CN102290706B

CN102290706B - Method for generating stable, full-time low noise laser output

Info

Publication number: CN102290706B
Application number: CN 201110201112
Authority: CN
Inventors: 罗宁一; 何克祥; 范辉; 季朝华; 刘理; 何骏
Original assignee: Pavilion Integration Suzhou Co Ltd
Current assignee: Pavilion Integration Suzhou Co Ltd
Priority date: 2011-07-19
Filing date: 2011-07-19
Publication date: 2013-02-06
Anticipated expiration: 2031-07-19
Also published as: CN102290706A

Abstract

The invention discloses a method for generating stable, full-time low noise laser output. The method includes the following steps: regulating and maintaining a semiconductor laser operating temperature by means of a thermoelectric controller (TEC) attached on the laser; generating a direct-current bias from a direct-current generator; generating an amplitude-modulatable radio frequency signal from a local oscillator; superposing the radio frequency signal onto the direct-current bias to generate amplitude-modulatable drive current; injecting the amplitude-modulatable drive current into the semiconductor laser by way of input-coupled impedance matching; regulating the direct-current bias by means of an automatic power control circuit; and optimizing the amplitude of the radio frequency signal. By modulating the driving of the semiconductor laser diode, the method effectively overcomes the mode hopping phenomenon, the method is applicable to laser diodes with various wavelengths, the generated laser output has the advantages of low coherence, low noise, little speckles, long-time stable output power and long-time uniform beam illumination, and the method is particularly suitable for biomedicine and medical diagnosis and clinic.

Description

A kind of method that produces the low noise Laser output of stable, full-time

Technical field

The present invention relates to field of semiconductor lasers, relate in particular to a kind of can effectively produce have low relevant, low noise, the long-time long-time uniformly semiconductor laser system of stable and light beam illumination of low speckle and power output, and the semiconductor laser system of the various wavelength that required monochrome or polychrome originate in single device in biomedical and medical diagnosis and clinical practice.

Background technology

Semiconductor laser system reaches clinically many application based on the laser-induced fluorescence (LIF) radiation at biomedical and medical diagnosis.By structure of matter character is determined in the fluorescigenic detection of lure.The laser-induced fluorescence (LIF) process is absorption and the conversion process of a photon.Irradiation optical excitation molecule then sends more long wavelength's light.Because the luminescent spectrum of different molecular is different, just can survey and differentiate different molecular according to the characteristic spectral line of molecule.Because only in the absorption level coupling of irradiation optical wavelength and tested molecule, could effectively produce fluorescence signal, so according to different application, need to select different lasers or use tunable laser or select suitable tracer material for specific laser, be generally fluorescein or fluorescent dye.

As a kind of probe, the privileged site that fluorescein can be combined in biomolecule reacts specific optical maser wavelength.Most of fluorescein is made of the chemicals with phenyl ring, with the privileged site of tested molecule strong especially affinity is arranged.The narrow-band spectrum fluorescein is particularly suitable for the Multi Colour Lasers system.Used optical maser wavelength should conform to the absworption peak of fluorescence probe.Novel three low (the low speckle of low relevant low noise) semiconductor laser system that U.S. PIC application photoelectricity company produces can produce multiple different wave length and adapt to various dissimilar fluorescence probes.The mensuration that comprises deoxidation desugar nucleotide sequence based on the main application of laser-induced fluorescence (LIF) principle, laser display system, laser scanning confocal microscopy, protein scanner, stream type cell analyzer, cell sorting etc.

Deoxidation desugar nucleic acid is the carrier of organism hereditary information, is one and mutually twines the double-stranded macromolecule of the right hand that forms together by two polynucleotide chains, and wherein complementary nucleoside base forms coplanar base-pair by interaction of hydrogen bond.The specific function of deoxidation desugar nucleic acid is determined by the order of nucleic acid base.Human nucleic acid base only has four kinds: A, and G, C, T consists of 23 kinds of chromosomes.Various chromosomal length have a great difference: from the shortest Y chromosome (approximately containing 50,000,000 base-pairs) to No. 1 the longest chromosome (having 2.23 hundred million base-pairs).Human gene contains approximately 3,000,000,000 base-pairs altogether.Approximately the human gene of ten Percent contains protein coding sequence information.It is maximum that No. 1 chromosome comprises gene dosage, and nearly 3141 of its number genes account for about 8% of base-pair total amount in the human genome, decode difficulty also maximum.The defective that exists in these genes is relevant with 350 kinds of diseases, comprising cancer, Parkinson's and Alzheimer's disease etc.As the fluorescence method of one of most important invention of deoxidation desugar determining nucleic acid sequence technology than other method such as film radiography efficient at double even become the order of magnitude to improve, and good reproducibility, few with the sample amount, radiationless, be fit to the automatic sequencing of deoxidation desugar nucleic acid, also make the human genome sequencing become possibility.In the deoxidation desugar nucleic acid sequencing commonly used fluorescent dye at visible light with absworption peak.The most frequently used excitaton source comprises the argon ion laser that produces 488 nanometers or 514 nanometers at present.Absworption peak also has very large attraction near infrared fluorescent dye.Reason is background noise lower in signal collection, thereby has improved mensuration sensitivity.The absworption peak that for example excites with 780 nano lasers of existing report is at the fluorescent dye of 766,768 or 787 nanometers now.Deoxidation desugar nucleic acid sequencing can adopt monochrome, double-colored or four looks.

Imaging system has important application in medical diagnosis.Medical imaging device can be single channel such as tomoscan or multichannel such as nulcear magnetic resonance (NMR).Can pass through X-light transmission imaging or ultrasonic reflections imaging or optics (laser or non-laser) imaging.Also the spin density of conductivity or nulcear magnetic resonance (NMR) and relaxation time imaging can be fallen into oblivion such as radiation by other physical phenomenons.The resolution of optical imagery and signal to noise ratio are all higher, are usually used in introscope, laryngoscope, and Sigmoidoscope.Recently also be used for optical fault scanning.Many medical optical imagings system is based on the laser-induced fluorescence (LIF) radiation.Because most of organism is less to the wave band absorption of 650 to 1000 nanometers, the development of near infrared imaging technology is quite fast, and spatial resolution can reach 60 to 30 microns, and penetration depth is 6 to 10 centimetres.Outside inferior, take egfp as the gene expression video picture that indicates gene also is important optical molecular imaging mode, can be used for the discovery of small tumor focus and the screening of new drug etc.The advantage of laser display system is pure RGB primary colours, 3-dimensional image effect, high pixel resolution, large contrast, and high brightness.At present the laser display system urgent problem is the smudges that the high coherence because of light brings.

Laser scanning confocal microscopy adopts the fluoroscopic image pattern and adopts the spatial filtering technology to eliminate light out of focus or dazzle, helps to improve the quality of image.Laser scanning confocal microscopy can be controlled the depth of field, and the sampling by to a series of optical cross-sections obtains 3-dimensional image.3-dimensional image has important application at medical diagnosis, for example obtains the information of adult bone marrow cell or islet cells.The use laser scanning confocal microscopy can not only observe chemically constant cell or organ can also be observed cell alive or organ.Laser scanning confocal microscopy also has important application aspect ophthalmology, as can be used for live cornea research, for the monitoring of the diagnosis of keratitis and curative effect provide real-time three only image show.Laser scanning confocal microscopy also can be used for the eyeground tomoscan, analyzes retinal thickness, optical fundus blood vessel radiography etc.

