Optical nonlinearity and photoluminescence in CuI doped glass

CuI embedded in borosilicate glasses are prepared by a melt and heat-treatment method. We obtain the free carrier absorption cross section σ ≈ 1.0 × 10−17 cm2 and the two-photon absorption coefficient β ≈ 0.14 cm/GW by means of the Z-scan method using 6-ns laser pulses at 532 nm, with an irradiation I0 ≈ 16 MW/cm2. Upon excitation with 355 nm laser pulses at room temperature, very bright luminescence is observed, while the peak position shifts to lower energy as the band gap of CuI decreased by crystal growth. We also observed that the peak intensity varies linearly with the input intensity. The results could be attributed to the radiative recombination associated with traps or defects from impurities in the CuI microcrystallites.