CN205406953U - Surplus amplitude modulation stabilising arrangement based on angle of wedge electro -optical crystal - Google Patents
Surplus amplitude modulation stabilising arrangement based on angle of wedge electro -optical crystal Download PDFInfo
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- CN205406953U CN205406953U CN201620195683.5U CN201620195683U CN205406953U CN 205406953 U CN205406953 U CN 205406953U CN 201620195683 U CN201620195683 U CN 201620195683U CN 205406953 U CN205406953 U CN 205406953U
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Abstract
The utility model discloses a surplus amplitude modulation stabilising arrangement based on angle of wedge electro -optical crystal relates to laser frequency stabilization technical field. This device is: laser instrument, the polarizer, electro -optical crystal, analyser and polarization splitting prism arrange in proper order and constitute the light path part, lightning phase modulation part is constituteed to signal source, copper foil, electro -optical crystal, copper billet, thermoelectric cooler and heat sink connecting gradually, signal source, the local side that moves looks ware and first detector connect gradually and obtain the required local oscillating signal of demodulation, the radio -frequency head of polarization splitting prism's vertical polarization light, photoelectric detector and first detector communicates acquisition radiofrequency signal in proper order, acquisition surplus amplitude modulation signal is connected to the intermediate frequency end and the digital multimeter of first detector, electro -optical crystal be a lithium niobate crystal that has the angle of wedge, lead to 75 degrees contained angles on the plain noodles and optical axis direction one -tenth. This device simple structure, stability is high, easily realizes, can be applied to precision measurement fields such as high stable laser, laser Interferometer, gravitational wave observation, laser spectroscopy and optical frequency standard.
Description
Technical field
This utility model relates to laser steady frequency technology field, particularly relates to a kind of residual amplitude modulation stabilising arrangement based on angle of wedge electro-optic crystal.
Background technology
In the research adopting high stable accurate laser measurement and technology application, such as spectroscopy, opctical frequency standard and gravitational wave are observed in this class accurate measurement research, and phase-modulation and photodetection are the most frequently used high sensitivity detecting techniques.And electric light phase-modulation is one of means the most frequently used in phase-modulation.And the change of many physical effects and environmental factors all inevitably produces residual amplitude modulation in electric light phase modulation process, and then the stability measured of impact and accuracy.Such as in FM Spectroscopy Measurement, residual amplitude modulation effect can cause spectrum profile distortion, reduces the sensitivity of spectral measurement；In laser interferometer, the fluctuation of residual amplitude modulation can directly reduce the stability of measurement.
The means reducing residual amplitude modulation are broadly divided into two classes: stablize residual amplitude modulation passively and it is carried out actively control.Passive mode generally can pass through ambient parameter such as temperature, the air pressure etc. stablized residing for electro-optic phase modulator or even whole system, reduces the impact that system light path is pointed to by air-flow, vibration and sound.But the detection for higher sensitivity, the passive mode adopted at present is generally difficult to meet requirement.Then, in order to reduce the residual amplitude modulation impact on certainty of measurement, also can in the mode controlled in combination with active feedback of passive stabilization.But actively control to need extra optics or the electricity component of adding to realize feedback control, this mode will necessarily increase the complexity of whole measurement system, reduces the reliability of system, is not suitable for miniaturized application.
Utility model content
The purpose of this utility model is that the shortcoming and defect overcoming prior art to exist, it is provided that a kind of residual amplitude modulation stabilising arrangement based on angle of wedge electro-optic crystal.Require effectively to suppress residual amplitude modulation, and simple in construction, be easily achieved, the impact of environmental factors is also insensitive.
The purpose of this utility model is achieved in that
Logical bright finish is adopted to have the electro-optic crystal of the angle of wedge, by the residual amplitude modulation produced in electro-optic crystal temperature control passively stable phase angle modulated process；Horizontal polarization light (o light) that crystal birefringence can be produced by this electro-optic crystal having an angle of wedge and orthogonal polarized light (e light) are from spatially separating, thus the residual amplitude modulation that significantly abatement birefringence introduces, and owing to former and later two logical bright finish of electro-optic crystal are made that the bigger angle of wedge, can being prevented effectively from the parasitic etalon effect that electro-optic crystal self introduces, this parasitic etalon effect is also one of main source of residual amplitude modulation.
