The power restrictions limit the communication range of UWB devices to just a few meters, which produce UWB wireless networks operating in stand-alone mode. With the purpose of increasing the coverage area and achieving seamless communications between stand-alone networks UWBoF technology has been proposed. However, the deployment of fiber connecting stand-alone UWB networks is not always feasible. We propose and implement a UWB over free space optic (FSO) horizontal link. Initial results presenting the effects of the optical wireless channel over the UWB signal PSD are demonstrated. These results are analyzed and implementation recommendations are provided based on them.
In this paper, we propose to demonstrate a long haul and high speed network based on a 2 band Orthogonal
Frequency Division Multiplexing (OFDM) signal and a Carrier Suppression (CS) Non Return to Zero (NRZ)
Differential QPSK non-coherent modulation format. We considered 112 Gbit/s per channel bit rate and multiplexed
32 channels following the 100 GHz WDM ITU grid. We demonstrate a transmission over more than 3000 km with a
BER bellow 10-3.
In this paper, we describe and investigate a new UV photo-writing setup using Travelling Interference Fringe (TIF)
technique for Fiber Bragg Grating (FBG) realization. A continuously moving fringe pattern is generated using two
electro-optical UV modulators and is synchronized with the fiber moving speed. FBG parameters such as chirp, phase
shift and apodization profile can be controlled with high precision. This method is used to realize repeatable, flexible and
complex profile spectral phase OCDMA encoders/decoders. Experimental realization results in good agreement with
numerical simulations are presented and discussed. The obtained encoders/decoders are tested within a system setup
using a supercontinuum optical source.
This paper presents the Direct Sequence Optical Code Division Multiple Access (DS-OCDMA) system using two
configurations of the optical source. To encode/decode transmitted data, we used Superstructured Fiber Bragg Grating
(S-FBG) as encoders/decoders. We consider three unipolar family codes which are the Prime Sequence (PS), Quadratic
Congruence (QC) and the Extended Quadratic Codes (EQC) codes. In order to evaluate the performances of our system
in term of Bit Error Rate (BER), we implement the Importance Sampling (IS) technique, which is a variant of the wellknown
Monte-Carlo (MC) method. Our simulation results depict that EQC codes outperform QC and PS codes for the
DS-OCDMA system using either coherent or incoherent source. We show also that using EQC codes with increasing the
optical bandwidth and maintaining the electrical filter leads to improve the performance of incoherent system.
In this paper, we compare the performances of a coherent versus incoherent Direct Sequence Optical Code Division
Multiple Access (DS-OCDMA) system. Superstructured Fiber Bragg Grating (S-FBG) encoders/decoders are used to
implement unipolar codes such as Prime Sequence (PS) and Extended Quadratic Codes (EQC) codes. We implement the
Importance Sampling (IS) technique, which is a variant of the well-known Monte-Carlo (MC) method, to evaluate the
Bit Error Rate (BER) performances of the system. Our simulation results depict that coherent system outperforms the
incoherent one. The last system can be used but a BER floor is demonstrated due to the beat noise of the incoherent
source. We show that increasing bit rate leads to a deterioration of the BER behavior and requiring an increase of the
optical bandwidth of the signal.
In this paper, we interest on the synthesis of spectral phase OCDMA encoders/decoders based on step chirped Fiber
Bragg Gratings to enhance their spectral and temporal efficiency. In this process, we use a real-coded Genetic Algorithm
as a synthesis technique. The encoders/decoders are formed by step chirped fiber Bragg gratings with π phase shifts
giving rise to bipolar code signatures. In fact, the device structure results from the concatenation of fiber Bragg gratings
with different nominal periods and π phase shifts inserted between the gratings to implement the code behavior. Ecole Polytechnique de Montreal
A new architecture of multiple private networks independent of optical line terminal (OLT) over Ethernet passive optical
network (EPON) using ring topology is proposed. This architecture integrates the multiple private networks (PNs) with
downstream/upstream EPON. Self determining private communications between optical network units (ONUs) are
established using code-drop units. The use of optical code division multiple access (OCDMA) technique results in secure
and reconfigurable PNs in the ring. Each ONU is assigned an appropriate codeword for private network communication
and also the standard equipments for the up/downstream standard EPON communication. As an example, by using
quadratic congruent (QC) codes with (p=5) leads to four optical private networks in the ring. To demonstrate the
integration feasibility of multiple 622 Mb/s PNs over 1.25 Gb/s EPON using QC code-drop units, we analyze the
network architecture by evaluating power budget, network dimensioning and BER performances.
In this paper, we propose a numerical tool for the synthesis of DS-OCDMA Encoders/Decoders based on Fiber Bragg Gratings. The techniques of synthesizing FBG are described. In particular, we point out the layer peeling method as inverse scattering approach and a genetic algorithm approach to design DS-OCDMA Encoders/Decoders. Finally, we compare the results of the two synthesizing methods.
This paper presents the experimental demonstration of a 1 Gbps Direct Sequence Optical Code Division Multiple Access (DS-OCDMA) system using pulsed coherent source. Encoding and decoding using Prime Sequence codes are achieved by Sampled Fiber Bragg Gratings (S-FBGs). The encoders/decoders have been designed with OptiGrating software and
realized with Phase Mask Process. BER measurements have been performed in the asynchronous configuration when an interferer is delayed from the desired signal. A 2 dB penalty due to Multiple Access Interference effect (MAI) has been observed in the synchronous case. S-FBG technological limitations and optical interferences due to the source coherence time have been observed and will be discussed.
In this paper, we present an original detection method using three fast detectors to monitor the spatio-temporal dynamics of a bimode CO2 laser with saturable absorber. We observe that the time dependent components of the modal amplitudes increase as the frequency degeneracy lift between the TEM01 and TEM10 modes is reduced. Just before locking the system undergoes a period-doubling cascade leading to chaos. We record the temporal evolution of the modal amplitudes and the optical phase difference between the two modes in the specific regimes within the period-doubling cascade. Numerical simulations are in good agreement with the experiments, in particular they confirm the existence of the period-doubling cascade.