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 control the optical comb in Nd:YVO<sub>4</sub> mode-locked lasers with intracavity frequency doubling based on KTP crystals via changing the cavity length and its dispersion properties and achieve high-purity radiofrequency (RF) signals. The laser output wavelength (532 nm) is in the range of the molecular iodine absorption spectrum with narrow (1.5 kHz) homogeneously broadened lines. We propose to stabilize the two longitudinal modes on two narrow iodine absorption lines. The third derivative of the absorption line could be obtained by heterodyning the absorption signal with the third harmonic of the modulation signal. The resulting RF error signal could be used to stabilize two locked longitudinal modes separated by 1.37 GHz which results in stabilized beat note signal.
We present a new TOF camera design based on a compact actively Q-switched diode pumped solid-state laser operating in 1.5 μm range and a receiver system based on a short wave infrared InGaAs PIN diodes focal plane array with an image intensifier and a special readout integration circuit. The compact camera is capable of depth imaging up to 4 kilometers with 10 frame/s and 1.2 m error. The camera could be applied for airborne and space geodesy location and navigation.
Identifying methane anomalies responsible for the temperature increase, by hiking trails in the Arctic requires great human labor. It is necessary to use lidar methods for search and identification of methane from permafrost. Necessary to create a Raman lidar for monitoring of emissions of methane hydrate from the permafrost. Hyperspectral resolution would resolve the isotope shifts in the Stokes spectra, thereby to determine the isotopic composition of methane ratio C<sup>14</sup>/C<sup>12</sup> CH<sub>4 </sub>carbon emissions and identify the source for study (permafrost or oil deposits)
The experimental results presented in this study focused on the study of biological processes caused by exposure to the coating layers of the laser green light seed (λ = 532 nm) range for the larch, violet (λ = 405 nm) and red (λ = 640 nm) for spruce. Spend a series of experiments to study the dependence of crop seed quality (spruce and larch from the pine family) from exposure to laser radiation under different conditions. In all the analyzed groups studied seed germination and growth of seedlings exposed to laser exposure, compared with the control group. The results showed that the higher percentage of germination than seeds of the control group.
We report on theoretical investigation of quasi-three level Er:YAG laser. We propose a numerical model of the laser design with side pump by 1471 nm laser diodes. The model describes the dynamical propagation of the pump in the cavity and the kinetic parameters of the active medium.
Experimental results presented in this study tends to explore viruses in the water for their further decontamination under the influence of laser radiation (λ=220-390 nm). Conducted a series of experiments to study the dependence of water quality from the effects of laser radiation. Correlation between degree of survival of viruses and power density. The results showed that all the analyzed samples of water is clearing from bacteria to 98%. Preliminary tests of the prototype laboratory system UFOVI has opened up new opportunities for water sterilizing.
We propose a Rayleigh-Sommerfeld based method for numerical calculation of multiple tilted apertures near and far field diffraction patterns. Method is based on iterative procedure of fast Fourier transform based circular convolution of the initial field complex amplitudes distribution and impulse response function modified in order to account aperture and observation planes mutual tilt. The method is computationally efficient and has good accordance with the results of experimental diffraction patterns and can be applied for analysis of spatial noises occurring in master oscillator power amplifier laser systems. The example of diffraction simulation for a Phobos-Ground laser rangefinder amplifier 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 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 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.
We demonstrate a new approach to designing a compact RF standard based on the transfer of frequency stability of
hyperfine transitions in molecular iodine to the stability of a laser cavity length. We use frequency doubled Nd:YVO<sub>4</sub>
laser operating in Kerr lens mode-locked regime and frequency lock it to hyperfine transitions in molecular iodine with
further detecting the beat note signal between longitudinal modes on a fast photodiode. A similar system is used for
estimating the standard Allan deviation of RF signal which is 2.1 x 10<sup>-14</sup> at the time 100 s.