Laser Technology Research Articles

High-precision wavelength measurement using a virtual Fizeau cavity

Fizeau wavelength measurement plays an important role in the fields of laser technology, optical communication, and optical metrology. The accuracy of the traditional multistage Fizeau wavemeter is limited owing to the degradation of the stripe symmetry and finesse caused by variations in the cavity length. Herein, we propose a virtual Fizeau cavity (VFC) based on the principle of phase difference to address this issue. The principle analysis and simulation of this measurement system are presented, along with experiments that verified the feasibility and performance of the VFC method. The wavelength measurement accuracy of this system is superior to 60 MHz in the 350–1100 nm wavelength range. The design concept of “virtual–real combined” cavities first proposed in this paper to our knowledge introduces possibilities for the development of high-accuracy Fizeau wavelength measurements.

Enhanced Characterisation Studies and Synthesis of Undoped and Copper Doped-Organic Nonlinear Optical Single Crystal: L-Alanine Aluminium Nitrate

Single crystals of untreated and copper (Cu2+) metal ion-doped L-alanine aluminium nitrate (LAAN), a room-temperature slow evaporation organic nonlinear optical material. Single crystals were studied for structural, spectral, optical, hardness, secondorder non-linear optical, electrical [(alternating current (AC) and direct current (DC)], and photoconductivity properties as they grew. Crystallinity, monoclinic structure with space collection P21, and lattice specifications were deliberate using single crystal X-ray diffraction investigation. The existence of functional clusters is revealed by the spectral properties, and the means of vibration of various molecular clusters existing in LAAN were evaluated using Fourier transform infrared (FTIR). The low cut-off wavelength and transmittance properties were determined using optical analysis. The band gap energy of LAAN and Cu-doped LAAN crystals was estimated to be 3.40 eV and 2.70 eV, respectively, using the Tauc plot. It was revealed that pure crystals had a lower dielectric constant than crystals that had been doped with copper. After doping with rising temperatures, AC conductivity started to rise. With the use of the Kurtz and Perry approach, the effectiveness of the grown crystal’s second harmonic generation was computed, Cu-doped LAAN was discovered to be 3.3 times more prominent than potassium dihydrogen phosphate (KDP) and 2.2 times more prominent than pure LAAN crystals. The nonlinear optical characteristics of LAAN crystals have therefore been improved by copper doping. It is most suited for use in electro-optic applications like laser technology, telecommunications and optical signal processing because of its negative photoconductivity.

Ultrafast Laser Fabrication of Microchannels on Aluminium Alloy Substrate

Aluminium alloy 6061 has a versatile application within industrial heat exchangers, heat sinks, chemical equipment, and frames of aircraft and ships. Its physical and mechanical properties such as lightweight, high strength, corrosion resistance, and thermal and electrical conductivity make it a suitable material choice for these applications. Within thermal and micro-electromechanical applications, such as heat exchanges, radiators, and heat sinks used in microelectronics, the dissipation of heat plays an important role. For optimum heat dissipation, a higher surface area is required. This can be achieved by modifying the surface by fabricating microchannels. A number of processing techniques are used for fabricating microchannels on different materials. A laser is a flexible non-contact machining tool that may be used to create any profile or contour on practically any material. In recent times due to the advancement in laser technology, the use of ultrafast laser material processing is one potential route toward further extending the fabrication of high-quality microchannels without defects caused due to heat-affected zones and in a sustainable manner. In this paper, we present an experimental work of fabrication of microchannels on an aluminium alloy 6061 surfaces by using a low power (<4 W) 400 fs laser system. The dimensional accuracy of the fabricated microchannels is assessed using scanning electron microscopy and 3D profilometry. Furthermore, as processing speed and scale is of importance in industrial laser processes, the use of scanning optics is examined as a means of developing a rapid and scalable ultrafast laser process.

Comprehensive study of synergistic effects of phase separation structures and electric fields for enhancing the heat transfer performance of minichannel heat sinks

