Dispersion-shifted fiber polarization scrambler based on faraday effect

Demonstration of an all-fiber polarization scrambler based on the Faraday effect is carried out. The device has been constructed using dispersion-shifted fiber that has a major tolerance to bends than standard single-mode fiber. Results about the fiber Verdet constant when 1550-nm light is launched are presented. The performance of the constructed device is also shown. Main features are insertion losses as low as 0.4 dB and scrambling frequency up to 20 kHz. Although here we emphasize its application to low-frequency heterodyne detection, the scrambler is applicable to other systems that are polarization dependent. In particular, it would be useful to overcome problems originated by polarization dependent gain in erbium-doped fiber amplified systems.Peer ReviewedPostprint (published version

Ultrafast wavelength jumping and wavelength adjustment with low current using monolithically integrated FML for long-reach UDWDM-PON

Ultrafast wavelength jumping at optical network units (ONUs) for an access network with frequency modulated lasers (FMLs) is demonstrated. This FML consists of an intracavity tunable phase section and filtering gain section. It provides a total of 4.2 nm tuning range with fast wavelength jumping (2.2 nm in 1 µs) and fast adjustment (1.3 nm in 1.8 ns), providing a candidate for the fast tuning ONU for coherent ultradense wavelength-division multiplexing passive optical networks (WDM-PONs).Peer ReviewedPostprint (author's final draft

Channel crosstalk in ultra-dense WDM PON using time-switched phase diversity optical homodyne reception

Experimental study of channel crosstalk effects in time-switched phase diversity optical homodyne reception is presented, precisely focused towards ultra-dense wavelength division multiplexed (WDM) passive optical networks (PON). This receiver achieves ultra-low channel spacing and feasible implementation.Peer ReviewedPostprint (published version

Digital phase estimation method based on Karhunen-Loève series expansion for Coherent Phase Diversity Detection

A novel phase estimation method for coherent systems is presented and demonstrated. It outperforms 5.5 times the phase noise and spectral width tolerance respect to the other methods.Peer ReviewedPostprint (published version

A novel methodology for measuring coherent homowavelength crosstalk in an optical signal supervisory system

We present a novel, easy, and cost-effective methodology that allows an optical signal supervisory system the detection, isolation, and measurement of the coherent homowavelength crosstalk within an optical node. It also identifies the degradation origin.Peer ReviewedPostprint (published version

Experimental demonstration of heterodyne phase-locked loop for optical homodyne PSK receivers in PONs

Experimental demonstration of heterodyne optical Phase-Locked Loop (oPLL), using simplest optics, is carried out. For the first time, the effect of loop delay has been experimentally characterized and compared directly to the most significant oPLL configurations. It demonstrates a linewidth tolerance of 6.5 MHz if FEC codes are used.Peer ReviewedPostprint (published version

Cross-connection management specialisation for WDM-OTN's

WDM optical transport networks (WDM-OTN) will use new all-optical nodes that will perform functions in the optical domain, using wavelength as a new network resource. This paper presents a new approach for the optical cross-connect (OXC) routing operation that takes into account a diminished connection capability.Peer ReviewedPostprint (published version

Design of a wavelength control for coherent detection of high order modulation formats

An automatic frequency control design is proposed and demonstrated. It is based on a high-speed optical VCO. An overall design has been performed, based on simulation results. Also, loop delay and phase noise impacts have been evaluated. Frequency discriminator and VCO proposed have been experimentally characterized, showing an agreement with simulation results.Peer ReviewedPostprint (published version

Simple single-laser coherent transceiver based on low-cost D-EML for edge networks

In this work we demonstrate single-laser, D-EML based coherent transceivers which transmit and simultaneously receive optical single sideband modulations through a phase noise cancelling scheme, leading to phase-noise and frequency-detuning clean signals. We use QPSK and 16-QAM modulations over a 500 Mbaud signal, reaching 1 Gbps and 2 Gbps respectively, with sensitivities as low as -53 and -40 dBm with unmodulated local oscillator, respectively, and -35 dBm for QPSK with modulated local oscillator, achieving high sensitivity coherent UD-WDM for analog radio over fiber and mobile fronthaul over passive optical networks.This work was supported in part by the Spanish Ministry of Science and Innovation, Versatile Optical Coherent Network (VERSONET), under Grant RTI2018-097051; and in part by the European Union’s Horizon Europe Research and Innovation Programme under the Marie Sklodowska-Curie Grant, enabling virtualized wireless and optical coexistence (EWOC), under Agreement 101073265. (Corresponding author: Miquel Masanas.)Peer ReviewedPostprint (author's final draft

Wavelength conversion towards Rayleigh backscattering tolerant PONs via four-wave mixing in SOA-based ONUs

Wavelength shifting in PONs with downstream signal remodulation is presented, allowing upstream transmission over trees with 25km feeder and 1:32 split with penalties <2dB, originally Rayleigh backscattering limited. Side-mode suppression is analyzed for hybrid PONs.Peer ReviewedPostprint (published version