- 标题
- 摘要
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- 实验方案
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Modernization of the Thl-100 Laser System to Produce Powerful Terahertz Radiation
摘要： This paper presents the results of research on parameters of the THL-100 hybrid laser system of the visible spectrum with a view to modernizing it, in order to achieve the boundary parameters required for the pumping of non-linear crystals and production of the unprecedented THz radiation powers. The laser system consists of the Start-480M Ti:Sa starting complex and photodissociation XeF(C-A) amplifier with a 24 cm aperture. After modernization, the starting complex provides the spectrally limited radiation pulse of 60 fs at the first harmonic (950 nm) at energy of 25 mJ and 50 fs at the second harmonic (475 nm) at energy of 10 mJ. In the case of the positively chirped pulse with duration of 50 ps, the energy at the second harmonic is 3 mJ. When amplifying the negatively chirped radiation pulse in the XeF(C-A) amplifier at the wavelength of 475 nm with duration of 1.8 ps, the power of 40 TW is reached, and the maximum energy is 2 J. When amplifying the positively chirped pulse with duration of 50 ps, the highest energy of 3 J is achieved.
关键词： femtosecond complex,second harmonic,laser beam,hybrid laser system,gas amplifier,radiation energy
更新于2025-09-23 15:21:01
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Development of a new multi-mode NIR laser system for photodynamic therapy
摘要： Photodynamic Therapy (PDT) has been used in various fields especially in cancer treatment. In PDT, designing a light source has vital importance in order to achieve a successful treatment. Among the light sources, Lasers are important candidates for their precise wavelengths to activate the photosensitizers (PS), coherent nature and fiber-coupled usage. In order to achieve perfect PDT treatment, the Laser light sources needs to be embedded with high stability current, temperature controllers and closed loop control systems. In this study, a novel Multi-mode PDT Laser system (MPTL) was developed with four different radiation modes. Importantly, Super Pulse Mode (SPM) was implemented for the first time among the PDT Laser systems in the open literature to minimize the thermal damage to the target tissue. The proposed system achieved high optical output stability by precise current and temperature control of the Laser resonator. The MPTL achieved high optical output stability ( ± 1mW) in the range of 0–1500 mW, high wavelength stability ( ± 1nm) at 635 nm, and high temperature stability ( ± 0.2 °C) in all radiation modes. The MPTL system with super pulse mode can be safely used for wide range of PDT clinical applications.
关键词： Pulse mode laser,Photodynamic therapy,PDT light source,NIR,Super-pulse,Laser system,Multi-mode
更新于2025-09-23 15:21:01
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Design of an innovative and self-adaptive-smart algorithm to investigate the structural integrity of a rail track using Rayleigh waves emitted and sensed by a fully non-contact laser transduction system
摘要： The focus of this study is on locating surface and sub-surface defects that occur in rail tracks using Rayleigh waves that were emitted and sensed by a fully non-contact laser transduction system. As the quality of received signals varies with respect to the rail surface characteristics, spotting the reflection from a defect can be extremely challenging. These signals are in general contaminated with noise and have low repeatability that could hinder the proper identification of the defect signal. In view of this, an innovative signal processing technique called a self-adaptive-smart algorithm (SASA) was designed and developed. In SASA, the incident wave that is the first coming wave-packet is taken as a mother wavelet. A library of possible mother wavelets was designed based on the experimental data. As the incident wave for each sensing point varies because of the physical condition of the rail surface and the laser excitation, the algorithm automatically picks the mother wavelet from the library that generates the largest absolute cross-correlation with the incident wave. SASA is found to be able to suppress the unwanted wave packets from the overall signal leaving behind only the incident wave for a healthy specimen, and the incident wave and its reflection from the defect for a damaged specimen. The functioning of the algorithm was successfully tested by carrying out extensive experiments on a real rail track in the presence of different types of surface and sub-surface defects on its head and web. The obtained results prove the effectiveness of using SASA in localizing defects in rails with a marginal error. Notably, the proposed method has benefits such as being self-adaptive, can help suppress high levels of noise, bring the peak of defect reflected wave in the center, and distinguish between a healthy and damaged sample.
