Journal of Russian Laser Research最新文献

We investigate the quantification of entanglement between the photonic and excitonic modes in a semiconductor microcavity injected with squeezed light. By deriving and subsequently establishing the solutions to the quantum Langevin equations, we quantify the transient entanglement and the steady-state entanglement between the photonic and excitonic modes in the low-excitation regime. It turns out that the cavity mode and the exciton mode are entangled in both the weak and strong coupling regimes, and there is the entanglement between the cavity mode and the exciton mode even in the absence of direct coupling between them. Furthermore, though the transit entanglement increases with the squeeze parameter, it decreases with the initial average intensity of the cavity mode. Also, we demonstrate that, in the strong coupling regime, the steady-state entanglement grows with coupling strength while, in the weak coupling regime, it decreases.

In this paper, we propose a numerical calculation model, which considers thermal and gain distribution instabilities and inhomogeneities, for analyzing beam pointing instability in Nd :YAG solid-state lasers. Disturbance factors are defined for pumping power and pumping field, representing their degrees of disturbance. We discuss a numerical example to calculate the beam pointing instability for a positive branch confocal unstable resonator. Subsequently, an optimization design method is discussed for minimizing beam pointing fluctuation in a resonant cavity. This method incorporates considerations of thermal and gain distribution instabilities and inhomogeneities, thus offering a straightforward design approach with broad applicability.

Optical systems, such as a mobile LiDAR system, encounter mechanical disturbances associated with the condition of the road, resulting in significant misalignments in the optical paths within the system. To address this issue, considerable time is dedicated to the realignment process to restart the system. A suggested approach to overcome this challenge involves the implementation of automatic realignment through the control of the motion of the steering mirrors using an advanced control technique known as Model Predictive Control (MPC). This technique, which is relatively new in the field of optics, is widely utilized in the industry due to its capability to manage and resolve a broad range of problems that are inherent to industrial systems, particularly, those that are subject to constraints or undergo disturbances during operation. In this study, we utilize MPC on the optical chain, specifically the LiDAR component, to regulate the beam and promptly rectify any flexure that occurs during both constant and variable trajectories, as well as in the presence of disturbances. A comparative analysis is conducted with the PID controller to evaluate the performance of the advanced technique proposed.

The enumeration of multipartite entanglement is an essential, yet challenging task in quantum information processing. A new measure for calculating genuine tripartite entanglement, called the concurrence fill (CF), has been added to the list of entanglement measures. In this article, we employ the CF to calculate the extent of entanglement present in the three-mode continuous variable states, such as the quasi-GHZ state and quasi-W state. The above mentioned states mimic their respective discrete variable states for moderate coherent strength, while for lower coherent strength, the states are far from possessing maximum entanglement. The photon addition in these states at the single mode and three-mode levels results in the states reaching their respective maximum amount of entanglement even for the lower coherent amplitude. In continuation, a nonlocal tripartite photon addition is implemented on a product three-mode coherent state, and the resultant state is shown to have W-type entanglement.

In this study, we design an ultra-low self-heating radiation long-wave infrared laser communicationoptical system, which mainly includes aperture stop, primary mirror, secondary mirror, three-mirror,field stop, four-mirror, window glass, detector light shield, and image plane. The system enters apupil diameter of 280 mm, a field of view angle of 1×1°, a system focal length of 840 mm, and awavelength of 8 − 12 μmkm; the off-axis four-fold anti-structure is adopted. The optical mirror andstructural components of the material are Aluminum, the system’s own thermal radiation equivalent toa black-body temperature of 171 K. The equivalent black-body temperature of the system is measuredin a vacuum chamber. The temperature of the spacer is 100 – 120 K, the temperature of the coldplate is 85 – 87 K, and the integration time is 550 – 800 μs. At this time, the measured equivalentblack-body radiation temperature of the system is 172.9K; it is consistent with the simulation value.The design scheme solves the technical problems of low signal-to-noise ratio, poor image contrast, andshort detection distance of infrared laser communication system.

We consider the effect of laser shock peening without coating (LSPwC) on the structure and stress state of the AMg6 Aluminum alloy with a thickness from 4 to 14 mm before and after preliminary thermal annealing. The roughness parameters R_a and R_z after LSPwC are determined. The magnitude, depth, and profile of compressive residual stresses (CRS) are found to depend on the thickness of the material and preliminary heat treatment. The layer-by-layer X-ray diffraction analysis shows a correlation between the parameters of the crystal structure and the profile of residual stresses for the processed samples. We find homological distortions of the crystal lattice in the CRS zone and observe the formation of significant (up to - 100 MPa) residual stresses on the unprocessed side of the samples. Also, we determine the surface CRS magnitudes for double unilateral and bilateral processing.

We report on a passively Q-switched 2 μm Ho :YAG ceramic laser, using pure GaAs as a saturable absorber. At an absorbed pump power of 1.28 W, the highest pulse repetition rate, shortest pulse width, largest single pulse energy, and highest peak power are measured to be 295 kHz, 83 ns, 1.49 μJ and 17.95 W, respectively. To the best of our knowledge, this is the first 2 μm passively Q-switched laser with a pure GaAs absorber, the three-photon absorption is believed to play an important role in the saturable absorption process.

We show that by minor modification of the previously proposed procedure for the generation of near-coherent states, one can produce “near states” even from a mixed input state. In this study, we consider this procedure as a conditional quantum-state transformation and find the explicit form of the non-unitary transformation operator. We demonstrate that even in mixed states, this quantum process can produce nonclassical states with a smooth non-positive P-function.