CN101826700A - 2 mu m single mode fiber collimator with high coupling efficiency for semiconductor laser - Google Patents

Abstract

The invention discloses a 2 mu m single mode fiber collimator system with high coupling efficiency for a 2 mu m semiconductor laser. A 2 mu m single mode fiber coupler designed for a self-focusing lens with one fourth pitches is optimized according to the light transmitting principle of the self-focusing lens. The system consists of a 2 mu m testing light source, a single mode fiber collimator with high coupling efficiency, a fiber connector, and a 2 mu m laser power meter with high sensitivity. The single mode fiber collimator can be used for fiber coupling of parallel light at the same time so as to meet the requirements of a 2 mu m coherent laser Doppler wind finding radar receiving system on the fiber coupling of echoes, can realize all fiber and miniaturization of the receiving system, and successfully solves the problems of difficult alignment and adjustment and large occupied space of an optical axis. The single mode fiber collimator has the characteristics of high coupling efficiency, and high operability and repeatability, has the advantages of relatively low cost and easy realization, and has high practical value in the field of lasers and fiber coupling.

Description

A kind of 2 μ m single mode fiber collimator with high coupling efficiency for semiconductor laser

Technical field

The present invention relates to a kind of single mode fiber collimator with high coupling efficiency for semiconductor laser, particularly a kind of single mode fiber collimator that is used for the coupling of 2 μ m semiconductor laser high efficiency.

Background technology

Development along with laser technology, the operation wavelength of solid state laser that employing is mixed thulium and mixed holmium is near 2 μ m, this is than near the Injury Thresholds height of the Nd:YAG laser of operation wavelength 1 μ m to human eye, diode pumping solid laser is the focus that develops for over ten years recently, and its main feature is: system need not refrigeration, pump energy coupling efficiency height, stability is strong, good beam quality, the life-span is long, compact conformation.And the diode pumping solid laser about 2 μ m is the optimum Match of coherent laser radar, in order to improve resolution and the analysis precision that the microvortex flow disturbance is measured, has promoted 2 mu m coherent laser Radar Development.At present, states such as the U.S., Britain, Germany, France, Holland, Ireland, Japan all are devoted to the research of 2 μ m solid state lasers, detector, optical system and performance test and application facet such as measurement earth atmosphere, earth wind field.

So 22 mu m all-fiber coherent laser Doppler wind finding radars have become one of present research focus, no matter be spaceborne, airborne, still vehicle-mounted coherent laser Doppler windfinding radar is more and more paid attention to the requirement of miniaturization.Therefore, the way of the realization miniaturization that Radar Design master's master recognizes is exactly: utilize optical fiber to replace light path in the free space, replace the optics and the adjusting mechanism thereof of free space with the miniaturization optical fibre device.Simultaneously, utilize optical fiber can overcome the nonlinearity erron that environmental interference and some light-splitting devices are brought in the free space light path, the requirement of 2 full fiberizes of mu m coherent laser Doppler anemometry radar and miniaturization is also without exception, the main optical fibre device that uses is exactly a single mode fiber collimator in its system, this device is applied in the output of optics encapsulation single mode usually, light source-monomode fiber coupling, monomode fiber-photodiode coupling, optical fibre devices such as optical isolator and other field etc., it is wide that it has double window mouth operating wavelength range, low insertion loss, gradient-index lens encapsulates characteristics such as firm compact size, therefore, this device can be realized 2 full fiberize of mu m coherent laser Doppler anemometry radar and miniaturizations.

Single mode fiber collimator adopts gradient-index lens making cheaply, and product has low insertion loss, and the characteristic of low retroreflection adopts the G652 monomode fiber encapsulation of standard, the about 0.5mm of output beam diameter.Be widely used in laser diode, photodiode detector is in the system of optics such as acousto-optic modulator.Optical fiber collimator can use in pairs, is used for optical coupling being advanced/going out other optics.Therefore, optical fiber collimator is the desirable device of other device optical fiber coupling encapsulation.

