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İstanbul, Turkey

Bilici T.,Bogazici University | Tabakoglu O.,Bogazici University | Kalaycioglu H.,Bilkent University | Kurt A.,Teknofil Inc | 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.,Koc University | Cizmeciyan M.N.,Koc 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.

Yorulmaz I.,Koc University | Beyatli E.,Koc University | Kurt A.,Teknofil Inc | Sennaroglu A.,Koc 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.

Cankaya H.,Koc University | Natali Cizmeciyan M.,Koc University | Beyatli E.,Koc University | Tolga Gorgulu A.,Koc 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.

Chaudhry M.R.,Koc University | Rashid Z.,Koc University | Uysalli Y.,Middle East Technical University | Kurt A.,Teknofil Inc | And 2 more authors.
Progress in Electromagnetics Research Symposium | Year: 2015

Electromagnetic numerical studies of silicon and diamond microdisks coupled with silicon and diamond slab waveguides are performed in the CO2 laser emission region in the mid-infrared. Microdisk is the 2D analog of the microsphere and the slab waveguide is the 2D analog of the rectangular optical waveguide. The evanescent coupling between the waveguide and the microdisk results in efficient pumping of the whispering gallery modes of the microdisk. On-resonant and off-resonant studies are performed by tuning the laser wavelength to the microdisk whispering gallery modes.

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