Optical Fiber Fusion Splicer

Your professional optical fiber fusion splicer factory and supplier in China!

Melontel, one of the leading Chinese communication equipment manufacturers, is here today. This article will cover definitions, applications, specifications, and benefits, among other things. Continue reading to learn more.

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optical fiber fusion splicer1

Melontel

Your Professional Optical Fiber Fusion Splicer Manufacturer

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Optical Fiber Fusion Splicer Data Sheet

optical fiber fusion splicer1

With the increase of optical fiber types and the innovation of optical fiber technology, various network scenarios appear in the urban optical network. In the construction of the urban backbone optical cable ring network, large-capacity and multi-core optical cables are required, and ribbon optical cables are often used in local network hops with large core capacity requirements. In such a development process, the quality requirements of optical fiber splicing are getting higher and higher. Now the main way to realize optical fiber splicing is to use optical fiber fusion splicer. The use of high-performance automatic optical fiber fusion splicer is the primary condition to improve the working efficiency of optical fiber splicing and the quality of optical fiber splicing.

What is fiber optic cable?

optical fiber fusion splicer1

Optical cable is the main transmission tool of various information networks in today’s information society.

It is a communication cable assembly that utilizes one or more optical fibers placed in a sheath as a transmission medium and can be used individually or in groups. Optical cables are mainly composed of optical fibers (glass filaments as thin as hair), plastic protective sleeves and plastic outer skins. There are no metals such as gold, silver, copper, etc. in the optical cables, and generally have no recycling value.

Optical cable is a certain number of optical fibers composed of cable cores in a certain way. Optical cables can be divided into layered optical cables, central bundled tubular optical cables, and skeleton optical cables according to the core structure characteristics. The basic structure of optical cable is generally composed of cable core, reinforcing steel wire, filler and sheath, etc. In addition, there are waterproof layer, buffer layer and other components as needed.

What are the optical cable fusion tools?

In North America, distribution boards are usually housed in sheet metal enclosures with circuit breakers arranged in two columns that may be operated from the front. Some panelboards include a door covering the breaker switch handles.

Still, all have a dead front, which means that the front of the enclosure prevents the circuit breaker operator from coming into contact with active electrical parts within.

When the lid is removed, and the cables are visible during distribution board servicing, various live parts on American panelboards are frequently exposed. The primary switch or circuit breaker is positioned in a service box in Canadian service entry panelboards.

1. Optical fiber fusion splicer.

The optical fiber fusion splicer uses a high-voltage arc to melt two optical fibers, and at the same time uses the principle of collimation to smoothly advance the two optical fibers into one, so as to realize the coupling of the optical fiber mode fields. Ordinary optical fiber fusion splicers generally refer to single-core optical fiber fusion splicers. In addition, there are ribbon optical fiber fusion splicers specially used for fusion splicing ribbon optical fibers, leather wire fusion splicers for splicing leather cables and jumpers, and fusion splicing guarantees. Polarized optical fiber protection fiber fusion splicer, etc.

2. Cutter.

There are two types of cutters, manual and electric. The former is simple to operate and has reliable performance. With the improvement of the operator’s level, the cutting efficiency and quality can be greatly improved, and the bare fiber is required to be shorter, but the cutter has higher requirements on the ambient temperature difference. The latter has high cutting quality and is suitable for operation in cold conditions in the field, but the operation is more complicated, the working speed is constant, and the bare fiber is required to be longer.

3. Other tools.

Optical cable dermatome, optical fiber peeling pliers, wire cutters, screwdrivers, heat shrinkable tubes, alcohol, absorbent cotton, etc.

What is the principle of optical fiber splicing?

optical fiber fusion splicer1

The optical fiber connection principle is blue, orange, green, brown, red, black, yellow, purple, pink, cyan according to the color spectrum. Multi-core optical cable is to put optical fibers of different colors in the same bundle tube, (for example, stranded optical cable) such an optical cable has several bundle tubes, which are opposite to the section of the optical cable, generally red is the filling rope, in order Green casing, white 1 tube, white 2 tube, white 3 tube, white n tube. When the number of connected cores is equal, the corresponding color fibers in the same bundle tube are butted, and when the number of cores is not equal, connect the larger number of cores first, and then connect the smaller number of cores.

