The development of Optic Fiber Arc Fusion Splicing

The use of communicating via light undoubtedly goes back many centuries. The Chinese and Native Americans were the first to use smoke signals for long distance communications, a type of Optical Communication Link. The idea of sending light signals over a medium (today silica glass fiber), was first demonstrated in 1841 when Jean-Daniel Colladon of London revealed Total Internal Reflection (TIR) using sunlight and water streams. Other nineteenth century inventors that studied TIR includes John Tyndall, William Wheeling and Alexander Graham Bell.

In 1880 Alexander Graham Bell developed the Photophone, a system that used sunlight to send light signals up to 200m via strategically placed mirrors to a light-sensitive selenium resistor which was wired to a battery and telephone receiver.

It is abundantly clear that humans had the inspiration to develop the technology to transmit information using light. I am sure in the early days of fiber communication, distance was important and voice communications were the number one consideration. Today, of course, speed plays a pivotal role and fiber is used for voice and Terabytes of data information, which include audio, broadband internet, video on demand, live streaming services and many more. One strand of fiber is comparable to 1000 pairs of copper cable and can carry 32000 conversations.

Our modern world would have been a very different place without fiber networks covering the globe. Fiber brings these services straight to our businesses and homes (FTTx). Other significant uses for fiber were developed and fiber optics are also used in sensors and sensory systems, in power engineering, mechanical engineering, chemical, petrochemical, mining, automotive industries, health care and various other applications.

Optoelectronics is the field of engineering which includes Optical Transmission which is accomplished by using an Optical Laser to send digital light frequencies over Optical Fiber Networks. The light source is captured by an Optical Receiver. The fiber is typically silica glass which is drawn into a diameter roughly the size of a human hair. The fiber consists of a core, the part that carries the light transmission and is surrounded by a transparent cladding. The cladding has a lower index of refraction and the light travelling through the core reflects off the cladding.

 

 

Three types of fiber exist; however, the third type is still in final development. These are Single Mode (SM) fiber, Multimode fiber (MM) and Few Mode Multicore Fiber (FM-MCF). SM fiber is the most common type for long distance communication links. MM is suitable for short distance and data communications links. FM-MCF fiber will have up to 12 cores in a single strand of fiber and will be able to transmit several frequencies, i.e. multiple modes at once. This will save space and greatly enhance transmission speed. FM-FCF fiber is currently being developed by Fujikura and NICT (National Institute of Information and Communications Technology Japan) as a joint venture. Fujikura has also developed Theta-alignment splice machines capable of splicing the 12 cores spot-on.

Fujikura Ltd, a Japanese company, was founded in February 1885 by Zenpachi Fujikura. The company started by manufacturing silk and cotton insulated winding wires. After experiencing electricity for the first time in 1883, Zenpachi decided to use his knowledge of the hair braiding industry (his first business) to start Fujikura Electrical Company. The first silk-/cotton-insulated winding wire plant started operation at 1-1, Awaji-cho, Kanda, Japan in February 1885 with a staff of 12 people. Since then Fujikura has grown to an industrial giant with over 50 000 employees and clocking over USD6 Billion per annum. Fujikura has become one of the largest cable manufacturers in the world, specializing in many industries including electrical and telecommunications cable, optic fiber cable, automotive products, flexible PC boards, energy, electronics, golf accessories, real estate and most importantly fiber optic equipment, including specialist arc fusion splice machines since 1978 and the development of the world’s first Core-alignment Optical Arc Fusion Splicer in 1985.

Optical fiber was successfully developed in 1970 by Corning Glass Works. With the advent of optical fiber cables, one of the challenges that presented itself was the joining of two fibers. In the beginning it was much easier as the available fiber was Multimode which features a larger core. The first technology available was mechanical splices, which used a connecting jelly in a casing to join the fibers. This method worked well; however, the losses over these types were quite large and not suitable for long distance transmissions as mechanical connectors are also temperamental and environmental factors influences the longevity of the quality of the splice.

A new method had to be found to splice the fibers in a way that minimized the transmission loss (measured in decibels or dB’s) and to be more permanent and stable. The challenge was to line up two fibers that are the width of a human hair. No such technology existed; however, in 1978 Fujikura developed the first Splice Machine, Fujikura FR-1. The unit was comprised out of an electro-mechanical component and a microscope. The alignment was done manually by the fiber technician, using the microscope to see the fibers and manually aligning using X- and Y-axis adjustment screws. If the technician did everything correctly, the splice would be successful. If not, he would have to start again. Each splice could take up to approximately 30 minutes (depending on the operator) and it was very difficult to produce a good splice. (A good splice would typically have a loss of less than 0.02db).

