CN104518418A - High-power 671 nm laser obtaining method - Google Patents
High-power 671 nm laser obtaining method Download PDFInfo
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- CN104518418A CN104518418A CN201410822249.0A CN201410822249A CN104518418A CN 104518418 A CN104518418 A CN 104518418A CN 201410822249 A CN201410822249 A CN 201410822249A CN 104518418 A CN104518418 A CN 104518418A
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Abstract
The invention relates to a high-power 671 nm laser obtaining method, and belongs to the technical field of laser application. The method comprises the following steps: carrying injection locking on seed laser with weak power into a high-power laser diode with a normal temperature wavelength of 658 nm, and using a threshold value adjusting method to find the optimal injection points, so as to achieve the purpose of obtaining 220 mW single mode laser with the wavelength of 670.98 nm. The high-power 671 nm laser obtaining method disclosed by the invention is high in operability; the obtained lithium atom cooled laser is good in single mode performance and high in power.
Description
Technical field
The present invention relates to and propose a kind of high-power 671nm laser acquisition methods, belong to laser application technique field.
Background technology
How to obtain high-power elemental lithium D line resonance laser in recent years to receive much attention in the cold atom experiment and quantum degeneracy gas studies of lithium.The aerial wavelength of this laser is 670.98nm, requires that unimodality is good, current acquisition scheme or of a high price, or power output is lower.
Be limited to the impact of semiconductor doping material and progress at present, wavelength is that the luminous power of the semiconductor laser of 671nm is not high, only within 50mW, and the exocoel frequency stabilized carbon dioxide laser made of this type of laser tube, often can only be operated in below 10mW, not reach the power required by cold atom experiment far away.
From nineteen ninety-five lithium bose einstein condensation Rice University realize since, elemental lithium becomes the new lover in cold atom field gradually.For atom cooling, elemental lithium has two large advantages, and the first has very simple level structure, wherein comprises cyclical transition energy level, and it two is have very strong coupling with electromagnetic field.This two large advantage determines lithium and is well suited for application laser-cooling technology.The natural abundance of lithium comprises two isotope 6Li and 7Li.6Li is fermion, and 7Li is boson, can study the sub-Statistical Physics of two amounts like this from elemental lithium.For these two kinds of isotopes, we can apply the s scattering of wave length that Feshbach resonance regulates them easily.The resonance point that elemental lithium is wider and very light quality are the characteristics be delithted with in cold atoms experiment.
In order to obtain larger cold atom sample, often carry out pre-cooled atom by the technology of Magneto-Optical Trap.In order to optimize Magneto-Optical Trap, general way is that the intensity of cooling laser is fixed near saturation intensity, then improves the radius that laser power increases laser as far as possible.The radius of cooling laser increases, then charging ratio increases.Another key element is that laser spatial model requires that unimodality is good.The D line resonance laser of elemental lithium is exactly the cooling laser used when cooling lithium atom, and its acquisition is limited to two approach at present: dye laser and exocoel frequency stabilized carbon dioxide laser.The advantage of dye laser is the monochromatic light that can export watt magnitude, and its shortcoming is that maintenance work is very loaded down with trivial details, and intrinsic noise is comparatively large, needs very expensive pumping laser.In order to the spatial mode quality obtained, the feature output power limit of exocoel frequency stabilized carbon dioxide laser is within 50mW.Thus need follow-up laser amplifier measure to increase laser power.Two that use methods of amplifying are tapered amplifier and laser injection locking.The former way is that seed laser good for exocoel frequency stabilized carbon dioxide laser output mode is coupled in tapered amplifier, photon amplifies through avalanche type in conical cavity, and power output can reach 500mW, and its shortcoming is expensive, and if misoperation, easily tapered amplifier is burnt out.The way of the latter is similar, but current way is limited to choosing and the regulation technology of injection locking from laser tube, and the laser power thus obtained is lower, is only about 80mW, uses it as the cooling light of Magneto-Optical Trap, limits the quality of cold atom sample.There is another one scheme recently, adopt the method in all-solid state laser source, by the laser freuqency doubling of 1342nm, thus obtain the laser of 671nm high-power output, but program technical difficulty is high, be unfavorable for promoting.
Summary of the invention
The object of the invention is to overcome the costliness of 220mW lithium atom cooling laser access approaches and the high shortcoming of technical difficulty, propose a kind of high-power 671nm laser acquisition methods.The method is the high-power laser diode of 658nm with the seed laser injection locking normal temperature wavelength of weak power, to reach the object of the 670.98nm single-mode laser obtaining 220mW.
