Optical fiber device for removing cladding light, apparatus and method for etching the same

The present invention relates to an optical fiber device for removing cladding light, an apparatus and a method for etching the same. The optical fiber device comprises: a first optical fiber section through an Nth optical fiber section arranged in sequence along a light travelling direction; and a first tapered coupling section coupling a Kth optical fiber section and a (K+1)th optical fiber section, where the Kth optical fiber section is any one of the first optical fiber section through the Nth optical fiber section and the (K+1)th optical fiber section is any one of the first optical fiber section through the Nth optical fiber section adjacent to the Kth optical fiber section, wherein the Kth optical fiber section comprises: at least one first subsection and at least one second subsection alternately arranged along the light travelling direction, each of the at least one first subsection having a diameter D2K−1 and a length L2K−1; and each of the at least one second subsection having a diameter D2K and a length L2K; and a second tapered coupling section coupling the first subsection and the second subsection adjacent to the first subsection, wherein the diameter D2K−1 and the length L2K−1 of the first subsection and the diameter D2K and the length L2K of the second subsection of the Kth optical fiber section and a diameter D2K+1 and a length L2K+1 of the first subsection and a diameter D2K+2 and a length L2K+2 of the second subsection of the (K+1)th optical fiber section satisfy D2K−1>D2K, D2K+1>D2K+2, L2K−1>L2K+1, L2K>L2K+2 and D2K−1=D2K+1, and satisfy D2K>D2K+2 for odd K and D2K<D2K+2 for even K (where N is a natural number, and K is any natural number satisfying 1≤K≤N−1).

This non-provisional U.S. patent application claims priority under 35 U.S.C. § 119 of Korean Patent Applications No. 10-2020-0037755 filed on Mar. 27, 2020 and No. 10-2020-0078587 filed on Jun. 26, 2020, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference.

The present invention relates to an optical fiber device for removing cladding light, an apparatus and a method for etching the same, and more particularly, to an optical fiber device capable of efficiently releasing excessive cladding light, apparatus and method for etching the same.

2. DESCRIPTION OF THE RELATED ART

Conventionally, a solid state laser was used to embody a high power laser beam generator. More recently, an optical fiber is used to embody a high power laser beam generator.

A high power laser beam generator employing an optical fiber has the following advantages over solid state lasers.

First, since the optical fiber has a diameter of several hundred micrometers, it is possible to implement a high power laser beam generator with a small footprint compared to a solid state laser.

In the case of optical fibers, the gain medium may be elongated, thereby increasing surface area in contact with air per unit active volume. Therefore, heat dissipation and cooling are facilitated compared to solid state lasers. Due to this characteristic, optical fiber lasers are receiving more attention than high-power lasers which have limited high outputs due to difficulty in heat dissipation.

In addition, since optical fibers are much thinner and more flexible than solid state lasers, optical fibers are spatially advantageous when used in high power lasers. Moreover, solid state laser device is disadvantageous in that alignment, which is achieved using a lens, may easily be lost due to external shock. On the other hand, in the case of optical fiber laser, it is possible to implement laser without alignment, providing the advantage of high structural stability and portability.

Lastly, optical fiber lasers can produce high-quality beams even at high power compared to solid state lasers. By using these characteristics, a more sophisticated and effective high-power laser may be obtained.

FIG.1is a cross-sectional view illustrating a conventional optical fiber device and propagation of light therein.

Referring toFIG.1, a conventional optical fiber (double-clad fiber) includes a core20which constitutes a path of signal beam, an inner cladding30surrounding the core20which is path of a pump beam, and an outer cladding40surrounding the inner cladding30.

The pump beam is totally reflected at the boundary of the inner cladding30and the outer cladding40and amplifies the signal beam traveling along the core20.

The pump beam remaining after amplifying the signal beam must be removed at the output stage of the laser generating device. In addition, lights leaking from the connection part (spliced part) of the optical fiber and the core20as well as the remaining pump beam must be removed.

A device that removes such extra light is called a cladding light stripper (CLS). When the extra light is not removed, the extra light may not only interfere with propagation of light but also cause damage to the optical fiber due to heat. Thus, the extra light must be removed.

Therefore, CLS, which is capable of removing extra light with high efficiency, is essential to manufacturing a high power laser beam generator using optical fiber.

Various methods have been proposed to manufacture CLS. A typical method of manufacturing CLS is by regularly etching the surface of an optical fiber device into a lattice.

Specifically, a method of manufacturing a optical fiber device by etching the surface of an optical fiber with a UV laser or a CO2laser or chemically etching has been proposed in Korean Patent No. 10-1139632.

The method of using a UV laser or CO2laser is disadvantageous because the method requires highly priced equipments while the method of chemically etching the surface of an optical fiber is disadvantageous in that it is difficult to control the degree of etching, and in particular, it is difficult to control the spacing of the lattice.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an optical fiber device for removing cladding light and an apparatus and a method for etching the same capable of efficiently releasing excessive cladding light.

