Enhanced laser pulse confinement in a photoconductive terahertz emitter through near-field sapphire-fiber microlens

Near-field laser pulse confinement via specific sapphire-fiber microlens in a large-area photoconductive terahertz (THz) emitter is experimentally verified. We demonstrate that the proposed sapphire-fiber microlens provides a 5-fold increase in emitted THz power, contributing to +6.5 dB in the signal-to-noise ratio and preserving the 2.5 THz spectral bandwidth.