Abstract-In this letter, we propose a low-density parity-check coded hybrid subcarrier/amplitude/phase/polarization (H-SAPP) modulation scheme suitable to achieve a 240-Gb/s single-channel transmission rate over optical channels. The proposed scheme doubles the aggregate transmission rate achievable by eight-quadrature amplitude modulation while providing 2-dB optical signal-tonoise ratio performance improvement at a bit-error-ratio (BER) of 10 6 . Moreover, H-SAPP can increase the aggregate rate of the hybrid amplitude/phase/polarization scheme while maintaining the BER performance intact.Index Terms-Coherent detection, high-speed optical transmission, hybrid subcarrier/amplitude/phase/polarization (H-SAPP) coded modulation, low-density parity-check (LDPC) codes, optical communications.