Spectrally programmable fiber microcavity laser with dye-doped liquid crystals

• Proposing two regimes of fiber microcavity laser emission, i.e., refractive-index-guided laser and gain-guided laser. • Realizing stable tuning of output characteristics of the WGM laser by external field. • Spectrally definable hybrid laser emission was achieved. Envelope shaping and wavelength tuning for resonance modes of lasers have always been promising topics, especially, in extending the functionalities of microcavities which are popular platforms for light confinement and generation. In this paper, a scattering-assisted fiber microcavity laser is proposed with function of spectral shaping. The fiber microcavity supports a liquid crystal micropillar with flexibly controllable scattering, which plays an important role to enhance the laser emission and enable whispering-gallery-mode lasing with variable spectral envelope that is defined by controlling the state of liquid crystal molecules. Our results show that external fields can change refractive index and disorder of the liquid crystal, and the resonant wavelengths of the whispering-gallery-mode laser exhibit opposite tuning regularity under the action of voltage and temperature. Moreover, using a patterned voltage control, spectrally definable hybrid laser emission is realized, laying a solid foundation for the research of spectral programmable soft-materials based lasers.