The stream type cell analyzer measurement is suspended in the particle (cell) in the fluid.Cell sorting then is the expansion of this technology, according to the parameter of defined the cell subsets of appointment is sorted out from whole colony, in order to they are are further researched and analysed.Stream type cell analyzer is by optical component, opto-electronic conversion, and Electronic Control, fluid and data processing etc. partly form.Optical component comprises light source (laser or arc lamp), detector (photomultiplier), and by the device (optical filtering, reflection/transmission mirror) of spectral separation light beam.The major advantage that adopts laser to make light source is monochromatic, directivity, and coherence.The operation principle of stream type cell analyzer is that cell to be measured is put into sample cell behind the specificity fluorescent dyeing, enters the flow chamber that is full of sheath fluid under the pressure of gas.The cell defiled is by the ejection of the nozzle of flow chamber under the constraint of sheath fluid, forms cell column and intersects vertically with the laser beam of incident.Cell in being suspended in fluid is one by one by by the passage of Ear Mucosa Treated by He Ne Laser Irradiation, is induced to send fluorescence with fluorescence probe or the antibody of Cell binding.By the laser of cell scattering can be forwardly or the side collected.The light intensity of scattering is forward determined by particle size (surface area).Sidewise scattered light intensity then reflects shape and the optical homogeneity thereof of particle.If be cell by the particle of Ear Mucosa Treated by He Ne Laser Irradiation, then before scattering provide the information of cells involved ruffling, thereby distinguish dead cell and living cells.The sidescattering signal can be used to distinguish granular cell and non-particulate cell.How many fluorescence intensities of being sent by fluorescence probe is directly proportional with binding site.Result according to Fluorescence Characteristic and scattering can be with cell classification.Stream type cell analyzer has monochrome or polychrome.Optical maser wavelength commonly used has ultraviolet, 405,488,635 nanometers at present.The example that many use 560 to 600 nanometer gold-tinteds are also arranged recently.Compare with blue green light (488 nanometer), use gold-tinted (561 nanometer) can improve six to seven times of the detection sensitivities of some fluorescin (such as absworption peak at the PE of 558 nanometers and the absworption peak DsRed in 565 nanometers).

Stream type cell analyzer is mainly used to analyze the blood cell sub-group of classification belt surface mark, has a wide range of applications in clinical medicine domain.Application in oncology comprises (1) evaluation somatotype tumour cell, finds precancerous lesion, assists early diagnosis of tumor; (2) times body/non-times of body state of monitoring cell is for diagnosis, the prognosis of tumour are judged and treatment provides strong foundation.Application in clinical cellular immunity: to the cell surface antigen analysis, carry out cell classification and subgroup analysis by fluorescent antigen antibody test technology, evaluator body cell immunologic function.Application in diagnosis of hematological diseases and treatment comprises (1) leukemic immunity classification, diagnosis and treatment; (2) diagnosis of other kind quasi-blood disease such as paraoxysmal nocturnal hemoglobinuria and treatment monitoring: mensuration and the clinical practice of (3) granulophilocyte, for the treatment monitoring of the judgement of stem cell transplantation operative results, anaemia, tumour patient chemicotherapy provide foundation to the inhibition situation of marrow etc.Application in thrombus and hemorrhagic disease comprises the mensuration of (1) platelet function; (2) mensuration of platelet-associated antibody.

Another kind of important laser is used influencing each other based on laser and tissue.Laser can experience reflect after arriving tissue, and transmission absorbs, with scattering.Reflex should be avoided in clinical.The laser of transdermal can be treated the veins beneath the skin focus.Arrive retina if make laser pass intraocular liquid, then can carry out operation on retina.Laser injects that modal phenomenon is to absorb after the tissue.Most of absorbed smooth energy transform into heat energy causes the vaporization organized, blood coagulation, even peel off.Part luminous energy may be made it transition by Electron absorption.This can make tissue be in free or ionization state, the destruction of causing molecular link.Scattering phenomenon can affect light beam and focus on, and reduces the light beam penetration depth, is common in visible light and near infrared light.The degree of depth of laser penetration human body skin approximately is the secondary lifting function with its wavelength. and certainly, the kind of skin also determines penetration depth.In addition, the radius of light beam and collimation also can affect its penetrance.

The application of laser in the medical clinic applications treatment depends on that laser is to the effect of tissue.High-temperature effect is many to be caused by high energy laser, can impel tissue bulking, separately, with induced evaporation, vaporization.Utilize clinically this effect cutting or burn off tumour.If tissue is positioned at outside the laser spot, temperature rises slower, can reach clinically the purpose of coagulation.Micro-thermal effect or organize the fusion effect to be caused by the minimum area of smaller power Ear Mucosa Treated by He Ne Laser Irradiation.Can be used to fuse the micro-blood vessel that is truncated, micro-nerve, and fallopian tubal.For avoiding that surrounding tissue is caused nonselective heat injury, the pulsewidth of used laser should approach or be shorter than the thermal relaxation time of tissue.Photochemical reaction comprises that photodissociation is mainly caused by the laser of power below hundreds of milliwatts.Can be used to eliminate tumour.Photo electromagnetic effect or Photobiomodulation are by extremely low-energy laser initiation.Can promote wound healing, accelerate local circulation.The shatter effect of optoacoustic effect or light is used for the treatment of kidney stone or gall stone clinically.The moment that extremely short pulse causes, micro-thermal effect was applicable to ophthalmologic operation.The photospallation effect is generally caused by the deep UV that excimer laser produces.Cause textura epidermoidea to peel off.

Especially retina is relevant based on the interactional application of laser and tissue and eyes in a large number.For example use retinography screening diabetes type PVR.Early stage screening and in time treatment are very important.Retinal camera uses bright visible or infrared light to observe the eyeground.Decoding can obtain retina image-forming with the laser scanning eyeground and to reverberation.Can survey thus the degree of depth of eyecup and the thickness of retinal nerve fibre layer.The choroid retinal structure has four kinds of main assimilates: melanin is at retinal pigment epithelium, and absorption coefficient is higher than other assimilates, and weakens with the wavelength increase; Oxyhemoglobin is the biabsorption peak in 542 nanometers (green) and 577 nanometers (yellow); Reduced hemoglobin is absworption peak in 555 nanometers; There is inside and outside lamina reticularis in macula lutea lutein, is the most weak assimilate, and peak value is near 488 nanometers (blueness).Different wave length has different penetrating to retina.Blue light can be used to detect retinal nerve fibre layer mainly in surface scattering.The ruddiness penetration power is the strongest, can reach choroid.Green glow is then between between the two.The retinal vessel contrast is the strongest about 570 nanometers.When optical maser wavelength is lower than 540 nanometers or is higher than 580 nanometers, contrast reduction.

