CN103825184B - A kind of ultra-narrow band excited state faraday anomalous dispersion atomic light filter of communication band - Google Patents
A kind of ultra-narrow band excited state faraday anomalous dispersion atomic light filter of communication band Download PDFInfo
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Abstract
The invention belongs to Space Optical Communication Technologies field, be specifically related to the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of a kind of communication band.For being effectively improved the pumping efficiency of excited atom light filter, and overcome the light path complexity because pumping laser frequency stabilization module causes, environmental condition to require the problem that height, bad adaptability and practicality are low, this light filter eliminates external frequency stabilization module, but utilize the Rb atom vapor absworption peak within light filter as frequency standard, structure is simpler, job stability is more preferable and in hgher efficiency, owing to the program combines the generation principle of many transition absorption band, use and there is frequency stabilization mode targetedly very much such that it is able to obtain good pumping effect.
Description
Technical field
The invention belongs to Space Optical Communication Technologies field, be specifically related to the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of a kind of communication band.
Background technology
The effect of light filter is to extract faint narrowband optical signal from stronger wide band background light, and it is one of key device in the various application technologies such as submarine optical communication, FSO, deep space optical communication, remote sensing, laser radar, meteorology.In order to effectively suppress the background noise such as solar radiation, black body radiation and the scattered light caused by the scattering medium such as air, sea water and benthic luminescence, ensure that reception system has higher signal to noise ratio, flashlight can be efficiently transmitted again simultaneously, reception system is made to have higher detection sensitivity, require that light filter has a following performance: narrow bandwidth, high-transmission rate, the big angle of visual field and higher out-of-band noise rejection ratio, simultaneously in order to meet the needs of Real-Time Optical communication, it is desirable to system has degree time response faster.
Traditional light filter such as interferometric filter, its passband width is in the magnitude of 10nm；Utilizing some crystal filter that birefringence effect is made, its optical filtering bandwidth is inversely proportional to the thickness of crystal, and the thickness increasing crystal can be substantially reduced its reception solid angle the loss increasing in passband, it is difficult to meet the requirement of narrow bandwidth and high-transmission rate simultaneously.In a word, the performance of conventional filters can not meet far away the requirement of current practice.
From eighties of last century seventies, people start to consider to utilize the ultra-narrow band resonance characteristics of atom to develop filtering device, and ARF (atom resonance filter, atom resonance light filter) is one of them.Through the research in more than ten years, all have been reported that for laser radar, subsurface communication, ARF to purposes such as latent communication, atmospheric communication, deep space communications.But being as the development of ARF, people are the most gradually found that the limitation of ARF, such as low-response, it is impossible to for imaging etc..
In 1991, a kind of novel atomic light filter: Faraday anomalous dispersion optical filter (Faraday anomalous dispersion optical filter, FADOF) is developed.Faraday anomalous dispersion phenomenon refers to when line polarized light is propagated in the atom vapor added with constant longitudinal magnetic field, owing to Atomic Absorption line issues estranged splitting at the action of a magnetic field, there are different absorptions and effect of dispersion for Left-hand circular polarization (LCP) light and right-hand circular polarization (RCP) light, cause former line polarized light plane of polarization to rotate.
FADOF is made up of two orthogonal polaroids and the atom steam chest being placed in longitudinal magnetic field, first polaroid is used for being polarized, the Resonant Faraday effect of atom vapor makes the plane of polarization of the flashlight in passband rotate, by the change of temperature and magnetic field being controlled the angle rotated, enable the flashlight in passband to greatest extent through second polaroid for analyzing, and out of band signal plane of polarization is constant, then blocked by the Glan prism that two panels is orthogonal.This is the ultimate principle that FADOF filters.
The service band of FADOF is limited to the Absorption Line of atom, and its transmission peaks position is normally in the passband width of the several GHz in Atomic Absorption line center, is mainly determined by the broadening effect of Atomic Absorption line, such as dopplerbroadening, collision broadening etc..In order to make the atomic light filter of wave band needed for certain, it is necessary to find the Atomic Absorption line in this target wave band.Owing to the Basic Physical Properties of material limits, mainly alkali metal atom and the part alkaline earth metal atom of atomic light filter can be made at present, because the steam of these atoms can obtain at relatively low temperature.The limitednumber of atom, the ground state absorption line of these atoms covers wave band also cannot well meet various needs.But it is the most much broader that the excited state transition of atom covers wave band, and therefore the atomic light filter of excited state becomes research emphasis later.