 

How to splicing fiber optic cables?

splicing fiber optic cables

Before welding, prepare necessary operating tools and materials such as fiber strippers, cutters, optical fiber fusion splicers, etc., check whether the power supply is connected well, and check whether the machine is damaged. If working outdoors, check whether the battery power is sufficient, and pay attention to the surrounding Whether the environment (temperature, pressure, etc.) allows and shuts down the fiber fusion splicing work, if the conditions do not allow it, stop the work, and wait until the conditions are mature before proceeding, so as to avoid damage to the fiber optic fusion splicing equipment and cause unnecessary losses.

Before the optical cable is spliced, the necessary equipment should be prepared first, and the work surface should be arranged to avoid accidentally breaking or hanging the optical fiber during splicing, especially in the field.

Strip the cable

Use an optical cable dermatome to peel off the outer sheath of the optical cable, the length of which is 1.2 meters to 2 meters. At the same time, fix the end of the optical cable and the reinforcing steel wire. The reinforcing steel wire and the end must be tightened and not loose.

When fixing multi-bundle tube-layer optical cables, due to the layered fiber, the bundles are placed in order to distinguish them. Be careful not to damage the bundles.

Peel off the bundle tube, wipe the grease off with toilet paper, and cover the fiber to be fused with heat shrink tubing.

Preparation of Fiber Sections

CPreparation of Fiber Sections

Communication fiber consists of three parts: core, cladding and coating. The core diameter of base mode fiber is only 4~10um, and the cladding diameter is 125um. If the fiber end face is not treated, the fiber end face will be rough and uneven. The end face treatment will be directly welded, and the splicing loss will be greatly increased. Therefore, the end face treatment before the optical fiber welding is an indispensable step, and the specific content includes the three links of stripping, cleaning and cutting.

(1) Stripping of the optical fiber coating. The optical fiber coating is generally stripped by 30mm-50mm. Different fiber networks, different parts, and different functions will lead to different processes for preparing bare fibers. The usual operations are:

The first is to loosen the tight cladding and the loose tube, strip off the optical fiber protection bundle, and wipe off the ointment that fills the optical fiber.

The second is to “determine the node of the fiber and the direction of the fiber” to ensure that the length of the remaining fiber of the fiber meets the design requirements.

The third is to repeatedly wipe the bare fiber with anhydrous alcohol, and pay attention to maintaining the unity of the direction. Finally, use Miller clamps to strip the fiber coating; you can also use a thermal stripper to pull out the bare fiber after heating the fiber coating.

Cleaning of bare fibers

Tear the cotton soaked with alcohol into small fan-shaped pieces with a flat surface, fold it into a “V” shape, clamp the fiber to be stripped, and wipe the fiber along the axis of the fiber. For replacement, different parts and layers of cotton are used each time, so that the utilization rate of cotton can be improved, and the double pollution of fiber detection can be prevented.

Absolute alcohol should be used when cleaning the optical fiber, which can avoid the absorption of 19pm, 1124pm and 1139pm in the OH pair of optical fibers. In addition, ultrasonic cleaners can be used to clean the optical fibers in areas where conditions permit. This processing speed is fast and the quality is good. “It is not easy to cause accidents to occur.

Cutting of bare fibers

The cutting of bare fiber is the most critical part in the preparation of the fiber end face. In this step, a precise and excellent cutter is the foundation, and strict and scientific operation specifications are the guarantee.

The operator should select the appropriate bare fiber length (usually 15mm) according to the cutting operation specification. The cutter should be placed smoothly, and at the same time, the cross-section should be prevented from contamination. The heat shrinkable tube must be inserted before the fiber is stripped. penetrate.

The premise of fiber splicing is that the fiber end face should have no defects, no burrs, the angle should be as small as possible, and the end face should be as flat as possible. If there is dislocation, tilt, or port contamination, it will directly lead to an increase in fiber splicing loss.

At this time, it is required that the end face of the fiber after cutting is flat, free of burrs, no defects, and the cutting angle is as small as possible. Displacement of the axis, tilting of the axis and dirt on the end face will all lead to an increase in the welding loss.

The main methods of cutting optical fibers are mechanical cutting and ultrasonic electric cutting. The mechanical cutting knife is a cutting method in which the optical fiber is fixed in the positioning groove by pushing the blade to cut the optical fiber. There is also a mechanical cutting method by pressing down on the cutting platen. cut the fiber;

The working quality of the ultrasonic electric cleaver is higher than that of the mechanical type. The motor is used to tighten the optical fiber pressing block to tighten the optical fiber, and then the optical fiber is gently touched by the ultrasonic wave with the knife surface to cut the optical fiber, which has the advantages of precision and smooth port.

