Ultra-fast solid state electro-optical modulator based on liquid crystal polymer and liquid crystal composites

A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.

[1]  M. Ozaki,et al.  Tunable Lasing from a Cholesteric Liquid Crystal Film Embedded with a Liquid Crystal Nanopore Network , 2011, Advanced materials.

[2]  K. K. Raina,et al.  Droplet orientation and optical properties of polymer dispersed liquid crystal composite films , 2004 .

[3]  Gordon D. Love,et al.  Phase modulation with polymer-dispersed liquid crystals , 2005, SPIE Optics + Photonics.

[4]  K. Suh,et al.  Electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(methyl methacrylate)/fluorinated liquid crystal microcapsules , 2006 .

[5]  P. Crooker,et al.  Polymer‐dispersed chiral liquid crystal color display , 1990 .

[6]  S. C. Jain,et al.  Electro‐optic response of polymer dispersed liquid‐crystal films , 1991 .

[7]  M. Ozaki,et al.  Deformation‐Free, Microsecond Electro‐Optic Tuning of Liquid Crystals , 2013 .

[8]  K. Suh,et al.  Influence of SMA content on the electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(MMA-co-SMA)/LC microcapsules , 2007 .

[9]  P. Gennes,et al.  The physics of liquid crystals , 1974 .

[10]  Vincent P. Tondiglia,et al.  Electrically switchable volume gratings in polymer‐dispersed liquid crystals , 1994 .

[11]  M. Shau,et al.  Preparation and characterization of PDLC films formed using a two‐step procedure , 2007 .

[12]  Lalgudi V. Natarajan,et al.  Bragg gratings in an acrylate polymer consisting of periodic polymer-dispersed liquid-crystal planes , 1993 .

[13]  Yanlei Yu,et al.  Soft actuators based on liquid-crystalline elastomers. , 2006, Angewandte Chemie.

[14]  Daniele E. Lucchetta,et al.  Phase-only modulation by nanosized polymer-dispersed liquid crystals , 2002 .

[15]  N. Tabiryan,et al.  Self-aligning liquid crystals in polymer composite systems , 2014 .

[16]  R. Vaia,et al.  Two-phase nanoscale morphology of polymer/LC composites , 2001 .

[17]  G. Crawford,et al.  Nematic director‐fields captured in polymer networks confined to spherical droplets , 1994 .

[18]  Shin-Tson Wu,et al.  Inhomogeneous nanoscale polymer-dispersed liquid crystals with gradient refractive index , 2002 .

[19]  R. Shanks,et al.  Thermoplastic polymer‐dispersed liquid crystals prepared from solvent‐induced phase separation with predictions using solubility parameters , 2007 .

[20]  R. Shanks,et al.  Poly(4-vinylpyridine)-based hydrogen bonded side-chain liquid crystal polymers , 2008 .

[21]  Xianyong Wei,et al.  Characterization and Thermal Behaviour of Polymer-Dispersed Liquid Crystals , 2010 .

[22]  R. Shanks,et al.  Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals , 2012 .

[23]  Luciano Vicari,et al.  ELECTRO-OPTIC PHASE MODULATION BY POLYMER DISPERSED LIQUID CRYSTALS , 1997 .

[24]  Yinghan Wang,et al.  RAFT Copolymerization as a means to enhance the electro‐optical performance of polymer dispersed liquid crystal films , 2007 .

[25]  Boris Zeldovich,et al.  High-efficiency 1.5 microm thick optical axis grating and its use for laser beam combining. , 2007, Optics letters.

[26]  K. Lim,et al.  Effects of off-state alignment in polymer dispersed liquid crystals , 1989 .

[27]  K. Kubodera,et al.  Fine droplets of liquid crystals in a transparent polymer and their response to an electric field , 1996 .

[28]  D. Broer,et al.  INSITU PHOTOPOLYMERIZATION OF ORIENTED LIQUID-CRYSTALLINE ACRYLATES .3. ORIENTED POLYMER NETWORKS FROM A MESOGENIC DIACRYLATE , 1989 .

[29]  Paul Drzaic,et al.  Liquid Crystal Dispersions , 1995 .