The present invention is achieved through technology:
Step one, adopts normal temperature (25 DEG C) wavelength within the scope of 658nm ± 1nm, the laser tube of more than power 300mW, and as the second level from laser, the first order adopts wavelength normal temperature to be the laser of 675nm from laser.
Step 2, select the laser of 670nm outside cavity gas laser generation as seed laser, by the adjustment that electric current, temperature and outer cavity are long, seed laser is adjusted to single module 670.98nm and exports, power is 1.4mW.Threshold values is used to regulate method that seed laser is injected the first order from laser with best decanting point.
The specific practice of described threshold value adjustment method is:
Step 2.1, regulates the first order from laser temperature to about 5 DEG C, the first order is exported in threshold value from laser, by the luminous power of the light power meter monitoring first order from laser;
Step 2.2, the first order after isolation and coupling optical path, uses two reflective mirrors that seed laser coupling is injected the first order from laser from laser;
Step 2.3, repeatedly regulates and is used for seed laser to be coupled into first from two reflective mirrors of laser, make the reading in light power meter reach maximum;
Step 2.4, then reduces the first order from the operating current of laser, repeats the operation of step 2.2-step 2.3, until when the full-scale reading of light power meter reaches non-Injection seeded laser 3 times, using injection locking state now as best injection locking point.
To be the first order from the wavelength of laser when threshold value differ with seed laser wavelength the prerequisite that described threshold method regulates is no more than about 4nm.
Step 3, the second level exports the second level from laser from laser at threshold values, with thermostat, the second level is stabilized in 70 degree from laser temperature, makes the second level increase 10nm from optical maser wavelength.
Step 4, the second level is from laser after isolation and coupling optical path, and the first order after Injection seeded laser step 2 obtained injects the second level from laser from laser, uses threshold values to regulate method to regulate, until find best injection locking point.
Step 4.1, the second level after isolation and coupling optical path, uses two reflective mirrors that first order laser coupled is injected the second level from laser from laser; By the luminous power of the light power meter monitoring second level from laser;
Step 4.2, passes through Fabry-Perot-type cavity (FP chamber) by the injection first order from the second level after laser from laser, observes the spectral line of the second level from laser;
Step 4.3, repeatedly regulates and is used for the first order to inject the second level from two reflective mirrors of laser from laser, make the reading in light power meter reach maximum;
Step 4.4, then the second level is reduced to 40 degree from laser temperature, increases the operating current of the second level from laser, by observing the signal in FP chamber, the second level is made to form smooth curve bottom laser line, using injection locking state this moment as best injection locking point.The second level now obtained is then the 670.98nm single-mode laser of 220mW from laser.
Beneficial effect
The inventive method is workable, and the lithium atom cooling laser unimodality of acquisition is good, and power is large.
Accompanying drawing explanation
Fig. 1 is the flow chart of the inventive method;
Fig. 2 is that the 671nm two-stage laser in embodiment injects locking device index path;
Label declaration: 1a-first photodiode, 1b-second photodiode, 1c-the 3rd photodiode, 2-FP chamber, 3a-first optical isolator, 3b-second optical isolator, 3c-the 3rd optical isolator, 4a-first polarization beam apparatus, 4b-second polarization beam apparatus, 4c-the 3rd polarization beam apparatus, 4d-the 4th polarization beam apparatus, 5a-first reflective mirror, 5b-second reflective mirror, 5c-the 3rd reflective mirror, 5d-the 4th reflective mirror, 5e-the 5th reflective mirror, 5f-the 6th reflective mirror, 5g-the 7th reflective mirror, 5h-the 8th reflective mirror, 5i-the 9th reflective mirror, 5j-the tenth reflective mirror, 6a-first cylindrical mirror, 6b-second cylindrical mirror, 6c-the 3rd cylindrical mirror, 6d-the 4th cylindrical mirror, 6e-the 5th cylindrical mirror, 6f-the 6th cylindrical mirror, 7a-the one λ/2 filter plate, 7b-the 2nd λ/2 filter plate, 7c-the 3rd λ/2 filter plate, 7d-the 4th λ/2 filter plate, 7e-the 5th λ/2 filter plate, 7f-the 6th λ/2 filter plate, 7g-the 7th λ/2 filter plate,
Embodiment
The seed laser injection locking normal temperature wavelength that the present invention proposes a kind of weak power is the high-power laser diode of 658nm, obtains the 670.98nm single-mode laser of 220mW.
Specific operation process is as follows:
Near 658nm, there is the cheap laser tube up to 300mW.The present embodiment have selected ML101F27 and the LPC826 that Mitsubishi is produced, and both prices are all at about 45 yuans.
