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Liquid Crystal Phase Modulators

Liquid Crystal Phase Modulators

There are three main aspects to our research on liquid crystal phase modulators:

  • design and characterisation of new optical phase modulators,
  • development of new characterisation techniques to assess optical phase modulation in soft materials, 
  • integration of optical phase modulators into optical systems (e.g., Lidar, beam-steering for optical communications).

Figure 1. 

For the first part, we have been working on the development of new optical phase modulators based upon the flexoelectro-optic effect in chiral nematic liquid crystals. When the liquid crystal layer is sandwiched between quarter-wave plates (Figure 1) we have demonstrated that it is possible to obtain full 2p phase modulation at switching frequencies greater than 1 kHz [1]. We have explored ways to reduce the initial bench-top configuration to an integrated device architecture by replacing the separate quarter-wave plates and mirrors with polymerised liquid crystal waveplates and reflective substrates (Figure 2) [2, 3]. This work has been carried out in collaboration with the group of Professor Georg Mehl at the University of Hull and Professor Tim Wilkinson at the University of Cambridge. In addition to reflective device geometries, which create the double-pass needed to achieve 2p phase modulation, we have also been carrying out research on transmissive device configurations by cascading liquid crystal devices, as shown in Figure 3 [4].

Figure 2. Integrated flexoelectro-optic phase modulator.

Figure 3. Transmissive flexoelectro-optic phase modulator configurations.

Publications

A Compact Full 2π Flexoelectro-Optic Liquid Crystal Phase Modulator

Xiuze Wang, Julian A. J. Fells, Yuping Shi, Taimoor Ali, Chris Welch, Georg H. Mehl, Timothy D. Wilkinson, Martin J. Booth, Stephen M. Morris, and Steve J. Elston Advanced Material Technologies 5, 2000589 (2020)

Millisecond optical phase modulation using multipass configurations with liquid crystal devices

Yihan Jin, Steve J. Elston, Julian A. J. Fells, Martin J. Booth, Chris Welch, Georg H. Mehl, and Stephen M. Morris Physical Review Applied 14, 024007 (2020)

Transmissive flexoelectro-optic liquid crystal optical phase modulator with 2π modulation

Xiuze Wang, Julian A. J. Fells, Taimoor Ali, Jia-De Lin,  Chris Welch, Georg H. Mehl, Timothy D. Wilkinson, Martin J. Booth, Stephen M. Morris, and Steve J. Elston AIP Advances 10, 055011 (2020)

Dynamic response of large tilt-angle flexoelectro-optic liquid crystal modulators

Julian A. J. Fells, Chris Welch, Wing C. Yip, Steve J. Elston, Martin J. Booth, Georg H. Mehl, Timothy D. Wilkinson, and Stephen M. Morris Opt. Express 27(11), 15184-15193 (2019) 

Fast and low loss flexoelectro-optic liquid crystal phase modulator with a chiral nematic reflector

Xiuze Wang, Julian A. J. Fells, Wing C. Yip, Taimoor Ali, Jia-de Lin, Chris Welch, Georg H. Mehl, Martin J. Booth, Timothy D. Wilkinson, Stephen M. Morris & Steve J. Elston Scientific Reports 9, 7016 (2019)

Robust measurement of flexoelectro-optic switching with different surface alignments

John J. Sandford O’Neill, Julian A. J. Fells, Chris Welch, Georg Mehl, Wing C. Yip, Timothy D. Wilkinson, Martin J. Booth, Steve J. Elston, and Stephen M. Morris  Journal of Applied Physics 125, 093104 (2019)

Flexoelectro-optic liquid crystal analog phase-only modulator with 2π range and 1 kHz switching

Julian A.J. Fells, Xiuze Wang, Steve J. Elston, Chris Welch, Georg H. Mehl, Martin J. Booth, and Stephen M. Morris Optics Letters 43, 4362-4365 (2018)

Characterization of large tilt-angle flexoelectro-optic switching in chiral nematic liquid crystal devices

Xiuze Wang, Julian A. J. Fells, Chris Welch, Maria-Gabriela Tamba, Georg H. Mehl, Stephen M. Morris, Steve J. Elston Liquid Crystals 46, 408-414 (2018)

Time-resolved retardance and optic-axis angle measurement system for characterization of flexoelectro-optic liquid crystal and other birefringent devices

Julian A. J. Fells, Steve J. Elston, Martin J. Booth, and Stephen M. Morris Optics Express 26(5), 6126-6142 (2018)

Solvent-induced self-assembly of uniform lying helix alignment of the cholesteric liquid crystal phase for the flexoelectro-optic   effect

S. Bolis, C. C. Tartan, J. Beeckman, P. Kockaert, S. J. Elston and S. M. Morris  Liquid Crystals 45, 774-782 (2018)