CN115385576B - Cesium-containing glass, polygonal gradient refractive index fiber lens and method for preparing array thereof - Google Patents

Abstract

This application belongs to the technical field of optical glass drawing processing. In order to further improve the pixel filling rate and light energy utilization rate of the optical fiber array, a cesium-containing glass, a polygonal gradient refractive index fiber lens and an array preparation method thereof are proposed; a compound formulation of the cesium-containing glass is proposed. The ratio is: 40%-60%Cs ₂ O; 25%-40% SiO ₂ ; 5%-10% B ₂ O ₃ ; 3%-8% Al ₂ O ₃ ; 3%-9% ZnO; 5%- 10% Na ₂ O+K ₂ O; 0.5%-2% ZrO ₂ ; 3%-5% InF ₃ . This glass has a high cesium content, and the ion concentration gradient changes caused by the replacement of Cs ⁺ ions in the glass and K ⁺ ions in the high-temperature molten salt. Overall, the refractive index of the center and edge of the glass fiber is larger. Each unit pixel of the polygonal gradient refractive index lens array and fiber array made of the cesium-containing glass is a polygon, which reduces the triangular gap that exists when stacking between pixels; the unit pixel is a gradient refractive index material , no cladding is required, and light can be transmitted directly.

Description

Cesium-containing glass, polygonal gradient refractive index fiber lens and method for preparing array thereof

Technical field

This application belongs to the technical field of optical glass drawing processing, specifically involving glass formulas, gradient refractive index fibers and array preparation methods.

Background technique

Fiber optical devices such as optical fiber panels, optical fiber image beams, light transmission rods, fiber light cones, and fiber optic inverters are widely used in image detection, biometric identification, and image light guide identification devices. They are used in consumer electronics, medical health, intelligent security, and aviation. It has important application prospects in aerospace and other fields.

The interior of the fiber optic device is composed of countless sub-fibers, and each sub-fiber is called a unit pixel. The sub-fiber cross-sectional structure of traditional fiber optic devices is circular, consisting of a high-refractive index central core and a low-refractive index outer cladding. The unit pixel diameter is 3-10 microns, of which the cladding diameter is 0.4-0.6 microns. Due to the existence of the low refractive index cladding, the filling rate of the pixels in the entire fiber optic device layout is reduced, and the pixel structure is circular, and there are triangular gaps between pixels when stacked, further reducing the pixels' filling rate. Filling rate, the final overall filling rate of the pixel is about 70%, which affects the light energy utilization rate and imaging quality of fiber optics.

Contents of the invention

In order to further improve the pixel filling rate and light energy utilization rate of the optical fiber array, this application proposes a method for preparing a cesium glass and polygonal gradient refractive index cesium glass optical fiber array.

A cesium-containing glass, made of the following compounds, with weight percentage of ingredients: 40%-60% Cs ₂ O; 25%-40% SiO ₂ ; 5%-10% B ₂ O ₃ ; 3%-8% Al ₂ O ₃ ; 3%-9% ZnO; 5%-10% Na ₂ O+K ₂ O; 0.5%-2% ZrO ₂ ; 3%-5% InF ₃ .

Cs ₂ O is the main component of glass and is used to achieve ion replacement with K ⁺ ions in high-temperature molten salt, so that the Cs ⁺ ion concentration gradually decreases and the K ⁺ ion concentration gradually increases from the center to the edge of the glass fiber. Since the unit refractive index of Cs ⁺ ions in glass is 1.76 and the unit refractive index of K ⁺ ions in glass is 1.57, the ion concentration gradient change caused by the replacement of Cs ⁺ ions in the glass and K ⁺ ions in the high-temperature molten salt makes The refractive index decreases, so that the refractive index from the center to the edge of the glass fiber gradually decreases as a whole;

SiO ₂ is a glass product and is the main component of the glass. To ensure that the glass production temperature does not exceed 1450 degrees, the content of this component generally does not exceed 65%; choosing a weight composition of 25%-40% can ensure the glass melting temperature at 1380-1420 degrees;

B ₂ O ₃ is a flux to ensure that SiO ₂ and other glass components can be fully melted into glass;

Al ₂ O ₃ and ZnO are glass intermediates that structurally serve as bridges connecting Si ⁴⁺ ions and Cs ⁺ ions, Na ⁺ ions, K ⁺ ions, In ³⁺ ions and other monovalent and trivalent ions, while ensuring that Cs The stability of the overall structure of the glass during the ion exchange process between ⁺ ions and K ⁺ ions in the molten salt improves the high-temperature corrosion resistance of the glass;

Na ₂ O + K ₂ O monovalent oxide is a glass structure network modification body, used to reduce the glass forming temperature. The mixing ratio of these components can regulate the ion exchange temperature and speed of cesium glass;

ZrO ₂ is used to improve the anti-crystallization performance during glass drawing or multiple fiber drawing processes.

