Thulium oxide film as a passive saturable absorber for pulsed fiber laser generation

Abstract

Thulium oxide (Tm2O3) film is demonstrated to work as a passive saturable absorber (SA) for stable pulse generation at 1.55-µm region. The Tm2O3 film was fabricated from a commercially available Tm2O3 embedded into polyvinyl alcohol (PVA) as a film host. The obtained Tm2O3 film has an absorption at 1.55-µm region, which corresponds to energy level diagram of thulium. The Tm2O3 film is switched into the all-fibre ring cavity configuration. Self-started Q-switching operation obtained from 84.13 mW until 159.03 mW pump power. The repetition rate increases from 43.82 kHz and stop at 62.70 kHz, while the pulse duration narrowed from 14.00 µs to 9.50 µs. The stability of the pulse train can be confirmed through signal-to-noise ratio (SNR) of fundamental frequency. The maximum output power and pulse energy is 3.90 mW and 6.22 nJ, respectively. As a result, these findings confirm Tm2O3 can be utilised as a potential passive SA to generate laser pulsing at 1.55-µm region.