CN203396695U - Apparatus for magnetic field optical elliptic polarization test by using tunable wavelength laser device - Google Patents

Abstract

The utility model discloses an apparatus for a magnetic field optical elliptic polarization test by using a tunable wavelength laser device, and belongs to the technical field of generalized elliptic polarization tests. The apparatus comprises a laser power supply, a tunable wavelength laser device, an optical path system, an electromagnet, a phase-locked amplifier and a PC (Personal Computer), wherein the optical path system comprises a polarizer, two diaphragms, a chopper, a polarization analyzer, a converging lens, an optical filter, and a photoelectric detector. The apparatus is characterized in that by combination of the tunable wavelength laser device and a magnetic field optical elliptic polarization system, a single wavelength magnetic field optical elliptic polarization test is combined with a multi-wavelength magnetic field optical elliptic polarization test; the laser device can emit lasers with different frequencies based on regulation on the current of the laser power supply, meanwhile, the optical filter which is corresponding to the outgoing laser frequency and is connected with the photoelectric detector in a preposed form is changed, the PC performs multi-wavelength magnetic field optical elliptic polarization test on a magnetic material sample, and can obtain a curve of spectrum of the magneto-optical coupling coefficient of a material. The apparatus is simple and rational in structure, convenient to assemble, high in test accuracy and easy to operate.

Description

Utilize wavelengthtunable laser instrument to carry out the device of Magnetooptic ellipsometry test

Technical field

The utility model relates to a kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test, belongs to broad sense ellipsometry technical field.

Background technology

Along with the widespread use of magnetic material on magneto-optic storage medium and semiconductor devices, the research of magnetic material magneto-optical property is become to very urgent.Magnetooptic ellipsometry measuring technique is the broad sense ellipsometry that a kind of Kerr magnetooptical effect of utilizing magnetic material is carried out ellipsometry, can record refractive index N, extinction coefficient K, magneto-optic coupling coefficient Q of magnetic sample etc.Along with the development of Magnetooptic ellipsometry technology, the measurement of single wavelength cannot meet the demand of research.Magnetooptic ellipsometry technology has very high requirement to light source power stability, but generally the multi-wavelength white light light source stability of application is poor now, if do not carried out other processing, is difficult to meet high-precision experiment measuring.As (author: R.Rauer, G.Neuber, J.Kunze, J. in the article " the spectrum Magnetooptic ellipsometry temperature dependency research of magnetic compound " of delivering on magazine [scientific instrument comment] (76 volume was 023910 page in 2005)

and M.R ü bhausen), author has carried out complicated processing to light source xenon lamp, afterwards 150nm has been carried out Magnetooptic ellipsometry with the permalloy of 60nm and has tested and obtained corresponding magneto-optic coupling coefficient.But the Magnetooptic ellipsometry test for monoatomic layer has had higher requirement to light source stability.Now a kind of rapid and convenient of exigence, light source method that degree of stability is high solve the problems referred to above.

Summary of the invention

The shortcomings and deficiencies that exist in order to overcome prior art, the utility model proposes a kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test.

The technical solution of the utility model realizes in the following manner:

A kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test, comprise Laser Power Devices, wavelengthtunable laser instrument, light path system, electromagnet, lock-in amplifier and PC, it is characterized in that light path system comprises the polarizer, two diaphragms, chopper, analyzer, condenser, optical filter and photodetectors, Laser Power Devices are connected with wavelengthtunable laser instrument, by regulating the electric current of Laser Power Devices can make the laser of laser emitting different frequency; Chopper is connected with lock-in amplifier; Before wavelengthtunable laser instrument is positioned at the polarizer, by the polarizer, starts to prolong light path and be sequentially arranged as two diaphragms, chopper, analyzer, condenser, optical filter and photodetectors; Between two diaphragms, place sample stage, sample stage is positioned in the middle of electromagnet; The output terminal of photodetector is connected to the input end of lock-in amplifier, and the output terminal of lock-in amplifier is connected to PC, with observed and recorded computation and measurement result.

Described photodetector is silicon photocell detector, and the mode being installed by trim ring connects preposition optical filter.

Described wavelengthtunable laser instrument is that output wavelength scope is the semiconductor laser of 300nm-800nm.

