CN115598428A - All-fiber integrated electro-optic crystal electric field probe and demodulation device - Google Patents
All-fiber integrated electro-optic crystal electric field probe and demodulation device Download PDFInfo
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- CN115598428A CN115598428A CN202211300498.4A CN202211300498A CN115598428A CN 115598428 A CN115598428 A CN 115598428A CN 202211300498 A CN202211300498 A CN 202211300498A CN 115598428 A CN115598428 A CN 115598428A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/12—Measuring electrostatic fields or voltage-potential
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/241—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using electro-optical modulators, e.g. electro-absorption
Abstract
The invention discloses an all-fiber integrated electro-optic crystal electric field probe and a demodulation device, wherein the electro-optic crystal electric field probe comprises: the polarization maintaining optical fiber comprises a first glass sleeve, a second glass sleeve, a collimating lens, a 1/4 wave plate, an electro-optic crystal and a reflecting film polarization maintaining optical fiber, wherein the first glass sleeve is fixedly connected with the first glass sleeve, the first glass sleeve is fixedly connected with the second glass sleeve, the polarization maintaining optical fiber is connected with the collimating lens, the collimating lens is connected with the 1/4 wave plate, the 1/4 wave plate is connected with the electro-optic crystal, and the electro-optic crystal is connected with the reflecting film; the collimating lens and the 1/4 wave plate are arranged in the second glass sleeve. The invention solves the problem of unstable electric field measurement caused by difficult integration, easy vibration, large volume, difficult coupling and the like of the space optical element, and improves the sensitivity and stability of the measuring device.
Description
Technical Field
The invention relates to the technical field of electromagnetic field measurement, in particular to an all-fiber integrated electro-optic crystal electric field probe and a demodulation device.
Background
With the advent of the 5G era and the advent of the internet of things, cloud computing and the like, the requirements for processing chips are faster, wider in bandwidth and higher in integration. Near-field electric field probes, especially non-destructive probes, are important means for characterizing electromagnetic interference (EMI) or electromagnetic compatibility (EMC) performance tests in high-speed chip design, and are important bases for evaluating device reliability. On the other hand, electrostatic Discharge (EDS) and exposure of electronic systems to excessive electrical stress (EOS) are one of the important causes of device destruction and performance degradation. Therefore, the development of a high-sensitivity and high-spatial-resolution miniature electric field sensor is extremely important for improving the detection efficiency of related micro devices and ensuring the safety of the devices.
The traditional electric field measurement method is that the frequency response of an electrical metal probe is a resonance type which typically supports a standing wave structure, the frequency response is uneven, so that the measurement of broadband signals has locality, the detection of a 5G high-speed chip with high integration degree has locality, and the metal electric field probe has low measurement fidelity due to scattering through the metal probe and coupling with a near-field electric field to be measured, so that great uncertainty is brought to an electric field to be measured. The metal wire can cause the distortion and the disturbance of the field to be measured, and is related to the parameters of the probe, and the correction is difficult to be carried out through subsequent generalized processing, so the measurement has inaccuracy.
The electro-optical electric field sensor of the optical method comprises a system which is usually free of active electronic equipment or power supply, and is usually made of all-dielectric electro-optical crystal, so that the electro-optical electric field sensor has great advantages in measurement accuracy and broadband measurement due to the natural non-electromagnetic crosstalk characteristic. Because the optical fiber network formed by the electro-optical modulator usually contains no metal, the electro-optical modulator is free from electromagnetic interference, has little disturbance to an electric field to be measured, and has flat frequency response.
