Patent ID: 7599411
Filing Date: 2009-10-06
Classification: G02B,H04J

Abstract:
1. A wavelength division multiplexing passive optical network (WDM-PON) system with an optical wavelength alignment function, the WDM-PON system comprising: an optical line terminal (OLT) composed of an optical transmitter, which is composed of an OLT-LD array generating optical wavelengths for data transmission and a first wavelength control circuit aligning wavelengths of downstream transmission channels against variations of ambient temperatures, and an optical receiver, which is composed of a photo diode (PD) array and a second wavelength control circuit aligning a wavelength of an upstream transmission line against variations of ambient temperatures, wherein the optical transmitter further comprises a first WDM multiplexer (MUX) multiplexing a plurality of optical wavelengths output from the OLT-LD 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 individual wavelengths; a plurality of optical network terminals (ONTs), each ONT comprising an optical receiver, which receives a downstream optical wavelength for data transmission transmitted from the optical transmitter of the OLT, and an optical transmitter in which a wavelength-tunable waveguide Bragg grating (WBG) is formed, which forms an external cavity laser (ECL) generating a wavelength-tunable optical wavelength by controlling a temperature applied to the wavelength-tunable WBG; a second WDM DMX, which is located in a main distribution frame (MDF) placed near the plurality of ONTS, divides multiplexed optical wavelengths transmitted from the first WDM MUX via optical fiber into individual optical wavelengths, connects each optical wavelength to a relevant ONT of the plurality of ONTs, and has a first OPM-reflection mirror (RM) port reflecting an optical wavelength transmitted from the first wavelength control circuit; 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, transmits the multiplexed optical wavelengths to the first WDM DMX of the OLT via optical fiber, has a second OPM-RM port reflecting an output optical wavelength of the OPM-LD transmitted from the second wavelength control circuit, and has a WMD-RM port reflecting optical wavelengths to the optical transmitters of the ONTs according to how an optical wavelength output from the optical transmitter of an ONT is mismatched to a corresponding pass band of the second WDM MUX.