Development Of Laser Systems Research Articles

Limitations of beam-control compensation

In this paper, we use wave-optics simulations to explore the limitations of beam-control compensation. We evaluate performance in terms of the normalized power in a diffraction-limited bucket for the cases of no beam-control compensation, perfect phase compensation, and perfect full-field compensation. From these results, we are able to arrive at the following conclusions: (1) without any form of beam-control compensation, performance begins to degrade when D/r0 > 1; (2) with perfect phase compensation, performance begins to degrade when D/r0 > 1 and (λ/r0)/θ0 > 1; and (3) with perfect full-field compensation, performance begins to degrade when D/r0 > 1 and (λ/D)/θ0 > 1. Here, D is the aperture diameter, r0 is the Fried parameter, λ is the wavelength, and θ0 is the isoplanatic angle. We show (1)–(3) to be true for varying aperture diameters, uniformly distributed turbulence, and varying turbulence profiles. These findings will inform the development of future laser systems that need to sense and correct for the effects of atmospheric turbulence.

Development of ultrafast laser system based on Yb-doped fiber and Yb:YAG thin-rod for preclinical study of pigmented lesions treatment using a Hartley guinea pig

Development of ultrafast laser system based on Yb-doped fiber and Yb:YAG thin-rod for preclinical study of pigmented lesions treatment using a Hartley guinea pig

Ultra-smooth processing of lithium niobate for outstanding mid-infrared transmittance.

The fabrication of anti-reflection (AR) subwavelength structures (SWSs) of lithium niobate (LN) is a challenging but rewarding task in mid-infrared LN laser systems. However, there are still some issues with the high-quality processing and fabrication of bifacial AR SWSs. Herein, a novel, to the best of our knowledge, approach to the fabrication of SWSs was proposed, which includes femtosecond laser ablation followed by wet etching and thermal annealing. The fabricated structures exhibit high surface quality (Ra = 0.08 nm) and uniformity. According to the experimental and simulated results, the transmittance of the mid-infrared AR SWSs with a period of 1.8 µm could be improved from 78% to 87% in the 3.6-5 µm band. Furthermore, the double-sided construction enabled a transmittance of up to 90%. The results have great potential in the promotion of the development of mid-infrared laser systems and LN-based photonics.

A Platform for Ultra-Fast Proton Probing of Matter in Extreme Conditions.

Recent developments in ultrashort and intense laser systems have enabled the generation of short and brilliant proton sources, which are valuable for studying plasmas under extreme conditions in high-energy-density physics. However, developing sensors for the energy selection, focusing, transport, and detection of these sources remains challenging. This work presents a novel and simple design for an isochronous magnetic selector capable of angular and energy selection of proton sources, significantly reducing temporal spread compared to the current state of the art. The isochronous selector separates the beam based on ion energy, making it a potential component in new energy spectrum sensors for ions. Analytical estimations and Monte Carlo simulations validate the proposed configuration. Due to its low temporal spread, this selector is also useful for studying extreme states of matter, such as proton stopping power in warm dense matter, where short plasma stagnation time (<100 ps) is a critical factor. The proposed selector can also be employed at higher proton energies, achieving final time spreads of a few picoseconds. This has important implications for sensing technologies in the study of coherent energy deposition in biology and medical physics.

Surface damage induced by micropores in transparent ceramics under nanosecond laser irradiation.

The increasing use of transparent ceramics in laser systems presents a challenge; their low damage threshold has become a significant impediment to the development of powerful laser systems. Consequently, it is imperative to undertake research into the damage sustained by these materials. Micropores, the most common structural defects in transparent ceramics, inevitably remain within the material during its preparation process. However, the relationship between the density and size of these micropores and their impact on nanosecond laser damage threshold and damage evolution remains unclear. In this study, we utilize the annealing process to effectively manage the density and size of micropores, establishing a correlation between micropores in relation to damage thresholds. This study confirms for the first time that micropores significantly contribute to laser damage, comparing and analyzing the damage morphology characteristics of both front and rear surfaces of transparent ceramics. It also presents, potential mechanisms that may contribute to these differences in damage. This paper offers guidance for controlling micropores during the preparation and processing of transparent ceramics with high laser damage thresholds. The findings are expected to further improve the anti-nanosecond laser damage capabilities of transparent ceramics.

