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Broadband Access Networks (FTTH)
A broadband access network offers various high-speed services to the end-user such as internet, multimedia, tele-medicine and distant learning. Fiber to the home (FTTH) is an optical access network architecture that uses optical fibers to replace all or part of the metallic cables to the end-user. Using OptiSystem we can explore the performance of different architectures for FTTH networks. In this application note, we explain an optical code-division multiple access (OCDMA) structure using three users.....read more
Dense Wavelength Division Multiplexing (DWDM) is a technology that allows multiple information streams to be transmitted simultaneously over a single fiber. This provides a cost effective method to increase the capacity of the existing networks without the need to add additional fiber. This application note explains capabilities of the OptiSystem software to explore different design structures (e.g. modulation format, linear and nonlinear impairment compensation) to optimize the performance of these networks for access and long-haul application....read more
Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission technique where a data stream is carried with many lower-rate subcarrier tones. In optical communication systems, OFDM has received increased attention as a means to overcome various limitations of optical transmission systems such as modal dispersion, relative intensity noise, chromatic dispersion, polarization mode dispersion and self-phase modulation. Coherent Optical OFDM (CO-OFDM) combines the advantages of ‘coherent detection’ and ‘OFDM modulation’ and possesses many merits that are critical for future high-speed fiber transmission systems...read more
100 Gbps DP-QPSK System with Digital Signal Processing
The combination of polarization-multiplexing and quadrature phase-shift-keying (PM-QPSK or DP-QPSK) is emerging as one the most promising solutions to reach bit rates of 100 Gbps and higher. At the receiver end, the use of digital signal processing (DSP) results in significant deployment improvement over the traditional implementation.
This example demonstrates a practical design example of a 100 Gbps DP-QPSK transmission system using coherent detection with digital signal processing for distortion compensation...read more
OCDMA Design
Optical Code-Division Multiple-Access (OCDMA) system simulation is crucial for optical engineers designing networks that require high levels of privacy and security. This Application Note describes how OptiSystem simulates such a network.
Analysis and Simulation on Spectral Phase-Encoded OCDMA System (subscription required)
Abstract
This paper analyzes the temporal behavior of pseudo-random code and the effects on a spectral phase-encoded time-spreading OCDMA System. A spectral phase-encoded time-spreading optical code division multiple access system designed by Optiwave's Optisystem was demonstrated. The system's performance was simulated under the different pseudo-random phase codes. The OCDMA system's performance would be better if the phase codes have equal amount of 1 and -1 and improved by increasing phase code length. The system performance is evaluated by the Bit Error Rates (BER).
Characterization of the chirp in semiconductor laser under modulation (subscription required)
Abstract
In this paper we present, shortly, a study of the chirp induced in direct modulated DFB laser. Our description of the chirp is based, first on analytical resolution of the rate equations, and second on a simulation of a heterodyne system with the Optisystem software. This study enables us to visualize the chirp of a DFB laser in the RF field and to characterize it according to the parameters of the modulation of the injection current i(t). We show by using the powerful Volterra series theory that the linear sweep of the laser optical frequency can be obtained by a triangular modulation of the injection current.
Design and simulation of a novel phase-encoded OCDMA system
Abstract
The security of optical code division multi-access (OCDMA) system was analyzed, and the results indicate the hidden trouble of security. A scheme of multi-codes to be transmitted single-user information has been proposed, and single-user eavesdropping model has been simulated. The soft platform of system simulation was built by optisystem and MATLAB. The simulation analysis of the system has been accomplished on the soft platform. The brute-force searching and a code interception have been studied. The simulation results have shown that this system has better security.
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