Utilize said apparatus to carry out a method for Magnetooptic ellipsometry measurement, step is as follows:

1. measurement mechanism is switched on power, give chopper, lock-in amplifier power supply, open the power supply of electromagnet power supply, wavelengthtunable laser instrument and PC;

2. the output wavelength of wavelengthtunable laser instrument is 300nm-800nm, regulates Laser Power Devices within the scope of its output wavelength, to set the laser signal of an initial output wavelength;

3. the film sample material with ferromagnetic property is fixed on sample stage, adjusts sample it is rotated in the horizontal direction, make sample surfaces parallel with magnetic direction;

4. adjust the frequency of chopper, this frequency is inputted lock-in amplifier as reference signal frequency, the output terminal of photodetector is connected to the signal input part of lock-in amplifier;

5. regulate the diaphragm that wavelengthtunable laser instrument places, the position of the polarizer below, then regulate the position of analyzer, condenser, photodetector, make laser normal incidence and can converge on photodetector by above-mentioned optical element;

6. open PC, observe PC and can gather and stored signal data;

7. the optical filter corresponding with input optical maser wavelength installed to detector input end, thereby prevent that parasitic light from entering photodetector;

8. selected polarizer polarizing angle degree is θ ₁, analyzer analyzing angle is θ ₂, lock-in amplifier is connected with photodetector, and what now lock-in amplifier was exported is the photocurrent intensity that photodetector receives, the intensity I of the photocurrent that when PC records Bu Jia magnetic field, lock-in amplifier is measured ₀; Forward regulating magnet electric current I _m, PC record lock-in amplifier registration I now ₊; Oppositely regulating magnet electric current is to-I _m, PC record lock-in amplifier registration I now _-thereby, obtain Δ I/I ₀=(I ₊-I _-)/I ₀, wherein: Δ I=I ₊-I _-, record polarizer polarizing angle θ simultaneously ₁with analyzer inspection bias angle theta ₂;

9. the polarizing angle degree θ that keeps the polarizer ₁constant, rotation analyzer, increases analyzing angle θ ₂, 8., it is 5 ° that wherein analyzing angle increases step-length to repeating step, until be increased to 180 °, thus obtain many group Δ I/I ₀and θ ₁, θ ₂;

10. by the incident angle of laser polarizing angle θ ₁, inspection bias angle theta ₂with the Δ I/I recording ₀in input PC, by PC, calculated magneto-optic coupling coefficient Q and the refractive index N of sample;

regulate Laser Power Devices, within the scope of the output wavelength of wavelengthtunable laser instrument, set a new output wavelength, repetitive process 7.-10., until survey complete spectral range; Obtain the curve of spectrum of magneto-optic coupling coefficient Q and refractive index N.

The principle of Magnetooptic ellipsometry test of the present utility model is as follows:

Magnetooptic ellipsometry test is in the sample surfaces reflex time a kind of test mode that causes polarization state to change affected by magnetic fields based on light.When sample surfaces adds the magnetic field of positive and negative both direction, can cause the difference of reflected light polarization state, thereby cause the difference of the light signal strength that photodetector receives.According to the both forward and reverse directions in magnetic field, the light intensity that photodetector receives is respectively I ₊with I _-.The light intensity receiving when external magnetic field is zero is I ₀, can obtain the rate of change Δ I/I of light intensity ₀=(I ₊-I _-) I ₀.Set three different polarizer angle θ ₁, measure respectively at different analyzer angle θ ₂under light intensity rate of change, thereby obtain light intensity rate of change Δ I/I ₀with θ ₂change curve, light intensity rate of change Δ I/I ₀with θ ₂the formula of change curve foundation as follows:

$\frac{\mathrm{\&Delta;I}}{I_0}=\frac{2B_1({\sin }^2\left({\mathrm{\&theta;}}_1\right)\sin \left(2{\mathrm{\&theta;}}_2\right)-{\sin }^2\left({\mathrm{\&theta;}}_2\right)\sin \left(2{\mathrm{\&theta;}}_1\right))+2B_2({\cos }^2\left({\mathrm{\&theta;}}_2\right)\sin \left(2{\mathrm{\&theta;}}_1\right)-{\cos }^2\left({\mathrm{\&theta;}}_1\right)\sin \left(2{\mathrm{\&theta;}}_2\right))+4{\mathrm{<figure-callout\; id="3"\; label="B"\; filenames="HDA00003422660100011.png"\; state="\{\{state\}\}">B</figure-callout>}}_3{\sin }^2\left({\mathrm{\&theta;}}_1\right){\sin }^2\left({\mathrm{\&theta;}}_2\right)+{\mathrm{<figure-callout\; id="4"\; label="B"\; filenames="HDA00003422660100011.png"\; state="\{\{state\}\}">B</figure-callout>}}_4\sin \left(2{\mathrm{\&theta;}}_1\right)\sin \left(2{\mathrm{\&theta;}}_2\right)}{{\sin }^2\left({\mathrm{\&theta;}}_1\right){\sin }^2\left({\mathrm{\&theta;}}_2\right)+{\mathrm{<figure-callout\; id="5"\; label="B"\; filenames="HDA00003422660100011.png"\; state="\{\{state\}\}">B</figure-callout>}}_5{\cos }^2\left({\mathrm{\&theta;}}_1\right){\cos }^2\left({\mathrm{\&theta;}}_1\right)+2{\mathrm{<figure-callout\; id="6"\; label="B"\; filenames="HDA00003422660100011.png"\; state="\{\{state\}\}">B</figure-callout>}}_6\sin \left({\mathrm{\&theta;}}_1\right)\cos \left({\mathrm{\&theta;}}_1\right)\sin \left({\mathrm{\&theta;}}_2\right)\cos \left({\mathrm{\&theta;}}_2\right)},$

