Tunable two-photon pumped lasing using a holographic polymer-dispersed liquid-crystal grating as a distributed feedback element

A holographic polymer-dispersed liquid-crystal (H-PDLC) grating film was employed as an angle-dependent and narrow spectral-band feedback control element for two-photon pumped lasing in a dye solution, 4-[N-(2-hydroxyethyl)-N-(methyl)amino phenyl]-4′-(6-hydroxyhexyl sulfonyl) stilbene (APSS) in dimethyl sulphoxide. The grating film contained about 80 layers of liquid-crystal domains periodically dispersed in an ∼15 μm thick polymer film, featuring a maximum reflectance of 75% at 561 nm position with an ∼9 nm spectral bandwidth. The output lasing wavelength could be tuned from 561.5 to 548.5 nm and the lasing bandwidth changed from 5 to 3 nm when the incidence angle on the grating film varied from 0° to 22°. The overall lasing efficiency was measured to be 10%.