Design and Fabrication of Fiber optic array – A summary

1. Design of fiber array

The fiber array with one-to-one correspondence at both ends is to regularly gather multiple fibers of a certain length into a bundle to achieve an optical device that can transmit light and energy according to the designed transmission mode.

The optical fibers in the array can be regarded as a row of individual optical windows, and they have no effect on the transmission of light between them.

In the independent transmission process, it carries independent energy. The energy depends on the transmission mode and material of the fiber material. The total energy is the number of fibers on the end face multiplied by the energy value transmitted by a single fiber.

Both ends of the array must be arranged in a correlated manner, that is, each fiber is required to have a consistent correspondence between the output and input energy, otherwise a large loss will occur. Therefore, from the perspective of energy conservation, it can also be explained that the outgoing energy and the incoming energy are basically the same.

1.1 V-groove structure and FA (fiber array) package design

At present, the method of developing one-dimensional fiber arrays used in semiconductor lasers at home and abroad is mainly the V-groove method.

This method is to etch V-shaped grooves on a Si substrate with high flatness, and arrange and fix the optical fibers in the V-shaped grooves. This method has good scalability and flexible selection of the number of V-shaped groove channels. From the geometric calculation, the wall thickness of the V-groove, the fiber diameter and the center distance of the V-groove (as shown in Figure 1) can be obtained as shown in the following formula,

d is the center-to-center distance of adjacent V-grooves, and
h is the fiber The distance from the center to the upper edge of the V-groove,
r is the fiber radius.

Fig. 1 The position structure between the optical fiber and the V-groove

In the manufacturing process of the V-groove of the Si substrate, the physical size of the V-groove and the fiber radius determine the upper end width of the lower end angle of the groove, and there is a groove depth X, when the groove depth is greater than or equal to X, the target fiber or array position can be uniquely determined, from which it is derived:

In the design, the FA package scheme adopts Si-Fiber-Si.

For the Si-fiber-Si package, when the diameter of the fiber is very small, two V-shaped grooves can easily fix a group of fibers in order to reduce the accuracy between the cables and reduce the difficulty of operation. Although Si is opaque, For the heat generated by high-energy laser light coupled into or refracted from the fiber, Si is the most suitable heat dissipation material.

The Si-based solution does not have strict requirements on the diameter of the fiber and the curing glue process, so this project adopts this solution to fabricate the array fiber.

After determining the materials of the fiber and Si, we must design the packaging structure, In semiconductor laser coupling, when the core diameter and NA of the optical fiber satisfy the light source, we must also consider the influence of stray light such as reflection and refraction on the coupling device and the entire system. In this experiment, the structure of the bare fiber protruding from the Si end face is adopted in consideration of these, as shown in Figure 2.

Fig. 2 Simulation diagram of optical fiber and Si substrate structure

For the problem of overheating of the device caused by the loss of the laser part, we use zemax for optical simulation, see Figure 3 below.

In a laser module with an output power of 50W, the optical fiber protrudes from the Si substrate by 1.5mm. During the coupling, the power detector detects 0.6W of power on the Si substrate, and detects 2.3W of power on the structural substrate of the same plane as the fiber box substrate.

Fig. 3 Coupling effect diagram of different packaging structures of optical fibers

1.2 Design of the beam combining structure

The beam combining structure is used as the output port after laser coupling, and its energy density is high. Therefore, it is necessary to consider the temperature resistance, heat dissipation method and external port type. Most of the interfaces in the semiconductor laser industry are SMA. Optical glue is required, and heat dissipation must also be considered in the mechanical design part of the connector. See Figure 4 below for the solid works simulation diagram (a is the mechanical appearance of the combined bundle, and b is the ideal model after the optical fiber is combined).

Fig. 4 SMA bundle structure

1.3 Fixed packaging of fiber arrays and bundles

For the selection of the positioning method of the optical fiber material, first, ultrasonically process the V-groove and the optical fiber, then cut the clean optical fiber to the required length and put it into the silicon V-groove in parallel, inject a thermal adhesive with suitable viscosity, and then take the Symmetry is basically pressed by gravity, and the adhesive is cured in a curing oven.