The ophthalmologic operation of laser comprises laser coagulation (diabetes type PVR, macular degeneration), laser cornea refractive art (myopia), and Angle of anterior chamber (glaucoma).Tradition is used 514 nanometer argon lasers or 532 nanometer green glows.577 nanometer gold-tinteds can be can be used to repair blood vessel by blood absorption.Excimer laser original position cornea edge art then is present modal corneal correction operation.

Optical coherence tomography is a kind of superhigh precision non-invasive imaging technology that develops rapidly in recent ten years, and dynamic time explanation image can be provided.Utilize the short distance coherence detection of biological of wideband light source to organize the different depth aspect to the back-reflection of incident weak coherent light or scattered signal several times, carry out space-time transformation and by scanning, can obtain biological tissue's two dimension or three-dimensional structure image.According to optical principle as can be known, the fault resolution of image and incident wave wavelength square is directly proportional and is inversely proportional to bandwidth.For example a centre wavelength is that 800 nanometer bandwidth are that the fault resolution of the light source of 100 nanometers can reach two microns.The lateral resolution of image is then determined by beam diameter.Optical coherence tomography has effectively overcome traditional video diagnostic technology, ultrasonic technology for example, because of biological tissue's live body to a large amount of scatterings of incident wave with absorb the limitation of bringing.As a brand-new imaging diagnosis technology, OCT has been widely applied at ophthalmology (as make fundus tissue visual), cardiology department's (as observing coronary artery and vulnerable plaque), oncology (as cancerous swelling invasive depth and Metastatic Lymph Nodes are passed judgment on) waits nearly all department.Except spatial coherence, the method for optical fault scanning also can be according to polarizability, and Doppler effect absorbs, and elasticity.The optical maser wavelength of medical optical coherence tomography instrument should be near infrared band: between 1.2 to 1.8 microns.

In addition, laser also can be applicable to skin surgery, with removing skin thin layer or excision/stitching blood vessel old or that damaged by the sun.The power of laser and wavelength determine concrete the application.Used wavelength should be able to gentleness pass skin also easily by water or pigment absorption.There is large water gaging to exist in the cell of living.Pigment in the skin then comprises hemoglobin and melanin.The absworption peak that these several materials are had nothing in common with each other.Gold-tinted more can be absorbed by hemoglobin than other color of light, can be used to treat the skin disease that vascular lesion causes, for example nevus flammeus (portwine stain), the birthmark of redness or purple, Marjoram Extract, schlempe acne, acne rosacea, hemangioma, and coppernose syndrome.Some gold-tinted also can be treated vergeture or lineae ablicantes, and to baby safe.Green glow can be used to treat optimum chromatodermatosis and becomes such as freckle, coffee spot and senile plaque expelling.Green glow also can be treated little blood vessel spider shape vein or the pore expansion of face and shank, and treatment skin shallow-layer pigment venereal disease becomes such as foxiness and removes orange red tattoo.Ruddiness then is commonly used to treat pigmentation such as freckle and the coffee spot of yellowish-brown or brown.Near-infrared is used to remove the pigment pathology of tattoo and skin depths such as 1064 nanometers.

The laser tattoo is removed based on laser energy the selectable skin that destroys around not injuring simultaneously of external pigment (carbon granules, dyestuff etc.).The removal of colored tattoo is the laser of palpus different wave length usually.For example, 1064 nanometers are used to remove black or navy blue tattoo.Red China ink is difficult for being removed by the light of 600-800 nanometer, adopts the green glow of 532 nanometers then much effective.Sapphire tattoo is used orange light (585 nanometer) and is removed.Green ink then should use ruddiness (650 nanometer) to eliminate.The laser that is used for the removal tattoo is usually operated at the Q impulse state.For adapting to the needs of various skin cares or beauty treatment, different laser systems is introduced skin surgery in succession.Existing market laser commonly used comprises the carbon dioxide CO2(10 of infrared wavelength.6 microns) and high power Er:YAG(1.55 microns) skin can successively gasify.Nd:YAG produces the laser of 1064 nanometers.Gold-tinted is many to be produced by organic dyestuff.Ruddiness or near-infrared are produced by ruby (Ruby, 694 nanometers) or alexandrite precious stone laser (Alexandrite, 700-818 nanometer).Green glow (532 nanometer) is then from the Nd:YAG after the frequency multiplication.For adapting to the needs of various medical diagnosiss and clinical practice, a large amount of laser systems is introduced in succession.Select the basic parameter of medical laser to comprise wavelength, power (or energy), and mode of operation.Existing medical laser syste mainly is selected from commercial device, as produce the excimer laser of ultraviolet or deep ultraviolet, the argon ion laser of output blue green light, produce the dye laser of gold-tinted or orange light, produce the helium neon laser of ruddiness or orange light, produce the carbon dioxide laser of infrared wavelength, and a series of solids or semiconductor laser, etc.Power output is from the milliwatt level to hundreds of watts.But continuous wave output or pulse output comprise various repetition rate.The extremely short pulse Laser output is generally realized by Q switching.

But the common complex structure of gas laser such as excimer laser and ion laser is heavy, operating difficulties, and the life-span is short, and is expensive, and pulse recurrence rate is low.Dye laser must frequent dyestuff, not only inconvenience and increase operating cost.Medical solid state laser mainly contains and produces ruddiness or near infrared ruby and alexandrite precious stone laser at present, produces the Nd:YAG of 1064 nanometers, produces 1.The Er:YAG of 55 microns infrared wavelengths.Can produce visible light even ultraviolet light by nonlinear frequency conversion.Modal as producing 532 nanometer green glows after the 1064 nanometer frequencys multiplication.Compare with other kind lasers, solid or semiconductor laser structure are much light and handy, and be easy to use, and the life-span is also long, and the trend that replaces gradually other lasers is arranged.But quite 488 and 514 nanometers sent of some useful wavelength such as argon ion laser can effectively be absorbed by fluorescein eGFP and TMR, and the method that but there is no effectively realizes in the structure of simple syndication by traditional mixing.The technology barrier that must overcome is the light noise that causes because of the green glow effect.For overcoming " green glow effect ", the two fundamental frequency light that participate in mixing must independently produce in the resonant cavity.Commercial mixing laser device must adopt many add-on assembles at present, cause complex structure, and conversion efficiency is low.

Because medical laser system is mainly taken from commercial device at present, still lack many useful wavelength, as 491,505 of important application is arranged in stream type cell analyzer, 556 nanometers, thereby quite a few medical diagnosis or clinical practice can't be finished even can't realize at all in the best condition.Especially in the Multi Colour Lasers system that adopts the narrow-band spectrum fluorescein, the coupling of optical maser wavelength and fluorescein absworption peak becomes especially important.In addition, because mostly huge structure is complicated, placed restrictions on the exploitation of portable instrument.The cost price of medical laser syste also is the key factor that determines the degree that is widely used.The novel semi-conductor laser system that the development of new laser is especially light and handy becomes the task of top priority.