In this paper, the effects of the phase separation structure on the enhanced boiling heat transfer mechanism and bubble dynamics were investigated. Two types of phase-separation structures and one type of conventional minichannel were manufactured by ultrafast laser technology. Flow boiling experiments of a glycerol-water solution were conducted under various heat flux and electric field conditions. Entropy generation analysis was employed to comprehensively analyze and assess energy losses and irreversibility within the system. Response surface analysis method was introduced to optimize operational and design parameters for achieving optimal experimental design. Moreover, the coupling effect of the phase-separation structure and electric field was observed to have a significant impact on the enhancement of heat transfer. The visualization results indicate that, compared to conventional parallel minichannels, the countercurrent minichannel with phase-separation structure leads to a gradual decrease in the aspect ratio of confined bubbles downstream (in contrast to the increasing aspect ratio of confined bubbles downstream in general minichannels), and smaller bubbles at the upstream of adjacent minichannels gradually disappear and diminish due to the condensation effect. The experimental results demonstrate that the porous phase-separation structure plays a significant role in enhancing heat transfer performance and can reduce the increase of two-phase friction pressure drop per unit length with the increase of heat flux. Under electric field-free conditions, the porous phase separation structure exhibits a maximum increase in heat transfer efficiency of 26.2% compared to conventional structures. Furthermore, the maximum reduction in two-phase frictional pressure drop per unit length reaches 19.4%. In the presence of the synergistic effect between an electric field and the phase separation structure, the maximum heat transfer efficiency is enhanced by 65.5%. The above analysis provides an effective means for investigating the comprehensive performance of phase separation structures and the bubble dynamics of confined bubbles in heat sinks.

Use and Future Development of Optical Measurement Technology in the Study of Wood Surface Roughness CiteSpace-Based Scientometric Analysis (2003 through 2022)

Abstract Although the contact probe measurement technique is excellent for wood surface roughness measurement, it is necessary to reevaluate the advantages and future development direction of optical measurement techniques in this field, given the emergence of optical measurement techniques such as laser technology and the increasing academic interest in wood surface roughness. The traditional review method, due to its rather limited research directions, only provides a macroscopic and qualitative description of certain laws and conclusions. The purpose of this review is to use the bibliometrics theory and method to comprehensively sort out the research hot spots in this field and explore them in depth.

The Correlation between the Structures of Bimetallic Tartrate Complexes in Solutions for Laser-induced Synthesis and Sensor Characteristics of Microbiosensors Materials

Background: Determination of diagnostically significant components of biological ma-terials using enzyme-free microscopic sensors is an urgent scientific task, which is being worked on by a significant number of scientific groups in the world. This is due to the fact that microscop-ic sensor-active tracks on inert surfaces can be obtained without preliminary manufacturing of precision templates. Methods: Laser Induced Chemical Liquid Phase Deposition (LCLD) is a laser technology that al-lows the deposition of microsized conductive tracks from aqueous solutions of transition metal compounds at the focus of a laser beam. These tracks can be formed by one or two metals at the same time. The possibility of obtaining complexes in solution in which two different metals inter-act with one common coordination sphere of the ligand is of particular interest. The structure of such complexes is still insufficiently studied. Results: The present study supplements the missing information on tartaric acid complexes, which can simultaneously coordinate two metals, for example, copper, nickel, silver, iron, and cobalt. Heterophase LCLD demonstrates high sensory activity in the electrochemical oxidation/reduction of glucose and hydrogen peroxide. Bimetallic deposits can be obtained in two ways. The first method consists of successive precipitation from a solution containing an ion of one metal, then another on top of the first. The second way is to create a solution in which two metals and one lig-and are simultaneously present. Laser deposition is carried out in one stage. In practice, the possi-bility of the second method is not always realized. Conclusion: In the present work, the basic principles of the formation of heterophase bimetallic sensor-sensitive porous material with a highly developed surface under the action of laser radia-tion have been analyzed, and new reference data have been accumulated on the structure of tar-trate complexes containing two metals.

Drones in fish fauna assessment of rivers

The purpose of the study was to develop the method of using unmanned aerial vehicles (drones) to map fish fauna habitats in a large lowland river. The intention was to acquire and process spatial data to implement it in the Mesohabitat Simulation system (MesoHABSIM).At three different water levels, remote sensing data was acquired by unmanned aerial vehicles on the lower Vistula River section. In parallel, depths and velocities of flowing water were measured. Orthophotomosaics were created from the collected images, overlaid with depth and velocity observations to identify hydromorphological units. Maps of fish fauna habitats under different water levels were obtained. The application of the developed procedure algorithm proved successful in habitat mapping studies on a large, deep river with opaque water. The significance of using orthophotomosaics presenting the river under well-defined flow conditions was proven to achieve high accuracy in mapping habitat conditions and reduce errors in habitat usability analyses by fish community.The superiority of using unmanned aerial vehicles over other methods of collecting data on river habitats and depth and velocity measurements using the Acoustic Doppler Current Profiler (ADCP) method in large rivers with non-clarity water was confirmed. In addition, it was pointed out that drones provide high-resolution images under well-defined flow conditions, which are impossible to obtain using available cartographic materials. The validity of using the incomparably cheaper ADCP technology relative to laser technology, whose application in rivers with opaque water is very complicated, was also confirmed.

