The nonlinear optical properties of one-dimensional all-solid-state photonic-crystal microcavities (MCs) are ex-perimentally studied by second- harmonic generation (SHG) spectroscopy in both the frequency and the wave- vector domains. The studied single and coupled MCs are formed by the alternating of mesoporous silicon layers of different porosities. When the fundamental radiation is in resonance with the MC mode the second-harmonic intensity is enhanced by a factor of approximately 10 2 . The resonant SHG response is compared with the off-resonance response, as the fundamental wavelength is outside the photonic bandgap. The split-ting of the modes of two identical coupled MCs is observed in the wave-vector domain spectrum of enhanced SHG. The SHG enhancement is attributed to the combined effects of the spatial localization of the funda-mental field in the MC spacer and the fulfillment of the phase-matching conditions. The confinement of the resonant fundamental field is probed directly at the MC cleavage by a scanning near-field optical microscope. The role of the phase matching that is associated with the giant effective dispersion in the spectral vicinity of the MC mode is deduced from a comparison with the SHG peaks at both edges of the photonic bandgap.
Giant optical second- harmonic generation in single and coupled microcavities formed from one-dimensional photonic crystal
2002
Abstract
The nonlinear optical properties of one-dimensional all-solid-state photonic-crystal microcavities (MCs) are ex-perimentally studied by second- harmonic generation (SHG) spectroscopy in both the frequency and the wave- vector domains. The studied single and coupled MCs are formed by the alternating of mesoporous silicon layers of different porosities. When the fundamental radiation is in resonance with the MC mode the second-harmonic intensity is enhanced by a factor of approximately 10 2 . The resonant SHG response is compared with the off-resonance response, as the fundamental wavelength is outside the photonic bandgap. The split-ting of the modes of two identical coupled MCs is observed in the wave-vector domain spectrum of enhanced SHG. The SHG enhancement is attributed to the combined effects of the spatial localization of the funda-mental field in the MC spacer and the fulfillment of the phase-matching conditions. The confinement of the resonant fundamental field is probed directly at the MC cleavage by a scanning near-field optical microscope. The role of the phase matching that is associated with the giant effective dispersion in the spectral vicinity of the MC mode is deduced from a comparison with the SHG peaks at both edges of the photonic bandgap.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