The probe is connected to a collimator through an optical fiber, a polaroid, an electro-optic crystal, a 1/8 wave plate and a reflector are assembled in the middle of a quartz tube, and finally the quartz tube is sealed by a quartz cylinder to form a sleeve seal. However, such electric field sensors introduce assembly complexity due to the integration of more optical elements within the probe head, and increase the insertion loss of the device. The temperature effect caused by the natural birefringence of the crystal in the probe can cause the drift of the working point of the system, which affects the electric field test, and the problem that the temperature change of the optical fiber can cause the drift of the sensitive working point of the system can not be solved under the configuration.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention provides an all-fiber integrated electro-optic crystal electric field probe and a demodulation device, solves the problem of unstable electric field measurement caused by difficult integration, easy vibration, large volume, difficult coupling and the like of a space optical element, and improves the sensitivity and stability of a measurement device.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an all-fiber integrated electro-optic crystal electric field probe, which comprises: the polarization maintaining optical fiber comprises a first glass sleeve, a second glass sleeve, a collimating lens, a 1/4 wave plate, an electro-optic crystal and a reflecting film;
the polarization maintaining optical fiber is fixedly connected with a first glass sleeve, the first glass sleeve is fixedly connected with a second glass sleeve, the polarization maintaining optical fiber is connected with a collimating lens, the collimating lens is connected with a 1/4 wave plate, the 1/4 wave plate is connected with an electro-optic crystal, and the electro-optic crystal is connected with a reflecting film;
the collimating lens and the 1/4 wave plate are arranged in the second glass sleeve.
As a preferable technical scheme, the pipe diameter of the first glass sleeve is larger than that of the second glass sleeve.
As a preferred technical scheme, filling gaps are arranged among the collimating lens, the 1/4 wave plate and the second glass sleeve, and the filling gaps are filled with ultraviolet glue.
As a preferable technical scheme, the included angle of the polarization maintaining axes of the 1/4 wave plate and the polarization maintaining optical fiber is 45 degrees.
As a preferable technical scheme, the electro-optical crystal adopts any one of a lithium niobate crystal, a lithium tantalate crystal, a zinc telluride crystal and a bismuth silicate crystal.
As a preferred technical scheme, the lithium niobate crystal or lithium tantalate crystal is tangentially transversely cut to form a transverse electric field probe which is cubic in shape.
The invention also provides a control method of the all-fiber integrated electro-optic crystal electric field probe, which comprises the following steps:
the polarization maintaining fiber transmits the polarized light to the collimating lens, the collimating lens focuses the polarized light, the polarized light is changed into circularly polarized light through the 1/4 wave plate, the circularly polarized light passes through the electro-optical crystal of which the refractive index is modulated by an electric field, different phase differences are generated between the light in two orthogonal polarization directions, and the modulated light signal returns to the electro-optical crystal, the 1/4 wave plate and the collimating lens through the reflecting film and is finally output through the fiber.
As a preferred technical scheme, the all-fiber integrated electro-optic crystal electric field probe is provided with: the device comprises a laser, a circulator, an adapter, a polarization controller, a beam splitter, a first polarization beam splitter, a second polarization beam splitter, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a fourth photoelectric detector and a terminal processor;
the laser is connected with the circulator, the circulator is connected with the adapter, the adapter is connected with the electro-optic crystal electric field probe through a polarization maintaining optical fiber, the circulator is also connected with the polarization controller, the polarization controller is connected with the beam splitter, the beam splitter is respectively connected with the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter is respectively connected with the first photoelectric detector and the second photoelectric detector, and the second polarization beam splitter is respectively connected with the third photoelectric detector and the fourth photoelectric detector;
and the first photoelectric detector and the second photoelectric detector are connected with the terminal processor.
The invention also provides a control method of the demodulation device of the all-fiber integrated electro-optic crystal electric field probe, which comprises the following steps:
the laser generates linearly polarized light, the polarized light is input to the electro-optic crystal electric field probe through the circulator and the adapter, the circulator inputs the polarized light returned by the electro-optic crystal electric field probe to the polarization controller, the electric field to be measured modulates the refractive index of the electro-optic crystal through the linear electro-optic effect, and a signal reflected by the electro-optic crystal probe carries a polarization state signal modulated by the electric field;
the polarization controller adjusts the polarization state working point of the polarization state signal, the adjusted polarization state signal respectively enters the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter and the second polarization beam splitter both split light, the first polarization beam splitter or the second polarization beam splitter divides the light into two paths, the first polarization beam splitter decomposes the light signal, the first photoelectric detector and the second photoelectric detector perform photoelectric conversion, the third photoelectric detector and the fourth photoelectric detector convert the received light signal into an electric signal, a difference signal between the first polarization beam splitter and the second polarization beam splitter is output to the terminal processor as a feedback signal, and the terminal processor outputs the difference signal as an electric field signal to be detected.
