A kind of preparation method of optical fiber probe
Technical field
The invention belongs near field optic micrometering technical field, more specifically, relate to a kind of preparation method of optical fiber probe.
Background technology
The development of nanometer technology makes the optical measurement of submicrometer structure become and become more and more important, and due to the diffraction limit of traditional optical imaging method existence 1/2nd wavelength, the resolution of optical microscope is restricted.The birth of Near-field Optical Microscope has broken through this limitation, it is by the control of feedback system, with the probe of a needle point band nanometer aperture, at the near-field region of sample, scan, to obtain the evanescent wave signal that can reflect fine structure information, thereby reach the resolution of submicron order.
The performance quality of nano-probe is determining the image quality of Near-field Optical Microscope, especially the logical light rate of probe.Conventional is optical fiber probe at present, by drawing the method for cone or chemical etching to form the very little cone of needle point in optical fiber one end, by special coating process, finally at needle point, forms the aperture of Nano grade.The probe that draws taper to become is often bored long long, and the logical light rate of probe is sharply reduced, and causes signal strength detection to weaken, and resolution declines.On the other hand, although the method for conventional chemical etching can be prepared the probe of larger cone angle, the coarse injustice of its detecting probe surface, makes light signal generating scattering cause energy dissipation and signal distortion, affects image quality.Although many lithographic methods afterwards can improve the quality of probe, because its prepared probe is all linear taper, conical, be difficult to give full play to the effect that this factor of taper is improved logical light rate.
Summary of the invention
Above defect or Improvement requirement for prior art, the invention provides a kind of preparation method of optical fiber probe, can effectively prepare nonlinear conical probe, and the optical fiber probe surface topography making is smooth, be conducive to further further investigate taper and change the impact on the logical light rate of probe, thereby obtain the probe of near-field optical microscope of excellent performance.In addition, this method is with low cost, is easy to realize, and controllability is high, can manufacture.
For achieving the above object, the invention provides a kind of preparation method of optical fiber probe, it is characterized in that, comprise the steps:
(1) by HF solution and NH
4f solution is mixed to get etching solution, and the organic solvent that is insoluble to this etching solution at etching solution surface coverage one deck is as protective seam;
(2) make etching solution temperature constant, the bare fibre that end face is smooth inserts in etching solution, carries out static etching; Described static etching refers in etching reaction process does not do any adjustment to etching solution;
(3) in etching solution, dropwise add adjustment liquid, stir etching solution simultaneously, carry out dynamic etching, adjusting liquid is HF solution or NH
4f solution; Described dynamic etching refer in etching reaction process by add adjust liquid make etching solution in the ratio of each composition change;
(4) stop adding adjustment liquid, stop stirring etching solution, carry out static etching, make optical fiber probe.
Preferably, in described step (3), adjusting liquid is HF solution, and the speed of dripping of adjusting liquid comprises first speed and second speed, adjusts liquid and successively with first speed and second speed, splashes into etching solution respectively, and described first speed is greater than described second speed.
Preferably, in described step (3), adjustment liquid is NH
4f solution, the speed of dripping of adjusting liquid comprises first speed and second speed, adjusts liquid and successively with first speed and second speed, splashes into etching solution respectively, described first speed is less than described second speed.
Preferably, make the temperature constant of etching solution at 28~30 ℃.
In general, the above technical scheme of conceiving by the present invention compared with prior art, has following beneficial effect:
(1) adopt selective etch method, at bare fibre end face, become cone, because end face is immersed in etching solution, etching process is not subject to outside air disturbing influence, the optical fiber probe surface topography of preparation is smooth, under high magnification SEM image, can't see obvious coarse point, carrying out near field optic while measuring, excite and the signal collected can be because of the scattering dissipation excessive power at rough surface place.
(2) in etching process, add adjustment liquid, when dropwise adding HF solution, NH
4the concentration of F declines gradually, and it is large that probe cone angle becomes gradually; When dropwise adding NH
4during F solution, NH
4the concentration of F rises gradually, and probe cone angle diminishes gradually.Therefore the present invention can prepare the probe of various tapers, comprises the nonlinear conical probe that nonlinear conical probe that cone angle reduces from the top to the bottom gradually and cone angle increase from the top to the bottom gradually.
(3) this method does not need accurate equipment and instrument, only needs conventional laboratory room small-sized articles for use to realize, with low cost, and net result can be according to temperature, drip the factors such as speed and regulate, the controllability of technological process is high, can manufacture.
Accompanying drawing explanation
Fig. 1 is the device schematic diagram of preparing optical fiber probe of the embodiment of the present invention;
Fig. 2 is the SEM figure of the optical fiber probe that makes of the embodiment of the present invention 1;
Fig. 3 is the SEM figure of the optical fiber probe that makes of the embodiment of the present invention 2.
In institute's drawings attached, identical Reference numeral is used for representing identical element or structure, wherein: 1-bare fibre, 2-etching solution, 3-adjusts liquid, 4-flow controller, 5-magnetic stirring apparatus, 6-thermometer, 7-stirrer, 8-glass dish.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.In addition,, in each embodiment of described the present invention, involved technical characterictic just can not combine mutually as long as do not form each other conflict.
