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Access infrastructure combining fiber optic and wireless technologies can provide the necessary broadband access required by convergence of wireless and wired networks. Optical millimetter-wave generation using up-conversion is considered as a cost-effective solution in radio over fiber systems. In this paper we discuss and compare the robustness against dispersion of three millimetter-wave generation...
In this paper, we discuss the operation principles, challenges and application areas of optical frequency domain reflectometry technique. A review of OFDR systems is given considering both Incoherent-OFDR and Coherent-OFDR groups. Results obtained by different research groups are compared in terms of performance characteristics, and future perspectives. Recent progresses obtained within our laboratory...
We present a novel constraint-based routing (CBR) algorithm, which accurately estimates linear and nonlinear physical-layer impairments of 43 and 107 Gb/s channels with duobinary and DQPSK modulation formats by combining fast analytical models for assessing the linear transmission impairments with a split-step Fourier approach optimized for computational speed to estimate the nonlinear intra-channel...
This paper discusses hybrid fiber optic access network architectures combining baseband wireline and mm-wave channels. We focus on mm-wave radio over fiber (RoF) optical access network architectures which combine radio subcarrier multiplexing techniques to improve system efficiency with fiber dispersion mitigation provided by optical single sideband modulation techniques. Besides discussing the network...
We proposed and demonstrated a novel time domain spectral phase encoding/decoding scheme by time domain stretching and high speed phase modulating short optical pulses. 16 chips, 40 GHz/chip optical codes have been generated and recognized successfully using long chirped fibre Bragg grating (LCFBG) as dispersive components, respectively. Transmission experiments have been carried out successfully...
Optical communication systems depend heavily on the performance of the light emitter, usually a distributed feedback (DFB) laser. This paper presents optimised corrugation-pitch-modulated (CPM) distributed-coupling-coefficient (DCC) DFB laser structures specially designed for single longitudinal mode operation. The optimisation process is described and divided into two stages: near and above threshold...
Vertical Cavity Surface Emitting Lasers (VCSELs) have many advantages but their multi-mode transverse mode behaviour introduces problems for applications where output mode shape is important such as injection into fibre. Several groups world-wide have been investigating introducing photonic-crystal-hole patterns into the top-DBR to control the transverse modes. This has been observed to enhance the...
The polarization anisotropy of microstructure fibre may be introduced especially to provide more possibilities to control the supercontinuum production. Thus polarization degree of freedom should be incorporated to the numerical model. In this paper we analyze numerically the supercontinuum generation in the microstructure fibres with periodically modulated holes ellipticity. Femtosecond pulse propagation...
A new method of phase modulation to amplitude modulation conversion (PM/AM conversion) based on an integrating capabilities of uniform fiber Bragg grating (FBG) was proposed and its use in a wavelength converter was experimentally demonstrated. The wavelength converter was based on cross-phase modulation XPM in 500 m of highly nonlinear fiber. The pulsewidth of input pulses was 1.5 ps and the pulsewidth...
Result of numerical simulations are presented on transmission limits for different modulation formats at 100 Gb/s caused by non-linear effect and chromatic dispersion in standard and non-zero dispersion shifted single mode fibres. Different modulations formats are simulated and their properties compared.
The MQW GaInAsSb/AlGaAsSb lasers are monomodal throughout almost the whole temperature range of its operation, and they can be tuned in a wide spectral range. With the combination of the Fourier transform spectrometer and the diode lasers as sources of coherent radiation, we compared the spectra measured with a FTIR spectrometer in its absorption arrangement using a 50 W halogen lamp, with a laser...
The purpose of this work is to describe and demonstrate a new concept of a hybrid communication system, which consists of applying electrical CDMA to each data channel, on a system using optical WDM. Each user has a unique orthogonal CDMA code and modulates an electrical carrier (e.g. QPSK) prior to the data is used to directly modulate an optical carrier, using a laser. Therefore, it is possible...
Optical networks are fairly static and operate within well-defined specifications. The addition of new nodes or the upgrade of existing links demands an enormous expenditure. A cost-effective implementation of future optical networks should accommodate old static networks, as well as new highly-efficient networks. It also should be intelligent, self-managed, monitored and dynamically-reconfigurable...
Many simulative approaches have been proposed to investigate semiconductor optical amplifier (SOA) behaviour, in order to model its performance when used in several scenarios. Most of the applications of SOAs are based on the propagation of maximum two signals within the active medium, thus, higher order phenomena due to beating of more than two signals are not always correctly predicted by usual...
We propose a bidirectional reflective semiconductor optical amplifier (RSOA) based wavelength-division-multiplexing passive optical network (WDM-PON) utilizing a differential phase shift keying (DPSK) signal for down-link and an on-off keying (OOK) signal re-modulated for up-link with high extinction-ratio in both directions. A 20 km range colorless WDM-PON without dispersion compensation was demonstrated...
In this work we present a possible ldquoway-to-gordquo for all-optical processing, shortening the distance between typical all-optical scenarios and real standardized optical networks. This is based on the usage of dual-polarization quadrature phase-shift keying (DP-DQPSK) for transmission with subsequent conversion to amplitude shift-keying for optical processing in metro/access network scenarios.
Within this contribution the impact of phase ripples and amplitude filtering induced by fiber Bragg gratings (FBGs) for in-line dispersion compensation in optical long-haul wavelength division multiplex (WDM) transmission systems is investigated. The goal is to evaluate the possibilities and limitations of employing FBGs instead of dispersion compensating fiber (DCF) in modern communication systems...
Some of the most promising transmitter linearization techniques for high performance radio over fiber systems are reviewed and compared through simulation tests. Comparison is focused on Mach-Zehnder modulator (MZM) operated at low bias; MZM conventionally biased at quadrature, driven with low modulation depth and cascaded with a notch optical filter; optical single sideband and double sideband plus...
All-optical modulation over ultra-wide wavelength range using intersubband transition (ISBT) quantum well will be presented. This is based on cross-phase modulation (XPM) through the intersubband transition in an InGaAs/AlAsSb coupled quantum well using a linearly polarized pump wave. Optical millimeter wave at 76 GHz has been generated over a wavelength range of 1330 - 1620 nm using sinusoidal-intensity...
An optical model of a surface-normal electro-absorption (EA) modulator consisting of multiple-quantum wells (MQWs) embedded in an asymmetric Fabry-Perot (FP) cavity formed by high-reflective back DBR and moderate-reflective top DBR separated from MQWs at both sides by buffer layers is analysed numerically by the method of single expression (MSE). Reflectance of the modulator versus normalised thickness...
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