During the operation, attention should be paid to the cleanliness of the environment, because the precision of assembly and bonding requires very high air cleanliness.

These all need to be clearly manifested in the operating instructions, which play a very important role in the life and use of optical fiber devices. The following aspects must be paid attention to:

(1) Good adhesion with Si substrate;
(2) Moderate viscosity, good fluidity and good permeability;
(3) The curing can be completed within the required time, which is convenient for the completion of the subsequent process;
(4) Moderate hardness and high strength, support grinding and polishing of various processes; (5) The product is stable and has good weather resistance;
(6) The curing temperature is moderate, and the strong temperature makes the stress in the curing process unable to be released and affects the quality.

In most fiber arrays, when the adhesive is not cured, the fiber will move due to the influence of external force. These movements will eventually lead to the failure of the array processing, usually for the tilting of the fiber substrate and the curing process. The pressure between the substrates needs to be balanced to ensure the precise location of the bond.

The optical fiber bundle is made by combining several optical fibers, adding a protective sleeve, glueing the two ends into the required interface form, and then grinding and polishing. Its structure is shown in Figure 5.

Fig. 5 Design and assembly diagram of fiber array

To solve the sealing of the optical fiber bundle, the mutual sealing between the optical fibers and the sleeves must be considered. In fact, it is to solve:
①The radial error of the optical fiber relative to the V-groove assembly of the substrate (similar lateral tolerance);
②Vertical engineering of the optical fiber on the V-groove of the substrate (similar lateral tolerance);
③The angle error between the optical fiber and the V-groove. The three need to be coordinated in parallel, and the lack of any one may bring about the failure of the process. Therefore, we have studied the sealing principle, bonding process and detection method of the combined optical fiber.

The essence of the bonding of the combined fiber is to solve the sealing problem between the optical fiber and the optical fiber in the optical fiber bundle, and between the combined bundle and the sheath.

When the optical fiber bundle is in use, as a device connecting the inside and outside of the sealing system, there is a pressure difference. If there is a pressure difference between the inside and outside of the system, if there is a micro-hole, micro-crack or cavity between any two of the three contact places, that is, When there is pressure, the optical fiber will be stretched or even broken. The following figure can be simply expressed:

Fig. 6 Schematic diagram of optical fiber sealing pressure

Of which:
P1——Maximum pressure of fiber bundle after bonding, MPa;
P——Internal pressure of bonding system, MPa;
Po——The pressure outside the bonding closed area, usually atmospheric pressure, MPa.

As shown in the figure above, there are 3 types of bonding and sealing areas for fiber bundles:
①To achieve the sealing of both ends of the fiber bundle, because the fiber array is completed under the pressure of P0, then its force P0, the fiber array will be sealed when P1 ≥ |P-P0|.
②The other end of the fiber bundle is in a free state, and the other end is bonded. In this case, the pressure is still P0. Similarly, only if P≥|P−P0| is satisfied, the sealing of the fiber array can be ensured.
③If it is bonded outside the bonding system, because of the leakage of the coupling end of the optical fiber bundle, the internal pressure is the bonding pressure P, so to achieve sealing, the necessary condition is to satisfy P1≥P-P0.

It can be seen that the most economical way to solve the sealing of the fiber bundle is: on the basis of no waste, and without affecting the physical properties of a single fiber, one end is used as the free end, and the other end is bonded, so that the fiber will not be affected by the problems occur due to external forces that are greater than their own tolerance.

Grinding and polishing

Polishing is a very important link in the process of fabricating high-precision one-dimensional linear fiber arrays. It has a great influence on the coupling accuracy of the device, mainly due to the quality of the fiber end face.
The purpose of grinding and polishing is to remove unevenness, crack damage and pit pollution on the surface of the optical fiber, making it smooth, delicate, and capable of high-precision three-dimensional geometric dimensions.
In this subject, the end face polishing of the optical fiber array is realized by the mechanical polishing method. The selection of the grinding and polishing process parameters of the two end faces of the optical fiber array has a great influence on the quality of the optical fiber array device. It also affects the transmission quality of light.

