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Publication Metadata only 10-NJ multipass-cavity femtosecond CR3+: LiCAF laser pumped by low-power single-mode diodes(Optical Society of America, 2009) Kärtner, Franz X.; Fujimoto, James G.; Demirbaş, Ümit; Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851We report on the generation of 9.9-nJ, 95-fs pulses at a repetition rate of 9.58 MHz from a multipass-cavity Cr3+:LiCAF laser pumped by single-mode diodes with a total absorbed pump power of only 540 mW.Publication Metadata only 80-NJ multipass-cavity chirped-pulse Cr4+: forsterite laser(Optical Society of America, 2010) Fujimoto, James G.; Department of Physics; Sennaroğlu, Alphan; Çankaya, Hüseyin; Faculty Member; Researcher; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 23851; N/ABy using 8.5 W of incident pump power, we obtained 80-nJ, 5.5-ps pulses at 1260 nm with a spectral width of 17 nm from a multipass-cavity, chirped-pulse Cr4+:forsterite laser operated at 4.9-MHz repetition rate. © 2010 Optical Society of America.Publication Open Access A broken gauge approach to gravitational mass and charge(Springer, 2002) Tucker, R. W.; Department of Physics; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; 201358We argue that a spontaneous breakdown of local Weyl invariance offers a mechanism in which gravitational interactions contribute to the generation of particle masses and their electric charge. The theory is formulated in terms of a spacetime geometry whose natural connection has both dynamic torsion and non-metricity. Its structure illuminates the role of dynamic scales used to determine measurable aspects of particle interactions and it predicts an additional neutral vector boson with electroweak properties. © SISSA/ISAS 2002.Publication Open Access A narrow-band multi-resonant metamaterial in near-ir(Multidisciplinary Digital Publishing Institute (MDPI), 2020) Ali, Farhan; Department of Physics; Ramazanoğlu, Serap Aksu; Faculty Member; Department of Physics; College of Sciences; 243745We theoretically investigate a multi-resonant plasmonic metamaterial perfect absorber operating between 600 and 950 nm wavelengths. The presented device generates 100% absorption at two resonance wavelengths and delivers an ultra-narrow band (sub-20 nm) and high quality factor (Q = 44) resonance. The studied perfect absorber is a metal–insulator–metal configuration where a thin MgF2 spacer is sandwiched between an optically thick gold layer and uniformly patterned gold circular nanodisc antennas. The localized and propagating nature of the plasmonic resonances are characterized and confirmed theoretically. The origin of the perfect absorption is investigated using the impedance matching and critical coupling phenomenon. We calculate the effective impedance of the perfect absorber and confirm the matching with the free space impedance. We also investigate the scattering properties of the top antenna layer and confirm the minimized reflection at resonance wavelengths by calculating the absorption and scattering cross sections. The excitation of plasmonic resonances boost the near-field intensity by three orders of magnitude which enhances the interaction between the metamaterial surface and the incident energy. The refractive index sensitivity of the perfect absorber could go as high as S = 500 nm/RIU. The presented optical characteristics make the proposed narrow-band multi-resonant perfect absorber a favorable platform for biosensing and contrast agent based bioimaging.Publication Open Access A new type of microphotoreactor with integrated optofluidic waveguide based on solid-air nanoporous aerogels(Royal Society of Chemistry (RSC), 2018) Jonas, Alexandr; Department of Chemistry; Department of Electrical and Electronics Engineering; Department of Physics; Özbakır, Yaprak; Erkey, Can; Kiraz, Alper; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Department of Electrical and Electronics Engineering; Department of Physics; College of Engineering; College of Sciences; N/A; 29633; 22542In this study, we developed a new type of microphotoreactor based on an optofluidic waveguide with aqueous liquid core fabricated inside a nanoporous aerogel. To this end, we synthesized a hydrophobic silica aerogel monolith with a density of 0.22 g cm(-3) and a low refractive index of 1.06 that-from the optical point of view-effectively behaves like solid air. Subsequently, we drilled an L-shaped channel within the monolith that confined both the aqueous core liquid and the guided light, the latter property arising due to total internal reflection of light from the liquid-aerogel interface. We characterized the efficiency of light guiding in liquid-filled channel and-using the light delivered by waveguiding-we carried out photochemical