The digital pulse interval modulation (DPIM) has a higher requirement on the buffer performance compared with the fixed length modulations. So a novel fixed length dual duration digital pulse interval modulation (FDD-DPIM) is presented, and its symbol structure is introduced as well. Through simulations and experiments, the bandwidth requirement, average transmission power and error rate performance of the FDD-DPIM are analyzed compared with those of the binary on-off keying (OOK), DPIM, fixed-length digital pulse interval modulation (FDPIM), fixed length dual-amplitude pulse interval modulation (FDAPIM) and dual-amplitude fixed length digital pulse interval modulation (DAFDPIM). The results show that the FDD-DPIM offers higher bandwidth efficiency and average transmission power, and has better error rate performance than the DAFDPIM. Hence, it is believed to be suitable in the visible light communications (VLC) application.