The coherence of semiconductor laser comprises coherence time, coherence length, partially relevant, time coherence and spatial coherence.In biomedical and medical diagnosis and clinical practice, low-coherent light was learned and had been attracted a lot of sight in recent years.Actual solution that low coherence interference has been provided as absolute measurement, but remain an open question for the interference of the high coherent laser light source irradiation of tradition.The increase that low coherent laser is applied to spatial resolution obtains by low temporal coherence.The present invention is used for controlling semiconductor laser and is in low relevant method, based on the semiconductor laser principle with light feedback and tuned radio-frequency.

Stable, full-time low noise Laser output needs in the field of spectrum analysis important application is arranged in Medical Instruments, semiconductor manufacturing and many other.Hereinafter, As time goes on stable power, wavelength, frequency spectrum and the beam shape that means Laser output significantly do not change or be controlled in the permissible scope; The meaning of full-time low noise is that the optical noise of laser output is hanged down in all time but not only in operating process.

In order to keep semiconductor laser in the stable operation scope, often use thermoelectric controller (TEC).This traditional control method still, because the quick mode switching is invalid, only has limited impact to reducing optical noise.Automatic power control (APC) system can adjust the laser drive current of responsive feedback signal automatically.The limitation of this method comprise the mode hopping that prevents semiconductor laser and (or) the compartment model possible sign that lost efficacy and caused by useless light feedback and/or aging effect.

A kind of method of low noise laser surgey depends on the assembly average that the time becomes pattern.By regular change laser drive current, make it to be in below the laser threshold and the level between the maximum rated current high-frequency, for example, radio frequency (RF), semiconductor laser repeatedly open and close under frequency fast so that preponderate all the time without vertical pattern.This will make laser move under various modes and enlarge spectral region.Representative list of references is in United States Patent (USP) 5,065,401; 5,175,722; 5,197,059; 5,386,409; 5,495,464; 6,049,073; 6,625,381; With 6,999, in 838 as seen.

United States Patent (USP) 7468998 " the various wavelength of the low noise laser of outside photodiode sensor are used in the range degree of radio frequency modulation and automatic power control ", integral body is incorporated this case into for your guidance.But this method can not guarantee that the vertical pattern that generates is uncorrelated in each cycle, does not therefore have the random wavelength competition with having rapid wide participation laser surgey of vertical pattern of sufficient amount.Therefore, As time goes on assembly average is invalid.In addition, this method can't guarantee to be in closed condition when laser, or amplified spontaneous emission when lower power levels operates (ASE) is significantly suppressed.Consequently, no matter the rf modulations semiconductor laser is at RMS or peak-to-peak value if still can being produced the high noisy Laser output, especially when initial several seconds (preheating) and/or power supply supplier and/or suddenly change of environmental condition or perturbation.In addition, formerly technology is invalid or only partly effectively eliminates the light noise that wide gap III-V family semiconductor laser produces, and especially gallium nitride (GaN) is based on short wavelength's (typical blueness or purple) laser diode and gain guidance laser diode.The common demanding threshold current of these laser diodes, and because relatively strong spontaneous radiation can be identified multi-mode structure.The fabry-Perot type laser of gain guidance, spectrum width is that nanoscale gets, than the bandwidth that instructs laser wide at least two orders of magnitude also.Other challenges of GaN base laser rely on operating temperature and power supply strongly from its output spectrum.In addition, the technology field of illumination of failing to unify and stablize wide emit field laser formerly.

United States Patent (USP) 7468998 and 7606273 has been entrusted to same agent, consists of by reference, has disclosed to utilize the rf modulations drive current to reduce or eliminate the relevant optical noise of mode hopping and/or pattern subregion.As cip application, the present invention has solved the formerly weak point of technology effectively, and makes full-time low noise laser surgey in the wide wave-length coverage of space-time, spectrum, spatial stability.

Summary of the invention

In view of above-mentioned observation, the purpose of this invention is to provide a kind of from semiconductor laser the method for the full-time low noise Laser output of generation time, spectrum and spatial stability.Particularly about effectively being created in the novel semi-conductor laser system of the various wavelength that monochrome required in biomedical and medical diagnosis and the clinical practice or polychrome originate in single device.

A kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein said stablizing refers to that As time goes on laser output power, wavelength, spectrum and beam shape do not have obvious variation or be controlled in the permissible scope the described full-time full time that refers at each laser; May further comprise the steps:

Step 1: by the thermoelectric controller adjustment that is additional to laser and the operating temperature of safeguarding semiconductor laser;

Step 2: DC generator produces the generator direct current biasing, and wherein direct current biasing is determined by the ratio of required laser output power and the G-bar of the electric current-power curve of semiconductor laser approx;

Step 3: generate the radiofrequency signal of adjustable amplitude and frequency, be higher than the inverse of the rise time of the vertical pattern in the laser cavity of local oscillator far away;

Step 4: the superimposed RF signal to direct current biasing to generate the amplitude modulation drive current, make drive current and derivative leniently in time, change continuously;

Step 5: the amplitude modulation drive current is injected semiconductor laser by the impedance of input coupling matching;

Step 6: adjust direct current biasing by automatic power control circuit, and optimize the amplitude of radiofrequency signal;

The step of the adjustment direct current biasing in the described step 6 is further comprising the steps: with the outside photon-electron conversion equipment that outputs to of a part of laser, laser and any stray light are isolated fully; The electric current that the photon that amplification is received by the photon-electron conversion equipment is changed; The electric current that amplifies and the parameter of comparator compare, and wherein said parameter is predefined according to required laser output power; And the direct current biasing of adjusting according to comparative result;

The amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current to direct current biasing; Progressively improve the amplitude of radiofrequency signal and monitor simultaneously laser output power waveform and Laser output frequency spectrum; And select amplitude having at least a part of laser output power waveform to reach zero in each cycle, it is temporary close, and the Laser output spectrum becomes stable, described stable refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; In each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spontaneous emission is fully suppressed in the laser cavity.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: described semiconductor laser is edge emitter.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: described semiconductor laser is gallium nitrate based generating laser.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: described semiconductor laser is wide emit field generating laser.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: further comprising the steps of: by one or more nonlinear optical device conversion laser output frequencies.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: described semiconductor laser is the wide emit field generating laser by a plurality of transverse mode runnings, further comprise step: select the frequency of radiofrequency signal, make the average rate of change of amplitude modulation drive current be at least 0.1 mA/ns; The laser output region is even temporary transient stable beam shape all.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: further comprising the steps of: limit previous drive current and diversion reverse electric current for overload protection away from laser.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: further comprising the steps of: decay is along the high-frequency electromagnetic noise of power line conduction, to provide the laser electric energy by electron screening via the electromagnetic noise of power line transmission; With conductive box shielding laser, make the decay electromagnetic radiation penetrate described box body.