Fiber splicing

Fiber splicing

Turn on the power of the fusion splicer and select the appropriate fusion splicing method. Put the fiber in the V-shaped groove of the fusion splicer, carefully press the fiber clamp and the fiber clamp, set the position of the fiber in the clamp according to the fiber cutting length, and put it into the draft shield correctly.

During the welding process, the “V” groove, electrodes, objective lens, welding chamber, etc. of the optical fiber fusion splicer should also be cleaned in time. The welding loss given by the optical fiber fusion splicer is generally below 0.03DB. The operator needs to observe whether there are bubbles in the welding at any time, If there are bad phenomena such as too thin, too thick, virtual melting, separation, etc., pay attention to the tracking and monitoring results of the OTDR, analyze the reasons for the above-mentioned bad phenomena in time, and take corresponding improvement measures.

coil fiber

Coiled fiber is a technology and an art. The scientific method of coiling fiber can make the fiber layout reasonable, the additional loss is small, can withstand the test of time and harsh environment, and can avoid fiber breakage caused by extrusion.

Before splicing, the length of the optical fiber can be measured in the optical fiber receiving tray of the splice box in advance, so that the optical fiber can be neatly arranged. According to the length of the remaining fiber and the size of the reserved space, coil it naturally according to the situation, and do not pull it hard. You should flexibly use circle, ellipse, “CC”, “~” various shapes of coil fiber (note that R≥4cm), as far as possible Make use of the reserved space and effectively reduce the additional loss caused by the coiled fiber.

Splice point protection

Splice point protection

The key after fiber splicing is to protect the splicing point in time, which helps to ensure the quality of fiber splicing.

There are two general protection methods for optical fiber fusion splices: heat shrinkable tube protection method and coating protection method. The heat shrinkable tube protection method is to take out the optical fiber and move the optical fiber after the optical fiber is spliced ​​so that the fusion point is in the middle of the heat shrinkable tube, and put them together in the heater integrated on the fusion splicer to heat shrink.

Because the heat shrinkable tube has a steel rod that cannot be bent, it can protect the welding point.

The coating protection method is to use a coating machine to coat the bare fibers near the fusion point with silicone resin or other materials. After coating, the outer diameter of the bare fiber can be basically the same as the original fiber, and the tensile strength is up to 20N, and the bending radius is basically unchanged.

This method is complicated to operate and requires specialized equipment only for special occasions.

How does mechanical fusion work?

Heating of the end face

Fiber splicing generally uses gas discharge to heat the fiber end face by arc. Therefore, before fiber splicing, ensure that the fiber end face is clean. The pre-discharge method of the fiber end face can be implemented to remove sundries and dust from the optical port. “And ensure the smoothness and angle of the fiber port”, and on the basis of keeping the pressure of the fiber port uniform, “ensure the quality of fusion splicing.” .

mechanical fusion work

Fiber Alignment

Optical fiber alignment determines the quality of optical fiber fusion. The standard practice is to clamp the fiber with the processed end face on the left and right fiber pressure plates of the fusion splicer, and operate the fusion splicer to align the fiber cores.

The fusion splicer automatically aligns the fiber core and relies on its control system to control its dense motor system to ensure fast and accurate fiber alignment.

The control systems used by the current fusion splicers are based on three most important technologies: side image projection alignment system PAS, fiber core detection system CDS and local light injection and detection system LID, which should be targeted according to the type and requirements of the fusion fiber Choose the world’s best control system.

To achieve firm, low-loss fusion splicing of optical fibers in the fusion splicing process, the alignment method before optical fiber fusion splicing is the key, and it is also one of the technical bottlenecks for low-loss fusion splicing of optical fibers. At present, the optical fiber alignment methods mainly include the following: (fiber core image alignment system, and lens imaging profile alignment system improved in its technology; (high-definition imaging alignment system; (thermal imaging fusion control; (optical power) detection system.

Workers are operating optical fiber fusion splicer

Fiber splicing

Before splicing optical fibers, the corresponding fusion splicing procedure should be selected according to different types of optical fibers (such as single-mode optical fibers, multi-mode optical fibers, and dispersion-shifted optical fibers, etc.).

