Liquid-crystal electro-optic switch achieves nanosecond speeds

Researchers at Cambridge University (Cambridge, England) have obtained a contrast ratio of 6.5:1 and an electro-optical response time of 162 ns in a single-pixel liquid-crystal (LC) device filled with an M68 electroclinic mixture based on the Bahr and Heppke A series of chloroester homologs. The researchers increased the switching speed of the homolog above A8 (the fastest in the A series) by mixing A8 with A6 (an analog of A8 with a C₆ alkyl chain substituted for C₈). This mixture provided the LC modulating layer that was sandwiched between an indium tin oxide glass layer and a reflective mirror. The device was tested at a temperature of 75.6°C with a 10-V operating voltage and yielded contrast ratios greater than five for twist angles in excess of 2.5°. The researchers expect device performance to improve with development of a device-fabrication procedure and precise alignment of the LC modulator material. Thickness variation in the LC material must also be controlled to a tolerance on the order of 0.01 mm to maintain the desired resonant behavior. The researchers expect this work to facilitate fabrication of fast-switching multipixel active-silicon-backplane spatial light modulators. Contact Huan Xu at [email protected].