CN101251623A - Fusion splicing device and method for photonic crystal fiber - Google Patents

Abstract

The invention discloses a welding device for photonic crystal fiber and a method thereof. A frequency controller (13) of a carbon dioxide laser modulating unit (8), a stress sensor demodulating unit (11) and a three-dimensional alignment controller and a clamp control unit (10) are connected with a processing and control element (9) of the welding device; mechanical transmission mechanisms of a lower three-dimensional motion V-shaped groove device (2) and an upper three-dimensional motion V-shaped groove device (5) are connected with the three-dimensional alignment controller and the three-dimensional alignment controller of the clamp control unit (10); the carbon dioxide laser modulating unit (8) transmits laser to a fiber output point (4) through a transmitting energy fiber (16) to weld a welded fiber (3). The method comprises the following steps of: 1) selecting a welding parameter according to information of a fiber structure; 2) adjusting a clamping force of the V-shaped groove clamp by using the information of the fiber structure; 3) performing a three-dimensional alignment to two fibers to be welded; 4) modulating a carbon dioxide laser by a frequency modulator with a set frequency to transmit laser to the position of welded fibers for welding through the transmitting energy fiber. The welding device for the photonic crystal fiber has the advantages of simple structure, strong capability of anti-interference of vibration, high sensitivity and easy manufacture, and is suitable for welding between photonic crystal fibers with different specifications and between the photonic crystal fiber and a conventional optical fiber.

Description

Fusion splicing device and method for photonic crystal fiber

technical field

The invention relates to the technical field of photonic crystal fiber fusion, in particular to a photonic crystal fiber fusion splicing device and method thereof.

Background technique

Photonic crystal fiber came out in the UK in 1996. This kind of fiber has many singular characteristics that ordinary fibers do not have, such as high nonlinearity, controllable dispersion, high birefringence, infinite single-mode characteristics, etc., and can be widely used in In the fields of communication, imaging, spectroscopy and biomedicine, its performance research and application development have always been a hot spot in the international optoelectronics industry. However, the photonic crystal fiber fusion splicing technology is still immature and still in the exploratory research stage, and has become a practical problem that must be solved in the application and development of photonic crystal fiber.

Existing ordinary optical fiber fusion splicers and polarization-maintaining optical fiber fusion splicers cannot automatically complete the fusion splicing of photonic crystal fibers with high quality. The main problems are: 1. It is easy to cause the collapse of air holes in the cladding of photonic crystal fibers during fusion; 2. 1. Bubbles are easy to be generated when welding large-aperture optical fibers; 3. Accurate control of welding energy cannot be realized.

At present, there are also studies on the use of carbon dioxide lasers to weld photonic crystal fibers. This method has the advantages of being able to precisely control the center position of the laser beam and the laser power, and does not leave any residue in the welding part. It can reduce the collapse of the air holes in the fiber cladding and reduce the Splice loss, but the research of this method only conducts experimental research on a specific optical fiber, and cannot control the energy distribution at different radial positions of the photonic crystal fiber, and it is difficult to control the collapse of cladding air holes during the splicing process .

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a photonic crystal fiber fusion splicing device and its method, which can realize the energy control of the photonic crystal fiber fusion splicing process, thereby controlling the collapse of the air holes in the cladding of the optical fiber, high quality The fusion splicing between photonic crystal fiber and conventional fiber and between photonic crystal fiber and photonic crystal fiber is completed.

The technical solution adopted by the present invention to solve its technical problems is: the fusion splicing device and method thereof for this photonic crystal fiber, including two parts:

The fusion splicing device of the photonic crystal fiber includes a modulation carbon dioxide laser unit 8, a three-dimensional motion V-groove device (2, 5), a stress sensor demodulation unit 11, a three-dimensional alignment controller and a clamp control unit 10, and a processing control unit 9 . The processing control unit 9 of the device is connected to the frequency controller of the modulation carbon dioxide laser unit 8, the stress sensor demodulation unit 11, the three-dimensional alignment controller and the fixture control unit 10 to realize the control of the above units and the acquisition of stress information. The mechanical transmission mechanism of the three-dimensional motion V-groove device (2, 5) is connected with the three-dimensional alignment controller and the three-dimensional alignment controller of the fixture control unit 10, and the processing control unit 9 controls the three-dimensional alignment controller to realize Alignment of fibers. The processing control unit 9 controls the optical fiber clamp through the three-dimensional alignment controller and the clamp control unit of the clamp control unit 10 to clamp the optical fiber. The lower and upper stress sensors (1, 7) sense the clamping force in real time, and the lower and upper stress sensors (1, 7) sense the clamping force in real time. The stress sensors (1, 7) are connected to the stress sensor demodulation unit 11, and the magnitude of the force is fed back to the processing control unit 9 for further adjustment of the clamping force, so as to complete the control of the magnitude of the clamping force in a closed loop. The modulated carbon dioxide laser unit 8 transmits the laser light to the optical fiber to be melted 4 through the energy transmission optical fiber 16 . The device realizes the three-dimensional control of the optical fiber to be fused through the three-dimensional movement device, and realizes the modulation of the laser through the modulation controller, so as to control the energy, wavelength and welding time of the laser, so as to realize the energy, wavelength and welding time of different specifications of photonic crystal fibers during the welding process. The allocation of control the collapse degree of the photonic crystal fiber cladding air hole during the fusion splicing process to achieve low-loss splicing.