(1) FA end grinding design
At the end of the optical fiber array, there is a bare optical fiber with a length of 1.5 mm protruding from the plane of the silicon substrate, which greatly increases the difficulty of grinding, especially traditional mechanical grinding.
To ensure the flatness of the optical fibers in the array, it is necessary to design and process precise clamping and grinding fixtures, as shown in Figure 7.

Fig. 7 Fixture design

Multi-chip processing technology can improve production efficiency and reduce production costs. It is also easier to master than single-chip processing in terms of mechanical precision control requirements, and can achieve higher precision indicators.

Because if the processed end face of the optical fiber is not perpendicular to its optical axis, the end face will be inclined or wedged. As the fiber receiving end, when the incident angle of the laser beam and the normal direction of the processed end face are in the same direction as the optical axis of the receiving (processed) fiber, the numerical aperture of the processed fiber is:

n1 is the refractive index of the fiber core,
n2 is the refractive index of the fiber cladding,
α is the beam acceptance angle and
β is the processing tilt angle of the processing fiber.

It can be seen from the above formula that, combined with the previous explanation, the coupling can be completed only when the light beam with an incident angle of α is received and its numerical aperture is larger than the receiving aperture of the machined end face.
When the direction of the incident angle of the light beam and the normal of the processed end face are on both sides of the optical axis of the fiber, the situation is just contrary to the result obtained by the above formula.

(2) SMA end grinding design
The SMA end is the bundling end of the fiber, which has a very important influence on the spectral characteristics of the received light and the coupled laser.
Because if the outgoing end face of the outgoing laser beam has an inclined angle, the deflection angle of the outgoing light cone itself will also be caused. Therefore, when grinding and polishing the end face of the optical fiber bundle, the perpendicularity between the processed end face and the central axis of the optical fiber is first ensured.

(3) Optical fiber end face grinding and polishing quality design
In conductor coupling technology, the matching of the mode field between the fiber and the laser is equivalent to the function of the fiber as a connector in most cases.
The impact of end face quality on fiber coupling efficiency is reflected in the requirements of the international standard IEC for fiber optic connectors. As a connector, the first is optical transmission performance, interchangeability and repeatability. Optical performance, mainly insertion loss and return loss.

Insertion loss and insertion loss refer to the loss of light energy caused by the connector during use.

The smaller the insertion loss value, the better, generally around 0.5dB.

Return loss (Return Loss, Reflection loss) refers to the ability of the target connection device to resist the feedback of optical power under the light guide, and its typical value is 20-25dB.

In the practical application of the connector, the surface of the pin has been specially polished, plated with high-transparency optics, and treated with a thin film to improve the level of return loss, which is generally greater than 50dB.

Pluggable: Interchangeability in semiconductor lasers can also be called pluggability. Optical fiber connectors, as passive components, are also required to be able to combine and replace the same type of optical fiber connectors at will. Repeated connection, disassembly and use, the additional loss introduced by this is generally within the range of 0.2dB.

The requirements for various losses of optical fiber devices in these international standards are suitable for the communication field and also for laser coupling. In laser coupling, the industry rule is that the loss ratio of the end face of the connecting device after processing, grinding and polishing is less than 4% of the coupling power.

2. Research on the processing technology of fiber array

2.1 Technological test process and analysis of fiber array

It can be seen from the fiber array design that the fiber array structure that meets the requirements of semiconductor laser coupling consists of three parts, and the process of the FA end is the basis of the device process.
Prepare the required optical fiber and the designed V-groove for assembly and curing (as shown in Figure 8).

Fig. 8

When installing the fiber array into the fixture, ensure that the fiber axis is perpendicular to the fixture. When grinding the array end, pay attention to the arrangement of the free fibers at the other end to avoid touching the fibers (see Figure 9).

