The application of conductive silver elements to polyethylene terephthalate polymer substrates using the laser-induced forward transfer method is considered. By varying parameters such as the energy density of laser radiation and the scanning speed, the optimal regime of applying conductive elements in one stage was found. The maximum value of the conductivity was 0.62 kS/cm. This method has potential applications in various fields, including electronics and sensor technologies.
The behavior of pressure pulses excited in a metal ablated with picosecond laser pulses is analyzed. It is shown that with this effect, the contribution from the thermoacoustic mechanism can exceed the evaporation pressure even when a stationary evaporation regime is established. This pressure behavior differs markedly from that characteristic of the nanosecond regime and is consistent with the obtained experimental data on the monitoring of the recoil pressure under picosecond laser irradiation of lead and aluminum.
We analyze the possibility of a combined use of type II superconductors (both low and high temperature) for noncontact acceleration of a cryogenic fuel target (CFT) located inside a levitating sabot to the required injection velocities (200‒400 m/s) when it is delivered at the focus of an inertial confinement fusion laser facility. We consider CFTs containing a layer of fuel (hydrogen isotopes) in different structural states—from a single crystal to ultra-fine solid phases.
We investigate the prospects for experimentally determining the Sun’s angular momentum by measuring the gravitomagnetic frequency shift of signals exchanged by two satellites in heliocentric orbits. When using modern optical clocks with stability of ∼10–18, the accuracy of such an experiment can reach 5% after 5 years of data accumulation. This is comparable to the accuracy of determining the Sun’s angular momentum using techniques of helioseismology.
We report for the first time, to our knowledge, the discovery of a new nonlinear optical effect in a stimulated Raman scattering (SRS) laser in heavy water as a Raman active medium: a 20-fold local increase in intensity of the backward SRS field up to the optical breakdown threshold (~40 TW/cm2) due to Kerr beam compression as the beam waist moves from bulk water to the surface at a constant pump pulse energy (57 ps, ~2 mJ, and 532 nm). The optical breakdown of water accompanied by ejection of droplets normally to the surface is achieved in a thin layer when the pump beam waist is located at a depth of 1‒3 mm. Outside this layer, the radiation intensity needed to achieve SRS does not exceed 2 TW/cm2. The detected energy concentration in a small volume indicates a high degree of spatiotemporal localization of summed Kerr nonlinear optical contributions to the refractive index and two-photon absorption coefficient, which leads to a local increase in field intensity and to an optical breakdown at a pulse energy 20 times lower than that in the absence of such summation of nonlinear optical contributions.
We report an experimental study of the self-action of TEM01 and TEM00 Gaussian modes in a layer of a comb-shaped amorphous polymer with cyanobiphenyl and azobenzene side fragments. For the linearly polarized TEM01 mode, a pattern of aberration self-action is observed in the form of rings with an additional system of the fringes, caused by interference from two intensity peaks. The position of the fringes and the microscopic image of the deformation region correspond to the local nature of the nonlinear optical response. For the circularly polarized (with an ellipticity of about 7%) TEM00 Gaussian mode, the polarization of the outer aberration ring is close to linear. This effect stems from the self-rotation of the polarization ellipse due to the manifestation of Kerr-type nonlinearity. A characteristic feature of this effect in an amorphous polymer is an increase in the eccentricity of the ellipse (transformation of circular polarization into linear polarization), which is caused by a light-induced change in the orientation distribution function of the chromophores.
We report the development of a combined optical parametric oscillator based on a fan-out MgO:PPLN crystal and a HgGa2S4 crystal, providing smooth wavelength tuning in the spectral range from 2.5 to 10.8 μm. A transversely pumped Nd:YAG laser with a pulse energy of ∼4 mJ and a spatial beam distribution described by a second-order Gaussian function along the x axis and a fourth-order Gaussian function along the y axis is used as a pump source. A maximum achievable radiation energy of the optical parametric oscillator is at a level of 360 μJ for a wavelength of 3.3 μm, 130 μJ for a wavelength of 4.73 μm, and 110 μJ for a wavelength of 7.40 μm. The developed radiation source is used to record absorption spectra of gas mixtures of methane, propane and nitrogen dioxide.
We consider generation of radiation with a comb spectrum in a ring fiber cavity with harmonic mode locking provided by dissipative four-wave mixing. The main element of the laser system cavity is an amplifying one-dimensional photonic crystal, which combines the properties of an intracavity filter and a power amplifier. Using standard propagation equations describing signal conversion in a ring cavity and an output fiber stage, we demonstrate a possibility of employing the proposed model as a broadband frequency comb generator with a controlled repetition rate of generated signals.
We report an experimental implementation of linear absorption spectroscopy using a fiber source of frequency-correlated photon pairs. The object under study is illuminated by a signal beam of a photon pair entangled in frequency. Due to the tight correlation of entangled photons, the absorption spectrum of the object can be measured from the idler beam, counting coincidences in both channels. The main advantages of ghost optics are analyzed, including significant noise reduction due to detecting only paired coincidences and cutting off all single background photons, as well as the potential sensitivity of studying samples, which is especially important when working with biological objects.
The current promising developments in controlled inertial fusion energy (IFE) are aimed at creating a power facility for mass fabrication of cryogenic fuel targets (CFT) and their high rep-rate delivery to the irradiation zone of a powerful laser. To ensure continuous operation of a IFE reactor, the thermonuclear burn region should be refilled with fuel at the rate of about 1 million targets per day. At the same time, handling an array of free-standing CFTs at each step of a closed operation cycle is a key requirement for the reactor technology design. The first step in the CFT fabrication is filling of hollow spherical shells with a fuel, which is deuterium or a deuterium–tritium mixture. The CFT shells are made of polymer, glass, beryllium, or high-density carbon. In world practice, it is customary to carry out the filling step either by diffusion of fuel gas through the CFT shell wall or by injecting liquid fuel through a thin capillary (several microns in diameter) built into the shell wall. The latter method is extremely problematic for future applications because it disrupts the integrity and symmetry of the shell and precludes rep-rate injection of the CFT into the laser focus. Based on data from many experimental runs, we present results on the optimization of a diffusion filling system first developed at the Lebedev Physical Institute (LPI) for filling a batch of free-standing polymer and glass shells (dia. 0.8 to 2.0 mm) with hydrogen isotopes to pressures of 1000 atm at 300 K. These results are unique and have no counterparts in the world.
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