Q-switched and mode-locked fiber laser based on organic metal 8-hydroxyquinoline chelate as saturable absorber at 1.5 µm

Abstract

This paper reports the demonstration of bis(8-hydroxyquinoline) calcium (CaQ2) as a passive saturable absorber (SA) in an erbium-doped fiber laser cavity. The SA has a saturation intensity of 511 MW/cm2 and a modulation depth of 14%. As the SA was incorporated into the cavity, a Q-switching was produced with a repetition rate and pulse duration ranging between 45.5 and 88.2 kHz and 8.76 to 2.9 µs, respectively. Then by increasing the cavity length, a soliton mode-locking operation was developed with a repetition rate and pulse duration of 1.82 MHz and 1.6 ps, respectively. Both lasers had a signal-to-noise ratio (SNR) higher than 63 dB and a central wavelength of 1561 nm. Our results suggest that CaQ2 has the potentials to act as a stable and good-performance SA. We believe that this work is the first to report CaQ2 as a functioning and promising SA.