Electromechanical tuning of double-membrane Photonic Crystal Cavities
PL spectra and peak shift obtained by applying a gradually increasing voltage are shown in Fig. 1b. We report up to 7 nm mode shift when the applied bias reaches 8.6 V. By further increasing the voltage we observe the well-known pull-in phenomenon: the cantilever collapses on the substrate because electrostatic forces win over elastic forces. We attribute the need for high voltages to fabrication issues and imperfections such as the complete erosion of the p-doped InGaAsP layer in the photonic crystal region during the sacrificial layer etching. Further process optimization should result in PCCs with Q factors>10'000, electromechanically tunable over >30 nm.
Optomechanical wavelength and energy conversion in high- double-layer cavities of photonic crystal slabs.
We demonstrate that ultrasmall double-layer photonic-crystal-slab cavities exhibit a very high-Q value for a wide range of the layer spacing, which enables us to realize unique optomechanical coupling. By mechanically varying the separation, we can achieve extraordinarily large wavelength conversion. In addition, the light stored in the cavity can generate a large radiation force. We show that this system exhibits extremely high energy conversion efficiency between optical and mechanical energy, leading to a novel approach for the optomechanical control of light and matter.
Urban Identities and Catastrophe: Izmir and Salonica at the End of the Ottoman Empire*
Two huge fires dramatically influenced the urban development of Salonica and Izmir, in 1917 and in 1922, respectively. These catastrophes occurred after the Ottoman Empire fell, and Salonica and Izmir had shifted into new national contexts. The fires mainly destroyed the districts that were transformed during the late‐Ottoman period. These districts became the cosmopolitan façades of modern Izmir and Salonica. The post‐fires' tabula rasa provided an opportunity for Greek and Turkish politicians and European planners to change the urban identity of both cities. Moreover, the Lausanne Treaty of 1923 transformed their multicultural societies also. Reconstruction plans had been thought to de‐Ottomanize and remove the previous idea of the towns and their multiplicity, interpreting new cultural and nationalist feeling. Here, I emphasize how modernity was interpreted before and after the fires, and point out contradictions between ideological aspects of planning and how the first urban districts were built during the 1920s.