Optical Fiber Splice Loss and Methods to Reduce It

July 11, 2021

Fiber fusion splicing is a very important part in network projects. It splices 2 fiber ends together and it also causes optical fiber splice loss. So, the reduction of fusion splicing loss is something that every constructor needs to consider. In this article, HOC will look at few methods to avoid failures in the network and reduce fiber fusion splicing loss.

HOC (Hone Optical Communications) has 19+ years on optical communications and ODN. Let’s get started.

Optical Fiber Splice Loss

The certain amount optical loss of optical fiber transmit to the connection after splice is known as optical fiber splice loss. It is mainly caused by the transmission loss of optical fiber itself and the splice loss at splice point. As mentioned above, fiber fusion is very important in networks. So, we need to minimize the optical fiber splice loss.

Reduce Splice Loss

From the related fiber fusion splicing materials and operation. We can have a detailed idea of how to reduce the optical splice loss.

Fiber Consistent

Try to use the same batch of high-quality optical fibers on a fiber optic cable line is necessary. For the same batch of fibers, they will basically have the same mode field diameter. After the fiber is disconnected at a certain point, the mode field diameter between the two ends can be regarded as the same. Splice fusing at the disconnection point can minimize the influence of the mode field diameter on the fiber fusion splicing loss.

Therefore, optical fiber cable manufacturers are required to use the same batch of optical fibers to produce continuously according to the required optical cable length, mark with serial number and distinguish A and B ends on each reel, and skipping number is strictly disallowed.

When laying the fiber optic cables, cable must be laid out in the order along the route determined by their number and ensured to be that the B end of the front optical cable is connected to the A end of the next optical cable. As a result, we can ensure that the connection can be welded at the disconnection point, and reach the smallest splice loss value.


In the installation of optical cables, small loops, bending and twisting of fiber cables are strictly prohibited. So, long-distance optical fibers need to be constructed by multiple people at the same time. And 6 to 8 walkie-talkies should be equipped on construction site. The cable laying method of carrying cable on shoulder and following with personnel can effectively prevent the occurrence of back buckle.

The traction force is not supposed to exceed 80% of the cable pulling allowable force, and the instantaneous maximum traction force should no more than 100%. In addition, traction force should be added to the cable reinforcement.

In short, laying of the optical cable should be strictly in accordance with the construction requirements. Thereby we can minimize the probability of damage to the optical fiber during construction, and avoiding the increase of the splicing loss caused by the damage of the optical fiber core.

Standard Splicing

It is always important to choose experienced and well-trained staff for the splice operation. Because the level of splicing skill directly affects the splicing loss. The splicing operator should strictly follow the optical fiber fusion splicing process flow chart for splicing. And using OTDR to test optical loss of the splicing point during splicing process.

Those joint that do not meet requirements should be re-spliced. For points with large splicing loss, 3 to 4 times of repeated splicing is better. When splicing loss of multiple optical fibers are large, we can cut off a section of the fiber optic cable and reopen the cable for splicing.

In addition, it is best to use a branded fiber splicing machine. You can look at following fusion splicers with good reputation on the market, so you will know how to choose those fusion splicers with better brands.


The splicing operation should be carried out in a clean environment. It is strictly prohibited to operate in open air of dusty and humid environment. All parts of cable connection, tools and materials should be kept clean. And the optical fiber ends must not be damp. The cut fiber must be clean and free of dirt. After cutting, the optical fiber could not exposed to air for long time, especially in a dusty and humid environment.

Splicing Technique

Choosing a high-precision fiber cleaver to prepare the fiber end is important. The quality of the fiber directly affects splicing loss. The fiber cut should be a flat mirror without burrs and defects. The inclination of the fiber end axis should be less than 1 degree. A high-precision fiber end cleaver not only improves the success rate of fiber cutting, but also improves the quality of the fiber end face. This is especially important for fusion splices that cannot be tested by OTDR (i.e. OTDR test blind spots) , fiber maintenance and repair.

Fusion Splicer Operation

The fusion splicer should be used correctly. A fusion splicer is to splice two optical fibers together, so the correct use of the fusion splicer is also an important measure to reduce the fiber optic cable splicing loss.

According to the fiber cable for spicing, setting the splicing parameters correctly and reasonably, such as pre-discharge current, time, main discharge current, and main discharge time, etc. And remove the dust in the splicer in time during and after use. Especially the dust and fiber fragments inside of fixtures, mirrors, and V-shaped grooves.

The fusion splicer should be placed in the operation environment for at least 15 minutes before each operation. Especially in places where the placement and the use environment are quite different (such as indoor and outdoor in winter). Splicing operator should reset the discharge voltage, discharge position, and V-groove driver according to the atmospheric pressure, temperature, humidity, and other environmental conditions at that time.


And that’s some methods we can use to reduce optical fiber splice loss. Did we miss anything or you have other experiences? Write us comment or email.

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Tony Lau is technical manager and co-founder at HOC. He loves writing about content optical fiber communications, specializes in fiber optic cables, FTTH turnkey solutions, ADSS cable, and ODN networks.

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