Browsing by Author "Makey, Ghaith"

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Open Access
1.06μm-1.35μm coherent pulse generation by a synchronously-pumped phosphosilicate Raman fiber laser
(OSA, 2017) Elahi, Parviz; Makey, Ghaith; Turnalı, Ahmet; Tokel, Onur; İlday, Fatih Ömer
Summary form only given. Rare-earth-doped fiber lasers are attractive for microscopy and imaging applications and have developed over the past decades rapidly. They are unable to cover near-infra-red region entirely and therefore Raman and parametric process are promising for producing new wavelengths which are out of emission band of the current fiber lasers. Here, we demonstrate a synchronously-pumped Raman laser system for producing coherent signals spanning from 1.06 μm to 1.35 μm. The laser system comprises a passively-mode-locked oscillator, two stages of amplifier and a phosphosilicate Raman oscillator. The schematic of experimental setup is shown in Fig. 1(a). A mode locked oscillator operating at 37 MHz is using as a seed source. The output pulse duration and central wavelength are 6 ps and 1065 nm, respectively. 6 mW output from oscillator is launched to pre amplifier comprises 85-cm long Yb 401-PM pumped by a single mode diode through a PM wavelength division multiplexer (WDM). The power amplifier consists of a 3.5-m long Yb 1200-DC-PM with 6 μm core diameter and 125 μm cladding diameter pumped by a temperature stabilized, high power multimode diode laser via a multimode pump-signal combiner (MPC). A 30/70 coupler is employed for delivering pump signal at 1060 nm to the Raman oscillator comprises 4.2-m long ph-doped fiber. To synchronize pump and Raman and achieve coherent pulses, we adjust the length of cavity by a precise translation stage. By using proper filter inside the Raman cavity, different wavelengths are achieved.
Open Access
Applying the principle of orthogonality of high dimensional random vectors to obtain high-density, large-volume 3D holographic display
(OSA, 2018) Makey, Ghaith; Yavuz, Özgün; Kesim, Denizhan Koray; Turnalı, Ahmet; Elahi, Parviz; Toumi, J.; El-Daher, M. S.; Ilday, Serim; Tokel, Onur; İlday, F. Ömer
The efforts toward truly 3D displays are far from exploiting the full potential of holography. Here, we apply the principle of orthogonality of high dimensional random vectors to obtain unprecedented dense, large volume holograms.
Open Access
Breaking crosstalk limits to dynamic holography using orthogonality of high-dimensional random vectors
(Nature Publishing Group, 2019) Makey, Ghaith; Yavuz, Özgün; Kesim, Denizhan K.; Turnalı, Ahmet; Elahi, Parviz; İlday, Serim; Tokel, Onur; İlday, F. Ömer
Holography is the most promising route to true-to-life three-dimensional (3D) projections, but the incorporation of complex images with full depth control remains elusive. Digitally synthesized holograms1,2,3,4,5,6,7, which do not require real objects to create a hologram, offer the possibility of dynamic projection of 3D video8,9. Despite extensive efforts aimed at 3D holographic projection10,11,12,13,14,15,16,17, however, the available methods remain limited to creating images on a few planes10,11,12, over a narrow depth of field13,14 or with low resolution15,16,17. Truly 3D holography also requires full depth control and dynamic projection capabilities, which are hampered by high crosstalk9,18. The fundamental difficulty is in storing all the information necessary to depict a complex 3D image in the 2D form of a hologram without letting projections at different depths contaminate each other. Here, we solve this problem by pre-shaping the wavefronts to locally reduce Fresnel diffraction to Fourier holography, which allows the inclusion of random phase for each depth without altering the image projection at that particular depth, but eliminates crosstalk due to the near-orthogonality of large-dimensional random vectors. We demonstrate Fresnel holograms that form on-axis with full depth control without any crosstalk, producing large-volume, high-density, dynamic 3D projections with 1,000 image planes simultaneously, improving the state of the art12,17 for the number of simultaneously created planes by two orders of magnitude. Although our proof-of-principle experiments use spatial light modulators, our solution is applicable to all types of holographic media.
Open Access
Buried waveguides written deep inside silicon
(OSA, 2017) Turnalı, Ahmet; Tokel, Onur; Kesim, Denizhan Koray; Makey, Ghaith; Elahi, Parviz; İlday, Fatih Ömer
Summary form only given. Silicon waveguides are widely used as optical interconnects and they are particularly important for Si-photonics. Si-based devices, along with other optical elements, are entirely fabricated on the top surface of Si wafers. However, further integration of photonic and electronic devices in the same chip requires a new approach. One alternative is to utilize the bulk of the wafer for fabricating photonic elements. Recently, we reported a direct-laser-writing method that exploits nonlinear interactions and can generate subsurface modifications inside silicon without damaging the surface. Using this method, we fabricated several functional optical elements including gratings, lenses, and holograms. In this work, we demonstrate optical waveguides entirely embedded in Si.
