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%.
We have produced 5 mJ, 13 ns pulses using a very large-mode-area rectangular fiber containing a high-aspect-ratio core with dimensions of ~30 μm×580 μm. The rectangular fiber design retains a thin ...cladding dimension ~0.5 mm, which is compatible with a compact coiled package. We have developed a theoretical model that achieves good agreement with the experimental data. This model indicates that an optimized fiber design can be scaled to pulse energies of several tens of millijoules. We also discuss a strategy for maintaining good beam quality in both transverse dimensions of this fiber.
We have demonstrated stable operation of a 2-kW Yb:YAG phase-conjugate master oscillator power amplifier (PC-MOPA) laser system with a loop phase-conjugate mirror (LPCM). This is the first ...demonstration of a continuous wave (CW)-input LPCM MOPA operating at a power greater than 1 kW with a nearly diffraction-limited output beam. The single-pass beam quality incident on the LPCM varied with the specific operating conditions, but it was typically ~ 20 times diffraction-limited (XDL). The measured beam quality with an MOPA output power of 1.65 kW was 1.3 XDL.
All-dielectric metasurface focusing lens West, Paul R.; Stewart, James L.; Kildishev, Alexander V. ...
2014 Conference on Lasers and Electro-Optics (CLEO) - Laser Science to Photonic Applications,
2014-June
Conference Proceeding
Dielectric metamaterial layers are lossless, and exhibit relatively high transmission efficiencies (contrary to plasmonic metasurfaces). Subwavelength dielectric lenses have been developed - ...demonstrating beam area contraction ratio of three, and insertion losses of 11%.
Combined tests of tungsten mock-ups with thermocyclic test in the electron beam facility with the load up to 50 MW/m² and subsequent irradiation with steady-state plasma load up to 1 MW/m² in PLM ...device have been carried out to simulate a material degradation under loads expected in a fusion reactor. Cracks of 1–5 microns and more have been formed on the surface of the tungsten during e-beam test. Melted layer observed in the area of e-beam hot spot load. Plasma load led to a formation of nanostructured layers on the surface.
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