Applications of Microstructured Optical Fibers in Ultrafast Optics: A Review

With the development of laser technology, microstructured optical fibers (MOFs) have become an important part of ultrafast optics, providing excellent platforms for ultrafast laser pulse generation, amplification, and compression, promoting the development of fiber laser systems to generate high power, high pulse energy, and few-cycle duration pulses. MOFs extend the ultrafast laser spectrum to the vacuum ultraviolet (VUV) and even extreme ultraviolet (EUV) regions based on dispersive wave emission and high harmonic generation, as well as to the mid-infrared region based on soliton self-frequency shift (SSFS), contributing compact and low-cost light sources for precision microscopy and spectroscopy. In this paper, first several common types of MOFs are introduced, then the various applications of MOFs in ultrafast optics are discussed, mainly focusing on the aspects of ultrafast laser pulse scaling in pulse energy and spectral bandwidth, and finally the possible prospects of MOFs are given.

Wavelength-tunable ultrafast two arm fiber laser system for transient interferometric scattering microscopy on nanoscopic objects

Ultrafast time-resolved microscopy of single nano-objects is particularly challenging because of minute sample volumes and correspondingly small signal levels together with the possibility of photobleaching. We present a compact pulsed two arm fiber laser-based system suited for highly sensitive transient interferometric scattering (TiSCAT) microscopy of nanomaterials. A continuously tunable probe arm is used for spectrally resolved detection of the transient sample response in the range between 810 and 960 nm upon pulsed excitation at 780 nm by the pump arm. Coupled to a scanning confocal microscope with high numerical aperture objective, the system provides spectral maps with sub-300 nm spatial and 300 fs temporal resolution. We tested the platform using monolayer MoSe2 and individual (6,4) single-walled carbon nanotubes as model samples. Confocal microscopy images recorded for an exfoliated monolayer MoSe2 reveal spatially varying excited state decay, highlighting the need for local probing. Spectrally resolved TiSCAT measurements on individual (6,4) single-walled carbon nanotubes show that the transient response is dominated by ground-state bleaching with picosecond recovery times. The obtained data illustrate the excellent noise properties and stability of the newly developed laser system, which allow for nearly shot-noise limited TiSCAT detection at the low probe fluences required for avoiding photodegradation of sensitive nanomaterials.

Investigating surface integrity of laser-machined polycrystalline diamond using a 300 W picosecond laser

Polycrystalline diamond (PCD) is an important material in the tool industry due to its superior wear resistance and strength. Picosecond laser machining enables accurate cutting, geometric profiling, and precise dimensional features to be produced on PCD. The industrialisation of this manufacturing process necessitates the development of laser systems and process strategies that facilitate high throughput and quality. This paper investigates the feasibility of using a 300 W picosecond laser to machine PCD. It examines the influence of fluence, average power, pulse duration and number of passes on the material removal rate and surface quality. The surface integrity after machining is ascertained using a surface profilometer, optical microscopy and Raman spectroscopy. The results have shown that a high material removal rate of 33 mm3/min (0.11 mm3/min W) at a surface roughness of 2.3 μm is achievable using a fluence of 0.9 J/cm2 at 41.3 MHz and 300 W average power. Raman’s analysis of the machined sample suggests a laser-induced graphitisation which is prevalent at high pulse overlap, peak power, and the number of passes. Overall, the study strengthens the idea that with optimised process parameters, a balance is established between productivity and high surface integrity.

