Patent ID: 7471899

Claim:
A wavelength division multiplexing passive optical network (WDM-PON) system based on a wavelength-tunable external cavity laser (ECL) light source, the WDM-PON system comprising: an optical line terminal (OLT) comprising an optical transmitter in which a first wavelength-tunable waveguide Bragg grating (WBG) is formed, which is composed of a first ECL array generating optical wavelengths for data transmission, and an optical receiver composed of a photo diode (PD) array, wherein the optical transmitter further comprises a first WDM multiplexer (MUX) multiplexing a plurality of optical wavelengths output from the first ECL array and the optical receiver further comprises a first WDM demultiplexer (DMX) receiving a multiplexed optical wavelength and dividing the input multiplexed optical wavelength into a plurality of optical wavelengths; a plurality of optical network terminals (ONTs), each ONT comprising an optical receiver receiving an optical wavelength for data transmission transmitted from the OLT and an optical transmitter in which a second wavelength-tunable WBG is formed, the optical transmitter composed of a second ECL generating, independently of a received downstream optical wavelength, a wavelength-tunable optical wavelength for upstream transmission, the optical transmitter further comprising a phase controller located between an active region of the second ECL and the second WBG, the phase controller to receive an injected current to compensate for a variation in a bias current injected into the active region, each ONT also comprising a wavelength controller to control a temperature applied to the second wavelength-tunable WBG based on wavelength control data received from the OLT and an optical power output from the second ECL; a second WDM DMX, which is located in a main distribution frame (MDF) placed near the plurality of ONTs, divides a multiplexed optical wavelength transmitted from the first WDM MIUX via an optical fiber into the plurality of optical wavelengths, and connects each optical wavelength to a relevant ONT of the plurality of ONTs; and a second WDM MUX, which is located in the MDF placed near the plurality of ONTs, multiplexes a plurality of optical wavelengths output from optical transmitters of the plurality of ONTs, and transmits the multiplexed optical wavelengths to the first WDM DMX of the OLT via an optical fiber, wherein the wavelength-tunable optical wavelength for upstream transmission is determined by a physical location of an input port of the second WDM MUX located near the ONT.