The operation principle of optical fiber collimator as shown in Figure 1, the collimated beam diameter of optical fiber collimator (Collimated Beam Diameter, be called for short BD) and the full angle of divergence (Full Divergence Angle, be called for short DA), focal length (f) with lens, the core diameter of optical fiber (a), and the numerical aperture of optical fiber (NA) is relevant.Formula is as follows:

BD(mm)＝2f(mm)NA

DA(mrad)＝a(μm)/f(mm)

Wherein, NA: the numerical aperture of optical fiber; A: the core diameter of optical fiber; BD: beam diameter; DA: dispersion angle; F: the focal length of lens.

But, because the wave band of this 2 μ m belongs to internationally recognized extraordinary laser wavelength, fewer and the processing difficulties of coupled lens material that its transmitance is high, though it is very ripe at visible light and near infrared band monomode fiber coupling technique both at home and abroad, particularly external this wave band optical fiber collimator product of communication band { particularly } commercialization already, but do not appear in the newspapers as yet so far to single mode fiber collimator for the laser of 2 mu m wavebands.

At present, laser all adopts seed source to inject the mode of amplifying stage in the 22 mu m all-fiber coherent laser Doppler wind finding radar systems that domestic and international researcher is researched and developed, and general seed source is the good semiconductor laser of beam quality, adopt ordinary lens that semiconductor laser is carried out the optical fiber coupling, shortcoming is that the optical axis alignment between lens and the 9 μ m diameter fibre cores is regulated very difficult, simultaneously since lens and fiber core will be respectively by the optical adjusting frame adjusting that is coupled, make two optical adjusting frames will guarantee certain operating distance like this, occupied space can be very big, and it is very disadvantageous requiring for 22 mu m all-fiber coherent laser Doppler wind finding radar miniaturizations.

Summary of the invention

Therefore, based on the needs of 2 full fiberizes of mu m coherent laser Doppler anemometry radar and miniaturization, task of the present invention provides a kind of 2 μ m single mode fiber collimators.

On the one hand, the invention provides a kind of 2 μ m single mode fiber collimators of 2 μ m semiconductor laser high efficiency coupling, it is characterized in that: 2 μ m single mode fiber collimators of this 2 μ m semiconductor laser high efficiency coupling comprise 2 μ m semiconductor test light source and single mode fiber collimator with high coupling efficiency, also comprise the optical fiber connector and high sensitivity 2 μ m laser power meters.Described single mode fiber collimator with high coupling efficiency comprises gradient-index lens, glass bushing, metal sleeve, optical fiber contact pins, monomode fiber tail optical fiber.Wherein, the monomode fiber tail optical fiber penetrates and is fixed on the contact pin center, polishing is carried out on the contact pin surface after, gradient-index lens and optical fiber contact pins are put into glass bushing together realize aiming at; metal sleeve will be enclosed within the glass bushing outside simultaneously, play a protective role.Described gradient-index lens adopts inclined-plane, the spherical connection with ferrule end-face, the middle body of contact jaw keeps sphere, and the other parts of end face are processed into the inclined-plane, and the angle that makes end face and shaft axis of optic fibre is less than 90 °, can increase contact area like this, make optical coupling tightr.When end face and shaft axis of optic fibre angle are 8 °, insert loss less than 0.5dB, the loss of polishing inclined plane back reflection can reach 68dB.Simultaneously, the outer assembly of contact pin adopts metal or nonmetallic material, and the inclined-plane that contact pin contacts with gradient-index lens must carry out milled processed, and the other end adopts crooked limiting member to support optical fiber or optical fiber flexible-cable with release stress usually.Employed 2 μ m gradient-index lens focal lengths are 1.3mm, and length is 7.7mm, and radius is 1.8mm, and the focusing constant is 0.2mm ^-1, coupling efficiency is 26.8%.2 μ m semiconductor test light sources are launched laser under the effect of temperature controller, placing 2 μ m single mode fiber collimators in the laser beam axis direction is coupled to emitted laser, 2 μ m single mode fiber collimator outputs are connected with 2 μ m laser power meters by the optical fiber connector, therefore, the laser power that is coupled in the 2 μ m optical fiber cores can be passed through 2 μ m laser power meter observed readings.2 μ m semiconductor test light sources are launched laser under the effect of temperature controller, placing 2 μ m single mode fiber collimators in the laser beam axis direction is coupled to emitted laser, 2 μ m single mode fiber collimator outputs are connected with 2 μ m laser power meters by the optical fiber connector, therefore, the laser power that is coupled in the 2 μ m optical fiber cores can be passed through 2 μ m laser power meter observed readings.

