Teknofil Inc

İstanbul, Turkey

Teknofil Inc

İstanbul, Turkey
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Bilici T.,Bogazici University | Tabakoglu O.,Bogazici University | Kalaycioglu H.,Bilkent University | Kurt A.,Teknofil Ltd. | And 2 more authors.
2010 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC'10 | Year: 2010

Tm:YAP laser system at power levels up to 1.2 W at 1980 nm was established in both continuous-wave and modulated modes of operation. The fluence effect of the laser system for skin ablation was analyzed by histology analysis with Wistar rat skin tissues. Thermally altered length, thermally altered area, ablation area, and ablation depth parameters were measured on histology images of skin samples just after the laser operation and after four-day healing period. Continuous-wave mode of operation provided higher thermal effects on the skin samples. Lower fluence levels were found for efficient ablation effect. © 2010 IEEE.

Hocaoglu I.,Koç University | Cizmeciyan M.N.,Koç University | Erdem R.,Middle East Technical University | Ozen C.,Middle East Technical University | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

Colloidally stable and highly luminescent near-IR emitting Ag 2S quantum dots (NIRQDs) were prepared by a very simple aqueous method using 2-mercaptopropionic acid (2MPA) as a coating. Emission of Ag 2S-2MPA NIRQDs can be tuned between 780 and 950 nm. These NIRQDs have photoluminescence quantum yields (PLQY) around 7-39% and exhibit excellent cytocompatibility even at 600 μg mL -1 in NIH/3T3 cells. With such improved properties, Ag 2S-2MPA NIRQDs have a great potential in practical bio-applications. © 2012 The Royal Society of Chemistry.

Tolga Gorgulu A.,Koç University | Cankaya H.,Koç University | Kurt A.,Teknofil Inc. | Speghini A.,University of Verona | And 2 more authors.
Journal of Luminescence | Year: 2012

We have performed detailed experiments to investigate the spectroscopic properties of a new type of tellurite based host doped with thulium: Tm 2O3:(0.70)TeO2(0.15)K2O(0.15)Nb 2O5 having Tm2O3 concentrations of 0.125, 0.25, 0.5, and 1.0 mol%. By performing a JuddOfelt analysis of the absorption bands, we obtained average radiative lifetimes of 2.57±0.20 and 0.35±0.01 ms for the 3H4 and 3F 4 levels, respectively. Furthermore, we also observed that an increase in the Tm2O3 concentration from 0.125 to 1.0 mol% results in a decrease of the measured fluorescence lifetime from 814 to 439 μs and from 258 to 47 μs for the 3H4 and 3F4 levels, respectively, due to efficient non-radiative decay. The highest quantum efficiency of 32% was obtained for the sample doped with 0.125 mol% Tm2O3 for the 3H4 level. Results show that cross relaxation becomes important as the ion concentration is increased, leading to the quenching of the 1460-nm band and enhancement of the 1860-nm emission. The highest emission cross section of 6.85×10-21 cm2 measured for the 1860-nm band reveals the potential of this host for the development of 2-μm lasers in bulk glass as well as fiber media. © 2011 Elsevier B.V. All rights reserved.

Natali Cizmeciyan M.,Koç University | Cankaya H.,Koç University | Kurt A.,Teknofil Inc | Sennaroglu A.,Koç University
Optics InfoBase Conference Papers | Year: 2011

By employing different dispersion compensation schemes, we obtained femtosecond pulses with duration as short as 92 fs and pulse energy as high as 0.45 nJ from a Kerr-lens mode-locked Cr:ZnSe laser operated near 2420 nm. © 2011 Optical Society of America.

Murib M.S.,Hasselt University | Demir A.,Koç University | Demir A.,JDSU | Isci S.,Koç University | And 6 more authors.
European Physical Journal: Special Topics | Year: 2014

Elastic light scattering is performed in the original band of optical fiber communication at 1300 nm for a 500 μm sapphire microsphere placed on a silica optical fiber half coupler. The morphology dependent resonances (MDRs) are observed in the transverse magnetically (TM) polarized and transverse electrically (TE) polarized 0∘ transmission and 90∘ elastic scattering obtained from the sapphire microsphere. The TE and TM MDRs can be detected selectively with the use of a Glan polarizer. The TE and TM polarization selectivity provides the ability to select relative MDR to BG levels. The TM polarization provides higher MDR signal to background ratio (SBR) and is suitable for optical monitoring, biological sensing or any other optoelectronic application that requires a high resolution optical filter. The polar angular mode spacing of 0.36 nm of the resonances correlates well with the optical size of the sapphire microsphere. The autocorrelation of the 90∘ elastic scattering spectra also shows peaks at 0.36 nm. The spectral linewidths of the resonances are on the order of 0.1 nm, which corresponds to quality factors on the order of 104. A sapphire sphere with a radius of 500 μm and relative refractive index of 1.31, resonances will red-shift by 1.01 nm (0.077%). This shift is on the order of 10 linewidths, making sapphire biophotonic sensors an interesting alternative to silica biophotonic sensors. © 2014, EDP Sciences and Springer.