By 1980 Single Mode fibers were developed and in 1985 Fujikura launched the world’s first fully automated Arc Fusion Splicing Machine, the F-20. This was the first splicer to use the PAS system now common in all modern splicing machines. In 1987 the unit was upgraded to the FSM-20C and in 1990 the FSM-20CS came to light. “FSM-20” was recognized worldwide as having excellence and was put into mass production. The FSM-20 moved Fujikura into the no. 1 world market position and today, almost 4 decades later, Fujikura still remains the world market leader in splice equipment with its share exceeding 50%. Since then Fujikura has launched a new model every 4 to 5 years. Each model is more advanced, more accurate and faster than the previous model.

In March 2015, Fujikura received the GLOBAL FUSION SPLICERS CUSTOMER VALUE LEADERSHIP AWARD from Frost & Sullivan, Inc. This award recognizes the high quality and reliability of Fujikura optical fiber fusion splicer. In addition, it gives recognition to the price competitiveness and good after-sales service provided by Fujikura’s worldwide distribution network which are highly valued by customers.

Profile Alignment System or PAS is the intelligent recognition of the core of the fiber. The splicer detects the refraction of light caused at the core-cladding interface. Images are taken in two orthogonal planes so that the core can be located precisely. The unit uses high precision stepping motors to align the fiber. It is aligned on the X-axis and Y-axis. The camera focus point on the fiber is also adjusted. A modern core-alignment splice machine uses 6 stepping motors to align the fibers. The splicer will also use the PAS information to determine the type of fiber, i.e. MM, SM, DS, NZ or BIF. The splicer reads the cleave angle of the edges of the fiber and checks for foreign anomalies like dust or moisture. In a modern Fujikura splicer, all of this is done in seconds.

Once the fiber-type, checks and alignment are completed the splicer typically does a cleaning arc to remove any dust or lint debris from the fibers. The next step is the splice arc. The splicer arcs at 8000 Volt DC across two electrodes. The arc is carefully controlled by a very sophisticated algorithm which sets the arc frequency, arc power and duration. The stepping motors move the fiber in whilst the unit arcs and a perfect connection is achieved.

The splicer reads environmental factors, i.e. temperature, humidity and altitude before and during the splice arc and automatically adjusts the algorithm to the environment. It uses this information as well as the splice loss measured across the splice to adjust the algorithm for the next splice. This keeps the splicer accurate even if environmental changes occur. Manual arc calibration is also possible and recommended especially if major environmental changes occurred since the unit was last used.

When the splice process is done, a tensile strength test is done by pulling on the fiber to ensure it does not break and automated checks for any anomalies like bubbles, bulges, lines, shadows, etc. are done.  The splicer will sound an error alarm indicating the problem if the splice is flawed due to any of these reasons. In this case the splice will have to be redone.

Factors that determines the success of the splice include the cleanliness of the splicer and cleaver, dust is the great nemesis of splicing, how the fiber was prepared and again if it was cleaned properly, the cleave angle and the condition of the splice machine.

The inserted fiber lies in the V-groove in the splicer and this must be spotless or misalignment might occur. Dust on the fiber might come off inside the V-groove or onto the observation cameras and effect the splice quality, it could also burn during the arc and effect the electrode life or cause an arc across the V-groove which will damage the machine. Cable jelly will do the same. It is imperative that the fiber is clean once inserted into the machine. The technician should consider environmental factors and work very carefully to avoid any dust blowing into the machine. Dust could settle on the cameras or V-groove and will adversely affect splice quality. Daily and weekly maintenance schedules should be followed. Also, as the saying goes: A splice is just as good as it’s cleave. The condition of the cleaver is imperative. Make sure cleave angles are well below 1 degree. Lastly, a splicer needs to be serviced and calibrated at least once a year – or every 3000 to 5000 arcs. An uncalibrated splicer will give a bad splice result. Motor alignment might be affected and a fraction of a millimeter will have a negative effect on the splice quality. Electrodes are consumable and have a limited arc life.

The life of Fujikura electrodes ranges between 3000 and 5000 arcs depending on the splicer model and environmental conditions. Make sure about the recommendations for your model on purchase. Dusty or humid conditions will reduce the life of the electrodes. The splicer has a specific procedure when replacing electrodes. Firstly, use genuine Fujikura parts or take the unit to an accredited calibration center. Use the ‘Replace Electrodes’ program in the maintenance menu on the splicer and be careful not to overtighten any screws. The splicer will melt fibers ends inserted on the left and right side of the V-grooves and scatter the glass over the tips of the electrodes in order to sharpen them and protect them. Worn electrodes lose this sharp edge and an angled arc will occur. The resultant imperfect splice will not be immediately detected; however, an angled arc could reduce the life of the splice by up to 80%!

