CN1117134A - Testing method for ferroelectric thin film electro-optic coefficient - Google Patents
Testing method for ferroelectric thin film electro-optic coefficient Download PDFInfo
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- CN1117134A CN1117134A CN 94112263 CN94112263A CN1117134A CN 1117134 A CN1117134 A CN 1117134A CN 94112263 CN94112263 CN 94112263 CN 94112263 A CN94112263 A CN 94112263A CN 1117134 A CN1117134 A CN 1117134A
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- thin film
- ferroelectric thin
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Abstract
The testing equipment for ferroelectric film includes optical current receiving system and control system. The receiving system consists of incident light, polariscope, ferroelectric film sample holder, voltage supply, quarter-wavelength plate, magneto-optical modulator, polarization analyzer on high-precision reading disc, alternative signal generator, photomultiplier, oscilloscope and phase-lock amplifier. The control system consists of phase-shift signal obtaining device and motor driver, and the control is completed via keyboard operation. The testing equipment has a minimum measurable double refractivity of 10 to the power -5 and a minimum measurable optical path difference of 0.05 A.
Description
The present invention relates to a kind of testing method for ferroelectric thin film electro-optic coefficient, belong to the ferroelectric thin film field tests.
Ferroelectric thin film is a kind of transparent functional material, has unique electro-optical properties, the variation that under electric field action, can produce optical property, thereby important application prospects is arranged at aspects such as electric light demonstration, storage, switch, modulation.
Electrooptical coefficient is an important parameter of weighing the ferroelectric thin film electro-optical properties, also is the important evidence of thin-film electro optical device design.
Because the thickness of ferroelectric thin film is in micron, sub-micrometer scale, the phase place retardation (optical path difference) that produces under electric field action is minimum, generally only is the magnitude of dust (A), than the same bulk single crystal or little 5 orders of magnitude of ceramic multicrystal body.Therefore can not adopt the existing method of measuring the block materials electrooptical coefficient to come the electrooptical coefficient of MEASUREMENTS OF THIN.There are two kinds of methods to can be used to measure the electrooptical coefficient of ferroelectric thin film according to reported in literature.A kind of is method by report such as H.Adachi, utilize special prism that the elliptically polarized light through film is divided and be situated between into two bundle polarization direction orthogonal components, receive and compare with two on all four photelectric receivers of performance then, to mark electrooptical coefficient.In this method, extremely strict to the requirement of two receivers, the fine difference of any parameter all can cause very big test error, so can only roughly estimate.Another kind method is the photoelastic modulation method of report such as F.Wang, though can record ferroelectric thin film 10
-5The radian phase place is postponed, but the equipment price costliness.
The objective of the invention is to adopt cheap magneto-optic modulator, the light intensity amplitude modulation(PAM) is become phase change, and, can record ferroelectric thin film 10 by computer software and hardware control
-6The small phase place of radian is postponed and being changed, thereby realizes the automatic measurement of ferroelectric thin film electro-optic coefficient.
Ultimate principle of the present invention is to utilize the magneto-optic modulation principle, light signal by ferroelectric thin film is carried out phase modulation (PM), receive photocurrent by common photomultiplier then, the photocurrent that receives is controlled by computer tracking, thus the automatic test of realization ferroelectric thin film photoelectric parameter.This shows that distinguishable high precision angular readings dish and the design of computing machine soft or hard dish to 0.001 is core component of the present invention.
Below in conjunction with embodiment 1 inventive point is described in further detail.Accompanying drawing 1 is the block schematic diagram of photocurrent receiving system in the testing method for ferroelectric thin film electro-optic coefficient provided by the invention.
