Abstract

Chiral smectic liquid crystals (CSLCs) have microsecond response times due to a first order coupling between their macroscopic polarization and an applied electric field. With homeotropic alignment of the liquid crystal molecules direct analog phase modulation is obtained. [1] The significance of this device structure is that these materials can be fabricated in a Fabry-Perot (FP) cavity, making continuous optical wavelength tuning possible. This results in a low cost, microsecond tuning speed, narrow passband resolution, and potentially large tuning range optical filter for wavelength-divisionmultiplexing based lightwave networks, such as IBM Rainbow Network. [2] The proof-of-principle filter consists of two optical flats coated with mirrors (R= 97%) separated by metal films that operate as both a spacer (2 to 25 pm) and electrode. The cells were then heated up to 100° C and filled with CSLC in its isotropic phase by capillary action. Preliminary results suggest the tuning range is approximately 30 nm with a switching speed of a few psec at λ = 1.55 pm.

© 1993 Optical Society of America