The difficult point of excited atom light filter is how to prepare the atom population of excited state, because under normal condition, atom is in the ground state level of minimum energy, if wanting to utilize excited of atoms to make light filter, is necessary for, by external energy, atom is activated to excited state up from ground state.This process can use the extrinsic motivated sources such as laser pump (ing), atomic lamp pump or microwave excitation to realize.Wherein, laser is the highest as driving source efficiency, and accuracy is best, and many atoms that makes of can trying one's best are on target excited level.And atomic lamp or microwave excitation are more uncontrollable, it is all to be dropped at random to low-lying level by atom after in atomic excitation to some high level, atom can be caused to have population at multiple energy levels, although transmission spectral line can also be obtained, but which excitation level uncontrollable atom is in, also can produce the fluorescence interference signal of the non-constant width of bands of a spectrum simultaneously.
Laser pump (ing) also with the presence of its shortcoming, i.e. laser as one accurately pump mode, its optical maser wavelength must be exactly aligned the ground state level transition of atom, this just frequency stability to laser propose higher requirement.Therefore the excited atom light filter using laser pump (ing) must comprise pumping laser frequency stabilization module.Currently used laser frequency stabilization module has atom saturated absorption spectrum frequency stabilization and the big class of optical resonator frequency stabilization two, and it has in common that light path is more complicated, and requires higher to working environment, and bad adaptability, the practicality causing excited atom light filter is relatively low.Therefore, how for these defects, it is provided that a kind of pumping efficiency being effectively improved excited atom light filter simplifies the excited state faraday anomalous dispersion atomic light filter of laser frequency stabilization module simultaneously, it has also become the technique direction of primary study at present.
Summary of the invention
(1) to solve the technical problem that
The technical problem to be solved in the present invention is: for existing excited state faraday anomalous dispersion atomic light filter, how to be effectively improved the pumping efficiency of excited atom light filter, and overcome the light path complexity because pumping laser frequency stabilization module causes, environmental condition to require the problem that height, bad adaptability and practicality are low.
(2) technical scheme
For solving above-mentioned technical problem, the present invention provides the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of a kind of communication band, and described light filter includes: semiconductor laser 1, laser isolator 2, coupling dichroism eyeglass 3, light splitting dichroism eyeglass 4, Rb atom steam bubble 5, magnetic field generator 6, heater 7, analyzer 8, polarizer 9, the quarter-wave plate 10 of 780nm, polarization splitting prism the 11, first photodetector the 12, second photodetector 13, difference engine 14 and frequency stabilization servomechanism 15；
Described semiconductor laser 1 is tunable 780nm semiconductor laser, and it is used for providing Rb atomic ground state 52S1/2To target excited state 52P3/2Pumping laser；
Described laser isolator 2 is used for guaranteeing that pumping laser signal is unidirectional and passes through, and cuts off by the optical signal reflected on rear class optics；
Described coupling dichroism eyeglass 3 is arranged between described analyzer 8 and Rb atom steam bubble 5, and be positioned on the transmitted light path of described laser isolator 2, it is set to 1529nm light highly transmissive, and 780nm light height is reflected, it is for reducing the loss of flashlight as far as possible while pumping laser is introduced light filter light path；
Described light splitting dichroism eyeglass 4 is arranged between described Rb atom steam bubble 5 and polarizer 9, and be positioned on the transmitted light path of described Rb atom steam bubble 5, it is set to 1529nm light highly transmissive, 780nm light height is reflected, it is for extracting pump light from light filter light path, in case carrying out frequency stabilization in rear class light path, reduce the loss of flashlight as far as possible simultaneously；
Described Rb atom steam bubble 5 is arranged on described coupling dichroism eyeglass 3 reflected light path, and bubble uses quartz material, and it is set to all possess high-transmission rate at near-infrared 780nm and 1529nm；
Described magnetic field generator 6 is arranged on described Rb atom steam bubble 5, and it is for producing the external magnetic field signal for acting on Rb atom steam bubble 5；
Described heater 7 is arranged on described Rb atom steam bubble 5, and it is for controlling the operating temperature of described Rb atom steam bubble 5；
Described analyzer 8 and polarizer 9 are arranged at the light path two ends of described Rb atom steam bubble 5, described analyzer 8 is set to mutually orthogonal with polarizer 9, the flashlight that described polarizer 9 is positioned to allow for linear polarization passes through, and makes veiling glare only have a linear polarization component to pass through；Described analyzer 8 is set to by the spurious rays polarized component that filter out through polarizer 9 pass through mutually orthogonal with polarizer 9；
The quarter-wave plate 10 of described 780nm, it is arranged on the reflected light path of described light splitting dichroism eyeglass 4, and it is for becoming the line polarized light on wave plate main shaft and the angled direction of countershaft respectively by Left-hand circular polarization component and the right-hand circular polarization component of incident optical signal；
Described polarization splitting prism 11 is arranged on the exit path of described quarter-wave plate 10, it is for by the line polarized light beam splitting on the main shaft of quarter-wave plate 10 outgoing and countershaft direction, outgoing in the two directions, thus left circularly polarized light and the right-hand circular polarization light component of optical signal are extracted respectively；
Described first photodetector 12 is for will be converted into first signal of telecommunication the aforementioned left circularly polarized light extracted and export to difference engine 14；
Described second photodetector 13 is for will be converted into second signal of telecommunication the aforementioned right-circularly polarized light extracted and export to difference engine 14；
Described difference engine 14, for first signal of telecommunication of input and second signal of telecommunication are carried out signal subtraction, generates frequency offset signals；
Described frequency stabilization servomechanism 15 is for according to described frequency offset signals, generate the control signal feeding back to described semiconductor laser 1, described control signal is for adjusting the operating frequency of semiconductor laser 1, and frequency of amendment offsets, thus optical maser wavelength is locked on the position that pumping efficiency is maximum.
