Use Of Dispersion Compensating Fiber Research Articles

COMPARING DISPERSION COMPENSATION METHODS FOR 120 GB/S OPTICAL TRANSMISSION: PRE, POST, AND SYMMETRICAL SCHEMES

One of the major factors that limit the performance of an optical fiber communication system isdispersion. In order to get a high transmission range with high data rates, techniques must be in place to compensate for the dispersion caused by fiber nonlinearity. Dispersion Compensating Fiber (DCF) and Fiber Bragg Grating (FBG) are the trending dispersion compensation techniques in optical fiber communication. The use of DCF and FBG as a method of dispersion compensation can notably enhance the overall performance of the system. Broadening is a function of distance as well as the Dispersion parameter (D). The dispersion parameter is given in ps/nm/km and changes from fiber to fiber and also is a function of wavelength. In this paper, we investigate pre-, post-, and symmetrical compensating schemes in three different compensating models: DCF, FBG, and DCF cascaded to FBG. The system performance was evaluated in terms of Q-factor and Bit Error Rate (BER) for one optical channel communication system at 120 Gbps Return to Zero (RZ) signal launched over Single-Mode Fiber (SMF) of 100 km by using OptiSystem 7.0 software.

Enhanced Spectral Amplitude Coding OCDMA System Utilizing a Single Photodiode Detection

In this paper, the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system is investigated utilizing a single photodiode (SPD) detection technique. The proposed system uses enhanced double weight (EDW) codes as signature codes with three simultaneous users to overcome both phase-induced intensity noise (PIIN) and multiple access interference (MAI). In addition, a dispersion compensating fiber (DCF) is used in order to decrease the group velocity dispersion (GVD) caused in the single mode fiber. An erbium-doped fiber amplifier (EDFA) is used to overcome the attenuation. The use of both DCF and EDFA leads to an appreciable enhancement in the system performance. The system performance is evaluated through its bit error rate (BER), Q-factor, and received power. A comparison between the EDW codes and modified double weight (MDW) codes on the SAC-OCDMA system is demonstrated. Simulation is carried out through Optisystem ver. 7. The simulation results show that: (a) using an avalanche photodiode (APD) over PIN photodiode allows data transmission over longer distances; (b) the use of DCF improves the system BER;(c) using MDW codes gives better BER than using EDW codes.

Priority Based Dispersion-Reduced Wavelength Assignment for Optical Networks

Dispersion in optical fiber degrades the quality of signal in optical networks. Although the use of dispersion compensating fiber (DCF) reduces the effects of dispersion, it is expensive and has more propagation loss compared to step-index fiber (SIF). In this paper, we propose a priority based dispersion-reduced wavelength assignment (PDRWA) scheme to reduce overall dispersion in optical network. In this scheme, the connection requests having a same source-destination (s-d) pair are groomed first to avoid intermediate optical-electrical-optical (O/E/O) conversation and then these groomed connection requests with longer lightpath are assigned the wavelengths having lesser dispersion and the wavelengths having a higher dispersion are assigned to the lightpaths with shorter distance. If the connection requests are assigned to the wavelengths using such constraint on dispersion, the overall dispersion in the network can be reduced to a great extent, which will in turn lead to better performance of the network in terms of overall signal quality (Q-factor) without increasing network setup cost. The performance analysis of the proposed scheme using SIF is conducted with different channel speeds (10, 40 and 100 Gbps) in terms of total dispersion and compared the same with the use of DCF. Furthermore, we have studied the overall Q-factor in the network with different channel speeds and considering polarization mode dispersion (PMD) effect using SIF and DCF.

Realization of Combined Chromatic Dispersion Compensation Methods in High Speed WDM Optical Transmission Systems

Chromatic dispersion (CD) has a significant impact on a quality of transmitted optical signal in high-speed fiber optic communication systems with data rates up to 10 Gbit/s, and as a result CD limits the maximum length of transmission distance. In order to operate fiber optic communication system with a sufficiently low bit error ratio (BER) and minimize the performance degradation caused by pulse distortion and broadening, dispersion compensation is needed. In this work using OptSim simulation software we realize an experimental high-speed WDM fiber optic communication system model with a new combined dispersion compensation mechanism where a conventional dispersion-compensating fiber (DCF), fiber Bragg grating (FBG) or optical phase conjugator (OPC) are used together. The best results were obtained by using FBG-OPC dispersion compensation scheme which showed the lowest BER value. Basis of the results we recommend avoiding the use of DCF for CD compensation where it is possible and use FBG instead. Ill. 15, bibl. 9 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.116.10.875

Realization of Combined Chromatic Dispersion Compensation Methods in High Speed WDM Optical Transmission Systems

Chromatic dispersion (CD) has a significant impact on a quality of transmitted optical signal in high-speed fiber optic communication systems with data rates up to 10 Gbit/s, and as a result CD limits the maximum length of transmission distance. In order to operate fiber optic communication system with a sufficiently low bit error ratio (BER) and minimize the performance degradation caused by pulse distortion and broadening, dispersion compensation is needed. In this work using OptSim simulation software we realize an experimental high-speed WDM fiber optic communication system model with a new combined dispersion compensation mechanism where a conventional dispersion-compensating fiber (DCF), fiber Bragg grating (FBG) or optical phase conjugator (OPC) are used together. The best results were obtained by using FBG-OPC dispersion compensation scheme which showed the lowest BER value. Basis of the results we recommend avoiding the use of DCF for CD compensation where it is possible and use FBG instead. Ill. 15, bibl. 9 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.113.7.622

Dispersion equalization of a 10 Gb/s repeatered transmission system using dispersion compensating fibers

We have investigated theoretically and experimentally the transmission performance of a 10 Gb/s repeatered transmission system using dispersion compensating fibers (DCFs), The system configuration that we considered is a 360 km standard (1300 nm zero-dispersion) fiber transmission system with an optical repeater including DCF's located every 120 km (or every 2100 ps/nm dispersion). The transmitter was a DFB-laser externally modulated by a zero-chirp LiNbO/sub 3/ modulator with NRZ (non-return to zero), 2/sup 23/-1 PRBS data. The system performance is evaluated in terms of electrical eye margin in the receiver/regenerator. We present a complete description of the system performance including the nonlinear SPM (self-phase modulation) effect in both standard fibers and DCFs. The results of this investigation clearly demonstrate that the use of DCF's is an extremely effective method to overcome the chromatic dispersion in high-speed transmission systems. The main results of this study are (1) the new "eye position method" which presents the eye margin degradation from both "1" and "0" levels as a function of dispersion values describes the system performance more effectively than the conventional "EOP (eye opening penalty) method", (2) a rule of thumb is that the total dispersion must be slightly undercompensated to include the SPM effect, (3) a very wide range of dispersion compensation values offers acceptable system performance, and (4) the "equal modular compensation" which is desirable from a practical point of view provides sufficiently large eye margin (33.3% for 10/sup -15/ BER after 360 km) although the "customized modular compensation" where the dispersion compensation is tailored to achieve the maximum eye margin without considering the performance at the intermediate repeater locations provides the largest eye margin (48.5% for 10/sup -15/ BER).