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[Takunori Taira](https://orcid.org/0000-0003-2512-7836), Jun Hayashi, [Nicolaie Pavel](https://orcid.org/0000-0002-0120-1184), [Tohru Suzuki](https://orcid.org/0000-0001-9458-6863)

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Tiny integrated lasers and their application to industrial laser technologies: feature issue introductionIntroduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31204Tiny integrated lasers and their application toindustrial laser technologies: feature issueintroductionTAKUNORI TAIRA,1,2,6 JUN HAYASHI,3 NICOLAIE PAVEL,4,7 ANDTOHRU SUZUKI51Laser-Driven Electron-Acceleration Technology Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cha,Sayo-gun, Hyogo 679-5148, Japan2Division of Research Innovation and Collaboration, Institute for Molecular Science, 38 Myodaiji, Okazaki,Aichi 444-8585, Japan3Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501,Japan4National Institute for Laser, Plasma and Radiation Physics, Laboratory of Solid-State QuantumElectronics, Atomistilor 409, Magurele 077125, Ilfov, Romania5National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan6taira@spring8.or.jp7nicolaie.pavel@inflpr.roAbstract: This issue of Optics Express features 18 papers, prepared primarily by authors whoparticipated in the 10th Tiny Integrated Laser and Laser Ignition Conference 2024 (TILA-LIC2024), held on 24–26 April 2024 in Pacifico Yokohama, Yokohama, Japan, as part of the Opticsand Photonics International Congress 2024; contributions from other authors related to the topicof tiny integrated lasers were welcomed. This review summarizes these articles, covering resultsin the fields of lasers and laser optics, nonlinear optics, optical fibers, optical materials, andspectroscopy. Innovations in photonics, also called giant micro-photonics, have allowed thecreation of ubiquitous lasers that can operate in diverse fields and conditions, thus opening thedoor to new applications and discoveries that advance humanity.© 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing AgreementThe Tiny Integrated Laser and Laser Ignition Conference (TILA-LIC) is an international meeting,organized by the Micro Solid-State Photonics Association, Japan within the Optics and PhotonicsInternational Congress, which is held annually, usually in April, at the Pacifico Yokohama Center,Yokohama, Japan. First organized in 2013, then called the Laser Ignition Conference (LIC 2013),the conference reached its 10th edition in 2024. The conference is a forum for discussing variousaspects related to ubiquitous laser sources and phenomena associated with high-intense laserpulses. Key topics areas covered by TILA-LIC include the advances in optical materials fortiny integrated laser (development and spectroscopic characterization of crystals, glasses andceramic laser materials; nonlinear crystals; bonding technologies and composite materials forlaser applications); development of tiny integrated lasers (modelling, design, realization andcharacterization; power-scalable laser architectures; solid-state micro-chip lasers; laser resonators,thermal management and beam quality control); discussion of various phenomena induced bypowerful miniature lasers (laser induced breakdown; laser ignition; laser acceleration); as well asindustrial applications of tiny integrated lasers (laser peening; ultrafast laser processing; laserignition for green generation, or THz generation and applications).A total of 45 communications were delivered at the TILA-LIC 2024 conference, consisting ofone plenary talk, one keynote speech, one tutorial, 11 invited talks and 31 contributed papers.The presentations were organized into 10 thematic sessions, primarily focused on laser materials,laser system development, and their applications. Additionally, a poster session was held to#571207 https://doi.org/10.1364/OE.571207Journal © 2025 Received 24 Jun 2025; published 15 Jul 2025https://orcid.org/0000-0003-2512-7836https://orcid.org/0000-0002-0120-1184https://orcid.org/0000-0001-9458-6863mailto:taira@spring8.or.jpmailto:nicolaie.pavel@inflpr.rohttps://doi.org/10.1364/OA_License_v2#VOR-OAhttps://crossmark.crossref.org/dialog/?doi=10.1364/OE.571207&domain=pdf&date_stamp=2025-07-15Introduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31205complement the oral presentations. Researchers from 10 different countries contributed to