Impact Of Laser Linewidth Research Articles

Analysis of Laser Linewidth on the Performance of Direct Detection OFDM Based Backhaul and Backbone Networks

Abstract Orthogonal frequency division multiplexing (OFDM) is a special form of multicarrier (MC) modulation technique which is adopted in 4G mobile communication systems. The combination of OFDM with passive optical network (PON) architecture is highly desirable for design of flexible and energy efficient backhaul and backbone networks for 5G systems. An intensive mathematical model for linewidth analysis in OFDM based backhaul (BH) and backbone (BB) systems is proposed. The proposed mathematical model includes fiber dispersion, fiber nonlinear effects, amplified spontaneous emission (ASE) noise, transmitter and receiver noises. The impact of laser linewidth in the developed analytical model is analysed in terms phase rotation term (PRT) and inter-carrier interference (ICI) power. Further, the BER performance of the DD-OFDM system as a function of laser linewidth is also presented. The results of the analytical model solved using MATLAB is compared with virtual photonics integrated (VPI) based simulation results. The results of our proposed model suggest that DD-OFDM would perform better for lower linewidth in dispersion uncompensated (DUC) links and it has no impact on the dispersion compensated (DC) links for BB networks. In BH networks, the system performs better for lower linewidth in both DUC and DC links.

Crosstalk Analysis under the Impact of Line-width and Chirp in 8×10 GBPS WDM System Incorporating Optical Cross-Connector

In this paper, a simulative experimental set up for OWDM communication system consist of two 4- optical channels with channel spacing of 0.1THz interconnected by means of a 2x2 OXC (an OXC with 2 input ports and 2 output ports) to route the data with less delay and high throughput is analyzed under the impact of laser line-width and modulator’s chirp over the crosstalk introduced in OWDM system. Our results show that by using OXC, we can minimize the power degradation introduced in OWDM system due to crosstalk. In addition, the impact of laser line-width and modulator’s chirp can not be ignored in reducing the crosstalk while dealing with long haul optical communication systems. The OWDM system is also reported under the influence of crosstalk at different bit rate varying from 1Gbps to 10Gbps in this work.

Impact of Laser Line-width in 40 Gbit/s DWDM Transmission System in the Presence of FWM Incorporating Equal Channel Spacing

The focus of this paper is to investigate a 40 Gbit/s DWDM system over the optical span of 100 km in the presence of Four Wave Mixing (FWM) under the impact of equal channel spacing at varied values of laser line-width. In this proposed work, the performance of DWDM system is carried out by evaluating received electrical power, Q-factor and average eye opening at varied values of equal channel spacing of 0.26 nm and 0.24 nm at laser line-widths of 100 kHz, 10 MHz and 100 MHz under the impact of fiber dispersion.

Analysis of the impact of laser line width over RIN, power penalty and bit rate including higher-order dispersion in WDM systems

This paper investigated the effect of laser line width over relative intensity noise (RIN), power penalty and bit rate at optical distances in the range of 100–10,000 km both analytically and graphically. It is also proposed and analyzed that by reducing the laser line width to the range of KHz, we can minimize the impact of RIN and power penalty under the individual and combined impact of higher-order dispersion parameters.

Laser Linewidth Requirements for Optical DQPSK Systems

A differential quadrature phase-shift-keying (DQPSK) system is analyzed in the presence of additive optical noise and phase noise. In DQPSK, the impact of laser linewidth is frequently neglected: This letter aims to determine whether this assumption is valid. Using asymptotic techniques, we determine the effect that phase noise has on the bit-error rate (BER); this leads to a simple condition for when laser linewidth may be neglected. For a 10-GBd DQPSK system operating at a BER of 10/sup -3/, a linewidth of less than 3 MHz is required for the signal-to-noise-ratio penalty to be less than 0.1 dB.

Impact of Laser Linewidth on Performance of Pre-amplified Optical Direct Detection ASK and M-PPM Systems

A theoretical analysis of optical direct detection M-ary PPM and ASK is provided when an optical preamplifier is used to improve receiver sensitivity considering the effect of laser phase noise, amplifier's spontaneous emission noise and receiver noise. Computed results show that the performace of the system is highly degraded due to the effect of laser phase noise and ASE. The penalty suffered by the system is higher for higher amplifier gain and higher optical bandwidth. However, the effect can be reduced significantly by increasing the PPM order.

Impact of laser linewidth on performance of heterodyne single filter FSK system with optical preamplifier

A quantitative analysis is provided which shows a significant reduction in the sensitivity of the coherent FSK receiver with a semiconductor optical preamplifier in the presence of laser phase noise. The reduction in sensitivity is about 7.0 dB when the linewidth of the laser is only 4% of the bit rate and is higher for larger values of linewidth.

Impact of laser linewidth on optical channel spacing requirements for multichannel FSK and ASK systems

The sensitivity penalty is evaluated for amplitude-shift-keyed and frequency-shift-keyed multichannel coherent systems that use lasers with linewidths which are a significant fraction of the bit rate. The study was conducted for both ASK and FSK systems using a single-filter receiver with nonsynchronous detection. For FSK systems, both NRZ (nonreturn-to-zero) and alternate mark inversion (AMI) signal formats were studied. The optical channel spacing is strongly determined by the laser linewidth. For example, with the FSK-NRZ data rate of 150 Mb/s, the optical channel spacing which gives 1-dB crosstalk penalty is 4 GHz when the intermediate frequency linewidth is 50 MHz (laser linewidth is 25 MHz), as opposed to 1.8 GHz when the linewidth is negligible.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>