Abstract

A theory for the signal-to-noise ratio (SNR) of optical direct-detection receivers employing return-to-zero (RZ) coding (and possibly optical preamplification) is developed. The results are valid for both signal-independent noise limited and signal-dependent noise limited receivers, as well as for arbitrary optical pulse shapes and receive filter characteristics. Even if the same receiver bandwidth is used, RZ coding is seen to perform better than nonreturn-to-zero (NRZ) coding. Asymptotic expressions for the SNR in case of very high and very low receiver bandwidths show that the full sensitivity enhancement potential of RZ coding is exhausted at fairly moderate duty cycles. A realistic example taking into account intersymbol interference (ISI) shows that a receiver sensitivity gain (compared to NRZ coding) of, e.g., 3.2 dB can be obtained in a signal-independent noise limited receiver with a bandwidth of 80% of the data rate, using a duty cycle of three.

[IEEE ]

Receiver sensitivity of type-II return-to-zero signals having finite extinction ratios

Jihoon Lee and Hoon Kim
Opt. Express 30(23) 42594-42604 (2022)

Receiver sensitivity of type-I return-to-zero signals having finite extinction ratios

Jihoon Lee and Hoon Kim
Opt. Express 31(9) 13724-13738 (2023)

Optical sampling to enhance Nyquist-shaped signal detection under limited receiver bandwidth

Zihan Geng, Deming Kong, Valery Rozental, Arthur James Lowery, and Bill Corcoran
Opt. Express 27(17) 24007-24017 (2019)

Sensitivity modeling of binary optical receivers

Dirk Giggenbach and Ramon Mata-Calvo
Appl. Opt. 54(28) 8254-8259 (2015)

Optical receiver sensitivity enhancement by single- and dual-band fiber optical parametric amplifier

Jiqiang Kang, M. E. Marhic, Bowen Li, Sisi Tan, Xie Wang, and Kenneth K. Y. Wong
Opt. Express 25(22) 27785-27794 (2017)