Relative Intensity Noise in Optical Single Side Band Systems with Multiple In-Line Amplifiers: Analysis and Validation

Abstract

This article analyzes and validates through simulation the influence of fiber nonlinearity, dispersion, and loss on the Relative Noise Intensity (RIN) spectrum at fiber output in externally modulated optical single side band (OSSB) systems. The analysis includes the RIN generated by the laser source, the effect of the OSSB modulator, and noise generated by the in-line optical amplifiers. The analysis takes into account conversion between phase noise and intensity noise introduced by fiber transmission. It is shown that, depending on the operating conditions, the system performance may be predominantly affected either by the laser RIN or by the noise generated by the in-line optical amplifiers. The impact of the OSSB modulator can be relevant when the RIN of the system is dominated by the laser noise and should therefore be considered.

Impact of Optical Transmission on Multiband OFDM Ultra-Wideband Wireless System With Fiber Distribution

“…It is well known that laser RIN can be enhanced by group velocity dispersion in optical fiber. In addition, previous work shows that laser RIN due to phase to intensity noise conversion by fiber dispersion is directly proportional to the laser linewidth [30][31]. Calculated spectral density of RIN as a parameter of frequency for the laser source depicted in Fig.…”

“…where, A^ =128 is the total number of subcarrier used, Af = BW/N = 4.125 MHz is the subcarrier frequency spacing, n is the subcarrier number, T cp =60.61 ns is the cyclic prefix, T FFT =\/Af = 242.42ns is the IFFT/FFT period, and BW is the signal bandwidth. 31…”

“…Itis seen that shot noise, RJN and signal-ASE beat noise are the major sources of noise at the receiver for higher optical power. Noise power level at the receiver versus received optical power for back-to-Calculated total RIN versus fiber length.IllFiber dispersion changes the laser RIN due phase noise to intensity noise conversion[30][31].Figure A.2shows total relative intensity noise due to fiber dispersion for a laser with linewidth of &co/{2n:)= 800 KHz at 1550 nm by using[30] RIN(L) = RIN(0) + 1^^^s m 2^j 3 2 Ln 2 )dn(A.2)where (Q u -Q-^/ln-BW is the signal occupied bandwidth, L is the fiber length and RIN(0) = -155 dB/Hz is the laser intrinsic RIN.…”