Abstract

The range of transmitters, detectors and other components that can be used in optical wireless links means that they can have a wide variety of frequency responses. Both pre- and post- equalization have been used in optical wireless systems to increase data rates. Pre-equalization has the advantage that noise impairments due to equalization can be minimised. However, the variety of pre-equalizer transfer functions, which can be easily created using analog circuits, is limited by the frequency responses of these circuits. Consequently, it may not be possible to equalize some optical wireless links with analog circuit-based pre-equalizers. In this paper a flexible digital pre-equalization scheme that can equalize complex frequency responses is described. The flexibility and the applicability of the scheme is also demonstrated using two example systems, including one that incorporates a fluorescent optical fiber to create a wide-field-of-view receiver for handheld devices. In particular, the bandwidths of the two example systems have been increased to over 500 MHz and to 350 MHz, resulting in at least a three-fold increase in data rate without any post-equalization. The authors believe that this is the first time such significant improvements in on-off-keying data rates have been demonstrated in systems with a relatively complex frequency response and a limited dynamic range.

Pre-equalization technique enabling 70 Gbit/s photonic-wireless link at 60 GHz

F. C. Abrecht, R. Bonjour, S. Welschen, A. Josten, B. Baeuerle, D. Hillerkuss, M. Burla, and J. Leuthold
Opt. Express 24(26) 30350-30359 (2016)

Series-connected solar array for high-speed underwater wireless optical links

Zhijian Tong, Xingqi Yang, Hao Zhang, Yizhan Dai, Xiao Chen, and Jing Xu
Opt. Lett. 47(5) 1013-1016 (2022)

56-m/3.31-Gbps underwater wireless optical communication employing Nyquist single carrier frequency domain equalization with noise prediction

Xiao Chen, Weichao Lyu, Zejun Zhang, Jian Zhao, and Jing Xu
Opt. Express 28(16) 23784-23795 (2020)

Time-domain digital pre-equalization for band-limited signals based on receiver-side adaptive equalizers

Junwen Zhang, Jianjun Yu, Nan Chi, and Hung-Chang Chien
Opt. Express 22(17) 20515-20529 (2014)

Performance improvement of optical wireless communication through fog with a decision feedback equalizer

Marius Aharonovich and Shlomi Arnon
J. Opt. Soc. Am. A 22(8) 1646-1654 (2005)