Comparative Analysis of DCF based Dispersion Compensation Techniques in Optical Fiber Communication Link using Different Input Transmitter Conditions at 10 Gbps

In this paper, Dispersion Compensating Fiber (DCF) based various dispersion compensating techniques (pre, post and symmetrical) with different modulation format like Non Return to Zero(NRZ), Return to Zero(RZ), Carrier Suppressed Return to Zero(CSRZ) and Duo Binary(DB) along with PN, FCC and Walsh code input sequences are implemented. Simulation and analysis of these implemented techniques were done at 10 Gbps bit rate and input laser power ranging from 1 mW to 10 mW at transmission distance of 240 km using BER Analyzer in Optisystem 17.0 software. Comparison between different techniques was done in terms of Q factor and BER versus input CW laser power for different modulations and input sequences. From the analysis, it is concluded that when Walsh code as user defined input sequence are used for all the implementation, it gives higher value of Q factor and lower value of Bit Error Rate as compared to PN and FCC codes for most of the input CW laser power

100 Gbps/λ PON downstream O- And C-band alternatives using direct-detection and linear-impairment equalization [Invited]

The future-generation passive optical network (PON) physical layer, targeting 100 Gbps/wavelength, will have to deal with severe optoelectronics bandwidth and chromatic dispersion limitations. In this paper, largely extending our Optical Fiber Communication Conference (OFC) 2020 invited paper, we review 100 Gbps/wavelength PON downstream alternatives over standard single-mode fiber in the O- and C-bands, analyzing three modulation formats (PAM-4, partial-response PAM-4, and PAM-8), two types of direct-detection receivers (APD- and SOA $+$+ PIN-based), and three digital reception strategies (unequalized, feed-forward equalized, and decision-feedback equalized). We evaluate by means of simulations the performance of these alternatives under different optoelectronics bandwidth and dispersion scenarios, identifying O-band feasible solutions able to reach 20 km of fiber and an optical path loss of at least 29 dB over a wide wavelength range of operation. Finally, we compare two digitally precompensated modulation schemes that are highly tolerant of chromatic dispersion, showing a possible extension to C-band operation, preserving direct-detection and linear-impairment equalization at the optical network unit side

Design and Analysis of Binary Driven Coherent M-ary Qam Transmitter for Next Generation Optical Networks

This work presents a design for a binary driven optical square M-ary quadrature amplitude modulation (QAM) transmitter for high speed optical networks. The transmitter applies tandem quadrature phase shift keying (QPSK) modulators to eliminate the need for linear broadband amplifiers and high-resolution digital to analog converters (DACs), which are both required by conventional transmitters. The transmitter design could be scaled to any order of square M-ary QAM by simply adding more QPSK modulators in tandem. It also provides a Gray coded symbol constellation, insuring the lowest bit error rate possible during symbol recovery. We also provide the design for the coupling ratios of the optical couplers that take into account the insertion loss of the optical components, in order to generate a proper 16-QAM and 64-QAM symbol constellation with equally-spaced symbols. Additionally, we analyze the impact of coupling ratio errors as well as phase errors on the bit error rate (BER) performance and constellation diagrams. The performance is tested using the OptiSystem simulation at 50 Gbaud and under presence of additive white Gaussian noise (AWGN), which demonstrated high quality symbol constellation and a BER performance similar to theoretical expectations. For 16-QAM, a BER better than 10-4 and power penalty of about 2 dB are achieved for coupling ratio errors less than 10 %, or phase errors within ±7 degrees. The 64-QAM transmitter, on the other hand, demonstrated a BER better than 10-4 and power penalty of about 1 dB for coupling ratio errors less than 4%, or phase errors within ±2 degrees. Adviser: Lim Nguye

DCF with FBG for Dispersion Compensation in Optical Fiber Link at Various Bit Rates using Duobinary Modulation Format

