简介 |
An optical amplifier which includes an elongated slab of solid state lasing material, such as a rare earth doped yttrium-aluminum-garnet (YAG). In order to provide a relatively increased absorption length and thus a higher overall efficiency, the optical amplifier in accordance with the present invention incorporates end pumping in which the pumped light is coaligned with the amplified light resulting in relatively longer absorption lengths and higher overall efficiencies. The coaligned pumped sources are directed to lateral faces of the slab which include windows, formed from an insulating coating such as an anti-reflection coating, at the pump wavelength. In order to cause internal reflection of the pump beam along the lasing axis, the end faces are formed at about a 45 DEG angle relative to the longitudinal axis which causes the pumped light to be reflected within the slab co-axially with a amplified light. In order to confine the absorption of the pumped light to the center portion of the slab, the opposing end portions of the slab may be undoped while the center portion of the slab along the longitudinal axis is doped. Such a configuration provides relatively low residual thermal lensing with virtually no birefringence. |