Wherein, in the light path of described Rb atom steam bubble 5, the other end of the described relative Rb atom steam bubble 5 of polarizer 9 is additionally provided with tunable 1529nm lasing light emitter 16, and the other end of the described relative Rb atom steam bubble 5 of analyzer 8 is additionally provided with the 3rd photodetector 17；
Described tunable 1529nm lasing light emitter 16 is used for producing wavelength continually varying flashlight and is incident to Rb atom steam bubble 5 through polarizer 9, thus for the transmission case of one section of continuous wavelength range signals light of detection；
Described 3rd photodetector 17 is for being converted into signal of telecommunication record by the flashlight of analyzer 8 transmission, wavelength consecutive variations because of flashlight, the flashlight recording transmission the most continuously can be obtained by with wavelength as independent variable, and absorbance is the curve of value, namely transmission spectrum.
Wherein, the light splitting axle angle at 45 ° of the main shaft of described quarter-wave plate 10 and countershaft and described polarization splitting prism 11.
Wherein, described heater 7 is operated in the arbitrary temp of room temperature to 200 DEG C for controlling described Rb atom steam bubble 5.
(3) beneficial effect
Compared with prior art, technical solution of the present invention possesses some beneficial effect following:
(1) pumping efficiency is high, and pumping degree of accuracy and final light filter parameter are above microwave excitation or atomic lamp pump.
(2) simple in construction, eliminates outside frequency regulator, uses atomic light filter interior atoms vaporium to carry out frequency stabilization, reduces the requirement of environment to external world.
(3) long-time stability are preferable, use the mangneto division zone frequency stabilization of atom, can follow magnetic field slight change Automatic adjusument operation wavelength to a certain extent, remain efficient pumping.
Accompanying drawing explanation
The atomic transition line schematic diagram that Fig. 1 is utilized by communication band Rb atomic light filter.
Fig. 2 is the Rb atomic ground state energy many absorption bands phenomenon schematic diagram to first excited state energy level.
Fig. 3 is the spectral line schematic diagram that Simple Theory model produces mangneto many transition line coincidence phenomenon.
Fig. 4 is the circular polarization differential signal schematic diagram that Simple Theory model obtains.
Fig. 5 is the spectral line schematic diagram of mangneto many transition line coincidence phenomenon that the actual measurement of Rb atom D2 line obtains.
Fig. 6 is that the circular polarization differential signal schematic diagram obtained surveyed by Rb atom D2 line.
Fig. 7 is the excited state faraday anomalous dispersion atomic light filter overall structure schematic diagram of technical solution of the present invention.
Fig. 8 be 110 DEG C, under the conditions of pumping light power 24mW technical solution of the present invention at the transmission spectral line schematic diagram of 1529nm.
Fig. 9 is at 110 DEG C, the maximum transmission rate situation of change schematic diagram that obtains of different pumping power.
Detailed description of the invention
For making the purpose of the present invention, content and advantage clearer, below in conjunction with the accompanying drawings and embodiment, the detailed description of the invention of the present invention is described in further detail.