Fujikura offers several precision cleaver models. The purpose of the cleaver is to score the fiber and then to break it with a small cleave-angle. This is imperative to achieve a good splice. A good cleave-angle is typically below 0.5 degrees; however, anything under 1 degree is acceptable. The cleaver has a rotating blade that can do up to 48000 cleaves. The cleaver must be kept spotless and once again daily and weekly maintenance is recommended. Fujikura recommends that the fiber-plate, rubbers, anvil and blade should be cleaned every day before use. The Fujikura CT-30 cleaver offers precise cleaving as well as automated ‘fiber collection to bin’. This is the flagship cleaver. The cleaver should also be serviced yearly and the blade should be checked by a professional.

Fujikura offer a range of splice machines these days. They all have different features for different applications i.e. Core-alignment, Variable V-groove Adaptive Core Alignment, and Fixed V-groove.

Fujikura’s Core-alignment splicers are the most accurate. These machines are made for seamless speed and accuracy. Core-alignment splicers can be used in any application; however, they are bulkier and heavier than the smaller models. Maximum splice loss in the field is 0.02dB; however typical splice loss across the splice is around 0.01dB. Core-alignment splicers align the actual core of the fiber and will compensate for dust on the V-grooves or misaligned fiber. Modern Fujikura core-alignment splicers can align the core of G.657 (Bend Insensitive Fiber) and can produce a low splice-loss splice on these type of fibers as well as mismatched fibers, i.e. G.652 (SM) and G.657 (BIF). Fujikura core-alignment splicers include the Fujikura-70S and Fujikura-62S. The 70S is Fujikura’s flagship model and the highest-end splicer on the market and is the only unit that offers automated Wind Protector covers, Sheath Clamps and Heater operation.

Fujikura’s Variable V-groove Adaptive Core Alignment splicers are more suited for aerial and FTTx installations. Maximum splice loss in the field is 0.03dB; however typical splice loss is 0.02dB or less. Variable V-groove Adaptive Core Alignment splicers aligns the logical center of the core of the fiber using a cladding / core ratio algorithm and will compensate for dust on the V-grooves or misaligned fiber. Fujikura models includes the Fujikura-22S. This splicer is lightweight build for portability and quick deployment.

Fujikura’s Fixed V-groove splicers are small, lightweight and easily deployable. This splicer does not align the fiber on a X-, Y-axis, it joins the fiber as is on the Z-axis. Accuracy is determined by the cleanliness of the V-grooves and the quality of the fiber. Low quality fiber might have an off-center core and this might cause a bad splice; however, this phenomenon is very uncommon with today’s modern fiber. The Fujikura-12S is used in Areal, FTTx and for purely connectorizing applications.

All Fujikura splice machines come with environmental protection i.e. dust and rain proof features as well as shock resistant features. The glass covering the screen is tempered glass and very robust and the Fujikura-70S model is the world’s only 6-directional drop proof unit.

When purchasing a new splice machine, it is recommended you consider the following:

  1. Never consider buying a grey (parallel import) product. You won’t have any support and the warrantee will be void. Find the accredited distributor and as for confirmation.
  2. Brand and country of manufacture. Like with anything, consider a reputable brand and avoid anything uncommon. I strongly recommend considering Japanese products as they have a very respectable reputation in the world market. Japan is synonymous with quality products and they offer good aftersales service. The world market reveals which are the most popular brands. Be careful of the cheaper brands as it is a proven fact that some brands work well new; however, the splice quality soon deteriorates. This is due to inferior electronics, especially the arc-discharge unit. The arc-discharge unit is the component that creates the 8000Volt DC arc across the electrodes.
  3. Investigate and confirm that the distributor offers aftersales service in the form of an accredited calibration lab and that service and repairs are done swiftly. The distributor must carry spares and have properly trained technicians. The last thing you want is an untrained techy doing the trial-and-error on your investment. A splice machine is an electro-mechanical unit with many moving parts. Be wary of distributors who offer cheap and quick services. To calibrate and test a splice machine is a timeous job and the trained technician doing the job will not come cheap. Be prepared to pay more to ensure that you can take your splice machine into the field without issues. Proper service also affects the longevity of the unit.
  4. Check service intervals and consumables. Different brands and models offer different specification on electrode life, etc. You want something that will do many splices before service is necessary.
  5. Look at the integrity of the supplier and distributor. Will they look after you in the long-run? Do they have a specific aftersales division on the equipment? Do they offer free training? Be careful of suppliers that sell many products and their splicer range is just an add-on. Buy from people whom features the product as a core product in their range of products.
  6. Remember, a splice machine is an investment and most likely your livelihood. Put your family’s lives in good hands by buying a quality product that can put food on the table for a long time. The same goes for companies – unnecessary equipment maintenance costs can eat deep into profits.

Please feel free to contact me at IC Logistix (Pty) Ltd for any assistance in choosing the right product for your needs. Zach Yacumakis +2711 521 2353, zachy@iclogistix.co.za and remember: Work creatively! Work with a sense of challenge! And never give up! This is what makes up “Fujikuraisum.”

 

 

 

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