Title : All-fiber passive Q-switched laser at 1072 nm based on hybrid organic small molecules as a saturable absorber with a high output power
Abstract:
We used a hybrid organic small molecule (HOSM) based Alq3 and NPB as a saturable absorber (SA). The developed SA has a modulation depth of ~ 20% and saturation intensity of 4.8 MW/cm2. At 1072 nm, the SA exhibits absorption of approximately 0.8%. The cavity setup we addressed in this work has a simple configuration, in which we used a 1.40 m of ytterbium-doped fiber as a gain medium. The cavity length was 5 m. The ring cavity was coupled with a 980-nm laser diode through a wavelength-division multiplexer (WDM). A 50:50 optical coupler was used to allow a portion of the output to be extracted for performance monitoring. The remaining output was directed to the SA thin film which was sandwiched between two fiber ferrules. An optical isolator was addressed to eliminate back-reflection. The SA was incorporated into the laser cavity to act as a Q-switcher. The laser produced a pulsing operation with pulse width and repetition rate varied from 12.4 to 2.37 µs and from 32 to 83 kHz, as the input power increased from 76 to 193 mW, respectively. The laser had a high output power of 34 mW with a relatively high signal-to-noise ratio of 57.6 dB. The highest peak power and highest pulse energy generated by the laser were relatively high of 173 mW and 0.4 µJ, respectively. This work shows that the HOSM has a great potential as Q-switcher in pulsed fiber lasers. To the best of the authors' knowledge, this is the first time that HOSM is utilized as a SA device in 1.0 µm region.
