Error performance analysis for an optical heterodyne FSK communication system with a limiter-discriminator-integrator detector

Abstract

The error probability for a coherent optical heterodyne FSK system with a limiter-discriminator-integrator (LDI) detector is analysed. The analysis includes laser quantum phase noise, the correlated receiver additive white Gaussian noise (AWGN), Gaussian narrow-band IF filtering and intersymbol interference (ISI) caused by it. It is shown that, for 1 dBEb/N ₀penalty at bit error rate (BER) 10⁻⁹, (i) the normalized IF beat spectral linewidth ΔνT⩽0.35% for frequency deviation ratioh=0.5(MSK), and ΔνT⩽0.5% forh=0.7 (the receiver is insensitive to laser quantum phase noise ath=1.0, if ISI is not included.); (ii) if ISI is incorporated, ΔνT⩽0.15% forh=0.5, ΔνT⩽0.5% forh=0.7, both with 3dB bandwidth-bit period product (3.0>BT⩾1.5), and ΔνT⩽0.5% forh=1.0 with BT⩾1.0 ifΔνT⩽0.35% when ISI exists,h=0.7 is optimum;h=1.0 otherwise.