Amplitude measurement error correction system and method for electro-optical sampling system

Abstract

The invention belongs to the technical field of electro-optical measurement, and particularly discloses an amplitude measurement error correction system and method for an electro-optical sampling system, and the system comprises a femtosecond laser which is used for outputting an ultrafast laser pulse as sampling light; the polarizer is used for converting the sampling light into linearly polarized light and transmitting the linearly polarized light to the coplanar waveguide; the fixed amplitude signal source is used for transmitting an output stable voltage signal to the coplanar waveguide; the coplanar waveguide is used for enabling the linearly polarized light to generate polarization state change under the action of the stable voltage signal, forming light with the polarization state change and transmitting the light to the non-polarization beam splitter; the non-polarization beam splitter is used for splitting the light with the changed polarization state into two light beams, one light beam is input to a photoelectric detector A through the polarization analyzer A, and the other light beam is input to a photoelectric detector B through the quarter-wave plate and the polarization analyzer B; and the signal acquisition and processing module is used for performing error correction on data output by the photoelectric detector A and the photoelectric detector B.

Description

Technical Field

[0001] The invention belongs to the technical field of electro-optical measurement, and in particular relates to an amplitude measurement error correction system and method for an electro-optical sampling system. Background Art

[0002] Compared with traditional electrical measurement methods, electro-optical sampling measurement technology is not limited by the bandwidth of the measuring instrument, nor is it affected by the external electromagnetic environment. It can achieve frequency reduction sampling and has the advantages of small time resolution and small measurement uncertainty. Therefore, electro-optical sampling systems are widely used in the measurement of multiple parameters such as the waveform and amplitude of ultra-high-speed pulse signals, high-voltage signals, terahertz signals, and communication signals, thereby realizing the characterization of key indicators of instruments and equipment such as ultra-high-speed pulse generators, spectrum analysis in the field of wireless communications, and ranging. As the requirements for signal stability in such applications gradually increase, higher requirements are also placed on the reliability and accuracy of the corresponding measurement methods.

[0003] Any measurement method has measurement errors. For the amplitude measurement of the electro-optical sampling system, based on the principle of converting the polarization state change into light intensity for measurement, the alignment of the polarization axis of the optical components related to the polarization state in the system directly affects the accuracy of the measured amplitude. The half-wave voltage of the electro-optical crystal also limits the range of the amplitude that can be measured by the system. The system can only measure the amplitude change within a half-wave voltage range. Therefore, it is urgent to propose an amplitude measurement error correction system and method for the electro-optical sampling system to solve the above technical problems. Summary of the invention

[0004] The present invention provides an amplitude measurement error correction system and method for an electro-optical sampling system, which is used to solve the problem of inaccurate amplitude measurement caused by the inability to fully align the optical axis angles of optical elements such as electro-optical crystals and the uneven vertical polarization component and horizontal polarization component of the light beam split by a non-polarization beam splitter.

[0005] In a first aspect, a system for correcting amplitude measurement errors of an electro-optical sampling system is provided, the system comprising:

[0006] Femtosecond laser, polarizer, amplitude stabilization signal source, coplanar waveguide, non-polarizing beam splitter, quarter wave plate, analyzer A, photodetector A, analyzer B, photodetector B and signal acquisition and processing module; Among them,

[0007] The femtosecond laser is used to output ultrafast laser pulses as sampling light;

[0008] The polarizer is used to convert the sampling light into linearly polarized light and transmit it to the coplanar waveguide;

[0009] The stable amplitude signal source is used to transmit the output stable voltage signal to the coplanar waveguide;

[0010] The coplanar waveguide is used to make the linearly polarized light change its polarization state under the action of the stable voltage signal, so as to form light with changed polarization state and transmit it to the non-polarizing beam splitter;

[0011] The non-polarizing beam splitter is used to split the light with a changed polarization state into a first light beam and a second light beam, and transmit the first light beam to the polarizer A and input it to the photodetector A, and transmit the second light beam to the polarizer B through the quarter-wave plate and input it to the photodetector B;

[0012] The signal acquisition and processing module is used to perform error correction on the data output by the photodetector A and the photodetector B.

