J.L. Pinto

Analysis of the gain and noise characteristics of fibre Brillouin amplifiers

A theoretical analysis is performed of the transfer characteristics, gain, amplified spontaneous emission noise, on/off ratio and nonlinear phase shift of a fibre Brillouin amplifier, taking into account a possible signal detuning from the line centre and the nonlinear pump power depletion effect. Among other features, it is shown that the amplified spontaneous emission noise is reduced at higher signal levels and that detuning the signal reduces the amplifier gain in the linear regime and increases the spontaneous noise power in the saturation regime. As a consequence, the on/off ratio is significantly degraded by such an effect.

Optical Sensors Based on Fiber Bragg Gratings for Structural Health Monitoring

In this work we review the structural health monitoring techniques based on fiber Bragg gratings. The working principle of the fiber Bragg gratings sensors and the most common techniques to inscribe and interrogate these sensors are described. Several implemented examples are also presented, like the deformation monitoring of one historical building with reduced visual impact, the unidirectional acceleration measurements in a metallic bridge structure and the bidirectional acceleration monitoring in a 50 m mobile telecom tower. Finally, the implementation of an automated remote structural health monitoring system design to operate with optical sensors in a highway bridge is described.

New technique for implementing multiwavelength orthogonal codes for OCDMA using fiber Bragg gratings written in high birefringence fibers

In the recent past, we have seen evolution of many new classes of multiwavelength optical orthogonal codes (MWOOCs) for optical code division multiple access (OCDMA). One important characteristic of these codes is that each set follows a cyclic (modulo-m) generation scheme. In this article, a new concept of polarization-accompanied MWOOCs, based on this scheme, and its implementation is proposed. The method is based on HiBi FBG in opposition to the normal FBG in the traditional implementation.

Bit error rate assessment in DWDM transparent networks using optical performance monitor based in asynchronous sampling

We have implemented a model that takes into account the effects of chromatic dispersion, amplified spontaneous emission noise, non-linear effects and intersymbol interference (ISI). The suggested approach applied to asynchronously sampled amplitude histograms, allow the assessment of the signals BER.

Self-pumped wide range wavelength converter

A new broadband orthogonal pump (BOP) four wave mixing (FWM) wavelength conversion scheme was demonstrated. The implemented set up shown conversion efficiencies higher than -20 dB and with less than 3 dB variation, for different conversion wavelengths. It is also more stable and cost effective when comparing to other BOP FWM wavelength conversion techniques, due to the reduction of the number of devices needed. The tunability of the HiBi fibre ring cavity Bragg grating structure (FBGS) along with the bit-error rate measurements for this wavelength converter is under investigation and will be reported.

Performance analysis of wavelength conversion based on cross-gain modulation in reflective semiconductor optical amplifiers

This paper reports an experimental study of wavelength conversion dynamics using cross-gain modulation in reflective semiconductor optical amplifiers. The effect of pump and probe powers on the operating performance in terms of signal-to-noise-ratio was experimentally investigated. We realise wavelength conversion over 30 nm at 2.48832 Gb/s with reduced SNR degradation.

Optical fiber bending limits for optical fiber infraestructures

In this work the high power propagation in tight bent fibers was studied. The signal losses and the temperature increase have been experimental measured for single mode optical fibers (SMF) as function of the bending diameter. These results were used to propose an approach to limit the bending diameter, as a function of the injected power, in order to maintain the operational condition bellow the safety limit.

Effect of temperature on the single mode fibers chromatic dispersion

We investigate the effect of temperature on optical fiber chromatic dispersion and chromatic dispersion slope, since these parameters affect dispersion compensation at high bit rates. We derive an expression for the chromatic dispersion slope variation with temperature as a function of the zero dispersion wavelength and chromatic dispersion slope at the zero dispersion wavelength. We also verify that this last term has a high contribution to the total chromatic dispersion variation, and can not be ignored. We show that the model of Ghosh et al for the silica refractive index temperature dependence can be used to describe the variation of the dispersion slope within the temperature interval between -40/spl deg/C and 60/spl deg/C. Through numerical simulation we verify that the effect of temperature cannot be ignored in the design of dispersion compensation devices for high bitrate systems (40 Gbit/s).

Multi-wavelength conversion based on a semiconductor optical amplifier self pumped converter

A multi-wavelength conversion technique is studied and characterized. This conversion is based on a beam orthogonal pumping scheme and four wave mixing self pumped device. The converter is characterized for single and multiple wavelength conversion in terms of efficiency. Its possibilities and drawbacks are identified and discussed.

Wide tuning range self-generated orthogonal pumps source based on a reflective semiconductor optical amplifier

In this paper, we present a new architecture for a source of two self-generated orthogonal pumps with wide tuning range, based on a reflective semiconductor optical amplifier (RSOA) and a fiber Bragg grating structure (FBGS) written in a high-birefringence fiber (HiBi). The source is widely tunable, depending on the HiBi FBGS configuration. The implemented setup also has a very simple structure and is highly cost effective due to the reduced number of devices needed.