Transition metal ion-doped cadmium-telluride saturable absorbers for passively Q-switched laser application

Summary form only given. To our knowledge, this is the first report of the saturable absorption properties of Cr-doped, and CoMn-codoped CdTe. TM-doped CdTe has a wider absorption band (/spl sim/1.5-2.5 /spl mu/m for Cr/sup 2+/ and /spl sim/1.4-2.5 /spl mu/m for Co/sup 2+/) compared with TM-doped ZnSe (/spl sim/1.4-1.9 /spl mu/m), and thus they can be operated as saturable absorbers over a wide mid-infrared spectral range. Moreover, a TM-doped CdTe binary compound is easier to grow compared to the CdMnTe ternary compound. We present the saturable absorption properties of Cr-doped, and CoMn-codoped CdTe at 2.09 /spl mu/m, for passive Q-switching. The saturation experiments at room temperature were carried out using a Cr,Tm,Ho:YAG laser. The ground state absorption (GSA) and the excited-state absorption (ESA) cross-sections, and bleaching factors were estimated. Transmittance as a function of energy fluence, without Fresnel loss correction, for Cr:CdTe and CoMn:CdTe are shown. Using Burshtein's model of a slow saturable absorber, where a laser pulse is very short compared with the excited state decay time of the saturable absorber, and considering the background absorption, the bleaching factors of Cr/sup 2+/:CdTe and Co/sup 2+/ and Mn/sup 2+/:CdTe are estimated to be 1.57 and 1.67, respectively.