In the 2 above-mentioned μ m single mode fiber collimators, described gradient-index lens is made by transparent material, and described transparent material comprises silicon chip and oxide glass etc.

In the 2 above-mentioned μ m single mode fiber collimators, the incident end face shape of described gradient-index lens is generally sphere, plane, ellipsoid, the conical surface and lozenges.

Further, two of described gradient-index lens end faces are coated with the anti-reflection film that increases testing light source emission light beam efficiency of transmission.

In the 2 above-mentioned μ m single mode fiber collimators, described glass bushing is made by two semi-synthetic, fastening circle tube members of special material, and described special material comprises K9 glass, melts quartz, pottery, transparent plastic.

In the 2 above-mentioned μ m single mode fiber collimators, described metal sleeve is made by metal material, and described metal material comprises gold, copper, aluminium, steel etc.

On the other hand, 2 μ m single mode fiber collimator spares to design utilize professional ZAMEX software to optimize.

The present invention introduces semiconductor laser in the system of monomode fiber coupling dexterously with 2 μ m single mode fiber collimators, has proposed by gradual index lens 2 μ m laser of Vernonia parishii Hook angle eye-safe to be carried out the idea of optical fiber coupling.

Take technique scheme, can realize the preparation of 2 μ m single mode fiber collimators, actual test coupling efficiency maximum can reach 25.4%, satisfied 2 mu m coherent laser Doppler anemometry radar receiving systems echo has been carried out the requirement that optical fiber is coupled, the full fiberize and the miniaturization of receiving system have been realized, successfully solve optical axis alignment and regulated the difficulty and the big defective that takes up space, in addition, the present invention has the coupling efficiency height simultaneously, the characteristics of workable and good reproducibility, and it is low to have both relative cost, the advantage that is easy to realize has very high practical value at laser to optical fiber coupling field.

Description of drawings

Below, describe embodiments of the invention in conjunction with the accompanying drawings in detail, wherein:

Fig. 1 is the operation principle schematic diagram of single mode fiber collimator;

Fig. 2 is the focusing characteristics schematic diagram of GRIN Lens;

Fig. 3 concerns schematic diagram between coupling efficiency and each parameter between GRIN Lens and the monomode fiber;

Fig. 4 is the general structural representation of 2 μ m single mode fiber collimators;

Fig. 5 is the structural representation of gradient-index lens;

Fig. 6 is the optical fiber contact pins structural representation;

Fig. 7 is the glass bushing structural representation;

Fig. 8 is gold-plated sleeve structure schematic diagram;

Fig. 9 is 2 μ m semiconductor laser structure schematic diagrames;

Figure 10 is 2 a μ m semiconductor laser optical fiber coupling test system structure schematic diagram.

Embodiment

General single mode fiber collimator mainly is made up of GRIN Lens and monomode fiber, the refractive index distribution gradient of grin rod lens, and refractive index of the centre is n ₀, from the refractive index at axle r place be:

$n\left(r\right)=n_0(1-\frac{1}{2}{\mathrm{Ar}}^2)---\left(1\right)$

Wherein: n ₀Be the axis refractive index, r is the GRIN Lens radius,

Focusing constant for GRIN Lens.The focal length of GRIN Lens is:

$f={\left[n_0\sqrt{A}\sin \left(\sqrt{A}z\right)\right]}^{-1}---\left(2\right)$

Wherein: z is the length of GRIN Lens.

By (2) formula as can be known, because A is the function of wavelength, so f also is the function of wavelength.As shown in Figure 2, under given wavelength condition, if z is long, then focus is in lensed endface; Otherwise z is too short, and then focus is outside lensed endface.Therefore, the error in length of lens will inevitably have influence on the light beam coupling effect, and this is the one of the main reasons that causes the collimater loss.

