5 kHz, 4.2mJ, 900 ps end-pumped Nd:YVO MOPA laser system.

A 5 kHz sub-nanosecond master oscillator power amplifier (MOPA) laser system was reported in this paper. The master oscillator was an electro-optically Q-switched Nd:YVO laser directly pumped at 879 nm, yielding a pulse energy of 520 µJ and a pulse width of 900 ps at 5 kHz. With two Nd:YVO amplifiers directly pumped at 914 nm, the pulse energy was further scaled up.

Building roof extraction from ASTIL echo images applying OSA-YOLOv5s.

Light detection and ranging (LiDAR) is a type of essential tool for urban planning and geoinformation extraction. Airborne streak tube imaging LiDAR (ASTIL) is a new system with great advantages in the rapid collection of remote sensing data. To the best of our knowledge, a new method to extract a building roof from the echo images of ASTIL is proposed.

Generation and amplification of a multi-beam sub-nanosecond laser.

In this paper, a methodology to produce a multi-beam sub-nanosecond laser is proposed. Laser pulses with a pulse energy of 0.14 mJ and a pulse width of 490 ps are generated in a YAG/Nd:YAG/Cr:YAG microchip laser at a repetition rate of 200 Hz.

High-pulse-energy passively Q-switched sub-nanosecond MOPA laser system operating at kHz level.

A passively Q-switched sub-nanosecond master oscillator power amplifier (MOPA) laser system at 1064 nm has been reported in this paper. The master oscillator was a passively Q-switched YAG/Nd:YAG/Cr:YAG microchip laser, yielding a pulse energy of 0.14 mJ and a pulse width of ∼490 ps at repetition rates of 500 Hz and 1 kHz.

Temporal Multilevel Luminescence Anticounterfeiting through Scattering Media.

Optical anticounterfeiting, typically using luminescent materials to encode and unveil hidden patterns, plays an essential role in countering fraud in trademark, document security, food industry, and public safety. However, this technique is often realized through color-encoded fashion and in the visible range, preventing high-order encryption as well as visualization through scattering layers. Here, we describe a set of shortwave infrared (SWIR)-emitting lanthanide-doped nanoparticles with precisely controlled luminescence lifetime, which can be utilized as temporary codes for multilevel anticounterfeiting through opaque layers.

Voxel-based spatial elongation filtering method for airborne single-photon LiDAR data.

A novel voxel-based spatial elongation filtering method is proposed, to reduce noise in airborne single-photon lidar (SPL) data. In this method, six additional points are generated adjacent to each point of interest in the SPL data. Then, we count the number of points within each voxel and discriminate signals from noise via a predefined threshold.

Deblurring streak image of streak tube imaging lidar using Wiener deconvolution filter.

We use a Wiener deconvolution filter to deblur the streak image of streak tube imaging lidar to improve the spatial resolution of the system and reduce the edge blurring effect in point clouds. Experiments were performed to investigate the performance of the deconvolution method. Results show that the spatial resolution improved from 9 to 4.

14 GHz broadband and continuously frequency-tuned Nd:YVO laser with an RTP etalon.

A laser-diode-pumped broadband and continuously frequency-tuned all-solid-state Nd:YVO laser at 1064 nm with an output power of 200 mW is demonstrated. A RbTiOPO (RTP) etalon and a piezoelectric-transducer (PZT) are utilized for coarse and fine frequency tuning, respectively. Dependence of the frequency excursion on the applied voltage to the RTP etalon and the displacement of the PZT is theoretically and experimentally investigated.

Impact of input field characteristics on vibrational femtosecond coherent anti-Stokes Raman scattering thermometry.

In this paper, three ultrashort-pulse coherent anti-Stokes Raman scattering (CARS) thermometry approaches are summarized with a theoretical time-domain model. The difference between the approaches can be attributed to variations in the input field characteristics of the time-domain model. That is, all three approaches of ultrashort-pulse (CARS) thermometry can be simulated with the unified model by only changing the input fields features.

Linearly frequency-tuned LD-pumped Nd:YVO laser with an 18-GHz broadband tuning range.

A continuously frequency-tuned laser diode end-pumped Nd:YVO laser at 1064 nm is demonstrated. A coated etalon and a piezoelectric-transducer (PZT) are utilized for coarse and fine frequency tuning, respectively. Broadband and linear frequency tuning without mode hops is conducted by the synchronous adjustment of the etalon and the PZT.

2.4 THz/s continuously linearly frequency-modulated Nd:YVO laser.

We demonstrate a linearly frequency-modulated laser from a laser diode (LD) pumped Nd:YVO laser. A fast frequency tuning of 2.40 THz/s with a tuning range of 6 GHz is achieved in LD pumped Nd:YVO 1064 nm laser by using RbTiOPO (RTP) crystals as the frequency modulator.