[0013] In a second aspect, a method for correcting amplitude measurement errors of an electro-optical sampling system is provided, the method comprising:

[0014] The femtosecond laser outputs linearly polarized light at 45° to the y and z axes of the coplanar waveguide substrate electro-optical crystal through a polarizer;

[0015] The linearly polarized light passes through the gap between the coplanar waveguide signal electrode and the ground electrode, undergoes a polarization state change under the action of a stable voltage signal generated by a stable amplitude signal source, and is then transmitted to a non-polarizing beam splitter, where it is split into a first light beam and a second light beam.

[0016] The first light beam is collected by the photodetector A after passing through the analyzer A. The ratio of the collected signal power to the total power of the first light beam is calculated by the signal collection processing module to obtain a transmittance.

[0017] The second beam is collected by the photodetector B after passing through the quarter wave plate and the analyzer B. The ratio of the collected signal power to the total power of the second beam is calculated by the signal acquisition processing module to obtain the second transmittance.

[0018] Change the output signal voltage amplitude value of the stable amplitude signal source to obtain multiple groups Multiple groups Perform ellipse fitting to obtain the ellipse equation;

[0019] Taking the coordinates of the must-pass point (1, 0.5) as the fixed point, the ellipse equation is mapped to the standard circle equation through axis transformation to obtain the corresponding error correction value (T A ', T B '), the mapping coefficient is the error correction factor;

[0020] The amplitude-stabilized signal source is replaced by the signal to be measured, and the error correction factor is used to implement the error correction of the amplitude measurement of the signal to be measured.

[0021] An embodiment of the present invention provides an amplitude measurement error correction system and method for an electro-optical sampling system. In combination with an ideal measurement curve of the electro-optical sampling system, system error correction is implemented based on an ellipse fitting method, thereby removing amplitude measurement errors caused by the inability to fully align the optical axis angles of optical elements such as electro-optical crystals and the uneven vertical polarization component and horizontal polarization component of the light beam split by a non-polarizing beam splitter, thereby realizing error correction in the amplitude measurement process.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 A schematic diagram of the structure of an amplitude measurement error correction system for an electro-optical sampling system provided according to an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of implementing error correction based on ellipse fitting and mapping according to an embodiment of the present invention;

[0026] Figure 3 The present invention is a schematic diagram of an implementation flow of an amplitude measurement error correction method for an electro-optical sampling system provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] The technical solutions provided by the embodiments of this specification are described in detail below in conjunction with the accompanying drawings.

[0030] In order to improve the detection accuracy of a signal to be measured, an embodiment of the present invention provides an amplitude measurement error correction system and method for an electro-optical sampling system.

[0031] Figure 1 FIG. 1 is a schematic diagram of a structure of an amplitude measurement error correction system for an electro-optical sampling system according to an embodiment of the present invention. Figure 1 , the system comprising:

[0032] Femtosecond laser, polarizer, amplitude stabilization signal source, coplanar waveguide, non-polarizing beam splitter, quarter wave plate, analyzer A, photodetector A, analyzer B, photodetector B and signal acquisition and processing module; Among them,

[0033] The femtosecond laser is used to output ultrafast laser pulses as sampling light;

[0034] The polarizer is used to convert the sampling light into linearly polarized light and transmit it to the coplanar waveguide;

[0035] The stable amplitude signal source is used to transmit the output stable voltage signal to the coplanar waveguide;

[0036] The coplanar waveguide is used to make the linearly polarized light change its polarization state under the action of the stable voltage signal, so as to form light with changed polarization state and transmit it to the non-polarizing beam splitter;

[0037] The non-polarizing beam splitter is used to split the light with a changed polarization state into a first light beam and a second light beam, and transmit the first light beam to the polarizer A and input it to the photodetector A, and transmit the second light beam to the polarizer B through the quarter-wave plate and input it to the photodetector B;

[0038] The signal acquisition and processing module is used to perform error correction on the data output by the photodetector A and the photodetector B.