The fusion splicing method of the photonic crystal fiber is: clamping the fused lower and upper photonic crystal fibers (3, 6) in the V-groove fiber clamp of the three-dimensional motion V-groove device (2, 5) of the fusion splicing device . Afterwards, the end face structure information of the photonic crystal fiber before fusion is obtained through the three-dimensional microscopic imaging device. The information selects welding parameters, and the welding parameters include modulation frequency, laser wavelength, laser power, welding time, welding times, and the like. Use the obtained photonic crystal fiber end face structure information to determine its maximum bearing force, and then adjust the clamping force of the V-groove fiber clamp so that it can be clamped well without destroying the structure of the air hole in the fiber cladding . After the photonic crystal fiber is clamped, three-dimensional alignment is performed on the two fibers to be fused; after alignment, parameters such as energy required for fusion, fusion time, and modulation frequency of the modulator are determined according to the acquired fiber end face structure information. Modulate the carbon dioxide laser with a modulator with a set output frequency, split the output of the carbon dioxide laser 14 into three identical laser beams through the one-to-three optical coupler 15, and transmit the light to the fiber output point 4 pairs of laser beams through the energy-transmitting optical fiber 16. Fused optical fiber 3 is fused.

The modulation controller 13 is completed by using the integrated circuit FPGA XC3S500E to generate modulation signals of different frequencies and control the output power of the laser.

The optical coupler 15 is used to complete the optical coupling between the laser and the energy transmission fiber. The light output by the laser is adjusted into a parallel laser beam with uniform energy distribution through the optical device in the optical coupler 15, and the three energy transmission fibers 16 are evenly arranged in the parallel laser beam, so that the laser is evenly coupled into the energy transmission fiber 16.

The processing control unit 9 is composed of a SEED-Davinci digital platform, which integrates dual-core ARM9+DM64X, has the characteristics of digital image processing function and real-time control ability, and intelligent control and calculation analysis are completed by it.

The beneficial effects of the present invention are: adopting the carbon dioxide laser as the welding energy source can avoid leaving any pollution and residue in the welding part, avoiding the fragility of the welded optical fiber, and can precisely control the beam shape, center position and output power; The controller modulates the carbon dioxide laser, and the distribution of energy in the fiber to be fused can be realized by changing the modulation frequency; the end face information of the fiber to be fused is obtained by using a three-dimensional microscopic imaging system, and different fusion splicing mathematical models are selected according to the different structural parameters of the end face, so as to select Appropriate parameters such as splicing power, modulation frequency and splicing time; can control the collapse of the fiber cladding air to the greatest extent and minimize the splicing loss. The invention has the advantages of simple structure, strong anti-vibration interference ability, high sensitivity and easy manufacture, and is suitable for fusion splicing between photonic crystal fibers of the same type and photonic crystal fibers of different types.

Description of drawings

Fig. 1 is the structural representation of the fusing device of photonic crystal fiber;

Fig. 2 is a schematic diagram of a V-groove structure;

Fig. 3 is a structural schematic diagram of a modulated laser;

Fig. 4 is a schematic diagram of the geometric structure of the photonic crystal fiber end face.

In the above drawings, 1. the lower stress sensor, 2. the lower three-dimensional motion V-shaped groove device, 3. the lower photonic crystal fiber, 4. the output point of the energy transmission fiber, 5. the upper three-dimensional motion V-shaped groove device, 6. the upper Photonic crystal fiber, 7. Upper stress sensor, 8. Modulation carbon dioxide laser unit, 9. Processing control unit, 10. Three-dimensional alignment controller and fixture control unit, 11. Stress sensor demodulation unit, 12. Optical fiber fixture, 13. Frequency controller, 14. Carbon dioxide laser, 15. Optical coupler, 16. Energy transmission fiber, 17. The radius from the center of the fiber core to the air hole layer, 18. The center of the fiber core, 19. The outer cladding of the fiber, 20. The air hole of the fiber Layer, 21. The radius from the center of the core to the outer cladding, 22. The radius of the core.

