Laser Pulse Compression
A 91cm x 42cm MLD grating for laser
Gratings for pulse compression have very demading
requirements. They must have a 26 to 40 layer multilayer dielectric reflector
coating, the devices must operate in a high vacuum, flatness requirements
are severe, and laser damage thresholds must be high in the short pulse
(0.5 to 10 ps) regime. In these conditions, coating stress must be carefully
considered since too much compressive stress will deform the substrate
and too much tensile stress will cause coating and substrate crazing.
PGL has developed a low stress coating for
silica substrates in cooperation with Osaka University and Okamoto Optics
LTD in Yokahama, Japan. High flatness gratings are much easier to produce
on silica than other high thermal expansion glasses. The coating process
uses ion-assisted deposition to induce the correct amount of film stress
to produce a net-zero stress on the device in vacuum. Damage-thresholds
of this coating have demonstrated values as high as the best conventional
e-beam deposited coatings.
Pulse compressor schematic for the LLE/University
of Rochester OMEGA EP
Precision Textured Surfaces
formation of uniform and repeatable patterns on a nanostructure scale
can be produced with the SBIL process. Such patterns on surfaces requiring
precise periodic structures of various shapes and geometry can be established
directly on substrates as masters and be used to make replicated nanostructered
surfaces.Further texturing can be done using ion-etching techniques.
200 nm Gratings For
LCD Display Wire-Grid Polarizers Wire grid polarizers require a fine array
of grating lines etched into silica. PGL has produced these structure
with periods as small as 200 nm. We are now working on devices that have
even smaller periods and methods to apply these patterns to cylindrical
substrates for replication.