Optically pumped lasers based on solution-processed thin-film gain media have recently emerged as low-cost,broadly tunable,and versatile active photonics components that can fit any substrate and are useful for,e.g.,c...Optically pumped lasers based on solution-processed thin-film gain media have recently emerged as low-cost,broadly tunable,and versatile active photonics components that can fit any substrate and are useful for,e.g.,chemo-or biosensing or visible spectroscopy.Although single-mode operation has been demonstrated in various resonator architectures with a large variety of gain media-including dye-doped polymers,organic semiconductors,and,more recently,hybrid perovskites-the reported linewidths are typically on the order of a fraction of a nanometer or broader,i.e.,the coherence lengths are no longer than a few millimeters,which does not enable high-resolution spectroscopy or coherent sensing.The linewidth is fundamentally constrained by the short photon cavity lifetime in the standard resonator geometries.We demonstrate here a novel structure for an organic thin-film solid-state laser that is based on a vertical external cavity,wherein a holographic volume Bragg grating ensures both spectral selection and output coupling in an otherwise very compact(,cm3)design.Under short-pulse(0.4 ns)pumping,Fourier-transform-limited laser pulses are obtained,with a full width at half-maximum linewidth of 900 MHz(1.25 pm).Using 20-ns-long pump pulses,the linewidth can be further reduced to 200 MHz(0.26 pm),which is four times above the Fourier limit and corresponds to an unprecedented coherence length of 1m.The concept is potentially transferrable to any type of thin-film laser and can be ultimately made tunable;it also represents a very compact alternative to bulky grating systems in dye lasers.展开更多
基金the Agence Nationale de la Recherche(grant ANR-12-EMMA-0040‘‘Vecspresso’’project)the Region Ile de France(DIMNano’K)the LABEX SEAM for funding this work.
文摘Optically pumped lasers based on solution-processed thin-film gain media have recently emerged as low-cost,broadly tunable,and versatile active photonics components that can fit any substrate and are useful for,e.g.,chemo-or biosensing or visible spectroscopy.Although single-mode operation has been demonstrated in various resonator architectures with a large variety of gain media-including dye-doped polymers,organic semiconductors,and,more recently,hybrid perovskites-the reported linewidths are typically on the order of a fraction of a nanometer or broader,i.e.,the coherence lengths are no longer than a few millimeters,which does not enable high-resolution spectroscopy or coherent sensing.The linewidth is fundamentally constrained by the short photon cavity lifetime in the standard resonator geometries.We demonstrate here a novel structure for an organic thin-film solid-state laser that is based on a vertical external cavity,wherein a holographic volume Bragg grating ensures both spectral selection and output coupling in an otherwise very compact(,cm3)design.Under short-pulse(0.4 ns)pumping,Fourier-transform-limited laser pulses are obtained,with a full width at half-maximum linewidth of 900 MHz(1.25 pm).Using 20-ns-long pump pulses,the linewidth can be further reduced to 200 MHz(0.26 pm),which is four times above the Fourier limit and corresponds to an unprecedented coherence length of 1m.The concept is potentially transferrable to any type of thin-film laser and can be ultimately made tunable;it also represents a very compact alternative to bulky grating systems in dye lasers.
