Circularly polarized high-efficiency cholesteric liquid crystal lasers with a tunable nematic phase retarder

Abstract

A high efficiency dye-doped cholesteric liquid crystal (CLC) is demonstrated by optimizing the dye concentration and using an electrically tunable nematic liquid crystal (NLC) phase retarder. The state of polarization of laser emission in CLC lasers, contrary to our expectations, due to the refractive index mismatch at the boundaries is not exactly circular. A double-cell structure including a CLC laser and an adjustable NLC phase retarder with a mirror reflector on one of the inner surfaces not only purifies the polarization state of the laser output but also improves the laser efficiency by 6.7X, over the single-direction dye-doped CLC laser.

Achromatic Ellipsometry: Theory and Applications

“…The polarized absorption, on the other hand, can elucidate the molecular order, but does not provide information on circular birefringence effects and Circular Dichroism. The last one consists in the difference between left and right circularly polarized light, thus resulting in the molecular asymmetry [6,8,9]. For instance, the study of energy transfer processes by means of the investigation of emitted polarized light can be very complicated when the polarized state is not completely described.…”

“…In this sense, Emission Ellipsometry (EE) is a technique that, combined with the Stokes theory, allows the complete description of the emitted light polarization states [6,8,9] being, in this manner, an excellent alternative in the study of energy transfer processes, mainly in polymeric materials [2,5,10,11]. In addition, it is possible to obtain full information regarding molecular organization [2,12], anisotropy [10], and asymmetry [13] factors in photoluminescent materials.…”

Light polarization states of a cholesteric liquid crystal probed with optical ellipsometry

“…The well-established dissymmetry factor (g) has been used to characterize the reflected or transmitted circular light polarization state of Ch-LC when circular polarized sources are used [3][4][5]12,[18][19][20][21][22][23][24]. Alternative methods have been applied considering the emission ellipsometry technique in the Stokes theory scope for electromagnetic field [25][26][27][28][29].…”

Thin film polarizer and color filter based on photo-polymerizable nematic liquid crystal

“…1,2 This is an interesting feature which can be used to fabricate color filters, polarizers and lasers. [3][4][5][6][7][8][9][10] We are able to make thin films of these color filters using the photo-polymerization method and by adding appropriate chiral dopant to the liquid crystalline mono(di)acrylate monomers. The bandwidth of reflection is limited to 80nm and the reflectance is at most 50% for unpolarized incident light.…”