Dynamically manipulated lasing enabled by a reconfigured fingerprint texture of a cholesteric self-organized superstructure

摘要

Laser emission based on an electrically reconfigured fingerprint texture of a cholesteric liquid crystal helical superstructure is achieved by judiciously designing the composition of the device material and the device structure. Unlike the common lasing, resulting from photonic bandgap behaviour of photons having a certain wavelength in a self-organized liquid crystal helix with a common planar arrangement, the lasing shown herein is caused by a combination of the high-order distributed feedback resulting from periodic refractive index modulation in fingerprint stripes and the waveguide effect of the sandwiched cell structure. Furthermore, this laser, with a narrow bandwidth of less than 0.5 nm, can be switched between two orthogonal emission directions; the emission wavelength as well as the lasing mode (i.e., single-mode, multi-mode and random-mode) can be manipulated readily with a comparatively low external electric stimulation owing to the variety of configurations and reconfigurations possible for such a soft helix. In addition, the lasing can be electrically turned on and off. This study not only corroborates the lasing possibility of a cholesteric liquid crystal helix showing fingerprint texture with a helical pitch significantly exceeding the short pitch required in common photonic band edge lasing, but also simultaneously introduces potential applications in photonic integration and others processes.