First, about the accompanying drawing of the present invention, the atomic transition line schematic diagram that Fig. 1 is utilized by communication band Rb atomic light filter.Fig. 2 is the Rb atomic ground state energy many absorption bands phenomenon schematic diagram to first excited state energy level.Fig. 3 is the spectral line schematic diagram that Simple Theory model produces mangneto many transition line coincidence phenomenon.Fig. 4 is the circular polarization differential signal schematic diagram that Simple Theory model obtains.Fig. 5 is the spectral line schematic diagram of mangneto many transition line coincidence phenomenon that the actual measurement of Rb atom D2 line obtains.Fig. 6 is that the circular polarization differential signal schematic diagram obtained surveyed by Rb atom D2 line.
For solving problem of the prior art, technical solution of the present invention emphasis is for the modal 1.5 mu m waveband laser signals of communication band, choose Alkali Metal Rb atom (rubidium, Rb) as work atom, use working condition and the mode of operation of internal frequency stabilization that many transition overlap, use laser 5 to Rb2S1/2→52P3/2(780.24nm) carry out pumping, then utilize the 5 of Rb2P3/2→42D5/2(1529.354nm) transition makes communication band excited state faraday anomalous dispersion atomic light filter.
Atom has absorption effect for the laser resonated with transition line, but the Absorption Line of the atom of reality is not discrete line distribution, but there is the absorption band distribution of certain bandwidth, and be positioned at absorption band, specifically being at absorption band peak or sideband position, absorbance also and differs.The width of absorption band is mainly determined by broadening, generally comprises natural width, Doppler broadening and pressure collision broadening.In order to obtain as far as possible many atom vapors, the operating temperature of atomic light filter is typically more than 100 degrees Celsius, and broadening effect now is mainly Doppler broadening, and broadening magnitude is about GHz.Additionally, due to the existence of alkali metal atom nuclear spin, there is hyperfine structure in atomic energy level, and for the Rb atom that the present invention uses, its two kinds of isotope 85Rb and 87Rb ground state hyperfine splitting are at a distance of respectively 3GHz and 6.8GHz, excited state 52P3/2Hyperfine splitting narrow, not less than 1GHz, therefore under conditions of not having externally-applied magnetic field, Rb atom all can present the absorption band of four dopplerbroadenings.But typically the most narrower at MHz for the line width of semiconductor laser of laser pump (ing), a Frequency point in an absorption band can only be selected to carry out pumping, be positioned at the atom on other fine-structure levels and then cannot be utilized.Additionally, the atom of faraday anomalous dispersion atomic light filter also needs to be operated in magnetic field, the atom that externally-applied magnetic field can cause magnetic spin quantum number different produces energy level splitting, and absorption band can become wider, more disperse.However, it is possible to by arranging suitable working condition, make the mangneto divisural line overlap of atom difference energy level and merge.Measured by Theoretical Calculation and experiment, select magnetic field to be operated between 450G to 600G, now the 5 of Rb atom2S1/2(F=2)→52P3/2The low frequency wonder division zone of transition band and 52S1/2(F=3)→52P3/2The high frequency drift division zone of transition overlaps, it might even be possible to formed than Absorption Line higher before mangneto division.It is obvious that this enhancement effect is to have merged ratio just to be formed without transition line more strong under magnetic field condition.Select its absorption peak position to carry out pumping under conditions of this many transition line overlaps and can obtain the highest pumping efficiency.
Owing to external magnetic field is relatively strong, Rb atom is 52S1/2→52P3/2Absorption line on line changes the most greatly, and in this case, the laser frequency that external saturated absorption frequency stabilization mode locks is the most no longer the maximum resonance absorption point of light filter core Rb atom；Although and laser frequency can be directed at absorption maximum by the frequency stabilization mode of external optical resonator, but optical resonator is the most sensitive, being affected greatly by working environment, mode of operation easily produces change, and long-time stability are poor.Technical solution of the present invention eliminates external frequency stabilization module, but utilizes the Rb atom vapor absworption peak within light filter as frequency standard, and structure is simpler, and job stability is more preferable and in hgher efficiency.In conjunction with the generation principle of many transition absorption band, the program uses one to have very much frequency stabilization mode targetedly, it is possible to obtain good pumping effect.Because absorption band used by pumping is produced by mangneto division, and it is to be staggered to form by two transition band respective high frequencies drift two absorption bands contrary with low frequency wonder, it is possible to infer that the circular polarization of the two absorption band is the most contrary.Using a simple circular polarization beam splitting light path just can be extracted respectively by the two component, can be absorbed by the way of doing Differential Detection the frequency offset signals in band, and carries out frequency stabilization.