1-incident light, 2-polarizer
3-tested ferroelectric thin film specimen holder 4-impressed voltage device
5-1/4 slide, 6-magneto-optic modulator
7-analyzer, 8-alternating signal generator
9-photomultiplier, 10-oscillograph
11-lock-in amplifier
When tested film sample was placed on the mutual angle at 45 of added electric field direction on the specimen holder 3 and polarizer 2 and analyzer 7, sample 3 produced birefringence △ n phenomenon under voltage 4 effects.When incident light 1 minute is situated between into the two bundle polarized lights that direction of vibration is orthogonal, the speed of spreading is different by polarizer 2 from the light of sample 3 outgoing, compensate into new polarized light through quarter wave plate 5, its optical path difference is △ n1 (1 is thickness of sample).Polarization direction from the polarization direction of the polarized light of magneto-optic modulator 6 outgoing with respect to incident polarized light has rotated the θ angle.In addition during alternating signal, then cause alternation faraday rotation angle θ ' in the optomagnetic optical modulation 6:
θ’＝θ。Sinωt……(1)
θ in the formula (1).Be the amplitude of alternation faraday rotation angle, ω is for being added in signal angular frequency on the magneto-optic modulator 6.Light intensity then is in the system:
I(α-θ’)＝I。Cos
2(α-θ’)……(2)
α is the angle of polarizer 2 and analyzer 7 polarization directions in the formula (2), I.Be system's light intensity amplitude, the system's light intensity that promptly incides photomultiplier 9 is relevant with the modulation case of the angle of polarizer 2 and analyzer 7 and magneto-optic modulator 6.
If be added in signal one timing on the magneto-optic modulator 6, the system's light intensity that then incides photomultiplier 9 is determined by the angle α between polarizer 2 and the analyzer 7.When α=90 °, the light intensity of system is only modulated by frequency multiplication 2 ω t signals; And α is when departing from 90 °, and then the light intensity of system is by fundamental frequency and frequency multiplication modulation decision.Can be by the departure degree of oscillograph 10 Direct observation or lock-in amplifier 11 quantitative measurement α.Analyzer 7 is placed on the high-precision reading dish, forms a whole.
When ferroelectric thin film 3 produces birefringence △ n under electric field action, cause α to depart from 90 °, then by rotation analyzer 7 a certain angle δ, make on oscillograph 10 or the lock-in amplifier 11 the frequency multiplication component only to occur, then electrooptical coefficient (λ is an optical source wavelength) this moment that can calculate measured material by △ n1=λ/2 π δ, just a test process and data processing were finished by computer control system 12.
Fig. 2 is a computer control system of the present invention, and the interface hardware of this system is partly formed by two: phase displacement signal obtains the driving with step motor.Send into the input end of number-Mo conversion A/D mouth 13 from the phase displacement signal of lock-in amplifier 11, under specific software 18 controls, phase displacement signal can be taken in, with the phase displacement signal is foundation, numeral mouth 14 is sent in the ♂ variation that is produced under electric field action by sample 3, produce to drive step motor 15 required step direction and stepping pulse signal at the output terminal of numeral mouthful, this signal is through conversion and 15 actions of power amplification 16 rear drive step motor, make analyzer 7 produce small angular displacement, only include the frequency multiplication component thereby reach detected modulation signal, the parameter that records can be calculated by figure and data processing 19, mapping and printing.Whole computer control system 12 can be finished by operation keyboard 17.
Design as the high precision angular readings dish of one of gordian technique of the present invention, must solve the gear both forward and reverse directions and rotate the not good enough problem of closing of carving, adopt tin-phosphor bronze and qualitative carbon steel material as turbine worm, make the better elastic contact is arranged between them, reduce the gap, to reach distinguishable precision to 0.001 °.Owing to adopt the computer control step motor to rotate, realize that step motor whenever takes a step forward and be equivalent to 0.0004 ° of reading dial rotation, thereby the phase place retardation that I is measured reaches 7 * 10
-6Radian guarantees to make the present invention test high precision and be not subjected to surround lighting and temperature effect to have high precision, low cost, easy-operating advantage.
This method of testing is applicable to the test with the electric field change characteristic of the electrooptical coefficient, birefraction of ferroelectric thin film; It is 10 that its I is surveyed birefraction
-5, I photometry path difference is 0.05 dust.