Fig. 9

Grinding pads are generally made of glass plates with high flatness and smoothness or other hard materials as the bottom. Before the grinding process starts, spray a small amount of water on the backing plate, then spread the abrasive sandpaper evenly, and use a soft brush to remove the air bubbles between the grinding sandpaper and the bottom of the grinding backing plate, so that the sandpaper is firmly attached to the bottom of the backing plate. on (see Figure 10)

Fig. 10

During grinding, you need to spray a small amount of water on the sandpaper to wash away the debris left by grinding. Prevents the risk of poor product grinding due to residual debris during cyclic grinding (see Figure 11).

Fig. 11

The ground FA end is temporarily and effectively protected to prevent particle dust contamination and the damaging effects of other processes (see Figure 12).

Fig. 12

Of course, the packaging and grinding of the SMA end of the coupling device are the keys to the array process. It is also the most difficult to process and requires the highest precision in appearance size.
Use an air gun to clean the inner hole of the ferrule tail, and then install the hexagon nut, C-type snap ring, gold-plated ceramic ring and rubber ring in sequence from the pin tail, as shown in Figure 13.

Fig. 13

Stir the glue evenly and defoaming. Dip the glue with a glue stick and pour it into the inner hole of the pin from the tail. Do not fill the pin, leave a distance of about 1-2mm, as shown in Figure 14.

Fig. 14

Insert the optical fiber into the ferrule with light force when inserting the needle to prevent the optical fiber from breaking, as shown in Figure 15. Control the length of the device, including the length of the exposed fiber at the front end of the pin.

Fig. 15

The jig was placed on a heating table and heated at 60°C for 1 hour, then at 90°C for 1 hour, and finally at 110°C for 1 hour (Figure 16). Turn off the power of the heating table, and after the temperature returns to normal temperature, remove the device and put a dust cap on the FA end.

Fig. 16

Put the SMA905 end into the grinding jig. The devices should be placed symmetrically on the jig. The FA end of each device should be equipped with a dust cap. Try not to touch the FA end during operation, as shown in Figure 17.

Fig. 17

Put the grinding jig on the grinding machine and start rough grinding. After the rough grinding is completed, replace the grinding pad and polishing flannel, and perform rough grinding, fine grinding and polishing in sequence. The effect after completion according to the process parameters is shown in Figure 18.

Fig. 18

The process parameter design is shown in the table 1.

Table 1 Process parameter design

wdt_ID Step Abrasive paper type Add liquid to abrasive paper Grinding time Polishing pad type
1 Coarse grinding 9um diamond Deionized water 2 minutes Glass polishing pad
2 Finely ground 3um diamond Deionized water 3 minutes Glass polishing pad
3 Polishing Polishing flannel Polishing liquid 15 minutes Rubber polishing pad

Time parameter design control as shown in Figure 19.

Fig. 19 Time modulator

Regularly replace the abrasive sandpaper to ensure the consistency of the grinding experiments. As the number of times of grinding sandpaper increases, its grinding efficiency and stability will decrease, and the grinding sandpaper will also have different lifespans due to different experimental requirements and quality parameters. As you increase the grinding pressure and increase the grinding speed (not recommended), the life of the abrasive paper will decrease.
Grinding tools and fixtures must be cleaned regularly. In order to ensure the flatness of the tools, they will not be deformed due to long-term pollution.

2.2 Experiment and result analysis

The diamond particle size of the abrasive sandpaper obviously affects the surface roughness during processing. As the diamond particle size of the sandpaper is smaller, the scratches formed by the abrasive particles on the product are smaller, and the length and width of the cracks on it gradually become smaller. , the roughness of the machined surface is bound to become smaller.

Therefore, we use diamond sandpaper with a diamond particle diameter of 9V for grinding. Under the condition of the self-weight of the grinding pressure fixture, the grinding time is 90s. The quality of the fiber end face after grinding is shown in Figure 20.

Fig. 20

Figure 20(a) shows that the end face of the optical fiber obtained by grinding with diamond sandpaper with a particle size of 9µ is very rough.
The surface is uneven under the microscope, and the microfacet blocks and cladding crystals are stretched or broken, indicating that the fiber material is removed in the extrusion fracture mode.

