Influence of the excitation area on the thresholds of organic second-order distributed feedback lasers

It is shown that the optical pump power (or energy) density thresholds required to obtain lasing from organic second-order distributed feedback lasers, increase when the excitation area (A) is smaller than a certain value (A(crit)). So, in order to obtain the minimum possible thresholds and to ensure that they constitute adequate quantities for comparison purposes, the condition A > A(crit) should be fulfilled. Results also indicate that when A < A(crit) (A(crit) similar to 0.1 mm(2) for the devices studied here), the operational device lifetime, which depends mainly on the pump power (or energy) density, becomes drastically reduced. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768242]