Specifically, as it is shown in fig. 7, Fig. 7 is the main structure chart of technical solution of the present invention.Wherein, the light filter that this technical scheme is provided includes:
Semiconductor laser 1, laser isolator 2, coupling dichroism eyeglass 3, light splitting dichroism eyeglass 4, Rb atom steam bubble 5, magnetic field generator 6, heater 7, analyzer 8, polarizer 9, the quarter-wave plate 10 of 780nm, polarization splitting prism the 11, first photodetector the 12, second photodetector 13, difference engine 14 and frequency stabilization servomechanism 15；
Described semiconductor laser 1 is tunable 780nm semiconductor laser, and it is used for providing Rb atomic ground state 52S1/2To target excited state 52P3/2Pumping laser；
Described laser isolator 2 is used for guaranteeing that pumping laser signal is unidirectional and passes through, and cuts off by the optical signal reflected on rear class optics, to avoid the mode of operation of light feedback influence semiconductor laser, causes job insecurity；
Described coupling dichroism eyeglass 3 is arranged between described analyzer 8 and Rb atom steam bubble 5, and be positioned on the transmitted light path of described laser isolator 2, it is set to 1529nm light highly transmissive, and 780nm light height is reflected, it is for reducing the loss of flashlight as far as possible while pumping laser is introduced light filter light path；
Described light splitting dichroism eyeglass 4 is arranged between described Rb atom steam bubble 5 and polarizer 9, and be positioned on the transmitted light path of described Rb atom steam bubble 5, it is set to 1529nm light highly transmissive, 780nm light height is reflected, it is for extracting pump light from light filter light path, in case carrying out frequency stabilization in rear class light path, reduce the loss of flashlight as far as possible simultaneously；
Described Rb atom steam bubble 5 is arranged on described coupling dichroism eyeglass 3 reflected light path, and bubble uses quartz material, and it is set to all possess high-transmission rate at near-infrared 780nm and 1529nm；The Rb atom steam bubble being placed in magnetic field can make the optical signal polarization direction near resonance level deflect due to faraday anomalous dispersion effect；
Described magnetic field generator 6 is arranged on described Rb atom steam bubble 5, it is for producing the external magnetic field signal for acting on Rb atom steam bubble 5, best in order to reach transition line degrees of fusion, to ensure that magnetic field is evenly distributed in whole light path as far as possible, otherwise the absworption peak wavelength location at same transition line different spatial in the optical path is the most different, it is difficult to realize efficient absorption；
Described heater 7 is arranged on described Rb atom steam bubble 5, and it is for controlling the operating temperature of described Rb atom steam bubble 5；High temperature can improve the saturated vapor pressure in Rb bubble, thus increases gaseous atom number；
Described analyzer 8 and polarizer 9 are arranged at the light path two ends of described Rb atom steam bubble 5, described analyzer 8 is set to mutually orthogonal with polarizer 9, the flashlight that described polarizer 9 is positioned to allow for linear polarization passes through, and makes veiling glare only have a linear polarization component to pass through；Described analyzer 8 is set to by the spurious rays polarized component that filter out through polarizer 9 pass through mutually orthogonal with polarizer 9；
The quarter-wave plate 10 of described 780nm, it is arranged on the reflected light path of described light splitting dichroism eyeglass 4, Left-hand circular polarization component and the right-hand circular polarization component of incident optical signal, for the peculiar property according to quarter-wave plate, are become the line polarized light on wave plate main shaft and the angled direction of countershaft by respectively；
Described polarization splitting prism 11 is arranged on the exit path of described quarter-wave plate 10, it is for by the line polarized light beam splitting on the main shaft of quarter-wave plate 10 outgoing and countershaft direction, outgoing in the two directions, thus left circularly polarized light and the right-hand circular polarization light component of optical signal are extracted respectively；
Described first photodetector 12 is for will be converted into first signal of telecommunication the aforementioned left circularly polarized light extracted and export to difference engine 14；
Described second photodetector 13 is for will be converted into second signal of telecommunication the aforementioned right-circularly polarized light extracted and export to difference engine 14；
Described difference engine 14, for first signal of telecommunication of input and second signal of telecommunication are carried out signal subtraction, generates frequency offset signals；
Described frequency stabilization servomechanism 15 is for according to described frequency offset signals, after amplifying after filtering, generate the control signal feeding back to described semiconductor laser 1, described control signal is for adjusting the operating frequency of semiconductor laser 1, frequency of amendment offsets, thus optical maser wavelength is locked on the position that pumping efficiency is maximum.
