High Performance Liquid Crystals for Laser Communications
Abstract
During the course of this contract, we have developed several new olefin diphenyl-diacetylene and bistolane liquid crystals for laser communications. The olefin diphenyl-diacetylenes, synthesized by Mary Neubert's group of Kent State University, exhibit a much wider pnematic range than the corresponding alkyl homologues. The high clearing point of the olefin compounds helps to increase the birefringence and figure-of-merit through higher order parameter. A sample eutectic mixture consisting of such olefin diphenyl-diacetylene compounds shows Delta n^0.43 at Lambda = 1.06 micrometers. A major drawback of the diacetylene compounds is their inadequate UV stability. To overcome this, we have modified the molecular structures and developed some new bistolane liquid crystals. Owing to its long molecular conjugation, the melting point of bistolane exceeds 140 deg C. High melting point implies to poor solubility while forming eutectic mixtures. To lower melting point, methyl and ethyl substitutions in the middle phenyl ring have been found effective. Some ethyl-substituted bistolanes are liquid crystals at room temperature. However, the viscosity of the ethyl bistolanes is increased. The methyl substitution represents a compromise between melting temperature and viscosity. Prof. Hsu's group has helped us synthesize dozens of cyano and fluoro bistolanes. The Delta n of the cyano bistolane was extrapolated to be 0.53 at Lambda = 0.633 micrometers and T = 22 deg C.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 02, 2001
- Accession Number
- ADA392990
Entities
People
- Shin-Tson Wu
Organizations
- HRL Laboratories