reactions in the channel filled with aqueous solutions of methylene blue dye. We demonstrated that methylene blue could be efficiently degraded in the optofluidic photoreactor, with conversion increasing with increasing power of the incident light. The presented optofluidic microphotoreactor represents a versatile platform employing light guiding concept of conventional optical fibres for performing photochemical reactions.Publication Open Access A nonminimally coupled, conformally extended Einstein-Maxwell theory of pp-waves(TÜBİTAK, 2020) Department of Physics; Dereli, Tekin; Şenikoğlu, Yorgo; Researcher; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; 201358; N/AA nonminimal coupling of Weyl curvatures to electromagnetic fields is considered in Brans-Dicke-Maxwell theory. The gravitational field equations are formulated in a Riemannian spacetime where the spacetime torsion is constrained to zero by the method of Lagrange multipliers in the language of exterior differential forms. The significance and ramifications of nonminimal couplings to gravity are examined in a pp-wave spacetime.Publication Metadata only Acousto-optic mode-locking of a Cr2+: ZnSe laser(Optica Publishing Group, 2000) Carrig, Timothy J.; Wagner, Gregory J.; Jeong, Jay Y.; Pollock, Clifford R.; Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851Acousto-optic mode-locking of a Cr2+:ZnSe laser that produces 4.4 psec duration, transform-limited, Gaussian shaped pulses is described. The laser outputs 82 mW of output power at an 81 MHz pulse repetition frequency.Publication Open Access Addendum to 'Unidirectionally invisible potentials as local building blocks of all scattering potentials'(American Physical Society (APS), 2014) Department of Mathematics; Department of Physics; Mostafazadeh, Ali; Faculty Member; Department of Mathematics; Department of Physics; College of Sciences; 4231In [Phys. Rev. A 90, 023833 (2014)], we offer a solution to the problem of constructing a scattering potential v(x) which possesses scattering properties of one's choice at an arbitrarily prescribed wave number. This solution involves expressing v(x) as the sum of n <= 6 finite-range unidirectionally invisible potentials. We improve this result by reducing the upper bound on n from 6 to 4. In particular, we show that we can construct v(x) as the sum of up to n = 3 finite-range unidirectionally invisible potentials, unless if it is required to be bidirectionally reflectionless.Publication Metadata only An LED-based super resolution GPU implemented structured illumination microscope(Spie-Int Soc Optical Engineering, 2020) Aydin, Musa; N/A; N/A; N/A; Department of Physics; Uysallı, Yiğit; Özgönül, Ekin; Morova, Berna; Kiraz, Alper; PhD Student; PhD Student; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; College of Sciences; N/A; N/A; N/A; 22542Fluorescence imaging of sub-cellular structures with sizes below the diffraction limit is vital in understanding cellular processes. Relying on exciting the sample with different illumination patterns and image processing for the elimination of background fluorescence, Structured Illumination Microscopy (SIM) provides imaging capability beyond diffraction limit using relatively simple optical setups. Here, we present a laser-free, DLP projector-based, and GPU-implemented SIM super resolution microscope. Sub-diffractive biological structures were imaged with a lateral resolution of similar to 150 nm. The microscopy system is LED-based and entirely home-built which enables customizable operation at a low cost.Publication Open Access An optofluidic FRET laser using aqueous quantum dots as donors(Society of Photo-optical Instrumentation Engineers (SPIE), 2016) Chen, Qiushu; Fan, Xudong; Department of Physics; Kiraz, Alper; Faculty Member; Department of Physics; College of Sciences; 22542The integration of optofluidic laser and FRET mechanism provides novel research frontiers, including sensitive biochemical analysis and novel photonic devices, such as on-chip coherent light sources and bio-tunable lasers. Here we investigated an optofluidic FRET laser using quantum dots (QDs) as FRET donors. We achieved lasing from Cy5 as the acceptor in the QD-Cy5 pair with excitation at 450 nm where Cy5 has negligible absorption by itself. The threshold was approximately 14 mu J/mm(2). The demonstrated capability of QDs as the donor in a FRET laser greatly improves the versatility of optofluidic laser operation due to the broad and large absorption cross section of QDs in the blue and UV spectral region. The excitation efficiency of the acceptor molecules through FRET channel was also analyzed, showing that the energy transfer rate and the non-radiative Auger recombination rate of QDs plays a significant role in FRET laser performance.