▎ 摘　　要

A tunable, passively Q-switched thulium doped fluoride fibre (TDFF) laser using a reduced-graphene oxide-silver (rGO-Ag) thin film as a saturable absorber (SA) for S band operation is proposed and its efficacy demonstrated. Over a pump power range of 91.4 mW up to 158.6 mW, passively generated Q-switched pulses are observed with repetition rates from 20 to 34.5 kHz and pulse widths from 3.1 to 7.1 mu s. The highest pulse energy observed is 101.2 nJ with a signal to noise ratio of similar to 42 dB. The proposed laser has a tuning range similar to 52 nm from 1458 to 1510 nm with a tunable bandpass filter (TBPF) introduced into the cavity.