SMaC sets new standards in coating and surface finishing

AbstractThe Fraunhofer Institute for Laser Technology ILT has developed SMaC, a coating process that combines extreme high‐speed laser material deposition (EHLA) and mechanical post‐machining in a single process. Thanks to SMaC, high‐strength coating materials can be applied quickly and efficiently, and simultaneously finished by machining.

Laser Based Short Range Multipurpose Security System

Abstract: This paper presents an IoT-based Laser Security System (IoT-LSS) designed to enhance perimeter security and intrusion detection capabilities. Traditional security systems often rely on cameras and motion sensors, which can be susceptible to false alarms and environmental limitations. The proposed IoT-LSS addresses these challenges by leveraging laser technology, IoT devices The interruption of the laser beam caused by an intruder's movement triggers an alert. IoT integrated with the laser pairs collect real-time data and transmit it to a central control unit. This control unit acts as the brain of the system, making intelligent decisions based on the incoming data stream. Control unit identifies object and differentiation between human movement and other environmental disturbances. The implementation of the IoT LSS demonstrates its effectiveness in reducing false alarms and providing reliable intrusion detection. The fusion of IoT and laser technology not only enhances security but also minimizes maintenance efforts compared to traditional systems. By harnessing the power of IoT, laser technology, the proposed Laser Security System showcases a promising solution for modern security challenges, contributing to a safer and more connected world.

Research on the ultrafast laser in microscopy

Ultrafast laser technology has been making a huge difference in different areas, such as material processing, laser surgery, and military usage. In parallel with the development of ultrafast lasers, microscopy also greatly promotes modern science, even though there are still some shortcomings, and one of them is that it is hard to obtain information about dynamic samples. However, this shortcoming can be solved by using ultrafast laser technology. This review will introduce the concept of ultrafast laser technology and electron microscopy, while several limitations of conventional electron microscopy will be mentioned. This paper also introduces two advanced technology in ultrafast microscopy. Nowadays, by taking advantage of ultrafast laser technology, the dynamic sample can be observed with highly improved temporal resolutions, which are basically restricted by the duration of pulses, but the ultrafast laser technology makes the duration even reach the range of attoseconds. However, there are some limitations, such as aberration, still hamper the development of high spatial resolution in microscopy. It is hoped that the ultrafast microscopy will break through the bottleneck of traditional microscopy in the future.

Analysis and Reduction of Nonlinear Effects in Optical Fiber Frequency Transfer

Nonlinear effects in optical fiber frequency transfer have a significant impact on the precision of frequency transfer. We investigate the main nonlinear effects, including the Brillouin scattering and the Raman scattering, in optical fiber frequency transfer through theoretical and simulation calculations in detail. The calculation results show that the threshold powers of the Brillouin scattering and the Raman scattering decrease with the increase in the fiber length; however, the fiber length has little to no impact on the threshold powers when the fiber length is greater than 10 km. The threshold powers, including the Brillouin scattering and the Raman scattering, increase as the attenuation coefficient increases. Conversely, when it comes to the gain coefficients, the outcomes exhibit a reverse trend. When the linewidth Δvlaser of the laser source is from 1 Hz to 1 MHz, the linewidth Δvlaser does not affect the threshold powers of the Brillouin scattering. This study seeks to offer design guidance aimed at mitigating nonlinear effects in optical fiber frequency transfer. The calculated results hold considerable potential in guiding various applications reliant on Brillouin and Raman scattering properties, such as laser technology and optical fiber sensing.

Modelling optimal water retention in hydrogenic habitats using LIDAR laser data

Degradation of hydrogenic habitats in climate change increased rapidly. It is important that we take actions to stop this process. Solution is to increase efficiency of water usage by ecosystems - especially water based ones. Building devices for delaying surface water runoff – like locks and dams – should improve hydrogenic habitats conditions and allow surrounding ecosystems use rainwater more efficient. Modelling of small retention in forests is an important aspect in decision making schema. Aim of this paper is to point optimal solutions for height and placement of devices which delay surface water runoff to set necessary water table level for renaturalization and maintenance of degrading natural habitats. Data used for analyses were acquired in the Polanów Forest Inspectorate in West Pomeranian voivodeship because of the topography diversification and the drainage infrastructure presence. There were three research plots selected based on decreased stability of habitats and historic data stated that there were natural water reservoirs, which were drained in past. Based on 2012 LiDAR (Light Detection and Ranging) point cloud the digital terrain model (DTM) was built. Water outflow points – melioration canals – were identified and analysed for optimal device localization. In following part of research specific data for each hydrogenic habitat were used to model height of devices which delay surface water runoff. Optimal level of device and area covered by water were set for each site separately. The results were handed over to the investor for implementation, then the compliance of the assumptions of the simulation of raising the water table with the as-built field measurements was checked. Study shows that it is possible to use laser technology to optimize location and height of devices which delay surface water runoff what allows to restore degraded hydrogenic habitats. Presented method supports small local retention what increases limited water resources in this region, decreases rapid runoff of surface water which causes frequent floods. Proposed method of modelling the location and height of the dams or locks is universal. Even though results are unique for each object the method is possible to be applied to every other situation.