theconference (Fig. 1). A dedicated session, featuring enterprises from Japan, was held to discussthe transfer of laser technology to societal applications.Fig. 1. Participants at the 10th Tiny Integrated Laser and Laser Ignition Conference, 24 -26 April 2024, Pacifico Yokohama, Yokohama, Japan.A brief summary of the articles published in this feature issue of Optics Express is presentedbelow.Laser sources with emission in the 1.4 µm to 1.8 µm spectral range are eye-safe, becausethe radiation is absorbed by the vitreous body before reaching the retina. Also, lasers with awavelength of 1.5 µm are of interest in various applications, such as optical communications,remote sensing, or range finding. Chen et al. have developed a high-peak-power, narrow-pulse-width acousto-optic Q-switched Nd:YVO4/YVO4 eye-safe Raman laser at 1525 nm [1]. Theydesigned a compact laser cavity and showed that the cavity dumping effect leads to a considerablenarrowing of the pulse width. The use of a YVO4 Raman crystal with a dichroic coating led to areduction of the scattering and absorption losses for the Stokes wave, resulting in good-qualitylaser beams (M2 factor below 3.0). An average power exceeding 4.2 W was achieved at repetitionrates ranging from 50 kHz to 150 kHz with maximum peak powers of 53 kW and 25 kW,respectively. These values are reported to be nearly an order of magnitude higher than previouslypublished results for Nd:YVO4/YVO4 eye-safe Q-switched lasers.In human health, accurate measurement of carboxyhemoglobin (HbCO) in blood, which isinduced by CO exposure, is important for the safety of packed red blood cells transfusion. Inaddition, HbCO levels allow the assessment of CO-poisoning in forensic medicine. A compactdual-wavelength laser that emits at 555 nm and 579.5 nm and that can be used to measureHbCO levels in blood is reported by Chen et al. [2]. The design uses a Nd:YVO4/KGW/LBOstructure, in which intracavity stimulated Raman scattering of an Np-cut KGW crystal producesthe Stokes wave at 1159 nm from the fundamental wave at 1064 nm of the Nd:YVO4 crystal. Thesecond harmonic generation of the Stokes wave with a LiB3O5 (LBO) nonlinear crystal generateslaser radiation at 579.5 nm. A second LBO crystal is used to obtain laser radiation at 555 nm,through the sum frequency generation of the Stokes and fundamental waves. By controlling thetemperature of the second LBO crystal, equal powers of 5.5 W were achieved at both wavelengthsof 555 nm and 579.5 nm.Gallium compounds possess good thermal properties and spectroscopic characteristics, makingthem well-suited for the development of solid-state lasers emitting in the 2 µm range. Slimi et al.Introduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31206obtained a Ho:Y3Ga5O12 (Ho:YGG) laser crystal through the optical floating zone technique inan oxygen-rich atmosphere [3]. The investigation of the spectroscopic properties concluded that,compared to Ho:YAG, the Ho:YGG medium presents stronger homogeneous line broadeningin the absorption and stimulated-emission spectra around 2 µm, thus having a broader gainbandwidth; in addition, Ho:YGG has a smoother gain cross-section and a longer luminescencelifetime of the upper 5I7 laser manifold. Optical pumping of a 2.86-at.% Ho:YGG crystal bya Tm-fiber laser at 1908nm allowed continuous-wave operation with a power of 976 mW at2085nm and 2109 nm. The slope efficiency (with respect to the absorbed pump power) was50.1%. Further research will aim to improve the laser performances and explore the possibilityof achieving ultrashort pulse generation at ∼2 µm.Achieving thermal stability in 2-µm emitting single-doped Tm3+ lasers present a significantchallenge due to photon de-excitation caused by the ground-state reabsorption (GSRA) effect.To precisely quantify the thermal power within a gain medium, Li et al. developed a thermalconversion coefficient model by incorporating GSRA into the rate equations [4]. Theoreticalmodeling has demonstrated that GSRA leads to a reduction in the pump power range withinwhich the laser can operate. To validate the model’s applicability, extensive experiments wereconducted on a Tm:YAP laser pumped at 795 nm using a fiber-coupled semiconductor laser.This model is expected to contribute to the design of resonators that enhance laser performanceat 2 µm while improving thermal stability.Waveguide lasers allow for high (near unit) mode-matching between the laser and pumpbeams, resulting in laser emission at a low threshold and good slope of efficiency; this geometryallows for very compact laser resonators. Using direct writing with femtosecond (fs) laserbeams, a technique intensively applied in recent years, different waveguide geometries can berealized in a wide variety of laser active media. A paper by Kim et al. discusses the fabricationof a double-track waveguide in Yb:CaF2 using direct writing with a fs-laser beam [5]. Thesuccessful operation of this waveguide is demonstrated in both Q-switched mode-locked (QSML)and continuous-wave mode-locked (CWML) regimes. The pump is done with a tapered diodeamplifier, with an emission at 979.4 nm for good absorption in the waveguide. A semiconductorsaturable absorber output coupler was used for mode-locking. QSWL operating regime at 1047nm with 65 kHz repetition rate and pulse duration of 3 µs was obtained. Furthermore, in theCWML regime, the device yielded pulses at 1036 nm with 979 fs duration at 298 MHz repetitionrate. Maximum output power was 51 mW in both operation modes.Using the fs-laser direct writing method, Sun et al. have realized in Nd:YAG a semi-tapereddepressed-cladding waveguide of tubular shape [6]. A Sb2Te3 thin film as a saturable absorberwas used to develop a stable Q-switch vortex laser. Depending on the pump power level (whichwas done at 808 nm with a Ti:sapphire laser), laser pulses with durations between 54.7 ns and18.9 ns were obtained, the repetition rate increasing from 21.7 kHz to 103.6 kHz. This method ofgenerating vortex laser beams may lead to the realization of on-chip integrated pulsed lasers.The characteristics of the first deep-red europium planar waveguide laser were described byBaillard et al. [7]. Liquid phase epitaxy was employed to obtain 100-µm thick heavily-doped11.5-at.% Eu:KY(WO4)2 layers on undoped bulk KY(WO4)2 substrates, using K2W2O7 as asolvent; by polishing at laser-grade quality, the thickness of the layer has been reduced to 30 µm.The principal refractive indices of both the undoped substrate and Eu3+-doped epitaxial layerwere measured. Confocal laser microscopy was employed to investigate the layer morphology.Polarized absorption spectra in the blue-green spectral range and luminescence spectra in thevisible spectral range of Eu3+ ions in the grown epitaxial layers were determined. The Euwaveguide was pumped at 532 nm and delivered a maximum output power of 7 mW at 704.7nm for an absorbed pump power of around 100 mW; the slope efficiency was 9.5%, whilethe threshold absorbed pump power amounted to 21 mW. The measurements indicated lowpropagation losses (0.05 dB/cm) in the deep-red spectrum (at 704.7 nm) of the waveguide. PowerIntroduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31207scaling and improvement of the efficiency for this kind of waveguide as well as the manufacturingof ridge-type waveguides, through high-precision mechanical processing, are objectives that willbe considered in future investigations.Kifle et al. have achieved a significant milestone in the advancement of visible fluoride fiberlasers through the use of a Pr:ZBLAN fluoride double-clad fiber [8]. Specifically, a 0.8 mol%PrF3-doped ZBLAN fiber, featuring a 7.5-µm core diameter and a length of 4.7 m, was pumpedusing a high-power fiber-coupled GaN laser module emitting at 442 nm. The Pr-fiber laser systemdemonstrated an output power of 9.1 W at 635 nm in continuous-wave (CW) operation for alaunched pump power of 35.9 W, yielding an overall optical-to-optical efficiency of 25.3% and aslope efficiency of 27%. When operating the pump diode in quasi-CW mode (with a duty cycleof 1:2), the system achieved a peak output power of 10.32 W at 635 nm for a launched pumppower of 41.3 W, resulting in an overall efficiency of 25.0%; the slope efficiency amounted to26.2%. A temperature-dependent spectroscopic analysis of Pr3+ ions in ZBLAN was conducted,demonstrating the capability of these glasses to maintain their spectroscopic properties up to200°C, thereby enabling low-threshold laser operation. Additionally, strategies for further powerscaling are explored.Various laser systems have been used to study, in the last decade, the ignition of differentfuel mixtures. This method of ignition is being investigated to improve combustion, whichis the main process for obtaining energy for humanity, but which also pollutes and generatesgreenhouse gas emissions with negative influences on the environment. Grigore and Pavel [9]used a compact, spark-plug-like Nd:YAG/Cr4+:YAG laser to study laser ignition (LI) of H2/airmixtures in a constant-volume combustion chamber (CVCC). LI was performed at a single point,using a single laser pulse, but also operating the laser in pulse-burst mode with trains of up tofive pulses. The experiments were performed at room temperature, with H2/air mixtures havinga relative equivalence ratio, λ in the range of 1.5 - 5.0 and up to an initial pressure of 9 bar inthe CVCC. It was found that pulse-burst mode LI does not significantly influence the maximumpressure compared to single-pulse LI, but reduces the total combustion time, especially for lean(λ>4.0) H2/air mixtures. Lean ignition limits were determined, noting differences between them,depending on the initial pressure, by using single pulse and pulse-burst LI. The results may beuseful for using H2 in internal combustion engines.The development of the HiPoLas laser ignition system, with emphasis on the recent Vgeneration of this device, is discussed by Kroupa et al. [10]. The results obtained in 10 yearsof investigations in the field of rocket engine LI are mentioned and the recent efforts madeto achieve a fiber-distribution prototype based on diffractive optical elements are discussed.Tests performed on different combustor types and various propellant mixtures are described,as well as considering full-scale rocket engines under flight-like conditions. The technology isnow prepared to pass flight certification tests, with a first flight using this type of laser ignitionexpected in the coming years. The possibility of using multimode optical fibers with a largecladding-to-core ratio for spatial beam division in the ignition of rocket engines was investigatedby Tabakaev et al. [11]. In the experiments, the beam delivered by a compact Hipolas Gen Vlaser (40-mJ maximum pulse energy, 2-ns duration, 1064-nm wavelength) was coupled to suchfibers with different characteristics. A fiber coupling efficiency of nearly 100% and pulse energyof 16.6 mJ was transmitted through a 2 m long fiber (this one with 400-µm diameter core and720-µm cladding) which was bent even at a radius of 0.15 m. Damages of the fiber ends were notobserved after 100 laser pulses. Additional experiments concluded that multimode interferencewithin the fiber is the primary contributor to fiber damage. These results are expected to beuseful in laser systems for rocket engines, by reducing their cost and complexity, but also in otherareas, such as laser-induced breakdown spectroscopy or laser material processing.Many scientific applications, including coherent control of matter, the development ofcompact accelerators and table-top x-rays sources, or the building of ultrafast electron-diffractionIntroduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31208instruments, require the use of high-energy THz radiation. To create energetic sources ofTHz radiation, one can increase the fluence of the drive-laser source, while optimizing thephase-matching process in the nonlinear crystal by fine-tuning the spectral, temporal, and spatialproperties of the laser pulses. In addition, increasing the aperture of the nonlinear medium allowsthe accommodation of high-energy laser pulses, allowing for scaling of the nonlinear process.Matlis et al. report results on high-energy THz generation using large aperture periodically-poled,MgO-doped LiNbO3 (LA-MgO:PPLN), realized as voltage-poled bulk, but also as in-houseassembled, manually-poled wafer-stack structures [12]. THz pulses with over 100 µJ energywere obtained from a large aperture (10 × 15 mm2 area) voltage-poled LA-MgO:PPLN, thisbeing a record for this technique. Cryogenic cooling was implemented, for the first time, toobtain manually-poled wafer-stack MgO-doped LiNbO3 devices, thus reducing THz absorptionfor larger stacks. Potassium titanyl phosphate (KTP) was considered as an alternative material,as it has a high-damage threshold; thus, manually-poled wafer stacks of KTP were tested. Theexperiments yielded THz pulses with 207 µJ energy from wafer-stacked MgO-doped LiNbO3and with energies up to 125 µJ in wafer-stacked KTP. The advantages and disadvantages of bothlarge-aperture approaches are discussed and directions for future experiments are proposed.The transmission spectra in the vacuum-ultraviolet and mid-infrared regions for quartzwere investigated by Ishizuki and Taira [13]. Quasi-phase-matched (QPM) quartz structureswere constructed by a multi-stacking technique and ultraviolet laser emission at 266 nm wasdemonstrated using the pump at 532 nm with pulses of 0.5 ns duration. The aim is to obtainQPM quartz by the multi-stacking method that would be useful for generating THz radiationunder intense laser pumping.Tetrahydrofuran (THF) is a colorless and readily volatile organic solvent, used in the productionof resins, adhesives or detergents, for various coatings, or as battery electrolytes. Xu et al. usedRaman spectroscopy and a two-dimensional correlation Raman analysis to investigate threedistinct bonding states in THF-water solutions of different concentrations [14]. A discussion onthe changes in bond length and angles is made based on density functional theory. The results arehelpful for the development of new applications of THF-water solutions, of interest for scientificstudies or in various other fields.De Vito et al. conducted a detailed study of laser-induced damage in antireflection (AR)coated, large aperture Yb:YAG ceramic media using nanosecond pulses [15]. They used S-on-1and raster scan testing techniques to evaluate the laser-induced damage threshold of various ARcoatings on several Yb:YAG substrates. The study found that a coating’s survival in an ex-situraster scan at 5 J/cm2 fluence correlated with long-term survival in DiPOLE (Diode PumpedOptical Laser for Experiments) amplifiers at fluences up to 3 J/cm2. The results are valuable fordesigning compact amplifier systems capable of operating at high fluence levels.The management of heat generation within laser gain media is essential for the designing andsuccessful realization of high-intensity laser systems. In this process, a thorough understandingof the laser medium’s thermal parameters is of paramount importance. In addition, because alaser can be operated at different temperatures, the way these parameters vary with temperaturemust be evaluated and used appropriately to obtain the expected laser performance. Sato etal. measured the linear thermal expansion, the change of optical path length and the thermaldiffusivity of undoped Y3Al5O12 (YAG) single crystal and ceramics over a wide temperaturerange, 160 K to 500 K [16]. Several thermal properties of YAG, such as the thermal conductivityκ, the linear thermal expansion coefficient α, the temperature coefficient of refractive indexdn/dT, the thermal diffusivity D, and the specific heat Cp were tabulated. In addition, numericalexpressions for these parameters have been proposed for the studied temperature range. Thefollowing studies aim to clarify the dependence of Nd-doping concentration on these parameters,both for single crystal and ceramic Nd:YAG, thus providing a fairly powerful tool for laser design.Introduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 31209Nd3+:YVO4 is a well-established laser medium, known for its favorable spectroscopic andoptical properties, including a high absorption cross-section, broad optical transparency acrossthe 400-5000 nm spectral range, a large effective emission cross-section, and polarized emission.These characteristics make it suitable for the development of microchip lasers. However, theconventional single-crystal growth methods for producing high-quality, large-sized Nd:YVO4crystals are typically complex, difficult to control, and costly. As a result, ceramic processingmethods are being explored as an alternative approach to fabricate transparent Nd:YVO4 lasermedia in larger dimensions. In the case of non-cubic crystal ceramics, which exhibit birefringentscattering at grain boundaries, magnetic field alignment techniques are widely utilized to controlcrystallographic orientation. Liu et al. employed a colloidal processing technique, based onelectrostatic repulsion and/or steric stabilization, to prepare a highly stable and well-dispersedYVO4 nano-powder slurry [17]. This was subsequently used to form a textured YVO4 green bodyvia slip casting under the influence of a magnetic field. The green body was then sintered usingthe spark plasma sintering method. Optical characterization of the resulting ceramics revealedthat transmittance was significantly enhanced through microstructural control enabled by thistexturing approach. The study concluded that this method is also applicable to the orientationcontrol of Nd-doped YVO4 ceramics, which will be the subject of future investigations.The devastating earthquake of March 2011, which struck Japan’s east coast and resulted ina major accident at Fukushima Daiichi Nuclear Power Station (FDNPS), remains a tragic andunforgettable event. For safety, inspections that provide information about the composition ofnuclear elements and their distribution at damaged FDNPS reactors must be done remotely, forexample using a robotic arm. Batsaikhan et al. present the effort made to develop a device thatincludes a laser microchip coupled to a long (>100 m) fiber-optic cable (FOC), of interest forlaser-induced breakdown spectroscopy (LISB) investigation of nuclear fuel debris [18]. Theinfluence of gamma radiation dose on the transmission in the visible and near-infrared (NIR)spectra for FOC with different lengths is investigated. It is shown that FOC with high-OHgroups have higher transmission in a high-radiance environment, compared to FOC with low-OHgroups. It was estimated that a FOC with a length even of 870 m ensures good transmissionof the Nd:YAG/Cr4+:YAG laser radiation (1064 nm wavelength, duration of 800 ps) used inthe experiments. Analysis of Gd in some mixed oxide samples was done for high-OH FOC ofdifferent lengths. A microchip laser-induced breakdown spectroscopy (FC AW-mLIBS) systemcoupled to a 200-m-long high-OH FOC allowed the identification of Gd lines in the visiblespectrum. Qualitative and quantitative analysis were conducted in the NIR spectrum using FOCwith lengths greater than 200 m length, showing no transmission losses over an extended period.We hope that readers will find these articles interesting and are confident that fundamentalresearch and societal applications in the field of solid-state lasers will continue with outstandingresults, some of which may be presented at the TILA-LIC 2025 conference, 23 - 25 April 2025in Pacifico Yokohama, Yokohama, Japan. We would like to thank all the authors and show ourgratitude to the reviewers for their valuable efforts that led to the publication of this issue. Weare also grateful to Mrs. Kelly Cohen and Mrs. Carmelita Washington from the Optica staff forthe exceptional support through the launch of this feature issue, as well as in the review andproduction processes.Disclosures. The authors declare that there are no conflicts of interest related to this article.References1. Y. F. Chen, Y. H. Hsu, S. Q. Lin, et al., “Compact actively Q-switched Nd:YVO4/YVO4 Raman laser at 1525 nmwith frequency up to 150 kHz,” Opt. Express 32(14), 25498–25507 (2024).2. Y. F. Chen, X. W. Chang, S. Q. Lin, et al., “Dual-wavelength solid-state Raman laser at 555 and 579.5 nm forspectrophotometric determination of carboxyhemoglobin,” Opt. Express 32(17), 30335–30343 (2024).3. S. Slimi, H. Yu, H. Zhang, et al., “Growth, structure, spectroscopic, and laser properties of Ho-doped yttrium galliumgarnet crystal,” Opt. Express 33(2), 2529–2541 (2025).https://doi.org/10.1364/OE.530651https://doi.org/10.1364/OE.532533https://doi.org/10.1364/OE.540363Introduction Vol. 33, No. 15 / 28 Jul 2025 / Optics Express 312104. K. Li, Y. Xia, C. Niu, et al., “Influence and regulation of photon de-excitation on thermal energy couplingcharacteristics and dynamic stability boundary of single-doped thulium ion laser,” Opt. Express 33(5), 10621–10636(2025).5. D. W. Kim, S. Won, J.-H. Park, et al., “Sub-picosecond mode-locked laser operation in a femtosecond-laser-inscribedYb:CaF2 channel waveguide,” Opt. Express 32(24), 42801–42809 (2024).6. W. Sun, F. Liu, J. Guan, et al., “Femtosecond laser fabricated semi-tapered waveguide for Q-switched vortex lasergeneration,” Opt. Express 33(2), 1749–1759 (2025).7. A. Baillard, J. E. Bae, M. Ceballos, et al., “Deep-red planar waveguide laser operation of Eu3+:KY(WO4)2 layers,”Opt. Express 33(3), 4926–4939 (2025).8. E. Kifle, A. Baillard, P. Loiko, et al., “10-watt diode-pumped red Pr:ZBLAN double-clad fiber laser,” Opt. Express33(5), 11110–11122 (2025).9. O. V. Grigore and N. Pavel, “Laser ignition of hydrogen/air mixtures in a constant-volume combustion chamberusing a pulse-burst Nd:YAG/Cr4+:YAG laser spark plug,” Opt. Express 32(17), 30344–30359 (2024).10. G. Kroupa, D. Tabakaev, M. Börner, et al., “Overview and recent applications of the miniaturized HiPoLas ignitionsystem,” Opt. Express 32(24), 42289–42300 (2024).11. D. 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