What is the fiber link budget


What is the fiber link budget



Fiberlink budget is the maximum amount of signal loss allowed in networkapplications. A complete fiber optic link includes fibers, connectors, andsplices. Therefore, in calculating the maximum loss of optical fiber link, weshould take all these factors into account. In addition, we need to calculatethe system margin. System margin includes fiber bending and some unpredictablelight attenuation, etc., leaving at least 3dB margin.


Test link loss method

One end of the fiber under test is the light source and the other end is the optical power meter. The optical power emitted by the light source is Po. After the optical power of the optical fiber under test is weakened to Pi, (Po-Pi)is the Loss value of the fiber link under test.


If youneed to paired optical fiber link module, you need to meet the followingconditions:


RX2 Sensitivity <TX1 Power - Loss -3dB< Max Optical Input Power

RX1 Sensitivity <TX2 Power - Loss -3dB< Max Optical Input Power

 Picture 2. Transceiver application environment

For example, if your target device using the MTKP1015Z1CNN (SFP-10G-ZR), and the link loss is 15 dB (1550nm wavelength environment), our MTKP1015Z1CNN (SFP-10G-ZR) test parameters are as follows,  



TX1 Power - Loss-3dB=1.3-15-3=-16.7dBm

TX2 Power - Loss-3dB=2.1-15-3=-15.9dBm


-24 dBm < -16.7 dBm < -7 dBm

-23.5dBm < -15.9dBm < -7dBm


The result of the calculation isthat our MTKP1015Z1CNN (SFP-10G-ZR) can normally be used in a 15dB Lossenvironment. This method can predict whether the module meets the requirementsof the optical fiber link.

By Faron Xu|Position: FAE

Email: xufr@moduletek.com

Phone: 15989123646

Date: 2018.03.08


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