Abstract: Technology to provide linked control of bandwidth allocation to a plurality of optical network units among the plural wavelengths by a bandwidth allocation section coupled to the plural optical network units.

Abstract: In a gain-switching-type transimpedance amplifier, in order to provide a technique capable of preventing unnecessary gain switching caused when noise is received, and preventing decrease in sensitivity caused when noise with a large input level is received, and then, a burst signal with a small input level is received, a transimpedance amplifier 5 includes: a pre-amplifier 200 to which the burst signal is inputted; an average detection start determination unit 300 for comparing an output of a pre-amplifier 200 with a first threshold voltage; an average detection circuit 400 for detecting and outputting an average value of the output of the pre-amplifier 200 during a certain period of time from a time point when the output of the pre-amplifier 200 exceeds the first threshold voltage; and a gain switching control unit 500 for determining whether to switch a gain of the pre-amplifier 200 based on an output of the average detection circuit 400.

Abstract: There is a need to provide a multirate burst mode receiver for an OLT to be capable of receiving a high-speed burst signal without the need for a special capability of an ONU in a PON system including a mix of ONUs at different transmission bit rates. A multirate burst mode receiver according to the invention includes a signal input discrimination section and a bit rate discrimination section. The signal input discrimination section detects an average amplitude to discriminate signal input. The bit rate discrimination section detects an envelope curve for a high-frequency component to discriminate a signal bit rate. Based on a discrimination result from the signal input discrimination section and the bit rate discrimination section, the multirate burst mode receiver switches a setting for an optical signal reception section and a serial-parallel converter corresponding to the reception bit rate.