Adaptive modally addressed liquid crystal lenses

An adaptive lens, which has variable focus and is rapidly controllable with simple low-power electronics, has numerous applications in optical telecommunications devices, 3D display systems, miniature cameras and adaptive optics. The University of Durham is developing a range of adaptive liquid crystal lenses, and here we describe work on construction of modal liquid crystal lenses. This type of lens was first described by Naumov [1] and further developed by others [24]. In this system, a spatially varying and circularly symmetric voltage profile can be generated across a liquid-crystal cell, generating a lens-like refractive index profile. Such devices are simple in design, and do not require a pixellated structure. The shape and focussing power of the lens can be controlled by the variation of applied electric field and frequency. Results show adaptive lenses operating at optical wavelengths with continuously variable focal lengths from infinity to 70 cm. Switching speeds are of the order of 1 second between focal positions. Manufacturing methods of our adaptive lenses are presented, together with the latest results to the performance of these devices.

Numerical simulation of dicke superradiance in a semiconductor laser device

This paper reports a theoretical model for Dicke Superradiance in semiconductor laser devices. Simulations agree well with previously-observed superradiance properties and are used to optimize driving conditions and device geometry. © OSA/ANIC/IPR/Sensors/SL/SOF/SPPCom/2011.

Sub-kHz RF electrical linewidth from a 10GHz passively mode-locked quantum-dot laser diode

A packaged 10GHz monolithic two-section quantum-dot mode-locked laser is presented, with record narrow 500Hz RF electrical linewidth for passive mode-locking. Single sideband noise spectra show 147fs integrated timing jitter over the 4MHz-80MHz frequency range. © 2009 Optical Society of America.