Research Project: Özgün Optik Pompolama Yöntemleri ile Geliştirilmiş 2M Civarında Çalışan Sürekli Dalga ve Darbeli Tulyum Katıhal Lazerleri
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Contributors
Funders
ID
TB.00197
Authors
Sennaroğlu, Alphan
Faculty Member
Publications
Low-threshold diode-pumped 2.3-mu m Tm3+:YLF lasers
(IEEE-Inst Electrical Electronics Engineers Inc, 2018) Sennaroğlu, Alphan; Yorulmaz, İsmail; Department of Physics; Graduate School of Sciences and Engineering; KUYTAM (Koç University Surface Science and Technology Center); Laser Research Laboratory; Yes; College of Sciences; Research Center; Laboratory
We demonstrate low-threshold diode-pumped operation of a continuous-wave Tm3+:YLF laser near 2.3 mu m and provide a detailed experimental investigation of its lasing characteristics. A narrow-line, tunable Ti3+:sapphire laser was first used to measure the excitation spectrum and investigate the absorption saturation behavior of the 1.5 at.% Tm3+:YLF gain medium. A single-mode, 120-mW laser diode operating at 792 nm was then used as a pump source to demonstrate low-threshold lasing at 2.3 mu m. With a 1% output coupler, diode-pumped operation could be obtained with as low as 25 mW of incident threshold pump power. With 119 mW of pump power, as high as 10.5 mW of out-put power could be obtained at 2305 nm with a slope efficiency of 11.4%. By using a second, 250-mW laser diode, a resonator with variable output coupling was constructed to measure the threshold pump power and power slope efficiency as a function of output coupling. The minimum threshold pump power at output coupling levels approaching 0% was measured to be 4 mW. Results further showed that the slope efficiency decreased with increasing output coupling beyond 0.7%. The stimulated emission cross section at 2305 nm was further determined to be 0.68 x 10(-20) cm(2) from lasing threshold data.
Graphene mode-locked Cr:LiSAF laser at 850 nm
(Optica Publishing Group, 2015) Canbaz, Ferda; Sennaroğlu, Alphan; Kakenov, Nurbek; Kocabaş, Coşkun; Demirbaş, Ümit; Department of Physics; Laser Research Laboratory; Yes; College of Sciences; Laboratory
We report, for the first time to our knowledge, a mode-locked femtosecond Cr:LiSAF laser initiated with a high-quality monolayer graphene saturable absorber (GSA), synthesized by chemical-vapor deposition. The tight-focusing resonator architecture made it possible to operate the Cr:LiSAF laser with only two 135 mW, 660 nm low-cost single-mode diode lasers. At a pump power of 270 mW, the laser produced nearly transform-limited 68 fs pulses with an average power of 11.5 mW at 850 nm. The repetition rate was around 132 MHz, corresponding to a pulse energy and peak power of 86 pJ and 1.26 kW, respectively. Once mode locking was initiated with the GSA, stable, uninterrupted femtosecond pulse generation could be sustained for hours. The saturation fluence and the modulation depth of the GSA were further determined to be 28 mu J/cm(2) and 0.62%, respectively. (C) 2015 Optical Society of America
2.3-μm Tm3+: YLF laser passively Q-switched with a Cr2+: ZnSe saturable absorber
(OSA - The Optical Society, 2017) Canbaz, Ferda; Sennaroğlu, Alphan; Yorulmaz, İsmail; N/A; Department of Physics; KUYTAM (Koç University Surface Science and Technology Center); Laser Research Laboratory; Yes; College of Sciences; Research Center; Laboratory
We report, what is to our knowledge, the first passively Q-switched operation of a 2.3-mu m Tm3+ : YLF laser by using a Cr2+ : ZnSe saturable absorber. In the experiments, a tunable Ti3+ : sapphire laser was used to end pump the Tm3+ : YLF gain medium inside an x cavity. A Cr2+ : ZnSe saturable absorber was also included in the cavity to initiate passive Q switching. At all pump power levels above lasing threshold, passively Q-switched operation of the Tm3+ : YLF laser could be obtained at 2309 nm with pulse durations and repetition frequencies in the ranges of 1.21.4 mu s and 0.3-2.1 kHz, respectively. Analysis of power dependent repetition rate data further gave an estimated value of 3.1% for the round-trip saturable loss of the Cr2+ : ZnSe saturable absorber.
Kerr-lens mode-locked 2.3-mu m tm3+:YLF laser as a source of femtosecond pulses in the mid-infrared
(OSA - The Optical Society, 2017) Canbaz, Ferda; Sennaroğlu, Alphan; Yorulmaz, İsmail; Department of Physics; KUYTAM (Koç University Surface Science and Technology Center); Laser Research Laboratory; Yes; College of Sciences; Research Center; Laboratory
We report what is to our knowledge a new source of femto-second pulses in the mid-infrared, based on a Kerr-lens mode-locked (KLM) Tm3+ : YLF laser at 2303 nm. An un-doped ZnSe substrate was included in the resonator to provide enhanced nonlinear phase modulation during KLM operation. The Tm3+ : YLF laser was end-pumped with a continuous-wave Ti3+ : sapphire laser at 780 nm. With 880 mW of pump power, we generated 514-fs pulses at a pulse repetition rate of 41.5 MHz with an average power of 14.4 mW. The spectral width (full width at half-maximum) was measured as 15.4 nm, giving a time-bandwidth product of 0.44. We foresee that the wide availability of this gain medium, as well as the straightforward pumping scheme near 800 nm, will make 2.3-mu m, mode-locked Tm3+ : YLF lasers versatile sources of ultrashort pulses in the mid-infrared. (C) 2017 Optical Society of America
Dual-wavelength temporal dynamics of a gain-switched 2-mu m Tm3+:Lu2O3 ceramic laser
(IEEE-Inst Electrical Electronics Engineers Inc, 2018) Canbaz, Ferda; Sennaroğlu, Alphan; Baylam, Işınsu; Department of Physics; Graduate School of Sciences and Engineering; Laser Research Laboratory; Yes; College of Sciences; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Laboratory
We provide a detailed experimental investigation of the energy efficiency and rich temporal dynamics of a gain-switched 2-mu m Tm3+:Lu2O3 ceramic laser pumped near 800 nm. A tunable Ti3+:sapphire laser was used to determine the full excitation spectrum and the optimum pumping bands for the 1.5% Tm3+:Lu2O3 ceramic gain medium. These bands were centered at 774, 796, and 811 nm. The highest output pulse energy was obtained when the pump wavelength was set to 796 nm. In the experiments, a free-running x-cavity was used to investigate the energy efficiency of the Tm3+:Lu2O3 ceramic laser. Extracavity grating-dispersed output and prism-tuned resonator were used to further assess the role of cross-relaxation for the 1.5% Tm3+:Lu2O3 ceramic. Finally, we demonstrate that as the pump energy was increased, a transition occurred from-single-wavelength output (2068 nm) to dual-wavelength multipulse output (2068 and 1968 nm). We performed systematic temporal and spectral characterization measurements by using the free-running resonator, extracavity-grating-dispersed laser output, and prism-tuned resonator to investigate how the laser pulses at 1968 and 2068 nm evolved in time. A plane-wave rate equation model was further used to investigate the temporal dynamics of the Tm3+:Lu2O3 ceramic laser and provided predictions in qualitative agreement with experimental data.