Wherein, in the light path of described Rb atom steam bubble 5, the other end of the described relative Rb atom steam bubble 5 of polarizer 9 is additionally provided with tunable 1529nm lasing light emitter 16, and the other end of the described relative Rb atom steam bubble 5 of analyzer 8 is additionally provided with the 3rd photodetector 17；
Described tunable 1529nm lasing light emitter 16 is used for producing wavelength continually varying flashlight and is incident to Rb atom steam bubble 5 through polarizer 9, thus for the transmission case of one section of continuous wavelength range signals light of detection；
Described 3rd photodetector 17 is for being converted into signal of telecommunication record by the flashlight of analyzer 8 transmission, wavelength consecutive variations because of flashlight, the flashlight recording transmission the most continuously can be obtained by with wavelength as independent variable, and absorbance is the curve of value, namely transmission spectrum.
Wherein, the light splitting axle angle at 45 ° of the main shaft of described quarter-wave plate 10 and countershaft and described polarization splitting prism 11.
Wherein, described heater 7 is operated in the arbitrary temp of room temperature to 200 DEG C for controlling described Rb atom steam bubble 5.
For thus, the filtering method implemented based on above-mentioned ultra-narrow band excited state faraday anomalous dispersion atomic light filter specifically can comprise the steps:
Step S1: magnetic field generator 6 produces the external magnetic field signal for acting on Rb atom steam bubble 5；Heater 7 controls the operating temperature of described Rb atom steam bubble 5；Until field signal and temperature meet the predetermined work requirement of Rb atom steam bubble 5；
Step S2: semiconductor laser 1 produces 780nm pumping laser；
Step S3: laser isolator 2 guarantees that pumping laser signal is unidirectional and passes through, cuts off by the optical signal reflected on rear class optics；
Step S4: 780nm pumping laser is reflected by coupling dichroism eyeglass 3, reflection light enters Rb atom steam bubble 5；
Rb atom vapor in step S5:Rb atom steam bubble 5 under the effect of 780nm pumping laser from ground state 52S1/2Excite；
Step S6: the 780nm pumping laser transmitted through Rb atom steam bubble 5 is reflected by light splitting dichroism eyeglass 4, reflection light enters quarter-wave plate 10；
Step S7: Left-hand circular polarization component and the right-hand circular polarization component of incident optical signal are become the line polarized light on wave plate main shaft and the angled direction of countershaft by quarter-wave plate 10 respectively；
Step S8: polarization splitting prism 11 is by the line polarized light beam splitting on the main shaft of quarter-wave plate 10 outgoing and countershaft direction, outgoing in the two directions, thus left circularly polarized light and the right-hand circular polarization light component of optical signal is extracted respectively；
Step S9: the first photodetector 12 will be converted into first signal of telecommunication the aforementioned left circularly polarized light extracted and exports to difference engine 14；Second photodetector 13 is for will be converted into second signal of telecommunication the aforementioned right-circularly polarized light extracted and export to difference engine 14；First signal of telecommunication and second signal of telecommunication of input are carried out signal subtraction by difference engine 14, generate frequency offset signals；
Step S10: frequency stabilization servomechanism 15 is according to described frequency offset signals, by pumping laser Rb to be made atom from ground state 52S1/2It is energized into target excited state 52P3/2Requirement, generate for revising the control signal of semiconductor laser 1 operating frequency；
Step S11: semiconductor laser 1 adjusts its operating frequency according to described control signal, produces frequency revised 780nm pumping laser；
Repetition step S2 is to step S11, until the pump laser frequency that semiconductor laser 1 is exported stabilizes to make Rb atom from ground state 52S1/2It is energized into target excited state 52P3/2Till.
Wherein, described filtering method also includes:
Passed through the flashlight of linear polarization by polarizer 9, and make veiling glare only have the step that a linear polarization component passes through；And,
The step of the spurious rays polarized component passed through through polarizer 9 is filtered out by the analyzer 8 mutually orthogonal with polarizer 9.
In sum, in technical solution of the present invention, device 5～9 is the main part of atomic light filter, cross-polarization sheet 8,9 makes most of light all cannot pass through light filter, only those genetic methods under rubidium bubble 5 and magnetic field 6, heater 7 act on jointly draw the optical signal polarization direction of Semi-classical theory to rotate, thus transmission is gone out.