Heterogeneous core/shell fluoride nanocrystals with enhanced upconversion photoluminescence for in vivo bioimaging.

We report on heterogeneous core/shell CaF2:Yb(3+)/Ho(3+)@NaGdF4 nanocrystals of 17 nm with efficient upconversion (UC) photoluminescence (PL) for in vivo bioimaging. Monodisperse core/shell nanostructures were synthesized using a seed-mediated growth process involving two quite different approaches of liquid-solid-solution and thermal decomposition. They exhibit green emission with a sharp band around 540 nm when excited at ∼980 nm, which is about 39 times brighter than the core CaF2:Yb(3+)/Ho(3+) nanoparticles.

High-repetition-rate and short-pulse-width electro-optical cavity-dumped YVO₄/Nd:GdVO₄ laser.

In this paper, an electro-optical cavity-dumped 1.06 μm laser using YVO4/Nd:GdVO4 composite crystal under 808 nm diode-laser pumping was reported. Theoretical calculations showed that the temperature distribution in YVO4/Nd:GdVO4 crystal was lower than that in GdVO4/Nd:GdVO4 and Nd:GdVO4 crystals under the same conditions.

Laser induced spark ignition of coaxial methane/oxygen/nitrogen diffusion flames.

We report the laser induced spark ignition (LSI) of coaxial methane/oxygen/nitrogen diffusion flames using the 1064 nm output of a Q-switched Nd:YAG laser. The minimum ignition energy (MIE) and ignition time of the LSI has been determined by measuring the emission signals due to the ignited flames. The effects of the gas mixture properties, including the overall equivalence ratio (Ф), oxygen concentration and flow rate, and the ignition positions on the two parameters have been investigated systematically.

Laser ablation ignition of premixed methane and oxygen-enriched air mixtures using a tantalum target.

We report the laser ablation ignition of premixed methane and oxygen-enriched air mixtures using a tantalum target. The minimum laser pulse energy (MPE) of the ablation ignition was obtained as 2-4 mJ, which was reduced by one order of magnitude compared with that of the direct laser-induced gas breakdown ignition. The ignition time of the ablation ignition was investigated for the first time, to our best knowledge, by measuring the emission signal profiles due to the successfully ignited flames, and an ignition time as short as ~50 μs was obtained.

Intense ultraviolet upconversion emission from water-dispersed colloidal YF3:Yb3+/Tm3+ rhombic nanodisks.

Intense ultraviolet upconversion emission has been observed in water-dispersed uniform rhombic nanodisks (side length of ~14 nm and thickness of ~2.5 nm) of YF3 co-doped with Yb(3+) sensitizer and Tm(3+) activator ions, when excited at ~980 nm.

Tuning the size and shape of colloidal cerium oxide nanocrystals through lanthanide doping.

We present a simple method to gradually tune the size and to induce the shape change of CeO(2) nanoparticles via increasing the content of Yb(3+) doping.

Comparison on performance of passively Q-switched laser properties of continuous-grown composite GdVO4/Nd:GdVO4 and YVO4/Nd:YVO4 crystals under direct pumping.

The comparison on performance of passively Q-switched laser properties of continuous-grown composite GdVO(4)/Nd:GdVO(4) and YVO(4)/Nd:YVO(4) crystals under direct pumping to the emitting level was demonstrated. A Cr(4+):YAG crystal was used as saturable absorber. At an incident pump power of 10 W, the average output power, the pulse width, the repetition rate, the pulse energy, and the peak power for a GdVO(4)/Nd:GdVO(4) laser were 1.

Tunable solid-state laser based on modified polymethyl methacrylate with methanol doped with Pyrromethene 580.

Solid-state dye material was fabricated by doping a laser dye Pyrromethene 580 (PM580) into the polymer host polymethyl methacrylate. Methanol was also injected into the host to improve the optical properties. The broadband and narrowband laser performances of the sample were studied in this paper.

Calculations of laser induced dipole-quadrupole collisional energy transfer in Sr-Ca.

A three-state model for calculating the cross section of laser-induced dipole-quadrupole collisional energy transfer in Sr-Ca system is presented. The motion equations for the probability amplitudes of the three intermediate states are obtained. The expression of the cross section is derived.

[Study of the effect of light source stability on the signal to noise ratio in degenerate four wave mixing experiment].

The effects of the stability of dye laser on the signal to noise ratio in degenerate four-wave mixing (DFWM) were first investigated in iodine vapor using forward geometries. Frequency-doubled outputs from a multi-mode Nd : YAG laser pumped dye laser with laser dye PM580 dissolved in ethanol was used. With the help of forward compensated beam-split technique and imaging detecting system, the saturation intensity of DFWM spectrum in the iodine vapor at 5 554.