A kind of method that produces stable full-time low noise Laser output from semiconductor laser, As time goes on described stable laser output power, wavelength, spectrum and the beam shape of referring to do not have obvious variation or be controlled in the permissible scope, and described full-time finger is in the full time of each laser; May further comprise the steps:

Step 2: DC generator produces the generator direct current biasing;

Step 6: adjust direct current biasing by the automatic current control loop, and optimize the amplitude of radiofrequency signal;

Wherein, the step of the adjustment direct current biasing in the described step 6 is further comprising the steps: by electric current inductive reactance sampling direct current; Electric current and the parameter of comparator of sampling are compared, and wherein said parameter is adjustable to satisfy required laser output power when the application radiofrequency signal; And the direct current biasing of adjusting according to comparative result;

Wherein, the amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current to direct current biasing; Progressively improve the amplitude of radiofrequency signal and monitor simultaneously laser output power waveform and Laser output frequency spectrum; And select amplitude having at least a part of laser output power waveform to reach zero in each cycle, it is temporary close, the Laser output spectrum becomes stable, described stable refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; Namely in each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spontaneous emission is fully suppressed in the laser cavity.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: also comprise the intensity of tuning laser output, the step that laser is moved under pulse mode.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: comprise that also regular opening and closing direct current biasing is with the step of tuning laser output intensity.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein: further comprising the steps of: the pulse laser beam that injection is sent from semiconductor laser is to the solid state gain medium of optical pumping.

A kind of method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser, described diode refers to one or more semiconductor lasers; The emission of described semiconductor laser has the laser beam of the wavelength that the absorption spectrum with gain medium of solid laser is complementary; The described full-time full time that refers at each laser; May further comprise the steps:

Step 1: by being attached to the one or more thermoelectric controller adjustment on diode and the gain medium of solid laser and keeping diode and the operating temperature of gain medium of solid laser;

Step 5: the amplitude modulation drive current is passed through input coupling matching impedance injection diode;

Wherein, the step of the adjustment direct current biasing in the described step 6 is further comprising the steps: with the outside photon-electron conversion equipment that outputs to of a part of solid state laser, the optical cavity of solid state laser and diode and any stray light are isolated fully; The electric current that the photon that amplification is received by the photon-electron conversion equipment is changed; The electric current that amplifies and the parameter of comparator compare, and wherein said parameter is predefined according to the power output of required solid state laser; And the direct current biasing of adjusting according to comparative result;

Wherein, the amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current of diode to direct current biasing; Progressively improve the amplitude of radiofrequency signal and power output waveform and the output spectrum of while monitor diode; And select amplitude to reach zero at the power output waveform that has a part of diode at least in each cycle, it is temporary close, the diode output spectra becomes stable, wherein said stable refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; In each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spontaneous emission is fully suppressed in the laser cavity.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser, wherein: further comprising the steps of: adjust the diode operation temperature, make the absorption spectra of its output wavelength coupling solid state gain medium; Effective absorption of pump energy is optimised thus.

Preferably, above-mentioned a kind of method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser, wherein: described solid state laser gain medium is trivalent praseodymium dopant material, described diode is short wavelength GaN based laser diode.

The inventive method may further comprise the steps: the semiconductor laser of adjustment and attended operation temperature is by the attached TEC that is affixed on laser; Produce direct current biasing from DC generator; From the adjustable radiofrequency signal of local oscillator generating amplitude; The radiofrequency signal direct current biasing that is added to generates the amplitude modulation drive current; The amplitude modulation drive current injects semiconductor laser by input coupling impedance coupling; Adjust direct current biasing by automatic power control circuit; Optimize the amplitude of radiofrequency signal.According to the inventive method, automated power control stabilized lasers power output is in the level of being scheduled to, and rf modulations produces the Laser output that changes rapidly with continuous scanning wavelength.On average As time goes on, the Laser output spectrum is stable.Optimize the rf modulations degree with guarantee each rf period vertical pattern be random foundation, so mode hopping and/or pattern subregion are completely eliminated.In addition, any amplified spontaneous emission is largely suppressed.Therefore, the optical noise of Laser output during laser surgey all be low if having time.Not need " " of warming up.

According to the present invention, operate at a plurality of transverse modes in order to make wide emit field generating laser, radio frequency signal frequency mean variation rate is at least 0.1 mA/ns.Therefore, the transverse mode of side is for instantaneous or unsure state.After the statistical average, the laser beam waveform is that the space is unified and temporary transient stable.

According to the present invention, another kind produces space-time from semiconductor laser, and spectrum and spatial stability, method full-time, the low noise Laser output may further comprise the steps: the semiconductor laser of adjustment and attended operation temperature is by the attached TEC that is affixed on laser; Produce direct current biasing from DC generator; From the adjustable radiofrequency signal of local oscillator generating amplitude; The radiofrequency signal direct current biasing that is added to generates the amplitude modulation drive current; The amplitude modulation drive current injects semiconductor laser by input coupling impedance coupling; Adjust direct current biasing by the automatic current control loop; Optimize the amplitude of radiofrequency signal.Adopt automatic current control rather than automated power to control the stabilized lasers power output, when laser moves in the laser pulse pattern, be particularly useful.

According to the present invention, a kind of from the diode solid state laser method of the full-time low noise Laser output of generation time, spectrum and spatial stability.Wherein, " diode " refers to one or more semiconductor lasers, the emission of described semiconductor laser has the laser beam of the wavelength that the absorption spectrum with gain medium of solid laser is complementary, and said method comprising the steps of: by being attached to the one or more thermoelectric controller adjustment on diode and the gain medium of solid laser and keeping diode and the operating temperature of gain medium of solid laser; DC generator produces the generator direct current biasing; Generate radio frequency (RF) signal of adjustable amplitude and frequency, be higher than the inverse of the rise time of the vertical pattern in the laser cavity of local oscillator far away; The superimposed RF signal to direct current biasing to generate the amplitude modulation drive current; The amplitude modulation drive current is passed through input coupling matching impedance injection diode; Adjust direct current biasing by automatic power control circuit, and optimize the amplitude of radiofrequency signal.The step of adjusting direct current biasing is further comprising the steps: with the outside photon-electron conversion equipment that outputs to of a part of solid state laser, the optical cavity of solid state laser and diode and any stray light are isolated fully; The electric current that the photon that amplification is received by the photon-electron conversion equipment is changed; The electric current that amplifies and the parameter of comparator compare; And the direct current biasing of adjusting according to comparative result.

According to the present invention, the method further comprises because of overload protection restriction forward drive current and the diversion reverse electric current step away from laser.

According to the present invention, also further comprise step decay along the high-frequency electromagnetic noise of power line conduction, to provide the laser electric energy by electron screening via the electromagnetic noise of power line transmission; With conductive box shielding laser, make the decay electromagnetic radiation penetrate described box body, the method reduces the vulnerability to jamming of radiation, Conducted Electromagnetic Interference and raising laser.The realization of electricity screening washer has also reduced the optical noise of generating laser.