关键词： Structural integrity,Subsurface defects,Signal processing,Rail track,Rayleigh wave,Laser system
更新于2025-09-23 15:21:01
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Development of a novel system for in-situ repair of aeroengine airfoil via pulsed laser ablation
摘要： A novel system for performing in-situ micro-machining of aero-engines for repair applications is proposed in this paper. Using Pulsed Laser Ablation (PLA) as material removal technique, surface cracks caused by foreign objects colliding with airfoils are removed by performing a layer-by-layer micro-machining in the area surrounding the damaged zone. Compared to conventional repair performed by micro-grinding, our invasive PLA system demonstrates a similar level of performance, evaluated from the point of view of fatigue strength in the high cycle (> 107) regime. The follow-up fractographic and metallurgical analysis, indicated that although some micro-structural characteristics are different between the repair methods, the incurred surface damage is limited in magnitude to a thin surface layer (< 30 μm) and the influence on fatigue life is comparable. In the last section, a novel prototype system is presented which allows performing the PLA repair in-situ by use of a miniaturized laser scanning head coupled with a flexible mechanical deployment arm. The system has been successfully tested inside a Roll-Royce Trent jet engine; effectively this proves the possibility of performing in-situ laser micro-machining inside complex mechanical systems such as aero-engines, without the need for complex/expensive disassembly.
关键词： Miniaturized laser system,In-situ micro-machining,Pulsed laser ablation,Aeroengines
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Laser system for recording optics
摘要： The development of a modern laser system for recording optics is presented in this research paper. Studying optical components for designing this system by various methods, by calculated methods and by a method of using modern modeling package Zemax, was conducted. The results of the calculations and simulation, which led to the preliminary design of the laser system of optics registration, coincide.
关键词： lenses,emission,photodiode,laser system,field distribution
更新于2025-09-19 17:13:59
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Tumbling object deorbiting using spaceborne laser engagement a?? A CubeSat case study
摘要： This paper demonstrates active space debris removal using spaceborne laser systems. The laser beam and the surface of the target are discretised into multiple rays and finite elements, respectively, for laser-target interaction modelling, in which the laser ablation process is investigated. A high-fidelity attitude/orbit propagator tool is developed to account for both the linear impulse and angular impulse induced by the laser engagement and other perturbations. The laser system is activated only when three switch criteria are satisfied. In numerical simulations, laser pulses from international space station are generated to deorbit a 3U CubeSat with initially tumbling modes. The results validate the effectiveness of deorbiting tumbling CubeSats using spaceborne laser engagement, with the perigee height lowered by approximately 2:4 km in around 30 min after 2 h propagation. It is also found that the laser engagement becomes more effective for an initially faster rotating object.
关键词： Coupled attitude/orbit dynamics,Spaceborne laser system,Tumbling CubeSat,Space debris
更新于2025-09-19 17:13:59
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - The Compact Laser System for Pulsed Optically Pumped Rubidium Atomic Clock
摘要： In this paper, we propose an implementation of the compact laser system for POP rubidium atomic clock. The compact system consists of the miniaturized optical platform and the laser driving and control electronic module, and the two parts with the same length and width are stacked together to ensure the output laser beam is exactly incident to rubidium vapor cell in physics package of the clock. (1) The miniaturized optical system adopts integration design milling all the pedestals of optical components on the bottom board of the platform with a volume of 30cm×17.5cm×5.8cm. It mainly includes a DBR diode laser as laser source, AOM as optical switching, sub-Doppler spectroscopy optical path, and optical expansion lens. (2) Laser driving and control electronic module mainly includes the high-precision driving current source, temperature control module, and the lock-in module (including PI and the error signal demodulating module). The temperature of the laser diode is set to 20.1℃, with ±0.001℃ fluctuation and the injected current is set around 180.2mA, with ±0.001mA control precision. The power of output laser is 40mW, with diameter 15mm. With sub-Doppler spectroscopy, the laser has been locked to rubidium transition line (795nm) more than 30 days and relocked within 1 second under unattended laboratory conditions, with power fluctuation less than 0.2% and power stability 5.57×10-4. The experimental results show that the portable compact laser system has strong robustness and reliance, which has an important significance in the engineering process of POP Rb atomic clock.
