Dynamic polarization flip in nanoripples on photoexcited Ti surface near its surface plasmon resonance

Both normal and abnormal sub-100-nanometer ripples (wavenumber ∼10  μm(-1)) were separately observed on Ti surfaces excited by linearly polarized IR femtosecond laser pulses at lower and higher fluences. Numerical modeling of dispersion curves for surface plasmon-polaritons on the photoexcited Ti surfaces demonstrates its surface plasmon resonance with the peak wavenumber ∼8  μm(-1) spectrally tuned by prompt surface optical response, prompt surface charging, and pre-oxidation, with normal/abnormal nanoripples appearing at its red/blue shoulders, respectively.