Laser instrument 1 is the emission source of pump light, and after isolator 2, dichroic mirror 3,4 introducing light filter derives residue optical signal again, then utilizes the optical signal of derivation to carry out frequency stabilization.Quarter-wave plate 10 and polarization spectroscope 11 are that circular component extracts light path, the main shaft of wave plate and countershaft and spectroscopical light splitting axle angle at 45 °, thus the left circularly polarized light of incident wave plate and right-circularly polarized light can be eventually converted into the component on two light splitting directions of polarization spectroscope.
Device 12～15 is the frequency stabilization circuit module of laser instrument.Owing to the spectrophotometric result of device 10,11 can not reach perfect, in addition the photoelectric transformation efficiency of photodetector 12,13 cannot be essentially equal, therefore the signal of telecommunication of two circular component needs through difference channel 14 pretreatment before subtracting each other, adjust background and amplification respectively, by testing regulation in advance, make two signals finally subtracted each other equal with the power proportions relation of incident illumination circular component, frequency stabilization effect otherwise can be caused to decline.Frequency offset is filtered and amplifies by frequency stabilization servo circuit 15, is finally provided to the wavelength management modules of laser instrument 1.For ECLD, usually it is loaded on the piezoelectric ceramics PZT of regulation external cavity length.
Through implementing technical solution of the present invention, the transmission spectral line of the excited state faraday anomalous dispersion atomic light filter of its internal frequency stabilization many transition line pumping is as shown in Figure 8, the maximum transmission rate situation of change that different pumping power obtains is as shown in Figure 9, high-transmission rate is up to 60%, central peak transmission bandwidth about 1.4GHz.
The above is only the preferred embodiment of the present invention; it should be pointed out that, for those skilled in the art, on the premise of without departing from the technology of the present invention principle; can also make some improvement and deformation, these improve and deformation also should be regarded as protection scope of the present invention.
Claims (4)
1. the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of a communication band, it is characterized in that, described light filter includes: semiconductor laser (1), laser isolator (2), coupling dichroism eyeglass (3), light splitting is with dichroism eyeglass (4), Rb atom steam bubble (5), magnetic field generator (6), heater (7), analyzer (8), polarizer (9), the quarter-wave plate (10) of 780nm, polarization splitting prism (11), first photodetector (12), second photodetector (13), difference engine (14) and frequency stabilization servomechanism (15)；
Described semiconductor laser (1) is tunable 780nm semiconductor laser, and it is used for providing Rb atomic ground state 52S1/2To target excited state 52P3/2Pumping laser；
Described laser isolator (2) is used for guaranteeing that pumping laser signal is unidirectional and passes through, and cuts off by the optical signal reflected on rear class optics；
Described coupling dichroism eyeglass (3) is arranged between described analyzer (8) and Rb atom steam bubble (5), and be positioned on the transmitted light path of described laser isolator (2), it is set to 1529nm light highly transmissive, and 780nm light height is reflected, it is for reducing the loss of flashlight as far as possible while pumping laser is introduced light filter light path；
Described light splitting dichroism eyeglass (4) is arranged between described Rb atom steam bubble (5) and polarizer (9), and be positioned on the transmitted light path of described Rb atom steam bubble (5), it is set to 1529nm light highly transmissive, 780nm light height is reflected, it is for extracting pump light from light filter light path, in case carrying out frequency stabilization in rear class light path, reduce the loss of flashlight as far as possible simultaneously；
Described Rb atom steam bubble (5) is arranged on described coupling dichroism eyeglass (3) reflected light path, and bubble uses quartz material, and it is set to all possess high-transmission rate at near-infrared 780nm and 1529nm；
Described magnetic field generator (6) is arranged on described Rb atom steam bubble (5), and it is for producing the external magnetic field signal for acting on Rb atom steam bubble (5)；Magnetic field is selected to be operated between 450G to 600G, now the 5 of Rb atom2S1/2(F=2) → 52P3/2The low frequency wonder division zone of transition band and 52S1/2(F=3) → 52P3/2The high frequency drift division zone of transition overlaps, it might even be possible to formed than Absorption Line higher before mangneto division；
Described heater (7) is arranged on described Rb atom steam bubble (5), its operating temperature being used for controlling described Rb atom steam bubble (5)；
