Optical gain in colloidal nanocrystals and solution-processed nanocrystal lasers

My PhD work with Prof. Volkan Demir at Bilkent University has shown that new types of (shape-controlled and composition-tuned) colloidal nanocrystals achieve superior optical gain & lasing properties as compared to conventional colloidal nanocrystals such as quantum dots. We have uncovered that the atomically-flat colloidal nanoplatelets of CdSe and its heterostructure exhibit low threshold optical gain and lasing [1,2,3], long gain lifetimes [2] and exceptionally large modal gain coefficients [1] in these materials. We also proposed and developed all-solution-processed nanocrystal lasers [3, 4]. We found giant two-photon absorption cross-section in nanoplatelets [5] and also achieved exceptionally stable lasing with platelet-in-box approach [7]. We showed tunable gain in the visible range with composition tailoring with gain covering from blue to green and red [2, 6, 8]. In addition, we showed spectral tuning of optical gain with changing biexciton properties in CdSe/CdS nanorod and quantum dot structures [9, 10]. I also developed two-photon and single-photon pumped flexible distributed feedback lasers based on blue-emitting oligofluorenes [11].

Selected Publications:

[1] B. Guzelturk, M. Pelton, M. Olutas, H. V. Demir, "Giant Modal Gain Coefficients in II-VI Nanoplatelets," Nano Lett. 19, 277-282 (2019). Link

[2] B. Guzelturk, Y. Kelestemur, M. Olutas, Q. Li, T. Lian, H. V. Demir, "High-Efficiency Optical Gain in Type-II Semiconductor Nanocrystals of Alloyed Colloidal Quantum Wells," J. Phys. Chem. Lett. 8, 5317 (2017). Link

[3] B. Guzelturk, Y. Kelestemur, M. Olutas, S. Delikanli, H. V. Demir, “Amplified Spontaneous Emission and Lasing in Colloidal Nanoplatelets,” ACS Nano 8, 6599 (2014). Link

[4] B. Guzelturk, Y. Kelestemur, K. Gungor, A. Yeltik, M. Z. Akgul, W. Yue, R. Chen, H. D. Sun, C. Dang, H. V. Demir, “Stable and Low Threshold Optical Gain in CdSe/CdS Quantum Dots: All-Colloidal Frequency Up-Converted Laser" Adv. Mater. 27, 2741 (2015). Selected as Inside Front Cover. Link

[5] M. Olutas*, B. Guzelturk*, Y. Kelestemur, A. Yeltik, S. Delikanli, H. V. Demir, “Lateral Size-Dependent Spontaneous and Stimulated Emission Properties in Colloidal CdSe Nanoplatelets” ACS Nano 9, 5041 (2015). * Equal contribution. Link

[6] Y. Kelestemur, B. Guzelturk, O. Erdem, M. Olutas, T. Erdem, C. F. Usanmaz, K. Gungor, H. V. Demir, “CdSe/CdSe(1–x)Te(x) Core/Crown Heteronanoplatelets: Tuning the Excitonic Properties without Changing the Thickness” J. Phys. Chem. C 121, 4650 (2017). Link

[7] Y. Kelestemur, B. Guzelturk, O. Erdem, M. Olutas, K. Gungor, H. V. Demir, “Platelet-in-Box Colloidal Quantum Wells: CdSe/CdS@CdS Core/Crown@Shell Heteronanoplatelets” Adv. Funct. Mater. 26, 2891 (2016). Link

[8] B. Guzelturk, Y. Kelestemur, M. Z. Akgul, V. K. Sharma, H. V. Demir, “Ultralow Threshold One-Photon and Two-Photon Pumped Optical Gain Media of Blue- Emitting Colloidal Quantum Dot Films,” J. Phys. Chem. Lett. 5, 2214 (2014). Link

[9] Y. Kelestemur, A. F. Cihan, B. Guzelturk, H. V. Demir, “Type-Tunable Amplified Spontaneous Emission from Core-Seeded CdSe/CdS Nanorods Controlled by Exciton-Exciton Interaction” Nanoscale 6, 8509 (2014). Link

[10] A. F. Cihan, Y. Kelestemur, B. Guzelturk, O. Yerli, U. Kurum, H. G. Yaglioglu, A. Elmali, and H. V. Demir, “Attractive versus Repulsive Excitonic Interactions of Colloidal Quantum Dots Control Blue-to Red-Shifting (and Non-shifting) Amplified Spontaneous Emission,” J. Phys. Chem. Lett. 4, 4146 (2013). Link

[11] B. Guzelturk, A. L. Kanibolotsky, C. Orofino-Pena, N. Laurand, M. D. Dawson, P. J. Skabara, H. V. Demir, “Ultralow-Threshold Up-Converted Lasing in Oligofluorenes with Tailored Strong Nonlinear Absorption,” J. Mater. Chem. C 3, 12018 (2015). Selected as Front Cover. Link