Browsing by Author "Thambiratnam, K."

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O-band femtosecond mode-locked laser by using Ni-MOF in praseodymium-doped fluoride fiber
(Elsevier BV * North-Holland, 2024-09-27) Ahmad, H.; Nizamani, B.; Samion, M. Z.; Mutlu, S.; Yilmaz, S. Savaskan; Arsu, N.; Thambiratnam, K.; Ortaç, Bülent
This work reports an ultrafast mode-locked fiber laser at the less investigated region of the O-band using a nickel metal-organic framework (Ni-MOF), which works as a saturable absorber (SA). Ni-MOF was prepared using the high-power laser-induced method. A stable mode-locked laser of 450 fs pulse duration was obtained. The repetition rate and signal-to-noise ratio (SNR) were 0.408 MHz and 52.5 dB, while the lasers operate at a wavelength of 1298.1 nm. At the pump power of 88 mW, the mode-locked laser was characterized to have an average output power of 0.69 mW, corresponding to a pulse energy of 1.69 nJ and a pulse peak power of 3.53 kW. Additionally, harmonic mode-locked laser operation was also achieved above the pump power of 88 mW. With the harmonic mode-locked laser operation, the pulse repetition rate increased to 2.45 MHz when the pump power was 125.7 mW. To the author's knowledge, this is the first report of novel MOF material used as an SA in praseodymium-doped fluoride fiber (PDFF) laser.
Open Access
Zn-MOF as a saturable absorber for thulium/holmium-doped fiber laser
(Institute of Physics Publishing Ltd., 2024-09-19) Ahmad, H.; Chiam, J. W.; Samion, M. Z.; Thambiratnam, K.; Mutlu, S.; Yilmaz, S. S.; Arsu, N.; Ortaç, Bülend
Metal–organic framework (MOF) is a class of material that is highly porous and modular. Due to their unique properties, MOFs have found applications in gas storage, gas separation, sensing, and supercapacitors. [Zn2(H2L)2(1,2-Bis(4-pyridyl)ethene)4]n, zinc (Zn)-based MOF was used in this work to achieve mode-locked operation in a thulium/holmium-doped fiber laser due to its excellent optical absorption at a wavelength of 1925 nm. The saturable absorber (SA) was fabricated by drop-casting a mixture of Zn-MOF and isopropanol on an arc-shaped fiber. The center wavelength of the mode-locked laser is 1906.75 nm, with a maximum average output power of 3.251 mW. The fundamental repetition rate and the pulse width were 12.89 MHz and 1.772 ps. At the same time, the pulse energy and peak power were 252 pJ and 142 W, respectively. To the authors' knowledge, this is the first time an MOF has been used for mode-locked pulse generation in a thulium/holmium-doped all-fiber laser. This work extends the use of MOF material as a saturable absorber for mode-locking applications in near-infrared fiber lasers.