Method for regulating emitting light power in PON (Passive Optical Network), OLT (Optical Line Terminal) and system

The invention provides a method for regulating the power of emitting light in a PON (Passive Optical Network), an OLT (Optical Line Terminal) and a system. The method comprises the steps of for each ONU (Optical Network Unit), calculating the receiving light power of light sent to the ONU by the OLT; for each ONU, sending a message for reducing the emitting light power to the ONU when the OLT finds that the receiving light power of the light sent to the ONU by the OLT is greater than the lowest overload laser power configured in the OLT; sending a message for increasing the emitting light power to the ONU when the OLT finds that the receiving light power of the light sent to the ONU by the OLT is smaller than the lowest receiving sensitivity configured in the OLT. According to the method disclosed by the invention, the regulation on the emitting light power of the ONU and the OLT can be realized.