As a preferred technical scheme, the refractive index of an electro-optic crystal is modulated by an electric field to be measured through a linear electro-optic effect, and the method specifically comprises the following steps:
polarization maintaining fiber transmits polarized light to a collimating lens, the collimating lens focuses the polarized light, the polarized light is changed into circularly polarized light through a 1/4 wave plate, the circularly polarized light passes through an electro-optical crystal subjected to electric field modulation of refractive index, and different phase differences are generated between the light in two orthogonal polarization directions, specifically represented as:
wherein, Δ Φ 0 Expressed as the natural birefringence phase difference, Δ Φ, of the crystal E Expressed as the phase difference caused by the applied electric field, d the effective length of the polarization state through the crystal, an o And Δ n e The refractive index difference of o light and the refractive index difference of e light after the crystal is modulated by an external electric field are respectively, and lambda represents the wavelength of the detected light;
the first photoelectric detector and the second photoelectric detector respectively detect the optical power P of the orthogonal electric field component 1 And optical power P 2 To convert the optical power P 1 And optical power P 2 As the output of the demodulating meansP out Specifically, it is represented as:
wherein E represents an external electric field, and delta K represents a sensitivity matrix of the crystal;
converting the received optical signals into electric signals by using a third photoelectric detector and a fourth photoelectric detector, and outputting a differential signal of the third photoelectric detector and the fourth photoelectric detector to a terminal processor as a feedback signal;
and monitoring a static working point by detecting whether the feedback signal is zero, inputting an electric signal to a polarization controller by a terminal processor, and adjusting the polarization state to the optimal working point by the polarization controller.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) The invention adopts the metal-free electric field measuring probe, and the probe has the advantages of high fidelity, high spatial resolution, wide detection radio frequency band, small volume, strong anti-interference capability and the like, provides extremely high measuring precision and fidelity, and improves the measuring performance.
(2) The first glass sleeve and the second glass sleeve are arranged and used for fixing the internal optical element, so that the effect of reinforcing the whole probe structure is achieved, and the effect of preventing external disturbance is achieved.
(3) Each optical element in the electro-optic crystal electric field probe is fixed by ultraviolet glue, so that the small insertion loss of the device is ensured.
(4) The invention can select and configure the electro-optical crystal with different size length and shape, best meets the requirements of the sensitivity and the frequency bandwidth of the electro-optical crystal probe, and the electro-optical crystal electric field probe can obtain stronger electro-optical signals by matching with different crystal lengths.
(2) The invention adopts the technical scheme of full-optical-fiber integrated polarization state demodulation, the arranged first polarization beam splitter and the second polarization beam splitter divide detection light into two orthogonal linearly polarized light, and the two linearly polarized light are respectively sent into the corresponding photoelectric detectors, one path is used for detecting the polarization state, and the other path is used for feeding back a signal, thereby solving the problem that the working point of the sensor is interfered by external environment (temperature, vibration and the like) in practical application, and improving the sensitivity and the stability of measurement.
Drawings
FIG. 1 is a schematic structural diagram of an all-fiber integrated electro-optic crystal electric field probe according to the present invention;
FIG. 2 is a schematic diagram showing the functional relationship between the electro-optic signal and the electric field amplitude when the electro-optic crystal electric field probe of the present invention is matched with different crystals with different lengths;
FIG. 3 is a schematic structural diagram of a demodulation apparatus of an all-fiber integrated electro-optic crystal electric field probe according to the present invention.
