TWI467137B - Optical fiber sensors and the manufacturing method thereof - Google Patents

Description

Optical fiber sensor and manufacturing method thereof

The present invention relates to a sensor; and more particularly to a fiber optic sensor and method of fabricating the same.

Please refer to FIG. 1 , which is a schematic diagram of a fiber optic sensor of a conventional whispering gallery mode. The conventional fiber optic sensor 9 first bends an optical fiber 91 and clamps the optical fiber 91 with a clamp 92 to keep the optical fiber 91 in a curved shape for applying the Whispering Gallery Mode. Measure temperature or strain and other uses.

However, since the conventional optical fiber sensor 9 clamps the optical fiber 91 with the above-mentioned jig 92, it is easy to be improperly touched by other objects for the optical fiber 91 during the sensing process, or the jig 92 is used for a long time. The situation of fatigue or looseness causes abnormal changes in the bending diameter or curvature of the optical fiber 91, resulting in a phenomenon of peak drift, which affects the accuracy of the sensing value, and therefore, the sensing sensitivity of the optical fiber sensor 9 is lowered. stability.

According to this, the above-mentioned conventional optical fiber sensor 9 not only has problems such as "abnormally changed bending diameter or curvature" and "tired or loose clamp", but also causes "sensitivity and low stability". When doubts arise, there are many limitations and shortcomings in actual use. There are inconveniences and further improvements are needed to enhance their practicality.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a fiber optic sensor that avoids abnormal deformation of the fiber.

A second object of the present invention is to provide a fiber optic sensor that can secure an optical fiber without the need for a clamp.

Another object of the present invention is to provide a method of fabricating a fiber optic sensor that coats an optical fiber with a metal such that the metal can fix the shape of the optical fiber.

The optical fiber sensor of the present invention comprises: an optical fiber having a first curved portion; and a cladding layer having a second curved portion covering the first curved portion of the optical fiber, the cladding layer being ceramic Composition.

Preferably, the optical fiber sensor of the present invention further comprises a metal connecting member coupled to the two ends of the covering layer.

Preferably, the optical fiber has two end portions, and the two end portions are bent to form the first curved portion, and the two end portions extend in parallel in the same direction.

Preferably, the optical fiber has two end portions, and the two end portions are bent to form the first curved portion, and the two end portions extend non-parallel in the same quadrant direction.

Preferably, the curvature of the first curved portion is substantially the same as the curvature of the second curved portion.

Preferably, the two ends of the cladding layer extend to both ends of the optical fiber.

The method for manufacturing a fiber optic sensor of the present invention comprises: plating a metal layer on a surface of a wafer; coating a substrate layer on the metal layer, and forming at least one microchannel structure on a surface of the substrate layer; The microchannel structure has an arc channel and two through holes; an optical fiber is built in the microchannel structure, and a cladding layer is electroformed on the outer surface of the fiber; and the metal layer and the substrate layer are removed; Wherein, the metal layer is electrically connected to a conductive plate of an electroforming groove, and the conductive plate is placed in a plating solution, and an anode of the electroforming groove is provided with an electroforming material, and a cathode of the electroforming groove is electrically connected to the metal layer An electroforming operation is performed between the anode and the cathode, and the plating solution and the electroforming material both contain nickel.

Preferably, the micro flow channel structure is provided with a connecting channel, and the connecting channel connects the two Through hole.

Preferably, the micro flow channel structure is formed on the upper surface of the substrate layer by an etching technique.

Preferably, the microchannel structure is formed on the upper surface of the substrate layer by engraving techniques.

Preferably, the two through holes extend outward in the radial direction of the wafer.

Preferably, the two through holes extend in parallel in the same direction.

Preferably, the two through holes extend non-parallel in the same quadrant direction.

Preferably, the optical fiber is bent to form a first curved portion, and the first curved portion is fitted to the arc passage, and the curved curvature of the first curved portion is substantially the same as the curved curvature of the arc passage.

Preferably, the optical fiber has two ends, and the two ends protrude from the two through holes of the micro flow channel structure.

Preferably, the cladding layer is made of metal.

〔this invention〕

1‧‧‧Fiber

11‧‧‧First bend

12, 12a, 12b‧‧‧ end

2‧‧‧envement

21‧‧‧second bend

3‧‧‧Metal joints

A‧‧‧ arc channel

B‧‧‧Substrate area

C‧‧‧ relationship curve

E‧‧‧through hole

M‧‧‧ metal layer

N‧‧‧non-etched area

R‧‧‧ substrate layer

T‧‧‧microchannel structure

W‧‧‧ wafer

R‧‧‧bend radius

[study]

9‧‧‧Learning fiber optic sensor

91‧‧‧Fiber

92‧‧‧ fixture

Figure 1 is a schematic view of the structure of a conventional fiber optic sensor.

