[Purposes]This paper investigates the ultrafast carrier dynamics of Fe doped GaN(GaN:Fe)crystal in the communication band(1 310 nm and 1 550 nm),and elucidates the transient absorption and recombination mechanism of photo-generated carriers from the perspective of semiconductor energy bands.[Methods]Experimental and theoretical research was conducted using femtosecond transient ul-trafast absorption spectroscopy combined with semiconductor band theory.[Findings]The all-optical modulation function of GaN:Fe was achieved by controlling light with light.The experimentally fitted photo-generated carrier recombination lifetime,that is,the optical switching time can be shortened to be-low 10 ps,and the corresponding all-optical modulation rate can be as fast as 50 GHz.[Conclusions]Theoretical prediction shows that under ultra-low pump energy flow of 0.5 mJ/cm2,the modulation depth of GaN:Fe optical switch can reach up to 50%,and it will not be reduced by the increase of Fe doping concentration.The results of this paper provide important scientific references for the application of tran-sition metal doped wide bandgap semiconductors in the field of integrated photonic devices in the future.
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