Optical fiber and the manufacturing method thereof

FIELD OF THE INVENTION

0001The present invention relates to an improved optical fiber and the manufacturing method thereof, and more particularly, to an optical fiber having microstructures formed therein for blocking and scattering light traveling along its length and thus directing the light to emit radially from side walls of the optical fiber, in that each microstructures is a simple structure and can be formed inside the optical fiber by a simple manufacturing method without damaging the surface of the optical fiber, by which not only the risk of the optical fiber being snapped/deformed while the optical fiber is subjecting to an external force and bended is reduced, but also the light efficiency as well as the light uniformity of the optical fiber are improved.

BACKGROUND OF THE INVENTION

0002An optical fiber (or fiber optic) is a glass or plastic fiber designed to guide light along its length by total internal reflection, which is primarily composed of a core wrapped by a caldding layer. Optical fibers are widely used in all kind of fiber-optic communications, which permits digital data transmission over longer distances and at higher data rates than electronic communication as it is comparatively less expensive, thinner and lighter, and having less signal degradation, and so on.

0003Fibers are also widely used in illumination applications. They are used as light guides in medical and other applications where bright light needs to be shone on a target without a clear line-of-sight path. In some buildings, optical fibers are used to route sunlight from the roof to other parts of the building. Optical fiber illumination is also used for decorative applications, including signs, art, and artificial Christmas trees. It is noted that, by applying optical fibers in a illumination device, the number of light sources, i.e. fluorescent tubes for example, can be reduced and thus the light source utilization efficient is enhanced. Therefore, more and more illumination devices, each comprising a plurality of optical fibers, are being adapted as backlight modules. Normally the light entering from one end of an optical fiber passes out the other end thereof after a certain amount of loss takes place. It is known that instead of increasing the brightness of light sources used in one such backlight module, the brightness of the backlight module can be increased by adopting optical fibers of high transparency so as to ensure a low light loss during the transmission. However, if the surface of the optical fiber is disrupted as by scratching or otherwise deformed as by bending the optical fiber at a plurality of discrete locations along its length such that the angle of bend approximately exceeds the angle of internal reflection, light will be emitted at these locations.

0004Please refer to <figref idref="DRAWINGS">FIG. 1</figref>, which shows a fiber optic light emitting panel, disclosed in U.S. Pat. No. 4,885,663, entitled “FIBER OPTIC LIGHT EMITTING PANEL AND METHOD OF MAKING SAME”. As seen in <figref idref="DRAWINGS">FIG. 3</figref>, a plurality of optical fibers <b>5</b> are woven or plaited together to form a sheet or a mat. Light is encouraged to leave each fiber through its side wall by the relatively sharp bends imposed upon the fiber by the act of weaving/platting the material. A portion of the light incident upon each bend exceeds the critical angle for internal reflection and escapes from the fiber. In addition, a coating <b>18</b> used is a clear epoxy which changes the attenuation a predetermined amount. Also, a lenticular or prismatic film <b>1</b> is desirably mounted on the front of the emitter surface of the light emitting panel to shift the angular emission of light. With the coating <b>18</b> and the lenticular, the light output can be made relatively uniform over substantially the entire light emitting surface. However, although the weaving/platting operation is not necessary causing breakages to the optical fiber <b>5</b>, the bending of each optical fiber <b>5</b> by the weaving/platting operation can not be controlled at will so that light emitting uniformity is not satisfactory, not to mention that its manufacturing cost is relatively higher as its structure is more complicated. Furthermore, the light emitting panel, by its very nature, is only marginally flexible since the woven plait of the optical fibers <b>5</b> may be deformed and thus change the bending degree of each sharp bend when the light emitting panel is bended, thereby affecting its light emitting direction and optical efficiency.

