A performance study of Nd-based stoichiometric random lasers

Abstract

Rare earth stoichiometric powder hosts have received the most attention for random laser (RL) action1,2. In contrast to other laser hosts where the active ion is dispersed as a dopant in a crystalline matrix, stoichiometric hosts are pure chemical compounds of rare earth (RE) ions. In principle, the main variable that controls the quenching of the desired luminescence is the non-radiative energy transfer process between RE ions. In a microsecond time scale the high concentration of Nd3+ ions might give rise to short-range spatial energy transfer in the metastable level, as well as to long-range spatial energy migration among Nd3+ ions and thus, huge losses might be expected which would affect the threshold and slope efficiency for laser action. However, the fast build up of the random laser pulse makes the nonradiative losses produced by quenching concentration much less important than in a conventional laser. This work presents a comparative study of the random lasing performance of several Nd based stoichiometric compounds, together with a discussion about the fundamental parameters which control their random laser operation. On the other hand, we demonstrate that Nd-based crystal powder random laser provides Speckle-free transmission and reflection infrared images with higher values of contrast to noise ratio (CNR) than those obtained with the narrowband laser. These results open up new possibilities to enhance the field of high resolution imaging for optoelectronic and biomedical applications