The BragGrate™ technology of high-efficiency volume Bragg gratings (VBG’s) was developed at the Center for Research and Education in Optics and Lasers (CREOL) at the University of Central Florida. It is based on a permanent refractive index change in a special multi-component silicate glass (BragGlass™) after exposure to UV radiation followed by a thermal development. The BragGlass™ enables fabrication of phase volume diffractive gratings with absolute diffraction efficiency exceeding 99% and thermal stability of 400°C. It has a laser damage threshold of 40 J/cm2 for 8 ns pulses, and tolerance to CW laser radiation in the near IR region at least up to several tens of kilowatts per square centimeter. Such volume Bragg gratings provide narrow spectral selectivity down to 20 pm and narrow angular selectivity down to 100 μrad. These elements have low losses and can be used for a variety of applications in optoelectronics, analytical, and defense industries.
BragGrate™ (or BG™) is a trademark of OptiGrate for volume Bragg gratings (VBG) produced by a refractive index modulation in the volume of a photosensitive BragGlass™. Depending on the diffraction angle and orientation of a grating in the plate, one can distinguish several types of VBG diffractive optical elements.