Browsing by Author "Gündoğdu, Sinan"

Now showing items 1-12 of 12

    • Correlation of TEM data with confined phonons to determine strain and size of Ge nanocrystals embedded in SixNy matrix 

      Bahariqushchi, Rahim; Gündoğdu, Sinan; Aydınlı, Atilla (Academic Press, 2017)
      Models that use phonon confinement fail to provide consistent results for nanocrystal sizes in differing dielectric matrices due to varying stress experienced by nanocrystals in different dielectric environments. In cases ...

    • Elimination of catastrophic optical mirror damage in continuous-wave high-power laser diodes using multi-section waveguides 

      Liu, Yuxian; Ebadi, Kaveh; Sünnetçioğlu, Ali Kaan; Gündoğdu, Sinan; Şengül, Serdar; Zhao, Yuliang; Lan, Yu; Zhao, Yongming; Yang, Guowen; Demir, Abdullah (Optica Publishing Group (formerly OSA), 2022-08-29)
      One of the persistent obstacles for high-power laser diodes (LDs) has been the catastrophic optical mirror damage (COMD), which limits the operating power level and lifetime of commercial high-power LDs. The output facet ...

    • Facet cooling in high-power InGaAs/AlGaAs lasers 

      Arslan, Seval; Gündoğdu, Sinan; Demir, Abdullah; Aydınlı, A. (Institute of Electrical and Electronics Engineers Inc., 2019)
      Several factors limit the reliable output power of a semiconductor laser under CW operation, such as carrier leakage, thermal effects, and catastrophic optical mirror damage (COMD). Ever higher operating powers may be ...

    • Facet temperature reduction by separate pumped window in high power laser diodes 

      Arslan, Seval; Gündoğdu, Sinan; Demir, Abdullah; Aydınlı, A. (SPIE, 2018)
      The main optical output power limitation in high power laser diodes is the catastrophic optical mirror damage (COMD) initiated by facet heating due to optical absorption, which limits the reliable power and lifetime of a ...

    • Formation of silicon nanocrystals by laser processing of silicon rich oxides 

      Gündoğdu, Sinan (Bilkent University, 2012)
      Silicon nanocrystals are well known to exhibit strong luminescence in the visible. Extension of this into a nanocrystal network would be beneficial for many applications. In the light of recent advances on exciton-plasmon ...

    • Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers 

      Bahariqushchi, Rahim; Gündoğdu, Sinan; Aydınlı, Atilla (Academic Press, 2017)
      Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating ...

    • Low-loss regrowth-free long wavelength quantum cascade lasers 

      Gündoğdu, Sinan; Demir, Abdullah; Pisheh, Hadi Sedaghat; Aydınlı, Atilla (Institute of Electrical and Electronics Engineers, 2018-12-01)
      Optical power output is the most sought-after quantity in laser engineering. This is also true for quantum cascade lasers operating especially at long wavelengths. Buried heterostructure cascade lasers with epitaxial ...

    • Multi-section waveguide method for facet temperature reduction and improved reliability of high-power laser diodes 

      Ebadi, Kaveh; Liu, Yuxian; Sünnetçioğlu, Ali Kaan; Gündoğdu, Sinan; Şengül, Serdar; Zhao, Yuliang; Lan, Yu; Yang, Guowen; Demir, Abdullah (SPIE, 2022-05-20)
      Catastrophic optical mirror damage (COMD) limits the output power and reliability of lasers diodes (LDs). Laser self heating together with facet absorption of output power cause the facet to reach a critical temperature ...

    • Optical and thermal dynamics of long wave quantum cascade lasers 

      Gündoğdu, Sinan (Bilkent University, 2018-09)
      Quantum Cascade Lasers (QCLs) are coherent light sources that make use of intraband transitions of wavefunction engineered semiconductor quantum wells. They have been designed to emit light in a wide spectral range; from ...

    • Reduced facet temperature in semiconductor lasers using electrically pumped windows 

      Demir, Abdullah; Arslan, Seval; Gündoğdu, Sinan (SPIE, 2019-02)
      The self-heating of semiconductor lasers contributes directly to facet heating and consequently to the critical temperature for catastrophic optical mirror damage (COMD) but the existing facet engineering methods do not ...

    • Thermal characterisation of quantum cascade lasers with Fabry Perot modes 

      Gündoğdu, Sinan; Pisheh, Hadi Sedaghat; Demir, Abdullah; Günoven, M.; Aydınlı, Atilla; Sirtori, C. (SPIE, 2018)
      Quantum cascade lasers are coherent light sources that rely on intrersubband transition in periodic semiconductor quantum well structures. They operate at frequencies from mid-infrared to terahertz. In cases of long ...

    • Time resolved Fabry-Perot measurements of cavity temperature in pulsed QCLs 

      Gündoğdu, Sinan; Pisheh, ‪Hadi Sedaghat; Demir, Abdullah; Günöven, M.; Aydınlı, Atilla; Sirtori, C. (OSA - The Optical Society, 2018)
      Temperature rise during operation is a central concern of semiconductor lasers and especially difficult to measure during a pulsed operation. We present a technique for in situ time-resolved temperature measurement of ...