Controlling Laser Modes with Intra-cavity Optical Meta-surfaces

We present the incorporation of geometric phase metasurfaces (GPMs) into a laser cavity in order to achieve a topologically spin-controlled output beams and intra-cavity modes. Despite recent progress, many GPM elements, still suffer from limited light matter interaction strengths, and consequently low efficiencies. To overcome this limitation, we incorporated GPM elements inside laser cavities, thereby yielding nearly perfect efficiencies. Specifically, the shared aperture metasurfaces were placed as output couplers in a modified degenerate cavity laser [1] so as to obtain unique coherent and partially coherent multiple harmonic scalar vortex laser beams. Utilizing interleaved metasurfaces, we also generated vectorial vortices by coherently superposing of scalar vortices with opposite topological charges and spin states. We also introduce a GPM into a laser in order to achieve a topologically controlled intra-cavity mode [2]. By utilizing the geometric phase we found a spin-enabled self-consistent cavity solution of a Nd:YAG laser with a silicon-based metasurface. Specifically, we designed an efficient dielectric GPM based on silicon nanoantennas operating in transmission mode. Using this solution we generated a laser mode possessing helicity-controlled orbital angular momentum

The implementation of the spin-orbit interaction mechanism within a laser-cavity provided the route to control the topology of the output and intra-cavity mode in a spin-dependent manner. The incorporation of the metasurface platforms into a laser cavity opens a pathway to novel types of nanophotonic functionalities and enhanced light-matter interactions, offering exciting new opportunities for light manipulation.

References:

1. "Spin-controlled twisted laser beams: intra-cavity multi-tasking geometric phase metasurfaces", R. Chriki, E. Maguid, C. Tradonsky, V. Kleiner, A. A. Friesem, N. Davidson and E. Hasman, Opt. Exp. 26, 905 (2018).

2. "Topologically controlled intra-cavity laser modes based on Pancharatnam-Berry phase ", E. Maguid, R. Chriki, M. Yannai, V. Kleiner, E. Hasman A. A. Friesem, and N. Davidson ACS Nano 5, 1817 (2018).