Dual-wavelength pulse generation in D-shaped fiber Q-switched laser with Ti3Al(C0.5, N0.5)2-PVA saturable absorber

In our investigation, we utilized a Ti 3 Al(C 0.5 , N 0.5 ) 2 -PVA D-shaped fiber as a passive saturable absorber (SA) to establish a stable dual-wavelength pulsed fiber laser induced at 1531 nm and 1558 nm. We fabricate a Ti 3 Al(C 0.5 , N 0.5 ) 2 -PVA exhibiting a 6% modulation depth and a saturation intensity of 0.3 kW/cm 2 . This Ti 3 Al(C 0.5 , N 0.5 ) 2 -PVA D-shaped fiber was integrated into the laser cavity, facilitating Q-switching across a pump power range of 38 mW to 75 mW. Therefore, the repetition rate increased from 35.34 kHz to 51.92 kHz while the pulse width decreased from 6.58 µs to 3.57 µs. The stability of the pulse train was confirmed with a high signal-to-noise ratio (SNR) of 50 dB. The laser attained a maximum output power of 5.7 mW and a pulse energy of 84.75 nJ. These findings establish Ti 3 Al(C 0.5 , N 0.5 ) 2 as a promising Q-switching modulator in the 1.55-µm wavelength range, offering potential applications in compact and efficient pulsed fiber lasers.