Fe3O4 nanoparticle-enabled Q-switched pulse generation in fiber laser

Bulk α-alumina embedded tapered fiber as Q-switcher in an erbium-doped fiber laser

“…As clearly depicted in figure 8(a), both Sb-SAs operated in slightly larger pump power ranges as compared to this work, which lie within 81.00-445.00 mW [15] and 41.00-345.00 mW [14]. Meanwhile, the other SAs experienced either high threshold condition [9,10,16,17] or SA oversaturation [9,[11][12][13] which resulted in the disappearance of Q-switched pulses. Besides that, adjustable Q-switched outputs could be realized by heating a section of a polarization-maintaining fiber in a Sagnac loop mirror [9] and varying the back-circulating powers of the optical couplers [12].…”

“…The repetition rate was tunable from 19.17 kHz to 43.24 kHz with minimum pulse width of 7 μs. Up to 150.32 nJ pulse energy was achieved at a pump power of 308.6 mW, which shows a significant improvement in comparison to previous works on Al 2 O 3 -SA [9][10][11] and newly emerged material-based SAs, such as molybdenum aluminum boride (MoAlB) [12], black phosphorus (BP) [13], antimonene (Sb) [14,15], aluminum (Al) [16], and iron oxide (Fe 3 O 4 ) [17]. The experimental findings indicate that α-Al 2 O 3 -SA exhibited excellent nonlinear absorption properties, which further promotes the exploration of metal oxide-based photonic devices in the near future.…”

“…Thus, the extended propagation distance in lateral interaction scheme of tapered fiber pushes the damage threshold of SA device to be higher than fiber ferrule-based structures. For instance, Ban and co-workers [17] fabricated TF-based SA with black Fe 3 O 4 onto 20.4 μm waist diameter. However, numerical simulations by Zhang et al [22] emphasized the difficulty of total internal reflection to occur when the material was deposited directly onto taper waist.…”

“…Conversely, a higher percentage of signals needs to be tapped out for higher energy outputs [12]. However, in other cases, the large power extraction caused the threshold condition to realize Q-switched pulse to be significantly increased [17]. In spite of low saturation intensity of the Al-SA and 90% back-coupling of light into the amplifying section of the laser cavity, a large pump power was acquired to compensate the large insertion loss of the SA (10 dB) [16].…”

Dual-Wavelength Passively Q-Switched Erbium-Doped Fiber Laser Incorporating Calcium Carbonate Nanoparticles as Saturable Absorber

“…In the cavity of a fber laser, the SA or "Q-switcher" exhibits varied optical absorption when pulses of diferent intensities propagate through it. Tis can be attributed to the saturable absorption characteristics of SA materials [13]. Various types of functional materials are used to create passively Q-switched pulses.…”