Abstract

Thin-film organic solid-state lasers (OSSLs) have recently emerged as potential low-cost alternatives to dye lasers, OPOs and supercontinuum sources to provide widely-tunable coherent radiation over the whole visible spectrum [1]. Organic gain chips can be processed at low cost with thin-film techniques (spin casting or inkjet printing), and OSSLs may find useful application in spectroscopy and sensing. However, as electrical pumping is still an open challenge, OSSLs are generally optically pumped by frequency-doubled or tripled solid-state lasers, which are bulky and much more expensive than the organic laser structure itself, jeopardizing the promises of a truly low-cost system. The recent spectacular progress in high power inorganic blue laser diodes (LD) and light-emitting diodes (LED) enabled the demonstration of OSSLs pumped by those sources, but nevertheless, as the peak power of laser diodes (and all the more LEDs) is weak compared to the values achieved with pulsed solid-state lasers, very low threshold laser resonators such as distributed feedback (DFB) or microcavities have been, up to now, used for diode pumping [2]. As low threshold operation involves a low output coupling, the reported output powers of such diode-pumped lasers are very low (either given in arbitrary units or when measured, in the pJ or nJ range) and the only reported optical-to-optical efficiencies range around 1%. Furthermore, DFB low-loss compact resonators do not generally provide a diffraction-limited output beam, leading to a weak brightness, which is especially problematic for applications requiring a free-propagating beam, such as absorption or Raman spectroscopy.

© 2015 IEEE