Page 44 - Undergraduate Research Opportunities Program Proceedings 2017-18

School of Science
Department of Physics

manufacturing process as well as from the transmittance and reflectance analyses I will illustrate the current state of the
project, compare the results to last semester’s and suggest further steps to be taken to achieve better results.

Supervisor: TAM Wing Yim / PHYS
Student: CHAN Yi / PHYS Course: UROP1000, Summer
LI Wing Shun / PHYS-IRE UROP2100, Fall
UROP3100, Summer

This project aims to find out the change in optical activities in laser dye in its ground state and excited state. A cylindrical
cell was used to store the dye and trap an air bubble for interferometry analysis. Several factors affecting the thickness
of gap, which is an important parameter in interferometry, were studied. Tests regarding the volume of bubbles and the
leakage of the cell were carried out. Lastly, a laser pumping test was tried however the data analyzed cannot draw a
conclusion.

Supervisor: TAM Wing Yim / PHYS
Student: NGAI Tsz Ue / PHYS Course: UROP1100, Fall
UROP2100, Sping

Phase change on reflection is important optical property to be considered for designing metamaterial surface. Following
Yung’s et al. idea of using continuum source for phase measurement, this project aims to measure the reflection phase
change using supercontinuum laser and FP interferometer mounted on a rotation table. This setup is able to measure
the dependence of phase change on the incidence angle within beam diameter of 2 mm. A glass-air-100 nm Au etalon
was tested with clear interference pattern emerged. The constructive interference peaks were analyzed by the two-
beam model and the air-gap spacing and the reflection phase of the etalon. This setup is also able to measure the
transmission phase change for transparent materials.

Controlling Confinement Effect of Polymer Dynamics

Supervisor: TSUI Ophelia K. C. / PHYS
Student: CHOW Man To / PHYS-IRE Course: UROP1100, Fall
UROP2100, Sping

The glass transition temperatures, Tg, of random copolymer thin films containing poly(4-tert-butylstyrene) (P4TBS) and
poly(4-acetoxystyrene) (P4AS), with two compositions, 65.6 mol% P4TBS (P4TBS-66%) and 47.5 mol% P4TBS (P4TBS-
48%), were investigated against those of pure P4TBS and P4AS thin films. The Tg of P4TBS decreases with decreasing film
thickness while that of P4AS increases with decreasing film thickness. We thus expect that the Tg vs film thickness, h,
curves (Tg curves) to follow the order of pure P4AS, P4TBS-48%, P4TBS-66% and pure P4TBS from highest to lowest Tg
values for thin enough films. However, no discernible difference could be found between the Tg curves of P4TBS-66%
and pure P4TBS. Separately, we observed that the breadth of the glass transition of both copolymer films decreases with
decreasing film thickness, suggesting that P4TBS may dominate the dynamics of the Tg of the P4TBS-co-P4AS copolymer
films.

Supervisor: TSUI Ophelia K. C. / PHYS
Student: WANG Tong / PHYS-IRE Course: UROP1000, Summer

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