Dispersion compensating fibers for Raman applications

Design and comparative performance evaluation of chirped FBG dispersion compensation with DCF technique for DWDM optical transmission systems

Objectives: This study aims to enhance and optimize a modern communication system for high data rate transmission using Dense Wavelength Division Multiplexing (DWDM). The objectives include employing a 64-channel DWDM system, implementing different data speeds, and utilizing a dispersion compensation method. Methods: To achieve the objectives, we simulate and analyze the effects of Dispersion Compensation Fiber (DCF) in a DWDM system with 64 channels. The system employs Non-Return-to-Zero (NRZ) modulation format at varied bit rates and multiple energy levels. We propose a method for achieving data rates of 10 to 40 Gbps using NRZ modulation and Erbium-Doped Fiber Amplifier (EDFA) over a single-mode fiber transmission distance of 40 to 160 km, along with a dispersion compensation fiber of 8 to 32 km (DCF). The performance of the developed model is evaluated based on Quality Factor, Bit Error Rate (BER), Eye Height, and Threshold. These metrics are measured at two input energy levels from an optical power source, covering a communication capacity ranging from 0.625 Tbps to 2.5 Tbps. Findings: Through the simulations and analyses, we uncover the impact of dispersion and demonstrate the effectiveness of the proposed method in compensating for dispersion effects. Performance analysis of two different input transmitter power levels, -10 dBm is more efficient compared to 0 dBm input transmitter power in terms of bit error rate and quality factor. Novelty: This study presents a novel approach to improving modern communication systems by utilizing DWDM with a dispersion compensation method. The use of a 64-channel DWDM system, combined with the proposed NRZ modulation technique and dispersion compensation fiber, provides an efficient solution for achieving high data rates over long transmission distances while minimizing the effects of dispersion. The findings contribute to the advancement of communication systems for high data rate transmission. Keywords Dispersion effect, Bit Error Rate, Q-factor, Optisystem software, Erbium doped fiber amplifier

Summary form only given. Dispersion-compensating fiber (DCF) devices relying on normal dispersion for the propagating mode are quite long (typically on the order of several kilometers) and therefore exhibit significant insertion loss. We propose and demonstrate Raman gain induced in the DCF as a simple and attractive method for obtaining lossless DCF modules. The Raman efficiency of the DCF is quite high because of the small mode-field diameter of the fiber, which leads to modest pump power requirements. A pump power of only 225 mW provides enough gain to offset the insertion loss of our 15.7-km DCF module with -1400 ps/nm of dispersion. We have also investigated the noise performance and verified penalty-free operation in a 9.953-Gbit/s transmission experiment.

Among the promising advancements towards long-haul transmission is the use of Fiber Bragg Gratings (FBGs) and Dispersion Compensation Fiber (DCF) as the dispersion compensation methods for an optical system. In this work, 8x10 Gbps optical system with channel spacing 100 GHz, 300 Km distance, for three modulation schemes (CSRZ, DPSK and DQPSK) are used to make an optimization in the performance of the optical system. All results are taken in form of Bit Error Rate versus Signal to Noise ration and Quality factor versus Signal power, Optisystem software V.10 is used. The DCF overcomes FBG by 0.375 BER order using RZ-DPSK modulation, while in case of RZ-DQPSK the DCF improvement by 0.2 BER order. In CSRZ modulation, DCF gives additional improvement by 1.3 order where BER values at 9.5 dB SNR.

We have demonstrated essentially complete dispersion compensation for 400-fs pulses over a 10-km fiber link using dispersion compensating fiber and a programmable femtosecond pulse shaper functioning as a spectral phase equalizer. The pulse shaper impresses adjustable quadratic and cubic phases onto the spectrum and removes all the residual dispersion and dispersion slope in the dispersion compensated fiber link. Our work shows that the pulse shaper technique provides a powerful and convenient tool for programmable fiber dispersion compensation over broad optical bandwidth. This allows distortion-free femtosecond pulse transmission over a fiber link in excess of 10 km without requiring the exact trimming of the dispersion-compensating fiber.