The fusion splicing of the optical fiber is the same as the heating method of cleaning the end face. The gas discharge generates a high temperature arc to melt the end faces of the two optical fibers. At the same time, the motor system pushes the two optical fibers toward each other to realize the fusion.

After the welding is completed, if there are abnormal phenomena such as bubbles, thin diameters, and dislocation of the core at the welding point, it needs to be welded again.

What are the main factors affecting the splice loss of optical cable?

The influencing factors of fiber splice loss can be divided into intrinsic factors and extrinsic factors.

Fiber splicing

Intrinsic factors refer to some factors of the fiber itself, such as the inconsistency of the mode field diameters of the two fibers, the mismatch of the fiber core diameters, the non-circular core section, and the poor concentricity between the core and the cladding. Extrinsic factors refer to the influence of various human factors, instruments and other factors on the splice loss.

The G652 standard of the International Telegraph and Telephone Consultative Committee (CCITT) stipulates that the nominal value of the mode field diameter of the 1310nm window is within 9~10pm, and the deviation shall not exceed 10% of the nominal value. Within this tolerance range, after an optical fiber with a mode field diameter of 11 μm and another optical fiber with a mode field diameter of 9 μm are spliced ​​under very good splicing conditions, the theoretical calculation value of the splice loss at the joint can reach 0.17dB. The actual continuation is higher.

1. The fiber mode field diameter is inconsistent. The size of the mode field diameter is related to the wavelength used. As the wavelength increases, the mode field diameter also increases.

2. The core diameters of the two optical fibers are mismatched;

3. The concentricity between the core and the cladding is not good;

4. The core section is not round.

Among the intrinsic factors, the factor that has the greatest impact on the fiber splicing loss is the inconsistency of the fiber mode field diameter. According to the CCITT recommended standards, the tolerance standards of single-mode fiber are as follows: The mode field diameter is (9~10um) ±10%, that is, the tolerance is about ±1um, and the diameter of the cladding is 125±3um;

Mode field concentricity error ≤6%, cladding out-of-roundness ≤2%.

extrinsic factors

Extrinsic factors refer to the influence of various human factors and equipment and other factors on the splice loss, such as the misalignment of the optical fibers during fusion, and the theoretical value of the fusion loss when the axes of the two optical fiber cores are radially offset by 2pm. Can reach 0.74dB;

The theoretical value of the splice loss can reach 0.46dB when the two optical fibers are tilted axially and the tilt angle reaches 1 degree;

When the sum of the inclination angle of fiber end face cutting reaches 1 degree, the theoretical value of fiber fusion is 0.21dB;

The operation level of the splicer also affects the splicing loss. According to some data, the same equipment is operated by different people, and the total loss difference of 10 splicing points can reach up to 0.32dB;

The fusion splicing loss caused by the optical fiber splicing technology is the extrinsic factor of the optical fiber splice loss. The main extrinsic factors are as follows:

1. The optical fiber axis is tilted: this loss occurs during the processing of the fiber end face. If the fiber end face is still tilted by 1° after processing, it will produce a splicing loss of about 100. If you want to control the splicing loss value within the range of ≤ 0.1dB In this case, the inclination angle of the single-mode fiber end face treatment should be controlled within 0.3°. It can be seen that the fiber end face treatment is an important factor affecting the optical fiber fusion splicing error.

2. Dislocation of the fiber axis: Since the core of the single-mode fiber is relatively small (usually 4~10um), the dislocation of the butt fiber axis directly affects the connection loss.

For example, when the axes of the two butt-jointed optical fibers are misaligned by 1.2um, the splice loss can reach 0.5dB, so the misalignment of the axes should be avoided as much as possible.

3. Physical deformation of the optical fiber near the splice point: the tensile deformation of the optical cable during the erection process, the pressure of clamping the optical cable in the splice box, etc., will also affect the splice loss, and even several times of welding can not be improved.

4. End-face separation: When the connection of the movable connector is not good and the discharge voltage of the optical fiber fusion splicer is low, the end-face separation is easy to occur, resulting in a large connection loss.

5. End face quality: In the previous introduction to the fiber end face preparation process, it has been mentioned that the end face quality should be improved. It can be seen that bad end faces such as broken fibers, bevels, and burrs will increase the connection loss of the fiber.

6. The operation level of the splicer: There is information that the same equipment is operated by different people, and the total loss difference of 10 welding points can reach up to 0.32dB, so it is necessary to train the operator before the splicing.