0005Please refer to <figref idref="DRAWINGS">FIG. 2</figref>, which shows a cross section of a backlighting panel, disclosed in U.S. Pat. No. 5,226,105, entitled “FIBER OPTIC BACKLIGHTING PANEL AND DOT PROCESS FOR MAKING SAME”. As seen in <figref idref="DRAWINGS">FIG. 2</figref>, the fiber optic backlighting panel having two layers of optical fibers <b>24</b> and <b>24</b><i>a </i>arranged adjacent to each other. The optical fibers are selectively terminated at the different locations by forming holes through the layer of optical fibers with a laser, so that light transmitted along the length of each optical fiber can be emitted therefrom. However, as there is no reflective means being used for reflecting light beamed in each optical fiber out of its dotted hole, it can not provide satisfactory illumination. In order to improve the foregoing shortcoming, a bubble-like formations in the foam <b>60</b> is applied upon the two layers of optical fibers <b>24</b> and <b>24</b><i>a </i>for scattering the light, causing it to diffuse so as to provide uniform illumination or glow throughout the device. The foam <b>60</b> is preferably white in color and translucent. However, not to mention that its manufacturing cost is relatively higher and it is difficult to make as its structure is more complicated, the optical fibers <b>24</b>, and <b>24</b><i>a </i>are extremely easy to break or deform at those dotted locations since the surfaces there are damaged by the laser, thereby affecting its light emitting direction and optical efficiency.

0006Please refer to <figref idref="DRAWINGS">FIG. 3</figref>, which shows an optical fiber having a diffusion line, disclosed in U.S. Pat. No. 6,714,185, entitled “BACK LIGHTING APPARATUS OF LIQUID CRYSTAL DISPLAY USING OPTICAL FIBER”. As seen in <figref idref="DRAWINGS">FIG. 3</figref>, a diffusion line <b>621</b> is formed on the surface of an optical fiber <b>62</b> by a surface processing method for light scattering, which can be formed as a plurality of diffusion plates arranged lengthwise, spaced at a certain distance, along the optical fiber <b>62</b>; or is continuous in the lengthwise direction of optical fiber <b>62</b>; or can be composed of at least two longitudinal diffusion lines, arranged parallel to each other. Moreover, the diffusion line <b>621</b> can be formed by an etching method or a lithography method. In addition, the back lighting apparatus of a liquid crystal display apparatus using an optical fiber according to the present invention is capable of implementing a three-dimensional (3D) image by concurrently illuminating two pixel lines using one optical fiber having two diffusion lines. Nevertheless, if the diffusion line <b>621</b> is formed by an etching method, the surface of the optical fiber is damaged; and if it is formed by a lithography method, its precision is in question. Furthermore, as there is no reflective means being used for reflecting light beamed in each optical fiber out of its dotted hole, it can not provide satisfactory illumination, not to mentioned that the light is further being scattered by the diffusion line <b>621</b>.

0007Please refer to <figref idref="DRAWINGS">FIG. 4</figref>, which shows an optical fiber having a plurality of successive notches with reflecting surface formed thereon, disclosed in U.S. Pat. No. 5,432,876, entitled “ILLUMINATION DEVICES AND OPTICAL FIBERS FOR USE THEREIN”. As seen in <figref idref="DRAWINGS">FIG. 4</figref>, an optical fiber <b>2</b> has successive notches <b>4</b> of a variety of shapes to divert and reflect a proportion of the light propagating through the fiber to emit light from the fiber <b>2</b> by the reflecting surfaces <b>4</b>, <b>6</b> of each notch <b>4</b>. However, as the aforesaid optical fiber <b>2</b> is also damaged by the successive notches <b>4</b>, it can be easily broken right at the positions of those notches <b>4</b> when it is bended, thereby deforming the notches while affecting its light emitting direction and optical efficiency. In addition, not only it is difficult to form each notch <b>4</b> precisely at intended inclination angle and depth, but also the optical efficiency of the optical fiber <b>2</b> is low since each notch can reflect light only once.

0008From the above description, it is noted that the formation of microstructures on the surface of an optical fiber has the following shortcomings: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0009">(1) The microstructures formed on the surface of an optical fiber are easily being damaged by normal usage as it is exposed to outside environment.</li><li id="ul0002-0002" num="0010">(2) As the surface of an optical fiber is usually required to be applied by adhesive, the microstructures formed on the surface are thus contaminated, affecting the optical characteristics thereof.</li><li id="ul0002-0003" num="0011">(3) The microstructures formed on the surface are easily to be snapped or deformed while the optical fiber is subjecting to an external force and bended.</li></ul></li></ul>

0012Since all the aforesaid shortcomings will have adverse affect upon the side-emitting efficiency and uniformity of the optical fiber, it is in need of an improved optical fiber, that is free from the aforesaid shortcomings, for providing increased intensity of light at specific locations and uniformly distributed illumination throughout the device relative to the amount of light beamed in.