Outstanding effect of the present invention is: the invention relates to the novel semi-conductor laser system that can effectively be created in the various wavelength that monochrome required in biomedical and medical diagnosis and the clinical practice or polychrome originate in single device.That this system has is three low (low relevant, low noise, low speckle) and power output be the long-time uniform advantage of stable and light beam illumination for a long time.Technology is mainly manifested in: modulation is carried out in the driving to semiconductor laser diode; Effectively overcome Mode-hopping Phenomena; This technology can successfully be used for the laser diode of various wavelength.WhisperITTM laser module series take this technology as the basis can produce infrared, and as seen, the various spectrum of ultraviolet comprise common wavelengths 635,532, and 405 nanometers.Can pass through space or pigtail coupling, the frequency mixing technique of innovation has effectively been eliminated " green problem ", and a large amount of useful wavelength can be produced from the total solids device of light integration.The particularly important is many very useful and wavelength that be difficult to produce by conventional art can be by this class Semiconductor Laser acquisition in biomedical and medical diagnosis and clinical practice.This technology can reduce the function of smudges in addition, is well worth doing in Medical imaging systems.And light and handy, simple in structure, easy to operate, be suitable for portable instrument, thereby greatly simplified medical diagnosis system.

Following constipation closes the embodiment accompanying drawing, the specific embodiment of the present invention is described in further detail, so that technical solution of the present invention is easier to understand, grasp.

Description of drawings

Figure 1A is that the embodiment of the invention 1 is from the flow chart of the method for the full-time low noise Laser output of semiconductor laser generation time, spectrum and spatial stability;

Figure 1B is the program flow diagram that the embodiment of the invention 1 usefulness automatic power control circuit is adjusted direct current biasing;

Fig. 1 C is the program flow diagram that the embodiment of the invention 1 is optimized the radiofrequency signal amplitude;

Fig. 2 A is that the embodiment of the invention 2 is from the flow chart of the alternative method of the full-time low noise Laser output of semiconductor laser generation time, spectrum and spatial stability;

Fig. 2 B is the program flow diagram that the embodiment of the invention 2 usefulness automatic current control loops are adjusted direct current biasing;

Fig. 3 A is that the embodiment of the invention 3 is from the flow chart of the method for the full-time low noise Laser output of diode-pumped solid-state laser generation time, spectrum and spatial stability;

Fig. 3 B is effective absorption step that the embodiment of the invention 3 emission wavelengths rely on diode operation temperature and optimization pump energy;

Fig. 4 a ~ Fig. 4 b is the optics RMS noise of the embodiment of the invention 1 ~ 3, radiofrequency signal amplitude, the graph of a relation of output waveform and 488 nanometer laser spectrum, the wherein V of Fig. 4 a _Rf=0 V, RMS noise=0.18%; The V of Fig. 4 b _Rf=3.3 V, RMS noise=0.18%; The V of Fig. 4 c _Rf=4.9 V, RMS noise=0.09%; The V of Fig. 4 d _Rf=6.0 V, RMS noise=0.07%; V wherein _RfThe be added to maximum voltage of radiofrequency signal of direct current biasing of expression;

Fig. 5 is the full-time low noise Laser output of 488 nanometer laser modules of the embodiment of the invention 1 ~ 3, with prior art result's comparison diagram;

Fig. 6 is the time stabilized lasers operation figure according to 488 nanometer laser modules of the establishment of the embodiment of the invention 1 ~ 3;

Fig. 7 be the embodiment of the invention 1 ~ 3 at the instant stable spectrogram that sends from 488 nanometer laser modules of invention of measuring of different time;

Fig. 8 a is when operating temperature changes from 20 ℃ to 25 ℃, the stability diagram of the transverse profile of the GaN sound stage width territory generating laser of employing the inventive method;

Fig. 8 b is the stability diagram of transverse profile that does not adopt the GaN sound stage width territory generating laser of the inventive method.

Embodiment

Embodiment 1

The present embodiment discloses a kind of low noise laser module, and it is by realizing in the time stablizing on frequency spectrum and the space at outside a kind of rf modulations drive current of front end face photodiode and the optical power control system of using of laser module.

Shown in Figure 1A, to the introduction of the flow chart of inventive method, this inventive method has comprised the step that realizes adjusting and keeping the semiconductor laser operating temperature by a kind of semiconductor cooler that is fixed on the laser outside; Produce the direct current bias voltage from the direct current electric organ, wherein the size of direct current bias voltage is roughly according to the ratio of the G-bar of required laser output power and semiconductor laser current power curve; Produce the radiofrequency signal of an adjustable amplitude from local oscillator; Radiofrequency signal is added to produces modulated good drive current of amplitude on the direct current bias voltage; Resistance by a coupling is injected into semiconductor laser with the modulated good drive current of this amplitude; Adjust the direct current bias voltage by automatic power control circuit; Improve the amplitude of radiofrequency signal.Better, the waveform of radiofrequency signal and derivative can be in time passing and smoothly continual change, laser output wavelength can extend continuously like this.In addition, the frequency of radiofrequency signal is higher than the inverse of the makeup time of vertical pattern in the laser chamber.Resistors match is considerable for the GaN based laser diode that quite high spaning electrode voltage drop is arranged, because the frequency of radiofrequency signal is more quite a lot of than the height reciprocal of vertical pattern makeup time in the laser chamber.For the large tracts of land reflector that a plurality of transverse modes are arranged, the average rate of drive current will reach 0.1 mA/ns at least, and laser beam could be stable in time and space accordingly.

As shown in Figure 1B, the step of adjustment direct current bias voltage has further comprised the step of the complete a part of Laser output that separate with stray light to the photoelectric conversion device of laser outside.Amplification is accepted the electric current that photon converts to through the photoelectricity converter device, and the electric current after relatively amplifying in a comparator is regulated the direct current bias voltage according to comparative result again.With the standard of comparison of feedback current be predefined, laser output power just can conform to required standard when RF signal application like this.

What note emphatically is, even radiofrequency signal is employed, laser is at the multi-mode state as shown in the output spectrum that enlarges, and optical noise is still very high, unless the amplitude of radiofrequency signal to the memory of enough eliminating the cycle of operation in early stage, also will suppress amplified spontaneous emission greatly.Inevitable, the inventive method has comprised the step of optimizing the radiofrequency signal amplitude by monitoring laser device output waveform and spectrum.Only have and satisfied this last condition, the laser operations of a full-time low noise is just finished.Shown in Fig. 1 C, optimize radiofrequency signal amplitude step further comprise arrange the radiofrequency signal amplitude 0 and deducted the Limiting current value after the direct current bias value between, gradually increase the radiofrequency signal amplitude and monitor simultaneously laser output power waveform and output spectrum; Select in each circulation at least part of laser output power waveform and reach 0 amplitude (temporary close), especially time and surpass in laser chamber vertical pattern die-away time, the laser output spectrum becomes stable.After this, stable spectra means that spectrum broadens with the individual signals peak, and spectral envelope does not significantly change in time, and in addition, this stablizing can not have clear improvement with the amplitude of further increase radiofrequency signal.Stable spectra also is the signal of having eliminated pattern jumping and pattern subregion and significantly having suppressed spontaneous amplification radiation.

For the laser operation under pulse mode, the automated power control program of describing in Figure 1B may become invalid.The automatic current control loop that replaces can better use.