Pick out the laser tube that ML101F27 and LPC826 normal temperature wavelength is longer, at 22 DEG C, the optical maser wavelength of outgoing is respectively 658.6nm and 657.6nm.The 670nm outside cavity gas laser that main laser adopts TOPTICA company to produce, peak power output is 2mW.By the adjustment that electric current, temperature and outer cavity are long, main laser is adjusted to single module 670.98nm and exports, power is 1.4mW.Because main laser power is only from 1/200 of laser power, far below injection locking requirement, thus select two-stage injection locking scheme: first with main laser inject a peak power output be the 675nm of 15mW from laser, then use the first order from the laser injection locking second level from laser.
Two export can reach 650mA from the current source current the controller of laser, and precision is 1 below μ A, and the temperature-control range of temperature controller is 10 DEG C to 75 DEG C.The difficulty of this injection locking is how to regulate light path make seed light and accomplish pattern matching from laser.Carry out threshold value adjustment, specific practice is: first regulating near threshold value exports from laser, seed injection light, after isolation and coupling optical path, by the luminous power of power meter monitoring from laser, now regulate two speculums being used for seed light being coupled into from laser, repeatedly regulating makes the reading in light power meter maximum, and then reduce from laser work electric current further, repeat operation above, until the full-scale reading of light power meter be not seed injection light time about 3 times.Through threshold value control method, can thinking that seed light is good with the pattern matching from laser, then increase the electric current from laser, by observing the signal in FP chamber, just very easily can find best injection locking point.The prerequisite that threshold method regulates is no more than about 4nm from the wavelength of laser when threshold value and seed light wavelength difference, otherwise exceed the growth that injection scope also cannot see power signal due to wavelength, and the first order realizes from laser injection locking easily via threshold method.Because the second level is from optical maser wavelength and seed light wavelength difference 13nm, want with threshold method, must first increase from optical maser wavelength: with thermostat, the second level is stabilized in about 70 degree from laser tube temperature, 10nm is increased from optical maser wavelength, then method is regulated the first order to be mated with from zlasing mode from laser and overlaps well by threshold value, then the second level is reduced to 40 degree from laser tube temperature, increases operating current, find injection locking point.If increase electric current to can not find decanting point, then increase temperature by a small margin, until find good injection locking point.
The present embodiment proposes a kind of 671nm two-stage laser and injects locking device, comprises wavemeter a, oscilloscope, first from laser, second from laser, main laser, wavemeter b, the first photodiode, the second photodiode, the 3rd photodiode, FP chamber, the first optical isolator, the second optical isolator, the 3rd optical isolator, the first polarization beam apparatus, the second polarization beam apparatus, the 3rd polarization beam apparatus, the 4th polarization beam apparatus, ten identical reflective mirrors, six identical cylindrical mirrors, eight identical λ/2 filter plates.
Annexation is: wavemeter a is connected with the first photodiode; Oscilloscope is connected with the second photodiode, and the light path of the second photodiode, successively through central shaft, first polarization beam apparatus in FP chamber, arrives the second reflective mirror; Be the first reflective mirror directly over first polarization beam apparatus, immediately below be λ/2 filter plate; The center of the first reflective mirror and wavemeter a, the first photodiode are positioned on straight line; The front-right of the first polarization beam apparatus is the second reflective mirror, is the 3rd reflective mirror immediately below the second reflective mirror; Be the second polarization beam apparatus immediately below one λ/2 filter plate, the center of the second polarization beam apparatus is in the front-left of the 3rd reflective mirror; It is the 3rd λ/2 filter plate immediately below second polarization beam apparatus; The positive left side of polarization beam splitter is followed successively by the 2nd λ/2 filter plate, the first optical isolator, the second cylindrical lens, the first cylindrical lens, the second level from laser; Be the 4th reflective mirror immediately below 3rd λ/2 filter plate, the front-right of the 4th reflective mirror is the 5th reflective mirror, is the 6th reflective mirror immediately below the 5th reflective mirror, and the front-left of the 6th reflective mirror is the 3rd polarization beam apparatus; The front-left of the 3rd polarization beam apparatus is followed successively by the 4th λ/2 filter plate, the second optical isolator, the 4th cylindrical lens, the 3rd cylindrical lens, first from laser device; Be the 5th λ/2 filter plate immediately below 3rd polarization beam apparatus, it is the 7th reflective mirror immediately below 5th λ/2 filter plate, 7th reflective mirror front-right is the 8th reflective mirror, is the 9th reflective mirror immediately below the 8th reflective mirror, and the front-left of the 9th reflective mirror is the 4th polarization beam apparatus; The front-left of the 4th polarization beam apparatus is as the 6th λ/2 filter plate, the 3rd optical isolator, the 6th cylindrical mirror, the 5th cylindrical mirror, seed laser; Being the 7th λ/2 filter plate immediately below 4th polarization beam apparatus, is the tenth reflective mirror immediately below the 7th λ/2 filter plate, and the front-left of the tenth reflective mirror is the 3rd photodiode, and the 3rd photodiode is connected to wavemeter b.