Figure 20(b) is the grinding sandpaper with a flat particle size of 3µ. The end face obtained is also relatively rough, and there are dull raised particles on the surface, and there are small bright spots on the machined surface relative to the picture a.
In this process, we can see that the removal of the optical fiber is relatively stable, and there is no destructive extrusion. This process is called semi-extrusion brittleness.

Figure 20(c) shows the surface of the optical fiber obtained by grinding with abrasive paper with an average particle size of 1µ. The end face is basically free of serious pits, bumps and flaws, which indicates that the fine-grained abrasive makes the surface of the optical fiber end removed during grinding. The process is continuous, and this change makes the unevenness on the surface of the optical fiber flattened by continuous extrusion, and realizes the processing effect of removing excess material in the plane to achieve smoothness.

In the above analysis, the particle size of the sandpaper obviously affects the grinding efficiency. In order to increase the grinding removal amount and improve the grinding efficiency, the larger particle size can be selected to grind the sandpaper.

Of course, limited by the material removal and grinding mechanism during grinding, mechanical cracks will be generated and expanded. Therefore, if the particle size is larger, the removal efficiency will be improved, and the mechanical cracks will also expand and increase.
Therefore, for the selection of abrasive paper, it is best to reduce the particle size of the abrasive paper in a step-like manner to conduct the grinding test. The particle size of the abrasive paper is from large to small, and the equipment performs rough grinding at low speed, and then changes several times. The sandpaper is used for fine grinding, and finally, the sandpaper or polishing pad with small particle size is used for polishing, so that the optical fiber end surface has a good finish after grinding.

For large-grained sandpaper, if the speed of selecting the equipment is relatively fast, the optical fiber grinding end face will be rougher, and the loss of the sandpaper will be relatively large. The choice of fine sandpaper grinding speed is relatively slow, which wastes grinding time.

From the above content, it can be seen that the choice of grinding sandpaper is very important in the grinding process, which directly determines the grinding effect of the fiber end face.
Therefore, design the grinding speed, control the matching of a certain speed and time according to experience, and arrange the replacement of sandpaper in order of particle size. Such design work must be carried out before grinding.
When grinding sandpaper with a certain particle size, it is also necessary to regularly correct the relative position of the contact between the optical fiber and the grinding disc, so as to avoid the grinding time of the sandpaper is too long, the surface particles will be damaged and fail, and the grinding effect will be destroyed.
In addition, it should be noted that after each process is completed, the end face of the optical fiber connector that has just been ground must be rinsed with clean water, otherwise the grinding quality will be reduced and the life of the next grinding sandpaper will be affected.

Choice of processing time

After the particle size is selected, the grinding and polishing time is another important parameter in the optical fiber device end face processing process. The grinding and polishing needs to go through three important processes: rough grinding, grinding, and fine grinding.
Among them, rough grinding, grinding, and fine grinding refer to the grinding paper with different particle sizes of the grinding sandpaper used for grinding, which are 9µ, 3µ, and 1µ particles respectively. When the next process is performed, other conditions remain unchanged. As long as the processing time is changed, products with different end face qualities can be obtained.

In order to obtain the most scientific and efficient processing technology combination, we select the time parameter as a variable, and the following experimental results can be obtained.

The pressure here refers to the air pressure, the unit is MPa, and the time unit is seconds. In the experiment, new grinding sandpaper was used, and the number of FAs for each grinding was 9 pieces. The experimental plan is shown in Table 2-1:

Table 2-1 Processing time plan record table

The quality of the processing is judged by the effect displayed by the test instrument. From the above table data and statistical analysis of the defect status, each group of defects is shown in Table 2-2 of the yield transition, and it is obvious that the sixth group of data is the best.