This paper has highlighted the simulative performance evaluation of high speed long distance soliton propagation data transmission system based on dispersion control in optical fiber system. The dispersion management for the soliton fiber system is demonstrated based on both symmetrical fiber Bragg grating (FBG) and symmetrical dispersion compensated fiber (DCF) fiber compensation system. The soliton pulse dispersion is measured versus the single mode fiber cable and symmetrical FBG compensation lengths based on the different data rates transmission. Overall system dispersion, overall system data rate transmission, overall optical/electrical system signal per noise ratio, overall system transmission distance and overall system bit error rate are demonstrated clearly against various symmetrical DCF compensation lengths with/without the soliton fiber transmission system. Improvement ratio in both dispersion management and data rate transmission are clarified against symmetrical FBG and DCF compensation techniques and single mode fiber cable length variations. As well as the overall system dispersion and data rate transmission are studied and highlighted in relation to hybrid FBG/DCF compensation techniques and without any dispersion compensation in the presence and absence of soliton fiber transmission system.

We experimentally investigated and demonstrated an ultralow noise hybrid amplifier that combines second-order distributed Raman amplifier (DRA) and first-order lumped Raman amplifier (LRA) in a cascaded approach. This approach allows for the reutilization of pump light from the LRA as the seed light in the second-order DRA, and simultaneous full-band dispersion compensation is realized by using dispersion compensation fiber in the LRA. This approach also supports broadband gain flattening based on the separated DRA and LRA configuration. The transmission application of the proposed amplifier was investigated using a set of 10 external cavity lasers (ECLs) in the C-band and 8 ECLs in the L-band. Ranging from 1531.12 nm to 1595.49 nm across C + L band, the proposed hybrid amplifier gives a maximum on-off gain of 27.2 dB and an average gain of 23.4 dB, with an extremely low effective noise figure (NF) of lower than -2.9 dB. Intensity modulation direct detection (IMDD) signal transmission is carried out at two different data rates across these 18 wavelengths in the C + L band: (1) 56 Gbps/λ PAM-4 signal; (2) 112 Gbps/λ PAM-4 signal. The results show that the error free transmissions are demonstrated over 101.6 km EX2000 fiber using both signals with 7% HD-FEC and 20% SD-FEC, respectively.

The present paper proposes the optimal transmission parameters for non-return-to-zero (NRZ), return-to-zero differential phase shift keying (RZ-DPSK), carrier-suppressed RZ-DPSK (CSRZ-DPSK) and duobinary (DB) modulation formats in 16-channel 10 Gbit/s wavelength division multiplexed passive optical network (WDM-PON) transmission system. The paper investigates influence of laser output power, length of dispersion compensating fiber (DCF) and application of erbium-doped fiber amplifiers (EDFA), as well as impact of optical components configuration on received signal quality. It compares demand of these modulation formats for amplification and dispersion compensation with the increase of transmission distance, determining the optimal conditions for achieving maximal network reach for each of them. It is shown, that DB is the most resistant to chromatic dispersion (CD) and is able to achieve the longest transmission distance (100 km) without dispersion compensation. Whereas RZ-DPSK and CSRZ-DPSK modulation formats demonstrated maximal achievable reach (180 km) using DCF and EDFA.

The Optical OFDM system is considered to be the essential backbone of the next generation of ultra-high-speed networks. A Dispersion effect is considered one of the common limitations in optical OFDMA system especially at very high date rate. When the pulse width reaches less than a few pico-seconds, not only the second-order but even higher-order dispersion must be taken into account. High order dispersion such as a third-order and higher-order dispersion effects are not fully compensated using the traditional dispersion compensating devices such as Dispersion compensating fiber (DCF). Thus the received signals at the receiver end would be distorted dramatically, even if only a small outside effect affects the transmission link. The tunable adaptive equalizer (TAE) system is proposed in this work at the receiver end to recover higher-order dispersion which would not be compensated by DCF fiber. Therefore, the overall system performance based TAE system is improved in terms of (Bit error rate and eyes diagram) which is considered the solution for optical OFDMA next generation optical networks.