2 μ m semiconductor lasers are made up of the GRIN Lens of monomode fiber and 1/4 pitch to the coupled system of monomode fiber, the GRIN Lens purpose of using 1/4 pitch is to be convenient to machine work, again because the focus of the GRIN Lens of 1/4 pitch is convenient to the coupling debugging on end face.Coupling principle between them is similar with the coupling principle of ordinary lens, and the length of used GRIN Lens is:

$z=\frac{P}{4}=\frac{\mathrm{\π}}{2\sqrt{A}}---\left(3\right)$

Wherein: P is the pitch of GRIN Lens.Because P is under paraxial approximate condition, follows sinuous path according to meridian optical fiber and propagate and to determine.So inaccurate by the z value that formula (3) calculates, the aberration of the other GRIN Lens of loss when having brought coupling also can make coupling efficiency descend increases the loss of device.

When the length of GRIN Lens is 1/4 pitch, promptly $\sqrt{A}z=\mathrm{\π}/2,$ According to mould field coupled wave theory, optical field distribution is φ ₁Gaussian beam and φ ₂The coupling efficiency of Gaussian beam be:

$\mathrm{\η}=\frac{{\left|{\∫\∫\mathrm{\φ}}_1{\mathrm{\φ}}_2\mathrm{ds}\right|}^2}{\∫\∫{\left|{\mathrm{\φ}}_1\right|}^2\mathrm{ds}\∫\∫{\left|{\mathrm{\φ}}_2\right|}^2\mathrm{ds}}---\left(4\right)$

Utilization Gaussian beam transmission theory through further deriving, can obtain between GRIN Lens and the monomode fiber under axle coupling, drift angle coupling and 3 kinds of situations of spacing coupling the coupling efficiency between GRIN Lens and the monomode fiber respectively.

(1) be coupled as from axle between GRIN Lens and the monomode fiber:

${\mathrm{\η}}_1=\exp [-{\left(\frac{n_0\sqrt{A}\mathrm{\π}{x}_0{\mathrm{\ω}}_0}{\mathrm{\λ}}\right)}^2]---\left(5\right)$

(2) drift angle is coupled as between GRIN Lens and the monomode fiber:

${\mathrm{\η}}_2=\exp [-{\left(\frac{\mathrm{\θ}}{n_0\sqrt{A}{\mathrm{\ω}}_0}\right)}^2]---\left(6\right)$

(3) distance is coupled as between GRIN Lens and the monomode fiber:

${\mathrm{\η}}_3=\frac{2(1-{\mathrm{\ϵ}}^2)}{(2+{\mathrm{\ϵ}}^2)}---\left(7\right)$

Wherein,

$\mathrm{\&epsiv;}=\frac{{{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="H2009102174083E00013.png"\; state="\{\{state\}\}">n</figure-callout>}}_0}^2\mathrm{A\&pi;d}{{\mathrm{\&omega;}}_0}^2}{\mathrm{\&lambda;}}---\left(8\right)$

Here, ω ₀, λ is respectively the spot size and the wavelength of Gaussian beam; D is the spacing between GRIN Lens and the monomode fiber; x ₀Be the between centers spacing between GRIN Lens and the monomode fiber; θ is the angle between GRIN Lens and the monomode fiber.

Fig. 3 concerns schematic diagram between coupling efficiency and each parameter between GRIN Lens and the monomode fiber.The relation of having utilized MATLAB emulation between GRIN Lens and the monomode fiber between coupling efficiency and each parameter as shown in Figure 3, wherein Fig. 3 (a) is the relation of coupling efficiency and its axle base; Fig. 3 (b) is the relation of coupling efficiency and its angle; Fig. 3 (c) is the relation of coupling efficiency and its spacing, and as can be seen from the figure coupling efficiency descends rapidly with the increase of each parameter, and as can be seen coupling efficiency concerning the spacing coupling with respect to insensitive other two kinds of couplings.