Recent Advances in Light Detection and Ranging: Optical Modulation Solutions and Novel Nanotechnologies

AbstractLight detection and ranging (LiDAR) sensor is widely recognized as a critical component for accurate perception. However, there are a host of challenges that impede their performance, including low spatial resolution, high costs, large size, low reliability, and susceptibility to interference. It is challenging to overcome these issues using a single LiDAR module, necessitating the need for a review of current LiDAR technologies. The paper commences by introducing the fundamental principles of various laser rangefinders and discussing the optical modulation technologies used to prevent interference and ghost images. Next, the paper delves into the latest developments in laser technology, with a focus on enhancing the switching rate, compliance with eye safety regulations, miniaturization, and improving stability. One highly promising innovation is the photonic crystal surface emitting laser (PCSEL), a novel light source that boasts high‐speed, small divergence angles, and high‐power output. Finally, the paper discusses the advancements made in non‐solid‐state scanning and solid‐state scanning, such as improving stability, increasing scanning angles, and optimizing the manufacturing of mechanical and micro‐electromechanical systems (MEMS). Additionally, the paper highlights the recent advancements in nanotechnology, specifically metasurface technology, which offers superior capabilities such as beam deflection, enhanced field‐of‐view (FOV), and dynamic modulation.

3D/4D strategic lymph node diagnostics : The 4D representation of the human lymph node enables the observation and interpretation of the immune system in space and time

Lymph-node diagnostics is performed using thin sections, with help of immunohistochemistry by light microscopy and supplemented by molecular pathology. Which are the scientific and diagnostic perspectives of 3D and 4D lymph node investigations, using laser, scanning, and computer technologies? What is the impact of machine learning in complex data analysis. It was shown in different investigations that the analysis in space and time (3D/4D) of lymph node tissue is able to provide a lot of new information concerning biology and diagnostics and enable excellent evaluations applying machine learning. 3D and 4D analysis of human lymphoid tissue gives new insights into immunologic mechanisms and malignant lymphomas.

Use of both the diode and Er: YAG lasers in esthetic crown lengthening with the aid of digitally guided dual technique: 3 years follow-up.

To explore the feasibility of the usage of digital guides in combination with low- and high-power lasers for the treatment of excessive gingival display, also known as "gummy smile". Excessive gingival display due to altered passive eruption can affect patient's perception of their own esthetics and consequently have an impact on self-confidence. Therefore, the management of this condition should offer a predictable and stable long-lasting solution. To attain these objectives, digital planning emerges as a tool in optimizing the outcomes of crown lengthening surgery for this condition by enhancing precision through the use of surgical guides. Additionally, the usage of high- and low-powered lasers can provide a safe approach because of their tissue selective removal properties. The technique described showed satisfactory clinical results in the short- and long-term follow-up, leading to an improvement in patients' self-esteem. This approach integrates digital and laser technologies to deliver a surgical treatment characterized by precision, efficiency, and safety. Digital dentistry has contributed to innovative dental procedures, as personalizing surgical guides for patients, assisting and guiding incisions of the gingival margins, as well as the extension of the osteotomy, during the procedures for increasing the clinical crown. Furthermore, smile esthetics are directly related to an individual's improved emotional and social quality of life.

Advances in Ultrafast Fiber Lasers for Multiphoton Microscopy in Neuroscience

Multiphoton microscopy (MPM) has emerged as a vital tool in neuroscience, enabling deeper imaging with a broader field of view, as well as faster and sub-cellular resolution. Recent innovations in ultrafast fiber laser technology have revolutionized MPM applications in living brains, offering advantages like cost-effectiveness and user-friendliness. In this review, we explore the progress in ultrafast fiber laser technology, focusing on its integration into MPM for neuroscience research. We also examine the utility of femtosecond fiber lasers in fluorescence and label-free two- and three-photon microscopy applications within the field. Furthermore, we delve into future possibilities, including next-generation fiber laser designs, novel laser characteristics, and their potential for achieving high spatial and temporal resolution imaging. We also discuss the integration of fiber lasers with implanted microscopes, opening doors for clinical and fundamental neuroscience investigations.