Ultra-precision optical processing technology for large-aperture laser optics: Polishing path and technical parameter of arrayed magnetorheological finishing (AMRF)

With the continuous development of high-power laser systems, laser optics gradually changed towards large-aperture, high-quality. To adapt to the fabrication of large-aperture laser optics, a new-type array magnetorheological finishing (AMRF) technique was developed and had made initial progress. However, AMRF technique would introduce more obvious ripple structures (such as 1 mm−1 of spatial frequency) compared to original MRF technique while adopting conventional raster path, and the ripple structures might affect laser beam transmission. For the further application of AMRF technique, the formation mechanism of ripple structures was studied, and a method based on the contour of removal function was proposed to analyze the changes of spatial frequency and evaluate the effect of different polishing paths. According to the analysis method, non-equal-interval parallel raster path was chosen and applied into AMRF process, along with maintaining efficiency while controlling ripple structures. In general, this work could provide a valuable support for the AMRF process of large-aperture laser optics and had a certain significance for the high-power laser system.

OS4 Vitrectomy Device of Oertli

Vitrectomy operations, which started with the construction of the first prototypes of vitrectomy devices in the early 1970s, have become increasingly widespread in parallel with technological developments until today. With the developments in pump systems, lighting systems and laser systems, patient safety and surgeon comfort are increasing. There are many companies producing vitrectomy devices in the market. Each device has some features that are superior to the other. The current vitrectomy device of Oertli, which has been working in this field since the prototype of the first vitrectomy device, is OS4. In this review, we will give information about the OS4 vitrectomy device of Oertli.

Investigation of active laser delivery and antimycotic activity of zinc-containing nanomaterials and photodynamic drugs in the treatment of onychomicosis

One of the most common nail pathologies is onychomycosis, a fungal nail infection. The low efficiency of existing methods for the treatment of onychomycosis stimulates the search for new drugs and technologies for their delivery under the nail plate. The aim of the investigation was to study the possibility of using Er:YLF laser radiation for sequential laser microporation of the human nail plate and active laser delivery of modern photodynamic preparations and zinc-containing nanomaterials under the nail plate, as well as to determine their antimycotic activity against the Candida albicans fungus under photodynamic exposure with a wavelength of 656±10 nm. A 0.001 % aqueous solution of methylene blue, a chlorine-containing Revixan gel, as well as zinc-containing nanomaterials, which are aqueous solutions of polyvinylpyrrolidone gel with different concentrations of Zn(NO3)2 nanoparticles and acidity, were studied. It was established that the smallest number of laser pulses required for in vitro microporation of the nail plate and active laser delivery under the nail plate is required when using a 0.001 % aqueous solution of methylene blue, and the largest is required when using Revixan gel. For zinc-containing nanomaterials, an increase in the concentration of Zn(NO3)2 nanoparticles from 14 to 40 % leads to an increase in the number of laser pulses required for active drug delivery under the nail plate by 1.25 times, while a change in the acidity of the pH gel from 7.0 to 6.7 does not has a significant impact on it. It was found that all the studied drugs in combination with photodynamic action at a wavelength of 656±10 nm have an antimycotic effect on the Candida albicans fungus culture. The minimum growth rate of Candida albicans colonies was observed when using the Revixan gel, for which the antimycotic activity reached 73.8 %. The obtained results can be applied in the development of laser systems and technologies for the treatment of fungal diseases, including for photodynamic therapy of onychomycosis.

Design and Development of a Laser Warning Sensor Prototype for Airborne Application

&#x0D; &#x0D; &#x0D; Due to recent developments in high-energy laser systems, the laser is becoming one of the most potential choices in battlefield applications. Laser of a laser range finder used to find target distance may be of nanosecond pulse width and a single pulse may be sufficient to gather the instantaneous range information. A laser target designator is a similar laser with higher energy and with programmable pulse repetition frequencies5,7. Detection of such a specific battlefield laser radiation along with recognizing friend or foe is required for countermeasures. Designing a laser detection system that is capable of detecting such low-power level laser pulses of nanosecond pulse width at a long distance is a critical design and a challenging task. Again detecting a wide wavelength band that can start from 500 nm to around 1700 nm range using a single detector or device is also a challenging task. In this work, a sensor system is being designed and a prototype is developed to cover such a long band detection using a single detector for high-energy lasers. Also, in addition to detecting hostile code, the direction of an incoming laser beam is tried to incorporate into this sensor. The sensor can be utilized to detect unknown or non-friendly laser illumination from within a specific angular cone and distance.&#x0D; &#x0D; &#x0D;

High peak power and energy scaling in the mid-IR chirped-pulse oscillator-amplifier laser systems.

