  We propose two transceiver schemes based on Kramers Kronig (KK) detection.
One targets low-cost high-throughput applications and uses PAM transmission in
combination with direct detection and digital reconstruction of the optical
phase. This scheme allows digital compensation of chromatic dispersion and
provides a significant improvement in terms of spectral efficiency, compared to
conventional PAM transmission. The second scheme targets high-channel-count
coherent systems with the aim of simplifying the receiver complexity by
reducing the optical components count.