Fit within three different polarizer angle θ simultaneously ₁the light intensity rate of change Δ I/I of lower gained ₀with θ ₂change curve, can obtain the coefficient B in above formula ₁, B ₂, B ₃, B ₄, B ₅, B ₆, by coefficient B ₅, B ₆incident angle with incident ray

bring the birefringence angle that can obtain incident light in following formula into

Wherein: i represents plural imaginary part, e represents the end of natural logarithm.Pass through coefficient B ₁, B ₂, B ₅, B ₆, incident ray incident angle

and the birefringence angle of incident light

all parameters can be obtained magneto-optic coupling coefficient Q and the refractive index N of sample of magnetic material, and concrete solution formula is as follows:

Feature of the present utility model is as follows:

(1), wavelengthtunable laser instrument is higher than the power stability of common white radiant, experimental result is more accurately and can be used for the measurement of magnetic ultra-thin materials.

(2), by regulating the output frequency and corresponding optical filter of laser instrument, can test the spectral measurement of magnetic material magneto-optic coupling coefficient, simple to operate.

(3), light path is simple and practical, optical device required in light path is all general optical device, cost is low.

Accompanying drawing explanation

Fig. 1 is the structural representation of the utility model measurement mechanism.

Wherein: 1, Laser Power Devices, 2, wavelengthtunable laser instrument, 3, the polarizer, 4, diaphragm, 5, sample stage, 6, electromagnet, 7, diaphragm, 8, chopper, 9, analyzer, 10, condenser, 11, optical filter, 12, photodetector, 13, lock-in amplifier, 14, PC.

Embodiment

Below in conjunction with drawings and Examples, the utility model is described further, but is not limited to this.

Embodiment:

The utility model embodiment as shown in Figure 1, a kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test, comprise Laser Power Devices 1, wavelengthtunable laser instrument 2, light path system, electromagnet 6, lock-in amplifier 13 and PC 14, it is characterized in that light path system comprises the polarizer 3, two diaphragms 4 and 7, chopper 8, analyzer 9, condenser 10, optical filter 11 and photodetectors 12, Laser Power Devices 1 are connected with wavelengthtunable laser instrument 2, by regulating the electric current of Laser Power Devices 1 can make the laser of wavelengthtunable laser instrument 2 outgoing different frequencies; Chopper 8 is connected with lock-in amplifier 13; Before wavelengthtunable laser instrument 2 is positioned at the polarizer 3, by the polarizer 3, starts to prolong light path and be sequentially arranged as two diaphragms 4 and 7, chopper 8, analyzer 9, condenser 10, optical filter 11 and photodetector 12; Between two diaphragms 4 and 7, place sample stage 5, sample stage 5 is positioned in the middle of electromagnet 6; The output terminal of photodetector 12 is connected to the input end of lock-in amplifier 13, and the output terminal of lock-in amplifier 13 is connected to PC 14, with observed and recorded computation and measurement result.

Described photodetector 12 is silicon photocell detector, and the mode being installed by trim ring connects preposition optical filter 11.

Described wavelengthtunable laser instrument 2 is that output wavelength scope is the semiconductor laser of 300nm-800nm.

Claims (3)

1. a device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test, comprise Laser Power Devices, wavelengthtunable laser instrument, light path system, electromagnet, lock-in amplifier and PC, it is characterized in that light path system comprises the polarizer, two diaphragms, chopper, analyzer, condenser, optical filter and photodetectors, Laser Power Devices are connected with wavelengthtunable laser instrument, by regulating the electric current of Laser Power Devices can make the laser of laser emitting different frequency; Chopper is connected with lock-in amplifier; Before wavelengthtunable laser instrument is positioned at the polarizer, by the polarizer, starts to prolong light path and be sequentially arranged as two diaphragms, chopper, analyzer, condenser, optical filter and photodetectors; Between two diaphragms, place sample stage, sample stage is positioned in the middle of electromagnet; The output terminal of photodetector is connected to the input end of lock-in amplifier, and the output terminal of lock-in amplifier is connected to PC, with observed and recorded computation and measurement result.

2. a kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test as claimed in claim 1, is characterized in that described photodetector is silicon photocell detector, and the mode being installed by trim ring connects preposition optical filter.

3. a kind of device that utilizes wavelengthtunable laser instrument to carry out Magnetooptic ellipsometry test as claimed in claim 1, is characterized in that described wavelengthtunable laser instrument is that output wavelength scope is the semiconductor laser of 300nm-800nm.

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