InF ₃ is used to bridge monovalent network modifying ions such as Cs ⁺ ions, Na ⁺ ions, and K ⁺ ions to ensure the stability of the glass network structure and improve the chemical stability of the glass during high-temperature ion exchange. At the same time, it is mixed with Cs ₂ O The ratio is conducive to controlling the deviation between the refractive index distribution index generated by ion exchange and the theoretical calculation.

As preferred: weight percentage of ingredients: 42%-55% Cs ₂ O; 25%-33% SiO ₂ ; 6%-8% B ₂ O ₃ ; 3%-5% Al ₂ O ₃ ; 4%-6% ZnO ; 5%-8% Na ₂ O + K ₂ O; 1%-2% ZrO ₂ ; 3%-5% InF ₃ .

The advantages of this cesium-containing glass are: the high cesium content, the large difference in ion concentration gradient changes caused by the replacement of Cs ⁺ ions in the glass and K ⁺ ions in the high-temperature molten salt, thus gradually reducing the refractive index from the center to the edge of the glass filament as a whole. The amplitude is large and the color difference is small.

A method for preparing polygonal gradient refractive index fiber:

1) Mix each compound to prepare a cesium-containing glass batch;

2) Smelt the cesium-containing glass batch in a platinum crucible at a temperature of 1380-1420 degrees, and then shape it into cylindrical glass;

3) Process the cylindrical glass into a polygonal cylindrical glass with a cross-section, and the side walls of the polygonal cylindrical glass are all polished;

4) Place the polygonal columnar glass on a drawing machine and draw it into continuous polygonal glass fiber;

5) Put the polygonal glass fiber into molten potassium nitrate salt at 500-600°C for Cs ⁺ -K ⁺ ion exchange, thereby forming a polygonal gradient refractive index fiber with a gradually decreasing refractive index from the center to the edge.

The number of sides of the polygon is preferably: 2 (n+1), where n is a natural number. For example, when it is four, six, or octagonal, the refractive index on the cross-section of the polygonal glass fiber monofilament is symmetrically distributed about the center.

Preferably, the diameter of the cylindrical glass is 50 to 70 mm, and the cross-sectional side length of the polygonal cylindrical glass is 15 to 35 mm and the length is 300 to 600 mm.

The polygonal gradient refractive index fiber preferably has a length of 200 to 600 mm and a cross-sectional side length of 1 to 5 mm.

The gradient refractive index fiber made by the above method can be processed into a polygonal gradient refractive index fiber lens by cutting it to a certain length and polishing both end surfaces.

The gradient refractive index fiber made by the above method has a polygonal cross-section, which can effectively reduce the gap between the side walls and improve the filling rate. In addition, the refractive index of the polygonal gradient refractive index fiber has a gradient distribution from the center to the edge. Incident light at different incident angles propagates forward in the polygonal gradient refractive index fiber according to a sinusoidal law. The light transmission process repeats according to a fixed periodic pattern. If The period is recorded as P. When the length L of the polygonal gradient refractive index fiber is 0.25P, and collimated light is incident from one end, the light will automatically focus on the other end face; if the length of the polygonal gradient refractive index fiber is an integer multiple of the half period, For example, 0.5P, 1P, 1.5P, 2P, the light emerges as parallel light. Polygonal gradient refractive index fibers can be used to achieve functions such as light collimation or image transmission.

A method for preparing a polygonal gradient refractive index lens array, based on the method for preparing polygonal gradient refractive index fibers, also includes: 6) arranging several polygonal gradient refractive index fibers into an array according to a polygonal cross-section to form a polygonal gradient refractive index fiber array rod;

It further includes: 7) melting and forming the polygonal gradient refractive index fiber array rod in a melting and pressing furnace at 750-850°C. Through this melt-pressing molding, the gaps between the polygonal gradient refractive index fibers can be removed to form a polygonal gradient refractive index fiber array mother rod; the polygonal gradient refractive index fiber array mother rod is cut according to the optical imaging design length; both end surfaces are polished to make Polygonal gradient index lens array.

