Q-switched and mode-locked laser based on aluminium zinc oxide deposited onto D-shape fiber as a saturable absorber
Bilal Nizamani, Muhammad Imran Mustafa Abdul Khudus, Sameer Salam, Mustafa Mohammed Najm, A.A.A. Jafry, Effariza Hanafi, M. Yasin, Sulaiman Wadi Harun
Abstract
In contrast to the direct insertion of a saturable absorber (SA) to fiber laser cavity, the D-shape fiber coated with a SA material introduces more optical non-linearity and SA damage threshold is increased due to the evanescent field light-matter interaction. In this work, a D-shape fiber coated with aluminium-doped zinc oxide is used as a saturable absorber (SA). A Q-switched operation was obtained at 1559.6 nm. The pulsing was initiated at a low pump power of 25 mW and up to 198 mW, in which the pulses shortened from 6.67 µs to 2 µs and the repetition rate increased from 23.26 kHz to 83.9 kHz. The same technique was used to produce a nanosecond pulse mode-locked operation at 1564.8 nm, with pulse width and a repetition rate of 470 ns and 0.97 MHz, respectively. The laser produced a very stable Q-switching and mode-locking operations with a high signal to noise ratio of ~65 dB.