An enhanced three-dimensional carrier-less amplitude phase (3D-CAP) modulation with information-inserted time slots is proposed in this paper. Compared with the traditional 3D-CAP, the proposed scheme can reduce the value of the up-sampling factor by loading information on the time slots position, thus achieving better bit error rate (BER) performance under the same bit rate. An experiment demonstrating 43.75 Gb/s MIMO-free transmission employing the proposed enhanced 3D-CAP modulation over 2 km weakly coupled 7-core fiber is successfully carried out. The experimental results show that the difference between the best and worst core is about 1.7 dB in receiver sensitivity at a BER of 1 × 10-3 due to the geometrical reason, and the proposed scheme outperforms the traditional 3D-CAP-16 by 2.7 dB in core-1.