Optical fiber prefabricated structure for preparing light-induced helical structure and light-induced helical structure optical fiber

Abstract

The invention discloses an optical fiber prefabricated structure for preparing a light-induced spiral structure and an optical fiber of the light-induced spiral structure, the optical fiber for preparing the light-induced spiral structure is composed of a fiber core layer, a high-photosensitivity inner cladding and an outer cladding, the spiral structure is formed depending on light-induced refraction, and a light-induced refraction area is located in the inner cladding. According to the optical fiber with the light-induced spiral structure, different material schemes are adopted on different layer structures, a quartz material is generally used as the basis, and meanwhile element doping is carried out on a fiber core layer and an inner wrapping layer. The light-induced spiral structure can be realized in a single-spiral mode and can also be represented in more multi-spiral modes such as a double-spiral mode, a triple-spiral mode and the like, the rotation period of each spiral of the multi-spiral structure can be regulated and controlled respectively, the spiral of the multi-spiral structure is formed from top to bottom in the same mode, and the multi-spiral structure is represented as a geometric structure symmetrical about the fiber core in position. The optical fiber with the light-induced spiral structure provided by the invention is expected to provide an optical fiber scheme with relatively strong competitiveness for application in various fields such as high-precision and high-stability all-fiber current sensors.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber design technology, and specifically to an optical fiber prefabricated structure for preparing a helical structure and a light-induced helical structure optical fiber prepared by using the prefabricated structure. Background Art

[0002] Spinning optical fiber is an optical fiber with significant low linear birefringence. This concept was first proposed by AJBarlow and others from the University of Southampton in 1981. In the following years, many different spinning optical fibers and corresponding preparation methods have been developed by various enterprises, research institutes, and universities, such as CoreCom in Italy, Corning and Bell Labs in the United States, and Changfei and Shanghai University in China.

[0003] Structured light is a projection formed by projecting a pre-set specific light beam onto an object from a certain angle. In the development of optical devices, researchers have tried to use light field control devices to adjust various parameters of light, including polarization state, to form specific structured light fields. These light fields have specific structural distributions, and their novel and unique physical properties make them highly valuable for research and application.

[0004] A vortex beam is a type of light beam with an annular intensity distribution, carrying orbital angular momentum, and a spiral wavefront structure. In an optical vortex, light is twisted around its axis in a spiral shape, so a vortex beam can also be called a spiral beam. Vortex light is a new type of structured light field that has received widespread attention and research, and has been widely used in quantum communications, beam shaping and other fields. As early as the 1830s, British scientist GB Airy first discovered the existence of vortex light when using a lens for experimental observation. So far, the use of optical fiber generation method, by designing the structure of the optical fiber and adjusting its characteristics, to achieve the generation and transmission of vortex light, is a relatively common way to generate vortex light. However, existing generation technologies generally have problems such as the inability to generate multiple beams at the same time, the single nature of the generated beams, fixed parameters, and the difficult control of the generation process.

[0005] The aforementioned rotated optical fiber can form a unique helical structure during its preparation process and has some typical optical properties. For example, the circular birefringence introduced therein can suppress the linear birefringence of the optical fiber. This optical rotation property provides more possibilities for the application of optical fiber in related fields such as current sensing, supercontinuum, polarization filtering, etc. However, generally speaking, the principle of existing rotated optical fiber technology is relatively simple, and there is no preparation process for forming a helical structure in a photoinduced manner. Generally, it can only be prepared by mechanical methods such as online rotating preform rods or heating and twisting optical fibers, and there are often defects such as low drawing speed and inability to guarantee stability. In addition, there is a lack of relevant research in the field of designing multi-helical structures in rotated optical fibers and controlling the different properties of the helix. This series of problems urgently need to be improved. Summary of the invention

[0006] Technical problem to be solved by the present invention: In view of the problem that it is difficult and has poor parameters to prepare a spiral structure in an optical fiber in the prior art, the present invention proposes an optical fiber that can form a spiral structure by using light. There is a layer of structure with high photosensitivity inside the optical fiber, and the spiral structure is prepared by using light refraction.

