Optical Splitter Light Attenuation And Calculation Method

In the optical network topology, the appearance of the optical splitter helps the user to maximize the network performance. An optical splitteris a passive optical device that can decompose an optical signal into multiple optical signal outputs, including one or two input ends and multiple output ends. When the optical network system needs to couple and distribute the optical signal, an optical splitter can be used to realize it. This article contains the following: Optical splitter light attenuation and calculation method.

Optical power loss is related to the number of optical branches (each 1:2 split produces a loss of ~3.5dB) • The loss of optical power determines the transmittable distance • Bandwidth vs. cost: The available bandwidth per household depends on The size of the optical splitting ratio, the larger the optical splitting ratio, the lower the cost per household of the OLT.

As we all know, the four most important parameters of the optical splitter are: wavelength, insertion loss, additional loss and splitting ratio, but in fact, the most important performance index of the optical splitter is the optical splitter under a specific splitting ratio. Different light decays, in the case of different split ratios, the light decay of the optical splitter will also be different. So how to calculate the optical attenuation of the optical splitter? Optical attenuation value of optical splitter = transmit optical power + additional loss + insertion loss + bare fiber loss.

Spectral Ratio Calculation

Formula: ki=Pi/SP*100%

Among them, Pi is the driving power required by each optical link, and SP is the sum of the required driving power of each optical link carried by the laser.

Note: In actual use, the manufacturer has indicated the splitting ratio, such as 1/2 is 80%: 20% or 70%: 30%; 1/3 is 70%: 15%: 15%; 1/4 is 70%: 10 %: 10%: 10%.

Additional Loss Calculation

In the process of actual operation, the measurement of the additional loss value can be carried out, and it is only necessary to carry out the detection and recording of the value according to certain operation specifications, and to do a good job in the classification of different links.

Generally, the loss of 1×N single-mode standard optical splitter is as follows:

Insertion Loss Calculation

Formula: IL=-10lg(Po/Pi)

Among them, Po is the optical power at the output end, and Pi is the optical power at the input end.

Note: Po/Pi in the formula is equivalent to the splitting ratio of the optical splitter, namely: IL=-10lg(ki). For example, there is a one-to-two beam splitter, which is a two-to-eight beam splitter, that is, the splitting ratio is 20%:80%. Its 20% optical link insertion loss theoretical value is -10lg (20%), which is approximately equal to 6.99dB.

Bare Fiber Loss Calculation

Fiber loss generally decreases with increasing wavelength. In actual operation, this value does not need to be calculated, and there is a certain reference standard. It is necessary to strictly refer to the numerical standard, and measure the loss values of different wavelengths to determine the final loss value.

Note: Connector attenuation: generally each is 0.5dB.

The calculation method of the optical splitter loss is mentioned above, so someone will ask: how to measure the optical splitter loss? First of all, when the optical signal is transmitted through the optical splitter, the loss value has nothing to do with the transmission direction. Whether the optical signal is transmitted from the input end of the optical splitter downstream to the output end or upstream from the output end to the input end, the loss value is the same in both directions of transmission. Therefore, we only need to measure the loss value in one direction of the optical splitter.

Below, we take a simple 1x2 optical splitter as an example to measure the loss in the downstream direction of the optical splitter, as shown in the figure below. First, use the test fiber jumper to connect the light source and the optical power meter, set the reference value, then use the test fiber jumper to connect the light source and the input end of the optical splitter and connect the optical power meter to the output end of the optical splitter, measure the first The loss value of one output port, then use the same method to measure the loss value of the second output port, and finally the loss of the optical splitter can be obtained through the calculation formula.

Similarly, the above method can also be used to measure the loss in the upstream direction of the optical splitter. The difference is that the light source is connected to the output port of the optical splitter, and the optical power meter is connected to the input port, as shown in the figure below.

For other 1xN optical splitters, such as 1x32 optical splitters, the above measurement method can also be used, we just need to set the light source at the input port of the optical splitter, and then measure each output in turn using a power meter and a test fiber patch cord port loss.

In addition, for the loss measurement of 2X2 optical splitter, the above method is also applicable. First, measure the loss from one input port to the two output ports, and then measure the loss from the other input port to the two output ports. Similarly, this method can also be used to measure the loss of a 2xN optical splitter, but the measurement process is more complicated and requires more values to be recorded.

Note: Because the optical splitter will produce additional loss and connector loss during the manufacturing process, there will be slight differences between the measurement results and the actual optical splitter loss value.