Cankaya H.,Koç University | Natali Cizmeciyan M.,Koç University | Beyatli E.,Koç University | Tolga Gorgulu A.,Koç University | And 2 more authors.
Optics Letters | Year: 2012

We report a narrow-linewidth, tunable, gain-switched Cr:ZnSe laser operating between 2255 and 2455 nm. The spectral width of the laser was reduced from 125 nm to 0.3 nm by using injection seeding. Seeding was achieved with a second tunable CW Cr:ZnSe laser. The output wavelength was varied by tuning the wavelength of the seed laser. The seeded oscillator produced as high as 157 μJ pulses with 598 μJ incident pump pulse energy at a repetition rate of 1 kHz. The slope efficiency was determined to be 26%. © 2012 Optical Society of America.

Yorulmaz I.,Koç University | Beyatli E.,Koç University | Kurt A.,Teknofil Inc. | Sennaroglu A.,Koç University | Demirbas U.,Antalya International University
Optical Materials Express | Year: 2014

We report a low-threshold and efficient Alexandrite laser that is pumped by only one state-of-the-art single-spatial-mode diode. The pump diode provided 170 mW of output power at 635 nm. In continuous wave (cw) laser experiments, we demonstrated lasing thresholds as low as 13 mW, slope efficiencies as high as 36%, output powers up to 48 mW, and a tuning range extending from 736 nm to 823 nm. Laser slope efficiency, laser output power, fluorescence lifetime, and emission intensity were further shown to decrease monotonically with increasing temperature. Pure cw operation could be obtained under most circumstances. However, self- Q-switching (SQS) was also observed in slightly misaligned laser cavities. During SQS, stable pulses with pulsewidths in the 5-15 μs range and pulse repetition rates in the 10-35 kHz range have been obtained. We believe that this compact and efficient Alexandrite laser system may be an attractive source for several applications. © 2014 Optical Society of America.

Bilici T.,Bogazici University | Tabakoglu H.O.,Bogazici University | Topaloglu N.,Bogazici University | Kalaycioglu H.,Koç University | And 3 more authors.
Journal of Biomedical Optics | Year: 2010

Our aim is to explore the welding capabilities of a thulium (Tm:YAP) laser in modulated and continuous-wave (CW) modes of operation. The Tm:YAP laser system developed for this study includes a Tm:YAP laser resonator, diode laser driver, water chiller, modulation controller unit, and acquisition/control software. Full-thickness incisions on Wistar rat skin were welded by the Tm:YAP laser system at 100 mW and 5 s in both modulated and CW modes of operation (34.66 W/cm2). The skin samples were examined during a 21-day healing period by histology and tensile tests. The results were compared with the samples closed by conventional suture technique. For the laser groups, immediate closure at the surface layers of the incisions was observed. Full closures were observed for both modulated and CW modes of operation at day 4. The tensile forces for both modulated and CW modes of operation were found to be significantly higher than the values found by conventional suture technique. The 1980-nm Tm:YAP laser system operating in both modulated and CW modes maximizes the therapeutic effect while minimizing undesired side effects of laser tissue welding. Hence, it is a potentially important alternative tool to the conventional suturing technique. © 2010 society of Photo-Optical Instrumentation Engineers.

BeyatlI E.,Koç University | Naghizadeh S.,Koç University | Kurt A.,Teknofil Inc. | Sennaroglu A.,Koç University
Applied Physics B: Lasers and Optics | Year: 2012

We report a low-threshold continuous-wave Tm:YAG laser that can be excited near 785 nm with low-cost, single-mode AlGaAs laser diodes. Low-threshold operation was achieved using a tightly focused, astigmatically compensated x-cavity containing a 2-mm-thick Tm:YAG crystal with 5 % Tm3+ concentration. Two linearly polarized single-mode diodes operating at 785.8 nm were polarization coupled to end pump the resonator. With a 6 % output coupler, as high as 32 mW of output power could be obtained at 2016 nm with 184 mW of incident pump power. The output could be further tuned in the 1935-2035 nm range. Slope efficiency measurements indicated that cross-relaxation was very effective at this doping level. With a 2 % output coupler, lasing could be obtained with as low as 32.3 mW of pump power. In the limit of vanishing output coupling, the incident threshold pump power could be reduced to as low as 25 mW. To our knowledge, this is among the lowest lasing thresholds reported to date for continuous-wave, room-temperature thulium lasers. © 2012 Springer-Verlag.

Cizmeciyan M.N.,Koç University | Cankaya H.,Koç University | Kurt A.,Teknofil Inc. | Sennaroglu A.,Koç University
Applied Physics B: Lasers and Optics | Year: 2012

We employed various low-cost dispersion compensation methods to generate femtosecond pulses from a Kerr-lens mode-locked (KLM) Cr:ZnSe laser operating near 2400 nm. Prism pairs made of CaF 2 and MgF 2 and slabs of BK7 and YAG were tested. Pulses as short as 92 fs were obtained when a CaF 2 prism pair was used in the resonator with a 1% output coupler. With a 6% output coupler and CaF 2 prism pair, pulse energies as high as 1.8 nJ were obtained. The KLM operating point was further analyzed for different dispersion compensation scenarios by using the soliton area theorem to determine the nonlinear refractive index (n 2) of Cr:ZnSe. Results gave an n 2 value of (1.2 ± 0.2) × 10 -18 m 2/W in agreement with previous reports. © Springer-Verlag 2012.

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