High Bit Rate Pulse Position Modulation Signal Generation Based on Rare-Earth-Doped Crystals

A novel approach for generating a high bit rate m-ary pulse position modulation (PPM) signal is proposed. This approach is implemented by using two temporally overlapping linear frequency chirps (TOLFC) and multiple probe pulses interact with rare-Earth-doped crystal (REIC). By simply adjusting the start frequency of the probe pulse, the time interval of compressed pulse in the PPM signal was controlled. The relationship between the time interval of compressed pulse and the start frequency shift of probe pulse is theoretically analyzed and verified by simulation. In the last part, a simulation is performed, which shows a 4-PPM signal at a bit rate of 10 Gbit/s by using the aforementioned method.