Development of CW and Pulsed Thulium Ytterbium Co-doped Fiber Lasers Using Nano-engineered Yttria-alimina-silica Based Gain Medium in Conjunction with Cladding Pumping Technique

What is it about?

We develop new nano-engineering octagonal shape double-clad Thulium-Ytterbium co-doped fiber (TYDF) to provide an efficient lasing at 1950 nm region based on energy transfer from Ytterbium to Thulium ions. With a linear configuration, the TYDF laser (TYDFL) operates at center wavelength of 1936.4 nm, 1958.6 nm and 1967.5 nm at gain medium lengths of 5 m, 10 m and 15 m, respectively. The proposed laser produces the highest efficiency of 9.9 % at 10 m long TYDF and the lowest threshold pump power of 400 mW at a longer TYDF length of 15 m. The Q-switched laser operates at 1960 nm region is achieved by exploiting a multi-walled carbon nanotubes (MWCNTs) polymer composite film based saturable absorber (SA). The proposed TYDFL generates a stable pulse train with repetition rates and pulse widths ranging from 18.9 kHz to 35.1 kHz and 7.94 to 1.52 μs, respectively by varying the multimode 980 nm pump power from 440 mW to 528 mW. The maximum pulse energy of 11.2 nJ is obtained at the pump power of 512 mW. A higher performance Q switching is expected to be achieved with the optimization of the SA and laser cavity. A mode-locked TYDFL is also demonstrated using a commercial graphene oxide (GO) paper as SA to operate at 1942.0 nm at a threshold multimode pump power as low as 1.8 W. The mode-locked TYDFL has a repetition rate of 22.32 MHz and calculated pulse-width of 1.1 ns.

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Why is it important?

Using Nano-Engineered Yttria-Alumina-Silica based Gain Medium in Conjunction with Cladding Pumping.

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