Fig. 4 is the general structural representation of 2 μ m single mode fiber collimators.This optical fiber collimator comprises optical fiber pigtail 401, optical fiber contact pins 402, glass bushing 403, gradient-index lens 404, metal sleeve 407 and the optical fiber connector 406.According to the biography light principle of top GRIN Lens, be directed to the GRIN Lens of 1/4 pitch, 2 designed μ m single mode fiber collimators have been carried out optimal design.When converging light, can be transformed into parallel optical fiber or converge optical fiber through after the GRIN Lens from end face input of GRIN Lens.Single mode fiber collimator is the basic optical device in optical fiber telecommunications system and the optical fiber sensing system, and its purposes is that the Gaussian beam to transmission collimates or focuses on, to improve the coupling efficiency between light source and optical fiber.The characteristics of this single mode fiber collimator are to be coupled in the monomode fiber by the 2 μ m semiconductor lasers that the angle of divergence is very big.

For 2 μ m semiconductor lasers, if directly with 2 μ m semiconductor lasers and monomode fiber coupling, coupling efficiency can be because the optical fiber mode fields of elliptical laser mould field and circle symmetry match and reduces.Certainly, the loss that can come the minimizing pattern not match and bring by the distance that increases laser end face and fiber end face.But because the height of laser is dispersed, it is crooked more that the wavefront of gauss laser beam becomes when increasing operating distance, can cause the optical fiber beam Wave-front phase on crooked laser beam wavefront and plane to lose like this.Cause coupling efficiency to reduce equally.Therefore, improve coupling efficiency, not only will reduce the coupling loss that the spot size mismatch is brought, and will reduce the coupling loss that phase mismatch brings.Therefore, gradient-index lens is integrated in the flush end fiber end face, the graded index that mainly utilizes gradient-index lens 404 accumulates in optical fiber core diameter place with the light beam of diffusion and improves coupling efficiency, has increased operating distance simultaneously.Both overcome not matching of mould field, overcome the loss that not matching of phase place brought simultaneously again.

Owing to 2 μ m are extraordinary laser wavelengths of generally acknowledging both at home and abroad, the lens material that transmitance is high is very rare both at home and abroad, find the high permeability material also to process on request, and its cost is very high.Therefore, compromise is considered after all factors, utilizing Chinese Xi'an is the preparation that special oxide glass gradient-index lens is finished single mode fiber collimator with the material of dimension mechanics of communication Co., Ltd processing, and the characteristics of this material are in 2 mu m waveband transmitance height and handling eases.By Theoretical Calculation and utilize ZEMAX software to be optimized, the required GRIN Lens of preparation collimater has been processed in design, and its optimal design parameter is as shown in table 1.

Design parameter after table 1 collimater is optimized

2 μ m semiconductor lasers are coupled by GRIN Lens and optical fiber, demarcate the effective value of the coupling efficiency of prepared single mode fiber collimator, the coupling testing apparatus as shown in figure 10.

Used optical fiber all is Corning SMF-28 monomode fiber in the test, and 2 μ m light power meter models are 3A-FS, and measuring range is 60 μ W～3W, and Other Instruments parameter used in the test is shown in table 2 and table 3.

Table 22 μ m single mode semiconductor laser parameter

Table 32 μ m monomode fiber parameter and test data

2 μ m single mode semiconductor lasers are measured its power output with power, be decided to be benchmark, then 2 μ m semiconductor lasers are fixed on the sextuple adjustment rack, gradient-index lens 404 and optical fiber contact pins 402 are fixed on the pressing plate of two-dimentional adjustment rack motionless by sleeve pipe 403, under microscopical supervision, the sextuple adjustment rack of careful adjusting, make the Output optical power meter maximum of the optical fiber connector 406 of optical fiber contact pins 402 afterbodys, peak power output just compared with laser output power can calculate maximum coupling efficiency, obtaining maximum coupling efficiency by a large amount of tests is 25.4%, theoretical value after approaching to optimize, table with test results understand that it is correct optimizing the result.