Figure 2 is a combined perspective view of a preferred embodiment of the fiber optic sensor of the present invention.

Figure 3a is a schematic view of the fiber extending direction of the preferred embodiment of the fiber optic sensor of the present invention.

Figure 3b is a schematic view of a metal joint of a preferred embodiment of the fiber optic sensor of the present invention.

Fig. 4 is a flow chart showing a preferred embodiment of the method of manufacturing the optical fiber sensor of the present invention.

Fig. 5 is a schematic view showing the manufacturing process of the preferred embodiment of the method for fabricating the optical fiber sensor of the present invention.

Fig. 6a is an enlarged view of (d) of Fig. 5.

Figure 6b is an enlarged view of (e) of Figure 5.

Fig. 6c is an enlarged view of (f) of Fig. 5.

Figure 7a is a graph (I) of the relationship between the optical fiber sensor of the present invention and the temperature measurement.

Figure 7b is a graph (2) of the relationship between the optical fiber sensor of the present invention and the temperature measurement.

The above and other objects, features and advantages of the present invention will become more <RTIgt; It is a combined perspective view of a preferred embodiment of the optical fiber sensor of the present invention. The optical fiber sensor comprises an optical fiber 1 and a cladding layer 2, the optical fiber 1 is bent and formed, and the cladding layer 2 surrounds the optical fiber 1. The outer peripheral surface allows the optical fiber 1 to remain curved. The fiber optic sensor can be an echo modal modal fiber optic sensor.

The optical fiber 1 can be made of a conventional optical fiber material. The optical fiber 1 is provided with a first curved portion 11 and two end portions 12, and the two curved ends 11 are bent to form the first curved portion 11. The parallel direction extends in the same direction (as shown in FIG. 2), so that the optical fiber 1 is formed in a U shape, and the two end portions 12 can also extend non-parallel in the same quadrant direction (as shown in FIG. 3a), and can be used to adjust the center. The range of wavelengths used. In this embodiment, the optical fiber 1 is in the form of a single-mode optical fiber having a diameter of 75 micrometers (μm), and the two end portions 12a, 12b extend in the same direction to bend the first curved portion 11. A suitable bending radius or bending curvature, wherein, as shown in FIG. 2, the bending radius r may be 3 to 7 millimeters (mm), but not limited thereto.

The cladding layer 2 is coated on the outer peripheral surface of the optical fiber 1 for fixing the shape of the optical fiber 1. The cladding layer 2 has a second curved portion 21 covering the first curved portion 11 of the optical fiber 1. The first curved portion 11 is not easily deformed by being touched by other objects, so as to be used as a strain sensing. The cladding layer 2 may be made of a tough material, such as a metal, etc., preferably a metal material having toughness, magnetic properties, plasticity, and non-oxidation, such as nickel (Ni) metal or alloy thereof. The cladding layer 2 can also be doped with a metal material having a high coefficient of thermal expansion. For example, aluminum (Al), lead (Pb) or tin (Sn), etc., such that the cladding layer 2 can be thermally expanded and contracted with temperature to change the bending radius of the first bent portion 11 of the optical fiber 1 or The curvature is used for temperature sensing; in addition, the cladding layer 2 may also be made of a ceramic or the like to strengthen the shaping effect of the optical fiber 1 for strain sensing. In this embodiment, the cladding layer 2 is made of nickel metal, wherein the bending curvature of the second bending portion 21 is substantially the same as the bending curvature of the first bending portion 11, the covering layer. The second end of the optical fiber 1 is preferably extended to the two ends 12a and 12b of the optical fiber 1 so that the first bending portion 11 can be fixed to the covering layer 2, but not limited thereto.

In order to improve the temperature sensing effect of the optical fiber sensor, a preferred embodiment of the present invention may further provide a metal connecting member 3 (as shown in FIG. 3b) for bonding the above-mentioned covering layer. The two opposite portions of the second portion, for example, the two ends of the cladding layer 2, can further improve the sensitivity of the first curved portion 11 to temperature sensing. The metal connecting member 3 and the covering layer 2 can be integrally formed, bonded, locked or sheathed, so that the metal connecting member 3 is surely coupled to the opposite ends of the covering layer 2. In this embodiment, the metal connecting member 3 is metal-bonded to the two ends of the covering layer 2, but not limited thereto.

