The Yb-RFA, using the RRFL with a fully open cavity as the Raman source, achieves 107 kW of Raman lasing at 1125 nm, a wavelength that surpasses the operational range of all reflective components. The spectral purity of the Raman laser is 947%, and its 3-dB bandwidth is precisely 39 nm. The combination of RRFL seeds' temporal stability and Yb-RFA's power amplification capabilities allows for the extension of the wavelength of high-power fiber lasers, thus maintaining their exceptional spectral purity in this work.
An ultra-short pulse, all-fiber master oscillator power amplifier (MOPA) system, 28 meters in length, is reported, seeded by a soliton self-frequency shift originating from a mode-locked thulium-doped fiber laser. With an all-fiber construction, this laser source emits 28-meter pulses, presenting an average power of 342 Watts, a pulse duration of 115 femtoseconds, and a pulse energy of 454 nanojoules. We show, to the best of our knowledge, a breakthrough in all-fiber, femtosecond, watt-level, 28-meter laser systems. Employing a cascaded structure comprising silica and passive fluoride fiber, a 2-meter ultra-short pulse underwent a soliton self-frequency shift, ultimately yielding a 28-meter pulse seed. We fabricated and used a novel, high-efficiency, compact home-made end-pump silica-fluoride fiber combiner in this MOPA system, to the best of our knowledge. Nonlinear amplification of the 28-meter pulse demonstrated soliton self-compression and concurrent spectral broadening.
Parametric conversion necessitates phase-matching, accomplished through techniques like birefringence and quasi-phase-matching (QPM), implemented with carefully calculated crystal angles or periodic polarities to maintain momentum conservation. Undeniably, the utilization of phase-mismatched interactions in nonlinear media with significant quadratic nonlinear coefficients remains largely unexplored. click here We present, for the first time to our knowledge, a study of phase-mismatched difference-frequency generation (DFG) in an isotropic cadmium telluride (CdTe) crystal, juxtaposing this with comparable DFG processes based on birefringence-PM, quasi-PM, and random-quasi-PM. An ultra-broadband spectral tuning difference-frequency generation (DFG) source operating in the long-wavelength mid-infrared (LWMIR) region, from 6 to 17 micrometers, is realized using CdTe. The parametric process's excellent figure of merit, coupled with a substantial quadratic nonlinear coefficient of 109 pm/V, enables an output power of up to 100 W, a performance on par with or surpassing the DFG output from a polycrystalline ZnSe of equivalent thickness, using random-quasi-PM. A proof-of-concept demonstration, focusing on gas sensing of CH4 and SF6, is undertaken utilizing the phase-mismatched DFG as a prime example of its application. Phase-mismatched parametric conversion, as demonstrated by our results, offers a practical method for producing useful LWMIR power and ultra-broadband tunability, dispensing with the necessity of controlling polarization, phase-matching angles, or grating periods, suggesting applications in spectroscopy and metrology.
Our experimental findings showcase a method for augmenting and flattening multiplexed entanglement in the four-wave mixing process, achieved through the replacement of Laguerre-Gaussian modes with perfect vortex modes. When considering topological charge 'l' from -5 to 5, orbital angular momentum (OAM) multiplexed entanglement with polarization vortex (PV) modes displays a consistently higher entanglement degree compared to OAM multiplexed entanglement with Laguerre-Gaussian (LG) modes. For OAM multiplexed entanglement involving PV modes, the degree of entanglement demonstrates an almost negligible change as the topology value fluctuates. Our experimental approach homogenizes the OAM entanglement structure, unlike in LG mode-based OAM multiplexed entanglement using the FWM method. mediating role Furthermore, we empirically quantify the entanglement using coherent superposition of orbital angular momentum modes. Our scheme provides a new platform, as far as we know, for the construction of an OAM multiplexed system, which may find use in the implementation of parallel quantum information protocols.
The integration of Bragg gratings within aerosol-jetted polymer optical waveguides, as produced by the optical assembly and connection technology for component-integrated bus systems (OPTAVER), is demonstrated and analyzed. A femtosecond laser, coupled with adaptive beam shaping, sculpts an elliptical focal voxel within the waveguide material, inducing diverse single pulse modifications due to nonlinear absorption, arrayed to form periodic Bragg gratings. Integration of a grating structure, singular or in an array of Bragg gratings, into the multimode waveguide leads to a substantial reflection signal with multimodal traits. This involves multiple reflection peaks with shapes distinct from Gaussian. While the principle wavelength of reflection is approximately 1555 nm, it is subject to evaluation by use of an appropriate smoothing procedure. The application of mechanical bending results in a notable upshift of the Bragg wavelength of the reflected peak, with a maximum displacement of 160 picometers. These additively manufactured waveguides exhibit versatility, enabling their use in signal transmission and sensing applications.