Fig. 5 is the structural representation of gradient-index lens.This gradient-index lens comprise laser entrance face 502 and with the contacted inclined-plane 503 of optical fiber contact pins.The laser entrance face 502 of gradient-index lens is coated with the anti-reflection film that increases laser emitting laser-transmitting efficient, gradient-index lens adopts inclined-plane, the spherical connection with ferrule end-face, the middle body of contact jaw keeps sphere, the other parts of end face are processed into inclined-plane 503, the angle that makes end face and shaft axis of optic fibre is less than 90 °, can increase contact area like this, make optical coupling tightr.When end face and shaft axis of optic fibre angle are 8 °, insert loss less than 0.5dB, inclined-plane 503 polishing back reflection losses can reach 68dB.Employed 2 μ m gradient-index lens focal lengths are 1.3mm, and length is 7.7mm, and radius is 1.8mm, and the focusing constant is 0.2mm ^-1, coupling efficiency is 26.8%.Simultaneously, this inclined-plane 503 also is coated with the anti-reflection film that increases laser emitting laser-transmitting efficient.This gradient-index lens is made by the column transparent material.Described transparent material can be silicon chip and oxide glass etc.The described gradient-index lens plane of incidence can be the plane, also can be designed to sphere, ellipsoid, the conical surface and lozenges etc. according to concrete needs, and this is fine understanding for those of ordinary skill in the art.

Fig. 6 is the structural representation of optical fiber contact pins.This optical fiber contact pins comprise optical fiber core cover glass rod 601, fiber core 602, with the contacted end face 603 of gradient-index lens, optical fiber pigtail 604 and the optical fiber connector 605.Described optical fiber contact pins adopts inclined-plane, the spherical connection with the gradient-index lens end face, the middle body of contact jaw keeps sphere, and the other parts of end face are processed into the inclined-plane, and the angle that makes end face and shaft axis of optic fibre is less than 90, can increase contact area like this, make optical coupling tightr.When end face and shaft axis of optic fibre angle are 8 °, insert loss less than 0.5dB, the loss of polishing inclined plane back reflection can reach 68dB.Simultaneously, the outer assembly of contact pin adopts metal or nonmetallic material, and the inclined-plane that contact pin contacts with gradient-index lens must carry out milled processed, and the other end adopts crooked limiting member to support optical fiber or optical fiber flexible-cable with release stress usually.Described cover glass rod 601 is except the effect with fixed fiber core; because the making and the gradient-index lens outside dimension of its external diameter are complementary; therefore, this cover glass rod 601 also has the function of being convenient to gradient-index lens and optical fiber core coupling adjusting.Described optical fiber is generally the monomode fiber of SMF-28 type.The described optical fiber connector 605 are generally the FC/APC type; also can be made into connectorless as required; FU-FC/UPC; SU-SC/UPC; the SA-SC/APC type; the optical fiber connector 605 optical fiber cores are generally protected by ceramic rod; its end face generally also has 8 ° inclination angle; still play the isolation rear orientation light; reduce the effect of inserting loss; make and insert loss less than 0.5dB; the loss of polishing inclined plane back reflection can reach 68dB; for accurately aim at optical fiber as far as possible; requirement on machining accuracy to contact pin and glass bushing is very high, and this is fine understanding for those of ordinary skill in the art.

Fig. 7 is the structural representation of glass bushing.This glass bushing is generally made by transparent material, and described transparent material is K9 glass, quartz, pottery, transparent plastic etc.Fig. 7 (a) is depicted as the glass bushing longitudinal sectional drawing, and Fig. 7 (b) is the glass bushing transverse cross-sectional view, comprises outer surface 701 and inner surface 702.The aperture of described inner surface 702 and the diameter of gradient-index lens are complementary, the effect of glass bushing is that gradient-index lens and optical fiber contact pins are fixed to self inner 703 the inside, is convenient between gradient-index lens and the optical fiber according to the adjusting that must operating distance be coupled.Therefore, it is higher to be compared by the requirement of suface processing quality for glass bushing, could guarantee that like this laser can be coupled to optical fiber cable in-core portion expeditiously by gradient-index lens.

