Spatial tuning of laser emission in a dye-doped cholesteric liquid crystal wedge cell

Spatial tuning of lasing wavelength in a dye-doped cholesteric liquid crystal wedge cell is demonstrated. The wedge cell possesses a series of dislocation lines along the wedge direction. In the lasing operation, we find that the lasing wavelength is continuously tuned in the region between two dislocation lines, while the lasing wavelength jumps when crossing the dislocation lines. The observed one-dimensional spatial continuous tuning is attributed to the presence of a gradient in the cholesteric helical pitch, while the laser wavelength jumping originates from the pitch jump owing to a change in the number of half-turns of the cholesteric helix.