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Kashma Rai
Advisor: Adam K. Fontecchio, Ph.D.
Abstract:
Confining liquid crystals (LCs) in diverse enclosures is extensively
used in emerging electro-optic technologies. LCs confined as nanodroplets,
in polymer matrix and arranged in periodic planes is known as
holographic polymer dispersed liquid crystals (HPDLCs). The refractive
index mismatch between the LC rich region and polymer rich region
creates a wavelength selective device. Applying an electric field
makes the hologram optically clear reversing the wavelength selective
property due to the reorientation of the LCs. This property is
excellent for application in optical communication for wavelength
de-multiplexing, display and state of the art integrated optics.
A key issue for broadband wavelength application is controllability
of the reflected wavelength of HPDLCs. We will present three types
of wavelength spanning devices using HPDLCs.
- First, variability of a single wavelength reflected by applying
hydrostatic pressure is presented. We have optimized this wavelength-reflecting
unit for pressure sensor application.
- In the second type of application, we assemble the HPDLCs in serial and parallel configuration reflecting a broad range of wavelength. This is employed in wavelength de-multiplexing and has potential application as a spectrometer.
- The third type of wavelength, selective HPDLC is a spatially continuous wavelength rejecting unit. This single broad wavelength reflecting HPDLC can be used in combination with stacked configuration discussed earlier.
To better understand and improve the electro optic properties we will present structural analysis data using microscopy and spectroscopy techniques and model the output waveform. To interpret the nano-scale structure scanning electron microscopy and to understand the LC behavior electron spin resonance spectroscopy is used. This has helped us to further fundamentally comprehend the LC polymer interaction and apply them as parameters for modeling multiple interacting wavelengths.
In summary we will discuss broadband wavelength interaction of HPDLCs and their microscopy and spectroscopy studies along with modeling their behavior.
Thursday, September 13th at 3 p.m.
Bossone 303
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