Fig. 8 is the structural representation of gold-plated sleeve pipe.This gold-plated sleeve pipe is generally made by metal material, and described metal material is gold, copper, aluminium and steel etc.Fig. 8 (a) is depicted as the glass bushing longitudinal sectional drawing, and Fig. 8 (b) is the glass bushing transverse cross-sectional view, comprises outer surface 801 and inner surface 802.The aperture of described inner surface 802 and the external diameter of glass bushing are complementary, and the effect of gold-plated sleeve pipe is the cover glass cover, make it do the time spent and be difficult for broken being subjected to external force.Because this gold-plated sleeve pipe mainly plays the effect of protection inner member, therefore lower to its requirement on machining accuracy, can make the metal sleeve in multiple aperture according to concrete needs.

Fig. 9 is 2 μ m semiconductor laser structure schematic diagrames.This 2 μ m semiconductor laser comprises three pins, is respectively pin 902, pin 903 and pin 904, also comprises the light-emitting area 901 of semiconductor laser simultaneously.The effect of the light-emitting area 901 of described semiconductor laser is that the semiconductor laser emitting laser is launched along optical axis direction, light-emitting area 901 encapsulates according to certain requirement in use simultaneously, have transparent material layer to make dustproof window above the light-emitting area 901, described transparent material is quartz, K9 glass and silicon chip etc.Described three pins 902,903 and 904 are generally positive pole, negative pole and the ground connection of semiconductor laser, and the order of different 2 μ m semiconductor laser positive poles, negative pole and ground connection may be different.

Described 2 μ m semiconductor lasers are generally according to order of the pin, be installed on the special semiconductor laser installing frame, this moment, 2 μ m semiconductor lasers just can be worked under the effect of thermostat, described thermostat has two output ports, one of them output is a current output terminal, and this port provides operating current for 2 μ m semiconductor lasers; Another output is the temperature control end, and it accurately controls the working temperature of 2 μ m semiconductor lasers, and temperature-controlled precision is generally 0.001 °, can keep laser output wavelength stable like this, and this is understandable to those skilled in the art.

Figure 10 is 2 a μ m semiconductor laser optical fiber coupling testing apparatus structural representation.This coupling testing apparatus comprises semiconductor laser thermostat 1001, semiconductor laser installing frame 1002,2 μ m semiconductor lasers 1003, gradient-index lens 1004, glass bushing 1005, optical fiber contact pins 1006, high sensitivity laser power meter 1007 and optical fiber pigtail 1008.Described semiconductor laser 1003 is installed on the semiconductor laser installing frame 1002, and semiconductor laser installing frame 1002 links to each other with semiconductor laser thermostat 1001.Described gradient-index lens 1004 and optical fiber contact pins 1006 are fixed together according to operating distance by glass bushing 1005, the optical fiber connector of the rear end of described optical fiber contact pins link to each other with 2 μ m high sensitivity light power meters, and the coupling performance in order to be coupled and to regulate and test 2 prepared μ m optical fiber collimators, usually glass bushing is fixed on the two-dimentional adjustment rack, simultaneously semiconductor laser installing frame 1002 is fixed on the sextuple adjustment rack, is put into the operating distance place of gradient-index lens 1004.

After all devices install, open the power supply of semiconductor laser thermostat 1001 and 2 μ m high sensitivity laser power meters 1007, can observe the reading of 2 μ m high sensitivity laser power meters 1007 this moment by the limit, the position spectrum of meticulous adjusting 2 μ m semiconductor lasers 1003 in limit and gradient-index lens 1004 is sought the numerical value and the position of maximum coupling efficiency.

Need to prove, before test, to demarcate and write down the variation relation of 2 μ m semiconductor lasers, 1003 power outputs earlier with operating current, when finding 2 μ m high sensitivity laser power meters, 1007 full-scale reading positions, just can calculate the maximum coupling efficiency of 2 μ m single mode fiber collimators like this.

It is emphasized that at last, a designed cover single mode fiber collimator by test calibration the effective value of coupling efficiency, test result shows, GRIN Lens optimal design result is feasible and reliable, this has important directive significance to next step 2 μ m single mode fiber collimator encapsulation and commercialization, is that the miniaturization development of 2 mu m coherent laser Doppler anemometry radars is laid a good foundation.