Specifically, the structure of this device is:
Laser instrument, the polarizer, electro-optic crystal, analyzer and polarization splitting prism are arranged in order composition light path part；
Signal source, Copper Foil, electro-optic crystal, copper billet, thermoelectric module and heat sink being sequentially connected with form electric light phase-modulation part；
The local side of signal source, phase shifter and frequency mixer is sequentially connected with and obtains the local oscillated signal that demodulation is required；
The radio-frequency head of the orthogonal polarized light of polarization splitting prism, photodetector and frequency mixer is sequentially communicated acquisition radiofrequency signal；
The intermediate frequency end of frequency mixer and digital multimeter connect acquisition residual amplitude modulation signal；
Described electro-optic crystal is a kind of lithium columbate crystal having the angle of wedge, and logical bright finish becomes 75 degree of angles with optical axis direction.
This utility model has the advantages that:
1. simple in construction, easily realizes the processing request of electro-optic crystal；
2. need not additionally increasing feedback control loop, Circuits System is simple；
3. two pieces of reflecting mirrors are utilized not change relative to the direction of incident illumination by the direction of emergent light so that light path becomes compact；
4. former and later two logical bright finish of electro-optic crystal are made that the bigger angle of wedge so that the angle spatially separated from the o light of electric light outgoing and e light is bigger；
5. this design having the angle of wedge of electro-optic crystal, it is possible to be prevented effectively from the parasitic etalon effect that electro-optic crystal self introduces；
6. this device and operation principle thereof have general applicability, can be used for other type of electro-optic phase modulator.
In a word, this apparatus structure is simple, and stability is high, it is easy to accomplish, can be applicable to the field of precision measurement such as high stable laser, laser interference, gravitational wave observation, laser spectroscopy and opctical frequency standard.
Accompanying drawing explanation
Fig. 1 is the block diagram of this device,
In figure:
00 light source and light path,
01 laser instrument, 02 polarizer, 03 analyzer, 04 polarization splitting prism；
10 electric light phase modulation module,
11 Copper Foils, 12 electro-optic crystals, 13 copper billets, 14 thermoelectric modules,
15 is heat sink, 16 signal sources；
20 detecting modules,
21 photodetectors, 22 frequency mixers, 23 phase shifters, 24 digital multimeter.
Fig. 2 is the top view of electro-optic crystal and folding light path schematic diagram,
Figure gives light is oblique is mapped to the track after electro-optic crystal；
Fig. 3 is the logarithmic plot (representing with Allan deviation) of residual amplitude modulation degree of stability in 90 degree of phase demodulating situations；
Abscissa: average time (second), vertical coordinate: residual amplitude modulation degree of stability；
Curve 1: do not have electro-optic crystal degree of stability of residual amplitude modulation under light normal incidence of the angle of wedge,
Curve 2: do not have the electro-optic crystal of the angle of wedge in light vertical incidence and actively to control to open residue in situation
The degree of stability of amplitude modulation(PAM),
Curve 3: have the electro-optic crystal of the angle of wedge in light oblique incidence and only to detect the degree of stability of residual amplitude modulation in e light situation,
Curve 4: do not have the Noise Background of device in light situation.
