Optical properties of semiconductor nano-structures and photoactive yellow protein
AuthorLyngnes, Ove, 1967-
AdvisorGibbs, Hyatt M.
MetadataShow full item record
PublisherThe University of Arizona.
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AbstractThe linear and nonlinear optical properties of semiconductor nano-structures and photoactive yellow protein (PYP) have been studied in this work. The reflection and transmission properties of multiple InₓGa₍₁₋ₓ₎As quantum well (QW) samples are first presented. Constructive interference in the reflection from the QWs is observed when the QWs are spaced by λ/2 (λ = exciton absorption peak wavelength) and destructive interference when the spacing is λ/4. The nonlinear transmission of fs pulses through a QW sample is also studied. A broadening of the exciton transition with negligible loss of oscillator strength is observed. Semiconductor microcavity samples with embedded quantum wells exhibiting normal mode coupling (NMC) are studied both in the linear and nonlinear regime, with ultrafast time resolution using upconversion. A decrease in the modulation depth of the NMC oscillations and reflection dips with increasing incident photon flux without a change of NMC oscillation period and splitting are observed, consistent with a bleaching of the exciton transition without loss of oscillator strength. The effective mass of multiple QW samples measured from the slope of Landau Levels of the QWs in magnetic field is measured for both photoluminescence (PL) and absorption spectra. For some samples, the absorption spectra show an effective mass consistent with the electron-hole effective mass while the PL spectra show an effective mass consistent with just the electron. This is explained by hole localization on monolayer island fluctuations on the QW/barrier interfaces. The magnetic field is also used to measure Faraday rotation in semiconductor microcavities exhibiting NMC. A resonant Faraday rotation of 3° degrees is observed in reflection. Finally the nonlinear one-photon and two-photon absorption (TPA) properties of PYP are investigated. One-photon excitation results in a complete bleaching of the absorption peak. No TPA is observed, but an upper limit of 3.5·10⁻⁵²cm⁴ s molecule⁻¹photon⁻¹ for the TPA cross section is found.
Degree ProgramGraduate College