Q-switched pulse operation in erbium-doped fiber laser subject to zirconia (ZrO2) nanoparticles-based saturable absorber.

In this paper, the zirconia (ZrO2) nanoparticles-based saturable-absorber (SA) have been incorporated in an erbium-doped fiber laser (EDFL) cavity for achieving a Q-switched pulse operation. The implementation of the zirconia nanoparticles-based powder on the fiber facet was accomplished using the index-matching gel's adhesion effect. The incorporation of SA in the laser cavity yielded a stable and self-starting Q-switched operation under 19.36 mW pump power that corresponded to the emission wavelength of 1557.29 nm. Additionally, it was observed that the EDFL's emission wavelength tuned from 1557.29 nm to 1562.3 nm , and the repetition rates and pulse width ranged from 61.2 to 130 kHz and 7.9 to 3.6 µs, respectively, as the pump power was increased from 19.36 to 380.16 mW. Measured experimental results reveal that at a maximum pump power of 380.16 mW, the maximum average output power, peak power, and pulse energy were noticed to be 1.17 mW, 2.5 mW, and 9 nJ, respectively. A 52 dB suppression in side bands was found at a pump power of 380.16 mW. Moreover, the stability and threshold tolerance of the EDFL has also been discussed in detail. These findings suggest that nanoparticle-based saturable absorbers have potential applications in a pulsed source, making it easier to implement in fiber cavity-based systems.

Passively Q-Switched Er-Doped Fiber Laser Based on Bentonite Clay (Al2H2O6Si) Saturable Absorber.

This paper presents the investigations toward the direct use of bentonite clay (Al2H2O6Si) nanoparticles to act like a saturable absorber (SA) for the Q-switched pulse operation of an erbium-doped fiber laser (EDFL). The measured results reveal that with the incorporation of bentonite clay nanopowder as a SA, an EDFL is realized with a Q-switching mechanism starting at a pump power of 30.8 mW, and a Q-switched emission wavelength was noticed at 1562.94 nm at 142 mW pump power. With an increased pump from 30.8 mW to 278.96 mW, the temporal pulse parameters including minimum pulse duration and maximum pulse repetition rates were reported as 2.6 µs and 103.6 kHz, respectively. The highest peak power, signal-to-noise ratio, output power and pulse energy were noticed to be 16.56 mW, 51 dB, 4.6 mW, and 47 nJ, respectively, at a highest pump power of 278.96 mW. This study highlights the significance of bentonite clay (Al2H2O6Si) nanoparticles as a potential candidate for a saturable absorber for achieving nonlinear photonics applications.

Ameliorating the stability of erbium-doped fiber laser using saturable absorber fabricated by the pulsed laser deposition technique.

In this paper, we present the performance and stability of an erbium-doped fiber laser (EDFL) based on ZnO saturable-absorber (SA) prepared using two schemes: solution method (SM) and pulsed laser deposition technique (PLDT). It was observed that EDFL with ZnO-SA prepared using SM emits at 1561.25 nm under a pump power of 230 mW. As the pump power is increased from 22.2 mW to 75.3 mW, the pulse duration decreases from 24.91 to 10.69 µs, and the pulse repetition rates increase from 11.59 to 40.91 kHz. Besides at pump power of 75.3 mW, the peak power, pulse energy, and average output power are measured as 0.327 mW, 2.86 nJ, and 0.18 mW, respectively. However, when PLDT-based SA was incorporated into the ring cavity, the emission wavelength is noticed at 1568.21 nm at a pump power of 230 mW. With the increase in pump power from 22.2 mW to 418 mW, the pulse repetition rates increase from 10.79 to 79.37 kHz and the pulse width decreases from 23.58 to 5.6 µs. Furthermore, the peak power, pulse energy, and average output power are observed to be 10.9 mW, 74 nJ, and 5.35 mW, respectively. The stability of EDFL based on SAs prepared using SM and PLDT has also been investigated. To the best of the author's knowledge, it is the first comparison of performance and long-term stability of EDFL based on two experimental techniques SM and PLDT-based SAs. These findings suggest that PLDT-based SAs provides optimum stability over a long period and enhanced the performance of fiber lasers compared to the SAs prepared using the conventional SM technique. This study paves the way for the development of ultra-stable SAs for their potential applications in pulsed laser sources and photonic devices.

Measurements of experimental transition probabilities of 3p54p → 3p54s arrays in neutral argon.

We have determined the absolute transition probabilities of 27 emission lines of neutral argon originating from the 3p54p→3p54s transition array in the wavelength region from 650 to 1100 nm using an argon-filled hollow cathode discharge lamp. The absolute transition probabilities have been deduced using the lifetimes of the upper levels and the measured branching fractions. Atomic oscillator strengths and relative line strengths for all the transitions have been computed using calculated transition probabilities. The experimentally determined transition probabilities are found to be in good agreement with that calculated in the intermediate coupling (IC) scheme. The comparison of experimentally determined transition probabilities with reported theoretical transition probabilities confirms that the IC scheme for the lower as well as for the upper levels seems to be a useful scheme for the level designation for the 3p54p to 3p54s configuration-based levels in argon. Furthermore, the measured relative line strengths are used to validate the J-file sum rule for the 3p54p→3p54s transition array of argon. The reported transition probabilities, oscillator strengths, and relative line strengths are compared with the published data, showing good agreement.