  Coherent technology inherent with more availabledegrees of freedom is deemed
a competitive solution for nextgeneration ultra-high-speed short-reach optical
interconnects.However, the fatal barriers to implementing the
conventiona.coherent system in short-reach optical interconnect are the
costfootprint, and power consumption. Self-homodyne coherentsystem exhibits its
potential to reduce the power consumption ofthe receiver-side digital signal
processing (Rx-DSP) by deliveringthe local oscillator (LO) from the
transmitter. However, anautomatic polarization controller (APC) is inevitable
in the remoteLO link to avoid polarization fading, resulting in additional
costsTo address the polarization fading issue, a simplified self.homodyne
coherent system is proposed enabled by Alamouticoding in this paper. Benefiting
from the Alamouti coding betweentwo polarizations, a polarization-insensitive
receiver onlyincluding a 3dB coupler, a 90o Hybrid, and two balancedphotodiodes
(BPDs)is sufficient for reception. Meanwhile, theAPC in the LO link is
needless, simplifying the receiver structuresignificantly. Besides, the digital
subcarrier multiplexing (DSCM)technique is also adopted to relax the
computational complexity ofthe chromatic dispersion compensation (CDC), which
is one of thedominant power consumption modules in Rx-DSP. Thetransmission
performance of 50Gbaud 4-subcarrier 16/32OAM(4SC-16/320AM) DSCM signal based on
the proposed simplifiedself-homodyne coherent system is investigated
experimentallyThe results show that the bit-error-ratio(BER)
performancedegradation caused by CD can be solved by increasing 4 taps inthe
equalizer for 80km single mode fiber(SMF)transmissionwithout individual CDC,
which operates in a low-complexitymanner.