The polygonal gradient refractive index fiber array rod is drawn twice, and the secondary drawing is arranged into a polygonal array again for three times of drawing until a polygonal gradient refractive index fiber array with a preset diameter and a single core diameter is formed. This step can be repeated as needed, re-arranged after drawing, and then drawn again to obtain the desired array specifications.

It has the following characteristics: 1) Each unit pixel is a polygon, which reduces the triangular gap that exists when stacking between pixels; 2) The unit pixel is a gradient refractive index material, which does not require cladding and can be directly used for light processing. transmission; 3) Using a new glass system, it is easy to produce polygonal gradient refractive index fibers.

Description of the drawings

Figure 1. Schematic diagram of the axis light transmission trajectory and cross-sectional refractive index distribution of a polygonal gradient refractive index fiber lens;

Figure 2. Schematic diagram of the structure and cross-sectional refractive index distribution of the quadrilateral gradient refractive index fiber lens array;

Figure 3. Schematic diagram of the structure and cross-sectional refractive index distribution of a hexagonal gradient refractive index fiber lens array.

Detailed ways

The present application will be further described below in conjunction with the accompanying drawings and examples:

Embodiment 1

A cesium-containing glass made from a compound including: 42% Cs ₂ O, 33% SiO ₂ , 6% B ₂ O ₃ , 3% Al ₂ O ₃ , 4% Na ₂ O, 4% K ₂ O , 4% ZnO, 1% ZrO ₂ , 3% InF ₃ .

Embodiment 2

A cesium-containing glass made of a compound including: 49% Cs ₂ O, 25% SiO ₂ , 6% B ₂ O ₃ , 4% Al ₂ O ₃ , 4% Na ₂ O, 1% K ₂ O , 4% ZnO, 2% ZrO ₂ , 5% InF ₃ .

Embodiment 3

A method for preparing quadrilateral gradient refractive index fibers, 1) mixing each compound into a batch;

2) Smelt the cesium-containing glass in a platinum crucible at a temperature of 1380-1420 degrees, and shape it into a cylindrical glass with a diameter of 60mm; 3) Process the cylindrical glass into a quadrilateral cylindrical glass with a cross-section of 30mm×30mm×450mm. The side walls of the columnar glass are all polished;

4) Place the quadrilateral cylindrical glass on a drawing machine and draw it into a continuous quadrilateral glass fiber with a side length of 1mm and a length of 500mm;

5) Place the quadrilateral glass fiber into molten potassium nitrate salt at 560°C for Cs ⁺ -K ⁺ ion exchange to form a gradient distribution in which the refractive index of the cross section gradually decreases from the center to the edge.

After cutting off a certain length and polishing both ends, it can be processed into a quadrilateral gradient refractive index fiber lens. Its light trajectory and refractive index distribution are shown in Figure 1. Incident light at different incident angles moves forward in the gradient refractive index fiber lens according to the sinusoidal law. Transmission; if the length is 0.25P and collimated light is incident, the light will automatically focus on the end face; if the length is close to 0.5P, 1P, 1.5P, 2P and other integer half-period lengths, the light will emerge as close to parallel light.

Embodiment 4

Based on Example 3, a method for preparing a quadrilateral gradient refractive index lens array also includes:

Step 6) Arrange the quadrilateral gradient refractive index fibers into an array according to the cross-section quadrilateral. After arranging into the array, the array cross-sectional side length is 25mm and the array length is 500mm; melt and press the polygonal gradient refractive index fibers in a melting furnace at 800°C to remove the polygonal gradient refractive index fibers. The gaps between them form a quadrilateral gradient refractive index fiber array mother rod.

Cut the quadrilateral gradient refractive index fiber array mother rod into a length of 0.5P-0.75P, and polish both ends to form a quadrilateral gradient refractive index fiber lens array as shown in Figure 2 that can perform 1:1 upright imaging. The refractive index The distribution changes in the cross-section according to the periodic parabolic law.

