Sensitivity and power penalty considerations for laser preamplified direct detection optical receivers

1989 ◽  
Vol 136 (4) ◽  
pp. 238 ◽  
Author(s):  
R.S. Fyath ◽  
A.J. McDonald ◽  
J.J. O'reilly

Performance analysis is carried out to evaluate the effect of XPM on a Dispersion Managed (DM) 40Gb/s optical soliton transmission using direct detection, in the presence of Group Velocity Dispersion (GVD), Self-Phase Modulation (SPM), and Amplified Spontaneous Emission (ASE) in this chapter. It is found that for a distance of 2000 km, a power penalty of 1.9 dB is required to achieve a BER of 10-9 when XPM is taken into consideration. This power penalty increases with increasing neighbouring channel power and decreases with increasing channel separation. The system performance is also shown to be dependant on the system dispersion whereby the optimum dispersion is linked to the channel input power.


2020 ◽  
Vol 41 (4) ◽  
pp. 453-461
Author(s):  
Bobby Barua ◽  
S. P. Majumder

AbstractIn this paper, an analytical approach is presented to evaluate the bit error rate (BER) of a free space optical (FSO) link with radio frequency (RF) multiple subcarrier modulation, taking into account the effect of weak atmospheric turbulence considering a direct detection optical receiver followed by RF synchronous demodulator for each sub-channel. Analysis is carried out to find a closed-form expression for conditional BER at the output of the RF demodulators conditioned on a given value of atmospheric turbulence-induced fading and intermodulation distortion (IMD). The average BER for each sub-channel is then found by averaging the conditional BER over the probability density function of the atmospheric turbulence modeled as log-normal distribution. Degradations of BER due to atmospheric turbulence are evaluated for several values of system parameters like number of RF subcarrier, turbulence variance, link distance, data rate and power penalty suffered by the system due to atmospheric turbulence and IMD. For a given system bandwidth, it is found that the maximum power penalty occurs when the subcarrier number is around four and the performance gradually improves with increase in the number of subcarrier. For example, at a system bandwidth of 20 GHz with subcarrier number 4, the power penalty at a BER of 10–9 is found to be 30 dB for a link distance of 3.6 km, whereas the power penalty reduces to 13 dB when the number of subcarrier is increased to 32.


2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Afzal Hossain Hossain

AbstractThe effect of crosstalk due to inter-core coupling on the bit error rate (BER) performance of a fiber optic communication link with a homogeneous multi-core optical fiber (MCF) and a direct detection receiver with optical preamplifier is analytically evaluated and presented in this paper. Coupling coefficients due to inter-core coupling in a 7-core MCF is evaluated numerically with as a function of core-to-core distance (pitch) and relative refractive index contrast. Coupling length is determined against various index contrasts and at different core pitches. Crosstalk power, Signal to Crosstalk plus Noise Ratio (SCNR), BER and power penalty at any output core with light launched into other core of a 7-core MCF are determined analytically. The results show that there is mentionable deterioration in BER performance due to coupling induced crosstalk, and system suffers distinct power penalty at a given BER. For example, power penalty at BER of 10e-9 is found to be 4.0 dB and 4.3 dB for a MCF link of 10 km corresponding to relative refractive index difference of 0.0036 and 0.0030, respectively, for a pitch value of 30 µm and core radius of 4.5 µm.


2017 ◽  
Vol 38 (4) ◽  
Author(s):  
A. K. M. Nazrul Islam ◽  
S. P. Majumder

AbstractAn analytical approach is presented for an optical code division multiple access (OCDMA) system over free space optical (FSO) channel considering the effect of pointing error between the transmitter and the receiver. Analysis is carried out with an optical sequence inverse keying (SIK) correlator receiver with intensity modulation and direct detection (IM/DD) to find the bit error rate (BER) with pointing error. The results are evaluated numerically in terms of signal-to-noise plus multi-access interference (MAI) ratio, BER and power penalty due to pointing error. It is noticed that the OCDMA FSO system is highly affected by pointing error with significant power penalty at a BER of 10


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