vibration, equally, comparison diagram 2(D) and Fig. 2 (E) and Fig. 2 (G) and Fig. 2 (F) known, present invention achieves linearly polarized light modes swap in two electro-optic crystals, i.e. E in electro-optic crystal A401
xbe parallel to X-axis, E
ybe parallel to Y-axis, and E in electro-optic crystal B402
xbe parallel to Y-axis, E
ybe parallel to X-axis.Twice linearly polarized light modes swap has achieved the reciprocity of whole light channel structure.From derivation and the final light intensity signal Output rusults of whole light path system Jones matrix, finally convert to not containing the phase retardation Δ adding birefringence introducing in electro-optic crystal B402 in the light signal of electric signal, demonstrate the correctness of reciprocity light path from numerical evaluation angle and add the theoretic validity of birefringence error inhibiting effect to electro-optic crystal B402.The coefficient of final interference light intensity signal neutral line electro-optic delay phase place is 2, proves to retain while reciprocity light path eliminates additional birefringence error and has doubled the linear electrooptic phase retardation introduced by voltage to be measured.More than be the correctness jointly proving the reflective reciprocity of the optical voltage transformer based on the Pockels effect light path design method that the present invention proposes from theoretical analysis and numerical evaluation two aspect.
As shown in Figure 6, BGO(Bi is with electro-optic crystal A401 and electro-optic crystal B402
4ge
3o
12) crystal is example, and the cutting mode of electro-optic crystal A and electro-optic crystal B is described.BGO crystal carries out orientation, cutting along three the principal-axes coordinate directions of inducting produced after perpendicular to added electric field on (001) direction, face, form the rectangular parallelepiped of formed objects, thus BGO crystal six faces obtained is respectively: (001),
(110),
two BGO crystal principal-axes coordinate direction of inducting is: X-axis perpendicular to (001) face, Y-axis perpendicular to
face, Z axis is perpendicular to (110) face, thus the electro-optic crystal A401 obtained in the present invention and electro-optic crystal B402.Electro-optic crystal A401 and electro-optic crystal B402 optical direction along inducting principal-axes coordinate Z-direction, therefore two electro-optic crystals (110) face and
all need to apply anti-reflection film, on electro-optic crystal B402, applied field direction is perpendicular to (001) face, is namely parallel to X-axis.BGO crystal all can facilitate system in package, debugging along the cutting of the direction of principal-axes coordinate of inducting, and linear electrooptic Late phase place value optical voltage transformer system of the present invention being obtained according to above-mentioned cutting and logical light step mode is maximum.
Carry out describing to the reflective reciprocity optical voltage transformer course of work based on Pockels effect provided by the invention by composition graphs 2 below.
Figure 2 shows that the process of system coordinates conversion and the change of polarized light direction of vibration in whole reflective reciprocity optical voltage transformer light path system.Light is propagated along Z axis, draws for convenience and is described, and in Fig. 2, in polarized light forward-propagating process, Z axis is outside perpendicular to paper, and in back-propagation process, the vertical paper of Z axis is inside.The reflective reciprocity optical voltage transformer light channel structure course of work based on Pockels effect provided by the present invention is: the light that superluminescent diode (SLD) 101 sends enters the optical fiber polarizer 103 through single-mode optical circulator 102, the optical direction of the polarizer 103, along horizontal or vertical direction, is assumed to be vertical direction herein.The linearly polarized light that the polarizer 103 exports is broken down into the equal pairwise orthogonal linearly polarized light of energy through 45 ° of fusion points, (Ex, Ey in Fig. 2 represent now pairwise orthogonal linearly polarized light respectively), pairwise orthogonal linearly polarized light enters phase-modulator 104 respectively along its fast and slow axis direction vibration (A-B as in Fig. 2) simultaneously.After obtaining phase-modulation, pairwise orthogonal linearly polarized light enters faraday through guarantor's off-delay optical cable 2 and collimates polarization apparatus, after collimator and extender and 45 ° of optically-actives, enters electro-optic crystal A401(as the B-C in Fig. 2).Due to faraday, to collimate induct principal-axes coordinate X, Y-axis of polarization apparatus and electro-optic crystal A401 at 45 ° to axle, therefore, and the X of pairwise orthogonal linearly polarized light respectively along principal-axes coordinate of inducting after entering electro-optic crystal A401, Y direction vibration (C-D as in Fig. 2).Pairwise orthogonal linearly polarized light enters half-wave plate 403 after electro-optic crystal A401, due to fast, the slow axis of half-wave plate 403 and the principal-axes coordinate X that inducts, the Y-axis angle at 45 ° of electro-optic crystal A401 and electro-optic crystal B402, thus orhtogonal linear polarizaiton light emergence pattern before entering electro-optic crystal B402 is exchanged, namely along Y (X) direction of principal axis vibration (as D-E in Fig. 2) after entering electro-optic crystal B402 along the linearly polarized light of electro-optic crystal A401X (Y) shaft vibration, thus make two electro-optic crystals contrary to the action effect of line polarisation, form compensation effect.Pairwise orthogonal linearly polarized light is reflected by catoptron 404 at the end of electro-optic crystal B402, as the E-F in Fig. 2, returns by original optical path, thus enters back-propagation process by polarized light forward-propagating process.Reflected light is through half-wave plate 403, same generation cross line polarisation modes swap, as the F-G in Fig. 2, and again collimate polarization apparatus through faraday, due to its nonreciprocity, polarized light is made now again to rotate 45 ° along sense of rotation during forward-propagating, as the H-I in Fig. 2, thus after the positive and negative faraday of passing twice through collimates polarization apparatus, there are 90 ° of rotations in pairwise orthogonal linearly polarized light, rock mechanism exchanges, namely vibrate along in the line polarisation reverse transfer process of guarantor's off-delay optical cable X (Y) shaft vibration along Y (X) direction of principal axis during forward transmission, as B and the I contrast in Fig. 2.So far, through twice modes swap, define reflective reciprocity light channel structure completely.When pairwise orthogonal linearly polarized light arrives the polarizer 103 place again, due to the effect of 45 ° of fusion points, make pairwise orthogonal line polarisation all with the polarizer 103 optical direction angle at 45 °, as the I-J in Fig. 2, thus interfere on the polarizer 103 optical direction, and interference light intensity enters photodetector 105 by circulator 102, light signal is sent into digital information processing system 106 and is processed after being converted into electric signal, form feedback signal on the one hand and send phase-modulator 104 to, the numeral obtaining magnitude of voltage to be measured on the other hand exports.
To sum up be the complete reflective reciprocity optical voltage transformer course of work based on Pockels effect.