The role of the optical front end in the receiver
The optical front end (OFE) is a critical part in most Optical Wireless Communica-tion (OWC) systems. It captures the incoming light flux, converts it and amplifies it into an electrical signal. Its photodiode (PD) and transimpedance amplifier (TIA) can limit the throughput, determined by the noise. In this chapter, we will explore four principal types of front-end designs that are used in optical receivers. LO: local oscillator; PBS: polarization beam splitter; OFE: optical front end, which contains two 90 degree hybrid mixers and four sets of balanced photodiodes.
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