[0007] The technical solution of the present invention:

[0008] An optical fiber for preparing a photoinduced helical structure is characterized in that the optical fiber is composed of a core, an inner cladding and an outer cladding from the inside to the outside, wherein the inner cladding has strong photosensitivity, while the core and the outer cladding show weak photosensitivity.

[0009] The inner cladding is doped with Si, B, Ge, Sn and Pb elements based on quartz material to improve photosensitivity.

[0010] The fiber core is doped with Si, P and Ge elements based on quartz material.

[0011] There is a barrier layer between the inner cladding and the core.

[0012] The core and barrier layer are made by a series of vapor deposition processes, with the barrier layer deposited before the core.

[0013] A photoinduced helical structure optical fiber, comprising any of the above optical fibers for preparing a photoinduced helical structure, characterized in that the helical structure is inscribed in the inner cladding by light illumination.

[0014] The helical structure may be configured as a single helix or a multi-helix structure.

[0015] The helical structure period of the optical fiber can be controlled to be constant.

[0016] By regulating the rotation and feeding of the illumination device, a spiral structure with a variable period can be prepared.

[0017] For the multi-helical structure, each helical structure may have the same period or different periods. At the same time, different helical structures may have different choices in terms of a constant period or a gradual period.

[0018] The beneficial effects of the present invention are:

[0019] 1. The novel doped quartz optical fiber material, novel highly photosensitized inner cladding structure, and the combination with the vapor deposition process provided by the present invention can effectively improve the photorefractive index and efficiency and enhance the feasibility of preparing the optical fiber.

[0020] 2. The optical fiber with a photoinduced helical structure provided by the present invention has different photosensitivity properties in each layer structure. By utilizing the process in which the highly photosensitive layer undergoes refraction under the action of light, a helical structure can be prepared in the desired layer structure.

[0021] 3. The optical fiber with the photoinduced helical structure provided by the present invention effectively suppresses the influence of linear birefringence by introducing a large amount of uniform circular birefringence. At the same time, the pitch can be adjusted as needed, and the pitch can be much smaller than the best results of the currently reported rotating optical fiber pitch.

[0022] 4. The optical fiber with the photoinduced helical structure provided by the present invention has a very wide range of application scenarios. For example, it has a foreseeable positive impact on the performance of current sensing, such as sensitivity, measurement accuracy and stability, and is expected to provide an alternative sensing optical fiber for the monitoring of ultra-high voltage and large current. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the overall structure of a single helical optical fiber of the present invention, wherein the helical structure shown rotates in a periodic and gradual manner;

[0024] Figure 2 Schematic diagram of the overall structure of a single helical optical fiber of the present invention, wherein the helical structure shown rotates in a fixed periodic manner;

[0025] Figure 3 Schematic diagram of the overall structure of the double helix mode of the optically induced helical structure optical fiber of the present invention, wherein the two helical structures shown rotate with equal periods;

[0026] Figure 4 It is a schematic cross-sectional structure diagram of the double helical structure of the optical fiber of the present invention;

[0027] Figure 5 It is a schematic diagram of the cross-sectional structure of the triple-helix structure optical fiber of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] Example:

[0030] The present invention provides an optical fiber with a photoinduced helical structure, which aims to obtain a unique helical structure in the optical fiber based on the principle of photoinduced refraction, generate a new type of structured light, vortex light, and realize the adjustable and controllable properties of the helical structure in terms of quantity, period, etc. In a specific embodiment of the present invention, the optical fiber with a photoinduced helical structure is composed of a core layer, a highly photosensitized inner cladding, and an outer cladding. The formation of the helical structure depends on photoinduced refraction, and the photoinduced refraction zone is located in the inner cladding. The optical fiber with a photoinduced helical structure adopts different material schemes in its different layer structures, generally based on quartz materials, and the core layer and the inner cladding are doped with elements. The photoinduced helical structure of the present invention can be realized in a single helix mode, or in a double helix, triple helix, or other more multi-helix modes, wherein the rotation period of each helix of the multi-helix structure can be equal or unequal, and is formed from top to bottom in the same way, and is in a positional geometric structure symmetrical about the core.

