Novel devices with photosensitive elements

Ethan I. L. Jull; Helen F. Gleeson

doi:10.1117/12.2515807

1 March 2019 Novel devices with photosensitive elements

Ethan I. L. Jull, Helen F. Gleeson

Proceedings Volume 10941, Emerging Liquid Crystal Technologies XIV; 109410C (2019) https://doi.org/10.1117/12.2515807
Event: SPIE OPTO, 2019, San Francisco, California, United States

Abstract

Liquid Crystal (LC) devices with photosensitive elements have incredible scope for creating unique photo-induced optical devices. The use of azobenzene based materials, which undergo a trans-cis isomerisation when irradiated with light of a specific wavelength, is firmly established in LC research. The trans conformation is an elongated rod-like shape, similar to LC mesogens, whilst the cis conformation is closer to a spherical (bent) shape, disrupting to the LC order. When these materials are doped into LC materials they are able to produce light induced responses, and therefore their application to photo-switchable optics and devices is undeniable. In this research paper the light induced order modification, rather than light induced reorientation, is utilized to produce an all-optical switchable laser protection device. Upon irradiation of an azo-doped LC system with a continuous, low power (0.5 mW), laser threat (λ=405 nm) the transcis photoisomerisation process is triggered. This results in the trans-cis conformal shape change, lowering of the LC order, and causing the system to switch from the LC nematic phase (transmitting between crossed polarisers) to the isotropic liquid phase (blocking/dark between crossed polarisers). The optical properties of the azo-doped LC materials have been characterized and the response time dependence on azo-dopant concentration, system temperature, and laser threat intensity is thoroughly investigated.

Conference Presentation

Citation Download Citation

Ethan I. L. Jull and Helen F. Gleeson "Novel devices with photosensitive elements", Proc. SPIE 10941, Emerging Liquid Crystal Technologies XIV, 109410C (1 March 2019); https://doi.org/10.1117/12.2515807

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