Embodiment 2

The present embodiment is shown in Fig. 2 A, and the method has comprised the step of adjusting and keep the semiconductor laser operating temperature by a kind of semiconductor cooler that is fixed on the laser, produces a direct current bias voltage from dc generator; Produce the radiofrequency signal of adjustable amplitude from local oscillator; Overlapping radiofrequency signal and direct current bias voltage produce amplitude modulated drive current; The input coupling of drive current after the amplitude modulation through being furnished with matched impedance is injected into semiconductor laser, adjusts the direct current bias voltage by automatically connecting the current control loop; Optimize simultaneously the radiofrequency signal amplitude.

Fig. 2 B has shown the step of adjusting the direct current bias voltage, further comprised by current sense resistance the direct current current sample, with comparator sample rate current and benchmark are compared, adjust the direct current bias voltage according to comparative result, preset with the benchmark of feedback current, laser output power just can meet required standard when RF signal application like this.

Embodiment 3

In the solid-state laser system, the intensity of fluctuation and/or the emission spectrum of pump laser may shake the light output of solid-state laser.Pumping source with time, spectrum and spatial stability, reference Fig. 3 A, solid-state laser System Construction flow chart shown in the present, the concrete method that makes the full-time low noise steady state operation of diode pumping solid-state laser comprises the steps, adjust and keep the operating temperature of diode, solid-state laser comes gain media by one or more thermoelectric controllers that are attached on the diode.Dc generator produces the direct current bias voltage, the direct current bias voltage roughly depends on the ratio of the G-bar of required laser output power and semiconductor laser current power curve herein, but produce the flat rate of wireless radiofrequency telecommunications number of adjusting amplitude from local oscillator, and this frequency is high in fact more quite a lot of than the inverse of vertical pattern settling time in laser chamber, the superimposed RF signal produces the drive current of modulating amplitude to the direct current bias voltage, by a discrepancy coupling of being furnished with matched impedance will modulate amplitude drive current be injected into diode, adjust the direct current bias voltage by automatic power control circuit, optimize simultaneously the radiofrequency signal amplitude.The step of adjusting the direct current bias voltage further comprises pays the step that the solid-state laser that partly isolates any stray light fully outputs to the photoelectric conversion device of solid-state laser optics cavity and diode outside, amplification is received the electric current that the photon conversion comes by photoelectric conversion device, with comparator the electric current that amplifies is compared with reference, adjust the direct current bias voltage wherein with reference to default according to the required power output of solid-state laser, and according to comparative result.

Fig. 3 B displays temperature depends on as the output wavelength of the typical laser diode of solid-state laser pumping source and optimizes the scheme of the absorption effect of pumping source by adjusting the laser diode operating temperature, and output wavelength is mated lasing absorption spectrum gain media like this.Shown in Fig. 3 B, it is at T that best coupling is found _OpCan be by finish the operating temperature of regulating laser diode such as thermoelectric controller.

As the most important application of the present invention, the inventive method can make under continuous wave or pulse mode produces blue, green, orange and red laser beam.In the full-time low noise stable state diode pumping Solid State Laser System that makes up according to the present invention, the solid-state laser material has multiple energy level allowed transition to blue, green, orange and red area, its example of material of this kind laser is trivalent praseodymium doped compound, pumping source is a kind of GaN base short wavelength laser, preferably large tracts of land emitter stable on short time, spectrum and space.

In order to protect semiconductor laser to avoid damaging, at Figure 1A, institute's elaboration method must further comprise the overload protection that limits forward current and the step of diversion reverse electric current from laser among Fig. 2 A and Fig. 3 A.This step can realize by the voltage regulator such as Zener diode that is connected in parallel on the semiconductor laser; this protective circuit has been arranged; maximum drive current is limited to Vz/Ri; wherein Vz represents Zener voltage; Ri represents the internal resistance of laser diode; the reverse drive electric current surpasses Vf/Ri never simultaneously, and Vf represents the Zener diode forward voltage.

In order to reduce radiation and to guide the to external world electromagnetic interference of environment, strengthen the anti-interference of semiconductor laser, at Figure 1A, institute's elaboration method must further comprise so that the step of the electromagnetic isolation module of semiconductor laser and external environment isolation among Fig. 2 A and Fig. 3 A, this step is by the electronics low pass filter of connecting circuit board, power line, the conductive shield box that covers on the laser module is realized.The another one benefit that realizes this step is further to have reduced the Laser emission noise.

The shortcoming of prior art is, the pattern that is based upon each rf period may be height correlation, and this is so that assembly average is As time goes on invalid, and ASE may be powerful to being enough to generation optical noise when the laser shutdown.In order to understand the importance of Optimum Operation parameter in the step of noise reduction and whole process, test, the result, by optics RMS noise wherein, the relationship description that adds radiofrequency signal amplitude and Laser output waveform and frequency spectrum is presented at Fig. 4.Fig. 4 a has shown Laser output waveform and the frequency spectrum when not having RF signal application to arrive drive current.Fig. 4 b has shown these attributes when the Amplitude Ratio direct current biasing of the radiofrequency signal that applies and the difference between the threshold current are little.Aspect the RMS noise reduction, do not improve.Fig. 4 c has shown that the amplitude when the radiofrequency signal that applies equals or during a little more than the difference between direct current biasing and the threshold current, light RMS noise increases considerably.Although frequency spectrum has enlarged, it is also unstable, and the existence of mode hopping and/or pattern subregion is described.This is actually the realization situation of most prior art.In this case, periodically opening and closing of laser.Yet the laser surgey turn-off time falls short of to such an extent that be enough to eliminate in the memory of the vertical pattern of upper one-period and suppresses ASE.The vertical pattern that the amplitude that further increase applies radiofrequency signal arrives on such level is based upon each cycle at random, and ASE is suppressed when laser attenuation, and such as the stable spectra that Fig. 4 d shows, full-time low noise laser surgey has realized.Flow chart description shown in Fig. 1 C optimize the step of radiofrequency signal amplitude.The parameter that is noted that optimization depends on the concrete characteristics of laser and the design of control circuit.Optimizing modulation depth is particularly important for wide gap III-V family semiconductor laser, particularly because more intense GaN base short wavelength (typical blueness or the purple) laser diode of spontaneous radiation.

Although RMS noise testing Fig. 4 b and Fig. 4 c are lower, they are not full-time low.(curve a) compares with the result (curve b) of free-running operation 488 nm lasers the full-time low noise Laser output of Fig. 5 display application GaN base laser from sending 488 nm coherent lights of the present invention.The visible curve a little noise that fluctuates is low, and is higher than the curve b large noise that fluctuates.

The time of the 488 nanometer laser modules of setting up according to the present invention as shown in Figure 6, is stablized power output.Advantageously, laser output power is stable, even the box temperature cycles of module.

According to the present invention, the assembly average by most of vertical patterns of generating in spectrum random and that constantly change has realized the laser surgey of full-time low optical noise and spectrum-stable.Shown in Fig. 7, from the spectrum of the GaN 488 nm laser modules emission of building according to the present invention, and the instant spectrum of measuring at different time is almost completely consistent, that is to say, reached the time stability of emission spectra.