According to one aspect of the present invention, there is provided an optical fiber device for removing cladding light, comprising: a first optical fiber section through an Nthoptical fiber section arranged in sequence along a light travelling direction; and a first tapered coupling section coupling a Kthoptical fiber section and a (K+1)thoptical fiber section, where the Kthoptical fiber section is any one of the first optical fiber section through the Nthoptical fiber section and the (K+1)thoptical fiber section is any one of the first optical fiber section through the Nthoptical fiber section adjacent to the Kthoptical fiber section, wherein the Kthoptical fiber section comprises: at least one first subsection and at least one second subsection alternately arranged along the light travelling direction, each of the at least one first subsection having a diameter D2K−1and a length L2K−1; and each of the at least one second subsection having a diameter D2Kand a length L2K; and a second tapered coupling section coupling the first subsection and the second subsection adjacent to the first subsection, wherein the diameter D2K−1and the length L2K−1of the first subsection and the diameter D2Kand the length L2Kof the second subsection of the Kthoptical fiber section and a diameter D2K+1and a length L2K+1of the first subsection and a diameter D2K+2and a length L2K+2of the second subsection of the (K+1)thoptical fiber section satisfy D2K−1>D2K, D2K+1>D2K+2, L2K−1>L2K+1, L2K>L2K+2and D2K−1=D2K+1, and satisfy D2K>D2K+2for odd K and D2K<D2K+2for even K (where N is a natural number, and K is any natural number satisfying 1≤K≤N−1).

It is preferable that L2K−1<L2Kis satisfied for any K.

It is preferable that L2K+1<L2K+2is satisfied for any K.

Preferably, N is four, and the first optical fiber section is coupled to a second optical fiber section by the first tapered coupling section, the second optical fiber section is coupled to a third optical fiber section by the first tapered coupling section, and the third optical fiber section is coupled to a fourth optical fiber section by the first tapered coupling section, each of the first optical fiber section through the fourth optical fiber section comprising: the first subsection and the second subsection arranged in sequence along the light travelling direction; and the second tapered coupling section coupling the first subsection and the second subsection of each of the first optical fiber section through the fourth optical fiber section, wherein diameters D1, D3, D5and D7and lengths L1, L3, L5and L7of the first subsections and diameters D2, D4, D6and D8and lengths L2, L4, L6and L8of the second subsections of the first optical fiber section through fourth optical fiber section, respectively, satisfy L1>L3>L5>L6, L2>L4>L6>L8, L1<L2, L3<L4, L5<L6, L7<L8, D1=D3=D5=D7and D2=D6>D4=D8.

Preferably, N is four, and the first optical fiber section is coupled to a second optical fiber section by the first tapered coupling section, the second optical fiber section is coupled to a third optical fiber section by the first tapered coupling section, and the third optical fiber section is coupled to a fourth optical fiber section by the first tapered coupling section, each of the first optical fiber section through the fourth optical fiber section comprising: two first subsection and two second subsection arranged in sequence of first subsection, second subsection, first subsection and second subsection along the light travelling direction; and three second tapered coupling section coupling the first subsection to the second subsection, the second subsection to the first subsection, and the first subsection to the second subsection in each of the first optical fiber section through the fourth optical fiber section, wherein diameters D1, D3, D5and D7and lengths L1, L3, L5and L7of the first subsections and diameters D2, D4, D6and D8and lengths L2, L4, L6and L8of the second subsections of the first optical fiber section through fourth optical fiber section, respectively, satisfy L1>L3>L5>L6, L2>L4>L6>L8, L1<L2, L3<L4, L5<L6, L7<L8, D1=D3=D5=D7and D2=D6>D4=D8.

According to another aspect of the present invention, there is provided an apparatus for etching an optical fiber device, comprising: a main body having a first side and a second side opposite to the first side; two or more etching agent inlets for injecting an etching agent, wherein the two or more etching agent inlets are provided at the first side of the main body; two or more etching agent tanks connected to the two or more etching agent inlets, respectively, wherein the two or more etching agent tanks are provided inside the main body; an isolation plate isolating two neighboring etching agent tank of the two or more etching agent tanks; and two or more etching units connected to the two or more etching agent tanks and isolated by the isolation plate, wherein the two or more etching units are provided at the second side of the main body, wherein each of the two or more etching units comprises: one or more etch baths filled by the etching agent injected through each of the two or more etching agent inlets, wherein one or more etch baths are provided with a distance therebetween; and a groove where the optical fiber device is placed to be in contact with the etching agent in the one or more etch baths, wherein the groove is provided at an edge of each of the one or more etch baths.

Preferably, the two or more etching agent inlets is provided at a first height, and the two or more etching units is provided at a second height lower than the first height.

Preferably, two neighboring etching agent inlets of the two or more etching agent inlets are isolated by the isolation plate.

Preferably, each of the one or more etch baths is provided at a height so as to be filled with the etching agent when each of the two or more etching agent tanks is filled with the etching agent.

Preferably, the one or more etch baths of a first one of the two or more etching units are spaced apart by a first distance, the one or more etch baths of a second one of the two or more etching units neighboring the first one of the two or more etching units are spaced apart by a second distance different from the first distance.