101-polarization maintaining optical fiber, 102-fixing glue, 103-first glass sleeve, 104-second glass sleeve, 105-collimating lens, 106-1/4 wave plate, 107-electro-optic crystal and 108-reflecting film;
201-laser, 202-circulator, 203-adapter, 204-electro-optic crystal electric field probe, 205-terminal processor, 206-polarization controller, 207-beam splitter, 208-first polarization beam splitter, 209-second polarization beam splitter, 210-first photodetector, 211-second photodetector, 212-third photodetector, 213-fourth photodetector;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in fig. 1, the present embodiment provides an all-fiber integrated electro-optic crystal electric field probe, which can detect the amplitude and vector direction of an electric field, and sequentially comprises: a polarization maintaining optical fiber 101, a fixing glue 102, a first glass sleeve 103, a second glass sleeve 104, a collimating lens 105, a 1/4 (quarter wave plate) 106, an electro-optic crystal 107 and a reflecting film 108;
the polarization maintaining optical fiber 101 is fixedly connected with a first glass sleeve 103 through fixing glue 102, the first glass sleeve 103 is fixedly connected with a second glass sleeve 104 through ultraviolet glue, and the pipe diameter of the first glass sleeve 103 is larger than that of the second glass sleeve 104;
the polarization maintaining optical fiber 101 is connected with a collimating lens 105, the collimating lens 105 is connected with a 1/4 wave plate 106, the 1/4 wave plate 106 is connected with an electro-optical crystal 107, and the electro-optical crystal 107 is connected with a reflecting film 108;
the collimating lens 105 and the 1/4 wave plate 106 are arranged in the second glass sleeve 104, and gaps among the collimating lens 105, the 1/4 wave plate 106 and the second glass sleeve 104 are filled with ultraviolet glue to play a role in fixing the collimating lens and the 1/4 wave plate;
in this embodiment, the polarization maintaining fiber is used for transmitting polarized light, and the first glass sleeve and the second glass sleeve are used for fixing the internal optical element, so as to reinforce the whole probe structure and prevent external disturbance;
the collimating lens collimates the detection light and focuses the detection light, the 1/4 wave plate generates circularly polarized light for adjusting a working point, the electro-optic crystal is used for inducing an electric field signal and modulating the polarization state of the light, and the reflecting film reflects the polarized light to integrally form a reflecting probe structure;
in the embodiment, the included angle of the polarization maintaining axes of the 1/4 wave plate and the polarization maintaining optical fiber is preferably 45 degrees;
in the embodiment, each optical element in the electro-optic crystal electric field probe is fixed by ultraviolet glue, so that the small insertion loss of the device is ensured;
in the embodiment, the measurement process of the electro-optic crystal electric field probe is as follows: the collimating lens focuses the polarized light, the incident linearly polarized light is changed into circularly polarized light through the 1/4 wave plate in the electric field probe, after the circularly polarized light passes through the electric field sensitive material electro-optical crystal (i.e. the electro-optical crystal with refractive index modulated by the electric field), the light in two orthogonal polarization directions generates different phase differences, so that the output of the light is changed into different elliptically polarized light along with the size and direction of the electric field signal, and the modulated light signal returns to the electro-optical crystal, the 1/4 wave plate, the collimating lens through the reflecting film and finally enters the demodulating device through the optical fiber.
In the embodiment, the electro-optical crystal has multiple choices, different electro-optical crystals have different electro-optical coefficients, and the size length and the shape of the crystal can be selected according to the requirements of different measurement dynamic ranges, spatial resolutions and the like.
The electro-optical crystal is according to the crystal kind, tangential difference, and the probe divide into horizontal electro-optical probe and vertical electro-optical probe, and tangential, electro-optical coefficient and size structure etc. have decided the sensitivity and the frequency bandwidth of electro-optical crystal probe, according to sensitivity needs, can select the electro-optical crystal of different size length, and the selection of specific electro-optical crystal includes:
selecting lithium niobate or lithium tantalate crystal as anisotropic crystal, transversely cutting X-cut in tangential direction, transverse electric field probe in cubic shape with cross section size of 2-10mm 2 The length can reach 30mm at most. The lithium niobate crystal can measure the electric field components of two orthogonal axes (y-axis and z-axis directions) in a plane by rotating 90 degrees in the plane;
or zinc telluride (ZnTe) crystal is selected, the zinc telluride crystal is isotropic crystal, the tangential direction is <111> -cut, the shape is columnar, the size thickness is 1-5mm, the diameter is 2-10mm, and vector measurement can be carried out;
or Bismuth Silicate (BSO) crystal is selected, the bismuth silicate crystal is isotropic crystal, and <100> -cut or <111> -cut can be used in the tangential direction. The probe is a longitudinal probe when the probe is <100> -cut, and is a transverse probe when the probe is <111> -cut, the probe is cylindrical in shape, the thickness of the size is 2-10mm, the diameter can be selected to be 1-5mm, and the electric field components in two axial directions can be measured simultaneously.
