Two-color laser diode for 54-Gb/s fiber-wired and 16-Gb/s MMW wireless OFDM transmissions

Abstract

A two-color, laser-diode-based, full-duplex fiber-wired and millimeter-wave (MMW)-wireless orthogonal frequency-division multiplexing (OFDM) transmission link is performed. With modal control on the two-color laser diode, a single-wavelength optical carrier is used as both the downstream and upstream transmitters to replace the dual-mode one with an optical baseband, which effectively suppresses the chromatic dispersion that occurs in fiber. The proposed system demonstrates a carrier-reused, full-duplex 28-GHz MMW dense wavelength division multiplexing passive optical network (DWDM-PON) system, providing OFDM transmission with 54 Gb/s downstream, 36 Gb/s upstream and 16 Gb/s wireless data rates. The single-wavelength optical carrier transmits data from an optical line terminal (OLT) to a remote node (RN) and then transfers into a dual-wavelength carrier for optically heterodyne beating an MMW carrier, which further wirelessly transmits the data to an optical network unit (OUN). In addition, the upstream data is carried by another slave colorless laser diode injection-locked by reusing the downstream carrier without additional data erasing, which avoids the wavelength selection problem that resulted from identifying or addressing upstream and downstream channels. Among three laser transmitters with different cavity lengths, the 600-μm embedded MMW wireless carrier can provide the lowest bit error rate (BER) after 25 km of fiber and 1.6-m free-space transmissions at 16 Gb/s, because its highest external quantum efficiency supports the optimization on self-heterodyne transferring the MMW carrier to enable the low-noise and long-distance wireless transmission.