UWB doublet signal generation and modulation based on DFB laser under optical pulses injection

In this paper, a novel scheme to generate ultra-wideband (UWB) doublet signals based on the cross-gain modulation (XGM) effect in the DFB lasers is proposed and experimentally demonstrated, the modulation and transmission of the generated UWB doublet signals are also researched. In the proposed system, a gain-switched laser (GSL) is used as a master laser (ML) and the optical pulses from the ML are optically injected into two paralleled DFB lasers, which are used as slave lasers (SL). Then the outputs from the SLs are detected by a balanced photodiode (BPD) to generate the Bi-phased UWB signals. By properly setting the system parameters, UWB signals with various modulation formats such as on-off keying (OOK), pulse amplitude modulation (PAM) as well as the phase-shift keying (PSK) can be generated. In addition, fiber transmission of the modulated UWB signals is also experimentally investigated.