Jeffrey T. Cheung

Dual frequency liquid crystal devices for infrared electro-optical applications

A dual frequency liquid crystal (DFLC) can be field-driven towards its unperturbed state, which dramatically reduces the overall electro-optical response time. DFLC materials with sub-millisecond switching speed are being used in infrared electro-optical devices at wavelengths up to 3 microns. The performance of devices such as tunable half-wave plates and optical phased arrays in agile beam steering devices, and wavefront controllers for adaptive optics are described. Device issues discussed include drive schemes, field of view, reflective direct drive backplane, infrared-transparent conductors, and antireflection coatings.

Pulsed Laser Deposition

Publisher Summary This chapter provides an overview of pulsed layer deposition (PLD) technology. It uses a high-energy pulsed laser as an external power source to ablate the source or target material. An important capability of PLD is the deposition of films in a reactive environment. Gas inlets are usually located just behind the vacuum window through which the laser beam transmits. This serves the dual purpose of introducing reactive gas and preventing condensation of evaporants on the window, which can reduce its optical transmission. The flexibility of PLD has brought out many system modifications. Most of them are designed to activate reactive gas to achieve better stoichiometry and lower growth temperature. Oxide films are the most logical material of choice for PLD, especially “simple oxides” referring to those containing only one type of cation. To be successful, PLD must compete against E-beam deposition and sputtering, in particular radio frequency magnetron sputtering.