[0039] In a specific implementation, the signal acquisition and processing module is connected to the signal output ends of the photodetectors A and B respectively through cables of the same length to perform error correction on the output data.

[0040] In a specific embodiment,

[0041] The substrate material of the coplanar waveguide is an electro-optical crystal;

[0042] The substrate material uses x-cut LiTaO3 material;

[0043] The electro-optical crystal causes a change in refractive index under the action of the stable voltage signal, thereby causing a change in polarization state of the linearly polarized light passing through the electro-optical crystal.

[0044] In a specific embodiment,

[0045] The polarization axis of the analyzer A is parallel to the polarization axis of the polarizer;

[0046] The polarization axis of the analyzer B is perpendicular to the polarization axis of the polarizer.

[0047] In a specific embodiment,

[0048] The system also includes an input connector;

[0049] The input connector includes a first transmission cable and a first coplanar waveguide probe, the amplitude-stabilized signal source is connected to the first coplanar waveguide probe through the first transmission cable, and the first coplanar waveguide probe is connected to the coplanar waveguide.

[0050] In a specific embodiment,

[0051] The system also includes an output connector and a matching load;

[0052] The output connector includes a second transmission cable and a second coplanar waveguide probe, the matching load is connected to the second coplanar waveguide probe through the second transmission cable, and the second coplanar waveguide needle is connected to the coplanar waveguide to match the impedance of the coaxial end and the coplanar waveguide transmission line to prevent reflection of the transmitted signal.

[0053] In a specific embodiment,

[0054] The system also includes an objective lens, an optical fiber illumination light source and a microscopic imaging system constructed by a CCD, which is used to monitor the state of the coplanar waveguide probe.

[0055] In a specific embodiment,

[0056] The reference signal output end of the femtosecond laser is connected to the reference signal input end of the amplitude stabilization source to maintain signal synchronization.

[0057] An embodiment of the present invention provides an amplitude measurement error correction system for an electro-optical sampling system. In combination with an ideal measurement curve of the electro-optical sampling system, the system error correction is implemented based on an ellipse fitting method, thereby removing the amplitude measurement error caused by the inability to fully align the optical axis angles of optical elements such as electro-optical crystals and the uneven vertical polarization component and horizontal polarization component of the light beam split by a non-polarizing beam splitter, thereby realizing error correction in the amplitude measurement process.

[0058] Based on the same inventive concept, the present invention also provides an amplitude measurement error correction method for an electro-optical sampling system, see Figure 3 , the method comprising:

[0059] S300: The femtosecond laser outputs linear polarized light at 45° to the y and z axes of the coplanar waveguide substrate electro-optical crystal through a polarizer;

[0060] S302: The linearly polarized light passes through the gap between the coplanar waveguide signal electrode and the ground electrode, undergoes a polarization state change under the action of a stable voltage signal generated by a stable amplitude signal source, and is then transmitted to a non-polarizing beam splitter, where it is split into a first light beam and a second light beam;

[0061] S304: The first light beam is collected by the photodetector A after passing through the analyzer A, and the ratio of the collected signal power to the total power of the first light beam is calculated by the signal collection processing module to obtain a transmittance

[0062] S306: The second light beam is collected by the photodetector B after passing through the quarter wave plate and the analyzer B. The signal collection and processing module calculates the ratio of the collected signal power to the total power of the second light beam to obtain the second transmittance.

[0063] S308: Change the voltage amplitude value of the output signal of the stabilizing signal source to obtain multiple groups Multiple groups Perform ellipse fitting to obtain the ellipse equation;

[0064] S310: Taking the coordinates of the must-pass point (1, 0.5) as the fixed point, the ellipse equation is mapped to the standard circle equation through axis transformation to obtain the corresponding error correction value (T A ', T B '), the mapping coefficient is the error correction factor;

[0065] S312: replacing the amplitude-stabilized signal source with the signal to be measured, and using the error correction factor to correct the error of the amplitude measurement of the signal to be measured.