Detailed description of the invention
Below in conjunction with drawings and Examples, this device is described in detail:
One, the structure of device
1, overall
Such as Fig. 1, this device includes light source and light path 00, electric light phase modulation module 10 and detecting module 20；
Light source and light path 00 include laser instrument 01, the polarizer 02, analyzer 03 and polarization splitting prism 04；
Electric light phase modulation module 10 include Copper Foil 11, electro-optic crystal 12, copper billet 13, thermoelectric module 14, heat sink 15 and signal source 16；
Detecting module 20 includes photodetector 21, frequency mixer 22, phase shifter 23 and digital multimeter 24；
Its position and annexation be:
Laser instrument 01, the polarizer 02, electro-optic crystal 12, analyzer 03 and polarization splitting prism 04 are arranged in order composition light path part；
Signal source 16, Copper Foil 11, electro-optic crystal 12, copper billet 13, thermoelectric module 14 and heat sink 15 are sequentially connected with composition electric light phase-modulation part, and (electro-optic crystal 12 Wear Characteristics of Epoxy Adhesive is on copper billet 13, copper billet 13, thermoelectric module 14 and heat sink 15 stack gradually placement, copper billet 13 and thermoelectric module 14, thermoelectric module 14 and heat sink between gap use heat-conducting silicone grease to fill)；
The local side of signal source 16, phase shifter 23 and frequency mixer 22 is sequentially connected with and obtains the local oscillated signal that demodulation is required；
The radio-frequency head of the orthogonal polarized light of polarization splitting prism 04, photodetector 21 and frequency mixer 22 is sequentially communicated acquisition radiofrequency signal；
The intermediate frequency end of frequency mixer 22 and digital multimeter 24 connect acquisition residual amplitude modulation signal.
2, functional part
0) light source and light path 00
(1) laser instrument 01
Laser instrument 01 is a kind of general-purpose device, such as Nd-YAG laser instrument.
(2) polarizer 02
The polarizer 02 is a kind of Glan-Taylor prism, and for filtering the polarization state through light beam, making to pass through light beam is line polarized light, and passing through the polarization direction of light beam in this device with the main shaft angle of electro-optic crystal 12 is 2～3 °.
(3) analyzer 03
Analyzer 03 is identical structure with the polarizer 02, is the optics of inspection polarized light.
(4) polarization splitting prism 04
Polarization splitting prism 04 is a kind of general-purpose device, is made up of two pieces of corner cube prisms；Incident non-polarized light is divided into two bundles be mutually perpendicular to and highly purified line polarized light.
1) electric light phase modulation module 10
(1) Copper Foil 11, electro-optic crystal 12 and copper billet 13
Copper Foil 11, electro-optic crystal 12 and copper billet 13 are sequentially connected with composition electro-optic phase modulator.
Described electro-optic crystal 12 is a kind of lithium columbate crystal having the angle of wedge, and logical bright finish becomes 75 degree of angles with optical axis direction；
Crystalline size is: length × wide × height=32mm × 5mm × 3mm, cuts along optical axis direction, and logical bright finish becomes 75 degree of angles with optical axis direction, the light field passed through can be carried out phase-modulation after it is driven by signal source 16.
(2) thermoelectric module 14
Thermoelectric module 14 is a kind of general TEC.
(3) heat sink 15
Heat sink 15 is a kind of aluminium block, as the constant temperature thermal source of temperature control, reduces temperature fluctuation.
(4) signal source 16
Signal source 16 selects radio-frequency signal generator.
2) detecting module 20
(1) photodetector 21
Photodetector 21 is general photoelectric switching circuit, and its responsive bandwidth is more than the frequency of phase-modulation.
(2) frequency mixer 22
Frequency mixer 22 is a kind of general passive frequency mixer, and as selected SRA-1-1, local port input power is 0dBm, and voltage conversion coefficient is 0.8.
(3) phase shifter 23
Phase shifter 23 is a kind of general active phase-shift circuit, and postponing phase place can adjust between spending at 0 degree-180 continuously.
(4) digital multimeter 24
Digital multimeter 24 is a kind of general instrument measuring voltage.
3, operation principle
1) light path part
Such as Fig. 1, the beam of laser (A) that light path part is sent by laser instrument 01 enters electro-optic crystal 12 by (B) after the polarizer 02, signal source 16 drives electro-optic crystal 12 and the light field passed through is carried out phase-modulation, then the light after modulation is divided into two-way through analyzer 03 and polarization splitting prism 04 by light beam (e), through light (C) for adopting the Photoelectric Detection of phase-modulation to apply, reflection light (D) is for the detection of residual amplitude modulation.
Such as Fig. 2, the light propagated in electro-optic crystal 12 has two orthogonal polarization states, is called o light and e light, and the interference between this two-way light is the main cause producing residual amplitude modulation；And the logical bright finish adopted here has the electro-optic crystal 12 of the angle of wedge so that o light and e light are spatially separated, it is to avoid interaction therebetween, the residual amplitude modulation that birefringence effect can be caused is preferably minimized.