According to yet another aspect of the present invention, there is provided method for etching an optical fiber device using an apparatus for etching the optical fiber device comprising: two or more etching agent inlets for injecting an etching agent; two or more etching agent tanks connected to the two or more etching agent inlets, respectively; an isolation plate isolating two neighboring etching agent tank of the two or more etching agent tanks; and two or more etching units connected to the two or more etching agent tanks and isolated by the isolation plate, wherein each of the two or more etching units comprises: one or more etch baths with a distance therebetween filled by the etching agent injected through each of the two or more etching agent inlets; and a groove where the optical fiber device is placed to be in contact with the etching agent in the one or more etch baths, wherein the groove is provided at an edge of each of the one or more etch baths, the method comprising: (a) placing the optical fiber device in the groove; (b) injecting the etching agent into each of the two or more etching agent inlets with a time difference therebetween; (c) etching the optical fiber device wherein time durations of etching portions of the optical fiber device by the etching agent differ depending on the time difference for each of the two or more etching units; and (d) removing etched optical fiber device from the apparatus.

Preferably, (b) comprises: (b-1) injecting the etching agent into a first one of the two or more etching agent inlets connected to the etching unit provided with the one or more etch baths having a first spacing therebetween; and (b-2) then injecting the etching agent into a second one of the two or more etching agent inlets connected to the etching unit provided with the one or more etch baths having a second spacing therebetween, the second spacing being smaller than the first spacing.

Preferably, (c) comprises: (c-1) etching a first portion of the optical fiber device placed in the grove of the etching unit provided with the one or more etch baths having the first spacing therebetween for a first time duration; and (c-2) etching a second portion of the optical fiber device placed in the grove of the etching unit provided with the one or more etch baths having the second spacing therebetween for a second time duration shorter than the first time duration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an optical fiber device for removing cladding light, apparatus and method for etching the same will be described in detail with reference to the accompanying drawings.

FIG.2is a cross-sectional view schematically illustrating an optical fiber device for removing cladding light according to the present invention. WhileFIG.2shows an optical fiber device divided into upper and lower parts, this is to facilitate the illustration of an elongated optical fiber device, and the optical fiber device according to the present invention is actually connected as a single piece and has no disconnected part. The same is true for the optical fiber device for removing cladding light shown inFIGS.3and4. In addition, in the Specification, the term “first optical fiber section”, “second optical fiber section”, “first section”, “second section” and “tapered coupling section” are conceptually distinguished elements rather than physically distinguished elements.

Referring toFIG.2, the optical fiber device1000for removing cladding light according to the present invention includes a first optical fiber section (abbreviated as “OFS” inFIG.2) through an Nthoptical fiber section arranged in sequence along a light travelling direction denoted by arrow and “LIGHT” thereunder (where N is natural number), and first tapered coupling sections250coupling any two neighboring optical fiber sections of the first optical fiber section through the Nthoptical fiber section.

Specifically, the optical fiber device1000for removing cladding light according to the present invention includes a first optical fiber section onto which light is incident, a second optical fiber section connected to the first optical fiber section, . . . , and an Nthoptical fiber section connected to the (N−1)thoptical fiber section. In addition, two adjacent optical fiber sections are connected via a first tapered coupling section250. For example, the first optical fiber section and the second optical fiber section are connected via the first tapered coupling section250, and the (N−1)thoptical fiber section and the Nthoptical fiber section are connected via the first tapered coupling section250. (N−1) counts of first tapered coupling sections250are provided to connect N counts of optical fiber sections.

Each of the first optical fiber section through the Nthoptical fiber section includes a first subsection (abbreviated as “SS” inFIG.2) and a second subsection. The first subsection and the second subsection are alternately arranged along the light travelling direction. For example, n counts of first subsection and n counts of second subsection are arranged in the order of first subsection, second subsection, . . . , first subsection, second subsection (where n is a natural number).

Each of the first optical fiber section through the Nthoptical fiber section includes one or more second tapered coupling sections150coupling the first subsection and the second subsection. For example, as shown inFIG.2, neighboring first subsection and second subsection are coupled via a second tapered coupling section150, and neighboring second subsection and first subsection are coupled via another second tapered coupling section150. Accordingly, (2n−1) counts of second tapered coupling sections150are provided to couple n counts of first subsections and n counts of second subsections.

Hereinafter, the first subsection and the second subsection will be described in more detail.

Hereinafter, as shown inFIG.2, any one of the first optical fiber section through the Nthoptical fiber section will be referred to as a Kthoptical fiber section, and an optical fiber section adjacent to the Kthoptical fiber section will be referred to as a (K+1)thoptical fiber section (where K is a natural number satisfying 1≤K≤N). Also as shown inFIG.2, the first subsection of the Kthoptical fiber section has a diameter D2K−1and a length L2K−1, and the second subsection of the Kthoptical fiber section has a diameter D2Kand a length L2K. Similarly, the first subsection of the (K+1)thoptical fiber section has diameter D2K+1and length L2K+1, and the second subsection of the (K+1)thoptical fiber section has diameter D2K+2and length L2K+2.

For example, as shown inFIG.2, when K=1, the first subsection of the first optical fiber section has diameter D1and length L1, and the second subsection of the first optical fiber section has diameter D2and length L2. Similarly, the first subsection of the second optical fiber section adjacent to the first optical fiber section has a diameter D3and a length L3, and the second subsection of the second optical fiber section has a diameter D4and a length L4.

