A Study On The Electrical Tunable And Lasing Characteristics Of Nematic Liquid Crystal Photonic Crystal Doped With Laser Dye

Basing on the electro-optic birefringence effect of liquid crystal and gain model of the gainmedium laser dye, the control of the photonic crystal defect modes can be realized by change thedirection of the applied electric field, and the optical excitation characteristics of dye dopedphotonic crystal are studied. the electrical tunable and lasing characteristics of nematic liquidcrystal photonic crystal doped with laser dye is numerically simulated.First, the electrical tunable and las ing characteristics of one-dimensional photonic crystalswith dye doped liquid crystal as a defect layer. The physical model is established first, thetransmission and the relationship between transmissivity of defect mode and the gain coefficient isstudied by transfer matrix method. The numerical results show that: when the angle ischanged among0°to90°, the maximum regulation of defect mode wavelength is11nm; after thelaser dye pumped, the position of defect mode will not change, but its transmissivity increases;when the angle is a certain, the transmissivity of defect mode firstly increases and then decreasesas the increasing of the gain coefficient and different defect modes correspond to differentpumping thresholds; the quality factor of the defect modes increase and the correspondingpumping threshold reduce gradually as the increasing of angle.Second, the electrical tunable and lasing characteristics of one-dimensional photonic crystalswith dye doped liquid crystal are studied. The physical model is established first, the transmissionand the relationship between transmissivity of defect mode and the gain coefficient is studied bytransfer matrix method. The results show: comparing with the results of one-dimensional photoniccrystals with dye doped liquid crystal as a defect layer, maximum regulation of defect mode of theone-dimensional photonic crystals with dye doped liquid crystal is much lager; the gain effect ismore obvious and the pumping thresholds are smaller when the pump power is a certain value; thehigher the quality factor is, the lower the pumping threshold is; the on-off function of light whichthe wavelength is a certain value can be realized though changing the applied electric fields.Finally, the electrical tunable and las ing characteristics of the two-dimensional photoniccrystals with dye laser doped liquid crystal are studied. The physical models of perfecttwo-dimensional photonic crystal and dye laser doped liquid crystal photonic crystals are builtfirst; the structure of perfect photonic crystal band-gap, the wave spectrum of dye laser dopedliquid crystal photonic crystals, its threshold characteristic and the optical fields distribution arecalculated by FDTD. The results show: the structure of the perfect two-dimensional photoniccrystals is5835nm-6363nm; the defect mode wavelength shift to the short wavelength; regulationof defect mode wavelength is16nm when the angle changes from0°to90°; the position of thedefect mode does not change after the laser dye pumped, but the strength of the electric fieldchanges; the pumping threshold corresponding to the defect mode decrease gradually, and relativelight intens ity of defect modes changes faster as the increasing of the angle; when pump poweris larger than the pumping threshold, the relationship between relative light intens ity and pumppower is linear; setting the source wavelength to defect mode wavelength, the light field energymainly distribute at the center defect, and the light field energy is lager and distribute moreuniformly as the angle increased.