Gold Nanorods as Single and Combined Saturable Absorbers for a High-Energy <named-content content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="TeX">$Q$</tex-math></inline-formula></named-content>-Switched Nd:YAG Solid-State Laser

Abstract

Gold nanorods (GNRs) with surface plasmon resonance peak at 1063.8 nm were fabricated and experimentally exploited as the single and combined saturable absorber (SA) in a Q-switched Nd:YAG laser for the first time. In the situation using GNRs as a single SA, the maximum pulse energy of 19 J was achieved at a pulse repetition rate of 20 kHz. However, due to the small effective modulation depth of the GNRs, microsecond pulses were generated in such a GNRs-based passively Q-switched laser. A novel configuration using GNRs as a combined SA in an acoustooptic Q-switched Nd: YAG laser was proposed. The small nonlinear loss modulation induced by the GNRs played a distinctive role in flexibly manipulating the nanosecond pulse waveforms. Our study demonstrated the feasibility of generating high-energy pulses by singly using GNRs-based SA in all solid-state lasers. Meanwhile, a new application mode incorporating GNRs as a combined SA was studied, providing an alternative method to take advantage of the nanomaterial-based SA with a relatively small modulation depth.

Passively Q-switched Tm-doped fiber laser based on concave gold bipyramids assembled quasi-2D saturable absorber

“…In recent years, developing novel saturable absorbers (SAs) for passively Q-switching and mode-locking techniques is an important method of generating pulses [1][2][3]. Nanomaterials, like carbon nanotubes [4,5], graphene [6,7], topological insulators [8], transition metal dichalcogenides [2,9], noble metal nanoparticles [10,11], and black phosphorus [12], have been extensively investigated and applied to be SAs to obtain pulsed operation.…”

Gold nano-triangles as saturable absorbers for a dual-wavelength passively Q-switched Nd:GYSGG laser

“…The shortest pulse width was 374 ns at a pulse repetition frequency of 250 kHz. The 374 ns pulse width is much shorter compared to previous work (3.6 µs) which was obtained in a diode-side pumped passively Q-switched Nd:YAG laser with gold-nanorods as single SAs [12].…”

“…Once the pump power is increased, the pulse trains become unstable with amplitude jitters which are common in passively Q-switched lasers [10,13,14]. The reason for the unstable pulse trains could be the oversaturation of the SA at high-incident intensity [12]. When we inserted a glass substrate without GNTs in the laser cavity, Q-switched pulses were not observed at laser operation.…”

“…The pulse width seems a little long. The reason could be that the pump power is low, and the modulation of the SA is not high enough [10][11][12]. The temporal pulse shape of the shortest 374 ns width at the pump power of 8.5 W is shown in figure 7.…”

Silica-coated gold nanorods as saturable absorber for bound-state pulse generation in a fiber laser with near-zero dispersion

“…Their unique properties have caused much enthusiasm in the field of laser technology. So far, GNRs have been viewed as a promising SA for the generation of ultra-short pulses in fiber lasers, ranging from 1.0 µm to 2.0 µm [38][39][40][41][42][43][44]. However, the low optical damage threshold of GNRs makes them unfavorable for improving the performance of the laser, which must operate at high optical power.…”