Volume Bragg lasers based on high efficiency diffractive elements in photo-thermo-refractive glass

A resonator for a laser comprising:

• a photo-thermo-refractive (PTR) volume diffractive element having a high absolute diffraction efficiency to provide angular selectivity and spectral selectivity;
• and
• a collimating optics between the laser and the volume diffractive element for divergence of a laser radiation emitted from a gain medium of the laser, wherein said emitted radiation is directed toward said TPR volume diffractive element to provide control of at least one of a spectral and an angular parameter of the laser radiation;
• wherein a transverse mode grating to provide said angular selectivity, wherein said transverse mode grating provides a significant difference in losses for the transverse mode grating with adjacent numbers and said collimator provides divergence of said radiation;
• wherein a reflecting volume Bragg grating to provide said spectral selectivity, wherein said longitudinal mode grating is selected to provide significant difference in losses for longitudinal mode gratings with adjacent numbers and said collimating lens equalizes divergence of the laser beam along an orthogonal direction.