The vast acceptance of OFDM technology is not limited to the radio domain, but is also among researchers for wireline and wireless optical communications. For indoor wireless optical communications, the use of OFDM faces a major challenge in reducing the average transmit optical power to cope with the eye safety problem. We propose the use of the selected mapping (SLM) technique to reduce the average transmit optical power in indoor WOC systems. In particular, SLM is investigated by employing five different families of phase sequences, namely chaotic, Shapiro-Rudin, pseudo-random interferometry code (PRIC), Walsh-Hadamard, and random sequences. Simulation results indicate the attractiveness of chaotic and Shapiro-Rudin sequences in terms of the reduction in the average transmit power with the computational complexity that grows linearly with the number of OFDM subcarriers.