Optically preamplified receiver with low quantum limit

Quantum limit of optimum four-level ASK signals with direct detection optically preamplified receivers.

We analytically obtain the exact fundamental limit of 4-level amplitude shifted keying formats (4ASK) with direct detection optically preamplified receivers. The optimum multilevel spacing and the corresponding decision thresholds, which depend both on the signal to noise ratio and optical bandwidth, are obtained numerically considering the Chi-squared distribution of each level. The quantum li...

Detailed Noise Statistics for an Optically Preamplified Direct Detection Receiver

4Ve describe the exact statistics of an optically preamplified direct detection receiver by means of the moment generating function. The theory allows an arbitrary shaped electrical filter in the receiver circuit. The moment generating function (MGF) allows for a precise calculation of the error rate by using the inverse Fast Fourier transform (FFT). The exact results are compared with the usua...

Performance Evaluation of Optically Preamplified M -

M -ary pulse position modulation (M -ary PPM) has been widely considered as an attractive solution for increasing the bit rates in free-space optical (FSO) communications. Besides increasing the bit rate, M -ary PPM increases the power efficiency of FSO systems. Hence, better performance can be achieved at lower Eb/N0 values when compared to on-off keying (OOK). M -ary PPM systems can be implem...

Optimum Filter Bandwidths for Optically Preamplified NRZ Receivers

We present a comprehensive treatment of optically preamplified direct detection receivers for non-return-to-zero (NRZ) and return-to-zero (RZ) on/off keying modulation, taking into account the influence of different (N)RZ optical pulse shapes, specified at the receiver input, and filter transfer functions; optical Fabry–Pérot filters (FPFs) and Bragg gratings as well as electrical fifth-order B...

Optically Digital Communication and Processing at the Quantum Limit