SUMMARY OF THE INVENTION

0013In view of the disadvantages of prior art, the primary object of the present invention is to provide an optical fiber having a plurality of microstructures formed upon a core of the aforesaid optical fiber, by which not only the plural microstructures are prevented from being damaged by normal usage and contacting to adhesive directly, but also they can lower the risk of the optical fiber being snapped/deformed while the optical fiber is subjecting to an external force and bended.

0014It is another object of the invention to provide an optical fiber having three-dimensional microstructures formed therein, by which the light efficiency and the light uniformity of the optical fiber are improved.

0015Yet, another object of the invention is to provide an optical fiber manufacturing method, capable of producing flexible optical fibers suitable to be adapted for any curved surface.

0016Furthermore, another object of the invention is to provide a method for manufacturing optical fibers, capable of controlling and adjusting the brightness of an optical fiber produced thereby by controlling the shape, quantity, size, distribution density and locations of microstructures to be formed inside the optical fiber.

0017To achieve the above object, the present invention provides an optical fiber, comprising: a core, having a plurality of microstructures formed therein; and a cladding layer, surrounding the core; wherein, as light is propagating along the core of the aforesaid optical fiber and strikes on the plural microstructures, it is scattered and reflected out of the optical fiber through a side wall thereof so as to achieve a side-emitting effect.

0018To achieve the above object, the present invention further provides a side-emitting method for optical fibers, comprising the steps of: (a) optically connecting an end of an optical fiber having a plurality of microstructures formed therein to a light source so as to feed light of the light source into the optical fiber; and (b) defining the plural microstructures to be so-structured for disrupting the internal reflection of the optical fiber that as soon as the light traveling along its length hit on any one of the plural microstructures, the light is scattered and sideway emitted out of the optical fiber.

0019Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

0020<figref idref="DRAWINGS">FIG. 1</figref> shows a fiber optic light emitting panel, disclosed in U.S. Pat. No. 4,885,663.

0021<figref idref="DRAWINGS">FIG. 2</figref> shows a cross section of a backlighting panel, disclosed in U.S. Pat. No. 5,226,105.

0022<figref idref="DRAWINGS">FIG. 3</figref> shows an optical fiber having a diffusion line, disclosed in U.S. Pat. No. 6,714,185.

0023<figref idref="DRAWINGS">FIG. 4</figref> shows an optical fiber having a plurality of successive notches with reflecting surface formed thereon, disclosed in U.S. Pat. No. 5,432,876.

0024<figref idref="DRAWINGS">FIG. 5</figref> shows an optical fiber having a microstructure formed therein according to a preferred embodiment of the invention.

0025<figref idref="DRAWINGS">FIG. 5A</figref> shows an optical fiber having a plurality of microstructures formed therein according to a preferred embodiment of the invention.

0026<figref idref="DRAWINGS">FIG. 6</figref> is a schematic diagram depicting a system used for forming microstructures in an optical fiber according to the present invention.

0027FIG. <b>6</b>A(a) is a front view of a first test sample used in the invention.

0028FIG. <b>6</b>A(b) is a side view of a first test sample used in the invention.

0029FIG. <b>6</b>B(a) is a front view of a second test sample used in the invention.

0030FIG. <b>6</b>B(b) is a side view of a second test sample used in the invention.

0031<figref idref="DRAWINGS">FIG. 7</figref> is a schematic diagram illustrating a first method of forming a plurality of microstructures inside an optical fiber according to the present invention.

0032<figref idref="DRAWINGS">FIG. 8</figref> is a schematic diagram illustrating three concentric circles of microstructures being formed inside an optical fiber by the first method of <figref idref="DRAWINGS">FIG. 7</figref>.

0033<figref idref="DRAWINGS">FIG. 9</figref> is a schematic diagram illustrating two triangular arrays of microstructures being formed inside an optical fiber while arranging the two arrays to be symmetrical to the axis of the optical fiber by the first method of <figref idref="DRAWINGS">FIG. 7</figref>.

0034<figref idref="DRAWINGS">FIG. 10</figref> is a schematic diagram illustrating a second method of forming a plurality of microstructures inside an optical fiber according to the present invention.

0035<figref idref="DRAWINGS">FIG. 11</figref> is a schematic diagram illustrating two radial-distributed concentric circles of microstructures being formed inside an optical fiber by the second method of <figref idref="DRAWINGS">FIG. 10</figref>.

