Low threshold distributed feedback laser based on scaffolding morphologic and holographic polymer dispersed liquid crystal gratings

Abstract

We have made a low scattering holographic polymer dispersed liquid crystal (HPDLC) transmission grating with polymer scaffolding morphology, which was fabricated under the condition of low curing intensity and no liquid crystal droplet. We studied the amplified spontaneous emission (ASE) thresholds and relative intensities of PM567(4, 4-difluoro-1, 3, 5, 7, 8-pentamethyl-2, 6-diethyl-4-bora-3a, 4a-diaza-s-indacene), DCM (4-Dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran), and DCJTI(4-dicyanomethylene)-2-isopropyl-6-(1, 1, 7, 7-tetramethylzulolidyl-9-enyl)-4H-pyran). It is shown that the dye DCJTI has the best properties of ASE, the lowest threshold and the highest relative intensity among the three dyes. Results suggest that DCJIT is a promising material for low threshold, high slope efficiency lasers. Each dye was doped in HPDLC grating with polymer scaffolding morphology individually, and lasers with different wavelengths can be obtained by changing the period of the gratings. The excellent laser property is obtained from the DCJIT-doped laser. A spectral linewidth of 0.3 nm is observed at pump energy threshold 0.65 J/pulse and a conversion efficiency of 1.6% is achieved at the operating wavelength 635 nm. The laser performance is improved in some aspects such as threshold energy, conversion efficiency, and linewidth to some extent as compared with those reported previously.