Coherent ONU based on 850 µm-long cavity-RSOA for next-generation ultra-dense access network

In this Letter, an efficient bidirectional differential phase-shift keying (DPSK)-DPSK transmission for a ultradense wavelength division-multiplexed passive optical network is proposed. A single distributed feedback laser at the optical network unit (ONU) is used both as the local laser for downlink coherent detection and the optical carrier for uplink. Phase-shift keying is generated using a low-cost reflective semiconductor optical amplifier (RSOA) at the ONU. The RSOA chip has the bandwidth of 4.7 GHz at the maximum input power and bias current. For uplink transmission, the sensitivity of the RSOA chip reaches -48.2 dBm at the level of bit error rate = 10(-3) for back-to-back, and the penalty for 50 km transmission is less than 1 dB when using polarization diversity.Peer ReviewedPostprint (published version

First demonstration and field trial on multi-user UDWDM-PON full duplex PSK-PSK with single monolithic integrated dual-output-DFB-SOA based ONUs

© 2016 [2016 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.We demonstrate a monolithically integrated dual-output DFB-SOA, and conduct the field trial on a multi-user bidirectional coherent ultradense wavelength division multiplexing-passive optical network (UDWDM-PON). To the best of our knowledge, this is the first achievement of simplified single integrated laser-based neighboring coherent optical network units (ONUs) with a 12.5 GHz channel spaced ultra-dense access network, including both downstream and upstream, taking the benefits of low footprint and low-temperature dependence.Peer ReviewedPostprint (author's final draft

15-dB differential link-loss UDWDM-PON with direct beat phase modulated DFBs

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.IEEE A 15 dB differential link-loss ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) with two optical network units (ONU) spectrally spaced 6.25 GHz is experimentally implemented and tested. The ONU transmitters consist of direct phase modulated distributed feedback lasers (DFB) through a digital beat signal, whose amplitude and duty cycle are optimized for maximum phase variations, avoiding the need for an analogue equalizer. We achieved receiver sensitivities of -53 dBm, -50.5 dBm, and -45 dBm for bit rates of 1.25 Gb/s, 2.5 Gb/s, and 5 Gb/s respectively at BER = 4·10 -3 with an intradyne coherent receiver.Peer ReviewedPostprint (author's final draft

Field-Trial of a high-budget, filterless, lambda-to-the-user, UDWDM-PON enabled by an innovative class of low-cost coherent transceivers

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.We experimentally demonstrate an innovative ultradense wavelength division multiplexing (UDWDM) passive optical networks (PON) that implements the full ¿-to-the-user concept in a filterless distribution network. Key element of the proposed system is a novel class of coherent transceivers, purposely developed with a nonconventional technical approach. Indeed, they are designed and realized to avoid D/A-A/D converter stages and digital signal processing in favor of simple analog processing so that they match system, cost, and power consumption requirements of the access networks without sacrificing the overall performance. These coherent transceivers target different use case scenarios (residential, business, fixed, wireless) still keeping perfect compatibility and co-existence with legacy infrastructures installed to support gray, time division multiplexed PON systems. Moreover, the availability of coherent transceivers of different cost/performance ratios allows for deployments of different quality service grades. In this paper, we report the successful field trial of the proposed systems in a testbed where 14 UDWDM channels (and one legacy E-PON system) are transmitted simultaneously in a dark-fiber network deployed in the city of Pisa (Italy), delivering real-time and/or test traffic. The trial demonstrated filterless operations (each remote node selects individually its own UDWDM channel on a fine 6.25-GHz grid), real-time GbE transmissions (by using either fully analog or light digital signal processing), multirate transmission (1.25 and 10 Gb/s), high optical distribution network loss (18-40 dB) as well as a bidirectional channel monitoring system.Peer ReviewedPostprint (author's final draft

7.5 Gb/s direct DFB phase modulation with 8-DPSK for 6.25 GHz spaced coherent UDWDM-PONs

We demonstrate an 8-DPSK directly phase-modulated DFB with intradyne detection in a 50 km, 6.25 GHz channel spaced UDWDM-PON. A bit rate of 7.5 Gb/s is achieved with Rx sensitivity of -31 dBm at BER=10-3.Peer ReviewedPostprint (published version

7.5 Gb/s direct DFB phase modulation with 8-DPSK for 6.25 GHz spaced coherent UDWDM-PONs

We demonstrate an 8-DPSK directly phase-modulated DFB with intradyne detection in a 50 km, 6.25 GHz channel spaced UDWDM-PON. A bit rate of 7.5 Gb/s is achieved with Rx sensitivity of -31 dBm at BER=10-3.Peer Reviewe

Multilevel direct DFB phase modulation in 6.25 GHz spectrally spaced UDWDM PONs

Direct phase modulation of DFB is demonstrated with DPSK, DQPSK and Duobinary modulation formats and detected with an intradyne receiver based on a 120-degree hybrid. The system is tested in a 50 km fibre link with 6.25 GHz channel spacing among users in a UDWDM-PON. By using higher modulation formats, the spectral efficiency can be increased in a single carrier system without spectral shaping while achieving an Rx sensitivity of -40 dBm at BER = 10-3for 5 Gb/s in a 2 GHz bandwidth limited DFB.Peer ReviewedPostprint (published version

Coherent ONU based on 850 µm-long cavity-RSOA for next-generation ultra-dense access network

In this Letter, an efficient bidirectional differential phase-shift keying (DPSK)-DPSK transmission for a ultradense wavelength division-multiplexed passive optical network is proposed. A single distributed feedback laser at the optical network unit (ONU) is used both as the local laser for downlink coherent detection and the optical carrier for uplink. Phase-shift keying is generated using a low-cost reflective semiconductor optical amplifier (RSOA) at the ONU. The RSOA chip has the bandwidth of 4.7 GHz at the maximum input power and bias current. For uplink transmission, the sensitivity of the RSOA chip reaches -48.2 dBm at the level of bit error rate = 10(-3) for back-to-back, and the penalty for 50 km transmission is less than 1 dB when using polarization diversity.Peer Reviewe

1.25–2.5 Gb/s simple nyquist transmitters for coherent UDWDM-PON with enhanced spectral efficiency

We present a coherent ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) with enhanced spectral efficiency. The benefit of using Gaussian or Nyquist pulse-shaping filters at the transmitter is evaluated through numerical simulations and experiments. The transmitters consist of directly phase modulated distributed feedback (DFB) lasers through beat signals whose duty-cycle and amplitude are digitally adjusted. The results show that transmitting a Nyquist-shaped signal achieves a 25% spectral saving allowing to place 2.5 Gb/s/user data in 6.25 GHz channels. Furthermore, the proposed transmitter tolerates differential link-losses of 15 dB at Rx sensitivity of ¿44 dBm at BER=10¿3 with intradyne detection.Peer Reviewe

Multilevel direct DFB phase modulation in 6.25 GHz spectrally spaced UDWDM PONs

Direct phase modulation of DFB is demonstrated with DPSK, DQPSK and Duobinary modulation formats and detected with an intradyne receiver based on a 120-degree hybrid. The system is tested in a 50 km fibre link with 6.25 GHz channel spacing among users in a UDWDM-PON. By using higher modulation formats, the spectral efficiency can be increased in a single carrier system without spectral shaping while achieving an Rx sensitivity of -40 dBm at BER = 10-3for 5 Gb/s in a 2 GHz bandwidth limited DFB.Peer Reviewe