10.1117/2.1201412.005595 Photo-aligned ferroelectric liquid crystals for modern photonics Abhishek Kumar Srivastava, Vladimir Chigrinov, and Hoi-Sing Kwok A photo-aligned, electrically-suppressed-helix ferroelectric liquid crys- tal enables high optical quality, shock stability, and low driving voltage, showing promise for application in future displays. The latest demands of the optoelectronics industry, which has undergone drastic change in recent years, include increasingly high-resolution displays and cost-effective photonic devices with reduced power consumption. Due to the high cost of the relevant materials and fabrication methods, these requirements present a huge challenge. Ferroelectric liquid crystals (FLCs), which are capable of fast switching speeds at low driving volt- ages, represent a promising candidate for the realization of such devices. However, due to several limitations (e.g., geometrical, optical, and mechanical instabilities), FLC structures are cur- rently less popular than nematic and other liquid crystals. 1–5 In FLCs, the smectic layers (characterized by molecules that self-organize into parallel sheets) lie perpendicular to the glass substrate. This alignment is easily destroyed by thermal undula- tions or mechanical shock, which can degrade the optical quality in FLCs. Another critically important effect that must be over- come is diffraction in the dark state of the FLC cell. 4 This diffrac- tion is caused by the periodic structure of the material, which is created by both the ferroelectric domains and the helical pitch of the system. Such diffraction is a core issue for projection displays and photonic elements. The dark state diffraction can be reduced by decreasing the spontaneous polarization and alignment conditions, thereby suppressing the ferroelectric domains. 5 Moreover, we have re- cently discovered that good optical quality can be achieved in FLCs with a helical pitch smaller than their cell thickness, in association with photo-alignment by irradiation. This combina- tion leads to high contrast without the generation of diffrac- tion lobes. Our nanoscale photo-alignment process relies on the Figure 1. (a) Electric field dependence of the response time () and frequency dependence of the optical contrast (ı) in our electrically- suppressed-helix ferroelectric liquid crystal (ESHFLC) cells, at a driving voltage of 1.5V/m. Examples of the (b) 24-bit colors and (c) color images obtained using ESHFLCs. (d) The color triangle of the ESHFLC display (larger triangle) compared to the NTSC gamut (gray triangle). (e) The image quality before, during, and after mechanical pressure, showing no deterioration. 6, 7 Continued on next page