IETOptoEl20 – EML

The rapid growth of digital services has led to a widespread deployment of opto-electronics that furnish the Internet
as an efficient communication backbone. The electroabsorption-modulated laser (EML) is a representative example of a
monolithic integrated electro-optic converter that has early become a commodity: it has been widely adopted in
telecommunication networks in virtue of its cost- and energy-efficient light generation and modulation. This study reviews the
state-of-the-art of EML applications. Despite its simplicity, the EML addresses numerous use cases that require either the
transmission or the reception of optical signals, such as equaliser-free high-bandwidth intensity modulation/direct-detection links
at low signal drive, analogue signal transmission with high signal integrity, spectral sculpting for dispersion-tolerant transmission
and vector modulation. Full-duplex transceiver functionality in lieu of a pair of dedicated half-duplex sub-systems is eventually
attained by combining transmission and reception. This strategy of significantly reducing the cost for a bidirectional
communication engine will be discussed for coherent digital data and analogue radio-over-fibre transmission and optical
ranging. The maturity of EMLs as coherent transceivers will be evidenced by a small penalty for realising full-duplex
transmission and the accomplishment of homodyne detection, which obviates digital signal processing for the purpose of signal
recovery.