As shown in fig. 2, the functional relationship of the electro-optical signal with the electric field amplitude is obtained when different crystals of the electro-optical crystal electric field probe are matched with different crystal lengths, which indicates that under the same electric field strength to be measured, the crystal length is increased, and a stronger electro-optical signal can be obtained; the crystal material with larger electro-optic coefficient is selected, and the electro-optic signal can also be enhanced.
Example 2
As shown in fig. 3, the present embodiment provides a demodulation apparatus for an all-fiber integrated electro-optic crystal electric field probe, which is provided with the electro-optic crystal electric field probe of embodiment 1, which is marked as an electro-optic crystal electric field probe 204, and further includes; a laser 201, a circulator 202, an adapter 203, a polarization controller 206, a beam splitter 207, a first polarization beam splitter 208, a second polarization beam splitter 209, a first photodetector 210, a second photodetector 211, a third photodetector 212, a fourth photodetector 213, and a terminal processor 205;
the laser 201 is connected with the circulator 202, the circulator 202 is connected with the adapter 203, the adapter 203 is connected with the electro-optic crystal electric field probe 204 through a polarization maintaining optical fiber, the circulator 202 is further connected with the polarization controller 206, the polarization controller 206 is connected with the beam splitter 207, the beam splitter 207 is respectively connected with the first polarization beam splitter 208 and the second polarization beam splitter 209, the first polarization beam splitter 208 is respectively connected with the first photoelectric detector 210 and the second photoelectric detector 211, and the second polarization beam splitter 209 is respectively connected with the third photoelectric detector 212 and the fourth photoelectric detector 213;
the first photodetector 210 and the second photodetector 211 are both connected with the terminal processor 205;
in this embodiment, the laser generates linearly polarized light, the polarized light is input to the electric field probe through the circulator and the adapter, the circulator also inputs the polarized light returned by the electric field probe to the polarization controller, because the electric field to be measured modulates the refractive index of the electro-optic crystal through the linear electro-optic effect, the signal reflected back by the electro-optic crystal probe carries a polarization state signal modulated by the electric field, the polarization controller is used for adjusting the polarization state working point of the polarization state signal, the adjusted polarization state signal respectively enters the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter and the second polarization beam splitter both split the light, the first polarization beam splitter or the second polarization beam splitter splits the light into two paths, the first polarization beam splitter splits the light signal, the first photodetector and the second photodetector perform photoelectric conversion, the third photodetector and the fourth photodetector convert the received light signal into an electrical signal, the differential signal between the two is output to the terminal processor as a differential signal, and the terminal processor outputs the differential signal as the electric field signal to be measured.
In this embodiment, the phase difference between the two orthogonal electric field components of the polarized light due to the optical path difference changes the relevant information of the elliptical polarization, and under the influence of the external electric field, the phase difference between the two orthogonal electric field components is Δ Φ, where:
wherein, Δ Φ 0 Expressed as the natural birefringence phase difference, Δ Φ, of the crystal E Expressed as the phase difference caused by the applied electric field, and d represents the effective length of the polarization state through the crystal. Δ n o And Δ n e The refractive index difference of the o light and the refractive index difference of the e light after the crystal is modulated by an external electric field are respectively, and lambda represents the wavelength of the detection light. Furthermore, a sensitivity matrix delta K for describing the crystal is introduced and is in direct proportion to the electro-optic coefficient of the material, so that the phase difference of two orthogonal electric field components of the reflected light wave is in direct proportion to an electric field to be detected, and the optical power P of the orthogonal electric field components is respectively detected 1 And P 2 From P to P 1 And P 2 As the output P of the demodulation means out Then the demodulation apparatus output can be expressed as:
wherein E represents an applied electric field, P 1 And P 2 Corresponding to the outputs of the first and second photodetectors, respectively;
thus, the initial phase Δ Φ is controlled by the polarization controller 0 Where ± pi/4, the demodulation device has the maximum sensitivity, and the demodulation device output can be expressed as:
in practical applications, the sensor needs to work in a linear region of the function, and the functional relationship between the output power and the applied electric field is approximately as follows:
the third photodetector and the fourth photodetector convert the received optical signals into electrical signals, and the differential signal (P) between the optical signals and the electrical signals 3 -P 4 = 0) as a feedback signal to the terminal processor, P 3 、P 4 Corresponding to the outputs of the third and fourth photodetectors, respectively;
when the static working point is under the condition of external electric field E =0, the device outputs P out And =0, therefore, the static operating point can be monitored by judging whether the output signal of the feedback branch is zero or not, the static operating point of the detection branch is adjusted by the feedback branch, and meanwhile, the temperature and vibration interference can be eliminated by monitoring P3-P4=0 during the measurement of the electric field.
