1.25–2.5 Gb/s Simple Nyquist Transmitters for Coherent UDWDM-PON with Enhanced Spectral Efficiency

Velasquez, J. Camilo; Tabares, Jeison; Cano, Iván N.; Prat, Josep

doi:10.1080/01468030.2018.1461281

Cited by 3 publications

(3 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results are obtained from direct laser modulation and band limited electronics influencing on the spectral width of the DPSK data. Further DSP at the transmitter for spectral shaping may lower the required channel spacing as low as 3.75 GHz [22].…”

Section: Resultsmentioning

confidence: 99%

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

Ghasemi

Tabares

Polo

et al. 2019

J. Lightwave Technol.

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 99%

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

Ghasemi

Tabares

Polo

et al. 2019

J. Lightwave Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…An important remark is that the Nyquist filtering eliminates the modulation side-lobes, but the filter roll-off has no impact on the main lobe BW, because of the direct phase modulation that relies on NL exponential modulation of the laser chirp, with strong harmonic dynamics [21], [23]. This phenomena can be appreciated in Fig.…”

Section: B Pulse Shapingmentioning

confidence: 94%

“…In a real PON scenario with direct phase modulation, the benefit of Nyquist spectral shaping becomes apparent when maximum 15 dB differential optical path losses are allowed, as specified in [1] for NG-PON2, due to the strong interference of modulation side lobes on weaker adjacent channels. The results reported in [23] indicate 25% reduction in channel spacing for direct phase modulation with Nyquist shaping, allowing that 2.5 Gb/s BPSK users having 15 dB power difference between adjacent channels can be fitted in a 6.25 GHz spaced optical grid.…”

Section: B Pulse Shapingmentioning

confidence: 95%

Coherent Ultra-Dense WDM-PON Enabled by Complexity-Reduced Digital Transceivers

Tabares

Ghasemi

Velasquez

et al. 2020

J. Lightwave Technol.

Self Cite

View full text Add to dashboard Cite

Coherent technologies along with digital signal processing (DSP) have revolutionized the optical communication systems, significantly increasing the capacity of the fiber channel owing to transmission of advanced modulation formats and mitigation of propagation impairments. However, the commercial solutions for high-capacity core networks are too complex and costly, then hardly feasible, for access networks with high terminal density, where cost, power budget and footprint are the main limiting factors. This article analyses the key enabling techniques to implement a complexity-reduced coherent transceiver (CoTRX) by exploiting photonic integration, simplified optical modulation, low-cost DFB lasers, consumer electronics and low-complexity DSP. Bulk optical modulators are replaced by direct amplitudeand-phase modulation of integrated electro-absorption modulated laser (EML) with smaller footprint, generating up to 8-ary modulation formats. Hardware-efficient DSP algorithms for the coherent transmitter and receiver, including pulse-shaping for direct phase modulation, differential detection for optical phase recovery, and digital pre-emphasis with enhanced tolerance to quantization noise, are investigated to face the challenges imposed by low-cost photonic and electronic devices, such as strong phase noise, wavelength drifts, severe bandwidth limitation, and low resolution data converters. Through numerical simulations and real-time experiments, the results indicate that this new class of CoTRX enables effective implementation of wavelength-to-theuser PON with dedicated 1.25 to 20 Gb/s per user, in an ultradense 6.25 to 25 GHz spaced WDM optical grid, with >30 dB loss budget, outperforming the current competing technologies for access networks.

show abstract