When K=2, the first subsection of the second optical fiber section has diameter D3and length L3, and the second subsection of the second optical fiber section has diameter D4and length L4. Similarly, the first subsection of the third optical fiber section adjacent to the second optical fiber section has a diameter D5and a length L5, and the second subsection of the third optical fiber section has a diameter D6and a length L6.

When K=3, the first subsection of the third optical fiber section has diameter D3and length L3, and the second subsection of the third optical fiber section has diameter D6and length L6. Similarly, the first subsection of the fourth optical fiber section adjacent to the third optical fiber section has a diameter D7and a length L7, and the second subsection of the fourth optical fiber section has a diameter D8and a length L8.

The inventors of the present invention designed the first and second subsections of the Kthoptical fiber section and the first and second subsections of the (K+1)thoptical fiber section as follows.

(1) The Diameters and the Lengths of the First Subsections

The diameter of the first subsection is constant regardless of K. That is, D2K−1is equal to D2K+1(i.e. D2K−1=D2K+1) for any K (e.g. D1=D3=D5=D7= . . . )

The length L2K−1of the first subsection of the Kthoptical fiber section is longer than the length L2K+1of the first subsection of the (K+1)thoptical fiber section. That is, L2K−1is greater than L2K+1(i.e. L2K−1>L2K+1) for any K (e.g. L1>L3>L5>L7> . . . ).

(2) The Diameters and Lengths of the Second Subsections

The diameters of the second subsections vary according to K.

Specifically, when K is an odd number, the diameter D2Kof the second subsection of the Kthoptical fiber section is larger than the diameter D2K+2of the second subsection of the (K+1)thoptical fiber section. That is, D2Kis greater than D2K+2(i.e. D2K>D2K+2) for odd number K. For example, when K=1, D2is greater than D4(i.e. D2>D4), and when K=3, D6is greater than D8(i.e. D6>D8).

When K is an even number, the diameter D2Kof the second subsection of the Kthoptical fiber section is smaller than the diameter D2K+2of the second subsection of the (K+1)thoptical fiber section. That is, D2Kis smaller than D2K+2(i.e. D2K<D2K+2) for even number K. For example, when K=2, D4is smaller than D6(i.e. D4<D6), and when K=4, D8is smaller than D10(i.e. D8<D10).

According to such configuration, the diameters of the second subsection are repeated to be “large”, “small”, “large”, “small” . . . as K increases. For example, diameters D2, D4, D6and D8of the second subsection may be 95 um, 90 um, 95 um and 90 um, respectively.

The length L2Kof the second subsection of the Kthoptical fiber section is longer than the length L2K+2of the second subsection of the (K+1)thoptical fiber section. That is, L2Kis greater than L2K+2(i.e. L2K>L2K+2) for any K (e.g. L2>L4>L6>L8> . . . ).

(3) The Relationship Between the Diameters of the First and the Second Subsections

The first subsection and the second subsection are coupled via the second tapered coupling section150having a diameter decreasing (tapered) in the light travelling direction. That is, the diameter D2K−1of the first subsection of the Kthoptical fiber section is larger than the diameter D2Kof the second subsection of the Kthoptical fiber section (i.e. D2K−1>D2K). Similarly, the diameter of the first subsection D2K+1of the (K+1)thoptical fiber section is larger than the diameter D2K+2of the second subsection of the (K+1)thoptical fiber section (i.e. D2K+1>D2K+2).

In the above example, when the diameters D1, D3, D5and D7of the first subsections are 120 um, respectively, and the diameters D2, D4, D6and D8of the second subsections are 95 um, 90 um, 95 um and 90 um, respectively, the relationship is satisfied.

The rougher the surface of an optical fiber device, the more back-scattering of light occurs on the surface. It is more likely that the surface gets rougher during etching as the diameter of the subsection gets smaller, and accordingly, more back-scattering may occur. The effect of back-scattering was reduced by making the diameter of the second subsection of the first optical fiber section larger than that of the second subsection of the second optical fiber section. That is, since occurrence of back-scattering in the first optical fiber section causes loss in the laser system, the second subsection D2having a relatively large diameter is provided in the first optical fiber section.

(4) The Relationship Between the Lengths of the First and the Second Subsections

The length L2K−1of the first subsection of the Kthoptical fiber section is shorter than the length L2Kof the second subsection of the Kthoptical fiber section. That is, L2K−1is smaller than L2K(i.e. L2K−1<L2K). Similarly, the length L2K+1of the first subsection of the (K+1)thoptical fiber section is shorter than the length L2K+2of the second subsection of the (K+1)thoptical fiber section. That is, L2K+1is smaller than L2K+2(i.e. L2K+1<L2K+2).

The extra light is emitted and removed through the second tapered coupling section150coupling the first subsection and the second subsection. In particular, by selecting the diameters and lengths of the first subsection and the second subsection to meet the conditions described above, and repeatedly disposing the second tapered coupling section150therebetween, extra light may be remove efficiently. As the light passes through the tapered coupling section150, the number of total reflections of light increases, and at the same time, light of low NA is changed to light of high NA that is relatively easy to remove such that extra light may be efficiently removed.

