Realization of 193 nm DUV laser through direct frequency doubling with GaN-based UVA laser diode and ABF crystal

• First demonstration of 193 nm DUV laser via direct frequency doubling using a GaN-based UVA laser diode and ABF crystal. • ABF crystal enables phase-matching SHG down to 158 nm, making 193 nm achievable. • GaN-based UVA laser diode with 4.6 W continuous-wave output power serves as the fundamental source. • Direct frequency doubling offers a more efficient and compact alternative to ArF excimer lasers for DUV lithography.