Optical Power Splitter Calculator
Estimate optical splitter output per branch from split ratio, insertion loss, excess loss, connector loss, splice loss, input dBm, receiver target, and design margin.
🖧PON and splitter presets
⚙Splitter inputs
Used only when the split ratio dropdown is set to custom.
Use measured splitter input power or worst-case OLT launch after feeder loss.
For uniform PLC splitters this should include theoretical split plus manufacturing loss.
📊Splitter spec grid
📚Common optical splitter loss table
| Splitter ratio | Ideal split loss | Typical PLC insertion loss | Common planning use |
|---|---|---|---|
| 1:2 uniform | 3.01 dB | 3.4 to 3.8 dB | Lab balance, small tap stage |
| 1:4 uniform | 6.02 dB | 7.0 to 7.4 dB | Cabinet or first cascade stage |
| 1:8 uniform | 9.03 dB | 10.2 to 10.8 dB | Small FTTH serving area |
| 1:16 uniform | 12.04 dB | 13.4 to 14.0 dB | Building or floor splitter |
| 1:32 uniform | 15.05 dB | 16.8 to 17.5 dB | Common GPON split design |
| 1:64 uniform | 18.06 dB | 20.0 to 21.0 dB | XGS-PON or dense FTTH |
| 1:128 uniform | 21.07 dB | 23.5 to 24.5 dB | High budget PON only |
🔌Connector, splice, and branch allowance table
| Branch component | Typical loss | Conservative input | How to count it |
|---|---|---|---|
| SC/APC mated pair | 0.2 to 0.5 dB | 0.5 dB per pair | Splitter port, patch panel, ONT end |
| LC/UPC mated pair | 0.2 to 0.5 dB | 0.5 dB per pair | Lab and active equipment patches |
| Fusion splice | 0.05 to 0.1 dB | 0.1 dB each | Distribution, drop, and repair splices |
| Mechanical splice | 0.2 to 0.5 dB | 0.3 dB each | Use when no fusion test data exists |
| Drop cable allowance | 0.2 to 2.0 dB | Use measured OTDR loss | Route fiber plus small bends and patches |
| Port uniformity | 0.6 to 1.5 dB | Worst-port delta | Subtract from weakest branch margin |
📡PON receiver planning table
| System class | Common wavelength | Receiver planning target | Splitter note |
|---|---|---|---|
| GPON Class B+ | 1490 nm downstream | About -28 dBm sensitivity | 1:32 is common when feeder loss is modest |
| GPON Class C+ | 1490 nm downstream | About -32 dBm sensitivity | Supports longer routes or larger split loss |
| XGS-PON N1 | 1577 nm downstream | About -28 dBm sensitivity | Use careful loss records for 1:64 designs |
| XGS-PON N2 | 1577 nm downstream | About -29 to -31 dBm | Higher budget for dense split plans |
| 1550 RF overlay | 1550 nm downstream | Depends on optical receiver | Keep optical power in receiver window |
| Lab photodiode | Any test band | Use instrument minimum level | Check both average and worst branch power |
🏠Common splitter design table
| Design pattern | Typical split | Added branch elements | Margin focus |
|---|---|---|---|
| Small FTTH cabinet | 1:8 PLC | 2 connectors, 2 splices | Drop cable and connector cleanliness |
| Neighborhood GPON FDH | 1:32 PLC | 2 to 4 connectors, several splices | Splitter loss and branch uniformity |
| Dense XGS-PON serving area | 1:64 PLC | High split plus drop loss | Use stronger optics and reserve margin |
| Cascaded cabinet design | 1:4 then 1:16 | Two splitter stages plus patching | Add both splitter insertion losses |
| Optical monitor tap | 95/5 or 90/10 | Tap branch and through branch | Confirm which port feeds the receiver |
| RF video overlay | 1:16 to 1:32 | 1550 nm split and drop plant | Keep optical receiver in its input window |
The optical power levels that reach each destinations will not be the same that entered the fiber network. Optical power levels will decreases as the signal travels down the fiber network. When the signal pass through a splitter, the optical power levels will divide and, therefore, become lower for each split of the signal.
