Yu-Chieh Lin

Optical rotatory power of polymer-stabilized blue phase liquid crystals

Macroscopically, a polymer-stabilized blue phase liquid crystal (BPLC) is assumed to be an optically isotropic medium. Our experiment challenges this assumption. Our results indicate that the optical rotatory power (ORP) of some nano-scale double-twist cylinders in a BPLC composite causes the polarization axis of the transmitted light to rotate a small angle, which in turn leaks through the crossed polarizers. Rotating the analyzer in azimuthal direction to correct this ORP can greatly improve the contrast ratio. A modified De Vries equation based on a thin twisted-nematic layer is proposed to explain the observed phenomena.

Ultra low voltage 1-V RFID tag implement in a-IGZO TFT technology on plastic

This paper has present ultra-low power RFID (Radio-Frequency Identification) tag on plastic foils. The low-power design makes the RFID function easier to implement in flexible transponder. The RFID transponder chip generates 16-bit code and programming in ROM (Read-Only Memory). Digital logic gates were implemented by pseudo-CMOS type and chip processed by lower temperature on a-IGZO (Amorphous-Indium-Gallium-Zinc-Oxide) plastic film. The clock frequency of transponder chip operated at 148.39Hz which consuming only 6.8µW at ultra-low supply voltage of 1V. This plastic chip fabricated on a-IGZO ESL TFTs technology while successfully verified in our display fab and process flow.

Flat panel fingerprint optical sensor using TFT technology

A 3.2×3.0 inch2 optical type fingerprint scanning flat panel is designed and implemented. The driving system is based on the passive pixel sensor (PPS) array with amorphous silicon (a-Si) TFT technology. The sensing layer of the optical sensor is composed of the Si-nanocrystals (Si-NCs) embedded in the dielectric material. The pixel density is over 500 PPI and the gray levels are up to 256 with excellent linearity.