Browsing by Author "Saylan, Sueda"

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Open Access
Fourier-transform-only method for random phase shifting interferometry
(Institute of Physics Publishing Ltd., 2024-02-08) Saltık, Alperen; Saylan, Sueda; Tokel, Onur
An accurate and computationally simple phase shifting interferometry (PSI) method is developed to reconstruct phase maps without a priori knowledge of the phase shift. Previous methods developed for random PSI either do not address general sources of error or require complex iterative processes and increased computational time. Here we demonstrate a novel method that is able to extract the phase using only Fourier transform (FT). With spatial FT analysis, randomly phase-shifted data is reordered to allow performing temporal FT on the intensity, which is a function of the phase shift. Since the entire process, including order analysis and phase calculation, is based only on Fourier analysis, it is rapid, easy to implement, and addresses general sources of error. The method exhibits high performance in experiments containing random phase shifts. Moreover, simulations incorporating common experimental error sources such as random intensity noise, intensity harmonics, and phase shift errors demonstrate that the proposed method performs as good as or better than the state-of-the-art phase reconstruction techniques in terms of accuracy and time.
Open Access
HfO₂-based memristors for gamma-ray detection: an experimental and computational investigation
(IEEE, 2024-02-01) Saylan, Sueda; Hitt, George Wesley; Jaoude, Maguy Abi; Mohammad, Baker
In this work, we present a memristor with a thin film (~100-nm-thick) of a high-atomic-number material in a Cu/HfO2/$\text{p}^{+}$-Si stack to detect gamma-ray irradiation doses as low as ~30 mGy. The device leverages the unique properties of memristors, which exhibit a change in the resistance state upon applying an external electrical bias. This characteristic makes them well suited for dosimetry applications as the radiation exposure induces a change in the programming voltage ${V}_{{\text {SET}}}$. Our experiments reveal, on average, a 60% or more decrease in ${V}_{{\text {SET}}}$ in response to gamma-ray irradiation, covering a dose range of 30–850 mGy. These results highlight the potential of memristive sensing as a valuable tool for monitoring radiation exposure in space, safeguarding both individuals and electronics from its detrimental effects. In addition to the experimental findings, coupled radiation transport and radiation damage cascade simulations performed provide energy deposition, ionization, and defect distributions in the stack, yielding new insights into the device’s response to ionizing radiation. This combined approach aims at enhancing our understanding of the underlying processes and further optimizing the memristive sensing capability for radiation monitoring in space missions.
Open Access
High-efficiency multilevel volume diffraction gratings inside silicon
(American Chemical Society, 2023-11-08) Bütün, Mehmet; Saylan, Sueda; Sabet, Rana Asgari; Tokel, Onur
Silicon (Si)-based integrated photonics is considered to play a pivotal role in multiple emerging technologies, including telecommunications, quantum computing, and lab-chip systems. Diverse functionalities are either implemented on the wafer surface (“on-chip”) or recently within the wafer (“in-chip”) using laser lithography. However, the emerging depth degree of freedom has been exploited only for single-level devices in Si. Thus, monolithic and multilevel discrete functionality is missing within the bulk. Here, we report the creation of multilevel, high-efficiency diffraction gratings in Si using three-dimensional (3D) nonlinear laser lithography. To boost device performance within a given volume, we introduce the concept of effective field enhancement at half the Talbot distance, which exploits self-imaging onto discrete levels over an optical lattice. The novel approach enables multilevel gratings in Si with a record efficiency of 53%, measured at 1550 nm. Furthermore, we predict a diffraction efficiency approaching 100%, simply by increasing the number of levels. Such volumetric Si-photonic devices represent a significant advance toward 3D-integrated monolithic photonic chips.
Open Access
Multilevel diffraction gratings inside silicon towards spectral filtering
(SPIE - International Society for Optical Engineering, 2024-03-12) Bütün, Mehmet; Saylan, Sueda; Sabet, Rana Asgari; Tokel, Onur; Gemini, Laura; Kleinert, Jan; Miyaji, Godai
Silicon-based integrated photonics holds the promise of revolutionizing key technologies, such as telecommunications, computing, and lab-on-chip systems. One can achieve diverse functionalities in two ways: on the wafer surface ("on-chip") or within its bulk ("in-chip"), the latter gaining recognition due to recent advancements in laser lithography. Until recently, 3D in-chip laser writing has only been utilized for single-level devices, leaving a vast potential for monolithic and multilevel functionality within silicon untapped. In our previous research, we successfully designed and fabricated multilevel, high-efficiency diffraction gratings in silicon using nanosecond laser pulses. Their high performance stemmed from effective field enhancement at Talbot self-imaging planes. Our current work takes a theoretical approach, investigating how varying the grating period affects the performance of in-chip multilevel gratings. We demonstrate that the previously achieved 95% diffraction efficiency at a 1550 nm wavelength is also attainable with a reduced period of 3 μm. This smaller period is predicted to allow for spectral filtering, nearly equivalent to commercially available filters in terms of Full Width at Half Maximum (FWHM). Our findings underscore the potential of volumetric Si photonics and mark a significant step towards realizing 3D-integrated monolithic chips.