10-Gb/s Long-Reach PON System With Low-Complexity Dispersion-Managed Coherent Receiver

Abstract

We demonstrate 10-Gb/s transmission over more than 130 km of G.652 fiber using a simple directly modulated distributed feedback (DFB) laser and a new “chirp-managed” approach based on a low-complexity coherent receiver. The “chirp-managed” effect, which has been obtained in the past by optical spectral reshaping, is conveniently achieved here by means of simple electrical filtering of the received signal at the intermediate frequency. Due to coherent detection, the receiver sensitivity was -38 dBm at bit error rate (BER) 1/4 1.8 χ 10-3. No colored filters and no dispersion compensation (optical or digital signal processing (DSP)-based) were used at the receiver side. We show that the coherent system presented here, based on off-the-shelf components, is robust against variations of DFB chirp, local oscillator detuning, and electrical filter bandwidth over ranges wide enough to guarantee a simple and cost-effective implementation for 10-Gb/s long-reach passive optical network applications

4×10 Gb/s coherent WDM-PON system over 110 km of Single Mode Fibre and with 55 dB ODN power budget

“…Here a similar CM effect is very simply obtained by matching the modulation depth of the DMLs (yielding about 5 GHz dynamic chirp) with electrical low-pass filters of suitable slope in each of the three photodiode current paths (see LPFs in Fig. 1) [7]. In this proof-of-concept experiment, the EFs were implemented by using a built-in digital low pass filter function (3 GHz bandwidth, Gaussian shape, and linear phase) in the RTO before envelope reconstruction; in a real-time implementation of the RX, they could be simply realized by analogue electronic filters.…”

“…Recently, within the COCONUT EU FP7 project [6], we demonstrated a cost-effective 10 Gb/s LR-PON based on a Directly Modulated Laser (DML), where a low-complexity coherent receiver with simple postdetection filtering [7] produces an effect similar to chirp management [8] so as to compensate for fibre dispersion. In this paper, we build on the approach of [7] and extend it to a WDM scenario (4λ's). We chose a 4×10 Gb/s configuration and demonstrate 40 Gb/s downstream (DS) aggregated bit-rate over an optical distribution network (ODN) consisting of 110 km of standard Single Mode Fibre (SMF).…”

Field-Trial of a High-Budget, Filterless, $\lambda$ -to-the-User, UDWDM-PON Enabled by an Innovative Class of Low-Cost Coherent Transceivers

“…The signal processing was realized offline, using a real-time oscilloscope (Real Time Oscilloscope (RTO), 13 GHz analog bandwidth, 40 GSa/s): it emulated 3 parallel processing stages, each having a 3 GHz low-pass filter (for frequency-to-amplitude conversion) and a squaring function: the three processed signals were then added to recover the ASK signal. BER of the received signal was also computed within the RTO by a custom developed routine [33]. This system exploits a heterodyne transceiver whose detailed scheme is depicted in Figure 6.…”

Time–Frequency Packing Applied to Cost-Effective IM/DD Transmission Based on Directly Modulated VCSEL

“…Concerning access networks applications, recent efforts focus on techniques to enhance both the data rate and the fiber reach in case of bandwidth-limited directly-modulated (DM) lasers, still keeping on-off-keying (OOK) modulation, together with wavelength-dependent simplified coherent detection that, however, could hardly be exploited in case of DM-VCSELs due to their phase noise and drift of the emission optical frequency [18].…”