Longitudinal and transversal optical antenna plasmon resonance spectra from two-photon laser excitation

We record two-photon luminescence (TPL) emission spectra for two-arm nanoantennas of width 20 nm, height 30 nm and variable arm length of 25 to 65 nm, with a 20 nm gap between the arms, fabricated on an indium tin oxide (ITO) covered glass substrate using electron beam lithography and gold evaporation.