LUT-Free Carrier Recovery for Intradyne Optical DPSK Receivers in udWDM-PON

Abstract

We present an LUT-free carrier recovery architecture for intradyne optical DPSK receivers that reduces the required DSP hardware resources, power consumption as well as total process clocks, aimed at cost-effective transceivers for access networks applications. The proposed architecture simplifies frequency compensation algorithm to avoid using m th -power operation and LUTs. We prototyped the proposed carrier recovery on a commercial FPGA for real-time evaluation with data at 1.25Gb/s. The optical transmission system is implemented by direct-phase modulation of commercial DFB lasers, 25 km of single-mode fiber, and a coherent receiver with low-cost optical front-end based on 3x3 coupler and three photodiodes providing phase-diversity operation. Results show high performance in realtime, achieving -54 dBm sensitivity at BER = 10 -3 as well as feedforward frequency error correction, high robustness against the fast frequency laser drifts, and high tolerance to optical phase noise in a 6.25GHz spaced ultra-dense WDM grid.

Flexible coherent UDWDM-PON with dynamic user allocation based on limited-tunability lasers

“…When crossing the neighbor channel by using the 'DPC' function, with the switching channel power attenuated 18 dB, the SNR guarantees a BER penalty lower than 1 dB [34]. In fast activation process without attenuating the power of the switching channel, the effective crossing time takes less than 700 ns, producing a burst error of 875 bits at 1.25 Gb/s transmission, which can be assumed by buffering [33].…”

LUT-Free Carrier Recovery for Intradyne Optical DPSK Receivers in udWDM-PON

“…Fig. 3 shows practical implementation of the proposed architecture for CR based on equation (5), with the differential PR (the same as in Fig. 2) followed by Frequency Compensation (FC), where 𝑁𝑁 represents the number of parallel symbols processed by the FPGA, and Control Unit makes the decision rules yielding the 𝑢𝑢 𝑅𝑅 and 𝑢𝑢 𝐼𝐼 with binary values to control multiplexers (MUXs) to pass either the current input or logical NOT of that input.…”

“…We evaluate our proposal in a real-time experiment with a digital coherent Rx implemented on a commercial FPGA, an optical front-end based on low-cost 3x3 coupler, distributed feed-back (DFB) lasers, and direct DPSK modulation at 1.25 Gb/s. The operating principle of the proposed technique and the first real-time experimental results are reported in our preliminary work [5].…”

Investigation of a Flexible Downstream Scheme for Sampling Rate and Bandwidth Reduction in Short Reach Communication Systems

“…The ever-growing bandwidth requirements of end-user applications services have put a lot of pressure on the access network bandwidth. In order to solve the problem, passive optical network (PON), as a cost-effective solution to provide high-speed access, has gained extensive attention and been widely adopted [1]- [6]. By comprehensively weighing various factors, the next generation PON stage 2 (NG-PON2) standardization adopts Time-/wavelength-division multiplexing (TWDM) as the solution [7].…”