The polarization controller of this embodiment adjusts the polarization controller at the front end of the measurement branch (based on the measurement branch formed by the first polarization beam splitter, the first photodetector, and the second photodetector) and the feedback branch (based on the feedback branch formed by the second polarization beam splitter, the third photodetector, and the fourth photodetector), and can simultaneously affect two polarization states, and adjust the working point to be the static working point of the device, and the alternating-current electric field signal is not affected by temperature, vibration, and the like.
The static working point of the demodulation device can change along with external reasons such as temperature or mechanical vibration, the first polarization beam splitter and the second polarization beam splitter of the embodiment divide detection light into two linearly polarized light which are orthogonal to each other and respectively sent to corresponding photoelectric detectors, and the first photoelectric detector and the second photoelectric detector of the embodiment are used for detecting the polarization state and converting polarization state signals modulated by an electric field into readable electric signals; the third and fourth photodetectors are used for feeding back signals, and whether the output signals through the feedback branch are zero or not can monitor the static working point, so that the effect of monitoring whether the static working point drifts or not is achieved.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. An all-fiber integrated electro-optic crystal electric field probe, comprising: the polarization maintaining optical fiber comprises a first glass sleeve, a second glass sleeve, a collimating lens, a 1/4 wave plate, an electro-optic crystal and a reflecting film;
the polarization maintaining optical fiber is fixedly connected with a first glass sleeve, the first glass sleeve is fixedly connected with a second glass sleeve, the polarization maintaining optical fiber is connected with a collimating lens, the collimating lens is connected with a 1/4 wave plate, the 1/4 wave plate is connected with an electro-optic crystal, and the electro-optic crystal is connected with a reflecting film;
the collimating lens and the 1/4 wave plate are arranged in the second glass sleeve.
2. The all-fiber integrated electro-optic crystal electric field probe of claim 1, wherein the tube diameter of the first glass sleeve is larger than the tube diameter of the second glass sleeve.
3. The all-fiber integrated electro-optic crystal electric field probe of claim 1, wherein filling gaps are arranged among the collimating lens, the 1/4 wave plate and the second glass sleeve, and the filling gaps are filled with ultraviolet glue.
4. The all-fiber integrated electro-optic crystal electric field probe of claim 1, wherein the included angle between the polarization-maintaining axes of the 1/4 wave plate and the polarization-maintaining fiber is 45 degrees.
5. The all-fiber integrated electro-optic crystal electric field probe of claim 1, wherein the electro-optic crystal is any one of a lithium niobate crystal, a lithium tantalate crystal, a zinc telluride crystal and a bismuth silicate crystal.
6. The all-fiber integrated electro-optic crystal electric field probe of claim 5, wherein the lithium niobate crystal or lithium tantalate crystal is cross-cut in a tangential direction to form a lateral electric field probe in a cubic shape.
7. The method for controlling the all-fiber integrated electro-optic crystal electric field probe according to any one of claims 1-6, comprising the steps of:
the polarization maintaining fiber transmits the polarized light to the collimating lens, the collimating lens focuses the polarized light, the polarized light is changed into circularly polarized light through the 1/4 wave plate, the circularly polarized light passes through the electro-optical crystal of which the refractive index is modulated by an electric field, different phase differences are generated between the light in two orthogonal polarization directions, and the modulated light signal returns to the electro-optical crystal, the 1/4 wave plate and the collimating lens through the reflecting film and is finally output through the fiber.