Claims (2)
1. method that is used to test ferroelectric thin film electro-optic coefficient is characterized in that being made up of photocurrent receiving system and control system two parts:
(1) receiving system by incident light (1), polarizer (2), tested ferroelectric thin film specimen holder (3), impressed voltage device (4), quarter wave plate (5), magneto-optic modulator (6), be placed on analyzer (7), alternating signal generator (8), photomultiplier (9) on the high-precision reading dish, oscillograph (10) and lock-in amplifier (11) are formed;
(2) interface hardware of control system is obtained by phase displacement signal and drives two parts with step motor and form; Send into the input end of number-mould conversion A/D mouth (13) from the phase displacement signal of lock-in amplifier (11), under specific software (18) control, take in phase displacement signal, on this basis, to change by the δ that sample (3) produce under electric field action and send into numeral mouthful (14), output terminal at the numeral mouth produces required step direction and the stepping pulse signal of driving step motor (15), this signal is through conversion and power amplification (16) rear drive step motor (15) action, make analyzer (7) produce small angular displacement, calculate by figure and data processing (19), mapping, print; Just a computer control system (12) can be finished by operation keyboard (17).
2. by the described method of testing of claim 1, it is characterized in that high-precision reading dish (7) is to adopt tin-phosphor bronze and the qualitative carbon steel material as turbine worm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94112263 CN1049495C (en) | 1994-08-16 | 1994-08-16 | Testing method for ferroelectric thin film electro-optic coefficient |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94112263 CN1049495C (en) | 1994-08-16 | 1994-08-16 | Testing method for ferroelectric thin film electro-optic coefficient |
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| Publication Number | Publication Date |
|---|---|
| CN1117134A true CN1117134A (en) | 1996-02-21 |
| CN1049495C CN1049495C (en) | 2000-02-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 94112263 Expired - Fee Related CN1049495C (en) | 1994-08-16 | 1994-08-16 | Testing method for ferroelectric thin film electro-optic coefficient |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101776709B (en) * | 2010-01-15 | 2012-04-04 | 苏州大学 | Measurement method used for characterizing light current of ferroelectric film |
| CN102621110A (en) * | 2012-03-13 | 2012-08-01 | 中国科学院上海光学精密机械研究所 | Electrooptic coefficient measuring device |
| CN102621072A (en) * | 2012-03-29 | 2012-08-01 | 中国科学院光电技术研究所 | Polarization and birefringence measurement system |
| CN105353088A (en) * | 2015-11-12 | 2016-02-24 | 湖北大学 | Electrically controlled light scattering material and device time-domain response characteristic testing method |
| CN106841041A (en) * | 2017-04-01 | 2017-06-13 | 电子科技大学 | A kind of device and method for measuring thin-film material electro-optic coefficient |
| CN111398218A (en) * | 2020-03-23 | 2020-07-10 | 西安交通大学 | Effective electro-optic coefficient measuring device and method based on magneto-optic detection |
-
1994
- 1994-08-16 CN CN 94112263 patent/CN1049495C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101776709B (en) * | 2010-01-15 | 2012-04-04 | 苏州大学 | Measurement method used for characterizing light current of ferroelectric film |
| CN102621110A (en) * | 2012-03-13 | 2012-08-01 | 中国科学院上海光学精密机械研究所 | Electrooptic coefficient measuring device |
| CN102621072A (en) * | 2012-03-29 | 2012-08-01 | 中国科学院光电技术研究所 | Polarization and birefringence measurement system |
| CN102621072B (en) * | 2012-03-29 | 2013-11-06 | 中国科学院光电技术研究所 | Polarization and birefringence measurement system |
| CN105353088A (en) * | 2015-11-12 | 2016-02-24 | 湖北大学 | Electrically controlled light scattering material and device time-domain response characteristic testing method |
| CN106841041A (en) * | 2017-04-01 | 2017-06-13 | 电子科技大学 | A kind of device and method for measuring thin-film material electro-optic coefficient |
| CN111398218A (en) * | 2020-03-23 | 2020-07-10 | 西安交通大学 | Effective electro-optic coefficient measuring device and method based on magneto-optic detection |
| CN111398218B (en) * | 2020-03-23 | 2021-10-08 | 西安交通大学 | Effective electro-optic coefficient measuring device and method based on magneto-optic detection |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1049495C (en) | 2000-02-16 |
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