Browsing by Author "Gokkavas, Mutlu"

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    AlxGa1-xN-based avalanche photodiodes with high reproducible avalanche gain
    (AIP Publishing LLC, 2007) Tut, Turgut; Gokkavas, Mutlu; Inal, Ayşe; Özbay, Ekmel
    The authors report high performance solar-blind photodetectors with reproducible avalanche gain as high as 1560 under ultraviolet illumination. The solar-blind photodetectors have a sharp cutoff around 276 nm. The dark currents of the 40 μm diameter devices are measured to be lower than 8 fA for bias voltages up to 20 V. The responsivity of the photodetectors is 0.13 A/W at 272 nm under 20 V reverse bias. The thermally limited detectivity is calculated as D* = 1.4 × 1014 cm Hz1/2 W-1 for a 40 μm diameter device.
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    ItemOpen Access
    Reduction in temperature-dependent fiber-optic gyroscope bias drift by using multifunctional integrated optical chip fabricated on pre-annealed linbo3
    (MDPI AG, 2024-12-11) Karagoz, Ercan; Aşık, Fatma Yasemin; Gokkavas, Mutlu; Akbaş, Erkut Emin; Yertutanol, Aylin; Ozbay, Ekmel; Ozcan, Sadan
    The refractive index change obtained after annealed proton exchange (APE) in lithium niobate (LiNbO3) crystals depends on both the proton exchange process carried out in hot acid and the structure of the crystals. In devices produced by the APE method, dislocations and lattice defects within the crystal structure are considered to be primary contributors to refractive index discontinuities and waveguide instability. In this study, the effects of pre-annealing LiNbO3 crystals at 500 degrees C on multifunctional integrated optical chips (MIOCs) were investigated through interferometric fiber-optic gyroscope (IFOG) system-level tests. It was observed that the pre-annealing process resulted in an improvement in the optical throughput of MIOCs (from %34 to %51) and the temperature-dependent bias drift stability of the IFOG (from 0.031-0.038 degrees/h to 0.012-0.019 degrees/h). The angle random walk (ARW) was measured as 0.0056 deg/root h.