Detailed ways

Example

1. The specifications of the fusion-spliced lower and upper photonic crystal fibers (3, 6) are: the mode field radius is 7.5 μm, the core diameter is 10.9 μm, the hole spacing is 3 μm, the air hole diameter is 2 μm, and the number of air hole layers is 6 layers . Install the fused lower and upper photonic crystal fibers (3, 6) on the lower and upper three-dimensional motion V-groove devices (2, 5).

2. According to the structural parameters of the lower and upper photonic crystal fibers (3, 6), pass through the lower and upper stress sensors (1, 7), the stress sensor demodulation unit 11, the three-dimensional alignment controller and the fixture control unit of the fixture control unit 10 The feedback control of the optical fiber clamp 12 automatically adjusts the clamping force of the lower and upper photonic crystal fibers (3, 6). The maximum pressure that this kind of photonic crystal fiber can withstand is 0.09N/μm. The clamping force used in the embodiment It is 0.05N/μm, which can prevent the photonic crystal fiber from being damaged during the clamping process, and at the same time ensure that the lower and upper photonic crystal fibers (3, 6) can move relative to each other in three-dimensional space.

3. Realize the three-dimensional alignment of the lower and upper photonic crystal fibers (3, 6) under the processing of the processing control unit 9, by analyzing the end face structures of the lower and upper photonic crystal fibers (3, 6) (see Figure 4) According to the parameters of photonic crystal fiber core, cladding air hole, outer cladding radius, cladding air hole size, layer number, and hole spacing, the laser beams required for the fusion spliced lower and upper photonic crystal fibers (3, 6) are obtained , energy, modulation frequency and other parameters, for the photonic crystal fiber in this embodiment, the laser power to be applied is 10W, the modulation frequency varies between 50-100Hz according to the time of each welding, and the beam diameter is about 500-600μm The process control unit 9 controls and modulates the carbon dioxide laser unit 8 to fuse the lower and upper photonic crystal fibers (3, 6). Use the frequency controller 13 to set the output frequency to modulate the carbon dioxide laser 14, and the output of the carbon dioxide laser 14 is divided into three identical laser beams through the one-to-three optical coupler 15, and the light is transmitted to the three beams through the energy transmission fiber 16. The optical fiber output points 4 are spliced, and the three optical fiber output points 4 are distributed at an angle of 120° (see FIG. 3 ). The modulation carbon dioxide laser unit 8 just can control the energy transfer of the laser output energy in the lower and upper photonic crystal fibers (3, 6) by changing the modulation frequency of the frequency controller 13, so that the temperature of the photonic crystal fiber core and the outer cladding is higher than that of the air hole The temperature of the layer is higher, and at the same time, the temperature distribution time of the air hole layer can be controlled, thereby controlling the degree of deformation of the air hole when splicing the photonic crystal fiber.

4. After selecting the parameters, start to weld the optical fiber. First, use the beam with a modulation frequency of 50Hz to irradiate directly and continuously for 1s to remove the impurity particles on the fiber; then use the beam with a modulation frequency of 80Hz to irradiate 3 times, each time for 2s; Finally, the light beam with a modulation frequency of 50 Hz was continuously irradiated for 1 second to remove impurities after welding, and the final measured welding loss was 0.05 dB.

Keep the laser power and beam size unchanged, change the modulation frequency of the laser to 150Hz, perform fusion splicing on the same optical fiber, and still use the beam with a modulation frequency of 50Hz to irradiate directly for 1s to remove the impurity particles on the optical fiber.

Then use a beam with a modulation frequency of 150Hz to irradiate 3 times, each time for 2s; finally, use a beam with a modulation frequency of 50Hz to irradiate continuously for 1s to remove impurities after welding. Large, by observing the image of the welding point, the welding caused the air holes in the cladding to collapse to a large extent, which is the main reason for the excessive loss of the welding.