关键词： compact laser system,laser driving and control electronic module,optical platform,pulsed optically pumped rubidium atomic clock
更新于2025-09-16 10:30:52
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Attainment of a 40 TW peak output power with a visible-range hybrid femtosecond laser system
摘要： We report the results of investigations aimed at raising the peak output power of a THL-100 visible-range hybrid femtosecond laser system based on a XeF(C – A) photodissociation amplifier. The increase in power was achieved due to the shortening of the pulse duration at the system output by broadening the spectral profile of the second harmonic from 5.3 to 8 nm, which takes place in the transformation of a negatively chirped pulse of the fundamental frequency radiation in a nonlinear KDP crystal. After the KDP the radiation pulse was stretched to 1.8 ps in a prism stretcher and amplified in the XeF(C – A) amplifier. The energy obtained at the amplifier output was 1.2 J. After compression of the amplified output pulse, its duration was equal to 29.4 fs, which means that a peak output power of 40 TW was reached at the output of the laser system.
关键词： stretcher,chirped pulse,compressor,Ti : sapphire front end,hybrid laser system,XeF (C – A) photodissociation amplifier
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Dispersive Fourier Transform Based Single-Shot CEP Drift Measurement at Arbitrary Repetition Rate
摘要： In recent years attosecond science motivated the development of laser systems, which provide millijoule energy level few-cycle pulses. These experiments rely on a field with stable amplitude and carrier envelope phase (CEP) to provide reproducible results [1]. As a consequence, diagnostic devices, which are capable of single-shot CEP measurement and pulse tagging, became a must-have equipment in today’s laser systems. The self-referenced interferometry such as f-to-2f [2] are one of the most typical way to characterize the shift of the CEP in a single-shot manner. The highest achievable recording rate is mostly limited by the measurement times of the optical spectroscopes, which can only reach 10 kHz even with fast detector array. Dispersive Fourier Transform (DFT) [3,4] can be used to bypass this limitation, so single-shot recordings of the output signal of an f-to-2f interferometer becomes possible even at high repetition rates. The method depends on an optical element with enough dispersion to stretch to pulse duration up to the nanosecond range. Therefore, the spectral modulation pattern containing the encoded CEP appears in the temporal domain, which allows for tracking with a relatively slow photodetector. To demonstrate the validity and performance of this concept, a CEP drift measurement was performed on the state-of-the-art mid-infrared (MIR) laser system at ELI-ALPS [5], which provides mid-IR laser pulses at 100 kHz. As a comparison, an alternative measurement was performed in parallel with a grating spectrometer (Fringeezz, Fastlite) [6] at 10 kHz sampling rate. The two recorded signals were synchronized and a decimated 10 kHz subset was extracted, where correlation between measurements is the highest. One of the main limitation of the DFT method originates from the time jitter between the output of the laser and the TTL signal used for triggering. This time jitter changes the time delay of the modulation pattern, creating an additional noise source for the measured relative CEP value. In order to perform truly time jitter-free single-shot CEP drift measurement, an additional CEP independent spectral modulation was introduced, which can be used to determine the noise originating from the jitter. The jitter-free decimated dataset against the grating spectrometer measurement is displayed on Fig. 1. The calculated CEP noises are summarized in Table 1. These values agree within the limit of the uncertainty of these measurements, validating that this new CEP drift measurement method is easily scalable to arbitrary repetition rates.
关键词： high repetition rate,mid-infrared laser system,Dispersive Fourier Transform,CEP drift measurement,single-shot
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - CEP-Stabilized, Sub-18 fs, 10 kHz and TW-Class 1 kHz Dual Output Ti: Sa Laser with Wavelength Tunability Option
摘要： Generating energetic, few-cycle laser pulses with stabilized Carrier-Envelope Phase at high repetition rate constitutes a first step to access the ultra-fast dynamics underlying the interaction of matter with intense, ultrashort pulses in attosecond science or high field physics [1-3]. We present here a Ti:Sa based, CEP-stabilized, sub-20fs, 1 kHz / 10 kHz hybrid laser system with an original front-end design, delivering 0.9 TW peak power pulses at 1 kHz and close to 20W average power at 10 kHz. In parallel to this short pulse duration operation mode, it is possible to use the front end to tune its output wavelength within a 90 nm range around 800 nm.
关键词： hybrid laser system,CEP-stabilized,wavelength tunability,Ti:Sa,sub-20fs
更新于2025-09-12 10:27:22