0036<figref idref="DRAWINGS">FIG. 12</figref> is a schematic diagram illustrating a third method of forming a plurality of microstructures inside an optical fiber according to the present invention.

0037<figref idref="DRAWINGS">FIG. 13</figref> is a schematic diagram depicting the formation of microstructures inside an optical fiber using a plurality of laser devices.

0038<figref idref="DRAWINGS">FIG. 14</figref> is a schematic diagram showing a process integrating the formation of microstructures with the manufacturing of an optical fiber according to the present invention.

0039<figref idref="DRAWINGS">FIG. 15</figref> is a schematic diagram showing an optical fiber structure composed of a plurality of optical fibers according to an embodiment of the present invention.

0040<figref idref="DRAWINGS">FIG. 16</figref> is a schematic diagram showing an optical fiber structure composed of a plurality of optical fibers according to another embodiment of the present invention.

0041<figref idref="DRAWINGS">FIG. 17</figref> is a schematic diagram showing an optical fiber structure of the invention, structured and used as a fiber optic backlighting panel.

0042<figref idref="DRAWINGS">FIG. 17A</figref> is an A-A cross section of <figref idref="DRAWINGS">FIG. 17</figref>.

0043<figref idref="DRAWINGS">FIG. 18</figref> a schematic diagram showing an optical fiber structure of the invention, structured and used as a flexible illumination device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

0044For your esteemed members of reviewing committee to further understand and recognize the fulfilled functions and structural characteristics of the invention, several preferable embodiments cooperating with detailed description are presented as the follows.

0045Please refer to <figref idref="DRAWINGS">FIG. 5</figref>, which shows an optical fiber having a microstructure formed therein according to a preferred embodiment of the invention. The purpose of forming the microstructure <b>20</b> inside the optical fiber <b>10</b> is to enable the optical fiber <b>10</b> to emit light radially from the side wall thereof. In <figref idref="DRAWINGS">FIG. 5</figref>, the optical fiber <b>10</b> is substantially composed of a core <b>11</b> wrapped by a cladding layer <b>12</b>, that can be made of a transparent material, such as plastic, glass, quartz, etc., and can be cylindrical in shape, or other geometrical shapes at will. The microstructure <b>20</b> is arranged on the core <b>11</b> in a manner that the shape, quantity, size, distribution density and location are only dependent upon actual requirement and thus are not limited by any rule. Thus, there can be only one microstructure <b>20</b> formed on the core <b>11</b>, as seen in <figref idref="DRAWINGS">FIG. 5</figref>, or there can be a plurality of microstructures <b>20</b>, as seen in <figref idref="DRAWINGS">FIG. 5A</figref>. For a cylindrical-shaped optical fiber <b>10</b>, the size of each microstructure <b>20</b> should be no larger than the diameter of the core <b>11</b>, and preferably each microstructure <b>20</b> may be a structure of regular shape or a structure of irregular shape.

0046As seen in <figref idref="DRAWINGS">FIG. 5</figref>, an end of the optical fiber <b>10</b> is optically connected to a light source <b>30</b> for feeding the light <b>31</b> of the light source <b>30</b> into the optical fiber <b>10</b>. As the light <b>30</b> is guided to travel along the length of the optical fiber <b>10</b> by total internal reflection, represented by the reflected light <b>32</b>, and strikes on the microstructure <b>20</b>, the light <b>31</b> as well as the reflected light <b>32</b> will be scattered and reflected out of the optical fiber through a side wall thereof so as to achieve a side-emitting effect since the scattered light <b>33</b> exceeds the critical angle for internal reflection. It is noted that the direction of the scattered light <b>33</b> being emitted radially out of the optical fiber <b>10</b> is dependent upon the three-dimension structure of the microstructure <b>20</b>. Furthermore, as the further the light <b>31</b> is traveling inside the optical fiber <b>10</b>, the weaker the brightness thereof will be since it is propagating by total internal reflection that will cause a certain amount of energy loss, it is preferred to formed the microstructure <b>20</b> basing on the following principle: the farther the positioning of the optical fiber is to the light source <b>30</b>, the higher the density of the microstructure <b>20</b> will be formed thereon, thereby, the brightness of the scattered light <b>33</b> emitted from the farther area of the optical fiber <b>10</b> is enhanced. That is, by controlling the shape, quantity, size, distribution density and location of the microstructure <b>20</b>, the brightness of the side-emitting optical fiber <b>10</b> can be adjusted correspondingly.

