Laterally azo-bridged h-shaped ferroelectric dimesogens for second-order nonlinear optics: ferroelectricity and second harmonic generation.
Two classes of laterally azo-bridged H-shaped ferroelectric liquid crystals (FLCs), incorporating azobenzene and disperse red 1 (DR-1) chromophores along the FLC polar axes, were synthesized and characterized by polarized light microscopy, differential scanning calorimetry, 2D X-ray diffraction analysis, and electro-optical investigations. They represent the first H-shaped FLC materials exhibiting the ground-state, thermodynamically stable enantiotropic SmC* phase, i.e., ground-state ferroelectricity. Second harmonic generation measurements of one compound incorporating a DR-1 chromophore at the incident wavelength of 1064 nm give a nonlinear coefficient of d(22) = 17 pm/V, the largest nonlinear optics coefficient reported to date for calamitic FLCs. This value enables viable applications of FLCs in nonlinear optics.
Zhang
Yongqiang
Y
Displaytech Inc., 2602 Clover Basin Drive, Longmont, Colorado 80503, USA. yqzhang@micron.com
Martinez-Perdiguero
Josu
J
Baumeister
Ute
U
Walker
Christopher
C
Etxebarria
Jesus
J
Prehm
Marko
M
Ortega
Josu
J
Tschierske
Carsten
C
O'Callaghan
Michael J
MJ
Harant
Adam
A
Handschy
Mark
M