Investigations on tunabilities of pretilt angle and distributed feedback laser based on liquid crystal cells incorporating with micro- and nano-grooves of polymer

  • 游 凱宇

學生論文: Doctoral Thesis

摘要

This thesis entitled “Investigations on the tunability of pretilt angle and distributed feedback laser based on liquid crystal cells incorporated with micro- and nano-grooves of polymer ” examines the tunability of liquid crystal (LC)-based optical devices with a grooved structure The following two topics are discussed (1) Controllable pretilt angle of LCs with the formation of microgrooves This work investigates the controllability of the pretilt angle of LCs in a cell with an initial vertical alignment through microgrooves induced by the holographic fast-writing method By changing the writing time or intensity of the pumped beam the microgrooves with various surface modulations can form and provide distinct planar anchoring strength for the LCs The pretilt angle of the LCs can be controlled from 18 3° to 89° The writing time of the microgrooves takes less than 25 s which is a two-fold reduction in the time taken in previous investigations using other photoalignment methods (2) Thermally tunable LC distributed feedback laser based on a polymer grating with nanogrooves fabricated by nanoimprint lithography (NIL) This work demonstrates a thermally tunable dye-doped liquid crystal (DDLC) distributed feedback (DFB) laser based on a polymer grating The surface emitting the DDLC DFB laser is supported by the second-order Bragg grating with nanogrooves with periodicity of 360 nm and pre-fabricated by UV NIL The lasing wavelength of the DFB laser can be tuned from 625 1 nm to 606 35 nm if the temperature increases from 10 °C to 50 °C The tunability of the laser is attributable to the temperature-sensitive feature in the effective refractive index of the LCs
獎項日期2014 八月 25
原文English
監督員Chia-Rong Lee (Supervisor)

引用此文

Investigations on tunabilities of pretilt angle and distributed feedback laser based on liquid crystal cells incorporating with micro- and nano-grooves of polymer
凱宇, 游. (Author). 2014 八月 25

學生論文: Doctoral Thesis