M. Selim Unlu

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We report the fabrication and testing of a GaAs-based high-speed resonant cavity enhanced (RCE) Schottky photodiode. The top-illuminated RCE detector is constructed by integrating a Schottky contact, a thin absorption region (In/sub 0.08/Ga/sub 0.92/As) and a distributed AlAs-GaAs Bragg mirror. The Schottky contact metal serves as a high-reflectivity top(More)
In this letter, we report the first resonant-cavity-enhanced single-photon avalanche diode (RCE SPAD) fabricated on a reflecting silicon-on-insulator (SOI) substrate. The substrate incorporates a two-period distributed Bragg reflector fabricated using a commercially available double-SOI process. The RCE SPAD detectors have peak photon detection efficiencies(More)
High-speed Schottky photodiodes suffer from low efficiency mainly due to the thin absorption layers and the semitransparent Schottky-contact metals. We have designed, fabricated and characterized high-speed and high-efficiency AlGaAs-GaAs-based Schottky photodiodes using transparent indium-tin-oxide Schottky contact material and resonant cavity enhanced(More)
We present nanometer scale axial localization of fluorescent markers to probe subcellular structures using self-interference based fluorescence microscopy. We show probing the membrane topography of a gram-negative bacterium, Shigella flexneri, and discuss further applications.
In this study, we report on the utilization of layered substrates for increased performance of fluorescent-based detection schemes. Through optimization of layer thicknesses, we demonstrate that enhancement with respect to commonly used microscope slides is achieved for the collected fluorescence signal.
The strong electroabsorption modulation possible using the quantum-confined Stark effect in Ge/SiGe quantum wells provides the working mechanism for efficient, CMOS-compatible photonic integrated modulators. We describe such a device employing a surface-normal asymmetric Fabry-Perot design.
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