In addition, the coiling of optical fibers in the splice package, the coiling of reserved optical cables, the splicing parameter settings of the fusion splicer, the cleanliness of the discharge electrodes, and the cleanliness of the splicing working environment all have different degrees of influence on the optical fiber splicing loss.

How to test the loss of optical fiber fusion?

The measurement methods of the fusion loss of optical fiber connectors mainly include the direct-view local monitoring method of the mandrel, the shearing method and the optical time domain reflectometer measurement method. We will briefly introduce the shearing method and the local monitoring method of the direct-viewing mandrel, and then focus on the optical time Domain reflectometer and perform a simple comparative analysis.

Full set of optical fiber fusion splicer

Mandrel direct view local monitoring method

Some optical fiber fusion splicers come with a system for measuring the fiber splicing loss based on the principle of direct view of the optical fiber core. The image is processed and analyzed to determine the offset of the cladding, the distortion of the core, the change of the outer diameter of the fiber, and other key parameters. Finally, these parameters are substituted into the set program to calculate the loss value of the fusion splice.

It is worth noting that this method calculates the loss value based on the image of the welding. The advantage of this method is that the measurement is fast and timely, but its measured value is likely to be quite different from the real splice loss value, so this The measurement does not accurately represent the true value of the welding loss, and is generally used for reference only.

shear method

The shearing method is a method with the best measurement accuracy. Its measurement principle is very simple. First, connect the optical power meter at the output end to measure the output optical power, then cut the fiber at the input end, connect the optical power meter, and measure The output optical power is , and finally the fiber loss is directly calculated as: . However, a major disadvantage of this method is to cut the optical fiber, which is destructive to the optical fiber, which is not conducive to practical application.

Selection of Fiber Splice Loss Evaluation Methods

Signal fire AI-9 Fiber fusion splicer

The evaluation of optical fiber splice loss usually has two methods: splice loss estimation method and online splice loss measurement.

The splice loss estimation method uses the image to analyze the fiber core deviation. The specific parameters include the core deviation, the core warpage and other parameters. The fiber splice loss is calculated by an empirical formula.

This technology cannot cover all the mechanism of splice loss, it only uses a few parameters to estimate splice loss, so this method is called splice loss estimation method.

This method usually leads to an over-optimized estimation of the splice loss when the wrong parameters are used or the actual loss is relatively high.

Local optical injection and detection technology enables bidirectional or unidirectional in-line splice loss measurement.

Time-division light is injected into the optical fiber from the front end of the connector, and then detected from the back end of the connector;

It is injected into the fiber from the rear end of the splice and then detected from the front end of the splice.

Usually bend couplers are used to provide easy fiber insertion and removal, with a special design to optimize stress on the fiber and protect the fiber from damage.

The splice loss can be defined by the detected external optical power. The loss value measured online is closer to the loss value measured by the OTDR. It is superior to the splice loss estimation method. This also ensures the accuracy of optical fiber splice loss measurement.

Selection of Fiber Core Alignment Methods

optical fiber fusion splicer1

The traditional fusion splicer splicing is to use the direct view method of the fiber core.

It adjusts the dislocation of the X-axis and Y-axis of the optical fiber, and splices when the dislocation of the axis is the smallest. During the entire adjustment of the axis and the fusion splicing process, the information of the detected state of the spliced ​​fiber core is sent to the fusion splicer through the camera. In the dedicated program of , the loss value after the connection can be calculated.

It can only indicate the degree of alignment of the fiber axis, and does not include the loss affected by the inherent characteristics of the fiber itself, and the indirect alignment method through indirect calculation, so the estimation error of the loss is large, and it is difficult to know the exact value of the joint loss on site. of.

This method of adjusting the axis requires a complex and precise optical system, so the welding time is long.

The direct alignment of the local optical injection system, in order to ensure the true and accurate core-to-core fiber alignment, the optical fiber needs to move and adjust the position in the X-axis and Y-axis directions, so that the local injected optical power detects the maximum transmission power locally. This approach ensures the most precise core-to-core fiber alignment.

The method is simple and effective, and it does not require complex and precise optical systems and any form of environmental sensors, so it is more reasonable to use a local optical injection system to directly achieve fiber core alignment.

How to improve the working efficiency of optical fiber fusion splicer?

optical fiber fusion splicer1

Fiber Type Automatic Identification

Before fiber splicing, a mode field diameter measurement is performed to determine the single-mode fiber type.

