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Mid-IR Laser Generating Ultrasound in a Polyetheretherketone Polymer
摘要： We demonstrate laser ultrasonic generation in polyetheretherketone (PEEK). A middle infrared ZnGeP2 optical parametric oscillator (ZGP-OPO) pumped by a Q-switched Ho:YAG laser is employed as the ultrasonic excitation source. The ZGP-OPO has a spectral range of 3.2–3.4 μm. At an output wavelength of 3.4 μm, the maximum average output power of ZGP-OPO is 3.05 W with a pulse width of 24.3 ns, corresponding to a peak power of approximately 127.5 kW. The ultrasound is generated by the laser converted from 3.2 to 3.4 μm in the PEEK composite. The maximum ultrasonic signal amplitude in PEEK is 33 mV under the condition of thermoelastic excitation at 3.4 μm. Ablation occurs in the CPRF sample when the energy fluence is over 122.45 mJ/cm2. PEEK has a stronger absorption at 3.4 μm and laser-ultrasound generation is influenced by the wavelength of the laser.
关键词： ZGP-OPO,Ho:YAG laser,polyetheretherketone,ultrasound,Mid-IR laser
更新于2025-09-11 14:15:04
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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) - High Repetition Rate, Wavelength-Tunable Mid-IR Source Driven by ps-Pulses from a Ho:YLF Amplifier at 2 μm
摘要： The generation of ultrashort pulses in the mid-infrared (mid-IR) spectral region is highly demanded for a multitude of applications such as spectroscopy, materials processing, or biomolecular and chemical sensing. For many of the aforementioned applications a high pulse repetition frequency (PRF) is desirable, since it reduces measurement time and improves spectroscopic signal-to-noise ratio. However, most of the ultrafast mid-IR sources are limited to a PRF below 10 kHz as they rely on regenerative amplifier-based pump sources for optical parametric chirped pulse amplification (OPCPA) [1-3]. The herein applied Pockels cell represents a bottleneck for PRF tuning usually below 10 kHz. Just recently, we presented a 2-μm, sub-10 ps pulse laser system with millijoule-level pulse energy, which is in principle not limited by the PRF [4]. This laser system benefits from its simplified, compact CPA-free architecture and high efficiency. In this contribution we use a similar laser system as front-end to pump nonlinear ZnGeP2 (ZGP) crystals in order to approach the wavelength range between 2.5 and 9 μm. This compact mid-IR source benefits from the broad spectral and PRF tunability as well as a remarkably simple experimental scheme.
关键词： ultrashort pulses,ZnGeP2 crystals,wavelength-tunable,mid-IR,high repetition rate,Ho:YLF amplifier
更新于2025-09-11 14:15:04
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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) - Non-Linear Propagation of Ultrashort Mid-IR Pulses
摘要： Many atmospheric applications such as free-space communication or spectroscopy require targeted delivery of high-energy ultrashort pulses with a good beam quality. Often atmospheric turbulences complicate this task, causing random variations of the refractive index and resulting in fluctuations of light intensity on the target. Propagation of light in filamentation regime, when intensity is clamped, to a certain extent helps to overtake this problem, but brings ionization-related problems, such as energy loss, temporal pulse splitting, etc. Moreover, maximum peak power (cid:1842)(cid:3043)(cid:3032)(cid:3028)(cid:3038), which can be delivered in a single filament is limited to about ten critical powers of self-focusing (cid:1842)(cid:3030)(cid:3045)(cid:3036)(cid:3047), after which multiple filamentation and hence small-scale beam distortions take place. In the case of Ti:Sapphire drivers delivering 40-fs, 800-nm pulses, the energy in a single filament in air doesn’t exceed 1 mJ, unless special conditions are applied [1]. However, since (cid:1842)(cid:3030)(cid:3045)(cid:3036)(cid:3047)~(cid:2019)(cid:2870) ((cid:2019) is the driver wavelength), essentially more energy can be deposited in a single filament driven by 3.9-μm pulses [2]. Furthermore, mid-IR spectral range is beneficial in virtue of lower ionization rates and higher resistance to modulation instabilities and scattering by natural atmospheric obstacles, such as water droplets [3]. Finally, a unique combination of high atmospheric transparency and anomalous dispersion of air between 3.6-4.2 μm promote an opportunity for a lossless high-energy ultrashort pulse delivery and simultaneous solitonic self-compression [4]. However, multiple molecular resonances responsible for the anomalous dispersion also complicate filamentation dynamics by adding a new channel of energy loss, namely nonlinear enhanced absorption losses [2,5], when mainly stimulated rotational Raman scattering (SRRS) governs spectral dynamics dominated by an essential spectral redshift and immediate absorption of newly generated spectral components by CO2, having vibrational resonance in the vicinity of 4.2 μm. Due to this non-linearly enhanced absorption up to 50% of energy can be lost over several meters of propagation of 30 mJ 130-fs pulses [2]. However, since the intrapulse SRRS is sensitive to a temporal spacing between spectral components, pre-chirping of drivers pulses can help to reduce and control the energy loss. Moreover, we have demonstrated, that a proper choice of the chirp can also lead to ~5-fold self-compression in time and postponed onset of filamentation in space, what fulfils a goal of targeted high-energy ultrashort pulse delivery.
