Microfluidic generation of cholesteric liquid crystal droplets with an integrative cavity for dual-gain and controllable lasing

The integration of one more gain media in droplet microlasers with morphology-dependent modes, which can be employed in optofluidic systems as multi-wavelength lasing sources, is highly attractive and demands new cavity design and fabrication approaches. Here, cholesteric-liquid-crystal (CLC) droplets with an integrative triple-emulsion cavity are fabricated via glass-capillary-based microfluidic technologies and the dual-gain lasing with variable modes is flexibly configured by the combination and incorporation of gain dyes and CLCs into both core and shell. The distributed feedback (DFB) mode formed by the feedback of self-assembled helix periodic structure of CLCs, the whispering gallery (WG) mode, and the hybrid, are selectively excited by controlling the spatial coupling between the pump beam and the droplet with gain. With merits of dual-gain and controllable lasing, a prototype of dual-wavelength-ratiometric thermometer with self-calibration capability is expected to be developled. Furthermore, the anisotropic CLC core is substituted with an isotropic fluid and the gain from CLC shell is additionally removed, DFB lasings in both shell and core are absent and only Bragg-shell reflection-based hybrid modes are excited for lasing. The CLC droplet microlasers with an integrative cavity are expected for routing a new way to future lab-on-chip (LOC) applications.