Q-switched EDFL with copper phthalocyanines saturable absorber

We have successfully demonstrated Q-switching within the confines of an erbium-doped fiber laser (EDFL) cavity. This innovative approach leveraged copper phthalocyanines (CuPc) as a saturable absorber (SA), with the SA film made via the embedding method utilizing polyvinyl alcohol (PVA). The Q-switched EDFL achieved a minimum pulse width of 3.95 µs, a maximum pulse rate of 77.2 kHz and a maximum pulse energy of 49.2 nJ as it operated under a maximum pump power of 102.8 mW. Notably, this pioneering work marks the first instance of employing a CuPc PVA-based SA to produce a Q-switched laser within the 1.55 µm region. Our findings offer exciting prospects for advancements in Q-switched fiber laser technology.

In‐Source High‐Resolution Spectroscopy Using an Integrated Tunable Raman Laser

AbstractTunable single‐frequency lasers are the most prominent tool for high‐resolution spectroscopy, allowing for the study and exploitation of the electronic structure of atoms. A significant milestone relies on the demonstration of integrated laser technology for performing such a task. The device presented here is composed of a compact Fabry–Perot monolithic resonator capable of producing tunable and Fourier‐limited nanosecond pulses with a MHz‐class frequency stability without active cavity stabilization elements. It also has the remarkable capability of exploiting the Raman effect to funnel efficiently the broad spectrum of an input laser to a spectrally‐bright Stokes pulse at hard‐to‐access wavelength ranges. The targeted atom for the demonstrations is 152Sm, released as an atomic vapor in a hot cavity environment. Here, the Stokes field is tuned to a wavelength of 433.9 nm, while a crossed‐beams spectroscopy setup is used to minimize the Doppler broadened spectral features of the atoms. With this work, the suitability of integrated diamond Raman lasers as a high‐resolution in‐source spectroscopy tool is demonstrated, enabling many applications in atomic and nuclear physics. The integrated form‐factor and inherent simplicity makes such a laser an interesting prospect for quantum‐technology based sensing systems and related applications.

Towards a Practical Use of Sulfide Solid Electrolytes in Solid‐State Batteries: Impact of Dry Room Exposure on H2S Release and Material Properties

AbstractSulfide‐based solid electrolytes (SEs) are amongst the most promising solid electrolytes for the development of solid‐state batteries (SSBs) due to their high ionic conductivity and processing advantage over oxide‐based SEs. However, one of the main drawbacks of sulfide SEs is their rapid degradation in presence of humidity. In this study, we investigated the effect of exposing three different sulfide SEs (Li7P3S11, the argyrodite Li6PS5Cl and the chloride‐doped argyrodite Li6‐xPS5‐xCl1+x) to the atmosphere of a dry room at a dew point (DP)=−40 °C. For the first time to the best of our knowledge, enhanced infra‐red (IR) laser technology was employed to follow and quantify online and in‐situ H2S evolution by the SEs in a dry room environment over 16 h. It was found that argyrodite compounds evolved approximately 8 times less H2S compared to Li7P3S11 over 16 h of exposure with peak concentrations between 5 and 16 ppm vol. The exposed materials were studied using X‐ray diffraction, Raman spectroscopy, electrochemical impedance spectroscopy, X‐ray photoelectron spectrometry (XPS) and galvanostatic cycling. XPS results revealed a formation of Li2CO3 on the surface of argyrodite SEs, which served as a robust passivation layer limiting considerably reactions with the dry room atmosphere.

Backward scattering of laser plasma interactions from hundreds-of-joules broadband laser on thick target

The use of broadband laser technology is a novel approach for inhibiting processes related to laser plasma interactions (LPIs). In this study, several preliminary experiments into broadband-laser-driven LPIs are carried out using a newly established hundreds-of-joules broadband second-harmonic-generation laser facility. Through direct comparison with LPI results for a traditional narrowband laser, the actual LPI-suppression effect of the broadband laser is shown. The broadband laser had a clear suppressive effect on both back-stimulated Raman scattering and back-stimulated Brillouin scattering at laser intensities below 1 × 1015 W cm−2. An abnormal hot-electron phenomenon is also investigated, using targets of different thicknesses.