Table 2-2

In the processing of optical fiber arrays, because of the greater instability and relatively strict condition requirements compared with single-filament fiber processing,
Therefore, in the processing of the array, if the process allows, the number of changing parameters directly affects the controllability of the process.
Therefore, in this case, we only discuss the processing surface of the optical fiber under different conditions of time and abrasive paper particle size. The two parameters most bring about the occurrence of the following four kinds of defects, as shown in Figure 21.

Fig. 21

(1) End face depression

Since the hardness of the optical fiber is smaller than that of the general matrix (or the pin), when the result of the combination of grinding pressure and time exceeds a certain fixed value, end face depression will appear. Due to the indentation of the optical fiber relative to the silicon base, interference fringes are formed. The interference fringes are optical ripples, which appear to shift toward the center of the circle under the microscope, as shown in Figure 21(a).

(2) Fracture

When cutting the optical fiber leaking out of the substrate or the end face of the ferrule, due to the shearing force of the optical fiber, the uneven depth of the crack will cause a recessed crack on the end face of the optical fiber after grinding. due to the difference in reflected light. These images appearing on the microscope may be uneven in color on the circular surface, with one half brighter obviously and the other darker, see Figure 21(b).

(3) Scratches

Because the fiber end face has deep cracks or end face defects caused by processing and grinding, in order to clearly observe the bright and dark stripes with distinct clear colors and the color of the entire circular surface on the microscope image, see Figure 21 (c ).

According to the international end face quality inspection standards for optical fiber connectors, the polished optical fiber end faces are screened, and the quality pass rate of the connector is judged through analysis and comparison.

The above experiments show that the first group of experiments results in the appearance of chipping cracks and micro-cracks in the core area, indicating that the selection of processing parameters in this group is unreasonable. In the second group, there are contamination points or defect points, and the individual defect points are larger, and the insertion loss actually increases, indicating that the polishing time is not enough. Although the quality of the processed end faces of the third group is relatively improved, there are still slight scratches, indicating that the grinding time is too long and the polishing time is relatively insufficient. Finally, the fourth group found the best effect, and then changed the process time configuration, and finally obtained the optimal configuration.

2.3 Basic research on fiber array end face polishing

When the optical fibers are docked, due to the presence of end-face gaps at the butt joints of the two optical fibers or the presence of a high-refractive-index metamorphic layer on the optical fiber end-faces, these will also bring losses to the optical fiber devices due to the influence of materials.

In order to eliminate the longitudinal error of the end faces of the two optical fibers, the ferrule body of the optical fiber is generally made into a spherical surface. As long as the sag of the optical fiber on the end face of the ferrule body is less than 0.05um, the two optical fibers can be brought into physical contact when the connector is butted, and the connection can be made. The use of the device is very reliable.

Therefore, in order to improve the return loss of the fiber optic connector, it is necessary to remove the metamorphic material that has an error on the optical coupling produced by the diamond sandpaper during the grinding of the fiber end face. The removal process cannot produce fiber depressions and pits, which increases the defect. At the same time, the polishing process itself is an effective treatment method in this process.

Polishing experimental conditions, using flannel polishing pad (nylon) and alumina polishing pad respectively, the end face of the optical fiber connector is ground and then the polishing process test is carried out.

The condition of using nylon cloth is to use polishing suspension. The polishing suspension is made of silica suspension (0.05u) and pure water. The grinding speed is all 30r/min. The optical fiber end face before polishing must be roughly ground, ground and finely ground, and ground with 9μ, 3μ, and 1μ diamond sandpaper respectively. The total grinding time is 120s. When grinding, it is necessary to add an appropriate amount of flowing pure water as a cleaning agent to soften. The release agent can firstly prevent the optical fiber from denting during the grinding process, and the heat generated during the grinding process can be carried away by the flowing water to avoid damage to the equipment and optical fiber components.

The polishing scheme is shown in Table 1. The experimental results show that the use of nylon cloth polishing, the removal of optical fiber material is relatively small, but it will cause the center point of the optical fiber to be recessed relative to the substrate or the end face of the pin, and the polishing processing time is prolonged, and the center of the optical fiber end face is recessed. It will increase accordingly. From the previous removal mechanism, it can be seen that the nylon cloth polishing process belongs to the removal of microcrystals. Therefore, the longer the polishing time, the greater the amount of fiber sag.

