Slope efficiency characteristics of mode-hop driven tunable single-mode cholesteric liquid crystal laser

Abstract

We report tunable single-mode lasing with an improved slope efficiency from a cholesteric liquid crystal (ChLC) cavity with a three-layered structure. The device consists of one photopolymerized ChLC layer with a wide reflection band, another ChLC layer with a notch reflection band and a Rhodamine-6G-doped ionic liquid layer acting as the gain medium. Single-mode lasing can be obtained in this device structure because the ChLC layer with the notch reflection band strongly reflects only one of the Fabry-Perot cavity modes. Tuning of the lasing wavelength is achieved by tuning the reflection band of the notch ChLC. The device showed a maximum slope efficiency of 16%, which was found to be approximately 1.5 times larger than that of ordinary ChLC lasers doped with the pyrromethene 597 laser dye.

Continuously tuneable laser in the full visible spectrum formed in 10 minutes with cholesteric liquid crystal cells based on the electrothermal effect

“…The centre wavelength λc in the PBG is equal to P×(no+ne)/2. The PBG position can be adjusted through the pitch and refractive index of NLCs by altering the relative weight ratio of the chiral material to the NLC 4,2,5 , temperature [6][7][8] , or external electric field [9][10][11][12][13] or through photoinduced trans-cis isomerization [14][15][16] . To date, various types of CLC laser devices have been developed 17,18 , and many excellent results have been reported.…”