Wide-range Electronically Controlled Cholesteric Liquid Crystal Laser

As a self-assembled electrically responsive photonic crystal material,cholesteric liquid crystal(CLC)is one of the most promising intelligent materials in the field of optoelectronics.Dye-doped CLC lasers have great potential application in the fields of sensing,communication and display owing to their advantages of simple structure and manufacture process,small size and adjustability.Both on the multiple structures of cholesteric liquid crystal,band-edge laser and multi-wavelength laser can be obtained.However,the electric field adjust and control based on the cholesteric liquid crystal easily changes the helix axis direction of the system,or even unwinds the helix,making it difficult to achieve wide-range laser regulation and liberate the advantages of electric field.In this paper,the molecular arrangement of dye-doped cholesteric liquid crystal with negative dielectric anisotropy was induced by electric field with different frequencies,and the molecular arrangement structure of cholesteric liquid crystal with different order degree was obtained.Different low-frequency alternating currents(AC)can obtain multi-wavelength lasers with different laser distribution ranges,and the widest range can reach 60 nm at suitable frequencies.Under the high-frequency AC electric field and DC electric field,band-edge laser can be obtained.The switching between multi-wavelength laser and band-edge laser of CLC can be realized and the regulation of the distribution range of multi-wavelength laser can be achieved through frequency control.Multi-wavelength lasers with different distribution range under the induction of low frequency electric field can be obtained using CLCs with different birefringence.It is proved that the bandwidth of photonic band gap is positively correlated with the range of multi-wavelength laser distribution.To some extent,the relationship between the cholesteric liquid crystal structure and the exiting laser is established.Introducing polymer network into the CLC with negative dielectric anisotropic,and driving the liquid crystal molecules with the applying of the DC electric field response of the network,the gradient distribution of the pitch without changing the direction of the helix axis is obtained.At the same time,without changing of the direction of the screw axis,the adjustment and control of bandwidth of photonic band gap can be realized.The Concentration of polymerizable monomer was optimized,and a uniform low-power consumption electrochromic device is therefore obtained with the spectrum substantially covers visible light.Introducing laser dye into the composite system of liquid crystal and polymer network,a tunable multi-wavelength laser is obtained at a low monomer concentration.Denser polymer networks are obtained by increasing the concentration of doped polymerizable monomer.The synergy between the polymer network and liquid crystal molecules is enhanced,and the tunable band-edge laser based on dye-doped PSCLC is obtained.For the single dye doping system,the adjusting range exceeds 110 nm,which almost covers the fluorescent region of the dye.Moreover,the laser adjustment realized by electrically regulated bandwidth broadening is a new method which is different from bandgap shifting.The dye-doped PSCLC laser has characteristics of continuous adjustability,self-restoration,rapid response,temperature stability,and the circular polarization matches with helical structure,which may have diverse applications in the field of intelligent optoelectronics.