Dual-Wavelength Lasing with Orthogonal Circular Polarizations Generated in a Single Layer of a Polymer–Cholesteric Liquid Crystal Superstructure

Abstract

We investigate the laser emission from a polymer–cholesteric liquid crystal superstructure with coexisting opposite chiralities fabricated by refilling a right-handed polymeric scaffold with a left-handed cholesteric liquid crystalline material. The superstructure exhibits two photonic band gaps corresponding to the right- and left-circularly polarized light. By adding a suitable dye, dual-wavelength lasing with orthogonal circular polarizations is realized in this single-layer structure. The wavelength of the left-circularly polarized laser emission is thermally tunable, while the wavelength of the right-circularly polarized emission is relatively stable. Due to its relative simplicity and tunability characteristics, our design might have broad application prospects in various fields of photonics and display technology.

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses

“…Various CLC materials and structures have thus been developed to implement tunable reflective colors in a varying degree of wavelength tunability by modulating the CLC pitch directly through temperature variations [ 1 , 2 ], light irradiation [ 3 , 4 , 5 ], and applied voltage [ 6 , 7 , 8 ], or indirectly through electrothermal [ 9 , 10 , 11 , 12 ], mechanical [ 13 , 14 ], and hydrodynamic [ 15 ] effects. Due to their uniqueness, CLCs have been extensively exploited or introduced for numerous applications, including in color filters [ 16 , 17 ], lasers [ 18 , 19 ], reflective displays [ 20 , 21 ], reflective polarizers [ 22 , 23 ], sensors [ 24 , 25 , 26 , 27 , 28 ], and smart windows [ 29 , 30 , 31 ]. However, as birefringence in CLCs is typically lower than 0.2 and only one of the two circularly polarized components of light can be reflected, a CLC bandgap is inherently limited to reflect unpolarized light colors within a narrow bandwidth with a reflectance R % less than 50%.…”

Electrically Tunable Two-Color Cholesteric Laser

“…One of the very attractive control methods is tuning via an applied electric field; however, its full potential has not yet been achieved [ 19 ]. Recently, several approaches to achieve lasing at different wavelengths have been demonstrated using a CLC multilayer system [ 20 ], emulsified polymer-dispersed liquid crystals (PDLCs) [ 21 ], CLC spherical micro-shells [ 22 ], and a defect mode laser structure [ 23 ] and topological lasing [ 24 ]. For instance, Barberi et al demonstrated multi-wavelength lasing through a combination of a photoluminescent dye layer and three cholesteric layers [ 20 ].…”

“…For instance, Barberi et al demonstrated multi-wavelength lasing through a combination of a photoluminescent dye layer and three cholesteric layers [ 20 ]. Multi-wavelength lasing from a polymer–cholesteric liquid crystal superstructure with coexisting opposite chiralities was also obtained by refilling a right-handed polymeric scaffold with a left-handed cholesteric liquid crystal material [ 23 ]. In addition, robust topological interface state lasing at multiple wavelengths of the visible spectrum in a micron-sized polymer-cholesteric liquid crystal superlattice was also demonstrated [ 24 ].…”