[0066] In a specific implementation, the first transmittance expression is:

[0067]

[0068] The second transmittance expression is:

[0069]

[0070] In the formula, Wherein, V is the signal amplitude output by the stable amplitude signal source, V π is the half-wave voltage of the electro-optical crystal; dδ represents the angle error; t r Represents the proportionality factor.

[0071] Change the output signal voltage amplitude of the stable amplitude signal source to obtain multiple groups of The ellipse equation can be fitted, and the fitted ellipse equation can be used The theoretical ellipse equation expressed in this way is combined with the calculation to obtain the angle error dδ and the proportional coefficient t r The specific value of is used to understand and characterize the specific error characteristics of the system.

[0072] It should be noted that, ideally, V is the signal amplitude (variation value) output by the stable amplitude signal source, V π is the half-wave voltage of the electro-optical crystal (fixed value). As the amplitude of the loading signal changes, T A 、T B Conforms to the standard circular curve distribution.

[0073] The angle error dδ is introduced because the polarization axis of the polarizer and the optical axis of the electro-optical crystal cannot be completely aligned. The proportional coefficient t is introduced by the uneven horizontal and vertical polarization components of the light after the non-polarizing beam splitter splits the light. r (Ideally, t r =1), the actual calculation formulas for the first transmittance and the second transmittance are as follows:

[0074]

[0075]

[0076] In the formula, It conforms to the elliptic curve distribution, and regardless of whether there is an error, the standard circular curve and the elliptic curve pass through the point (1,0.5), see Figure 2 .

[0077] Change the output signal amplitude of the stable amplitude signal source to obtain the Through multiple groups The elliptical curve and equation are obtained by fitting. Through axis transformation and mapping, the long semi-axis of the ellipse is used as the radius of the ideal circle, and the ellipse is converted into a standard circular curve that conforms to the ideal situation. The conversion factor is the error correction factor of the electro-optical system. The steady-amplitude signal source is replaced by the signal to be measured, and the specific The measured points are mapped onto the standard circular curve using the conversion factor (T A ′,T B ′), thereby realizing the error correction of the amplitude measurement of the measured signal and obtaining the voltage value of the measured signal with higher measurement accuracy.

[0078] At the same time, through The combination points can realize the recognition and measurement of amplitude values ​​exceeding the half-wave voltage range. When the signal to be measured has time axis information, the recognition and measurement of amplitude values ​​exceeding twice the half-wave voltage range can also be realized by the rotation direction of the measuring point in the circular curve.

[0079] An embodiment of the present invention provides an amplitude measurement error correction method for an electro-optical sampling system. In combination with an ideal measurement curve of the electro-optical sampling system, system error correction is implemented based on an ellipse fitting method, thereby removing amplitude measurement errors caused by the inability to fully align the optical axis angles of optical elements such as electro-optical crystals and the uneven vertical polarization component and horizontal polarization component of the light beam split by a non-polarizing beam splitter, thereby realizing error correction in the amplitude measurement process.

[0080] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0081] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An amplitude measurement error correction system for an electro-optical sampling system, characterized in that: The system comprises: Femtosecond laser, polarizer, amplitude stabilization signal source, coplanar waveguide, non-polarizing beam splitter, quarter wave plate, analyzer A, photodetector A, analyzer B, photodetector B and signal acquisition and processing module; Among them, The femtosecond laser is used to output ultrafast laser pulses as sampling light; The polarizer is used to convert the sampling light into linearly polarized light and transmit it to the coplanar waveguide; The stable amplitude signal source is used to transmit the output stable voltage signal to the coplanar waveguide; The coplanar waveguide is used to make the linearly polarized light change its polarization state under the action of the stable voltage signal, so as to form light with changed polarization state and transmit it to the non-polarization beam splitter; The non-polarizing beam splitter is used to split the light with a changed polarization state into a first light beam and a second light beam, and transmit the first light beam to the polarizer A and input it to the photodetector A, and transmit the second light beam to the polarizer B through the quarter-wave plate and input it to the photodetector B; The signal acquisition and processing module is used to perform error correction on the data output by the photodetector A and the photodetector B.