关键词： Ultrashort mid-IR pulses,filamentation,solitonic self-compression,nonlinear propagation,atmospheric applications
更新于2025-09-11 14:15:04
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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) - Comparative Study of Harmonic Generation in Air and Argon in Light Filaments Driven by Circularly Polarized Mid-IR Pulses
摘要： A generation of optical harmonics by circularly polarized light, which is in general forbidden in an isotropic medium, was recently observed in molecular gases where molecules were aligned and oriented by another linearly polarized laser pulse or by pulses with twisted polarization. In order to generate nth-harmonic with circularly polarized light, a molecule has to “absorb” n photons, having the same handedness, and to emit a single nth harmonic photon while fulfilling the energy and the momentum conservation laws, meaning a necessity to excite the molecule to appropriate rotational state. One can do this by means of intrapulse rotational Raman scattering, which prepares the molecule in the excited state through a subsequent absorption of (n-1) same-handed photons. All previously reported experimental studies on circular harmonic generation in molecular gases were performed with visible/near-IR drivers, in either gas jets or in standing cells and with pre-alignment of molecules by an additional laser pulses. Here we report on the studies of self-action of elliptically polarized mid-IR pulses on the generation of low-order harmonics in filaments ignited in air and in argon, representing a molecular and an atomic gas respectively. The harmonics were driven by 20-mJ, sub-100 fs mid-IR pulses, centred at 3.9 μm wavelength. In the experiments filamentation was assisted by focusing light with a spherical mirror of ROC=-2500 mm into an open-end tube, through which Ar gas was flown at slight overpressure. Polarization of the pulses was controlled by a broadband quarter wave plate (QWP). Spectra of 5th and 7th harmonics were recorded after the filaments with a grating spectrometer (HR4000, OceanOptics). Polarization state of the generated harmonics was analysed with a Glan-Taylor polarizer.
关键词： filaments,argon,circularly polarized light,mid-IR pulses,harmonic generation,air
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference Laser Optics (ICLO) - Saint Petersburg, Russia (2018.6.4-2018.6.8)] 2018 International Conference Laser Optics (ICLO) - Mid-IR cathodoluminescence of zinc selenide highly-doped with iron
摘要： The intensity integrated of cathodoluminescence in the middle infrared region of the spectra of ZnSe:Fe crystals with varying iron concentration have been studied. Dependence of decay time on iron concentration has been demonstrated. Experiments were carried out at 77 K and room temperature.
关键词： mid-IR,ZnSe:Fe,cathodoluminescence
更新于2025-09-11 14:15:04
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The effects of strain and composition on the conduction-band offset of direct band gap type-I GeSn/GeSnSi quantum dots for CMOS compatible mid-IR light source
摘要： A type-I band Ge0.75Sn0.25/Ge0.682Sn0.158Si0.16 QD heterostructure is proposed for mid-IR light sources. The effects of strain and composition are theoretically investigated to optimize the band offset of the direct band gap GeSn QDs. It is found that the introduction of tensile strain and Si incorporation in the barrier layers are effective to increase the band offset in the conduction band. Besides, the band offset is expected to increase with the increase of Sn composition in QDs and the size of QDs.