2, residual amplitude modulation probe portion
Residual amplitude modulation probe portion is the reflection light (D) utilizing photodetector 21 detecting polarization Amici prism 04 out, convert optical signal into the signal of telecommunication and the radio-frequency head with frequency mixer 22 is connected, it is demodulated by recycling frequency mixer 22, and the local oscillations wherein demodulated is provided by the signal source 16 signal after phase shifter 23 phase shift；The output of ultimately mixing device 22 intermediate frequency end is for detecting the signal of residual amplitude modulation.
Two, the result that actual measurement is obtained is as follows:
After Fig. 3 shows use scheme of the present utility model, there is the degree of stability of the electro-optic crystal residual amplitude modulation of the angle of wedge, also compared for and do not have angle of wedge electro-optic crystal actively to control front and back and the degree of stability of the residual amplitude modulation having angle of wedge electro-optic crystal.
Each curve from following:
The residual amplitude modulation degree of stability of curve 2 is better than the residual amplitude modulation degree of stability of curve 1；
The residual amplitude modulation degree of stability of curve 3 is better than the residual amplitude modulation degree of stability of curve 2；
The residual amplitude modulation degree of stability of curve 3 is already close to the residual amplitude modulation degree of stability of curve 4.
In the scope of 1s～1000s average time, the crystal residual amplitude modulation degree of stability having the angle of wedge is higher than not having the degree of stability that angle of wedge crystal actively controls to open in situation, especially, in the scope of 1s～50s average time, there is the crystal residual amplitude modulation degree of stability of the angle of wedge already close to there is no the Noise Background of device in light situation.
Claims (1)
1. the residual amplitude modulation stabilising arrangement based on angle of wedge electro-optic crystal, it is characterised in that:
Laser instrument (01), the polarizer (02), electro-optic crystal (12), analyzer (03) and polarization splitting prism (04) are arranged in order composition light path part；
Signal source (16), Copper Foil (11), electro-optic crystal (12), copper billet (13), thermoelectric module (14) and heat sink (15) are sequentially connected with composition electric light phase-modulation part；
The local side of signal source (16), phase shifter (23) and frequency mixer (22) is sequentially connected with and obtains the local oscillated signal that demodulation is required；
The radio-frequency head of the orthogonal polarized light of polarization splitting prism (04), photodetector (21) and frequency mixer (22) is sequentially communicated acquisition radiofrequency signal；
The intermediate frequency end of frequency mixer (22) and digital multimeter (24) connect acquisition residual amplitude modulation signal；
Described electro-optic crystal (12) is a kind of lithium columbate crystal having the angle of wedge, and logical bright finish becomes 75 degree of angles with optical axis direction.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620195683.5U CN205406953U (en) | 2016-03-14 | 2016-03-14 | Surplus amplitude modulation stabilising arrangement based on angle of wedge electro -optical crystal |
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| CN201620195683.5U CN205406953U (en) | 2016-03-14 | 2016-03-14 | Surplus amplitude modulation stabilising arrangement based on angle of wedge electro -optical crystal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105576495A (en) * | 2016-03-14 | 2016-05-11 | 中国科学院武汉物理与数学研究所 | Residual amplitude modulation stabilization device based on wedge angle electro-optic crystal |
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2016
- 2016-03-14 CN CN201620195683.5U patent/CN205406953U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105576495A (en) * | 2016-03-14 | 2016-05-11 | 中国科学院武汉物理与数学研究所 | Residual amplitude modulation stabilization device based on wedge angle electro-optic crystal |
| CN105576495B (en) * | 2016-03-14 | 2019-01-29 | 中国科学院武汉物理与数学研究所 | Residual amplitude modulation stabilising arrangement based on angle of wedge electro-optic crystal |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20160727 Effective date of abandoning: 20190129 |
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| AV01 | Patent right actively abandoned |
Granted publication date: 20160727 Effective date of abandoning: 20190129 |
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| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |