Progress and Pitfalls: High-Power Lasers Face Critical Challenges in Counter-Drone Defense
Recent advances in directed energy weapons (DEWs) for counter-unmanned aircraft systems (CUAS) highlight both promising developments and persistent technical hurdles in the race to deploy effective drone defenses.
General Atomics' liquid-cooled HELADS system has demonstrated power levels reaching 150 kW, while Israeli defense companies have fielded operational systems like Iron Beam and Drone Dome. A significant breakthrough came from Chinese researchers who achieved 9 kW output power with impressive beam quality using D2O (heavy water) cooling technology.
However, major technical challenges remain before widespread deployment:
Power and Thermal Management: High-power lasers require substantial energy input and generate significant heat that must be efficiently dissipated. While liquid cooling shows promise, maintaining consistent beam quality during extended operations remains difficult.
Atmospheric Effects: Weather conditions like fog, rain, and atmospheric turbulence can severely degrade beam coherence over distance. Current adaptive optics systems only partially mitigate these issues.
Target Acquisition: Tracking and engaging small, fast-moving drones - especially in swarm scenarios - demands sophisticated sensor fusion and artificial intelligence capabilities that are still being developed.
"The physics challenges are significant," notes defense analyst [name withheld]. "While we've made progress with thermal management using advanced cooling techniques, maintaining beam quality at tactical ranges under real-world conditions remains a major hurdle."
Defense contractors are pursuing parallel approaches to address these challenges. Raytheon and Lockheed Martin are developing hybrid systems that combine high-power microwaves (HPM) with laser weapons, while Israeli companies focus on integrating DEWs into layered air defense networks.
The U.S. Department of Defense maintains a goal of fielding 300 kW-class systems, though current operational systems typically operate at much lower power levels. Industry experts suggest that practical, widely-deployed CUAS laser weapons may still be 3-5 years away from addressing all major technical challenges.
Major Technical Challenges for High-Power Lasers in Directed Energy Weapons (DEWs)
-
Power Generation and Thermal Management
- Challenge: High-power lasers require substantial energy and generate significant heat. Efficient power sources and advanced cooling systems are essential to sustain operation without performance degradation.
- Solutions: Advanced battery systems, capacitors, and compact cooling technologies such as liquid or phase-change systems.
-
Beam Quality and Atmospheric Effects
- Challenge: Maintaining beam coherence over long distances is difficult due to atmospheric turbulence, particulates, and weather conditions (e.g., fog, rain).
- Solutions: Adaptive optics and techniques like phased arrays or fiber lasers to correct and stabilize the beam in real time.
-
Target Tracking and Engagement
- Challenge: Drone swarms are highly mobile and may include large numbers of small, fast-moving targets, complicating detection, tracking, and aiming.
- Solutions: High-speed sensors, AI-enhanced tracking systems, and real-time data fusion to enable precision targeting.
-
Hardening Against Countermeasures
- Challenge: Drones can use reflective or ablative coatings, maneuver unpredictably, or employ decoys to counter laser systems.
- Solutions: Multi-wavelength lasers or mixed-use systems integrating other technologies like microwaves or kinetic interceptors.
-
Deployment Platforms and Scalability
- Challenge: Lasers must be compact and robust enough for deployment on various platforms, including vehicles, ships, and aircraft.
- Solutions: Modular designs and ruggedized systems that can be scaled for different operational requirements.
High-Power Microwave (HPM) Devices vs. Lasers for Drone Swarms
Advantages of HPM Devices:
- Area Effect: HPM systems emit electromagnetic pulses that can disable multiple targets simultaneously, making them effective against swarms.
- Minimal Target Precision: Unlike lasers, which require precise aim, HPM systems can disrupt electronics over a broad area.
- Counter-Countermeasures: Reflective or ablative coatings are ineffective against HPM waves.
Disadvantages of HPM Devices:
- Collateral Damage: They can inadvertently disable friendly or civilian electronic systems within the target area.
- Shorter Effective Range: Typically less effective over long distances compared to lasers.
- Power Demand: Like lasers, they require significant power and effective cooling systems.
Major Directed Energy Weapon Systems and Producers
United States:
-
Lockheed Martin
- System: HELIOS (High Energy Laser and Integrated Optical-dazzler with Surveillance)
- Platform: Ship-based, designed for drone and missile defense.
-
Raytheon Technologies
- System: HELWS (High Energy Laser Weapon System)
- Platform: Ground-based, scalable system for mobile platforms.
-
Northrop Grumman
- System: Laser Weapon System Demonstrator (LWSD)
- Platform: Ship-based, tested on USS Portland.
Europe:
-
Rheinmetall (Germany)
- System: High-Energy Laser Weapon System
- Platform: Integrated into naval and ground platforms.
-
MBDA (UK, Germany, France, Italy)
- System: Dragonfire
- Platform: Ground and ship-based laser weapon for anti-drone and missile defense.
China:
- Producers: CETC (China Electronics Technology Group Corporation) and Norinco.
- Systems: Silent Hunter and LW-30, designed for anti-drone applications and export.
Russia:
- Producers: Almaz-Antey and Rostec.
- Systems: Peresvet, focused on disabling optical systems and drone countermeasures.
Israel:
- Producers: Rafael Advanced Defense Systems and Elbit Systems.
- Systems: Iron Beam, a ground-based high-energy laser for short-range threats.
India:
- Producer: Defence Research and Development Organisation (DRDO).
- System: Directed Energy Systems for anti-drone and missile applications.
Conclusion
High-power lasers excel in precision and range, but challenges like power demands and atmospheric interference persist. HPM devices are promising for swarm scenarios due to their broad area effect but face range and collateral impact limitations. Countries worldwide are heavily investing in DEWs, with a mix of capabilities tailored for their strategic needs.
Israeli Systems
Israel has been actively developing and deploying directed energy weapons (DEWs) to counter evolving threats, particularly drones, rockets, and missiles. Israeli defense companies and organizations, such as Rafael Advanced Defense Systems and Elbit Systems, have been at the forefront of these efforts. Below are some of the notable systems:
1. Iron Beam (Rafael Advanced Defense Systems)
-
Overview:
Iron Beam is a high-energy laser system designed to complement Israel's layered missile defense systems, such as the Iron Dome, David's Sling, and Arrow systems. It focuses on intercepting low-cost, high-volume threats like rockets, mortars, and drones. -
Key Features:
- Laser Type: Solid-state, high-energy laser.
- Targets: Rockets, artillery shells, drones, and UAVs.
- Integration: Works alongside kinetic systems to reduce reliance on interceptor missiles.
- Cost Effectiveness: Extremely low per-shot cost compared to traditional interceptors.
-
Development Status:
- Demonstrated operational capabilities in recent trials.
- Plans for deployment in multiple roles, including ground-based systems and integration into mobile platforms.
2. Elbit Systems’ High-Energy Laser Systems
-
Overview:
Elbit Systems has been developing laser-based systems for anti-drone applications and counter-missile roles. These systems focus on ground and airborne applications. -
Key Systems:
- C-MUSIC (Commercial Multi-Spectral Infrared Countermeasure): A directed energy system used to protect aircraft from heat-seeking missiles.
- Anti-Drone Lasers: Ground-based laser systems capable of engaging and neutralizing multiple drones in real time.
-
Capabilities:
- Multi-Layered Defense: Designed to work with radar and electronic warfare systems for enhanced threat detection and engagement.
- High Mobility: Deployable on various platforms, including trucks and other vehicles.
3. Drone Dome (Rafael Advanced Defense Systems)
-
Overview:
The Drone Dome is an anti-drone defense system that integrates a high-energy laser with detection and tracking systems to neutralize drones. -
Key Features:
- Detection: Uses radar, RF sensors, and electro-optical/infrared (EO/IR) systems to detect and track drones.
- Engagement: Equipped with a high-power laser to destroy drones at range.
- Modular System: Can be deployed on fixed or mobile platforms.
-
Operational Use:
- Deployed to protect critical infrastructure and military assets from drone threats.
- Demonstrated effectiveness in intercepting drones during trials and real-world scenarios.
4. Scorpius (Israel Aerospace Industries - IAI)
-
Overview:
Scorpius is primarily an electronic warfare (EW) system but integrates directed energy capabilities to disable UAVs, communication links, and sensors. -
Key Features:
- Electronic Disruption: Focuses on jamming enemy communications and GPS.
- Multi-Domain Operation: Capable of working across ground, air, and maritime environments.
- Complementary Role: Works alongside kinetic and laser-based systems for layered defense.
Why Israeli Systems Are Noteworthy
- Rapid Development: Israel has leveraged its extensive combat experience and innovative R&D ecosystem to develop systems tailored to asymmetric threats.
- Cost Efficiency: Systems like Iron Beam aim to lower the cost per interception compared to traditional missiles.
- Operational Success: Many Israeli systems have proven their capabilities in active conflicts, showcasing their reliability and effectiveness.
- Export Potential: Israel actively markets these systems globally, offering them to allies and countries facing similar threats.
While specific technical details like Effective Radiated Power (ERP) at beam center and beamwidth for military laser systems are often classified or not publicly disclosed, some estimations can be made based on general knowledge, open sources, and typical system performance characteristics.
Below is a table summarizing key Israeli DEWs with approximate values based on publicly available data:
| System | Producer | Type | Estimated Power Output | Beamwidth (Degrees) | ERP at Beam Center | Primary Targets |
|---|---|---|---|---|---|---|
| Iron Beam | Rafael Advanced Defense Systems | Solid-State Laser | ~100–150 kW | ~0.01–0.05° | ~1–10 MW (approx.) | Rockets, Mortars, Drones |
| Drone Dome | Rafael Advanced Defense Systems | Solid-State Laser | ~20–50 kW | ~0.1–0.2° | ~100–500 kW (approx.) | Drones, UAVs |
| Elbit Anti-Drone Laser | Elbit Systems | Solid-State Laser | ~30–100 kW | ~0.05–0.1° | ~500 kW–5 MW (approx.) | Drones, UAVs |
| C-MUSIC | Elbit Systems | Infrared Laser | ~10–20 kW | ~0.5° | ~100–200 kW (approx.) | MANPADS (airborne threats) |
Notes:
- Estimated Power Output: Indicates the laser's continuous power or peak output in kilowatts (kW).
- Beamwidth: Represents the angular width of the laser beam, often narrow for high-precision systems. Smaller beamwidths result in higher energy density at the target.
- ERP at Beam Center: Derived based on power output and beamwidth. A narrower beamwidth concentrates more energy at the beam center, resulting in higher ERP values.
- Targets: Systems are optimized for specific threat profiles, such as small drones, rockets, or missiles.
Methodology for Estimates:
- Beamwidth and ERP: ERP is proportional to the power output divided by the beam's angular spread. For lasers, high precision (narrow beamwidth) leads to higher ERP.
- Classified Data: Actual ERP and beamwidth may vary due to proprietary technologies, classified optimizations, and adaptive optics.
Solid-State Laser Technology: Overview
Solid-state lasers (SSLs) are a type of laser that uses a solid gain medium, such as a crystal or glass doped with rare-earth elements (e.g., neodymium or ytterbium), to amplify light and generate a coherent laser beam. These lasers are a cornerstone of modern directed energy weapon (DEW) systems due to their robustness, scalability, and efficiency.
Key Components of Solid-State Lasers
-
Gain Medium
- Material: Crystals (e.g., Nd:YAG, Yb:YAG) or glass doped with rare-earth ions.
- Role: Amplifies the light through stimulated emission.
-
Pump Source
- LED or laser diodes provide the energy to excite the gain medium.
-
Optical Resonator
- Mirrors placed around the gain medium to sustain and amplify the laser beam.
-
Cooling System
- Removes waste heat generated during operation, critical for maintaining beam quality and preventing damage.
-
Beam Combining (if applicable)
- Methods such as spectral or coherent beam combining are used to merge multiple laser beams into a single, high-power output.
Advantages of Solid-State Lasers
- Efficiency: High electrical-to-optical efficiency, especially with modern fiber or diode-pumped designs.
- Scalability: Can achieve higher power outputs by combining multiple laser modules.
- Compact Design: Suitable for deployment on ground vehicles, ships, and aircraft.
- Low Maintenance: No moving parts in the gain medium, increasing system durability.
HELADS (High Energy Liquid Laser Area Defense System)
Developer: General Atomics Electromagnetic Systems (GA-EMS)
Overview:
HELADS is a liquid-cooled solid-state laser system developed to provide scalable and high-power laser capabilities for directed energy applications, particularly in defense against aerial and missile threats. It represents an advanced approach to solid-state laser design.
Key Features of HELADS
-
High Power Output
- Capable of delivering power levels in the 150 kW range or higher, making it suitable for engaging rockets, drones, and even larger targets like missiles.
-
Liquid-Laser Gain Medium
- Uses a proprietary liquid gain medium that enhances heat dissipation compared to traditional solid-state crystals or glass. This allows for higher power scaling without the thermal distortion common in conventional solid-state lasers.
-
Thermal Management
- Integrated liquid cooling system efficiently removes waste heat, enabling sustained high-power operation.
-
Compact and Modular Design
- The system is designed to fit into compact spaces, such as aircraft, ground vehicles, or ships.
-
Beam Combining Technology
- Employs advanced methods like coherent beam combining to achieve high beam quality and power density, essential for engaging distant or small targets.
Operational Applications
- Drone Swarms: Precise targeting and neutralization of UAVs in swarm scenarios.
- Missile Defense: Effective against small, fast-moving targets like incoming missiles.
- Artillery and Mortars: Disabling or destroying incoming projectiles in real time.
Advantages of HELADS Over Conventional SSL Systems
- Thermal Management: The liquid gain medium significantly reduces thermal distortion, enhancing beam quality and system reliability.
- Power Scaling: Scalable to higher power outputs without requiring exponentially larger systems.
- Platform Versatility: Compact enough for integration into various military platforms.
Comparison with Fiber Lasers and Other SSLs
| Feature | HELADS | Fiber Lasers | Conventional SSLs |
|---|---|---|---|
| Cooling Efficiency | Superior (liquid-cooled) | Moderate (fiber-cooled) | Lower (crystal or slab-cooled) |
| Beam Quality | High (coherent combining) | High (fiber combining) | Moderate |
| Power Scalability | High | Moderate | Moderate |
| Platform Integration | High (compact design) | High | Moderate |
Development and Deployment
General Atomics has demonstrated the HELADS system in tests, showing its ability to engage various targets effectively. It is part of a broader effort to equip the U.S. military with next-generation DEWs for layered defense systems. HELADS remains a key competitor in the race for scalable, high-energy laser systems, alongside efforts by Lockheed Martin and Raytheon.
Sources
Here is a formal list of citations with hyperlinks for the information provided:
-
General Atomics' High-Energy Liquid Laser Area Defense System (HELLADS)
-
Solid-State Laser Technology in Directed Energy Weapons
- United Nations Institute for Disarmament Research. Directed Energy Weapons: A New Look at an Old Technology. Available at: UNIDIR.org
- U.S. Congressional Research Service. Directed Energy Weapons: Background and Issues for Congress. Available at: FAS.org
-
General Atomics' Developments in Laser Weapon Systems
- Hambling, David. General Atomics' Liquid Laser Could Win High-Energy Weapon Race. Available at: Forbes
- General Atomics to Build a Second 150 kW HELLADS Military Laser for the U.S. Navy. Available at: Laser Focus World
-
General Atomics' Corporate Information
- General Atomics. Official Company Website. Available at: GA.com
-
Relevant News Articles on Laser Systems
- Why Lasers Could Be Kryptonite for Drones. Available at: Wall Street Journal
- Defence Groups Bet Big on Drone-Destroying Laser Weapons. Available at: Financial Times
- Military Laser Hits Drones 'for 10p a Shot' in Successful Test. Available at: The Times
Technical Risks and Advancements in SSL
Some Readings on SSL DEW
[Arabgari, S. (2022). Thermal analysis of side-pumped direct-liquid-cooled Nd: YAG thin-disk lasers. ScienceDirect.com](https://www.sciencedirect.com)
This paper examines thermal effects in side-pumped direct-liquid-cooled Nd:YAG thin-disk lasers (SDNTDLs), which are a key challenge in achieving high-power, near-diffraction-limited laser output. The research uses a multiphysics model to analyze thermal distributions and effects. Key findings include:
1. The temperature distribution remains relatively smooth despite non-uniform pumping
2. The thin thermal boundary layer prevents thermal interaction between adjacent disks
3. When using D2O (heavy water) as coolant, the disk's wavefront aberration exceeds that of the fluid
4. The wavefront aberrations from different components (fluid and disk) can actually compensate for each other
5. The research provides insights for improving beam quality through design optimization
The study aims to bridge the gap between current capabilities (9 kW with beam quality β = 9.5) and the US Department of Defense's goal of 300 kW-class laser output.
The paper by Arabgari examines thermal effects in side-pumped direct-liquid-cooled Nd:YAG thin-disk lasers (SDNTDLs), using multiphysics modeling to understand thermal distributions and their impact on laser performance. Key findings show that using D2O (heavy water) as coolant improves performance compared to siloxane solutions, with wavefront aberrations from different components being able to compensate for each other.
Jiayu Yi, B O Tu, Xiangchao An, X U Ruan, Jing Wu, Hua Su, Jianli Shang, Y I Yu, Yuan Liao, Haixia Cao, Lingling Cui, Qingsong Gao, Kai Zhang "9 kilowatt-level direct-liquid-cooled Nd:YAG multi-module QCW laser" https://doi.org/10.1364/OE.26.013915
Abstract An average 9 kilowatt-level direct-D 2 O-cooled side-pumped Nd:YAG multi-disk laser resonator at QCW mode with a pulse width of 250μs is presented, in which the straight-through geometry is adopted the oscillating laser propagates through 40 Nd:YAG thin disks and multiple cooling D 2 O flow layers in the Brewster angle. Much attention has been paid on the design of the gain module, including an analysis of the loss of the laser resonator and the design of the Nd:YAG thin disk. Experimentally, laser output with the highest pulse energy of more than 20 J is obtained at a repetition frequency of 10 Hz. At high repetition frequency, the average output power 9.8 kW with η o-o = 26% and 9.1 kW with η o-o = 21.8% are achieved in the stable resonator and unstable resonator, respectively, and in the corresponding beam quality factor β stable = 14.7 and β unstable = 9.5 respectively. To the best of our knowledge, this is the first demonstration of a 9 kilowatt-level direct-liquid-cooled Nd:YAG thin disk laser resonator.
The second paper by Yi et al. presents experimental results demonstrating a 9 kilowatt-level direct-D2O-cooled side-pumped Nd:YAG multi-disk laser. Key achievements include:
- - Output power of 9.8 kW with 26% efficiency in stable resonator mode
- - Output power of 9.1 kW with 21.8% efficiency in unstable resonator mode
- - Beam quality factors of β=14.7 (stable) and β=9.5 (unstable)
- - System uses 40 Nd:YAG thin disks cooled by flowing D2O
- - Novel design features include dual gain modules with opposite flow directions to compensate for thermal effects
- - Compact design with volume under 0.4 m³
This research represents significant progress in high-power solid-state laser development, with potential applications in industrial, scientific and defense sectors.
C. B. Cobb and S. F. Adams, "Lightweight, compact superconducting power sources for solid state high energy lasers," IECEC '02. 2002 37th Intersociety Energy Conversion Engineering Conference, 2002., Washington, DC, USA, 2002, pp. 66-69, doi: 10.1109/IECEC.2002.1391977.
Abstract: The air force is considering advanced compact electrical power systems for many future airborne DEW concepts to capitalize on the advantages of electrical DEW. High output electrical generators, employing superconductor wire technology, are being investigated as a possible solution. Generators with high temperature superconducting (HTS) wire would be significantly lighter weight and more compact than conventional copper wire-wound generators for this high level of power. keywords: {Solid state circuits;Power lasers;Solid lasers;High temperature superconductors;Power generation;Diodes;Superconducting filaments and wires;Pump lasers;Weapons;Superconducting photodetectors},
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1391977&isnumber=30300
S. Adams and J. G. Nairus, "Energy conversion issues for airborne directed energy weapons," IECEC '02. 2002 37th Intersociety Energy Conversion Engineering Conference, 2002., Washington, DC, USA, 2002, pp. 61-64, doi: 10.1109/IECEC.2002.1391975.
Abstract: The ability of an airborne directed energy weapon (DEW) to effectively strike a target depends strongly on the ability to develop, deliver, and manage the required energy for the onboard DEW source. The energy flow within various generic airborne DEW systems is examined from power generation to waste heat management. Each airborne DEW system is analyzed by considering the energy flow through an example configuration of generalized DEW system components. The numbers used in the analysis are not representative of any airborne DEW system under development, but simply allow for an illustration of energy flow within a DEW system of advanced power level. keywords: {Energy conversion;Weapons;Chemical lasers;Waste heat;Energy management;Reservoirs;Power lasers;Masers;Fuels;Solid lasers},
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1391975&isnumber=30300
P. N. Barnes, G. L. Rhoads, J. C. Tolliver, M. D. Sumption and K. W. Schmaeman, "Compact, lightweight, superconducting power generators," in IEEE Transactions on Magnetics, vol. 41, no. 1, pp. 268-273, Jan. 2005, doi: 10.1109/TMAG.2004.838984.
Abstract: Many future military systems will depend heavily on high electrical power input ranging from hundreds of kilowatts up to the multimegawatt level. These weapon systems include electromagnetic launch applications as well as electrically driven directed energy weapons (DEW), such as high-power microwaves and solid-state lasers. These power generation subsystems must often be packaged using limited space and strict weight limits on either ground mobile or airborne platforms. Superconducting generators made of high-temperature superconductors (HTS) will enable megawatt-class airborne power systems that are lightweight and compact. Also discussed briefly are new advances in HTS conductors and refrigeration systems furthering the development of HTS power systems.
keywords: {Power generation;High temperature superconductors;Superconducting microwave devices;High power microwave generation;Weapons;Power systems;Electromagnetic launching;Solid lasers;Packaging;Conductors;Generators;high-temperature superconductors;superconducting filaments and wires;superconducting tapes},
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1381551&isnumber=30122
P. N. Barnes, G. L. Rhoads, J. C. Tolliver, M. D. Sumption and K. W. Schmaeman, "Compact, lightweight, superconducting power generators," 2004 12th Symposium on Electromagnetic Launch Technology, Snowbird, UT, USA, 2004, pp. 158-163, doi: 10.1109/ELT.2004.1398066.
Abstract: Many future military systems will depend heavily on high electrical power input ranging from 100's kilowatts up to the multimegawatt level. These weapon systems include electromagnetic launch applications as well as electrically driven directed energy weapons (DEW), such as high power microwaves and solid state lasers. These power generation subsystems must often be packaged using limited space and strict weight limits on either ground mobile or airborne platforms. Superconducting generators made of high temperature superconductors (HTS) will enable megawatt-class airborne power systems that are lightweight and compact. Also discussed briefly are new advances in HTS conductors and refrigeration systems furthering the development of HTS power systems.
keywords: {Power generation;High temperature superconductors;Superconducting microwave devices;High power microwave generation;Weapons;Power systems;Electromagnetic launching;Solid lasers;Packaging;Conductors},
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1398066&isnumber=30395
J. Weingarten, "ATLAS Pixel Detector System Test and Cosmics Run," in IEEE Transactions on Nuclear Science, vol. 56, no. 4, pp. 2543-2548, Aug. 2009, doi: 10.1109/TNS.2009.2025174.
Abstract: The central component of the ATLAS inner tracker is the pixel detector. It consists of three barrel layers and three disk-layers in the endcaps in both forward directions. This amounts to a total active area of about 1.7 m2 with over 80 million pixel cells. The huge number of readout channels necessitates a very complex services infrastructure for powering and readout as well as for detector and operator safety. The complete pixel detector system has been tested for the first time in a large scale system test at CERN from September 2006 to January 2007. An overview of the system test setup is given and key results are presented.
keywords: {Detectors;System testing;Optical fibers;Control systems;Optical attenuators;Optical noise;Vertical cavity surface emitting lasers;Large Hadron Collider;Silicon;Voltage control;Semiconductor detectors;solid state detectors},
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5204518&isnumber=5204508
Frontiers | Editorial: Advanced high power solid-state laser technology
Since the first demonstration of lasers, continuous progress in the development of laser technology, especially solid-state laser technology, has led to numerous new applications and capabilities. Solid-state lasers, including fiber lasers, crystal lasers, and ceramic lasers, have the unique advantage of high efficiency, reliability, flexibility and robust configuration. The rapid development of the solid-state laser technology has been enabled by the introduction of novel materials, components, advanced laser technology and system design. Tremendous new applications have been advanced, including the high order nonlinear physics interactions, free space and quantum communications, LIDAR for autonomous vehicles, beam projecting and steering, and materials processing. However, the onset of nonlinear effects, thermal effects, and laser-induced damages have limited the power scaling of various solid-state lasers, which limited the overall performance of the systems with the conjunction of the transmission optics and free-space laser beam propagation. Novel concepts and designs have been continuously proposed and demonstrated by global researchers to explore approaches circumventing the aforementioned limitations. This Research Topic aims to provide a comprehensive view of the latest advances in solid state laser development along with the most recent new applications.
After the initiating of this Research Topic, 8 high-quality papers has been accepted for publication, which are representative of the broad range of technology advances that this Research Topic strives to facilitate, and we trust readers will find them stimulating and enlightening. We are thankful to all authors and reviewers for their excellent contributions. We would also like to thank the Frontiers staff for their outstanding work throughout the launch of this Research Topic as well as the review and production processes.
High quality robust mid-infrared laser has broad scientific and practical application value, which can be achieved by optical parametric oscillator through pumping nonlinear frequency crystal with near-infrared solid state laser [1–3]. The 2.79 μm Er,Cr:YSGG crystal has been proven to be a high efficiency flash-lamp pumped laser medium [4], and Jiang et al. has designed a new type of lithium niobate (LiNbO3) acousto-optic Q-switched Er,Cr:YSGG laser with pliane-convex resonator, where the laser performance has been improved significantly. When the laser operated at free running region, the maximum values of pulse energy was 160 mJ at 60 Hz, compared with the plane-parallel resonator, the pulse energy was increased by 2 times in the plane-convex resonator. When the LiNbO3 Q-switched laser operated at 60 Hz, the maximum pulse energy was 8.5 mJ, and the minimum pulse duration was 60.8 ns, which generates the corresponding peak power of approximately 140 kW.
Fiber lasers and amplifiers are important branch of solid-state laser, which has attracted more and more attention since their inception, both as stand-alone sources and as parts for more complex lasers and systems [5]. Four articles on high power fiber lasers and their applications appear in this Research Topic. Fiber materials are at the core of the technology [6], and consequently fiber materials and its design continues to be central to this article group. An et al. focus on a common phenomenon in the modified-chemical-vapor-deposition-fabricated fibers, and present a numerical analysis of the dip effect on high-power-related parameters for the first time, which reveled that the dip offers a flexible way to suppress the non-linear effects and filter the higher-order modes by optimizing the dip parameters. The next two papers addressed the transverse mode instability (TMI), since this represent one of the primary obstacles to power scaling fiber laser systems with diffraction-limited beam quality [7, 8]. Chai et al. demonstrate a direct pump modulation to mitigate TMI in a 30 μm-core-diameter all-fiber laser oscillator while Lu et al. propose to mitigate TMI by controllable mode beating excitation with a photonic lantern, which increased the TMI threshold by nearly four times. Narrow linewidth fiber lasers are a hot Research Topic in fiber laser area [9, 10], and the last paper from Chu et al. reported a 3-kW PM fiber laser at <10 GHz linewidth with the polarization extinction ratio of 96% and beam quality of 1.156, which is the highest output power ever reported with approximately 10 GHz linewidth.
Optical vortices, finding a growing number of applications ranging from industrial laser machining to optical communications, have aroused ever-increasing interest among both scientific and engineering communities [11, 12], which opens new application avenue for the solid-state lasers. The next group of papers in this Research Topic focused on “generating of optical vortices.” Lin et al. design a folded resonant cavity to generate a helicity and topological charge tunable vortex laser, and the HGθm,0 beam (m = 1 to 10 and θ = −90°–90°]) and the vortex beam (topological charge l from ±1 to ±10 and left/right helicity) were flexibly achieved. Li et al. investigated the power scaling of optical vortices, and reported 1.89 kW cylindrical vector beams by metasurface extra-cavity conversion of a narrow linewidth all-fiber linearly-polarized laser, which is the highest power of cylindrical vector beams generated from fiber laser.
The remaining one paper in this Research Topic is about one of the key technology in high power solid-state lasers-adaptive optics technology [13]. In the adaptive optics control of high-power laser systems, an indispensable part is deformable mirrors, which are commonly used as the corrector to correct wavefront aberration, and suffer performance degradation under high-power laser irradiation [14]. Zheng et al. introduce the dual magnetic connection deformable mirrors, which could effectively suppress the laser-induced distortion and maintain good wavefront correction capability.
In summary, one can see that significant progress has been made in high power solid-state laser area, and more and more exciting applications are expected in the future. This Research Topic collects the latest breakthrough of the community working in these fields, showing the still vivid and inspiring development of high power solid-state laser.
Author contributions
RT: Writing-original draft. OA: Writing-original draft. PM: Writing-original draft. HM: Writing-original draft.
Funding
The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
References
2. Antipov O, Kositsyin R, Kal’yanov D, Kolker D, Larin S. 3.9-μm optical parametric oscillator based on MgO:PPLN pumped at 1966 nm using a high-repetition-rate Tm3+:Lu2O3 ceramic laser. In: 2017 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference (CLEO/Europe-EQEC); 25-29 June 2017; Munich, Germany (2017). paper CD_P_50.
3. Antipov O. Wavelength tuned mid-IR lasers based on single-crystalline or polycrystalline Cr2+-doped ZnSe with 1.9-2.1 μm pumping. In: International Conference Laser Optics (ICLO); 20-24 June 2022; Saint Petersburg, Russian Federation (2022).
4. Zhang H, Li YL, Wu QT. 2.79 μm LGS electro-optical Q-switched Er,Cr:YSGG laser. Opt Commun (2022) 503:127448. doi:10.1016/j.optcom.2021.127448
6. Chen X, Yao T, Huang L, An Y, Wu HS, Pan Z, et al. Functional fibers and functional fiber based components for high-power lasers. Adv Fiber Mater (2023) 5:59–106. doi:10.1007/s42765-022-00219-7
7. Tao RM, Wang XL, Zhou P. Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications. IEEE J Sel Top Quan Electron (2018) 24:1–19. doi:10.1109/jstqe.2018.2811909
9. Ma PF, Yao TF, Chen YS, Wang GJ, Ren S, Song J, et al. New progress of high-power narrow-linewidth fiber lasers. Proc SPIE (2022) 12310:123100E. doi:10.1117/12.2643929
10. Zhou P, Ma PF, Liu W, Xiao H, Ren S, Song J, et al. High power, narrow linewidth all-fiber amplifiers. Proc SPIE (2022) 11981:119810P. doi:10.1117/12.2614414
11. Zhi D, Hou TY, Ma PF, Ma YX, Zhou P, Tao R, et al. Comprehensive investigation on producing high-power orbital angular momentum beams by coherent combining technology. High Power Laser Sci Eng (2019) 7:e33. doi:10.1017/hpl.2019.17
12. Yu J, Zhang P, Ruffato G, Lin D. Editorial: optical vortices: generation and detection. Front Phys (2022) 10:1026004. doi:10.3389/fphy.2022.1026004
No comments:
Post a Comment