The mode field diameter of different single-mode fibers such as dispersion-shifted fiber and standard single-mode fiber can be detected by the lateral migration method, and then the fiber type can be determined by comparing with the memory data.

When the transmission power is measured by the local injection detection system, one end of the fiber is laterally offset, and the lateral offset of the fiber varies. If the distance between the fiber end faces is small enough, the field strength is approximately a Gaussian distribution.

The near-field scanning method is used to measure, and according to the definition of the mode field diameter of the single-mode fiber, the width corresponding to the maximum value 1/e of the field intensity distribution curve in the fiber core is read out, and its value is the mode field diameter 2ω0.

This method is commonly used to measure the spot size, to determine the mode field diameter, and to detect and identify dispersion-shifted fibers and standard single-mode fiber types.

For multimode fibers, if the above-mentioned method is used to measure the mode field diameter, the result is usually erroneously obtained values ranging from 16μm to 30μm.

For multimode fibers of different sizes, use the lateral offset method to increase the lateral offset to identify.

The mode field diameter of erbium-doped fiber is about half of that of conventional single-mode fiber, so it can also be identified by the lateral shift method.

By automatically identifying the fiber type and selecting the appropriate fusion splicing program, it can minimize the influence of the user on the selection error and improve the compatibility of the fiber fusion splicer.

L-PASTM Profile Projection Alignment System

The side image projection alignment system is to collect image data by two sets of cameras set on the X and Y axis two optical paths at the same time to evaluate the image of the fiber end face, use the contour contrast of the fiber end face to control the fiber alignment, and digitally provide the image. Analysis, get information on fiber position, end face condition and contamination condition, including image of fiber center, possible damage, fiber offset and tiny contamination, and then can automatically compensate for poor fiber cut surface.

The current compatible fiber cleave angle is up to 2.5°.

Since the requirements for the end face of the optical fiber fusion splicer are reduced, the rework rate of optical fiber preparation is greatly reduced, the work efficiency is improved, and the service life of the end face production tool is prolonged.

Loss evaluation of fusion splicers

There are two ways to evaluate the loss of fusion splicer: one is to use the image to analyze the deviation of the fiber core, thereby defining specific parameters (such as the fiber end face angle, the deviation of the core, the warpage of the core, etc.).

The splice evaluation loss is calculated by the empirical formula using the above parameters.

Another control system using LID technology evaluates the splice loss closer to the real value, but because the optical properties of the optical signal such as reflection, absorption, and scattering at the interface of the fiber to be fused at both ends are the same, the evaluation loss value and the actual loss are also different. There will be deviations.

Adaptation of Optical Time Domain Reflectometry (OTDR)

Optical Time Domain Reflectometry (OTDR)

When the difference between the main line evaluation loss and the OTDR test loss is too large, it should be noted that the test technology principles of the two are different.

It must be used in the construction and acceptance of optical cables. Only TDR can measure fiber splice loss.

The working principle of 0TDR is: by sending optical pulses to the fiber, at the same time receiving the Fresnel reflected light and Rayleigh backscattered light at the input end, converting the received optical signal into an electrical signal and processing the signal to obtain the fiber length. , loss and other fiber parameters. Use OTDR to test the splice point loss and re-splicing should be done in time once it exceeds the standard.

Selection of Fiber Splice Loss Evaluation Methods

The evaluation of optical fiber splice loss usually has two methods: splice loss estimation method and online splice loss measurement.

The splice loss estimation method uses the image to analyze the fiber core deviation. The specific parameters include the core deviation, the core warpage and other parameters. The fiber splice loss is calculated by an empirical formula.

This technology cannot cover all the mechanism of splice loss, it only uses a few parameters to estimate splice loss, so this method is called splice loss estimation method.

This method usually leads to an over-optimized estimation of the splice loss when the wrong parameters are used or the actual loss is relatively high.

Local optical injection and detection technology enables bidirectional or unidirectional in-line splice loss measurement.

Time-division light is injected into the optical fiber from the front end of the connector, and then detected from the back end of the connector;

It is injected into the fiber from the rear end of the splice and then detected from the front end of the splice.

Usually bend couplers are used to provide easy fiber insertion and removal, with a special design to optimize stress on the fiber and protect the fiber from damage.

The splice loss can be defined by the detected external optical power. The loss value measured online is closer to the loss value measured by the OTDR. It is superior to the splice loss estimation method. This also ensures the accuracy of optical fiber splice loss measurement.