The paper introduces a new route towards the ultrafast high laser peak power and energy scaling in a hybrid mid-IR chirped pulse oscillator-amplifier (CPO-CPA) system, without sacrificing neither the pulse duration nor energy. The method is based on using a CPO as a seed source allowing the beneficial implementation of a dissipative soliton (DS) energy scaling approach, coupled with a universal CPA technique. The key is avoiding a destructive nonlinearity in the final stages of an amplifier and compressor elements by using a chirped high-fidelity pulse from CPO. Our main intention is to realize this approach in a Cr2+:ZnS-based CPO as a source of energy-scalable DSs with well-controllable phase characteristics for a single-pass Cr2+:ZnS amplifier. A qualitative comparison of experimental and theoretical results provides a road map for the development and energy scaling of the hybrid CPO-CPA laser systems, without compromising pulse duration. The suggested technique opens up a route towards extremely intense ultra-short pulses and frequency combs from the multi-pass CPO-CPA laser systems that are particularly interesting for real-life applications in the mid-IR spectral range from 1 to 20 μm.

Femtosecond laser fabrication of chirped and tilted fiber Bragg gratings for stimulated Raman scattering suppression in kilowatt-level fiber lasers.

Chirped and tilted fiber Bragg gratings (CTFBGs) are important all-fiber filtering components in high-power fiber lasers for stimulated Raman scattering (SRS) suppression. The fabrication of CTFBGs in large-mode-area double-cladding fibers (LMA-DCFs) by femtosecond (fs) laser is reported for the first time to the best of our knowledge. The chirped and tilted grating structure is obtained by scanning the fiber obliquely and moving the fs-laser beam relative to the chirped phase mask at the same time. By this method, the CTFBGs with different chirp rates, grating lengths, and tilted angles are fabricated, and the maximum rejection depth and bandwidth are ∼25 dB and ∼12 nm, respectively. To test the performance of the fabricated CTFBGs, one is inserted between the seed laser and the amplifier stage of a 2.7 kW fiber amplifier, and an SRS suppression ratio of ∼4 dB is achieved with no reduction in laser efficiency and degradation in beam quality. This work provides a highly fast and flexible method to fabricate large-core CTFBGs, which is of great significance to the development of high-power fiber laser systems.

High-efficiency coupled-cavity optical frequency comb generation

We present a high efficiency source of picosecond pulses derived from a dual cavity optical frequency comb generator. This approach overcomes the limitations of single cavity comb generators that are restricted to efficiencies of a few percent. We achieve picosecond pulses with GHz repetition rates offering over a hundred times higher output efficiency than a single cavity design and demonstrate tuning of pulse width by varying the modulation depth of the intra-cavity electro-optic modulator. These results provide a wavelength-agnostic design with a compact footprint for the development of portable picosecond pulsed laser systems for timing, metrology, and LIDAR applications.

Optimization process of spin-coated black phosphorus/polydimethylsiloxane composite on microfiber as saturable absorber for ultrafast photonics

Numerous saturable absorber (SA) fabrication methods have been proposed and employed in the development of ultrafast laser systems, particularly for microfiber-based SAs decorated with various 2D materials. However, the study on microfiber-SA with different transition lengths is still inadequate. This paper focuses on the design and fabrication method of black phosphorus/polydimethylsiloxane composite microfiber-based SA for ultrashort pulse generation. With optimized microfiber-SA dimensions of 30 mm (up/down taper), 1 mm (waist length) and 10 µm (waist diameter), black phosphorus/polydimethylsiloxane composite was spin-coated on the microfiber at 4000 rpm for 6 min. The integration of the microfiber-SA in an erbium-doped fiber laser exhibited pulse duration of 724 fs at center wavelength of 1560.18 nm. This work provides a guideline for the design of microfiber-based SA using spin-coating technique to maximize its laser performances.