0047With the aforesaid optical fiber <b>10</b>, a side-emitting method for optical fibers can be provided, which comprises the steps of: <ul id="ul0003" list-style="none"><li id="ul0003-0001" num="0000"><ul id="ul0004" list-style="none"><li id="ul0004-0001" num="0048">(a) optically connecting an end of an optical fiber <b>10</b> having a plurality of microstructures <b>20</b> formed therein to a light source <b>30</b> so as to feed light <b>31</b> of the light source <b>30</b> into the optical fiber <b>10</b>; and</li><li id="ul0004-0002" num="0049">(b) defining the plural microstructures <b>20</b> to be so-structured for disrupting the internal reflection of the optical fiber <b>10</b> that as soon as the light <b>30</b> traveling along the length of the optical fiber <b>10</b> hit on any one of the plural microstructures <b>20</b>, the light <b>30</b> is scattered and sideway emitted out of the optical fiber <b>10</b>.</li></ul></li></ul>

0050Please refer to <figref idref="DRAWINGS">FIG. 6</figref>, which is a schematic diagram depicting a system used for forming microstructures in an optical fiber according to the present invention. In <figref idref="DRAWINGS">FIG. 6</figref>, the system used for forming microstructures in an optical fiber <b>10</b> is a laser device <b>40</b>, which can be a carbon dioxide laser device, a Nd-YAG laser device or an excimer laser device, etc., operating in a continuous or pulsed manner. The laser light <b>42</b> of the laser device <b>40</b> is focused to the interior of the optical fiber <b>10</b> by a lens set <b>41</b>, i.e. onto the core <b>11</b> of the optical fiber <b>10</b>. The sole purpose of the lens set <b>41</b> is to decide how the laser light <b>42</b> should be focused on the core and thus determine the size of the focal point being formed upon the core. It is noted that the size of the focal point will affect the size of the microstructure being formed on the core <b>11</b>, as those microstructures <b>20</b>, <b>20</b><i>a, </i><b>20</b><i>b </i>and <b>20</b><i>c, </i>shown in <figref idref="DRAWINGS">FIG. 6</figref>, and the physical attributes of the microstructure <b>20</b>, such as size, distribution density, and refraction index, etc., will all have affect upon the side-emitting brightness of the optical fiber <b>10</b>. Since the forming of the microstructures <b>20</b> by the laser device <b>40</b> is a contactless processing method, the cladding layer <b>12</b> of the optical fiber <b>10</b> will not be damaged, thereby, not only the microstructures <b>20</b> are protected from exposing to outside environment, but also the adverse affection upon the strength of the optical fiber <b>10</b> by forming the microstructures <b>20</b> on the core <b>11</b> is minimized.

0051The shape of the microstructure being formed by a laser device is primarily determined on two factors, that the first is related to the laser pulse duration and laser wavelength while another is related to the selecting of lens set <b>41</b> used for matching the laser device <b>40</b>. Technically, the forming of microstructure by a laser device is similar to laser engraving, however, the laser engraving technique is not seen being used for enabling an optical fiber to emit light from the side wall thereof. In an experiment of striking a 1064 nm laser light upon a sample glass through a lens set of F44 focal length, a pattern of about 100 μm˜250 μm in length L, 100 μm˜250 μm in width W, and about 100 μm˜200 μm in depth D, can be achieved, as those shown in <figref idref="DRAWINGS">FIG. 6(</figref><i>a</i>) and <figref idref="DRAWINGS">FIG. 6(</figref><i>b</i>) in respective. In another experiment of striking a 532 nm laser light upon a sample glass through a lens set of F22 focal length, a pattern of about 30 μm˜80 μm in length L, 30 μm˜80 μm in width W, and about 40 μm˜120 μm in depth D, can be achieved, as those shown in <figref idref="DRAWINGS">FIG. 6(</figref><i>a</i>) and <figref idref="DRAWINGS">FIG. 6(</figref><i>b</i>) in respective. Thus, it is evidenced that the dimension and depth of a microstructure being formed on the core of an optical fiber can actually be controlled by the selection of laser wavelength and the lens set.

0052Basing on the above system of forming microstructures on the core of an optical fiber, various manufacturing methods can be structured that can be used for achieving various microstructures of different distribution densities and styles.

