Patent ID: 9246628
Filing Date: 2016-01-26
CPC Classification: H04J

Claim Text:
1. An optical line terminal (OLT) of a hybrid passive optical network (PON) system, the OLT comprising: a seed light source configured to provide a seed light having a predetermined wavelength; an optical transmitter configured to modulate the seed light generated from the seed light source using a reflective modulator, and to transmit a modulated orthogonal frequency division multiplexing (OFDM) downstream optical signal to a plurality of optical network units (ONUs); and an optical receiver configured to receive an OFDM upstream optical signal from the at least one ONU, wherein the plurality of ONUs is configured to obtain a wavelength of the OFDM upstream optical signal from the OFDM downstream optical signal and to reuse a portion of the OFDM downstream optical signal as the OFDM upstream optical signal, wherein the plurality of ONUs is configured to share one OFDM subcarrier associated with the OFDM downstream optical signal by time division multiplexing (TDM), to obtain a wavelength of the OFDM upstream optical signal from the OFDM downstream optical signal, and to reuse a portion of the OFDM downstream optical signal as the OFDM upstream optical signal, wherein the at least one ONU comprising: an optical coupler configured to branch an orthogonal frequency division multiplexing (OFDM) downstream optical signal transmitted from an optical line terminal (OLT); an optical receiver configured to receive a portion of the OFDM downstream optical signal through the optical coupler; and an optical transmitter configured to modulate the remaining portion of the OFDM downstream optical signal through the optical coupler using a reflective modulator and to transmit a modulated OFDM upstream optical signal to the OLT, wherein the optical coupler configured to adjust the distributing ratio to increase the downstream optical signal supplied to the optical transmitter when the optical link length or the optical link power budget is increased.