The characteristics of the second tapered coupling section150are determined by the relationship between the diameters of the first and the second subsections. As the difference between the two diameters increases, the slope of the second tapered coupling section150increases. As the slope increases, light having a low NA is converted into light having a high NA which may be removed more easily. When the slope at the first optical fiber section is greater than the slope at the second optical fiber section, portion of light that is not removed in the first optical fiber section may be removed in the second optical fiber section. In addition, by placing a relatively gentle slope in the first optical fiber section, the light may be removed evenly from the entire optical fiber device by preventing the light from being removed at once.

Hereinafter, a first embodiment and a second embodiment according to the present invention will be described in detail with reference toFIGS.3and4.

FIG.3is a cross-sectional view schematically illustrating a first embodiment of an optical fiber device for removing cladding light according to the present invention exemplifying the optical fiber device shown inFIG.2having four optical fiber sections (N=4) and each optical fiber section having one first subsection and one second subsection.

Referring toFIG.3, an optical fiber device1100for removing cladding light according to the first embodiment of the present invention includes a first, a second, a third and a fourth optical fiber sections and a total of three first tapered coupling sections250.

Each of the first optical fiber section through the fourth optical fiber section includes: one first subsection and one second subsection sequentially arranged along the light travelling direction; and a second tapered coupling section150that couples the first subsection and the second subsection.

The diameters D1, D3, D5and D7and the lengths L1, L3, L5and L7of the first subsections of the first optical fiber section through the fourth optical fiber section and the diameters D2, D4, D6and D8and the lengths L2, L4, L6and L8of the second subsections of the first optical fiber section through the fourth optical fiber section satisfy L1>L3>L5>L6, L2>L4>L6>L8, L1<L2, L3<L4, L5<L6, L7<L8, D1=D3=D5=D7and D2=D6>D4=D8according to the above-described relationships (1) through (4),

That is, the diameters D1, D3, D5and D7of the first subsections are constant regardless of K, and the diameters D2, D4, D6and D8of the second subsections are arranged as “large”, “small”, “large”, “small” depending on K (i.e. D2=D6>D4=D8). Further, the lengths L1, L3, L5and L7of the first subsections and the lengths L2, L4, L6and L8of the second subsections gradually decrease. The length of the second subsection of each optical fiber section is longer than the length of the first subsection of each optical fiber section (i.e. L1<L2, L3<L4, L5<L6and L7<L8).

FIG.4is a cross-sectional view schematically illustrating a second embodiment of an optical fiber device for removing cladding light according to the present invention exemplifying the optical fiber device shown inFIG.2having four optical fiber sections (N=4) and each optical fiber section having two first subsections and two second subsections.

Referring toFIG.4, an optical fiber device1200for removing cladding light according to the second embodiment of the present invention includes a first, a second, a third and a fourth optical fiber sections and a total of three first tapered coupling sections250.

Each of the first optical fiber section through the fourth optical fiber section includes: two first subsection and two second subsection alternately arranged along the light travelling direction; and second tapered coupling sections150that couples the first subsections and the second subsections.

The diameters D1, D3, D5and D7and the length L1, L3, L5and L7of the first subsections of the first optical fiber section through the fourth optical fiber section and the diameters D2, D4, D6and D8and the lengths L2, L4, L6and L8of the second subsections of the first optical fiber section through the fourth optical fiber section satisfy L1>L3>L5>L6, L2>L4>L6>L8, L1<L2, L3<L4, L5<L6, L7<L8, D1=D3=D5=D7and D2=D6>D4=D8according to the above-described relationships (1) through (4),

That is, the diameters D1, D3, D5and D7of the first subsections are constant regardless of K, and the diameters D2, D4, D6and D8of the second subsections are arranged as “large”, “small”, “large”, “small” depending on K (i.e. D2=D6>D4=D8). Further, the lengths L1, L3, L5and L7of the first subsections and the lengths L2, L4, L6and L8of the second subsections gradually decrease. The length of the second subsection of each optical fiber section is longer than the length of the first subsection of each optical fiber section (i.e. L1<L2, L3<L4, L5<L6and L7<L8).

Hereinafter, an apparatus for etching optical fiber and a method for etching optical fiber using the same according to the present invention will be described in detail with reference to the accompanying drawings.

FIGS.5,6and7are a perspective view, a plan view and a plan perspective view, respectively, illustrating an apparatus for etching optical fiber according to the present invention.

Referring toFIGS.5,6and7, the apparatus for etching optical fiber10according to the present invention includes: a main body100; two or more etching agent inlets200a,200b,210,220,230and240; two or more etching agent tanks300,310,320,330and340; isolation plates400,410,420and430; and etching units500,510,520,530and540.

The main body100is preferably in the shape of a step, and the two or more etching agent inlets200a,200b,210,220,230and240are provided on a first side, and an etching units500,510,520,530and540are provided on a second side. However, the main body100is not limited to the shape of a step. Optical fiber supports650aand650bare provided at both ends of the main body100, respectively, and grooves710are provided at each of the optical fiber supports650aand650b.