0053In <figref idref="DRAWINGS">FIG. 7</figref>, an optical fiber <b>10</b> is substantially a cylindrical-shaped thread having an axis C extending along a Y-axis direction defined by an Cartesian coordinate system of X-axis, Y-axis and Z-axis, and a lens set <b>41</b> is fixedly positioned above the optical fiber at a location defined by the Z-axis for direction a laser beam <b>42</b> to downward-focus upon the core <b>11</b> of the optical fiber <b>10</b> following a Z-axis direction while the lens set <b>41</b> is capable of being driven to perform a two-dimensional movement with respect to the X- and the Y-axis, thereby, a two-dimensional matrix of microstructures <b>20</b> can be formed on the core <b>11</b>. Similarly, the two-dimensional matrix of microstructures <b>20</b> can be formed by fixed arranged the lens set <b>41</b> to a position without moving while enabling the optical fiber <b>10</b> to perform the two-dimensional movement. In another preferred embodiment, the lens set <b>41</b> is fixedly positioned at a position capable of directing the laser beam <b>42</b> to propagate along an Y-axis direction parallel to the axis C of the optical fiber <b>10</b> and focus upon the core <b>11</b> of the optical fiber <b>10</b>, while either the optical fiber <b>10</b> or the lens set <b>41</b> is capable of being driven to perform a two-dimensional movement with respect to the X- and the Z-axis, thereby, an array of microstructures can be formed with respect to a specific cross section of the optical fiber <b>10</b>. As seen in <figref idref="DRAWINGS">FIG. 8</figref>, there are three concentric circles of microstructures <b>20</b><i>a</i>˜<b>20</b><i>c </i>of reducing size being formed on the core <b>11</b> of the optical fiber <b>10</b>. Moreover, as seen in <figref idref="DRAWINGS">FIG. 9</figref>, there are two triangular arrays of microstructures <b>20</b> being formed inside an optical fiber while arranging the two arrays to be symmetrical to the axis C of the optical fiber <b>10</b>.

0054In <figref idref="DRAWINGS">FIG. 10</figref>, an optical fiber <b>10</b> is substantially a cylindrical-shaped thread having an axis C extending along a Y-axis direction defined by an Cartesian coordinate system of X-axis, Y-axis and Z-axis, and a lens set <b>41</b> is fixedly positioned above the optical fiber at a location defined by the Z-axis for direction a laser beam <b>42</b> to downward-focus upon the core <b>11</b> of the optical fiber <b>10</b> following a Z-axis direction while the optical fiber <b>10</b> is capable of being driven to rotate about its axis C, thereby, a plurality of microstructures <b>20</b> radially distributed around the axis C of the optical fiber <b>10</b> can be formed. In addition, by changing the focal point of the lens set <b>41</b>, another ring of radial-distributed microstructures <b>20</b><i>a </i>of smaller size can be formed, as seen in <figref idref="DRAWINGS">FIG. 11</figref>. Similarly, such rings of microstructures <b>20</b>, <b>20</b><i>a </i>can also be formed by fixedly arranged the optical fiber <b>10</b> to a position while enabling the lens set <b>41</b> to revolve around the optical fiber <b>10</b>. It is noted that microstructures of different distributions and circular alignments can be achieved with respect to different manners that such microstructures are to be formed.

0055As seen in <figref idref="DRAWINGS">FIG. 12</figref>, the plural spiral-aligned microstructures <b>20</b> are formed by simultaneously driving the lens set <b>41</b> and/or the optical fiber <b>10</b> to move and/or rotate. Moreover, there can be more than one lens sets to be used for forming microstructures at the same time, as the three lens sets <b>41</b><i>a, </i><b>41</b><i>b </i>and <b>41</b><i>c </i>shown in <figref idref="DRAWINGS">FIG. 13</figref>. The three lens sets <b>41</b><i>a, </i><b>41</b><i>b </i>and <b>41</b><i>c </i>are used respectively for directing their corresponding laser beams to propagating along different direction and focus at different position on the core <b>11</b>, and moreover, the three lens sets <b>41</b><i>a, </i><b>41</b><i>b </i>and <b>41</b><i>c </i>can be control to operate in a synchronous manner or an asynchronous manner, thereby, microstructures <b>20</b><i>a</i>˜<b>20</b><i>c </i>of different sizes can be achieved.

