An optical amplifier system comprising: a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars, the periodic distance being measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars, wherein the diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%; a diffractive optic disposed along the optical path, wherein the diffractive optic comprises a photo-thermo-refractive glass member, wherein the diffractive optic is obtained by: providing a partially transmissive optical element having a predetermined grayscale intensity pattern thereon; providing a transparent optical element; directing UV radiation through the partially transmissive optical element to impinge on the transparent optical element; exposing a predetermined portion of the transparent optical element to the UV radiation; and thermally treating the transparent optical element to produce the diffractive homogenizer characterized by a continuously varying index of refraction profile as a function of position within the transparent optical element; and an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance, wherein a second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%, wherein the photo-thermo-refractive glass member comprises a continuous variation in the index of refraction and wherein the photo-thermo-refractive glass member is substantially free of sinusoidal grating structures. a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars, the periodic distance being measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars, wherein the diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%; a diffractive optic disposed along the optical path, wherein the diffractive optic comprises a photo-thermo-refractive glass member, wherein the diffractive optic is obtained by: providing a partially transmissive optical element having a predetermined grayscale intensity pattern thereon; providing a transparent optical element; directing UV radiation through the partially transmissive optical element to impinge on the transparent optical element; exposing a predetermined portion of the transparent optical element to the UV radiation; and thermally treating the transparent optical element to produce the diffractive homogenizer characterized by a continuously varying index of refraction profile as a function of position within the transparent optical element; and an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance, wherein a second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%, wherein the photo-thermo-refractive glass member comprises a continuous variation in the index of refraction and wherein the photo-thermo-refractive glass member is substantially free of sinusoidal grating structures. providing a partially transmissive optical element having a predetermined grayscale intensity pattern thereon; providing a transparent optical element; directing UV radiation through the partially transmissive optical element to impinge on the transparent optical element; exposing a predetermined portion of the transparent optical element to the UV radiation; and thermally treating the transparent optical element to produce the diffractive homogenizer characterized by a continuously varying index of refraction profile as a function of position within the transparent optical element; and an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance, wherein a second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%, wherein the photo-thermo-refractive glass member comprises a continuous variation in the index of refraction and wherein the photo-thermo-refractive glass member is substantially free of sinusoidal grating structures.