We model output characteristics of the 1645 nm 8 mJ 10 ns 100 Hz Q-switched Er:YAG DPSSL. The laser is end pumped at a wavelength of 1532 nm. Fiber-coupled diode laser module was 10 nm FWHM, 12 W CW, 200 μm, NA 0.22. Various tapering of the active rod has been considered for 1 mm diameter, 20 mm long and 0.5% Er doping. We discuss the heat deposition process, the energy storage efficiency and the average power limitations for Q-switched regime of generation and amplification, and find the system scalable for the high power operation.
We demonstrate a pulse-bursting phenomenon in Yb:Er glass laser operating at 1.54 μm. Glass-ceramic material with a low value of saturation threshold based on Co<sup>2+</sup>:β-ZnSiO<sub>4</sub> nanocrystals was used as a passive gate for pulse-burst operation. The bursts of pulses were 1.5 ms long, each burst consisted of 40-55 pulses with 9-30 μJ energy per pulse and 0.2-3 μs pulse width. Bursting outputs arise via a coupling between slow switching arising via a slow pump modulation and fast pulsations resulting from Q-switch mechanism. We show that absorption cross-section strongly affects the mode of laser operation ranging from relaxation oscillations corresponding to low cross-section values to bursting and conventional Q-switch operation in the case of their higher values.
We report on the passive Q-switching of a compact diode-side-pumped Er,Yb:glass laser by a novel saturable absorber (SA) based on transparent glass-ceramics (GC) containing Co<sup>2+</sup>Mg(Al,Ga)<sub>2</sub>O<sub>4</sub> nanocrystals. To prepare the GC, an initial magnesium aluminosilicate glass doped with Ga<sub>2</sub>O<sub>3</sub> containing 0.1 mol% CoO was synthesized by a conventional melt-quenching technique and heat-treated at 850–950 °C. The X-ray diffraction analysis of the GC confirmed the precipitation of Co<sup>2+</sup>Mg(Al,Ga)<sub>2</sub>O<sub>4</sub> crystals with spinel structure (6-7 nm in size). Depending on the heat-treatment temperature, the saturation intensity for the GC measured at 1540 nm was in the 0.5...0.7 J/cm<sup>2</sup> range and the recovery time was in the 240...335 ns range. Using the SA based on GC prepared by the heat-treatment at 950 °C with an initial transmission of 84.7%, we generated stable Q-switched pulses 1.14 mJ in energy and 7.2 ns in duration. The peak power reached 160 kW, the repetition rate was 1 Hz and the laser wavelength was 1535 nm. The developed GCs are promising for Q-switching of erbium lasers emitting at 1.5-1.7 μm.
We demonstrate a durable and efficient 3 mJ 10 ns 100 Hz Nd:YAG laser developed with a view to the space borne operation. We discuss the cavity construction design principle, the approach to high efficiency and the smooth pulse operation. The experimental investigation for the best pair of Q-switch transmission and output coupler reflection coefficient is considered. The factors influencing the pulse shape are analyzed. The 100 Hz operation with good beam quality is demonstrated.
We demonstrate side pumped ultra-compact Q-switched Er:glass laser for rangefinding with 1.4 mJ energy at 1.54 um. Laser diode with 75 W power and 5 ms pulse duration was used. Active medium was enveloped with diffuse reflector. Output pulse energy in free-running mode was 27 mJ with a slope efficiency of 12%. Transparent glass-ceramics containing Co2+:MgAl2O4 nanocrystals were used as a passive gate to ensure Q-switching in an operation temperature range and transverse mode selection. The Q-switch mode had steady operation at 1 Hz repetition rate with thermal effects playing no visible role.
We demonstrate a compact Er:glass single-rod fiber laser for rangefinding with 1 mJ energy Q-switched at 1.54μm.
Double-pass pumping with 16 W power and 5 ms pulse duration was used. Active medium was enveloped with diffuse
reflector. Thus efficient output power operation achieved. Free-running mode output pulse energy was 12 mJ with a
slope efficiency of 16%. Transparent glass-ceramics containing Co<sub>2</sub>+:MgAl<sub>2</sub>O<sub>4</sub> nanocrystals were selected as the optimal
passive gate to ensure Q-switching in a temperature range and transverse mode selection. The Q-switch mode had steady
operation at 1 Hz repetition rate with thermal effects playing no visible role.
We experimentally study passive mode-locking in Nd:YVO<sub>4</sub> laser based on second harmonic generation in KTP crystal.
We characterized RF spectra and optical spectra versus pump power, the KTP crystal temperature and position, the
output coupler reflectivity, and the intracavity polarizer. We discuss the device performance considering cascaded χ<sup>(2)</sup>
lensing in KTP, frequency doubling nonlinearity, and Kerr lens formed in Nd:YVO4. Implementing an intracavity Lyot
filter and cavity length modulation via PZT does not affect mode-locking capability. These results and ultra-low noise
mode beat signal open a new perspective for stable RF signal generation by transferring optical reference stability
(iodine absorption lines) into RF domain.