The two or more etching agent inlets200a,200b,210,220,230and240are provided on the first side of the main body100through which an etching agent is injected. Preferably, the two or more etching agent inlets200a,200b,210,220,230and240are provided at the first height to facilitate the injection of the etching agent.

The two or more etching agent inlets200a,200b,210,220,230and240are connected to two or more etching agent tanks300,310,320,330and340, respectively. The etching agent injected into the etching agent inlets200aand200bis stored in the etching agent tank300. The etching agent injected into the etching agent inlet210is stored in the etching agent tank310, the etching agent injected into the etching agent inlet220is stored in the etching agent tank320, the etching agent injected into the etching agent inlet230is stored in the etching agent tank330, and the etching agent injected into the etching agent inlet240is stored in the etching agent tank340.

The etching agent tanks300,310,320,330and340are provided inside the main body100and are isolated from one another by isolation plates400,410,420, and430. Specifically, the isolation plate400spatially isolates the two adjacent etching agent tanks300and310, the isolation plate410spatially isolates the two adjacent etching agent tanks310and320, the isolation plate420spatially isolates the two adjacent etching agent tanks320and330, and the isolation plate430spatially isolates the two adjacent etching agent tanks330and340.

That is, the exchange and the mixing of the etching agent in the etching agent tanks300and310are prevented by the isolation plate400, the exchange and the mixing of the etching agent in the etching agent tanks310and320are prevented by the isolation plate410, the exchange and the mixing of the etching agent in the etching agent tanks320and330are prevented by the isolation plate420, and the exchange and the mixing of the etching agent in the etching agent tanks330and340are prevented by the isolation plate430.

The etching units500,510,520,530and540provided at the second side of the main body100are spatially connected to the etching agent tanks300,310,320,330and340, respectively. The etching units500,510,520,530and540are provided at a second height lower than the first height at which the etching agent inlets200a,200b,210,220,230and240are provided, and the etching units500,510,520,530and540spatially connected to the etching agent tanks300,310,320,330and340, respectively, are filled with the etching agent when the etching agent tanks300,310,320,330and340are filled with the etching agent injected through the etching agent inlets200a,200b,210,220,230and240, respectively.

In addition, similar to the etching agent tanks300,310,320,330and340, the etching units500,510,520,530and540are isolated from one another by isolation plates400,410,420, and430. Specifically, the isolation plate400spatially isolates the two adjacent etching units500and510, the isolation plate410spatially isolates the two adjacent etching units510and520, the isolation plate420spatially isolates the two adjacent etching units520and530, and the isolation plate430spatially isolates the two adjacent etching units530and540.

That is, the exchange and the mixing of the etching agent in the etching units500and510are prevented by the isolation plate400, the exchange and the mixing of the etching agent in the etching units510and520are prevented by the isolation plate410, the exchange and the mixing of the etching agent in the etching units520and530are prevented by the isolation plate420, and the exchange and the mixing of the etching agent in the etching units530and540are prevented by the isolation plate430.

Hereinafter, the etching units500,510,520,530, and540will be described in more detail.

The etching unit500includes one or more etch baths500a,500b,500c,500d,500e,500fand500gspaced apart from each other at predetermined intervals. The insides600a,600b,600c,600d,600e,600fand600gof the etch baths500a,500b,500c,500d,500e,500fand500g, respectively, are filled with the etching agent, and the edge of each of the etch baths500a,500b,500c,500d,500e,500fand500gis provided with a groove700in which the optical fiber device to be etched is placed.

When an optical fiber device is placed in the grooves700, and the insides600a,600b,600c,600d,600e,600fand600gare filled with the etching agent, the optical fiber placed in the grooves700is etched. Specifically, when the etching agent is injected with the optical fiber placed in the groove700, only the portions of the optical fiber over the insides600a,600b,600c,600d,600e,600fand600gare etched by coming in contact with the etching agent while the portions of the optical fiber between the etch baths are not etched due to the lack of the etching agent between the etch baths.

The etching unit510includes one or more etch baths510a,510b,510cand510dspaced apart at a predetermined interval. The insides610a,610b,610cand610dof the etch bath510a,510b,510cand510d, respectively, are filled with the etching agent, and the edge of each of the etch baths510a,510b,510cand510dis provided with the groove700in which the optical fiber device to be etched is placed.

When an optical fiber device is placed in the grooves700, and the insides610a,610b,610cand610dare filled with the etching agent, the optical fiber placed in the grooves700is etched. Specifically, when the etching agent is injected with the optical fiber placed in the groove700, only the portions of the optical fiber over the insides610a,610b,610cand610dare etched by coming in contact with the etching agent while the portions of the optical fiber between the etch baths are not etched due to the lack of the etching agent between the etch baths.

The etching unit520includes one or more etch baths520a,520b,520c,520dand520espaced apart at a predetermined interval. The insides620a,620b,620c,620dand620eof the etch baths520a,520b,520c,520dand520e, respectively, are filled with the etching agent, and the edge of each of the etch baths520a,520b,520c,520dand520eis provided with the groove700in which the optical fiber device to be etched is placed.