Open Access
Computer-generated holograms embedded in bulk silicon with nonlinear laser lithography
(IEEE, 2016) Turnalı, Ahmet; Tokel, Onur; Makey, Ghaith; Pavlov, Ihor; İlday, Fatih Ömer
Recently, we have showed a direct laser writing method to form subsurface structures inside silicon by exploiting nonlinear interactions. Here, we demonstrate utilization of this phenomenon to create computer-generated holograms buried in silicon.
Open Access
Dynamic evolution of hyperuniformity in a driven dissipative colloidal system
(Institute of Physics Publishing Ltd., 2021-06-18) Nizam, Seleme Ümmü; Makey, Ghaith; Barbier, Michaël; Kahraman., S.S; Demir, Esin; Shafigh, Ehsan Eslami; Galioğlu, Sezin; Vahabli, D.; Hüsnügil, Sercan; Güneş, Muhammed H.; Yelesti, Efe; İlday, Serim
Hyperuniformity is evolving to become a unifying concept that can help classify and characterize equilibrium and nonequilibrium states of matter. Therefore, understanding the extent of hyperuniformity in dissipative systems is critical. Here, we study the dynamic evolution of hyperuniformity in a driven dissipative colloidal system. We experimentally show and numerically verify that the hyperuniformity of a colloidal crystal is robust against various lattice imperfections and environmental perturbations. This robustness even manifests during crystal disassembly as the system switches between strong (class I), logarithmic (class II), weak (class III), and non-hyperuniform states. To aid analyses, we developed a comprehensive computational toolbox, enabling real-time characterization of hyperuniformity in real- and reciprocal-spaces together with the evolution of several order metric features, and measurements showing the effect of external perturbations on the spatiotemporal distribution of the particles. Our findings provide a new framework to understand the basic principles that drive a dissipative system to a hyperuniform state.
Open Access
Holograms deep inside Silicon
(Optical Society of America, 2016) Makey, Ghaith; Tokel, Onur; Turnalı, Ahmet; Pavlov, Ihor; Elahi, Parviz; Yavuz, Ozg ¨ un; İlday, F. Ömer
Through the Nonlinear Laser Lithography method, we demonstrate the first computer generated holograms fabricated deep inside Silicon. Fourier and Fresnel holograms are fabricated buried inside Si wafers, and a generation algorithm is developed for hologram fabrication. © OSA 2016.
Open Access
Intracavity optical trapping of microscopic particles in a ring-cavity fiber laser
(Nature Publishing Group, 2019-06) Kalantarifard, Fatemeh; Elahi, Parviz; Makey, Ghaith; İlday, F. Ömer; Volpe, Giovanni; Maragò, O. M.
Standard optical tweezers rely on optical forces arising when a focused laser beam interacts with a microscopic particle: scattering forces, pushing the particle along the beam direction, and gradient forces, attracting it towards the high-intensity focal spot. Importantly, the incoming laser beam is not affected by the particle position because the particle is outside the laser cavity. Here, we demonstrate that intracavity nonlinear feedback forces emerge when the particle is placed inside the optical cavity, resulting in orders-of-magnitude higher confinement along the three axes per unit laser intensity on the sample. This scheme allows trapping at very low numerical apertures and reduces the laser intensity to which the particle is exposed by two orders of magnitude compared to a standard 3D optical tweezers. These results are highly relevant for many applications requiring manipulation of samples that are subject to photodamage, such as in biophysics and nanosciences.
Open Access
Optical trapping of microparticles and yeast cells at ultra-low intensity by intracavity nonlinear feedback forces
(SPIE, 2020) Kalantarifard, A.; Elahi, P.; Makey, Ghaith; Ünlü, B.; Marago, O. M.; İlday, Fatih Ömer; Volpe, G.; Dholakia, K.; Spalding, G. C.
In standard optical tweezers optical forces arise from the interaction of a tightly focused laser beam with a microscopic particle. The particle is always outside the laser cavity and the incoming beam is not affected by the particle position. Here we describe an optical trapping scheme inside the cavity of a fiber laser where the laser operation is nonlinearly influenced by the displacement of trapped particle and there is a coupling between laser operation to the motion of the trapped particle and this can dramatically enhances optical tweezers action and gives rise to nonlinear feedback forces. This scheme operates using an aspheric lens at low numerical aperture (NA=0.125), NIR wavelength (λ = 1030 nm), and very low average power which results in about two orders of magnitude reduction in exposure to laser intensity compared to standard optical tweezers. Ultra-low intensity at our wavelength can grant a safe, temperature-controlled environment, away from surfaces for microfuidics manipulation of biosamples that are sensitive to light intensity. As the main advantage of our approach and highly relevant application, we observed that we can trap single yeast cells at a very low power, corresponding to an intensity of 0.036 mW μm-2, that is more than a tenfold less intensity than standard techniques reported in the literature.