Additionally, each connector, splice, and length of fiber within the network will further reduce the optical power of the signal. A working link will be established when the weakest optical power level at each destination is higher than a minimum level required by the receiver to recognize the signal. The calculator will do the math for you once you have entered the type of splitter that will be use, the optical power that will enter the network, and the amount of downstream loss that will occur in the network.
How Light Loses Power in a Fiber Network
However, you must understand why these values exists within the calculation to properly plan the fiber network that you are to create. The split ratio will determine the number of ways that the splitter will divide the light, and the split ratio will determine the theoretical loss of that signal. The theoretical loss will follow the division of the signal, but there will be additional loss due to the components of the network.
An example of such loss may be an optical splitter that indicates a loss of 17 dB, even though the calculation of the mathematical loss is only 15 dB. The extra 2 dB of loss is to ensure that the signal maintains its strength across a variety of temperature within which the network will be deployed. Connector loss is another element that many people dont think of as one of the losses in the network.
Each connector will have a loss of optical power, but it may be small in the numbers that is written. Between two or three of these connectors between the splitter and the ONT may result in the loss of one full decibel of optical power. Much of the loss in the network will also be due to the splices used in the fiber.
Each fusion splice will lose no more than 0.1 dB of optical power. However, the distribution cable may have numerous fusion splices if the network crosses numerous streets. Additionally, there will be a drop cable allowance for the final run of the network to the customer.
This allowance also includes the bends in the drop cable. Each of these components will impact the optical power levels reaching each destination along the network. This is one of the reasons why a uniformity value is asked of you in the planning of the network.
The sensitivity of the receiver will determine the minimum optical power level that will be required for each of the signals that enter the network. GPON Class B+ optics requires a minimum level of power of minus 28 dBm. For XGS-PON designs, the level can be minus 29 dBm or minus 30 dBm.
This value will be used to determine the margin of optical power that will be used within the network. Decibels can be lost with aging of the network components, shifts in temperature of the network, and dirty network connectors. Most networks will have a margin of three decibels of optical power.
Some may have a margin of one or two decibels of optical power, though this margin will leave the network with little flexibility in the face of changes in the network. Most mistakes are made in focusing on the average optical power level of each branch of the network rather than the weakest branch. The network might work when focusing only on the average branch power levels.
However, the customer located at the terminal with the weakest optical power may experience errors in data recognition. The calculator allows you to separate these two values. If the calculator indicates that the network fail to meet the requirements of the customer receivers, it is due to the downstream losses in the network.
In this case, using a stronger transmitter will not fix the problem. Instead, you should reduce the loss in each branch of the network. If using cascaded splitters in the network, there will be additional loss within the network due to the number of these components.
Using two cascaded splitters may result in a loss that is more than the loss of the individual components due to the number of splits and the number of losses at each split. Using cascaded splitters will result in a fasterer growth of total loss in the network. Some may prefer using a single, large splitter over cascaded splitter networks because the single, large splitter will reduce the total loss in the network, even if it takes up more space within the cabinet in which it is installed.
The calculator will allow you to compare these two options. The wavelength of the signal will impact the loss of optical power within the network. If the splitter is set up to work at 1490 nm of wavelength, it will exhibit a different level of loss than if it were to operate at 1577 nm or 1550 nm wavelengths.
Even a half decibel of loss at this wavelength can create the difference between a successful network and a failed network. The wavelength selector within the calculator will allow you to choose the appropriate wavelength for your network, which will load the appropriate receiver target into the calculator. The last and final way of determining if the optical power levels of your network are correct is through field measurements.
While the optical power losses that are calculated in the network are based off the manufacturer’s specification for the components of the network, the field measurements will provide the true optical power loss within the network. Use field instruments to measure the optical power of the signal entering the splitter and the weakest of the output ports from that splitter. A low reading of optical power at that terminal may mean that the feeder losses in the network are higher than expected, or there are dirty connectors or faulty splitter ports.
The value of the optical power calculator is that it makes you list every loss element in the network prior to beginning construction of the network. Once you have listed every loss element, you can decide which single loss element will create the most improvement in the network if corrected. By listing every loss element in the network, you can create a reliable network design that will not require as many maintenance visit to fix any problems.
