We report a 1064 nm Nd:YAG solid-state laser Q-switched by the dynamic thermal lens effect. The feasibility of using the thermal lens effect to realize Q-switch was proved based on the theoretical ...analysis of the dynamic thermal lens effect and the simulation of the Q-switched rate equation. Further, a thermal lens Q-switched experimental device with an 808 nm pumped Nd:YAG laser was constructed. The output laser beams with a repetition rate of 100 Hz, pulse width of 15.02 ns, single pulse energy of 11.9 mJ, and working wavelength of 1064 nm were realized by thermal lens Q-switch under the pump power of 412 W and pump pulse width of 80μs. The beam quality factors of the output pulse in x and y directions were 2.63 and 2.94, respectively. The results demonstrate that using a thermal lens Q-switch can generate laser beams with high energy and short pulse widths.
•A method of using a thermal lens to realize Q-switch in a solid laser is proposed, and its feasibility is demonstrated.•The Q-switched Nd:YAG laser utilizing a dielectric thermal lens was first developed experimentally.•The output pulse laser has high power, narrow pulse width and high beam quality.
Using an acousto-optic modulator of zero-order transmission as the Q-switch, single-frequency laser pulses were obtained in a ring cavity fiber laser with the seed injection technique. The ...acousto-optic modulator avoided the frequency-shift resulting from the RF driver signal in the first-order transmission. As the seed laser, a distributed-feedback fiber laser based on the π phase-shift fiber Bragg grating was directly inserted into the ring cavity. It decreased the cavity loss and improved the injection efficiency, compared with the common injection by an optical fiber coupler. With the seed laser power over 150 μW, the single-frequency laser pulses with the wavelength of 1550.12 nm were achieved and verified by a scanning Fabry–Perot interferometer. Under the pump power of 450 mW, the pulse duration ranged from 90 ns to 350 ns with the repetition frequency from 10 kHz to 50 kHz. The measured linewidth demonstrated that the pulse laser was almost transform limited: 1.9 MHz for a train of pulses of 50 kHz repetition frequency, 350 ns pulse duration and 36.2 mW maximum average power.
•An AOM with zero-order transmission is used as the Q-switch.•Seed laser is directly insert into the fiber ring cavity.•A transform-limited pulse laser is obtained with its linewidth of 1.9 MHz and duration of 350 ns
A passive Q-switcher based on graphene nanoplatelets (GnP) doped with polyvinyl alcohol (PVA) is proposed for pulse laser generation at 2.0 µm region. An optimized solution casting approach is ...adopted in the customized preparation of a 12.04 wt.% weight ratio of GnP to PVA. The fabricated saturable absorber (SA) is characterized using field emission scanning electron microscope (FESEM), which confirmed the embedment of GnP in PVA composite. A 5 m long thulium doped fiber (TDF) is used as a gain medium in the laser cavity measurement. Our characterization demonstrates dual-wavelength Q-switched pulse generation at 1904.0 nm and 1904.9 nm for input power ranging from 644 mW to 698 mW, respectively. The repetition rate is tunable from 69 kHz to 98 kHz with the shortest pulse width of 1.4 µs. The calculated output peak power, pulse energy and signal-to-noise ratio are recorded at 143 mW, 0.21 µJ and 35 dB, respectively. Notably, the present work is the first-ever work of a Q-switcher based on GnP doped with PVA host at 2.0 µm region.
A 25-year-old aesthetician was operating Q-switch pulse (SPECTRA) cosmetic laser machine of 1,064 nm wavelength, for the purpose of skin bleaching. The probe suddenly slipped over the plastic sheet ...that had been placed to avoid COVID-19 exposure after which she complained of sudden loss of vision. She was diagnosed as having vitreous hemorrhage in her right eye and was treated conservatively for one month. She then complained of central scotoma and was diagnosed to have developed a full-thickness macular hole, for which she was advised vitrectomy surgery. The purpose of this case report is to emphasize the importance of taking precautions during the COVID-19 era and while doing that making sure how to handle the machines so as not to inflict any accidental injury to the operating physician. Macular Holes following skin bleaching with Nd:YAG laser occurring in operating aesthetician is rare as compared to that occurring in the patients.
Antimonene, as a novel two-dimensional material, has received extensive attention in recent years. It has similar properties to most semiconductor materials and has many other materials unmatched ...characteristics. Herein, we prepare antimonene nanosheets by the liquid-phase exfoliation method, and fabricate antimonene-based saturable absorbers (SA) according to their saturable absorption characteristics and successfully apply them in fiber lasers to achieve stable passively Q-switched output with a center wavelength of 1558 nm. The saturation intensity of antimonene-based SA is 1.52 MW/cm2, and the modulation depth is 11.63% in our experiment. The pulse duration is varied from 5.10 μs to 1.42 μs, and the repetition frequency is changed from 25.6 kHz to 124.1 kHz, with the pump power from 81 mW to 445 mW in the passively Q-switched operation. The experimental results fully reveal the huge potential and nonlinear optical properties of antimonene used in pulsed fiber lasers and expand the scope of new optical applications.
•Successfully employed Sb-SA in erbium-doped fiber lasers based on its saturated absorption characteristics.•The Q-switched pulse with a center wavelength of 1558 nm and pulse duration of 1.42 μs was realized.•The Q-switched output pulse has long-term stability without obvious spectral changes and intensity fluctuations.
