Laser Operations (United States)

Free Space Optical Communication (FSOC) offers secure, line-of-sight, low-latency, high-bandwidth data transmission, yet its practical deployment is significantly challenged by atmospheric turbulence, beam pointing instability, and the need for robust, maintenance-free, high-precision beam steering, particularly in dynamic or mobile environments. Civan Lasers has developed a novel approach to FSOC leveraging Dynamic Beam Lasers (DBL) equipped with electro-optical beam steering and active phase front correction capabilities to reduce these limitations. Unlike conventional static-beam laser systems, DBLs modulate beam position and phase front in real time, enabling precise control of the transmitted beam’s shape, wavefront, and trajectory at MHz rates without mechanical gimbals or moving parts. Experimental ground-to-ground links demonstrate that DBL-enabled terminals stabilize free-space beam propagation, dynamically adapt to turbulence-induced beam wander, and achieve rapid pointing corrections essential for mobile platforms such as drones, aircraft, and satellites, while maintaining high signal integrity, low bit error rate (BER), and high link availability under a wide range of ambient weather conditions.

We present an experimental study on deep-UV (DUV) generation via second harmonic generation (SHG) utilizing a spatially uniform flat-top laser beam as an alternative to the conventional Gaussian beam. A commercial picosecond laser operating at 1064 nm in the TEMoo Gaussian mode was first frequency-doubled in a lithium triborate (LiB₃O₅, LBO) crystal. The resulting SHG beam were then converted into a flat-top profile using a refractive Gaussian-to-flat top beam shaper. This flat-top beam was subsequently frequency-doubled in a cesium lithium borate (CsLiB₆O₁₀, CLBO) crystal to directly generate fourth-harmonic DUV flat-top beams at 266 nm. A comparative experiment between DUV generation using Gaussian and flat-top beams was performed.

This study presents an analytical model to investigate the coupled thermal–dynamic behavior of three-layer sandwich plates designed for large-span sports arenas. The plates consist of a porous functionally graded concrete (FGC) core and graphene oxide powder-reinforced composite (GOP-RC) skins. The formulation is based on the sinusoidal shear deformation theory (SSDT) and solved analytically using Navier’s method, ensuring exact satisfaction of simply supported boundary conditions. The model incorporates porosity effects, GOP dispersion profiles, thermal gradients, and elastic foundation stiffness to capture realistic structural performance. Results reveal that increasing porosity and temperature gradients significantly influence the natural frequencies through combined mass reduction and stiffness variation. The inclusion of GOP markedly enhances thermal stability and bending rigidity, with frequency gains up to 150% under optimal dispersion patterns. Moreover, symmetric pore and reinforcement distributions, thicker facesheets, and Pasternak foundations yield superior vibrational performance. The proposed formulation provides a practical and efficient framework for the design of lightweight, thermally stable, and vibration–resistant concrete panels suitable for modern sports facilities and other large-span structural applications.

Tapered diode lasers, composed of an index-guided ridge waveguide and a gain-guided tapered amplifier, are affected by polarization mismatch between the ridge and tapered sections. Beam quality deterioration is caused by TM high-order modes generated in the ridge section. Under high current injection, these TM modes are further amplified in the tapered section due to polarization mismatch, leading to a decrease in the laser output brightness. In this paper, a combination of deep etching in the ridge section and compressive stress in the tapered section is employed to obtain a fundamental mode seed source with a high TE degree of polarization (DOP), simultaneously improving the polarization match between the ridge and tapered sections. The fabricated tapered diode laser achieves a beam quality factor of M2(1/e2) = 1.2 at an output power of 11.57 W. The peak electro-optical efficiency is 59.8%, and the maximum output brightness reaches 936 MW·cm-2·sr-1.