Please refer to FIG. 4, which is a flow chart of a preferred embodiment of the method for fabricating the optical fiber sensor of the present invention. The manufacturing method of the optical fiber sensor includes a plurality of steps S1 to S4, which are respectively described later. Please refer to FIG. 5, which is a schematic diagram of a manufacturing process of a preferred embodiment of the method for fabricating the optical fiber sensor of the present invention.

In the above step S1, a metal layer is plated on the surface of a wafer. In detail, as shown in (a) of FIG. 5, the wafer W is first prepared, for example, a germanium (Si) wafer, which may be subjected to a cleaning process (eg, a heat treatment procedure). To remove surface contamination, then, as shown in FIG. 5(b), the metal layer M is formed on the surface of the wafer W by electroplating, for example, a copper (Cu) layer or the like for use as a conductive layer. .

Referring to FIG. 4 again, the above step S2 is performed on the above metal layer coating. A substrate layer is formed on the surface of the substrate layer to form at least one microchannel structure, the microchannel structure having an arc channel and two through holes. In particular, the microchannel structure can be fabricated using photolithography etching or sheet carving techniques. Taking the yellow light lithography process as an example, as shown in FIG. 5(c), a photoresist material may be coated on the metal layer M by a spin coater, and then passed through a heating furnace. Soft bake is performed to volatilize the organic solvent in the photoresist material to change the photoresist material from a liquid state to a solid substrate layer R. Next, the base layer R is exposed by ultraviolet light (UV) to cause a chain reaction of the polymer. As a result, as shown in FIGS. 5(d) and 6a, the non-etched regions N in the plurality of substrate regions B of the substrate layer R will be stronger. After the exposure operation is completed, a post-exposure bake (PEB) and development (Development) operation is performed to form the micro-channel structure T, the micro-channel structure T having the arc channel A and the two-way hole E, The optical fiber 1 is received and the cladding layer 2 is formed. In this embodiment, the number of the micro-channel structure T and the number of the optical fibers 1 are several, but not limited thereto; wherein the micro-channel structure T-etching is formed in the a surface of the substrate layer R; the two via holes E may extend in parallel in the same direction or non-parallel in the same quadrant direction, and the two via holes E preferably extend outward in the radial direction of the wafer W, avoiding the The plurality of optical fibers 1 interfere with each other; in addition, the micro-channel structure T may further be provided with a connecting passage (not shown) connecting the two through holes E for forming the metal connecting member 3, which is well known to the skilled person. It can be understood that it will not be described here. Thereafter, the wafer W is preferably rotated at a high speed by a spin coater to dry the developer remaining in the developing operation. In addition, if the microchannel structure T is formed by a plate engraving process, the microchannel structure T can be formed by engraving on the surface of the substrate layer R by an engraving machine.

Referring to FIG. 4 again, in the above step S3, an optical fiber is built in the micro flow channel structure, and a cladding layer is electroformed on the outer surface of the optical fiber. In detail, as shown in FIG. 5(e) and FIG. 6b, when the optical fiber 1 is placed in the microchannel structure T, the first curved portion 11 of the optical fiber 1 is fitted to the arc channel A, and the first a curved curvature of a curved portion 11 and the arc passage The bending curvature of A is preferably substantially the same to improve the adhesion of the cladding layer 2 to the optical fiber 1. The two end portions 12 of the optical fiber 1 preferably protrude from the two-hole E of the micro-channel structure T, so that The cladding layer 2 can be fixed to the first bending portion 11; then, the metal layer is electrically connected to a conductive plate (not shown) of the electroforming groove, and the conductive plate is placed in a plating solution. For example, a plating solution containing an electroforming material (such as nickel); then, the electroforming material (such as a nickel cake) is placed on the anode of the electroforming tank, and the cathode of the electroforming tank is electrically connected to the cathode a metal layer; thereafter, an electroforming process can be performed between the anode and the cathode until the outer surface of the optical fiber 1 is formed of the electroforming material (eg, nickel) to form the cladding layer 2 of a suitable thickness (eg, Figure 5 (f) and Figure 6c), for example, if nickel is used as the electroforming material, a current of 0.25 amps (A) is applied to the electroforming cell for about 3 hours, and the thickness of the cladding layer 2 is The manner of adjusting the plating time according to different electroforming materials can be up to about 150 micrometers, which can be understood by those skilled in the art, and will not be described herein. In this embodiment, the encapsulation layer 2 is formed by using nickel as an embodiment. The components of the electroplating solution and the electroforming operation conditions are respectively shown in the following Tables 1 and 2, but limit.