Read more about Fiber Optic Connector

Improve the stability of optical fiber fusion splicer by adopting a new type of electrode

optical fiber fusion splicer1

The stability of the optical fiber fusion splicer is that under normal working conditions, the optical fiber fusion splicer can achieve a relatively low splicing loss without maintaining it for a long time, and the average loss remains relatively stable.

Most of the conventional optical fiber fusion splicers use the arc generated by the discharge between the electrodes to heat the optical fiber for fusion splicing.

The key to achieving stable splicing performance is stable fiber heating during the splicing process. However, with the increase of the number of splices in use, contaminants will be deposited on the end of the electrode. These contaminants are caused by the high temperature during the splicing process that evaporates the silica on the surface of the optical fiber, and a part of the evaporated silica is deposited on the top of the electrode and follows with As the number of discharges increases, a layer of deposits is formed.

The deposited silicon dioxide acts as an insulator to form randomly distributed regions of low conductivity on the electrode surface. The electrode will remain in the high-conductivity area to discharge, because the high-conductivity area is in a state of random intervals, a small change in the electrode discharge conditions will lead to a more suitable location for the arc to occur.

The result is a natural variation in the electrode discharge location.

This will cause the heating of the fiber to become unstable over time, with the result that the quality of the splices will deteriorate significantly.

To obtain consistently low splice wear, regular maintenance of the electrodes is necessary. But maintaining electrodes is a time-consuming task, which can significantly reduce the efficiency of the fusion splicer. Since the cleaning process of the electrodes is done manually, the cleaning quality is largely dependent on the operator.

Although there are different types of cleaning tools available, it still means that the operator of the fusion splicer needs to be trained in electrode removal, installation, and cleaning. But even the best training can’t avoid mistakes that can occur during operation, such as insufficient cleaning, damage or contamination of the electrode tip due to mishandling, or incorrect electrode installation after cleaning. All of this can lead to splicing results that are even worse than before cleaning.

The new electrodes with arc stabilizers hold the arc in place by means of something far less sensitive to contamination on the electrode surface.

As the arc discharge position is forced to be fixed, the fiber heating becomes stable accordingly, and finally a small splicing loss can be continuously obtained.

Unlike electrodes that require mechanical cleaning, the new electrodes with arc stabilizer are maintenance-free. The fusion splicer ensures consistently low splicing losses over more than 5,000 splicing operations by automatically applying the clean arc, with a 50% reduction in average loss and standard deviation compared to standard electrodes. This electrode makes the stability of the performance of the fusion splicer better guaranteed.

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The development history of optical fiber fusion technology

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The research on the optical fiber fusion method was first started in 1971 by Bis Bee of the Bell Research Institute in the United States.

He used nickel-chromium wire as a heat source to melt the multi-component optical fiber with a low point (below 1000 degrees Celsius, and the connection loss reached 0.48dB. However, for the silica fiber with better transmission characteristics and reliability, its melting point Higher (about 1800 degrees Celsius), it cannot be welded by this method.

Toyama and Shiya of Japanese companies and Kohanazad eh of Corning Corporation of the United States have successively adopted the method of air discharge in the fusion splicing of silica optical fibers, using arcs to melt two optical fibers and connect them together. The average connection loss of the fiber is .

Fujita et al. of Hitachi, Ltd. proposed a method using a carbon dioxide laser. In this way, the connection loss of the abrupt optical fiber is all below, but this device requires large volume and high price, which is not conducive to practical application.

R. Jocteur et al. proposed a flame heating connection method, in which there are two alternative heat sources, namely a micro-ion torch and an oxygen-oxygen micro-flame lamp.

Using the oxygen-oxygen microflame lamp to weld the mutant fiber, the average loss is 0.16dB.

Using a micro-ion torch, the average loss of the abrupt fiber is 0.10 dB for the graded fiber.

High-strength joints can be obtained for flame heating pavilions, but they cannot be used on site because the equipment is very complex, the environment is required to be clean, and the control is more troublesome.

Hirai et al. of NTT Company in Japan proposed a new method with low loss and stable connection, called “preheating and wiping method”, that is, preheating and shaping the fiber end face by discharge heat, and then in the case of discharge, Move one fiber in the axial direction and finally melt the two polar fibers together. Now almost all of the fiber optic splicing machines produced around the world use this preheating fusion splicing method.