2. The system according to claim 1, characterized in that The substrate material of the coplanar waveguide is an electro-optical crystal; The substrate material uses x-cut LiTaO3 material; The refractive index of the electro-optical crystal changes under the action of the stable voltage signal, thereby causing the polarization state of the linearly polarized light passing through the electro-optical crystal to change.

3. The system according to claim 2, characterized in that The polarization axis of the analyzer A is parallel to the polarization axis of the polarizer; The polarization axis of the analyzer B is perpendicular to the polarization axis of the polarizer.

4. The system according to claim 3, characterized in that The system also includes an input connector; The input connector includes a first transmission cable and a first coplanar waveguide probe, the amplitude-stabilized signal source is connected to the first coplanar waveguide probe through the first transmission cable, and the first coplanar waveguide probe is connected to the coplanar waveguide.

5. The system according to claim 4, characterized in that The system also includes an output connector and a matching load; The output connector includes a second transmission cable and a second coplanar waveguide probe, the matching load is connected to the second coplanar waveguide probe through the second transmission cable, and the second coplanar waveguide needle is connected to the coplanar waveguide to match the impedance of the coaxial end and the coplanar waveguide transmission line to prevent reflection of the transmitted signal.

6. The system according to claim 5, characterized in that The system also includes an objective lens, an optical fiber illumination light source and a microscopic imaging system constructed by a CCD, which is used to monitor the state of the coplanar waveguide probe.

7. The system according to claim 6, characterized in that The reference signal output end of the femtosecond laser is connected to the reference signal input end of the amplitude stabilization source to maintain signal synchronization.

8. A method for correcting amplitude measurement errors in an electro-optical sampling system, characterized in that: The amplitude measurement error correction system for an electro-optical sampling system according to any one of claims 1 to 7, the method comprising: The femtosecond laser outputs linearly polarized light at 45° to the y and z axes of the coplanar waveguide substrate electro-optical crystal through a polarizer; The linearly polarized light passes through the gap between the coplanar waveguide signal electrode and the ground electrode, undergoes a polarization state change under the action of a stable voltage signal generated by a stable amplitude signal source, and is then transmitted to a non-polarizing beam splitter, where it is split into a first light beam and a second light beam. The first light beam is collected by the photodetector A after passing through the analyzer A. The ratio of the collected signal power to the total power of the first light beam is calculated by the signal collection processing module to obtain a transmittance. The second beam is collected by the photodetector B after passing through the quarter wave plate and the analyzer B. The ratio of the collected signal power to the total power of the second beam is calculated by the signal acquisition processing module to obtain the second transmittance. Change the output signal voltage amplitude value of the stable amplitude signal source to obtain multiple groups Multiple groups Perform ellipse fitting to obtain the ellipse equation; Taking the coordinates of the necessary point (1, 0.5) as the fixed point, the ellipse equation is mapped to the standard circle equation through axis transformation to obtain the corresponding error correction value (T' A , T' B ), the mapping coefficient is the error correction factor; The amplitude-stabilized signal source is replaced by the signal to be measured, and the error correction factor is used to implement the error correction of the amplitude measurement of the signal to be measured.

9. The method according to claim 8, characterized in that The first transmittance expression is: The second transmittance expression is: In the formula, Wherein, V is the signal amplitude output by the stable amplitude signal source, V π is the half-wave voltage of the electro-optical crystal; dδ represents the angle error; t r Represents the proportionality factor.

10. The method according to claim 9, characterized in that Change the output signal voltage amplitude of the stable amplitude signal source to obtain multiple groups of Fitting the ellipse equation, fitting the ellipse equation and using The theoretical ellipse equation expressed in this way is combined with the calculation to obtain the angle error dδ and the proportional coefficient t r The specific value of is used to characterize the system error characteristics.

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