Robert W. Byren

All-dielectric subwavelength metasurface focusing lens

We have proposed, designed, manufactured and tested low loss dielectric micro-lenses for infrared (IR) radiation based on a dielectric metamaterial layer. This metamaterial layer was created by patterning a dielectric surface and etching to sub-micron depths. For a proof-of-concept lens demonstration, we have chosen a fine patterned array of nano-pillars with variable diameters. Gradient index (GRIN) properties were achieved by engineering the nano-pattern characteristics across the lens, so that the effective optical density of the dielectric metamaterial layer peaks around the lens center, and gradually drops at the lens periphery. A set of lens designs with reduced reflection and tailorable phase gradients have been developed and tested, demonstrating focal distances of a few hundred microns, beam area contraction ratio up to three, and insertion losses as low as 11%.

High-power Yb:YAG rod oscillators and amplifiers

We report 0.95 kW average output power from a single cw-diode pumped Yb:YAG power oscillator. The 3-mm diameter solid-state laser rod is side pumped by three sets of cw diode arrays each of which has an electrical-to-optical efficiency of up to 50%. Our phase-conjugate master oscillator, power-amp architecture will incorporate this pump cavity as one of the power amplifiers for multi-kW average power, good beam quality laser applications.

High-Power Side-Diode-Pumped Yb:YAG Laser

We report 600 W quasi-cw output power from a side-diode-pumped Yb:YAG rod power oscillator and 225 W average power in preliminary cw diode-pumping experiments.