Patent ID: 7409164

Claim:
A passive optical network comprising: an optical line termination for generating multiple downward optical signals; and multiple optical network units for receiving said downward optical signals, wherein each optical network unit comprises: a receiver for converting a corresponding downward optical signal inputted from the optical line termination into a first voltage signal and outputting the first voltage signal; and a transmitter for calculating a distance to the optical line termination from an intensity of the first voltage signal outputted from the receiver and generating an upward optical signal having an intensity adjusted according to the calculated distance to the optical line termination, wherein the transmitter comprises: a second limiting amplifier for amplifying a second voltage signal; a laser diode for converting the second voltage signal into the upward optical signal; a peak detector for calculating an intensity of the first voltage signal inputted from the preamplifier; a first APC circuit for controlling an intensity of the upward optical signal generated by the laser diode according to the intensity of the first voltage signal; a temperature compensation circuit for compensating for temperature changes of the laser diode; and a second APC circuit for controlling the upward optical signal generated by the laser diode such that it may have a substantially constant intensity.