When an optical fiber device is placed in the grooves700, and the insides620a,620b,620c,620dand620eare filled with the etching agent, the optical fiber placed in the grooves700is etched. Specifically, when the etching agent is injected with the optical fiber placed in the groove700, only the portions of the optical fiber over the insides620a,620b,620c,620dand620eare etched by coming in contact with the etching agent while the portions of the optical fiber between the etch baths are not etched due to the lack of the etching agent between the etch baths.

The etching unit530includes one or more etch baths530a,530b,530c,530d,530e,530fand530gspaced apart from each other at predetermined intervals. The insides630a,630b,630c,630d,630e,630fand630gof the etch baths530a,530b,530c,530d,530e,530fand530g, respectively, are filled with the etching agent, and the edge of each of the etch baths530a,530b,530c,530d,530e,530fand530gis provided with the groove700in which the optical fiber device to be etched is placed.

When an optical fiber device is placed in the grooves700, and the insides630a,630b,630c,630d,630e,630fand630gare filled with the etching agent, the optical fiber placed in the grooves700is etched. Specifically, when the etching agent is injected with the optical fiber placed in the groove700, only the portions of the optical fiber over the insides630a,630b,630c,630d,630e,630fand630gare etched by coming in contact with the etching agent while the portions of the optical fiber between the etch baths are not etched due to the lack of the etching agent between the etch baths.

The etching unit540includes one or more etch baths540a,540b,540c,540d,540e,540fand540gspaced apart from each other at predetermined intervals. The insides640a,640b,640c,640d,640e,640fand640gof the etch baths540a,540b,540c,540d,540e,540fand540g, respectively, are filled with the etching agent, and the edge of each of the etch baths540a,540b,540c,540d,540e,540fand540gis provided with the groove700in which the optical fiber device to be etched is placed.

When an optical fiber device is placed in the grooves700, and the insides640a,640b,640c,640d,640e,640fand640gare filled with the etching agent, the optical fiber placed in the grooves700is etched. Specifically, when the etching agent is injected with the optical fiber placed in the groove700, only the portions of the optical fiber over the insides640a,640b,640c,640d,640e,640fand640gare etched by coming in contact with the etching agent while the portions of the optical fiber between the etch baths are not etched due to the lack of the etching agent between the etch baths.

The etch baths500athrough500g,510athrough510d,520athrough520e,530athrough530gand540athrough540gare provided at a height (e.g. the second height) such that the respective etch bath connected to the etching agent tanks300,310,320,330and340is also filled with the etching agent when the etching agent tanks300,310,320,330and340are filled with the etching agent.

In addition, the interval at which the etch baths500a,500b,500c,500d,500e,500fand500gare arranged is preferably different from the interval at which the etch baths510a,510b,510cand510dare arranged. For example, the etching baths500a,500b,500c,500d,500e,500fand500gof the etching unit500may be spaced apart by a first distance while the etch baths510a,510b,510cand510dmay be spaced apart by a second distance different from the first distance. Similarly, the spacing of the etch baths500a,500b,500c,500d,500e,500fand500gmay differ from that of the etch baths520a,520b,520c,520dand520e, the spacing of the etch baths520a,520b,520c,520dand520emay differ from that of the etch baths530a,530b,530c,530d,530eand530f, and the spacing of the etch baths530a,530b,530c,530d,530eand530fmay differ from that of the etch baths540a,540b,540c,540d,540e,540fand540g.

FIG.8is a plan perspective view illustrating the apparatus for etching optical fiber according to the present invention, andFIGS.9A through9Fare cross-sectional views taken along lines A-A, B-B, C-C, D-D, E-E and F-F ofFIG.8, respectively.

Specifically,FIG.9Ais a cross-sectional view of the support650a, andFIG.9bis a cross-sectional view of a portion between the support650aand the etching unit500.FIG.9Cis a cross-sectional view of a portion where the etch bath500bis provided, andFIG.9Dis a cross-sectional view of a portion between the etch baths500cand500d.FIG.9Eis a cross-sectional view of a portion where the etching agent inlet200bis provided, andFIG.9Fis a cross-sectional view of a portion where the isolation plate400is provided. As shown inFIG.9F, the etching agent tanks300and310are completely isolated from each other by the isolation plate400.

FIG.10is a plan perspective view illustrating an apparatus for etching optical fiber according to the present invention, andFIGS.11A through11Dare cross-sectional views taken along lines G-G, H-H, I-I and J-J ofFIG.10, respectively.

Referring toFIGS.11A through11D, the etching agent tanks300,310,320,330and340are completely isolated from one another by isolation plates400,410,420and430. Similarly, the etching units500,510,520,530and540connected to the etching agent tanks300,310,320,330and340are also completely isolated from one another by the isolation plates400,410,420,430.

Hereinafter, a method for etching optical fiber device according to the present invention will be described in detail with reference toFIG.12.

The method for etching optical fiber device according to the present invention is performed using the apparatus for etching optical fiber device shown inFIG.5.

FIG.12is a flow chart illustrating the method for etching optical fiber device according to the present invention.

