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- 摘要
- 关键词
- 实验方案
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High-power long-wave infrared laser based on polarization beam coupling technique
摘要： We demonstrated a high-power long-wave infrared laser based on a polarization beam coupling technique. An average output power at 8.3 μm of 7.0 W was achieved at a maximum available pump power of 107.6 W, corresponding to an optical-to-optical conversion of 6.5%. The coupling ef?ciency of the polarization coupling system was calculated to be approximately 97.2%. With idler single resonance operation, a good beam quality factor of ～1.8 combined with an output wavelength of 8.3 μm was obtained at the maximum output power.
关键词： optical parametric ampli?er,long-wave infrared laser,polarization coupling,optical parametric oscillator
更新于2025-09-23 15:21:01
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High Conversion Efficiency, Mid-Infrared Pulses Generated via Burst-Mode Fiber Laser Pumped Optical Parametric Oscillator
摘要： We present a mid-infrared optical parametric oscillator (OPO) with a high pump-to-idler conversion efficiency from 1.06 μm to 3.8 μm, which was quasi-synchronously pumped by a burst-mode fiber laser. The pump pulse was specially designed with a rectangular profile in temporal, which was composed of hundreds of ultrashort sub-pulses. By applying the quasi-synchronous pumping scheme, the buildup time of the parametric signal pulse could be minimized. No back-conversion effect was observed when the pump peak power was increased. A maximum pump-to-idler conversion efficiency of 19.6% was achieved when the number of intra-burst sub-pulses was set to be 240. By increasing the number of intra-burst sub-pulses to be about 480, the maximum average output power of 7.9 W at 3.8 μm was realized under pump power of 45.3 W. The corresponding pump-to-idler conversion efficiency was computed to be about 17.5%. The experimental results show an improvement of 40% in pump-to-idler conversion efficiency for this quasi-synchronously pumped OPO when compared with the conventional long laser pulse pumped OPO.
关键词： burst-mode fiber laser,quasi-synchronously pumped,mid-infrared,optical parametric oscillator
更新于2025-09-19 17:13:59
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Efficient and tunable 1.6-μm MgO:PPLN optical parametric oscillator pumped by Nd:YVO4/YVO4 Raman laser
摘要： A highly-efficient tunable 1.6 μm MgO:PPLN-OPO, which we believe to be the first one pumped by a diode-end-pumped Raman laser, is demonstrated. A good beam-quality of actively Q-switched Nd:YVO4/YVO4 Raman laser at 1176 nm and a good mode matching of the whole system resulted in a high-performance OPO. The highest Raman-to-signal conversion efficiency was 49.5% at 1638.8 nm when the incident Raman power was 2 W. The maximum output power of 3.2 W at 1663.5 nm with the pulse-width of 2.85 ns was obtained pumped by 7.57-W Raman laser. Meanwhile, the linewidth was less than 0.3 nm and a high beam quality with M2 factor of 1.92 was obtained.
关键词： Raman pumping,1.6-μm laser,Optical parametric oscillator.,Beam quality
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) - Live Multi-Color Coherent Raman Imaging Enabled by Millisecond Wavelength Tuning
摘要： We present multi-color coherent Raman imaging (CRI) with a frame rate of 8 Hz and rapid wavelength tuning within only 5 ms between successive images, enabled by a novel fiber optical parametric oscillator (FOPO). In CRI the limited tuning speed of conventional laser systems (>1 s) prevents the acquisition of successive images per second at more than one vibrational resonance and is considered as a bottleneck for multi-color assessments of medical specimen and rapidly evolving samples, such as living cells. Recent approaches to CRI with wavelength switching on a timescale of (sub-) milliseconds were based on two synchronized oscillators [1], being limited to two resonances, and parallel laser amplifiers [2] or spectral focusing techniques [3], both the latter with a limited tuning bandwidth of less than 300 cm-1. In contrast, the energy difference of the pump and Stokes pulses, emitted by the here presented FOPO, is tunable across the wide spectral range between 865 and 3050 cm-1 within only 5 ms. Assuming an equal time span for tuning and acquisition, up to 100 user-selectable vibrational components could be imaged per second, when imaging with 100 frame/s. The rapid tuning was achieved by a novel tuning concept for OPOs, based on the dispersive matching of the repetition frequency change of the pump pulses to the associated repetition frequency change of the resonant signal pulses in the FOPO. No alteration of the FOPO, e.g., via a mechanical delay line [4], was required for tuning the signal wavelength and the light source could be composed of all-spliced fiber components. Compared to previously presented FOPOs, the system runs at a high repetition rate of 40 MHz. The pump and Stokes pulses exhibit equal durations of 7 ps and an average power of 500 and 200 mW, respectively. As a first proof-of concept of the CRI capabilities, Fig. 1 shows three images of a sample consisting of water, oil and beads of PMMA and PS, taken successively with an acquisition time of 125 ms for each frame, limited only by the sampling rate of our detection setup. The energy difference was tuned in a frame-by-frame manner between 2850, 2950 and 3050 cm-1 in a time of 5 ms, a negligible time span compared to the acquisition time.
关键词： vibrational resonance,living cells,medical specimen,rapid wavelength tuning,fiber optical parametric oscillator,multi-color coherent Raman imaging
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) - Degenerate Mirrorless Optical Parametric Oscillator
摘要： A mirrorless optical parametric oscillator (MOPO) is a very special class of optical parametric oscillators, where the feedback for oscillation is realized by counter-propagating second-order nonlinear interaction without a need for external mirrors. This arrangement makes the MOPO a very simple, self-aligned and robust oscillator. The MOPO was first proposed theoretically in 1966 [1] however its realization was only possible using the quasi-phase matching (QPM) approach due to requirement for compensation of large momentum mismatch in such interactions [2]. Realization of first-order counter-propagating parametric oscillation requires structures with periodicity in the sub-μm range, which poses substantial fabrication challenges. In addition to its self-aligned nature, MOPO offers unique spectral properties [3], whereby the spectral contents of the pump are transferred to the forward wave, while the backward wave remains narrowband. So far, only nondegenerate MOPO oscillation has been demonstrated. However, it has been theoretically proposed that a degenerate MOPO could be used to realize a high-brightness biphoton source for quantum optics applications [4]. In this work we report on the first realization of the degenerate MOPO generating counter-propagating signal and idler in the spectral band of optical communications. The MOPO was realized in periodically poled Rb-doped KTiOPO4 (PPRKTP) with a QPM period of 420 nm. The structure was fabricated by the coercive field engineering technique [5]. First, the crystals were patterned using a UV laser interference lithography. Then a coercive field grating was created by periodic ion-exchange. Finally, the crystals were poled using planar electrodes. The resulting domain pattern shows excellent uniformity over the whole crystal aperture, and a duty cycle close to 50% (see Fig 1(a)). The optical surfaces of the crystals were polished at an angle to prevent Fresnel-reflection feedback into the MOPO.
关键词： degenerate MOPO,Rb-doped KTiOPO4,mirrorless optical parametric oscillator,counter-propagating parametric oscillation,quasi-phase matching
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) - Optical Vortex Generation from an Anti-Resonant-Ring Picosecond Optical Parametric Oscillator
摘要： Optical vortices are beams with screw like (helical) phase variation along the propagation direction. This phase variation is given by exp(imθ) in the azimuthal plane, where m is the charge of optical vortices. Due to the doughnut shape intensity distribution and orbital angular momentum (OAM) content, optical vortices have found applications in various fields of science and technology. Commercially available mode converters transforming Gaussian beam into vortices suffer from the common drawback of low power handling capabilities and/or narrow wavelength coverage. To avoid such limitations, here we present a new technique of generating high power optical vortices over a wide wavelength range by using a Gaussian beam pumped anti-resonant-ring (ARR) optical parametric oscillator (OPO) [1]. By controlling the superposition of the Gaussian beams of an intracavity ARR, we have generated first-order HG modes [2] and further transformed into optical vortices using cylindrical lens [3], providing tunability across1457 nm to 1647 nm with an output power as high as 539 mW
关键词： optical parametric oscillator,optical vortices,orbital angular momentum,wavelength coverage,anti-resonant-ring
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) - Generation of Multiple Up-Converted OAM States from a Tunable Optical Vortex Parametric Laser Source
摘要： Optical vortices with a ring-shaped spatial form and an orbital angular momentum (OAM) of ?φ, arising from their helical wavefronts characterized by an azimuthal phase, exp(i?φ) (where ? is an integer termed the topological charge), have been widely exploiting a variety of research fields. These include optical trapping and manipulation, fluorescent microscopes with a high spatial resolution beyond the diffraction limit and materials processing. The aforementioned applications strongly desire wavelength-tunability and OAM-versatility to optical vortex sources. In this presentation, we report on the first generation of a signal output having multiple up-converted OAM states with ?(cid:3046) =3~5 (higher OAM than that of pump) from a nanosecond 2nd-order vortex (?(cid:3043) = 2) pumped singly resonant optical parametric oscillator (OPO) with a simple compact cavity configuration. The resulting idler exhibited negative OAM states with ?(cid:3036) =-1~-3.