Fiber-optic dispersion and its effect on optical transmission system are analyzed. The most commonly used dispersion compensation fiber (DCF) technology is studied in this article. Three schemes (pre-compensation, post-compensation, mix-compensation of dispersion compensation) of dispersion compensation with DCF are proposed. The simulation model of the WDM based on the Optisystem is presented according to the above principle. The simulation results such as Q factor and BER are given and deeply analyzed. It is found that mix- compensation performance is the best. And the input fiber power is taken as 9-10 dB, the corresponding BER performance is better.

A Radio-over-Fiber (RoF) make use of the advantages of wireless communication system and optical networks. It uses optical fiber as a core technology due to the enormous advantages offered by it. Making use of mobility available by wireless communication. Dispersion management and modulation were investigated for two Channel-WDM optical communication systems. Dispersion compensating fibers (DCF) are used to compensate the positive dispersion accumulated over a protracted haul SMF between CS (central Site) and BS (Base Station). The full duplex RoF system is implemented by means of Wavelength Division Multiplexing (WDM) and Optical Add Drop Multiplexer (OADM), where WDM enables transmission of many signals via a single mode fiber for long distance while OADM allows data transmission of both down-link and uplink a by single-mode fiber (SMF). The modulation technique employed by the proposed system is DPSK. which has some advantages over binary PSK, like a low phase error rate and no need to know the absolute phase. The proposed RoF system has been simulated using Opti System 13.0 simulator. The system outcomes like the Q-factor, and BER with and without (DCF) at different fiber length have been used to discuss system performance. It has been observed that the proposed system improves the Q-factor by 6-units and the BER by 24 dB at CS and 57dB at BS respectively.

This paper has deeply simulated the different configurations of pre, post, and symmetric dispersion compensation-based dispersion compensated fiber (DCF), Gaussian optic filter (GOF), and fiber Bragg grating. Output power, signal quality factor, and signal gain are the performance parameters in this study for the complete comparison for the proposed techniques for dispersion compensation. It is observed that FBG has presented the best performance parameters optimization in compared to other compensation techniques for different configurations of compensation. The FBG dispersion compensation technique is the key solution for dispersion compensation in compared with other compensation techniques that are comparatively as in previous section. It is observed that the FBG is the best dispersion compensation technique and change its location, and length, apodization, and chirp functions, to obtain the best performance of FBG and give the best quality factor, output power, and gain, FBG can be employed in different categories such as post compensation, pre compensation, and symmetric compensation with different FBG lengths, apodization, and chirp functions.

With advancement in telecommunication technology spectrally efficient modulation formats are used at high data rates. Long haul network deploy various dispersion compensation mechanisms based on dispersion compensation fiber (DCF). The work presented in this paper explores the suitability of pre, post and symmetrical dispersion compensation techniques at 40Gbps channel in a mixed line rate network. A modified symmetrical dispersion compensation mechanism is proposed and is found to be better than existing dispersion compensation schemes.

We report on the investigation of large energy dissipative soliton resonance (DSR) pulse generation in a simple linear cavity Tm3+-doped fiber laser (TDFL), by using semiconductor saturable absorption mirror as saturable absorber. This DSR TDFL is implemented by utilizing ultra-high numerical aperture 4 (UHNA4) fiber for dispersion compensation. With further dispersion management, the DSR TDFL can generate an average output power of 242 mW with corresponding pulse energy of ~61 nJ. Moreover, the soliton molecules mode-locked operation has also been demonstrated in this TDFL. Our results can provide an easily accessible way to develop large energy TDFLs.

Dispersion compensating fiber (DCF) has seen considerable progress over the last decade and due to its well-controlled dispersion profile, high reliability and passive operation it has ecome the preferred method for compensating chromatic dispersion in today's optical communication systems. Raman amplification in fibers has found increased use in especially long-haul, high-capacity systems, mainly due to its low noise figure and versatile gain bandwidth. In this paper, we describe how Raman amplification can be used in DCF to realize discrete dispersion-compensating amplifiers, the so-called dispersion compensating Raman amplifier (DCRA). The main focus is on system applications and demonstrated results using DCRAs. These application include terminal compensation using DCRAs, hybrid amplifiers where the DCRA can be used to extend the dynamic range of existing erbium-doped fiber amplifiers (EDFAs), as well as hybrid EDFA/DCRAs with ultra wide gain bandwidth.