LASER SYSTEM WITH MECHANICALLY-ROBUST MONOLITHIC FUSED PLANAR WAVEGUIDE (PWG) STRUCTURE

An apparatus includes a PWG having a core region and a cladding layer. The amplifier is configured to receive pump light. The core region is configured to amplify an input beam using energy from the pump light to generate an amplified output beam. The apparatus also includes a cooling fluid configured to cool the core region. The cooling fluid has a lower refractive index than the core region and the cladding layer in order to support guiding of the input beam and pump light within the amplifier. The amplifier also includes first and second endcaps attached to opposite faces of the core region and cladding layer. The core region, cladding layer, and endcaps collectively form a monolithic fused structure. Each endcap has a major outer surface that is larger in area than a combined area of the faces of the core region and cladding layer to which the endcap is attached.