It can be seen from Tables 1 and 2 above that the nickel sulfonate can be used to assist the dissociation of the electroforming material, and the preferred concentration is 450 g/l, which can improve the flattening effect of the above-mentioned coating layer 2; The anode is dissolved and the conductivity is increased. The preferred concentration is 3~5g/l, which avoids the reduction of the gloss agent and reduces the softness. In addition, boric acid can be used as an acid-base buffer to maintain the adhesion and ductility of the cladding layer 2. In addition, the bath temperature is preferably 42 to 45 ° C, which can increase the current density to increase the thickness of the cladding layer 2 and reduce the stress; further, the pH value is preferably 4.0 g / l, in order to avoid the inclusion The flatness and softness of layer 2 are too low.

In the above step S4, the metal layer M and the base material layer R are removed. In detail, as shown in FIG. 5(f) and FIG. 6c, after the outer cladding surface of the optical fiber 1 is formed with the cladding layer 2, the wafer W can be immersed in an etching solution (eg, hydrogen peroxide). a solution in which ammonia and deionized water are mixed to etch the metal layer M, and as shown in FIGS. 5(f) and (g), the substrate region B of the substrate layer R is separated from the wafer. W. Then, the substrate layer R is further immersed in the photoresist removal liquid, and the photoresist removal liquid is preferably heated to 50 ° C to accelerate the removal speed of the photoresist material until the photoresist of the substrate layer R A preferred embodiment of the fiber optic sensor of the present invention (as shown in Figure 5(h)) is obtained by completely removing the material.

In a preferred embodiment of the optical fiber sensor of the present invention, the optical fiber sensor can be attached to an object to be tested (for example, a moving object or a heat generating object, etc.), and then one end of the optical fiber 1 can be Connected to a broadband light source via a light circulator, and the other end of the optical fiber 1 can be strung between the optical circulator and the optical circulator Connected to a light filter, a photoelectric converter (PD) and a data acquisition system (DAQ), the data acquisition system can be electrically connected to a computer.

Thereby, the broadband light source can transmit a light source to the fiber optic sensor, and the light wave outputted by the fiber optic sensor can pass through the optical filter, the photoelectric converter and the data capture system, and finally, the light wave is recorded by the computer. wavelength. At the same time, the computer can store a graph/table of the relationship between the wavelength and different physical quantities.

When the physical quantity of the object to be tested changes, for example, the optical fiber 1 vibrates due to the movement of the object to be tested; or the temperature of the object to be tested changes, causing the cladding layer 2 to heat up and shrink, causing the fiber to be caused. 1 deformation, the bending radius or curvature of the first curved portion 11 of the optical fiber 1 will change, and the wavelength of the light wave recorded by the computer is changed, and the wavelength of the light wave and the relationship graph/table are obtained. Know the physical quantity change of the analyte. The following is an example of temperature sensing, but not limited to this.

Please refer to Figures 7a and 7b, which are diagrams (1) and (2) of the optical fiber sensor of the present invention used for temperature sensing. It can be seen from Fig. 7a that the fiber optic sensor has different interference spectrum changes under different temperature changes. When the object to be tested is warmed, the interference spectrum of the fiber sensor will drift from right to left, at temperature. The maximum interference loss is -61.66 (dBm) for 30 (°C) and the wavelength value is 1551.75 (nm); when the temperature is raised from 30 (°C) to 180 (°C), the wavelength value will gradually decrease. Therefore, as can be seen from FIG. 7b, the optical fiber sensor has different wavelength value changes under different temperature changes. When the average temperature rise temperature of the object to be tested is 10.0 (° C.), the average wavelength change is 5.706 (nm). And the linearity (R ² ) is 0.993, and the temperature sensitivity is 0.566 (nm/° C.) at the time of temperature rise; therefore, the wavelength versus temperature C can be expressed as Y=−0.566*X+1564.898, and The linearity of the relationship curve C is 0.993. Similarly, it can be known that the optical fiber sensor of the present invention is applied to the relationship between the strain amount and the wavelength when the strain amount is changed, and is used as the strain measuring application of the object to be tested. By analogy, the fiber optic sensor of the present invention can be applied to sensing applications of other physical quantities.

