Margaret Normand & Rui Zhang
Wed 28 Sep 2016, 13:00 - 14:00
Roger Land Building, Seminar Room G:02

If you have a question about this talk, please contact: Jonathan Terry (jgt)

Image for IMNS Seminar Series: Liquid Crystal Lasers and NEMS resonators

Pizza will be served at 13:00 and the presentations will start at 13:15

Talk 1:   MAGS NORMAND - Spinning liquid crystal tuneable laser prototype system for biomedical microscopy applications

Liquid crystal lasers have many advantages over traditional coherent light sources: their self-organising chiral nanostructure provides a simple and inexpensive tuneable resonant cavity and the wide available range of soluble organic dyes provide a broad and continuous tuning range across the visible spectrum and beyond. They are efficient and can be tailored to emit highly customisable light fields, including multiple simultaneous polychromatic emissions. They can even be painted or printed onto surfaces. However, limitations in the maximum stable average power (typically < 1 mW) have previously restricted their practical applications. Power is limited principally by repetition rate; typically < 200 Hz. Higher repetition rates lead to triplet state generation, optical fatigue, and a subsequent reduction in lasing efficiency and stability. In this talk I will discuss new advances in spinning liquid crystal lasers, which enable stable high repetition rate lasing (> 5 kHz) and a corresponding increase in average power. I will also report on the development of a portable, high-performance, liquid crystal laser prototype system that is being developed to demonstrate new capabilities in advanced biomedical microscopy techniques.

Talk 2:    RUI ZHANG - Two-dimensional semiconducting MoS2 and WSe2 based nanoelectromechanical resonators

Nano-electromechanical system (NEMS) based resonators offer the potential for extreme mass and force sensitivity, and have triggered intense interest in recent years. Two-dimensional (2D) materials are attractive for use in next generation NEMS devices due to their unique physical properties and flexibility in the fabrication of complex structures. This talk will describe the characterization of the mechanical properties of 2D WSe2 using nano-indentation experiments under an atomic force micro-scope (AFM). This will be followed by an introduction to the fabrication process of a suspended MoS2 transistor. A comparison of the electrical properties of suspended and supported 2D MoS2 devices will also be presented.