【学术报告】Prof. Dr. Andrey Iljin----A view on LC’s prospects for holography applications

发布者:邢晓东发布时间:2018-11-23浏览次数:13

学术报告

报告题目: A view on LC’s prospects for holography applications

报告人: Prof. Dr. Andrey Iljin

Institute of Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine

时间:2018112310:00

地点:泰达应用物理研究院四楼报告厅

邀请人张心正教授

  

Liquid crystals (LC), owing to their large birefringence and strong responsiveness to external fields appear nearly omnipresent in modern optoelectronic and photonic technologies and devices. Almost all known nonlinear optical phenomena have been observed in LC media due to their extraordinarily large optical nonlinearities that span over multiple time scales in a spectral range from the visible to infrared and beyond.

  

Light induced realignment of the LC director with the associated reorientation of the optical axis has been the principal mechanism engaged in the vast majority of nonlinear optical experiments. The elastic forces of LC medium, however, spread vastly outside the illuminated region making the nonlinear optical response substantially nonlocal and concealing the recorded optical information. Wherein, as far as holography needs are concerned, a strict one to one correspondence between the light intensity and refractive index modulation is required.

  

Mechanisms of a local light stimulated modulation of the LC order parameter bring in the changes of the refractive indices of the LC medium, which are accounted for in a generalized Light-Induced Order Modification (LIOM) model. The model appears to be in a good agreement with and explains well the experimentally observed large optical nonlinearities and extremely fast as for the LC system recording times as well as a very high resolution (<1 μm) opening new possibilities for volume grating recording.

  

Despite being strictly local in material response the LIOM mechanism nevertheless implies a fine tuning of a phase shift between an interference pattern and a refractive index grating it stimulated. Such a photorefractive non-locality could be widely used for the amplification of laser beams and optical images, creation of phase delay lines, in beam steering, phase conjugation, shaping of pulses, etc.


 

欢迎各位老师和同学届时参加!