The main features of the preferred embodiment of the optical fiber sensor of the present invention are as follows: the above-mentioned cladding layer 2 is formed by a hard and opaque material, and the cladding layer 2 covers the optical fiber. At 1 o'clock, it can be ensured that the first curved portion 11 of the optical fiber 1 forms an appropriate bending radius or curvature, and the bending radius or the curvature of the first curved portion 11 can be stably maintained without using a clamp to fix the first bending portion. 11 is not easily deformed by other objects, and the deformation effect of the first bending portion 11 is further stabilized, thereby achieving the effect of "improving the sensing stability". In addition, the cladding layer 2 can be further doped with a metal material having a higher coefficient of thermal expansion, so that the cladding layer 2 can be thermally expanded and contracted with temperature to change the bending radius or curvature of the first bending portion 11 . For the purpose of temperature sensing, the cladding layer 2 can further be provided with the metal connecting member 3 to achieve the effect of "improving sensing sensitivity". Moreover, if the optical fiber sensor of the present invention is combined with the above-mentioned broadband light source, optical circulator, photoelectric converter, data acquisition system, computer, etc., the physical quantity sensed by the optical fiber sensor can be easily interpreted.

In the preferred embodiment of the method of manufacturing the optical fiber sensor of the present invention, the metal covering the optical fiber 1 can be formed by only electroforming, which is not only "easy to manufacture" but also "low in manufacturing cost".

The optical fiber sensor of the present invention coats the optical fiber with a tough material (such as metal or ceramics), stably maintains the shape of the optical fiber, and achieves the effect of "avoiding abnormal deformation of the optical fiber".

The optical fiber sensor of the present invention coats the optical fiber with a tough material, stably maintains the shape of the optical fiber, and achieves the effect of "fixing the optical fiber without using a jig".

In the method for manufacturing the optical fiber sensor of the present invention, the metal covering the optical fiber is formed by electroforming to fix the shape of the optical fiber, thereby achieving the functions of "easy production" and "low cost".

1‧‧‧Fiber

11‧‧‧First bend

12, 12a, 12b‧‧‧ end

2‧‧‧envement

21‧‧‧second bend

R‧‧‧bend radius

Claims (16)

A fiber optic sensor comprising: an optical fiber having a first bent portion; and a clad layer having a second bent portion covering the first bent portion of the optical fiber, the clad layer being composed of ceramic. The optical fiber sensor according to claim 1 of the patent application, further comprising a metal connecting member coupled to the two ends of the covering layer. The optical fiber sensor according to claim 1 or 2, wherein the optical fiber has two end portions, and the two end portions are bent to form the first curved portion, and the two end portions extend in parallel in the same direction. A fiber optic sensor according to claim 1 or 2, wherein the optical fiber has two ends, and the two end portions are bent to form the first curved portion, and the two end portions extend non-parallel in the same quadrant direction. The optical fiber sensor according to claim 1, wherein the bending curvature of the first curved portion is substantially the same as the bending curvature of the second curved portion. The optical fiber sensor of claim 1, wherein the two ends of the cladding layer extend to both ends of the optical fiber. A method for manufacturing a fiber optic sensor includes: plating a metal layer on a surface of a wafer; coating a substrate layer on the metal layer; forming at least one microchannel structure on a surface of the substrate layer, the micro The flow channel structure has an arc channel and a second through hole; a fiber is built in the microchannel structure, and a cladding layer is electroformed on the outer surface of the fiber; and the metal layer and the substrate layer are removed; The metal layer is electrically connected to a conductive plate of an electroforming groove, and the conductive plate is placed on an electric plate In the plating solution, an anode of the electroforming tank is provided with an electroforming material, and a cathode of the electroforming tank is electrically connected to the metal layer, and an electroforming operation is performed between the anode and the cathode, and the plating solution and the electroforming material are Both contain nickel. According to the manufacturing method of the optical fiber sensor of claim 7, wherein the micro flow path structure is provided with a connecting passage connecting the two through holes. A method of fabricating a fiber optic sensor according to claim 7 or 8, wherein the microchannel structure is etched on an upper surface of the substrate layer. A method of manufacturing a fiber optic sensor according to claim 7 or 8, wherein the microchannel structure is engraved on an upper surface of the substrate layer. A method of fabricating a fiber optic sensor according to claim 7 or 8, wherein the two through holes extend outward in a radial direction of the wafer. A method of manufacturing a fiber optic sensor according to claim 7 or 8, wherein the two through holes extend in parallel in the same direction. A method of manufacturing a fiber optic sensor according to claim 7 or 8, wherein the two through holes extend non-parallel in the same quadrant direction. A method of manufacturing a fiber optic sensor according to claim 7 or 8, wherein the optical fiber is bent to form a first curved portion, the first curved portion is fitted to the arc passage, and the bending curvature of the first curved portion is The curvature of the arc channel is substantially the same. The optical fiber sensor manufacturing method according to claim 7 or 8, wherein the optical fiber has two ends, and the two end portions protrude from the two through holes of the micro flow path structure. A method of manufacturing a fiber optic sensor according to claim 7 or 8, wherein the cladding layer is made of a metal.