[0031] An optical fiber for preparing a photoinduced helical structure: from the inside to the outside, there are a core, an inner cladding and an outer cladding. The inner cladding is doped with Si, B, Ge, Sn and Pb elements on the basis of quartz material to improve photosensitivity, and the core is doped with Si, P and Ge elements on the basis of quartz material, so that a structure with high photosensitivity of the inner cladding and low photosensitivity of the core is obtained. Under the same lighting conditions, the inner cladding will be refracted due to its high photosensitivity. On the basis of pulling the optical fiber downward, the light is allowed to make a spiral motion relative to the optical fiber, so that a spiral structure can be engraved in the inner cladding.

[0032] Furthermore, a barrier layer can be prepared between the inner cladding and the core by doping P, F and other materials to prevent light from affecting the core or irradiating the inner cladding on the opposite side through the core, and at the same time, the influence of the doping material on the optical fiber transmission loss can be effectively reduced. The thickness of the barrier layer can be adjusted according to the diameter of the optical fiber.

[0033] The optical fiber with a photoinduced helical structure obtained by photolithography, its overall composition structure and the rotation effect of the helix therein refer to Figure 1-Figure 3 As shown. Among them, Figure 1 and Figure 2 The schemes adopted in are all single helix. And, Figure 1 The rotation period of the middle helical structure presents a gradual characteristic in an optical fiber. The helical rotation here undergoes three cycles. The rotation period of the helical trajectory from top to bottom gradually shortens, and its period shows a relationship of 3:2:1 in length. Figure 2 The rotation period of the helical structure remains fixed, and 4 periods are shown in the figure. Figure 3The scheme adopted is a double helix, and its spiral trajectory is located in the highly photosensitive inner cladding, rotating in a symmetrical manner about the core and wrapped around the outer periphery of the core. The trajectory position fully fits the inner cladding. The rotation periods of the two trajectories here are the same and remain unchanged, and the figure shows 2 periods.

[0034] Any cross section of the optical fiber with a photoinduced helical structure presents a structure of a combination of circles and rings, with the core layer, inner cladding, and outer cladding arranged from the inside to the outside. The photoinduced helical structure appears as a fan-shaped structure in the cross section, present in the inner cladding. Figure 4 and Figure 5 As shown, Figure 4 The scheme adopted is a double helix, Figure 5 The scheme adopted is a triple helix.

Claims

1. An optical fiber prefabricated structure for preparing a photoinduced helical structure, characterized in that: From the inside to the outside, the optical fiber consists of the core, inner cladding and outer cladding. The inner cladding has strong photosensitivity, while the core and outer cladding have weak photosensitivity.

2. The optical fiber prefabricated structure for preparing a photoinduced helical structure according to claim 1, characterized in that: The inner cladding is doped with Si, B, Ge, Sn and Pb elements based on quartz material to improve photosensitivity.

3. The optical fiber for preparing a photoinduced helical structure according to claim 2, characterized in that: The fiber core is doped with Si, P and Ge elements based on quartz material.

4. The optical fiber prefabricated structure for preparing a photoinduced helical structure according to claim 3, characterized in that: There is a barrier layer between the inner cladding and the core.

5. The optical fiber prefabricated structure for preparing a photoinduced helical structure according to claim 4, characterized in that: The fiber core and the barrier layer are made through a series of vapor deposition processes. Before depositing the fiber core, materials such as P and F are deposited to obtain the barrier layer.

6. An optical fiber with a photoinduced helical structure, prepared by using the optical fiber prefabricated structure for preparing a photoinduced helical structure according to any one of claims 1 to 5, characterized in that: The helical structure is written by light illumination and is written in the inner cladding.

7. The optically induced helical structure optical fiber according to claim 6, characterized in that: The helical structure is configured as a single helix or a multi-helix structure.

8. The optically induced helical structure optical fiber according to claim 7, characterized in that: The helical structure of the optical fiber is periodically controlled to be in a constant state.

9. The optically induced helical structure optical fiber according to claim 7, characterized in that: By regulating the rotation and feeding of the illumination device, a spiral structure with a variable period can be prepared.

10. The optical fiber with a photoinduced helical structure according to claim 9, characterized in that: For a multi-helical structure, each helical structure has the same period or a different period, and different helical structures can make different choices in terms of a constant period or a gradually changing period.

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