In this work, Molybdenum Titanium Aluminum Carbide (Mo2Ti2AlC2) was examined to function as a reliable saturable absorber (SA) for stable pulse generation in the 1563 nm wavelength. To create the ...Mo2Ti2AlC2-PVA film, Mo2Ti2AlC2 powder with > 200 nm particle size was dispersed into polyvinyl alcohol (PVA) and dried to form a film. The Mo2Ti2AlC2-PVA film had a linear absorption coefficient of about 1.5 dB at the Q-switched working wavelength. The Mo2Ti2AlC2-PVA film was sandwiched between fiber ferules and analyzed in the Erbium-Doped Fiber (EDF) ring cavity design. Self-started Q-switching was realized with pump power ranging from 20 mW to 55 mW. The pulse width shrunk from 21.7 µs to 8.9 µs while the repetition rate increased from 20.45 kHz to 40.40 kHz. The fundamental frequency had a signal-to-noise ratio (SNR) of 61 dB, implying good stability of the pulsed laser. The highest output power and pulse energies are 1.1 mW and 27.2 nJ, respectively. These results demonstrate that Mo2Ti2AlC2 can be a good alternative passive SA to produce laser pulsing in the 1.55-micron wavelength.
•Design and fabrication of a compact unstable positive branch multi-pass telescopic amplifier.•Assembly and operation of a homemade Q-Switched Nd:YAG oscillator coupled with multi-pass telescopic ...amplifier.•Output beam diagnosis.•Beam tuning study by investigating beam divergence control with mirror pair-separation in multi-pass telescopic amplifier.
Here, an unstable positive branch multi-pass telescopic amplifier has been designed and fabricated. At first, a stable Q-switched Nd: YAG oscillator has been implemented operating in near fundamental mode. A well-designed pair of mirrors is elaborated for the multi-pass telescopic amplifier to extract the maximum energy from the gain medium within a compact volume. This configuration exhibits a small angular beam divergence (typically 0.06 mrad). Furthermore, the tuning of beam diameter at far field is investigated in terms of mirrors separation. Hence, it is feasible to tune the beam diameter during remote sensing not only to reduce the divergence but also to focus the beam at the target under certain conditions. The experimental arrangement gives out a near field donut-shaped profile with 1 J pulse energy, 10 ns, 1 Hz at 1064 nm. Systematic measurements are carried out to obtain the small-signal gain and saturation properties in terms of various pump energies and the correlation of those parameters are elucidated with the beam profile in near field configuration. The output beam profile is empirically recorded at different distances as far as 50 m to verify the theoretical model given by the physical optical propagation algorithm of the Zemax software. The latter simulates the laser beam intensity distribution in the far field. The measurements taken by the beam profiler are in good agreement with those given by Zemax simulation.
New promising optical glasses containing cobalt ions in tetrahedral coordination have been synthesized, their mechanical and optical properties, as well as their characteristic temperatures, have ...been studied. High-quality glasses of the composition (70-x)ZnO–10SiO2-(20 + x)B2O3 (x = 0; 5; 10 wt%) doped with 0.1, 0.3, and 0.6 wt% CoO have been synthesized for the first time. The selected glass compositions were close to the eutectic one in the ZnO–SiO–B2O3 system. This made it possible to reduce the glass synthesis temperature from the 1350–1500 °C, described in the literature for similar zinc borosilicate glasses, to the 1170 °C. The presence of tetrahedral cobalt ions (CoO4) was identified by the absorption bands at 17000 cm−1 (4A2(4F) → 4T1(4P)) and at 6954 cm−1 (4A2(4F) → 4T1(4F)). Then the intense absorption bands in the visible region have been attributed to the 4A2(4F) → 2A1(2G), 4A2(4F) → 4T1(4P), 4A2(4F) → 2T2(2G), 4A2(4F) → 2T1(2G) and 4A2(4F) → 2E(2G) transitions. The most intense absorption band of octahedral cobalt ions (CoO6) corresponds to the 4T1(F) → 4T1(P) transition and is located in the region of 18000–20000 cm−1. According to analysis of Co2+ absorption spectra, the tetrahedral Co2+ ions concentration increased with increasing the CoO concentration in glasses. To study the nature of the bond between cobalt ion and ligands, the values of the splitting force of the ligand field (10Dq) and Racah parameter B were determined.
•Low melting ZnO–SiO2–B2O3 Co-doped (0.1–0.6 wt% CoO) glasses were synthesized.•Synthesized glasses contain tetrahedral CoO4 groups in their structure.•For Co2+ the ligand field splitting force and Racah parameter B were determined.
We report on the detailed study of wavelength tunability of passively Q-switched erbium doped fiber laser using Tin(IV) Oxide (SnO2) as saturable absorber (SA). As a typical n-type semiconductor, ...SnO2 has been widely used in gas sensors, oxidation catalyst, transparent conductor, and electrode materials in solar cell. Herein, we fabricated saturable absorber by compositing SnO2 nanoparticle with polyvinyl alcohol (PVA). The SnO2-SA is incorporated in the laser cavity by sandwiching it between two fiber ferrules. Q-switched laser operation can be continuously tuned from 1521 to 1565 nm, with a wavelength tuning range of up to 45 nm, covering almost the entire C-band. Q-switched pulse parameters such as repetition rate, average power, pulse width, pulse energy, and peak power at different wavelengths were studied in detail. Our experimental results suggest that the SnO2-SA is a suitable and cost-effective solution for broadband tunable laser applications with relatively simple fabrication process.
•Tin(IV) Oxide can operate as wideband saturable absorber, spanning across C-band from 1521 nm to 1565 nm.•The performance of Q-switch EDFL using Tin(IV) Oxide as saturable absorber depends on the lasing wavelength.•Pulse energy at maximum pump power become higher towards longer wavelengths up to 2.6 times.•Repetition rate and pulse width varies from 13.7 kHz to 71.6 kHz and 6.4 s to 2.1 s, respectively.•This experiment verified that pulse energy depends strongly on the repetition rate compared to average power.
