Carolina Franciscangelis

Multidimensional optimization of optical spectral shaping for fiber nonlinearities mitigation in high baud-rate systems

We experimentally demonstrate a multidimensional global optical spectral shaping optimization based on genetic algorithm for fiber nonlinearities mitigation in a 56-GBd PDM-QPSK transmission system. The proposed method increased maximum reach by 24%, reducing transmission penalties by up to 1.8 dB.

Real-time distributed fiber microphone based on phase-OTDR

The use of an optical fiber as a real-time distributed microphone is demonstrated employing a phase-OTDR with direct detection. The method comprises a sample-and-hold circuit capable of both tuning the receiver to an arbitrary section of the fiber considered of interest and to recover in real-time the detected acoustic wave. The system allows listening to the sound of a sinusoidal disturbance with variable frequency, music and human voice with ~60 cm of spatial resolution through a 300 m long optical fiber.

WDM transmission of 3×1.12-Tb/s PDM-16QAM superchannels with 6.5-b/s/Hz in a 162.5-GHz flexible-grid using only optical spectral shaping

We demonstrated the transmission of 3×1.12-Tb/s superchannels (5×224-Gb/s PDM-16QAM) in 162.5-GHz flexible-grid, 6.5-b/s/Hz SE, using only optical spectral shaping, over SSMF-EDFA link. A maximum reach of 600-km with 3-ROADM passes was obtained employing nonlinear compensation.

Theoretical and experimental comparison between power and degree of polarization based optical fiber current sensors

This paper presents a theoretical and experimental comparison of two techniques of optical fiber current sensors (OFCS) based on the Faraday Effect: the power and the degree of polarization (DOP) methods. The DOP method is shown to be insensitive to state of polarization (SOP) changes induced by environmental conditions. A maximum variation of 0.4% in the DOP value in the entire range of applied current from 0 to 100 A was measured. It is the first time to our knowledge that this fact was experimentally verified. Also, for the first time known it is reported that zero current response, DOP = 0.996, is in agreement with the theoretical expected value of unitary DOP. Besides, the theoretical and experimental normalized DOP is shown to have a maximum difference of 0.33% in the entire range of applied current. On the other hand, the power method OFCS is greatly affected by SOP changes. In order to be used in a practical application, its complexity must be increased by the use, for example, of polarization maintaining fibers instead of standard fibers used in the DOP method, increasing the cost of the sensor element.

On-field distributed first-order PMD measurement based on pOTDR and optical pulse width sweep.

A method for PMD distributed localization and estimation based on polarization optical time domain reflectometer technique, pOTDR and pulse width sweep is used on-field for the first time. The method consists in launching light pulses with variable widths in an optical fiber under test and then analyzes the Rayleigh backscattered signal spatial power distribution after passing through a polarizer. Both localization and PMD magnitude are function of OTDR pulse width and can be obtained from the ripple analysis, enabling the characterization of the fiber links.

A Simple Method to Localize and Estimate PMD in Optical Fibers using the Polarization Optical Time Domain Reflectometry Technique

We propose and demonstrate experimentally a method for PMD localization and estimation based in the analysis of the ripple of polarization optical time reflectometry trace as a function of temporal pulse width launched signal.

Low latency disturbance detection using distributed optical fiber sensors

Distributed optical fiber sensors based on phase-sensitive optical time domain reflectometry (Φ-OTDR) are feasible options to detect perturbations in kilometric security perimeters or mechanical structures. This technique takes advantage of electromagnetic interference immunity, small dimensions, lightweight, flexibility, and capability. Moreover, this technique can be combined with dedicated hardware architectures, in order to improve its performance and reliability. This work proposes the use of parallel hardware architectures to implement real-time detecting and locating perturbations in a Φ-OTDR distributed optical fiber vibration sensor. Hardware architectures of the iterative moving average filter and the Sobel filter were mapped on field programmable gate arrays, exploring the intrinsic parallelism in order to achieve real-time requirements. A performance comparison between the proposed solutions was addressed in terms of hardware cost, latency and power consumption.

Simultaneous nominal and effective differential group delay in-service monitoring method for optical communications systems

In this paper, we propose an in-service method to simultaneously monitor both nominal and effective values of differential group delay (DGD) in wavelength-division multiplexing (WDM) optical communication systems, in a per channel basis. The method is based on coherent heterodyne detection of the optical signal. We have demonstrated that the technique is capable to recover nominal DGD values from 0 ps to 90 ps while, at same time, to provide the effective DGD parameter, related to the impairment of optical channels. The relationship between the Q factor and effective DGD was also demonstrated, both numerically and experimentally, for distinct nominal values of DGD inserted on the system, by varying the state of polarization (SOP) of the optical signal at the input of the DGD element.

Real-time multiple machines sound listening using a phase-OTDR based distributed microphone

We propose and experimentally demonstrate a spatially tunable phase-OTDR based distributed microphone for listening to the sound of multiple machines. The distributed acoustic sensing capability, allied with the real-time spatial tuning, enables listening to a drill and to a cooling water system pump placed in two different sections along a single optical fiber, one at a time. The recorded acoustic waveform profile of both machines agreed with their operating cycles. Moreover, the sounds generated by both engines are successfully distinguished with the proposed method even when both machines are operating simultaneously.

Improvement of 112/224-Gbps optical coherent transmission systems by pre-filtering optimization

We provided an approach to improve 112-Gb/s RZ-PDM-QPSK and 224-Gb/s RZ-PDM-16QAM systems performance, based on the matched-filtering principle. An optical pre-filtering optimization at the transmitter side was performed, evaluating different filter profiles. A 33-GHz Nyquist-like optical filter was found to be the best solution to improve both 112-Gb/s and 224-Gb/s systems performance. We also performed a back-to-back evaluation in order to obtain the OSNR performance for the optimized systems. Improvements of 0.5 dB and 1 dB in OSNR performance were found for 112-Gb/s RZ-PDM-QPSK and 224-Gb/s RZ-PDM-16QAN, respectively.