After years of development, the main features of the optical fiber flame splicing machine are: the multi-mode optical fiber fusion splicing technology is relatively mature, and the single-mode optical fiber fusion splicing technology has been practical;

The volume of the welding device is gradually reduced, and the degree of automation is gradually increased; the machine has stronger adaptability to the environment, the operation time of welding is getting shorter and shorter, and the performance of the optical fiber fusion splicer is more and more stable.

How to reduce the splice loss of fiber optic connectors?

Use the same batch of high-quality brand-name bare fibers

As mentioned above, the fiber mode field diameter in the intrinsic factor of the fiber will have a great influence on the fusion splicing loss. For the same batch of fibers, the mode field diameter is basically the same. After the fiber is disconnected at a certain point, the difference between the two ends The mode field diameters can be considered consistent.

Therefore, the fusion splicing at this breaking point can minimize the influence of the mode field diameter on the fiber splicing loss, thereby avoiding the large fusion splicing loss of the optical fiber joint due to inconsistent fiber mode field diameters.

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Basic requirements for fiber optic cable erection

When laying the optical cable, the mechanical traction method of stepless speed regulation must be adopted. The optical cable must be released from the top of the system and kept in a loose arc without twisting. Do not bend and twist in small circles, so as to minimize the damage to the optical fiber in the optical cable. probability.

Select experienced and well-trained fiber optic splicing personnel for splicing

Although most of the optical fiber fusion splices are automatic fusion splices, the level of splicing personnel will directly affect the size of the splicing loss.

Therefore, it is required that the splicing personnel should conduct the splicing in strict accordance with the optical fiber fusion splicing process, and the splicing loss of the fusion splicing point should be tested in real time during the fusion splicing process. Repeated flame pick up 3 to 4 times.

The splicing of optical cables should be carried out in a clean environment

The splicing of optical fibers must be carried out in a clean environment. It is strictly forbidden to operate in the open air in a dusty and humid environment. This will not only cause a large loss of fusion splicing, but also cause damage to the fusion splicer. Keep it clean, the fiber optic connector must not get wet, and the optical fiber must also be clean, and there must be no dirt on it.

Correct use of optical fiber fusion splicer

It is necessary to correctly and reasonably set the welding parameters, pre-discharge current, time, main discharge current, main discharge time, etc. according to the type of optical fiber. The dust in the optical fiber fusion splicer should be removed in time during and after use, and the optical fiber fusion splicer should be placed in the optical fiber fusion splicer before each use. If it is placed in the environment for at least 15 minutes, the service life of the electrode of the optical fiber fusion splicer is generally about 2000 times, so the cleaning program must be run to clean the electrode after every 20 times of discharge welding.

Optical system of optical fiber fusion splicer

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Since the fiber core and cladding have different refractive indices, the spatial distribution of parallel light entering the fiber from the side after passing through the fiber will change (ie, the energy distribution will change), and this distribution varies with the position of the fiber. changes with the change.

Therefore, we can detect the energy distribution of the outgoing light to determine the exact position of the fiber core. The current effective detection method is to use an accurate imaging lens to image the energy distribution of the light on the CCD receiver.

When the X light source is bright, the light is irradiated on the optical fiber through the mirror, and the light passing through the optical fiber is amplified by the optical system and sent to the CCD sensor, and then the electrical signal of the light is sent to the image processing system. are the X and Z positions of the fiber. Similarly, when the Y light source is bright, the X- and Z-direction positions of the optical fiber are obtained by measuring the CCD.

It is worth noting that after the X and Y light sources are reflected by the mirror, they are irradiated on the optical fiber perpendicular to each other.

Therefore, when the single-chip microcomputer controls the X light source and the Y light source respectively, the XYZ three-dimensional signal can be output from the CCD area scan camera. After the signal is processed by the image, the axial deviation, axial inclination angle and end face position of the optical fiber are sent to the film machine. , the single-chip microcomputer then controls the motor telescopic micro-displacer to move the V-shaped groove to realize three-dimensional precise micro-adjustment, achieve precise automatic alignment, and then control the discharge of the high-voltage welding circuit, and at the same time push the optical fiber in the optical fiber axis to connect the optical fiber.

Summarize

Optical fiber cable fusion is a meticulous work, especially in end face preparation, fusion, fiber coil and other links. In the daily welding work, it is necessary to be good at summarizing and develop good recording habits for future maintenance. In short, this is a job that requires the operator to observe carefully and consider carefully.