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Publication Metadata only Few-shot learning for segmentation of yeast cell microscopy images(IEEE, 2021) Alkan, Muhammet; Kiraz, Berna; Eren, Furkan; N/A; Department of Physics; Uysallı, Yiğit; Kiraz, Alper; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542Cell segmentation from microscopic images can be performed using deep neural networks or image processing techniques. In addition to their inherent difficulties, these techniques come together with the requirement of feeding the neural network with a large number of image samples in order to obtain a good result. However, this is not sustainable in terms of collecting and labeling microscopic images and represents a costly and time-consuming solution for every new microscopic image and cell type. Instead, fine-tuning can be employed by taking advantage of the adaptation ability of a model trained using meta-learning algorithms. In this way, while more general and better results can be obtained with fewer samples, the training process does not start from scratch for each new cell type or data set. In this article, microscopic images of yeast cells were recorded and analyzed using Reptile algorithm. After fine-tuning with a small number of samples, an average success rate of 81 % IoU (Intersection over Union) was obtained on the test pictures in addition to the model accuracy reaching up to 87%.Publication Metadata only GaInNAs microspheres for wavelength division multiplexing(Institute of Electrical and Electronics Engineers (IEEE), 2003) Bilici, T; Işçi, S; Kurt, A.; Department of Physics; Serpengüzel, Ali; Faculty Member; Department of Physics; College of Sciences; 27855The GaInNAs range of compounds is suitable for optoelectronic device applications in 1.3 and 1.55 mum lasers, because of the large conduction band discontinuity resulting in good electron confinement and improved temperature characteristics. GaInNAs is suited to wavelength division multiplexing (WDM) applications in high-speed optical Communication networks. Since WDM techniques are available for steady-state traffic, there is a need for an all-optical packet-switching layer at the end of the optical to electronic conversion domain, which consists of all-optical gates, such as semiconductor optical amplifiers, channel dropping filters, interferometers, resonant cavity enhanced photodetectors, and optical random access memory elements. In these planar lightwave circuits, GaInNAs microspheres with their morphology-dependent resonances, can be used as compact optical filtering elements. The spectral filtering characteristics of GaInNAs microspheres are analysed by calculating the elastic scattering spectra optimised for both transverse electric and transverse magnetic resonance modes at the optical communication wavelengths of 1.3 and 1.55 mum.Publication Metadata only Lightwave circuit elements based on microsphere resonators and meandering waveguides(IEEE, 2016) Department of Physics; Serpengüzel, Ali; Faculty Member; Department of Physics; College of Sciences; 27855The microspheres, with their high quality factor morphology dependent resonances (MDRs), are ideal optical resonators for three dimensional volumetric lightwave circuits. The microsphere leads itself to various lightwave circuit element applications such as channel dropping filters [1], tunable filters [2], optical modulators [3], and dynamic tuners [4]. So far we have realized these applications using silicon spheres coupled with optical fiber half couplers manufactured from single mode optical fibers. Biosensing might also be realized with these silicon microsphere resonators [5]. On the integrated optics side, we recently introduced distributed feedback (DFB) meandering waveguides as novel integrated optical elements [6]. We analyzed silicon DFB meandering waveguides, which can exhibit a variety of spectral responses such as coupled resonator induced transparency (CRIT) filter, Fano resonator, hitless filter, Lorentzian filter, Rabi splitter, self-coupled optical waveguide (SCOW), and tunable power divider. In this talk, we will focus on the properties of silicon spherical resonators and distributed feedback (DFB) meandering waveguides and their potential as lightwave components.Publication Metadata only Meandering waveguide distributed feedback lightwave circuits(IEEE-Inst Electrical Electronics Engineers Inc, 2015) Dağ, Ceren B.; Anıl, Mehmet A.; Department of Physics; Serpengüzel, Ali; Faculty Member; Department of Physics; College of Sciences; 27855Meandering waveguide distributed feedback structures are introduced as novel integrated photonic lightwave circuit elements, and analyzed in the frequency domain by the transfer matrix method. The directional coupling of the electromagnetic field occurs at the meander coupling points. The meandering loop mirror is the building block of all meandering waveguide-based lightwave circuit elements. The simplest uncoupled meandering distributed feedback structure exhibits Rabi splitting in the transmittance spectrum. The symmetric and antisymmetric coupledmeandering distributed feedback geometries can be utilized as bandpass, Fano, or Lorentzian filters or Rabi splitters. Meandering waveguide distributed feedback structures with a variety of spectral responses can be designed for a variety of lightwave circuit element functions.Publication Metadata only Mid-infrared elastic scattering from germanium microspheres(IEEE, 2016) N/A; N/A; N/A; N/A; Department of Physics; Zakwan, Muhammad; Bayer, Mustafa Mert; Anwar, Muhammad Sohail; Gökay, Ulaş Sabahattin; Serpengüzel, Ali; PhD Student; Master Student; Master Student; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; N/A; 27855Because of their ultrahigh optical nonlinearities and extremely broad transparency window, germanium microsphere resonators offer the potential for optical processing devices, especially in the mid-infrared (mid-IR) wavelengths. As a semiconductor material for microphotonics applications [1], germanium is particularly attractive owing to its large nonlinearity, high optical damage threshold compared with traditional nonlinear glass materials, and above all, its broad transparency window, extending from the near-IR into the mid-IR. Germanium based optical components have found numerous applications in imaging systems operating in the mid-IR wavelengths, where the principal natural greenhouse gases do not exhibit strong absorption. These applications include rapid sensing and diagnosis [2,] [3], industrial process controls, environmental monitors to hazardous chemical detection [4]. Germanium also is a good electromagnetic shielding material, an attribute that has become increasingly important for modern military applications, where other signals (within the millimeter and centimeter wavelength range) can be strong enough to interfere with nearby IR systems. Elastic light scattering from a germanium microsphere has already been observed in the near-IR [5]. Here, elastic light scattering from a germanium microsphere in the mid-IR region is numerically analyzed using generalized Lorenz-Mie theory (GLMT) [6]. Light interaction with microspheres of various materials is of much interest because of their photonic properties [7]. Germanium has a refractive index of 4, which is even higher than the refractive index of silicon (3.5) in the mid-IR region. The higher refractive index results in higher quality factor morphology dependent resonances (MDRs). A higher value of Q indicates a longer lifetime of the photons trapped inside the cavity and a narrower MDR. Here, the MDRs are observed numerically in the transverse magnetically (TM) and transverse electrically (TE) polarized 90° elastic scattering and 0° transmission for a 40 µm radius germanium microsphere in the mid-IR wavelengths ranging from 5.4 µm to 5.6 µm [8]. The mode spacing of approximately 41 nm between the resonances with the same radial mode order and consecutive polar mode number shows good correlation with the optical size of the germanium microsphere. The germanium microsphere with its high quality factor MDRs can be suitable for optical monitoring and sensing applications in the mid-IR, which require a high spectral resolution [9].