0056It is to be emphasized that no matter how the optical fiber <b>10</b> and the lens set <b>41</b> are to be activated, the corresponding laser beam is always being focused on the core <b>11</b> of the optical fiber <b>10</b> without causing any damage to its cladding layer <b>12</b>.

0057As the side-emitting effect of the optical fiber <b>10</b> disclosed in the present invention is achieve by the use of laser devices to form microstructures <b>20</b> on the core <b>11</b> of the optical fiber <b>10</b>, the formation of the microstructures <b>20</b> on the corell of the optical fiber <b>10</b> can be performed after the manufacturing of the optical fiber <b>10</b> or during the manufacturing of the optical fiber <b>10</b> by integrating the process of forming microstructures <b>20</b> into the manufacturing process of the optical fiber <b>10</b>, as seen in <figref idref="DRAWINGS">FIG. 14</figref>. In <figref idref="DRAWINGS">FIG. 14</figref>, as the optical fiber <b>10</b> is being pull out of a fiber drawing mold <b>60</b> while other required fiber drawing apparatuses are waived and not shown in the figure, the lens set <b>41</b> is positioned at a specific location adjacent to the fiber drawing mold <b>60</b> so as to focus laser beams onto the core <b>11</b> of the just-being-drawn optical fiber <b>10</b> for forming microstructures <b>20</b> thereon as soon as the optical fiber <b>10</b> emerges from the exit of the fiber drawing mold <b>60</b>.

0058As seen in <figref idref="DRAWINGS">FIG. 15</figref> and <figref idref="DRAWINGS">FIG. 16</figref>, an optical fiber structure composed of a plurality of optical fibers of the invention can be achieved for brightness enhancement. In <figref idref="DRAWINGS">FIG. 15</figref>, an optical fiber structure is substantially a stacking of two optic layers, each optical layer being composed of a plurality of parallel-arranged optical fibers <b>10</b> with microstructures <b>20</b> formed therein, by which the brightness of intended light-emitting surface of the optical fiber structure is improved. In <figref idref="DRAWINGS">FIG. 16</figref>, an optical fiber structure is substantially a bundle of optical fibers <b>20</b> having microstructures formed therein. It is noted the more such optical fibers <b>10</b> being bundled in the optical fiber structure of <figref idref="DRAWINGS">FIG. 16</figref>, the brighter the optical fiber structure will be, moreover, the plural optical fibers <b>10</b> can be weaved or twisted together, whichever is good for the brightness thereof.

0059Please refer to <figref idref="DRAWINGS">FIG. 17</figref> and <figref idref="DRAWINGS">FIG. 17A</figref>, which are respectively a schematic diagram showing an optical fiber structure of the invention, structured and used as a fiber optic backlighting panel, and a A-A cross sectional view thereof. In <figref idref="DRAWINGS">FIG. 17</figref>, a layer of optical fibers <b>10</b> are arranged adjacent to each other to be used as a fiber optic backlighting panel for transmitting the light beam therein to different locations throughout the panel, in which each optical fiber <b>10</b> has microstructures formed therein and is optically connected to a light source <b>30</b> by an end thereof while using a clapping device <b>70</b> to fixedly clip and align the end of the optical fiber <b>10</b> to the light source <b>30</b>. The mechanism, appearance and operating method of the clapping device <b>70</b> is known to those skilled in the art and thus are not described further herein. The purpose of disposing the clapping device <b>70</b> is to enable the light of the light source <b>30</b> to be feed smoothly into and propagating throughout each optical fiber <b>10</b>. Since the microstructures <b>20</b> formed inside each of the optical fiber <b>10</b> is so-structured that each is capable of disrupting the internal reflection of the optical fiber <b>10</b>, the light propagating along the length of each optical fiber <b>10</b> is scattered and sideway emitted out of the optical fiber <b>10</b> when the it hit on any one of the microstructures <b>20</b>, similar to that shown in <figref idref="DRAWINGS">FIG. 5</figref>. Thereby, the layer of optical fiber can be used as a fiber optic backlighting panel capable of transmitting the light beamed therein to different locations throughout the panel and thus providing increased and uniform intensity of light at specific locations or uniformly distributed light throughout the panel. Moreover, as the brightness of the fiber optic backlighting panel is achieved by the scattered light being emitted radially form the side wall of each optical fiber of the fiber optic backlighting panel, a reflective panel <b>71</b> and a brightness enhancement film <b>72</b> can be integrated into the fiber optic backlighting panel for brightness enhancement. As seen in <figref idref="DRAWINGS">FIG. 17A</figref>, the layer of optical fibers <b>10</b> is sandwiched between the reflective panel <b>71</b> and the brightness enhancement film <b>72</b>, by which the scattered light emitted out of each optical fiber <b>10</b> can be reflected to shine on the brightness enhancement film <b>72</b> by the reflective panel <b>71</b> where they are being focused thereby and assembled within a specific range, and thus the brightness of the fiber optic backlighting panel is enhanced. In addition, for providing uniformly distributed light throughout the panel, the distribution of the microstructures <b>20</b> inside each optical fiber <b>10</b> of the fiber optic backlighting panel is controlled by a manner that the closer the positioning of the optical fiber <b>10</b> is to the light source <b>30</b>, the lower the density of the microstructure <b>20</b> will be formed thereon, or the smaller the size of the microstructure <b>20</b> is; and vice versa. That is, by controlling the distribution density of the microstructure <b>20</b>, the uniformity of the side-emitting optical fiber <b>10</b> can be controlled correspondingly, which is similar in principle as that illustrated in <figref idref="DRAWINGS">FIG. 5</figref>.