关键词： Orbital angular momentum,OAM states,Wavelength-tunability,Optical vortices,Optical parametric oscillator
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) - Compact Photoacoustic Spectrometer Based on a Widely Tunable Mid-Infrared Pulsed Optical Parametric Oscillator
摘要： For highly sensitive and selective photoacoustic (PA) trace-gas sensing it is desirable to use high power light sources with large wavelength tunability in the mid-infrared (MIR) region, where most molecules have strong vibrational transitions. The OPO technology is an old technology, but still an excellent choice as light source for PA spectroscopy. The advantages are their molecular specificity due to large wavelength tunability (1.5 to 5μm), high energy output, cost-effectiveness and compactness [1]. The tunability of OPOs together with PA allow for multi-gas detection of several components with common signal processing and data analysis. MIR OPOs can operate in different configurations both pulsed and continuous wave (CW). The pulsed operation results in high peak power, potentially nonlinear absorption effects and a normalized noise equivalent absorption that is not extreme. We demonstrate a novel miniaturized PA trace gas analyzer platform integrated with a MIR OPO targeting the major market opportunity of environmental monitoring and breath analysis [2,3]. We demonstrate that a miniaturized photoacoustic spectroscopic (PAS) cell can be excited resonantly with the MIR OPO by adjusting the laser pulse repetition rate to match the acoustic resonance of the PAS cell. The application of the gas sensor for real time environmental measurements and breath analysis is demonstrated using three samples of gas concentration; 100 ppmV of methane (CH4), 100 ppmV of nitrogen dioxide (NO2), and approximately 1000 ppmV ammonia (NH3) in atmospheric air with a humidity of 40% [3]. A gas flow rate of 300 ml/min through the PAS cell was applied for the three samples. These gases are well-known environmental trace gases and biomarkers in exhaled breath. The gases cause environmental degradation through their effects on soil acidification, eutrophication, and stratospheric ozone depletion. The presence of ammonia in the environment is mainly due to the degradation of animal waste, industrial processes and diesel exhaust. NO2 is a toxic gas and a regulated air pollutant that possess a serious risk for human health. Monitoring them in human breath is also particularly relevant as they are potential cancer biomarkers. We acknowledge the financial support from EUREKA (Eurostars program: E10589 - PIRMAH) and the Danish Agency for Higher Education.
关键词： photoacoustic spectroscopy,optical parametric oscillator,breath analysis,trace-gas sensing,mid-infrared,environmental monitoring
更新于2025-09-11 14:15:04
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Conditions for optical parametric oscillation with a structured light pump
摘要： We investigate the transverse mode structure of the down-converted beams generated by a type-II optical parametric oscillator (OPO) driven by a structured pump. Our analysis focuses on the selection rules imposed by the spatial overlap between the transverse modes of the three fields involved in the nonlinear interaction. These rules imply a hierarchy of oscillation thresholds that determine the possible transverse modes generated by the OPO, as remarkably confirmed with experimental results.
关键词： structured pump,transverse mode structure,optical parametric oscillator,nonlinear interaction,oscillation thresholds
更新于2025-09-09 09:28:46
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Quantitative Evaluation of Broadband Photoacoustic Spectroscopy in the Infrared with an Optical Parametric Oscillator
摘要： We evaluate the spectral resolution and the detection thresholds achievable for a photoacoustic spectroscopy (PAS) system in the broadband infrared wavelength region 3270 nm to 3530 nm driven by a continuous wave optical parametric oscillator (OPO) with P ≈ 1.26 W. The absorption spectra, IPAS(λi), for diluted propane, ethane and methane test gases at low concentrations (c ～ 100 ppm) were measured for ～1350 discrete wavelengths λi. The IPAS(λi) spectra were then compared to the high resolution cross section data, σFTIR, obtained by Fourier Transform Infrared Spectroscopy published in the HITRAN database. Deviations of 7.1(6)% for propane, 8.7(11)% for ethane and 15.0(14)% for methane with regard to the average uncertainty between IPAS(λi) and the expected reference values based on σFTIR were recorded. The characteristic absorption wavelengths λres can be resolved with an average resolution of δλres ～ 0.08 nm. Detection limits range between 7.1 ppb (ethane) to 13.6 ppb (methane). In an additional step, EUREQA, an artificial intelligence (AI) program, was successfully applied to deconvolute simulated PAS spectra of mixed gas samples at low limits of detection. The results justify a further development of PAS technology to support e.g., biomedical research.
关键词： photoacoustic spectroscopy,optical-parametric oscillator,PAS,gas sampling,hydrocarbons,spectral deconvolution,EUREQA,OPO
更新于2025-09-04 15:30:14