First-principle design and analysis of photonic-crystal planar waveguides and linear arrays with ultra-large single-mode areas

In this paper, novel single-mode (SM) photonic-crystal planar waveguides (PCPW) and linear arrays have been proposed and systematically studied. Advanced elliptic features are embedded into the basic photonic crystal design to differentiate leakage losses between the fundamental and high-order modes, which ensures SM propagation property. Furthermore, linear arrays of PCPWs are proposed to generate fundamental supermodes with ultra-large SM areas. Our study shows that these multi-unit PCPW linear arrays can perform equivalently as ultra-wide planar waveguides that are possible to achieve SM modal areas as large as over 10,000 μm² with preferable Gaussian-shaped far-field intensity patterns, readily supporting optical powers well over 100 kW. The presented study can be inspiring for designs of single-waveguide solid-state lasers and amplifiers to generate laser beams of extremely high power and high brightness.