For wide territory emitting laser, for spatially uniform and stability, the assembly average of transient or unstable state vertical and horizontal pattern is necessary.Obtain transient state or non-constant state model, laser drive current is the rf modulations with average rate of change of at least 0.1 mA/ns, like this within each modulation period, the competition of vertical pattern and transverse mode construction is incomplete, or in the sufficiently high frequency pattern that perturbs continuously, reach stable state to avoid the low order transverse mode.Curve shown in Fig. 8 a and Fig. 8 b just has some idea of because the present invention is in the application of laser module, when the ambient temperature temperature from 20 ℃ to 25 ℃, the horizontal waveform of the wide territory generating laser of GaN base is almost constant all the time.

The present invention still has numerous embodiments, and all employing equivalents or equivalent transformation and all technical schemes of forming all drop within protection scope of the present invention.

Claims

1. method that produces the low noise Laser output of stable, full-time from semiconductor laser, wherein said stablizing refers to that As time goes on laser output power, wavelength, spectrum and beam shape do not have obvious variation or be controlled in the permissible scope the described full-time full time that refers at each laser; May further comprise the steps:

Step 2: the DC generation device produces the electric organ direct current biasing, and wherein direct current biasing is determined by the ratio of required laser output power and the G-bar of the electric current-power curve of semiconductor laser approx;

Step 5: the amplitude modulation drive current is passed through input coupling matching impedance Semiconductor Lasers;

The step of the adjustment direct current biasing in the described step 6 is further comprising the steps: with the outside photon-electron conversion equipment that outputs to of a part of laser, laser and any stray light are isolated fully; The electric current that the photon that amplification is received by the photon-electron conversion equipment is changed; The electric current that amplifies and the parameter of comparator compare, and wherein said parameter is predefined according to required laser output power; And according to comparative result adjustment direct current biasing;

The amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current to direct current biasing; Progressively improve the amplitude of radiofrequency signal and monitor simultaneously Laser output waveform and Laser output frequency spectrum; And be chosen in and have at least a part of laser output waveform to reach zero amplitude in each cycle, and the Laser output spectrum becomes stable, described stable spectra refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; In each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spont-aneous emission is fully suppressed in the laser cavity.

2. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1, it is characterized in that: described semiconductor laser is edge emitter.

3. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1, it is characterized in that: described semiconductor laser is gallium nitrate based generating laser.

4. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1, it is characterized in that: described semiconductor laser is wide emit field generating laser.

5. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1 is characterized in that: further comprising the steps of: by one or more nonlinear optical device conversion laser output frequencies.

6. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1, it is characterized in that: described semiconductor laser is the wide emit field generating laser of a plurality of transverse mode runnings, further comprise step: select the frequency of radiofrequency signal, make the average rate of change of amplitude modulation drive current be at least 0.1 mA/ns; The laser output region is even temporary transient stable beam shape all.

7. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1 is characterized in that: further comprising the steps of: limit previous drive current and diversion reverse electric current for overload protection away from laser.

8. a kind of method that produces the low noise Laser output of stable, full-time from semiconductor laser according to claim 1, it is characterized in that: further comprising the steps of: decay is along the high-frequency electromagnetic noise of power line conduction, to provide the laser electric energy by electron screening via the electromagnetic noise of power line transmission; With conductive box shielding laser, decaying penetrates the electromagnetic radiation of described conductive box.

9. method that produces stable full-time low noise Laser output from semiconductor laser, As time goes on described stable laser output power, wavelength, spectrum and the beam shape of referring to do not have obvious variation or be controlled in the permissible scope, and described full-time finger is in the full time of each laser; May further comprise the steps:

Step 2: the DC generation device produces the electric organ direct current biasing;

Wherein, the step of the adjustment direct current biasing in the described step 6 is further comprising the steps: by electric current inductive reactance sampling direct current; Electric current and the parameter of comparator of sampling are compared, and wherein said parameter is adjustable to satisfy required laser output power when the application radiofrequency signal; And according to comparative result adjustment direct current biasing;

Wherein, the amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current to direct current biasing; Progressively improve the amplitude of radiofrequency signal and monitor simultaneously Laser output waveform and Laser output frequency spectrum; And be chosen in and have at least a part of laser output waveform to reach zero amplitude in each cycle, the Laser output spectrum becomes stable, described stable spectra refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; Namely in each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spont-aneous emission is fully suppressed in the laser cavity.

10. a kind of method that produces stable full-time low noise Laser output from semiconductor laser according to claim 9 is characterized in that: also comprise the intensity of tuning laser output, the step that laser is moved under pulse mode.

11. a kind of method that produces stable full-time low noise Laser output from semiconductor laser according to claim 10 is characterized in that: comprise that also regular opening and closing direct current biasing is with the step of tuning laser output intensity.

12. a kind of method that produces stable full-time low noise Laser output from semiconductor laser according to claim 9 is characterized in that: further comprising the steps of: the pulse laser beam that injection is sent from semiconductor laser is to the solid state gain medium of optical pumping.

13. a method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser, described diode refers to one or more semiconductor lasers; The emission of described semiconductor laser has the laser beam of the wavelength that the absorption spectrum with gain medium of solid laser is complementary; The described full-time full time that refers at each laser; May further comprise the steps:

Wherein, the step of the adjustment direct current biasing in the described step 6 is further comprising the steps: with the outside photon-electron conversion equipment that outputs to of a part of solid state laser, the optical resonator of solid state laser and diode and any stray light are isolated fully; The electric current that the photon that amplification is received by the photon-electron conversion equipment is changed; The electric current that amplifies and the parameter of comparator compare, and wherein said parameter is predefined according to the power output of required solid state laser; And according to comparative result adjustment direct current biasing;

Wherein, the amplitude step of the optimization radiofrequency signal in the described step 6 is further comprising the steps: the amplitude of radiofrequency signal is set to zero and deducts between the threshold current of diode to direct current biasing; Progressively improve the amplitude of radiofrequency signal and output waveform and the output spectrum of while monitor diode; And be chosen in and have at least a part of diode output waveform to reach zero amplitude in each cycle, the diode output spectra becomes stable, wherein said stable spectra refer to compose enlarge with unimodal and envelope frequency spectrum do not have any significantly over time, in addition, stable not showing along with the amplitude of further increase radiofrequency signal improves; In each rf period, the time of laser shutdown surpasses the relaxation time of any vertical pattern in the laser cavity; Namely during each laser shutdown, drive current fully is lower than threshold value, and amplified spont-aneous emission is fully suppressed in the laser cavity.

14. a kind of method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser according to claim 13, it is characterized in that: further comprising the steps of: adjust the diode operation temperature, make the absorption spectra of its output wavelength coupling solid state gain medium; Effective absorption of pump energy is optimised thus.

15. a kind of method that produces the low noise Laser output of stable, full-time from diode-pumped solid-state laser according to claim 13, it is characterized in that: described solid state laser gain medium is trivalent praseodymium dopant material, and described diode is short wavelength GaN based laser diode.