Certainly, according to the needs in the practical application, 2 μ m single mode fiber collimators of the present invention can also be used for the coupling of fiber laser and solid state laser, because the beam quality of two kinds of laser output laser is very good, so the coupling efficiency of two kinds of lasers will be higher than the coupling efficiency of the semiconductor laser at Vernonia parishii Hook angle, with after the ZEMAX software optimization as can be known two kinds of laser coupling efficiencies generally all more than 80%.It should be noted that embodiment structure and the technical scheme only in above each accompanying drawing at last in order to single mode fiber collimator of the present invention to be described, but unrestricted.Although the present invention is had been described in detail with reference to embodiment, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is made amendment or is equal to replacement, do not break away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (9)

1. 2 μ m single mode fiber collimators of μ m semiconductor laser high efficiency coupling, it is characterized in that: 2 μ m single mode fiber collimators of this 2 μ m semiconductor laser high efficiency coupling comprise 2 μ m semiconductor test light source and single mode fiber collimator with high coupling efficiency, also comprise the optical fiber connector and high sensitivity 2 μ m laser power meters, described single mode fiber collimator with high coupling efficiency comprises gradient-index lens, glass bushing, metal sleeve, optical fiber contact pins and monomode fiber tail optical fiber.Wherein, the monomode fiber tail optical fiber penetrates and is fixed on the contact pin center, polishing is carried out on the contact pin surface after, gradient-index lens and optical fiber contact pins are put into glass bushing together realize aiming at; metal sleeve will be enclosed within the glass bushing outside simultaneously, play a protective role.Described gradient-index lens adopts inclined-plane, the spherical connection with ferrule end-face, the middle body of contact jaw keeps sphere, and the other parts of end face are processed into the inclined-plane, and the angle that makes end face and shaft axis of optic fibre is less than 90 °, can increase contact area like this, make optical coupling tightr.When end face and shaft axis of optic fibre angle are 8 °, insert loss less than 0.5dB, the loss of polishing inclined plane back reflection can reach 68dB, and having isolated rear orientation light admirably influences laser.Simultaneously, the outer assembly of contact pin adopts metal or nonmetallic material, and the inclined-plane that contact pin contacts with gradient-index lens must carry out milled processed, and the other end adopts crooked limiting member to support optical fiber or optical fiber flexible-cable with release stress usually.Employed 2 μ m gradient-index lens focal lengths are 1.3mm, and length is 7.7mm, and radius is 1.8mm, and the focusing constant is 0.2mm-1, and coupling efficiency is 26.8%.2 μ m semiconductor test light sources are launched laser under the effect of temperature controller, placing 2 μ m single mode fiber collimators in the laser beam axis direction is coupled to emitted laser, 2 μ m single mode fiber collimator outputs are connected with 2 μ m laser power meters by the optical fiber connector, therefore, the laser power that is coupled in the 2 μ m optical fiber cores can be passed through 2 μ m laser power meter observed readings.

2. 2 μ m single mode fiber collimator systems according to claim 1 is characterized in that described gradient-index lens is made by transparent material.

3. 2 μ m single mode fiber collimator systems according to claim 2 is characterized in that described transparent material comprises silicon, oxide glass.

4. 2 μ m single mode fiber collimator systems according to claim 2 is characterized in that the incident end face of described gradient-index lens is shaped as sphere, plane, ellipsoid, the conical surface and lozenges.

5. 2 μ m single mode fiber collimator systems according to claim 2 is characterized in that, the both ends of the surface of described gradient-index lens are coated with the anti-reflection film that increases testing light source emission light beam efficiency of transmission.

6. 2 μ m single mode fiber collimator systems according to claim 1 is characterized in that, two semi-synthetic, the fastening circle tube members that described glass bushing is made by special material.

7. 2 μ m single mode fiber collimator systems according to claim 6 is characterized in that, described special material comprises K9 glass, melts quartz, pottery, transparent plastic.

8. 2 μ m single mode fiber collimator systems according to claim 1 is characterized in that described metal sleeve is made by metal material.

9. 2 μ m single mode fiber collimator systems according to claim 8 is characterized in that described metal material comprises gold, copper, aluminium, steel etc.

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