To compare the outcomes of the Tecnis Eyhance ICB00 IOL, designed to enhance intermediate vision, to a conventional Tecnis Monofocal ZCB00 IOL. This retrospective analysis compared two cohorts of patients undergoing lens replacement surgery with bilateral implantation of the Tecnis ICB00 or the Tecnis ZCB00 IOL (383 patients in each group). Monocular and binocular uncorrected distance (UDVA), intermediate (UIVA; 66cm), and near (UNVA; 40cm) visual acuities, refractive predictability, and patient-reported outcomes were compared. A sub-analysis of patients with the Eyhance IOL was performed to compare patients who achieved bilateral emmetropia to those with mini-monovision. One-month postoperative outcomes were analyzed. Both groups had comparable UDVA outcomes. On average, both monocular and binocular UIVAs were approximately one Snellen line better in patients implanted with Eyhance IOL (monocular UIVA: ICB00 0.23 ± 0.18 logMAR, ZCB00 0.33 ± 0.19 logMAR; binocular UIVA: ICB00 0.18 ± 0.18 logMAR, ZCB00 0.26 ± 0.20 logMAR, p < 0.01). Likewise, the mean UNVA was also one Snellen line better with the ICB00 model (monocular UNVA: ICB00 0.51 ± 0.20 logMAR, ZCB00 0.61 ± 0.18 logMAR; binocular UNVA: ICB00 0.42 ± 0.19 logMAR, ZCB00 0.51 ± 0.22 logMAR, p < 0.01). There was no difference between the two groups in overall satisfaction or visual phenomena. A subgroup of patients who achieved mini-monovision with Eyhance IOL had, on average, one Snellen line better UIVA and UNVA compared to patients with bilateral emmetropia. Patients receiving the enhanced monofocal IOL had better intermediate and near vision compared to those receiving the conventional monofocal IOL, with similar levels of patient-reported photic phenomena in both groups.

We demonstrate a 1.7 µm femtosecond Tm-doped fiber laser system featuring an all-polarization-maintaining architecture. The seed oscillator is mode-locked by carbon nanotubes and delivers stable pulse centered at 1787.6 nm. With two backward pumped amplifiers, the average power of the laser is amplified to ∼458 mW. Employing proper dispersion management in an all-fiber chirped pulse amplification scheme and the soliton compression effect, we obtained a femtosecond pulse of 206 fs with a pulse energy of 8.8 nJ at a repetition rate of ∼52 MHz. To the best of our knowledge, this is the first demonstration of 1.7 µm femtosecond laser based on a thulium-doped oscillator with all-polarization-maintaining architecture.

Environmental concerns and issues are raised regarding Portland cement manufacturing. Besides, mortar and concrete deterioration is a very common problem. Therefore, eco-cement is an efficient alternative to Portland cement. Eco-cement is an environmentally friendly green building-material having self-healing abilities to remediate concrete cracks. In this study, eco-cement was produced from the ash of agricultural crops residues (pyrolysis of rice straw, sawdust of forest residues, and corn stover) which are hypothesized to enhance the binding abilities among the different components of cementitious materials (residues ash, cement, sand, and bacteria) and accelerate the biomineralization process to precipitate calcite and seal the concrete cracks. Through this study, 12 experiments (4 treatments in triplicates) were conducted. The resultant eco-cement was used to prepare mortar cubes which were tested and analyzed. The following engineering properties of the resultant eco-cement mortar cubes were investigated: compressive strength, four point bending test, and water absorption test. The results show that the addition of rice straw ash delivered the highest compressive strength and the highest four-point-bending of eco-cement mortar cubes average of 86.33 kN and 2.18 kN, respectively; and an acceptable water absorption (5.82%) compared to all other treatments. The energy dispersive X-ray (EDX) analysis test results of the rice straw ash, sawdust ash and corn cob ash according to mass% of Si element were 7.55, 0.93 and 3.13 respectively and 0.84%, 0.45% and 0.41% for Al, respectively. It was concluded that the addition of the ash of agricultural crop residues to the cementitious mixture enhances its properties, where the resulting eco-cement is a promising substitute of the conventional Portland cement.

Long time being used in Datacom, in computer mice and cell phone, last decade VCSEL developments show that this laser source is an alternative to the long established edge emitter laser diodes (EELD), with attractive high power performance, better reliability, lower manufacturing costs and design flexibility. This paper will discuss the benefits of VCSEL compared to EELD and the importance to minimize parasitic inductance when used in LiDAR application were short pulses, high peak power are required1. A theoretical analysis will be presented to show the advantage of multijunction VCSEL with better Power Conversion Efficiency (PCE) and Brightness than single junction VCSEL.

III–V ternary alloy quantum-wells have become a hot topic in recent years. Especially, GaAs/GaAsSb quantum wells have attracted increasing attention due to their numerous applications in the field of near-infrared optoelectronic devices. With the further reduction of dimensions, GaAs/GaAsSb nanowires show many special properties compared to their quantum well structures. In this work, GaAs/GaAs1−xSbx/GaAs coaxial single quantum-well nanowires with different Sb composition were grown by molecular beam epitaxy. The band structure and the optical properties were investigated through power-dependent and temperature-dependent photoluminescence measurement. It has been found that a deeper quantum well is created with the increase of Sb component. Thanks to the deeper quantum well, more effective electron confinement has been realized, the emission from the sample can still be detected up to room temperature. The different trend of peak position and shape at various temperatures also supports the improved temperature stability of the samples. These results will be beneficial for the design of alloy quantum wells, and will facilitate the development of alloy quantum-well based devices.

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