During the period from 0 to 180s, the sag of the fiber end face grows at a relatively high rate, but it does not always increase, and will gradually reach a steady state of material allowance removal after that. The processing quality of the fiber end face is relatively good, and the surface roughness can reach 0.04μ.

The polishing time should be controlled between 0 and 120s, and the polishing pressure should be minimized to reduce the amount of fiber sag. After testing, the quality of the end face of the optical fiber is also good when using silica particles to polish.

Thirdly due to the different characteristics of the materials of the silicon oxide and nylon cloth, they have different removal mechanisms for the optical fiber material and the substrate or the pin body material. The nylon cloth polishing process improves the contact pressure distribution between the fiber and the end face of the substrate pin body. Uniformity, the polishing results are consistent with the theory, so it is recommended to use nylon cloth as the polishing pad within a certain range. When polishing the fiber end face, it is recommended to use nylon cloth for polishing when the end face coupling requirements of the fiber optic device are relatively high. In mass production in general factories, it can be polished with a silicon oxide polishing pad. At present, with the continuous improvement of the system speed, the Pc-type grinding process has also been continuously improved. The recent APC (Advance Physical Contant) technology, from a structural point of view, most of the APCs are based on angle grinding and polishing, which can improve the return loss. while reducing the impact of insertion loss on the system.

The impact of the grinding and polishing process on the quality of the fiber end face is the most critical. Since the fiber end face is in use, under the thermal stress of the coupled high-energy laser, if the fiber end face has fine scratches or other defects, these defects will increase the transmission energy. The situation gradually increases and becomes prominent, and will gradually decrease the coupling efficiency, increase the loss, interrupt the transmission and even cause the system to be paralyzed. Therefore, the end face processing quality of the optical fiber must be improved.

Through the experimental research in this chapter, the factors affecting the end face quality of the optical fiber components are analyzed: the particle size of the abrasive paper, the grinding time and the grinding speed, etc., and the causes of the defects in the processing process are analyzed, and the methods to improve the defects and improve the yield are proposed. The method basically solves the problem of optical fiber array grinding, and establishes the best processing parameters. The experimental process and results have reference significance for improving the quality of fiber array end face processing, and have certain reference value in the production of fiber array.

The specific conclusions are as follows:
(1) When grinding optical fibers with diamond sandpaper with an average particle size of 9μ~1μ, there are various material removal modes, and their effects on grinding are different.
(2) The greater the grinding speed, the greater the removal amount in the same time, the greater the particle size of the grinding sandpaper, the greater the grinding removal amount, and the higher the grinding efficiency. Of course, the polishing efficiency of the fiber array is not completely consistent with that of the single-filament fiber. Only when the fibers of the same dimension achieve the same polishing speed on the polishing disc, can the polishing effect of the fiber array be synchronized.
(3) Use nylon cloth for polishing. The longer the polishing time, the greater the depression of the fiber array. Using silicon oxide polishing, the polishing quality is good, almost no depressions are generated, and the polishing time has little effect on the amount of depressions.

3. Summary

In this paper, the design and experiment of the V-groove assembly calibration error, heat dissipation characteristics and grinding process of the semiconductor laser-coupled fiber array are carried out. The experimental results are:

In the context of this topic selection, it is given that the fiber R used is 150μ and the pitch width of the coupled laser array is 160μ, so the shape of the fiber slot can be directly calculated; for heat dissipation, we give the heat dissipation description of the material, and finally determine the si- The si substrate is used as a crimping substrate. The processing parameters are also given on the optical fiber coupling end face, that is, the optical fiber must have a free end, otherwise the coupling heat will accumulate, and the length of the free end is 1.5mm; in the optimization of the grinding process, the design of the grinding fixture takes into account the grinding efficiency, breaking the traditional single The chip grinding and polishing process also adopts the reverse grinding method of woolen cloth which is slightly available in the world. The efficiency and quality of the grinding process are improved.