Title :
Digital Coherent Receivers for Long-Reach Optical Access Networks
Author :
Lavery, Domanic ; Maher, Robert ; Millar, David S. ; Thomsen, Benn C. ; Bayvel, Polina ; Savory, Seb J.
Author_Institution :
Opt. Networks Group, UCL Electron. & Electr. Eng., London, UK
Abstract :
The relative merits of coherent-enabled optical access network architectures are explored, with a focus on achievable capacity, reach and split ratio. We review the progress in implementing the particular case of the ultra dense wavelength division multiplexed (UDWDM) passive optical network (PON), and discuss some challenges and solutions encountered. The applicability of digital signal processing (DSP) to coherent receivers in PONs is shown through the design and implementation of parallelized, low-complexity application-specific digital filters. In this work, we focus on mitigating the impact of local oscillator laser (LO) relative intensity noise (RIN) on receiver sensitivity, and propose an algorithm which compensates for this impairment. This phenomenon is investigated theoretically and then experimentally by evaluating the sensitivity of a coherent receiver incorporating different tunable light sources; a low-RIN external cavity laser (ECL) and a monolithically integrated digital supermode distributed Bragg reflector (DS-DBR) laser. It is shown that the RIN of the signal laser does not significantly contribute to the degradation of the receiver sensitivity. Finally, a 10 Gbit/s coherent PON is demonstrated using a DS-DBR laser as the LO laser. It is found that a receiver sensitivity of -38.8 dBm is achievable assuming the use of hard-decision forward error correction.
Keywords :
digital filters; optical receivers; passive optical networks; signal processing; wavelength division multiplexing; DS-DBR laser; DSP; ECL; UDWDM PON; coherent-enabled optical access network architectures; digital coherent receivers; digital filters; digital signal processing; digital supermode distributed Bragg reflector; forward error correction; local oscillator laser; long-reach optical access networks; low-RIN external cavity laser; relative intensity noise; ultra dense wavelength division multiplexed passive optical network; Bandwidth; Laser noise; Optical network units; Optical receivers; Passive optical networks; Semiconductor lasers; Optical access; digital signal processing (DSP); passive optical network (PON); ultra dense (UD); wavelength division multiplexing (WDM);
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2012.2224847