Laser beam control and fine spectral filtering by volume Bragg gratings in PTR glass

This presentation is a survey of recent achievements in lasers with resonators which include volume Bragg gratings – volume Bragg lasers. The technology of diffractive optical elements (volume Bragg gratings, VBGs) recorded in a photo-thermo-refractive (PTR) glass was developed at CREOL/The College of Optics and Photonics, University of Central Florida and licensed to OptiGrate Corporation. These elements enable dramatic improvement of parameters of different types of lasers and spectral analyzers demonstrated by a number of different research and industrial groups. The use of narrow band gratings for spectral selection enabled new effective approaches for Raman spectrometers, for spectral imaging and for narrow band spectral analyzers. The use of reflecting Bragg gratings as output couplers in external resonators for semiconductor diodes, bars and stacks provided efficient spectral locking with power penalty below 5%. This application enabled pumping of lasers with extremely narrow absorption bands, such as cryogenic solid state and low pressure gas alkali lasers. Bragg mirrors enabled spectral narrowing of solid state and fiber lasers down to few picometers. Effective transverse mode selection in semiconductor and solid state lasers resulted in dramatic increase of their spatial brightness. Chirped Bragg gratings with variable period were used for stretching and compression short laser pulses resulting in decrease of size of these devices by an order of magnitude. Volume Bragg gratings were successfully used for coherent and spectral combining of laser beams. Phase locking of diode and fiber lasers was demonstrated. Record spectral brightness was achieved by spectral combining of fiber lasers.