关键词： mid-IR light source,GeSn QD
更新于2025-09-11 14:15:04
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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) - Mid-IR HCPCF Gas-Laser Emitting at 4.6 μm
摘要： Infrared laser sources emitting in the atmospheric transmission window (i.e. the wavelength range of 3-5 μm and 8-13 μm) are of interest in applications such as remote sensing, imaging and free-space communications. Within this context, Inhibited Coupling Hollow Core Photonic Crystal Fibers (IC-HCPCF) offer an interesting platform for gas laser sources, especially for those emitting in spectral ranges where silica-based solid core fiber lasers fail because of the large infrared (IR) absorption losses of the host materials. Indeed, the possibility of filling HCPCF with gases, and combining long gas-light interaction lengths with small modal areas opened new avenues for laser development and nonlinear optics. Furthermore, IC-HCPCFs exhibit particularly weak optical overlap between the guided field and the glass cladding material (typically in the range 10-4-10-6). Consequently, material absorption losses play a minor role in the mid-IR in a few meter-long silica-based IC-HCPCF as demonstrated previously. This suggests that the concept of hollow fiber gas laser (HOFGLAS), which was demonstrated in the visible with I2 and at 3 μm with C2H2 pulsed and CW, can be extended to longer wavelengths. Here, we report on an optically pumped gas-laser based on N2O-filled IC-HCPCF. The pulsed is pumped at 1.517 μm and emits at 4.6 μm with a photon conversion efficiency of 9% and a slope efficiency of 3%.
关键词： 4.6 μm,gas-laser,Mid-IR,HCPCF,N2O,IC-HCPCF
更新于2025-09-11 14:15:04
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Ge-Rich Graded-Index SiGe Alloys: Exploring a Versatile Platform for mid-IR Photonics
摘要： In this paper, the recent progress on a new Ge-rich SiGe platform for mid-IR integrated photonics is presented. Low-loss spiral waveguides working over a broadband wavelength range are discussed, followed by a sensing proof-of-concept using a standalone photoresist with a known spectral absorption pattern. In addition, the development of new mid-IR interferometric devices for wavelength filtering and enhancement of the light-matter interaction are presented. Finally, efficient designs to exploit the third-order nonlinearities in these Ge-rich SiGe waveguides at mid-IR wavelengths are shown. The demonstration of these key building blocks will pave the way towards the implementation of new mid-IR photonic integrated systems with multiple functionalities.
关键词： waveguides,non-linear mid-IR photonics,interferometric optical devices,mid-IR integrated photonics,SiGe alloys,mid-IR spectroscopy
更新于2025-09-09 09:28:46
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Investigation of mid-IR luminescence properties in Dy3+/Tm3+-codoped LaF3 single crystals
摘要： The spectroscopic characteristics of a series of Dy3+/Tm3+-codoped LaF3 single crystals have been studied for mid-IR emissions through Dy3+:6H13/2 → 6H15/2 transition. Optimal mid-IR emission was achieved in 3 at% Tm3+ and 2 at% Dy3+ co-doped LaF3 sample under the excitation of 790 nm. Its emission cross section was calculated to be 2.56×10-21 cm2 at the peak wavelength (2840 nm) with a FWHM of 270 nm, and the fluorescence lifetime was 3.694 ms. The fact of intense 2.84 μm emission was achieved by 790 nm pumping proves the effective energy transfer from Tm3+ to Dy3+ ions. The possible energy transfer routes were analyzed in detail, and the microscopic transfer constants were also estimated based on the phonon-assisted energy transfer theory. As a result, Dy3+/Tm3+-codoped LaF3 single crystal can be a potential medium for mid-IR lasers.
关键词： microscopic transfer constant,Dy3+/Tm3+:LaF3,sensitization mechanism,mid-IR luminescence
更新于2025-09-09 09:28:46