Dispersion is one of the very important parameters that effect on the performance of optical fiber communication systems. It causes pulse broadening, limiting of transmission distance and the number of channels on optical fiber link and low Bit rate. Dispersion compensation fiber (DCF) based on Fiber Bragg Grating (FBG) is widespread used in the dispersion compensation scheme. In this work, the proposed dispersion compensation fiber is included (pre – post–symmetrical) schemes with Fiber Bragg Grating and duo-binary modulation format. These are at various bit rates (10 Gbit/s, 20 Gbit/s, 30 Gbit/s and 40 Gbit/s) and different input laser power from (0 dBm to 10 dBm) for 200 Km distance. Optisystem software version 10 is used to design simulation model. Q- factor and BER are two parameters which used to evaluate the performance analysis of the system, we concluded that, the symmetrical compensation techniques is better than others compensation schemes when the Q factor is 52.977 and bit rate is equal 0, these at 10 Gbit/s and 10 dBm transmitted power

Comparative performance study in multiplexed RZDPSK for SMF's with FBG

The Fiber Bragg gratings have emerged as important components in several of light wave applications in the FBG becoming a ubiquitous and necessary element in equipment located throughout the network from the central office to the home. This paper explores comparative performance study with and without using FBG as an external dispersion compensator for sixteen channel return to zero differential phase shift keying modulation operating at 45Gbps per channel with channel spacing of 0.15nm. Simulations are done with various single mode fibers with and without external FBG.Better performance (Q, BER) for dispersion values used in simulation are -58ps/nm, 23ps/nm, and 100ps/nm for FBG's used at receiver channels. It is observed that FBG used with receiver channels support larger communication fiber length, also G655 (NZDSF) fiber shows much better performance as compared with other SMF's tested. Key Words: FBG, WDM, DCG, DCF, FOM, RZ

Overview of high-speed TDM-PON beyond 50 Gbps per wavelength using digital signal processing [Invited Tutorial]

The recent evolution of passive optical network standards and related research activities for physical layer solutions that achieve bit rates well above 10 Gbps per wavelength ( λ ) is discussed. We show that the advancement toward 50, 100, and 200 G b p s / λ will certainly require a strong introduction of advanced digital signal processing (DSP) technologies for linear, and maybe nonlinear, equalization and for forward error correction. We start by reviewing in detail the current standardization activities in the International Telecommunication Union and the Institute of Electrical and Electronics Engineers, and then we present a comparison of the DSP approaches for traditional direct detection solutions and for future coherent detection approaches.</jats:p

Overview of high-speed TDM-PON beyond 50 Gbps per wavelength using digital signal processing [Invited Tutorial]

The recent evolution of passive optical network standards and related research activities for physical layer solutions that achieve bit rates well above 10 Gbps per wavelength (lambda) is discussed. We show that the advancement toward 50, 100, and 200 Gbps/lambda will certainly require a strong introduction of advanced digital signal processing (DSP) technologies for linear, and maybe nonlinear, equalization and for forward error correction. We start by reviewing in detail the current standardization activities in the International Telecommunication Union and the Institute of Electrical and Electronics Engineers, and then we present a comparison of the DSP approaches for traditional direct detection solutions and for future coherent detection approaches. (c) 2022 Optica Publishing Grou

200 Gbps/λ PON Downstream C-Band Direct-Detection Links with ≥29 dB Power Budget

In this paper we present the simulative analysis of a 200 Gbps per wavelength (λ) 8-level pulse amplitude modulation (PAM-8) downstream communication over up to 20 km single mode fiber (SMF) in C-band based on direct detection (DD) achieving at least a 29 dB link power budget in a PON environment. We use chromatic dispersion digital pre-compensation (CD-DPC) and a dual-arm in-phase and quadrature Mach–Zehnder modulator (IQ-MZM) at the optical line termination (OLT) side, while preserving DD in the optical network unit (ONU). Three receiver digital-signal-processing (DSP) options are analyzed and compared: square-root-like technique (SQRT) in combination with a feed forward equalizer (FFE) and a decision feedback equalizer (DFE), the Volterra nonlinear equalizer (VNLE), and the SQRT in combination with the VNLE. The SQRT can be applied in combination with the VNLE to decrease the receiver DSP complexity while maintaining the required system performance. We show that PAM-8 with CD-DPC and the SQRT in combination with the VNLE is a feasible solution for 200 Gbps per λ downstream C-band transmission for PON