Embodiment 5

Based on Embodiment 4, a method for preparing a quadrilateral gradient refractive index fiber array further includes the steps:

7) Arrange the quadrilateral gradient refractive index fibers into an array according to the cross-sectional quadrilateral. After arranging into the array, the cross-sectional side length of the array is 20mm and the array length is 500mm. The arranged quadrilateral array is processed twice on a wire drawing machine with a drawing furnace temperature of 760°C. Drawing, draw into a quadrilateral glass filament with a side length of 2mm and a length of 500mm. After the second drawing, rearrange the quadrilateral glass filaments into a quadrilateral array with a cross-sectional side length of 20mm and a length of 500mm, and then draw it three times to make a quadrilateral glass filament with a side length of 10 microns. Arrange the secondary drawing into a polygonal array again and perform three drawings until a quadrilateral gradient refractive index fiber array with a cross-sectional side length of 4 mm and a single-pixel core cross-sectional side length of 3-5 microns is formed. This step can be repeated as needed, re-arranged after drawing, and then drawn again to obtain the desired array specifications.

Embodiment 3 to Embodiment 5 are only specific application examples of the present invention. Hexagonal gradient refractive index fiber arrays as shown in Figure 3 or gradient refractive index fiber arrays of other shapes can also be produced as needed.

Claims (9)

1. The preparation method of the polygonal gradient refractive index fiber is characterized by comprising the following steps of:

1) Mixing all the compounds containing cesium glass to prepare a batch; the cesium-containing glass is prepared from the following compounds in percentage by weight: 40% -60% Cs ₂ O；25%-40%SiO ₂ ；5%-10%B ₂ O ₃ ；3%-8%Al ₂ O ₃ ；3%-9%ZnO；5%-10%Na ₂ O+K ₂ O；0.5%-2%ZrO ₂ ；3%-5%InF ₃ ；

2) Melting cesium-containing glass in a platinum crucible at the temperature of 1380-1420 ℃, and discharging from a furnace to form cylindrical glass;

3) Processing the cylindrical glass into polygonal cylindrical glass with a cross section, and polishing the side wall surface of the polygonal cylindrical glass;

4) Drawing the polygonal columnar glass into continuous polygonal glass fibers on a drawing machine;

5) Placing the polygonal glass fiber into 500-600 ℃ potassium nitrate molten salt for Cs (carbon fiber) ⁺ -K ⁺ Ion exchange to form a polygonal gradient index fiber with a gradually decreasing refractive index from the center to the edge.

2. The method for preparing the polygonal gradient refractive index fiber according to claim 1, wherein the cesium-containing glass ingredients comprise: 42% -55% Cs ₂ O；25%-33%SiO ₂ ；6%-8%B ₂ O ₃ ；3%-5%Al ₂ O ₃ ；4%-6%ZnO；5%-8%Na ₂ O+K ₂ O；1%-2%ZrO ₂ ；3%-5%InF ₃ 。

3. The method for preparing the polygonal gradient index fiber according to claim 1, wherein: the number of sides of the polygon is as follows: 2 (n+1), where n is a natural number.

4. The method for preparing the polygonal gradient index fiber according to claim 1, wherein: the diameter of the cylindrical glass is 50-70 mm, the length of the polygonal cylindrical glass is 300-600 mm, and the side length of the cross section is 15-35 mm.

5. The method for preparing the polygonal gradient index fiber according to claim 1, wherein: and arranging a plurality of polygonal gradient refractive index fibers into an array rod according to a cross-section polygonal mode.

6. A preparation method of a polygonal gradient refractive index lens is characterized by comprising the following steps: the polygonal gradient index fiber lens prepared by the method for preparing the polygonal gradient index fiber according to claim 1 is manufactured by cutting the polygonal gradient index fiber according to a preset length and polishing two end faces.

7. A preparation method of a polygonal gradient refractive index lens array is characterized by comprising the following steps: placing the array rod prepared by the polygonal gradient refractive index fiber preparation method of claim 5 into a melting furnace at 750-850 ℃ for melting and pressing to form a polygonal gradient refractive index fiber array master rod, cutting the polygonal gradient refractive index fiber array master rod according to the optical imaging design length, and polishing two end faces to obtain the polygonal gradient refractive index lens array.

8. A preparation method of a polygonal gradient refractive index fiber array is characterized by comprising the following steps: the array rod prepared by the preparation method of the polygonal gradient index fiber in claim 5 is subjected to secondary drawing, and the secondary drawing is rearranged into a polygonal array for three times of drawing until the whole polygonal gradient index fiber array with the preset diameter and the single core preset diameter is formed.

9. A polygonal gradient index fiber produced by the process of producing a polygonal gradient index fiber of claim 1.