Open Access
Optical waveguides written deep inside silicon by femtosecond laser
(OSA, 2017) Pavlov, Ihor; Tokel, Onur; Pavlova, S.; Kadan, V.; Makey, Ghaith; Turnalı, Ahmet; Çolakoğlu, T.; Yavuz, O.; İlday, Fatih Ömer
Summary form only given. Photonic devices that can guide, transfer or modulate light are highly desired in electronics and integrated silicon photonics. Through the nonlinear processes taking place during ultrafast laser-material interaction, laser light can impart permanent refractive index change in the bulk of materials, and thus enables the fabrication of different optical elements inside the material. However, due to strong multi-photon absorption of Si resulting delocalization of the light by free carriers induced plasma defocusing, the subsurface Si modification with femtosecond laser was not realized so far [1, 2]. Here, we demonstrate optical waveguides written deep inside silicon with a 1.5-μm high repetition rate femtosecond laser. Due to pulse-to-pulse heat accumulation for high repetition rate laser, additional thermal lensing prevents delocalization of the light around focal point, allowing the modification. The laser with 2-μJ pulse energy, 350-fs pulse width, operating at 250 kHz focused in Si produces permanent modifications. The position of the focal point inside of the sample is accurately controlled with pumpprobe imaging during processing. Optical waveguides of ~20-μm diameter, and up to 5.5-mm elongation are fabricated by translating the beam focal position along the optical axis. The waveguides are characterized with a 1.5-μm continuous-wave laser, through optical shadow-graphy (Fig. 1 a-b, e) and direct light coupling (Fig.1 c-d, f). The measured refractive index change obtained by quantitative shadow-graphy is ~6×10 -4 . The numerical aperture of the waveguide measured from decoupled light is 0.05.
Open Access
Rich complex behaviour of self-assembled nanoparticles far from equilibrium
(Nature Publishing Group, 2017) İlday, Serim; Makey, Ghaith; Akgüç, Gürsoy Bozkurt; Yavuz, Özgün; Tokel, Onur; Pavlovi, İhor; Gülseren, Oğuz; İlday, Faruk Ömer
A profoundly fundamental question at the interface between physics and biology remains open: what are the minimum requirements for emergence of complex behaviour from nonliving systems? Here, we address this question and report complex behaviour of tens to thousands of colloidal nanoparticles in a system designed to be as plain as possible: the system is driven far from equilibrium by ultrafast laser pulses that create spatiotemporal temperature gradients, inducing Marangoni flow that drags particles towards aggregation; strong Brownian motion, used as source of fluctuations, opposes aggregation. Nonlinear feedback mechanisms naturally arise between flow, aggregate and Brownian motion, allowing fast external control with minimal intervention. Consequently, complex behaviour, analogous to those seen in living organisms, emerges, whereby aggregates can self-sustain, self-regulate, self-replicate, self-heal and can be transferred from one location to another, all within seconds. Aggregates can comprise only one pattern or bifurcated patterns can coexist, compete, endure or perish.
Open Access
Self-dissimilarity, irreversibility and robustness in mode-locked fiber oscillators
(OSA, 2018) Makey, Ghaith; Teamir, Tesfay; İlday, Serim; İlday, F. Ömer
We introduce self-dissimilarity as measure of phase space complexity and predictor of robustness against perturbations. As nonlinearity increases, phase space becomes a random fractal, just before critical transitions. Measurements confirm powerlaw dependence over 7 decades.
Open Access
Two-photon excitation of quantum dots in 3D via stacked fresnel hologram algorithm
(OSA, 2017) Kesim, Denizhan Koray; Makey, Ghaith; Yavuz, Özgün; Tokel, Onur; İlday, Fatih Ömer
Quantum dots are engineered to have nanometers dimensions. The ability to specify the diameter and the material of the quantum dots allow us tune the absorption and emission properties. This results in extensive capabilities for imaging and display applications. Further, with two photon absorption and high peak power laser they can be excited at any point in 3D locally.
Open Access
Universality of dissipative self-assembly from quantum dots to human cells
(Nature Research, 2020) Makey, Ghaith; Galioğlu, Sezin; Ghaffari, Roujin; Engin, E. D.; Yıldırım, Gökhan; Yavuz, Özgün; Bektaş, O.; Nizam, Ü. S.; Akbulut, Özge; Şahin, Özgür; Güngör, Kıvanç; Dede, Didem; Demir, Hilmi Volkan; İlday, Fatih Ömer; İlday, Serim
An important goal of self-assembly research is to develop a general methodology applicable to almost any material, from the smallest to the largest scales, whereby qualitatively identical results are obtained independently of initial conditions, size, shape and function of the constituents. Here, we introduce a dissipative self-assembly methodology demonstrated on a diverse spectrum of materials, from simple, passive, identical quantum dots (a few hundred atoms) that experience extreme Brownian motion, to complex, active, non-identical human cells (~1017 atoms) with sophisticated internal dynamics. Autocatalytic growth curves of the self-assembled aggregates are shown to scale identically, and interface fluctuations of growing aggregates obey the universal Tracy–Widom law. Example applications for nanoscience and biotechnology are further provided.