8. An all-fiber integrated electro-optic crystal electric field probe demodulation device, characterized in that the all-fiber integrated electro-optic crystal electric field probe of any one of claims 1 to 6 is provided, further comprising: the device comprises a laser, a circulator, an adapter, a polarization controller, a beam splitter, a first polarization beam splitter, a second polarization beam splitter, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a fourth photoelectric detector and a terminal processor;
the laser is connected with the circulator, the circulator is connected with the adapter, the adapter is connected with the electro-optic crystal electric field probe through a polarization maintaining optical fiber, the circulator is also connected with the polarization controller, the polarization controller is connected with the beam splitter, the beam splitter is respectively connected with the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter is respectively connected with the first photoelectric detector and the second photoelectric detector, and the second polarization beam splitter is respectively connected with the third photoelectric detector and the fourth photoelectric detector;
and the first photoelectric detector and the second photoelectric detector are connected with the terminal processor.
9. The method for controlling the demodulation device of the all-fiber integrated electro-optic crystal electric field probe according to claim 8, comprising the steps of:
the laser generates linearly polarized light, the polarized light is input to the electro-optic crystal electric field probe through the circulator and the adapter, the circulator inputs the polarized light returned by the electro-optic crystal electric field probe to the polarization controller, the electric field to be measured modulates the refractive index of the electro-optic crystal through the linear electro-optic effect, and a signal reflected by the electro-optic crystal probe carries a polarization state signal modulated by the electric field;
the polarization controller adjusts the polarization state working point of the polarization state signal, the adjusted polarization state signal respectively enters the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter and the second polarization beam splitter both split light, the first polarization beam splitter or the second polarization beam splitter divides the light into two paths, the first polarization beam splitter decomposes the light signal, the first photoelectric detector and the second photoelectric detector perform photoelectric conversion, the third photoelectric detector and the fourth photoelectric detector convert the received light signal into an electric signal, a difference signal between the first polarization beam splitter and the second polarization beam splitter is output to the terminal processor as a feedback signal, and the terminal processor outputs the difference signal as an electric field signal to be detected.
10. The method for controlling the demodulation device of the all-fiber integrated electro-optic crystal electric field probe according to claim 9, wherein the refractive index of the electro-optic crystal is modulated by the electric field to be measured through a linear electro-optic effect, and the method comprises the following steps:
polarization maintaining fiber transmits polarized light to a collimating lens, the collimating lens focuses the polarized light, the polarized light is changed into circularly polarized light through a 1/4 wave plate, the circularly polarized light passes through an electro-optic crystal subjected to electric field modulation of refractive index, and different phase differences are generated between the light in two orthogonal polarization directions, specifically expressed as follows:
wherein, Δ Φ 0 Expressed as the natural birefringence phase difference, Δ Φ, of the crystal E Expressed as the phase difference caused by the applied electric field, d the effective length of the polarization state through the crystal, an o And Δ n e The refractive index difference of o light and the refractive index difference of e light after the crystal is modulated by an external electric field are respectively, and lambda represents the wavelength of the detected light;
the first photodetector and the second photodetector respectively detect the optical power P of the orthogonal electric field components 1 And optical power P 2 To convert the optical power P 1 And optical power P 2 As the output P of the demodulation means out Specifically, it is represented as:
wherein E represents an external electric field, and delta K represents a sensitivity matrix of the crystal;
converting the received optical signals into electric signals by using a third photoelectric detector and a fourth photoelectric detector, and outputting differential signals of the third photoelectric detector and the fourth photoelectric detector to a terminal processor as feedback signals;
and monitoring a static working point by detecting whether the feedback signal is zero, inputting an electric signal to a polarization controller by a terminal processor, and adjusting the polarization state to the optimal working point by the polarization controller.
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| CN202211300498.4A CN115598428A (en) | 2022-10-24 | 2022-10-24 | All-fiber integrated electro-optic crystal electric field probe and demodulation device |
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| CN202211300498.4A CN115598428A (en) | 2022-10-24 | 2022-10-24 | All-fiber integrated electro-optic crystal electric field probe and demodulation device |
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