Optimisation of SOA-REAMs for Hybrid DWDM-TDMA PON Applications

Abstract

We demonstrate how loss-optimised, gain-saturated SOA-REAM based reflective modulators can reduce the burst to burst power variations due to differential access loss in the upstream path in carrier distributed passive optical networks by 18 dB compared to fixed linear gain modulators. We also show that the loss optimised device has a high tolerance to input power variations and can operate in deep saturation with minimal patterning penalties. Finally, we demonstrate that an optimised device can operate across the C-Band and also over a transmission distance of 80 km.

Efficient modulation cancellation usingreflective SOAs

“…Because of the strong gain saturation, the RSOA experiences a large gain reduction by 28 dB at an input power of about 0 dBm. Further increases in input power results in such a large gain saturation that the output power decreases with increasing input power, this is consistent with the results in [7,10]. To illustrate this point further, the steady-state, spatially resolved counter-propagating waves and carrier densities are plotted in Fig.…”

Improved reduced models for single-pass and reflective semiconductor optical amplifiers

“…The RSOA length was taken to be 800 µm when implementing the TWM. There is excellent agreement between the obtained input-output power transfer characteristics from both models and both models replicate the findings of RSOA with differing values of reflectivity [10]. The remarkable thing is that there is considerable overlap between the curves with a maximum discrepancy of 1 dB despite the fact that the reduced RSOA model neither considers spatially-resolved counterpropagating fields nor spatially resolves the gain profile.…”

“…In general, the output power characteristics of reflective amplifiers differ from single pass amplifiers in that a maximum output power is reached at a certain input power [11], and this was shown experimentally and numerically for RSOAs [10], [12]. Simplified travelling wave models for RSOAs have appeared [3], [4], with the model in [3] introducing a lumped RSOA model that shows nice agreement with the full travelling wave model in [4].…”

“…RSOAs are finding applications as low-cost upstream transmitters within PONs [5]- [6], [10]; therefore targeting accurate, yet simple, models that describe their behavior is a laudable goal for system analysis simulations. In general, the output power characteristics of reflective amplifiers differ from single pass amplifiers in that a maximum output power is reached at a certain input power [11], and this was shown experimentally and numerically for RSOAs [10], [12].…”

“…Using Eqs.-(15) and (16) we now present results of RSOA gain saturation for CW input signals varying from -30 to +10 dBm for with reflectivity R ( 21 0 R    dB) set to mimic the experimentally obtained curves in [10]. The calculated results in Fig.…”