Femtosecond mode-locked laser at 1.5 μm region using turmeric-based saturable absorber

We have successful fabricated a turmeric [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6 heptadiene-3,5-dione] thin film with 23% modulation depth using Poly(vinyl alcohol) as a host polymer. The fabricated film was used as saturable absorber (SA) within an erbium doped fiber laser (EDFL) ring cavity, and soliton pulses with a temporal width of 920 fs were readily obtained through the mode-locking process at threshold pump power of 144 mW. The mode-locked laser operated at 1568.4 nm with a 3-dB bandwidth of 3.84 nm. At maximum input LD power of 305 mW, the mode-locked laser has a repetition rate of 3.383 MHz, a pulse width of 920 fs, the average output power of 5.67 mW, a signal-to-noise ratio (SNR) of 77 dB, and pulse energy of 1.67 nJ. To the best of the authors’ knowledge this is the first demonstration using turmeric thin film based SA for ultrafast light generation.