Title :
Symmetric 10-Gb/s WDM-PON Using Directly Modulated Lasers for Downlink and RSOAs for Uplink
Author :
Al-Qazwini, Zaineb ; Kim, Hoon
Author_Institution :
Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore, Singapore
fDate :
6/15/2012 12:00:00 AM
Abstract :
We demonstrate a cost-effective, 10-Gb/s full-duplex wavelength-division-multiplexed passive optical network over 20 km single-feeder fiber using a single light source per optical network unit (ONU). We exploit a directly modulated laser (DML) and a reflective semiconductor optical amplifier (RSOA) for downlink and uplink, respectively. In this system, a nonreturn-to-zero (NRZ) downstream signal is first frequency up-converted to around 20 GHz before being fed to a DML for downstream transmission. After transmission over the feeder fiber, a portion of the downstream signal is detected at the ONU and the other portion is fed to the RSOA as seed light. The RSOA is directly modulated by a 10-Gb/s NRZ signal for upstream transmission. To overcome the bandwidth limitation of the directly modulated RSOA, we employ an optical delay interferometer at the upstream receiver. The passive optical device acts as an optical equalizer and enables the 10-Gb/s upstream signal to be accommodated with a 1.3-GHz-bandwith RSOA. We investigate through experiment the crosstalk between the downstream and upstream signals as a function of the downstream subcarrier frequency. Also investigated in this paper is the nonlinear frequency mixing of the downstream and upstream signals in the RSOA.
Keywords :
fibre lasers; light interferometers; optical fibre amplifiers; optical receivers; passive optical networks; wavelength division multiplexing; DML; NRZ downstream signal; ONU; RSOA; bandwidth 1.3 GHz; bit rate 10 Gbit/s; directly modulated lasers; downstream subcarrier frequency; downstream transmission; full-duplex wavelength-division-multiplexed passive optical network; nonlinear frequency mixing; nonreturn-to-zero downstream signal; optical delay interferometer; passive optical device; reflective semiconductor optical amplifier; single light source per optical network unit; single-feeder fiber; size 20 km; symmetric WDM-PON; upstream receiver; upstream signal; upstream transmission; Amplitude modulation; Bandwidth; Optical fibers; Optical filters; Passive optical networks; Direct modulation; directly modulated laser (DML); passive optical network (PON); semiconductor optical amplifier; wavelength-division multiplexing (WDM);
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2012.2190975