Patent ID: 6901222

Claim:
A PON system comprising: a terminal device; a plurality of subscriber terminals; at least one star coupler provided according to number of said plurality of subscriber terminals; an first optical fiber transmission line connecting said terminal devices and said at least one star coupler; and a plurality of second optical fiber transmission lines connecting said plurality of subscriber terminals and said at least one star coupler; said terminal device comprising a first light source for outputting a first optical signal to said first optical fiber transmission line; each of said plurality of subscriber terminals comprising: a second light source; a drive circuit for supplying a drive current to said second light source so that said second light source outputs a second optical signal to one of said second optical fiber transmission lines; a photodetector receiving said first optical signal from said one of said second optical fiber transmission lines; an amplitude detecting circuit detecting the amplitude of an output from said photodetector; and a control circuit decreasing and increasing said drive current according to an increase and decrease in the amplitude detected by said amplitude detecting circuit, respectively; wherein each transmitting power of said plurality of subscriber terminals is controlled according to each receiving power of said plurality of subscriber terminals, thereby increasing dynamic range of the transmitting power of each of said plurality of subscriber terminals.