What Is The Normal Range Of Broadband Optical Attenuation Loss?

For ordinary optical fiber broadband, the ideal range of light attenuation is -20dBm to -25dBm. If the speed is to be 200M, the light attenuation must be less than -25dBm. When the light attenuation is -27dBm, the maximum speed can only reach 100M. When -28dBm, the maximum speed can only reach 50M.

1.What is the light attenuation?

Light decay generally refers to its luminous flux. When charging the surface of the photosensitive drum, as the charge accumulates on the surface of the photosensitive drum, the potential continues to increase, and finally reaches the "saturation" potential, which is the highest potential. The surface potential will decrease with the passage of time. Generally, the potential during operation is lower than this potential. The process of this potential naturally decreasing with time is called the "dark decay" process. When the photosensitive drum is scanned and exposed, the dark area potential is still in the dark decay process; the carrier density in the light area photoconductive layer increases rapidly, the conductivity rises rapidly, forming a photoconductive voltage, the charge disappears rapidly, and the photoconductor surface potential also decreases rapidly. Call it "light decay."

2.Causes of fiber optic attenuation

a. Absorption loss: The optical signal transmitted in the optical fiber will be absorbed by the optical fiber material, causing attenuation.

b. Scattering loss: Small defects or impurities in the optical fiber will scatter the optical signal in the optical fiber, causing attenuation.

c. Optical bending loss: When the optical fiber is bent, the optical signal in the optical fiber will be attenuated due to the change of the refraction angle.

d. Loss at the core-cladding interface: The optical signal in the optical fiber will be reflected at the core-cladding interface, resulting in attenuation.

e. Core asymmetry loss: When the fiber core is asymmetric, the optical signal will be deflected, resulting in attenuation.

f. Effect of optical fiber temperature on attenuation: Temperature changes of optical fiber will cause changes in the linear expansion coefficient of the optical fiber material, resulting in attenuation of the optical signal.

When conducting optical fiber attenuation testing, the test instruments we generally use include optical power meter, OTDR, and visual fault locator.

3.How to calculate optical loss?

1)ODN full-process attenuation accounting:

The test calculates transmission indicators according to the worst value method. The transmission distance between EPON OLT and ONU should satisfy the following formula:

Optical fiber decay coefficient*Transmission distance+optical separator plug loss+activity connection head number*loss+optical cable line decaying balance ≤ EPON R/s-S/R point allows maximum decay.

2)EPON R/S-S/R point of decay range:

OLT PON port send light power 2dBm~ 7dBm, receiving light sensitivity is -27dBm;

ONU emits light power -1dBm~ 4dBm, receiving light sensitivity is -24dBm;

Considering the cost of the optical channel of 1DB, the maximum decay of the EPON system R/S-S/R is 25dB of ONU-OLT 1310nm, 25dB of OLT-ONU 1490nm.

3)Fiber fiber decay coefficient (including fixed fixed splicingloss):

(ONU-OLT, 1310nm): 0.4 dB/KM

(OLT-ONU, 1490nm): 0.3 dB/km

4)The typical value of the splitter insertion loss(uniformly spatuing, no connector loss) 

5)Activity connection head loss: each activity connector connection loss is 0.5dB.

6)Rich in optical cable line:

Transmission distance ≤5km, take 2dB

Transmission distance ≤10km, take 2 ~ 3dB

Transmission distance> 10km, take 3dB

FCST - Better FTTx, Better Life.

We have been designing, manufacturing and supplying passive components for fiber optical networks since 2003. Everything we do in FCST is designed to provide efficient, simple and innovative solutions to solve complicated tasks.

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lFTTH ODN Solution

lUnderground Cable Installation Solution

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lFiber Tools & Test Solution

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