Highly Efficient 3D Nonlinear Photonic Crystals in Ferroelectrics

Nonlinear photonic crystals (NPCs) with spatially modulated second-order nonlinear coefficients are indispensable in optics and modern photonics. To access full degrees of freedom the generation control coherent light at new frequencies, three dimensional (3D) NPCs have been recently fabricated employing femtosecond laser writing technique ferroelectric crystals. However, interaction efficiencies 3D so far rather low, which has a major barrier to further development. Here, fabrication challenges large-scale overcome realize more than four orders magnitude efficiency improvement over previously reported With second harmonic vortex beam as an example, measured conversion high 2.9 × 10−6 W−1 (femtosecond pulse-pumped) 1.2 10−5 (continuous-wave-pumped) comparable those 1D or 2D NPCs. A general approach structural simplification relax challenge truly complex structures without sacrificing predesigned functions is also presented. This realization efficient interactions paves way for their novel applications photonics quantum including orbital angular momentum multiplexing high-dimensional entangled source.