0060Please refer to <figref idref="DRAWINGS">FIG. 18</figref>, which is a schematic diagram showing an optical fiber structure of the invention, structured and used as a flexible illumination device. The flexible illumination device, capable of being bended and deformed, is composed of a plurality of optical fibers <b>10</b>, being arranged adjacent to each other to form a flat panel while adhering to each other by an adhesive. Moreover, each optical fiber <b>10</b> has microstructures formed therein and every optical fiber <b>30</b> is optically connected to light sources by an end thereof while using a clapping device <b>90</b> to fixedly bundle all the ends of the optical fibers <b>10</b> to those light sources. The disposing of the clapping device <b>90</b> is to enable the light of those light sources to be feed smoothly into and propagating throughout each optical fiber <b>10</b>. Since the microstructures <b>20</b> formed inside each of the optical fiber <b>10</b> is so-structured that each is capable of disrupting the internal reflection of the optical fiber <b>10</b>, the light propagating along the length of each optical fiber <b>10</b> is scattered and sideway emitted out of the optical fiber <b>10</b> when the it hit on any one of the microstructures <b>20</b>, thereby, the illumination device is able to provide uniformly distributed light throughout the device. Similar to that illustrated in <figref idref="DRAWINGS">FIG. 17</figref>, for providing uniformly distributed light throughout the flexible illumination device, the distribution of the microstructures <b>20</b> inside each optical fiber <b>10</b> of the flexible illumination device is controlled by a manner that the closer the positioning of the optical fiber <b>10</b> is to the clapping device <b>90</b>, the lower the density of the microstructure <b>20</b> will be formed thereon, or the smaller the size of the microstructure <b>20</b> is; and vice versa. That is, by controlling the distribution density of the microstructure <b>20</b>, the uniformity of the side-emitting optical fiber <b>10</b> can be controlled correspondingly, which is also similar in principle as that illustrated in <figref idref="DRAWINGS">FIG. 5</figref>.

0061To sum up, different form those conventional method of forming microstructures on the surface of optical fibers, the present invention provides an optical fiber having a plurality of microstructures formed upon a core of the aforesaid optical fiber by a laser device, by which not only the plural microstructures are prevented from being damaged by normal usage and contacting to adhesive directly, but also they can lower the risk of the optical fiber being snapped/deformed while the optical fiber is subjecting to an external force and bended. An optical fiber is disclosed, which is comprised of: a core, having a plurality of microstructures formed thereon; and a cladding layer, surrounding the core. In a preferred embodiment, as light is transmitting along the axis of the aforesaid optical fiber and strikes on the plural microstructures, it is scattered and reflected out of the optical fiber through a side wall thereof so as to achieve a side-emitting effect. As the microstructures are formed inside the core of the aforesaid optical fiber, not only they are prevented from being damaged by normal usage, contacting to adhesive directly, but also they can lower the risk of the optical fiber being snapped/deformed while the optical fiber is subjecting to an external force and bended. In addition, by controlling the shape, quantity, size, distribution density and location of the microstructure, the brightness of the side-emitting optical fiber can be adjusted correspondingly.

0062While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.