Abstract: MgAl2 O4 single crystal optical fiber with 0.5at;Cr3+ ions doped has been grown by laser heated pedestal growth method .The crystal structure and fluorescence temperature characteristics were tested by the X-ray diffraction ( XRD), fluorescence emission spectra and fluorescent decay detection . The results indicate that the main phase of MgAl2O4:Cr3 +single crystal fiber was MgAl2O4 crystal phase, and the spinel crystal structure unchanged with the Cr 3+ions doped .With the increase of temperature , the fluorescence intensity of MgAl 2 O4:Cr3+single crystal fiber decreases under a 405 nm LED excitation. Especially, the intensity of 2 E→4 A2 transition decreases apparently .The fluorescence lifetime of the MgAl2 O4:Cr3+single crystal fiber decreases monotonously from 7.74 ms to 0.5 ms in the temperature range from 293 K to 723 K.The MgAl2 O4:Cr3+single crystal fiber is suitable well for fluorescence sensitized material of optical fiber temperature sensors based on fluorescence lifetime due to the relatively long fluorescence lifetime .

Key words: MgAl2 O4 single crystal optical fiber with 0.5at;Cr3+ ions doped has been grown by laser heated pedestal growth method .The crystal structure and fluorescence temperature characteristics were tested by the X-ray diffraction ( XRD), fluorescence emission spectra and fluorescent decay detection . The results indicate that the main phase of MgAl2O4:Cr3 +single crystal fiber was MgAl2O4 crystal phase, and the spinel crystal structure unchanged with the Cr 3+ions doped .With the increase of temperature , the fluorescence intensity of MgAl 2 O4:Cr3+single crystal fiber decreases under a 405 nm LED excitation. Especially, the intensity of 2 E→4 A2 transition decreases apparently .The fluorescence lifetime of the MgAl2 O4:Cr3+single crystal fiber decreases monotonously from 7.74 ms to 0.5 ms in the temperature range from 293 K to 723 K.The MgAl2 O4:Cr3+single crystal fiber is suitable well for fluorescence sensitized material of optical fiber temperature sensors based on fluorescence lifetime due to the relatively long fluorescence lifetime .