Described analyzer (8) and polarizer (9) are arranged at the light path two ends of described Rb atom steam bubble (5), described analyzer (8) is set to mutually orthogonal with polarizer (9), described polarizer (9) is positioned to allow for the flashlight of linear polarization and passes through, and makes veiling glare only have a linear polarization component to pass through；Described analyzer (8) is set to by the spurious rays polarized component that filter out through polarizer (9) pass through mutually orthogonal with polarizer (9)；
The quarter-wave plate (10) of described 780nm, it is arranged on the reflected light path of described light splitting dichroism eyeglass (4), and it is for becoming the line polarized light on wave plate main shaft and the angled direction of countershaft respectively by Left-hand circular polarization component and the right-hand circular polarization component of incident optical signal；
Described polarization splitting prism (11) is arranged on the exit path of described quarter-wave plate (10), it is for by the line polarized light beam splitting on the main shaft of quarter-wave plate (10) outgoing and countershaft direction, outgoing in the two directions, thus left circularly polarized light and the right-hand circular polarization light component of optical signal are extracted respectively；
Described first photodetector (12) is for will be converted into first signal of telecommunication the aforementioned left circularly polarized light extracted and export to difference engine (14)；
Described second photodetector (13) is for will be converted into second signal of telecommunication the aforementioned right-circularly polarized light extracted and export to difference engine (14)；
Described difference engine (14), for first signal of telecommunication of input and second signal of telecommunication are carried out signal subtraction, generates frequency offset signals；
Described frequency stabilization servomechanism (15) is for according to described frequency offset signals, generation feeds back to the control signal of described semiconductor laser (1), described control signal is used for adjusting the operating frequency of semiconductor laser (1), frequency of amendment offsets, thus optical maser wavelength is locked on the position that pumping efficiency is maximum.
2. the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of communication band as claimed in claim 1, it is characterized in that, in the light path of described Rb atom steam bubble (5), the other end of described polarizer (9) Rb atom steam bubble (5) relatively is additionally provided with tunable 1529nm lasing light emitter (16), and the other end of described analyzer (8) Rb atom steam bubble (5) relatively is additionally provided with the 3rd photodetector (17)；
Described tunable 1529nm lasing light emitter (16) is used for producing wavelength continually varying flashlight and is incident to Rb atom steam bubble (5) through polarizer (9), thus for the transmission case of one section of continuous wavelength range signals light of detection；
Described 3rd photodetector (17) is for being converted into signal of telecommunication record by the flashlight of analyzer (8) transmission, wavelength consecutive variations because of flashlight, the flashlight recording transmission the most continuously can be obtained by with wavelength as independent variable, absorbance is the curve of value, namely transmission spectrum.
3. the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of communication band as claimed in claim 1, it is characterized in that, the main shaft of described quarter-wave plate (10) and countershaft and the light splitting axle angle at 45 ° of described polarization splitting prism (11).
4. the ultra-narrow band excited state faraday anomalous dispersion atomic light filter of communication band as claimed in claim 1, it is characterized in that, described heater (7) is used for controlling described Rb atom steam bubble (5) and is operated in the arbitrary temp of room temperature to 200 DEG C.
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| CN105449512B (en) * | 2015-12-16 | 2018-04-24 | 山西大学 | One kind uses gas-solid interface Asia Doppler reflection spectrum offset frequency frequency regulator and method |
| CN105514797B (en) * | 2016-01-13 | 2018-07-24 | 山西大学 | Laser frequency lock device and method based on the hyperfine energy level spectrum of two-photon |
| CN105514795B (en) * | 2016-02-02 | 2018-07-24 | 山西大学 | Device and method based on the manipulation atom population transfer of speed selection technique |
| CN106329295A (en) * | 2016-11-07 | 2017-01-11 | 北京邮电大学 | Excited-state atomic optical filter based on hollow cathode lamp |
| CN106848824B (en) * | 2017-03-31 | 2019-03-29 | 中国科学院国家授时中心 | A kind of integrated laser system and method |
| CN108832477A (en) * | 2018-06-14 | 2018-11-16 | 山西大学 | Based on nano optical fibers ultra low power absorption spectrum frequency regulator and spectrum frequency stabilization |
| CN110911963B (en) * | 2019-11-01 | 2021-07-02 | 山西大学 | High-stability polarization spectrum frequency stabilizer |
| CN111817130B (en) * | 2020-06-22 | 2021-11-16 | 北京航天控制仪器研究所 | Pumping laser frequency stabilization device and method for SERF gyroscope |
| CN112039523B (en) * | 2020-09-04 | 2023-09-22 | 中国科学院精密测量科学与技术创新研究院 | Rubidium two-photon transition optical frequency scale based on polarization modulation |
| CN112018590B (en) * | 2020-09-07 | 2021-11-02 | 北京大学 | Multi-wavelength non-atomic resonance Faraday semiconductor laser |
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