High power Yb:YAG/YAG composite thin-disk laser

Summary form only given. Our goal in the initial phase of this project is to prove the applicability of the several innovations used in our approach to building a diode-pumped, solid-state laser of scaleable, high average power with beam quality. Recent experimental results give us confidence in our scalability arguments. To affirm the viability of the concept, the first step is to demonstrate 300 W of sustained output. Shown are the diode arrays, hollow lens ducts, and output coupler, in addition to a blow-up of the Yb:YAG/YAG composite laser disk situated on the cooler (soldered with indium). This is the equipment we are testing. One of the crucial advantages of the thin-disk design is that the thermal gradients are aligned with the beam propagation direction, so that they do not impart significant wavefront distortion onto the light field. To first order, the thin-disk laser geometry mitigates the effects of dn/dT and stress-optic effects. A second order effect remains, relating to the pump uniformity. Deformations are the main source of wavefront error in a thin-disk however, because the "stiffness" of a beam is proportional to the cube of its thickness a major advantage of our approach to thin-disk lasers is therefore the diffusion bonded undoped cap, which rises to a constant temperature. The cap becomes a "stiffness" member for the HiBriTE laser-disk, keeping the deformations to a minimum. Thermo-mechanical calculations will be presented. Another advantage provided by the diffusion bonded cap is that it allows for side-pumping with laser diodes. The cap layer also provides a larger volume that is used to dilute spontaneous emission greatly diminishing the adverse impact of amplified spontaneous emission. We are using a telescopic resonator to enable laser output with high beam quality from our prototype.