In this paper, Gigabit per second transmission over short-range step-index plastic optical fibre (SI-POF) is implemented with multi-level pulse amplitude modulation (PAM-M) scheme using a laser diode (LD) as the optical source. In particular, the POF channel distortion and the non-linear distortion from the LD are considered. To mitigate these distortions under various PAM-M levels, the bit error rate (BER) performances of the transversal, Volterra and multi-layer perceptron (MLP) based decision feedback equalizers are evaluated and compared. Furthermore, the inverse polynomial technique for non-linear mitigation is also considered. MLP is shown to offer the best BER performance for PAM scheme using more than eight levels especially for a system with high non-linearities. With the MLP equalizer, we record the highest data rate of 3, 7.8, and 18 Gbps for POF lengths of 60, 30, and 10 m, respectively.