Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy.However,the diversity of their application is limited by the covered spectral bandwidth.In...Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy.However,the diversity of their application is limited by the covered spectral bandwidth.In particular,the upper frequency limit of photoconductive emitters-the most widespread technique in THz spectroscopy-reaches only up to 7 THz in the regular transmission mode due to absorption by infrared-active optical phonons.Here,we present ultrabroadband(extending up to 70 THz)THz emission from an Au-implanted Ge emitter that is compatible with mode-locked fibre lasers operating at wavelengths of 1.1 and 1.55μm with pulse repetition rates of 10 and 20 MHz,respectively.This result opens up the possibility for the development of compact THz photonic devices operating up to multi-THz frequencies that are compatible with Si CMOS technology.展开更多
We demonstrate third harmonic generation in plasmonic antennas consisting of highly doped germanium grown on silicon substrates and designed to be resonant in the mid-infrared frequency range that is inaccessible with...We demonstrate third harmonic generation in plasmonic antennas consisting of highly doped germanium grown on silicon substrates and designed to be resonant in the mid-infrared frequency range that is inaccessible with conventional nonlinear plasmonic materials.Owing to the near-field enhancement,the result is an ultrafast,subdiffraction,coherent light source with a wavelength tunable between 3 and 5μm,and ideally overlapping with the fingerprint region of molecular vibrations.To observe the nonlinearity in this challenging spectral window,a highpower femtosecond laser system equipped with parametric frequency conversion in combination with an all-reflective confocal microscope setup is employed.We demonstrate spatially resolved maps of the linear scattering cross section and the nonlinear emission of single isolated antenna structures.A clear third-order power dependence as well as mid-infrared emission spectra prove the nonlinear nature of the light emission.Simulations support the observed resonance length of the double-rod antenna and demonstrate that the field enhancement inside the antenna material is responsible for the nonlinear frequency mixing.展开更多
基金The support by R.Bottger and the Ion Beam Center(IBC)at HZDR is gratefully acknowledged.
文摘Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy.However,the diversity of their application is limited by the covered spectral bandwidth.In particular,the upper frequency limit of photoconductive emitters-the most widespread technique in THz spectroscopy-reaches only up to 7 THz in the regular transmission mode due to absorption by infrared-active optical phonons.Here,we present ultrabroadband(extending up to 70 THz)THz emission from an Au-implanted Ge emitter that is compatible with mode-locked fibre lasers operating at wavelengths of 1.1 and 1.55μm with pulse repetition rates of 10 and 20 MHz,respectively.This result opens up the possibility for the development of compact THz photonic devices operating up to multi-THz frequencies that are compatible with Si CMOS technology.
基金support from the European Commission via the Marie Curie Carrier Integration Grant and the Seventh Framework Programme under Grant No.613055the Deutsche Forschungsgemeinschaft through the Emmy Noether programme and the EPSRC under Grant No.EP/N003225/1。
文摘We demonstrate third harmonic generation in plasmonic antennas consisting of highly doped germanium grown on silicon substrates and designed to be resonant in the mid-infrared frequency range that is inaccessible with conventional nonlinear plasmonic materials.Owing to the near-field enhancement,the result is an ultrafast,subdiffraction,coherent light source with a wavelength tunable between 3 and 5μm,and ideally overlapping with the fingerprint region of molecular vibrations.To observe the nonlinearity in this challenging spectral window,a highpower femtosecond laser system equipped with parametric frequency conversion in combination with an all-reflective confocal microscope setup is employed.We demonstrate spatially resolved maps of the linear scattering cross section and the nonlinear emission of single isolated antenna structures.A clear third-order power dependence as well as mid-infrared emission spectra prove the nonlinear nature of the light emission.Simulations support the observed resonance length of the double-rod antenna and demonstrate that the field enhancement inside the antenna material is responsible for the nonlinear frequency mixing.
