Indium Tin Oxide-based Q-switched pulse fiber laser for sensing application

Abstract

We demonstrate a novel method of ring cavity Q-switched pulse erbium-doped fiber laser (EDFL) for liquid ammonia sensors. Q-switched pulse is generated using an indium tin oxide (ITO) deposited onto a side-polished fiber (SPF) as a saturable absorber (SA). The generated Q-switched pulses exhibit a repetition rate from 15.22 kHz to 28.28 kHz when the pump power is tuned from 77.2 mW to 211.60 mW. The shortest pulse width retrieved was 6.42 µs with a pulse energy of 11.23 nJ. A stable Q-switched pulse was obtained from the cavity configuration, with the repetition rate of 28.28 kHz. This pulse was then being used as a reference for the ammonia sensing purposes. When the liquid ammonia was injected into the setup, the wavelength and frequency shifts was observed by increasing the ammonia concentrations. From the results, the sensor can achieve good linear responses. To the best of our knowledge, this is the first report of Q-switched pulse EDFL based on side-polished fiber indium tin oxide (SPF-ITO) as a Q-switcher of the pulsed laser and a sensing transducer at the same time. These results indicates that the proposed SA is suitable for generating ultrashort pulse and optical sensors.