Browsing by Subject "Semiconducting indium gallium arsenide"

Now showing 1 - 4 of 4

Open Access
Category-selective top-down modulation in the fusiform face area of the human brain during visual search
(IEEE, 2017) Dar, Salman Ul Hassan; Çukur, Tolga
Several regions in the ventral-temporal cortex of the human brain are thought to have representations of specific categories of objects. Furthermore, a distributed network of frontal and parietal brain regions is implicated in attentional control. It is assumed that during visual search, attention-control regions send top-down signals to the target category-selective areas to bias the processing in favour of the attended object category. However, little is known about such causal interactions during naturalistic visual search. Here we assess the influence of attention-control brain regions on a well-known face selective area fusiform face area (FFA) during natural visual search using Granger causality analysis. Our results indicate that attending to humans enhances the influence of attention-control regions on the fusiform face area.
Open Access
Electrically-reconfigurable integrated photonic switches
(IEEE, 2004) Fidaner, O.; Demir, Hilmi Volkan; Sabnis V.A.; Harris Jr. J.S.; Miller, D.A.B.; Zheng J.-F.
We report remotely electrically reconfigurable photonic switches that intimately integrate waveguide electroabsorption modulators with surface-normal photodiodes, avoiding conventional electronics. These switches exhibit full C-band wavelength conversion at 5 Gb/s and are remotely reconfigurable within tens of nanoseconds.
Open Access
High-performance 1.55 μm resonant cavity enhanced photodetector
(IEEE, 2002) Kimukin, İbrahim; Bıyıklı, Necmi; Özbay, Ekmel
A high speed and high efficiency resonant cavity enhanced InGaAs based photodetector was demonstrated. A peak quantum efficiency of 66% was measured along with 31 GHz bandwidth with the device. The photoresponse was found to be linear upto 6 mW optical power, where the device 5 mA photocurrent.
Open Access
High-speed InGaAs based resonant cavity enhanced p-i-n photodiodes
(IEEE, 2001) Kimukin, İbrahim; Bıyıklı, Necmi; Özbay, Ekmel
High-speed InGaAs based resonant cavity enhanced photodiodes were discussed. The responses of the photodiodes was measured under high incident optical powers. Bandwidth-efficiency (BWE) product was used to measure the performance of the photodiode. Transfer matrix method was used to design the epilayer structure and to simulate the optical properties of the photodiode. Photo response measurements were carried out in 1450 nm to 1700 nm range using a tungsten-halogen projection lamp as the light source and a single pass monochromator. The deconvolved Fourier transform of the data was found to have a bandwidth of 31 GHz under conditions of 40 GHz limit.