Referring toFIG.12, the optical fiber device is placed in the grooves700and710of the apparatus for etching optical fiber device shown inFIG.5(S100). The apparatus for etching optical fiber device shown inFIG.5includes a plurality of grooves700and710, and all of the grooves700and710are aligned so that a linear optical fiber device can be placed.

Thereafter, an etching agent is injected into the etching agent inlets200a,200b,210,220,230and240shown inFIG.5with a predetermined time difference for each etching agent inlet (S200). The reason for injecting the etching agent with a predetermined time difference for each etching agent inlet is to vary the degree of etching of the optical fiber device.

Hereinafter, the step S200will be described in detail with reference toFIG.13.

FIG.13is a flow chart illustrating in detail the step S200of the method according to the present invention shown inFIG.12.

As shown inFIG.13, the etching agent is injected into a first one of the two or more etching agent inlets connected to the etching unit provided with the one or more etch baths having a first spacing therebetween (S200a).

Thereafter, the etching agent is injected into a second one of the two or more etching agent inlets connected to the etching unit provided with the one or more etch baths having a second spacing therebetween, wherein the second spacing is smaller than the first spacing (S200b).

For example, the etching agent is injected into the etching agent inlets200aand200bconnected to the etching unit500provided with the etch baths with relatively large spacing therebetween to fill the etching unit500first with the etching agent via the etching agent tank300. Accordingly, the portion of the optical fiber device placed on the etching unit500is subjected to etching first. Thereafter, the etching agent is injected into the etching agent inlet210connected to the etching unit501provided with the etch baths relatively small spacing therebetween to fill the etching unit510second with the etching agent via the etching agent tank310. Accordingly, the portion of the optical fiber device placed on the etching unit510is subjected to etching next. Since the portion of the optical fiber device placed on the etching unit500is etched first, the degree of etching of the optical fiber device placed on the etching unit500is greater than the degree of etching of the optical fiber device placed on the etching unit510.

Similarly, when the etching agent is injected into the etching agent inlets220,230and240in sequence, the degree of etching of the portion of the optical fiber device placed on the etching units520is greater than that of the portion of the optical fiber device placed on the etching units530, and the degree of etching of the portion of the optical fiber device placed on the etching units530is greater than that of the portion of the optical fiber device placed on the etching units540. That is, the degrees of etching of the portions of the optical fiber device vary depending on the order of the injection of the etching agent into agent inlets220,230and240. Here, the order of the injection of the etching agent is not limited to the example described above. For example, of the etching agent may be injected at the same time, the order of the injection of the etching agent may be changed as desired, the time interval between the injections may be adjusted as desired. That is, the order of the injection and the time interval between the injections may be selected as desired depending on which portion of the optical fiber device is to be etched more.

Thereafter, the portions of the optical fiber device are etched for different etching time periods according to the time difference (S300).

Hereinafter, the step S300will be described in detail with reference toFIG.14.

FIG.14is a flow chart illustrating step S300of the method according to the present invention shown inFIG.12.

Referring toFIG.14, a first portion of the optical fiber device placed in the grove of the etching unit provided with the one or more etch baths having the first spacing therebetween is etched for a first time duration (S300a). A second portion of the optical fiber device placed in the grove of the etching unit provided with the one or more etch baths having the second spacing therebetween is etched for a second time duration shorter than the first time duration (S300b).

As described above, when the etching agent is sequentially injected, the portion of the optical fiber device placed on the etching unit into which the etching agent is injected first is subjected to etching first. The time duration of etching may be selected as desired after all the etching units are filled with the etching agent.

For example, when the etching agent is first injected into the etching agent inlets200aand200b, and the etching agent is then injected into the etching agent inlet210, the time duration of etching of the portion of the optical fiber device placed in the groove of the etching unit500having the etch baths with a relatively large spacing is longer than that of the portion of the optical fiber device placed in the groove of the etching unit510having the etch baths with a relatively small spacing.

The etching agent may be chosen based on the degree of etching, shape and time. In order to prevent the etching agent from leaking through the groove700and to uniformly etch the surface of the optical fiber, it is preferable that the surface tension of the etching agent is greater than 60 dyn/cm and smaller than the surface tension of water (75.6460 dyn/cm at 0° C.). For example, a mixture solution of two or more of sulfamic acid, ammonium fluoride, distilled water, and ammonium sulfate may be used as the etching agent.

Thereafter, the optical fiber device that has been etched is removed from the optical fiber device etching apparatus (S400). When the etching is completed, the optical fiber device for removing cladding light shown inFIG.2is obtained.

The optical fiber device for removing cladding light, the apparatus and the method for etching optical fiber device according to the present invention have the following advantageous effects.

(1) The excess light may be efficiently removed by repeatedly provided the tapered coupling section.

(2) The damage by heat from the light may be prevented by appropriately adjusting the lengths of the first and the second subsections.

(3) The surface area of the tapered coupling section may be increased by appropriately adjusting the diameters of the first and the second subsections to efficiently remove the excess light.

(4) The time duration for etching of the portions of the optical fiber may be precisely controlled by injecting the etching agent with time differences.

(5) The optical fiber device having a desired shape may be manufactured since the optical fiber device may be partially etched as desired.