Claims (8)

1. the fusion splicing devices of a photonic crystal fiber is characterized in that: processing and control element (PCE) (9) is connected with frequency controller (13), strain gauge demodulating unit (11), three-dimensional alignment controller and the anchor clamps control module (10) of modulation carbon dioxide laser unit (8); Upper and lower three-dimensional motion V-type slot device (2,5) mechanical transmission mechanism is connected with the three-dimensional alignment controller of three-dimensional alignment controller and anchor clamps control module (10), processing and control element (PCE) (9) is connected with the three-dimensional alignment controller of three-dimensional alignment controller and anchor clamps control module (10), realizes the aligning of optical fiber; Processing and control element (PCE) (9) carries out clamping by the anchor clamps control module control fiber clamp of three-dimensional alignment controller and anchor clamps control module (10) to optical fiber; Processing and control element (PCE) (9) is connected with strain gauge demodulating unit (11), and strain gauge demodulating unit (11) and upper and lower strain gauge (1,7) connect; Modulation carbon dioxide laser unit (8) is sent to optical fiber output point (4) to being carried out welding by molten optical fiber (3) by energy-transmission optic fibre (16) with laser.

2. the fusion splicing devices of photonic crystal fiber according to claim 1, it is characterized in that: the signal wire that upper and lower three-dimensional motion V-type slot device (2,5) mechanical transmission mechanism is drawn connects the three-dimensional alignment controller of three-dimensional alignment controller and anchor clamps control module (10).

3. the fusion splicing devices of photonic crystal fiber according to claim 2, it is characterized in that: upper and lower three-dimensional motion V-type slot device (2,5) V-type groove (2) is equipped with strain gauge (3) and optical fiber clamping plate (12), upper and lower photonic crystal fiber (3,6) be clamped in respectively in the upper and lower three-dimensional motion V-type slot device (2,5).

4. the fusion splicing devices of photonic crystal fiber according to claim 1, it is characterized in that: modulation carbon dioxide laser unit (8) is made up of frequency controller (13), carbon dioxide laser (14), photo-coupler (15) and energy-transmission optic fibre (16), one minute three photo-coupler (15) make carbon dioxide laser output be divided into the identical laser of three beams to be transferred to three optical fiber output points (4) by energy-transmission optic fibre (16), three optical fiber output points (4) distribution angle is 120 °.

5. the welding process of the fusion splicing devices of the described photonic crystal fiber of claim 1 is characterized in that: said method comprising the steps of:

1) the upper and lower photonic crystal fiber (3,6) of welding is clamped in the V-type groove fiber clamp of upper and lower three-dimensional motion V-type slot device (2,5) of described fusion splicing devices;

2) three-dimensional microscopic imaging device obtains the structural information of the preceding photonic crystal fiber end face of welding, selects the welding parameter with this structural information;

3) utilize the end face structure information of photonic crystal fiber to determine its maximum holding capacity, adjust upper and lower three-dimensional motion V-type slot device (2 then, the holding force size of V-type groove fiber clamp (12) 5), make its can be very to be held, do not destroy the structure of fibre cladding airport again;

4) after photonic crystal fiber is held, two optical fiber fusion is carried out three-dimensional aim at;

5) determine the modulating frequency parameter of its welding institute energy requirement size, weld time, modulator after aiming at again according to the fiber end face structural information of obtaining;

6) remove to modulate carbon dioxide laser (14) with the frequency controller (13) that configures output frequency, by one minute three photo-coupler (15) make carbon dioxide laser output be divided into the identical laser of three beams, by energy-transmission optic fibre light transmission is carried out welding to melting the optical fiber place.

6. the welding process of modulation type photonic crystal fiber according to claim 5 is characterized in that: described photonic crystal fiber end face structure information comprises size, airport spacing and the airport number of plies of the size of fibre core and shape, covering airport; Select the welding parameter with this structural information, described welding parameter comprises modulating frequency, laser wavelength, laser power and weld time and welding number of times.

7. the welding process of modulation type photonic crystal fiber according to claim 5, it is characterized in that: under the structural parameters of photonic crystal fiber (3) and last photonic crystal fiber (6) pass through down, upper stress sensor (1,7), strain gauge demodulating system (11), the FEEDBACK CONTROL of the anchor clamps control module of three-dimensional alignment controller and anchor clamps control module (10) is adjusted fiber clamp (12) automatically to following, last photonic crystal fiber (3,6) holding force, make its can be very to be held, do not destroy the structure of fibre cladding airport again, can guarantee down again simultaneously, last photonic crystal fiber (3,6) can relative motion in three dimensions.

8. the welding process of modulation type photonic crystal fiber according to claim 5, it is characterized in that: under the processing of processing and control element (PCE) (9), to upper and lower photonic crystal fiber (3,6) carrying out is three-dimensional to be aimed at, aiming at the back passes through upper and lower photonic crystal fiber (3,6) structure analysis obtains welding to the required laser beam of upper and lower photonic crystal fiber (3,6), energy and modulating frequency parameter.

Images