Using an optical receiver with DTLA for upstream signal detection overcame significant obstacles related to the injection power into the RSOA and the ER of the downstream signal, which were previously considered limitations of the wavelength remodulation scheme. Even though the extinction ratio (ER) of the downstream signal was as much as 9 dB and the injection power into the RSOA at the optical network unit was about −24 dBm, we successfully obtained error-free transmission results for the upstream signal through careful control of the decision threshold value in the optical receiver located at optical line terminal (OLT). We have experimentally demonstrated that the use of an optical receiver with decision threshold level adjustment (DTLA) improved the performance of an upstream transmission in reflective semiconductor optical amplifier (RSOA)-based loopback wavelength division multiplexing-passive optical network (WDM-PON).
Feasibilities of those schemes are discussed in the view of commercial application to WDM-PON. Three schemes are presented the simplest one is to use the RSOA gain saturation, the second uses the effect of frequency detuning on the extinction ratio of optical signal, and the third uses RSOA gain control by dynamically varying the current injection.
The major advantage of remodulation schemes is the possibility of realizing the simplest WDM-PON optical link structure, which is directly reflected in cost-effectiveness of the network both in equipment and maintenance.
#AL MEDIA CONVERTER SERIES#
The remodulation schemes have a common feature that the optical signal modulated with downstream data is reused to carry the upstream data through the RSOA in the subscriber-side equipment by a series of processes such as being flattened out, reflected at the rear facet of the RSOA, and then remodulated with upstream data. This article presents remodulation schemes with reflective semiconductor optical amplifiers (RSOAs), which have recently been developed for application to the wavelength-division-multiplexed passive optical network (WDM-PON).
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