The optical fiber probe that existing preparation method obtains is linear taper, yet the logical light rate of linear taper probe is restricted, nonlinear conical structure (the vicissitudinous cone angle of tool) can change light-transfer characteristic, improve logical light rate, have broad application prospects.The present invention adds adjustment liquid in etching process, by change, is adjusted the type of liquid and is dripped speed, adjusts the taper of optical fiber probe, prepares the nonlinear conical probe of different shape, is conducive to further further investigate taper and changes the impact on the logical light rate of probe.
The preparation method of the optical fiber probe of the embodiment of the present invention comprises the steps:
(1) by HF solution and NH
4f solution is mixed to get etching solution, and the organic solvent that is insoluble to this etching solution at etching solution surface coverage one deck is as protective seam.
(2) make etching solution temperature constant, the bare fibre that end face is smooth inserts in etching solution, carries out static etching.Static etching refers in etching reaction process does not do any adjustment to etching solution.
(3) in etching solution, dropwise add adjustment liquid, stir etching solution simultaneously, carry out dynamic etching, adjusting liquid is HF solution or NH
4f solution.The dynamic relatively static etching of etching, refer in etching reaction process by add adjust liquid make etching solution in the ratio of each composition change.
When adjustment liquid is HF solution, that adjusts liquid drips speed first quick and back slow; When adjusting liquid, be NH
4during F solution, dripping of adjustment liquid is fast first slow rear fast.
(4) stop adding adjustment liquid, stop stirring etching solution, carry out static etching, make optical fiber probe.
Bare fibre comprises fibre cladding and fibre core, and the principal ingredient of covering is SiO
2, and fibre core is because being mixed with a certain amount of germanium, principal ingredient is SiO
2and GeO
2.When the adjustment liquid adding is NH
4during F solution, NH in etching solution
4the content of F increases gradually, makes the poor increase gradually of etch rate of covering and fibre core, thereby the cone angle of the probe of formation is diminished gradually; When the adjustment liquid adding is HF solution, NH in etching solution
4the content of F reduces gradually, makes that the etch rate of covering and fibre core is poor to be reduced gradually, thereby makes the cone angle of the probe that forms become gradually large.The composition of the adjustment liquid adding by adjustment and a speed, realize the adjustment to probe cone angle.
For making those skilled in the art understand better the present invention, below in conjunction with specific embodiment, the preparation method of optical fiber probe of the present invention is elaborated.
As shown in Figure 1, the device of preparing optical fiber probe of the embodiment of the present invention comprises flow controller 4, magnetic stirring apparatus 5, thermometer 6, stirrer 7 and glass dish 8, glass dish 8 is placed on magnetic stirring apparatus 5, flow controller 4 be positioned at glass dish 8 directly over, thermometer 6 inserts in glass dishes 8.The embodiment of the present invention adopts this device to prepare optical fiber probe.
Embodiment 1
The NH that the HF solution that is 50% by 10ml massfraction and 23ml massfraction are 22%
4the mixing of F solution is made into etching solution, and on etching solution, covers the isooctane that one deck 3cm is thick; Open magnetic stirring apparatus 5, with water-bath, etching solution temperature is controlled to 28 ℃; Optical fiber is inserted in etching solution, carry out the static etching of 60min; The NH that is 40% by massfraction
4f solution injects flow controller 4 as adjusting liquid, stirrer 7 is put into etching solution and start to stir, and opens flow controller valve and allows adjustment drop enter in etching solution, and dripping speed is 0.3ml/min, and the process that splashes into continues 15min; Regulate and drip speed to 1.5ml/min, the process that splashes into continues 15min; Stirrer stops stirring, and keeps existing concentration, carries out the static etching of 10min.
As shown in Figure 2, detecting probe surface is very smooth for the optical fiber probe making, and its cone angle reduces gradually from tips of probes to root, and it is parabola shaped that the shaft section of detecting probe surface is class.This is because added the NH that massfraction is 40% in etching process
4f solution, as adjusting liquid, makes NH
4the content of F in etching solution increases gradually, and the cone angle that forms probe is diminished gradually.In addition, dripping of adjustment liquid is fast first rear fast slowly, and accordingly, the speed that cone angle diminishes is first slow soon rear.
Embodiment 2
The HF solution that is 22% by 20ml massfraction and 19ml massfraction are 40%NH
4the mixing of F solution is made into etching solution, and on etching solution, covers the isooctane that one deck 3cm is thick; Open magnetic stirring apparatus 5, with water-bath, etching solution temperature is controlled to 30 ℃; Optical fiber is inserted in etching solution, carry out the static etching of 20min; The HF solution that is 22% using massfraction injects flow controller 4 as adjusting liquid, stirrer 7 is put into etching solution and start to stir, and opens flow controller valve and allows adjustment drop enter in etching solution, and dripping speed is 1ml/min, and the process that splashes into continues 15min; Regulate and drip speed to 0.3ml/min, the process that splashes into continues 5min; Stirrer stops stirring, and keeps existing concentration, carries out the static etching of 5min.
As shown in Figure 3, detecting probe surface is essentially smooth for the optical fiber probe making, and its cone angle increases gradually from tips of probes to root.This is because added HF solution that massfraction is 22% as adjusting liquid in etching process, makes NH
4the content of F in etching solution gradually, makes the cone angle forming become gradually large.In addition, that adjusts liquid drips speed first quick and back slow, and accordingly, cone angle becomes large speed first quick and back slow.
Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.