Continuous tuning of unidirectional emission wavelength by bending a notched-elliptical polymer microdisk.

An approach of continuously tunable unidirectional emission through bending a notched-elliptical polymer microdisk is proposed. The characteristics of the bending-dependent action are carefully analyzed, and the resonance wavelength for unidirectional emission can be tuned continuously through bending the device. Such a whispering-gallery-mode microresonator enables unidirectional emission with ultra-low divergence, of which the emission efficiency and Q factor are stabilized, demonstrating the whole structure is robust and relatively insensitive within a certain bending angle range. A maximum resonance wavelength shift of ∼100 nm and Q factor of 1500 can be achieved with the total size of the microdisk less than 10 μm. This kind of microresonator is promising for applications in multilevel integrated photonics circuits and may open the door to new functionalities of resonator devices, from sensing to optical amplification.