A safe way to better vision

AbstractThere are many challenges in the development and production of laser systems for medical applications – and the safety requirements are significant. It is no wonder that medical technology manufacturers choose their suppliers very carefully. WaveLight, a subsidiary of Alcon and a global player in refractive surgery, successfully uses products from MKS Instruments in the development, production and maintenance of its high‐quality laser systems.

Aktuelni hirurški modaliteti lečenja polipa glasnica - mini-pregled

Vocal fold polyps represent one of the most common benign organic disorders affecting the larynx in the general population, and a relatively frequent cause of long-standing hoarseness. The exact etiology is unclear, but poor vocal behavior has been suggested as the principal etiologic factor. Histopathologically they are characterized by various structural alterations in the vocal fold superficial lamina propria, and typical clinical finding is of a solitary, unilateral and well-defined vocal fold lesion. Vocal fold polyps usually require surgical removal using microlaryngoscopy with cold steel excision in general anesthesia, which has been the practice standard for the last 60 years. Microlaryngoscopy offers the surgeon an unparalleled magnified view of the vocal folds and very precise work on a still operative field without a specific time limit. The introduction and technological development of ambulatory endoscopy and various laser systems provided the surgeon with ample therapeutic opportunities, including operating some of the patients in the office setting in local anesthesia. These outpatient procedures are technically simple and cost-effective, require fewer medical personnel, exclude general anesthesia-related risks, and are less time-consuming both for the patient and the physician. Nevertheless, the contemporary laryngologist should be able to perform both conventional microlaryngoscopy and office-based surgery for vocal fold polyps, depending on the clinical situation.

Experimental damage thresholds of a laser suppression imaging system using a cubic phase plate

The development of laser systems leads to an increasing threat to photoelectric imaging sensors. A cubic phase plate wavefront coding imaging system is proposed to reduce the risk of damage owing to intense laser radiation. Based on the wavefront coding imaging model, the diffracted spot profile and the light intensity distribution on the observation plane are simulated. An experimental device is set up to measure the laser-induced damage thresholds and investigate the morphology of laser-induced damage patterns of the conventional and the wavefront encoding imaging system. Simulations and experimental results manifest the superior laser suppression performance of the proposed method, which can help diminish the undesirable effects of laser irradiation on an imaging sensor.

Modeling and Design Methodology for the Development of Electro-Optical and Laser Systems

Modeling and simulation (M&S) plays a key role in the development of all systems, but especially so in the development and integration of electro-optical (EO) subsystems and lasers for precision strike applications or counter measures that require precise pointing control. Since the development of the first EO and laser systems, the directed energy community has pursued an evolving modeling and design (M&D) approach to support the development of these systems to provide the data and insights needed for the acquisition process. M&D is the lower-level detailed engineering models that are used to define and perfect the design (mechanical, optical, electrical, software), whereas M&S is typically the higher-level engagement models embedded in the mission and war game simulations. When the M&S is closely tied to the M&D, the M&S will accurately represent the system capabilities and limitations. This paper presents an M&D methodology that has matured over the past years and continues to be applied on current EO and laser programs. Similar to other development methodologies utilized by government agencies and industry, the M&D methodology is critical for airborne EO-laser systems, where the operating environment is especially hostile to achieving microradian pointing accuracy and jitter stability in the optical line of sight. Applying the M&D methodology early and often throughout the development process in conjunction with the model-based systems engineering approach, the M&S can fully integrate into the life cycle of EO-laser programs from the development of requirements, the verification of design, the prediction and verification of performance, and the defining of system capabilities and limitations, to the maintenance and upgrades to the system. This disciplined connectivity of M&S to the M&D will lead to cost-effective EO-laser systems.