Light path and the course of work of 671nm two-stage laser injection locking device are: the laser that the 670nm outside cavity gas laser that seed laser adopts TOPTICA company to produce produces, seed laser is adjusted to single module 670.98nm export, power is 1.4mW, seed laser is respectively the 5th cylindrical mirror and the 6th cylindrical mirror of 150mm and 50mm by focal length, then carries out injection locking by the 3rd optical isolator, the 7th λ/2 filter plate, the 4th polarization beam apparatus, the 9th reflective mirror, the 8th reflective mirror, the 7th reflective mirror and the first order from laser successively; The first order arrives the 3rd polarization beam apparatus by cylindrical mirror, optical isolator and filter plate in an identical manner from laser; The first order arrives the second polarizing beam splitter mirror from laser by speculum, then optical isolator is passed through, the injection locking second level is from laser, make the light of generation by FP chamber and wavemeter a, observe, when finding the spectral line of the second level from laser by adhesive to seed laser spectral line, and bottom is smooth, then complete the injection locking of the second level from laser, what now show in wavemeter is seed laser wavelength, finally obtains the 670.98nm single-mode laser obtaining 220mW.
Claims (2)
1. a high-power 671nm laser acquisition methods, is characterized in that: specifically comprise the steps:
Step one, adopts normal temperature wavelength within the scope of 658nm ± 1nm, the laser tube of more than power 300mW, and as the second level from laser, the first order adopts wavelength normal temperature to be the laser of 675nm from laser;
Step 2, select the laser of 670nm outside cavity gas laser generation as seed laser, by the adjustment that electric current, temperature and outer cavity are long, seed laser is adjusted to single module 670.98nm and exports, power is 1.4mW; Threshold values is used to regulate method that seed laser is injected the first order from laser with best decanting point;
The specific practice of described threshold value adjustment method is:
Step 2.1, regulates the first order from laser temperature to 5 DEG C, the first order is exported in threshold value from laser, by the luminous power of the light power meter monitoring first order from laser;
Step 2.2, the first order after isolation and coupling optical path, uses two reflective mirrors that seed laser coupling is injected the first order from laser from laser;
Step 2.3, repeatedly regulates and is used for seed laser to be coupled into first from two reflective mirrors of laser, make the reading in light power meter reach maximum;
Step 2.4, then reduces the first order from the operating current of laser, repeats the operation of step 2.2-step 2.3, until when the full-scale reading of light power meter reaches non-Injection seeded laser 3 times, using injection locking state now as best injection locking point;
Step 3, the second level exports the second level from laser from laser at threshold values, with thermostat, the second level is stabilized in 70 degree from laser temperature, makes the second level increase 10nm from optical maser wavelength;
Step 4, the second level is from laser after isolation and coupling optical path, and the first order after Injection seeded laser step 2 obtained injects the second level from laser from laser, uses threshold values to regulate method to regulate, until find best injection locking point;
Step 4.1, the second level after isolation and coupling optical path, uses two reflective mirrors that first order laser coupled is injected the second level from laser from laser; By the luminous power of the light power meter monitoring second level from laser;
Step 4.2, passes through Fabry-Perot-type cavity by the injection first order from the second level after laser from laser, observes the spectral line of the second level from laser;
Step 4.3, repeatedly regulates and is used for the first order to inject the second level from two reflective mirrors of laser from laser, make the reading in light power meter reach maximum;
Step 4.4, then the second level is reduced to 40 degree from laser temperature, increases the operating current of the second level from laser, by the signal in observation Fabry-Perot-type cavity, the second level is made to form smooth curve bottom laser line, using injection locking state this moment as best injection locking point; The second level now obtained is then the 670.98nm single-mode laser of 220mW from laser.
2. one according to claim 1 high-power 671nm laser acquisition methods, is characterized in that: to be the first order be less than or equal to 4nm from the wavelength of laser when threshold value and seed laser wavelength difference to the prerequisite that described threshold method regulates.
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2014
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