Tuning of polarization-dependent whispering gallery modes in grapefruit microstructured optical fibers infiltrated with negative dielectric anisotropy liquid crystals

An electrically tunable whispering gallery mode (WGM) microresonator based on microstructured optical fibers (MOFs) infiltrated with negative dielectric anisotropy liquid crystals (LCs) is proposed and experimentally demonstrated. Experimental results indicate that the second radial order mode of the MOF microresonator has stronger electric field response than the first radial order mode and the resonance dip for TE polarization mode is more sensitive to the applied electric field intensity in comparison with the TM polarization mode resonance dip. The Freedericksz transition threshold of the proposed MOF microresonator is experimentally found to be about 2.0 V/um. The electrically tunable microresonator integrated with negative dielectric anisotropy LCs is anticipated to find potential applications in optical filtering, all-optical switching, and electrically controlled micro-optics devices.