Abstract:We report the fabrication of high-Q polymeric microdisks on silicon via direct laser writing utilizing two-photon absorption induced polymerization. The quality factors of the passive cavities are above 10 6 in the 1300 nm wavelength region. The flexible three-dimensional (3D) lithography method allows for the fabrication of different cavity thicknesses on the same substrate, useful for rapid prototyping of active and passive optical microcavities. Microdisk lasers are realized by doping the resist with dye, resulting in laser emission at visible wavelengths. ©2011 Optical Society of America

We report on the fabrication of high-Q microresonators made of low-loss, thermoplastic polymer poly(methyl methacrylate) (PMMA) directly processed on a silicon substrate. Using this polymer-on-silicon material in combination with a thermal reflow step enables cavities of conical geometry with an ultrasmooth surface. The cavity Q factor of these PMMA resonators is above 2×106 in the 1300 nm wavelength range. Finite element simulations show the existence of a variety of “whispering gallery” modes in these resonators explaining the complexity of the measured transmission spectra.

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We report on the measurement of the absolute external luminescence quantum efficiency of various ZnO samples using a miniature integrating sphere fitted into a cryostat. Even the absolute luminescence quantum efficiencies per spectral interval are directly accessible. Measurements have been carried out on high quality bulk samples and different commercially available ZnO powders from 8K up to room temperature. Activated processes lead to an overall decrease in the efficiency with temperature. All efficiencies are considerably below unity, making the identification of the luminescence decay time with the radiative life time very questionable.