Optical spin-orbit coupling's significance as a phenomenon is evident in its fruitful applications. We examine the entanglement of spin-orbit total angular momentum during optical parametric downconversion. Employing a dispersion- and astigmatism-compensated single optical parametric oscillator, the experiment generated four entangled vector vortex mode pairs directly. Furthermore, it, to the best of our knowledge, pioneered the characterization of spin-orbit quantum states on the quantum higher-order Poincaré sphere, illustrating the relationship between spin-orbit total angular momentum and Stokes entanglement. Multiparameter measurement and high-dimensional quantum communication are potential applications of these states.
A demonstration of a dual-wavelength, low-threshold mid-infrared continuous wave laser is presented, achieved through the implementation of an intracavity optical parametric oscillator (OPO) that is pumped by a dual-wavelength source. A composite gain medium, comprised of NdYVO4 and NdGdVO4, is used to generate a high-quality dual-wavelength pump wave, outputting a linearly polarized and synchronized signal. In the quasi-phase-matching OPO procedure, the dual-wavelength pump wave's equal signal wave oscillation contributes to a lower OPO threshold. Attaining a diode threshold pumped power of only 2 watts represents a key accomplishment for the balanced intensity dual-wavelength watt-level mid-infrared laser.
A sub-Mbps key generation rate was experimentally observed during the transmission of a Gaussian-modulated coherent-state continuous variable quantum key distribution system over a 100-kilometer optical fiber. Noise mitigation is achieved through co-transmission of the quantum signal and pilot tone in the fiber channel, employing the methodologies of wideband frequency and polarization multiplexing. Immunomicroscopie électronique Finally, a highly accurate data-driven time-domain equalization algorithm is thoughtfully implemented to effectively counter phase noise and polarization variations in low signal-to-noise environments. The CV-QKD system's asymptotic secure key rate (SKR) was found to be 755 Mbps, 187 Mbps, and 51 Mbps in experimental trials, across transmission distances of 50 km, 75 km, and 100 km, respectively. The CV-QKD system's experimental results markedly outperform the current GMCS CV-QKD standard, exhibiting improvements in both transmission distance and SKR, thereby suggesting its applicability to secure quantum key distribution over extended distances and high speeds.
The generalized spiral transformation, implemented through two specially designed diffractive optical elements, allows for high-resolution sorting of light's orbital angular momentum (OAM). Approximately two times better than the previously reported results, the experimental sorting finesse is quantified at 53. These optical elements, crucial for optical communication employing OAM beams, will find widespread use in fields that leverage conformal mapping.
The demonstration of a master oscillator power amplifier (MOPA) system, featuring an Er,Ybglass planar waveguide amplifier and a large mode area Er-doped fiber amplifier, produces single-frequency, high-energy optical pulses at 1540nm. To bolster the output energy of a planar waveguide amplifier, a 50-meter-thick core structure and a double under-cladding are strategically applied, while ensuring the integrity of the beam quality. A pulse of 452 millijoules energy, characterized by a peak power of 27 kilowatts, is produced at a pulse repetition rate of 150 hertz and a pulse duration of 17 seconds. Additionally, the waveguide configuration of the output beam yields a beam quality factor M2 of 184 at maximum pulse energy levels.
The field of computational imaging is deeply engaged with the fascinating subject of imaging via scattering media. Speckle correlation imaging methods have demonstrated a remarkable adaptability. Even so, to maintain the integrity of the reconstruction, a darkroom environment without any stray light is necessary because the speckle contrast is extremely sensitive to ambient light, which can lead to a reduction in the quality of the object being reconstructed. This report details a plug-and-play (PnP) algorithm that reinstates objects obscured by scattering media in a non-darkroom setting. The PnPGAP-FPR method is formulated using a combination of the Fienup phase retrieval (FPR) technique, the generalized alternating projection (GAP) optimization methodology, and FFDNeT. The proposed algorithm's experimental demonstration reveals a significant effectiveness and flexible scalability, implying substantial potential for practical applications.
To image non-fluorescent entities, photothermal microscopy (PTM) was formulated. PTM's capacity for single-particle and single-molecule detection has developed considerably over the past two decades, leading to its increasing utilization in both the fields of material science and biology. Yet, PTM, a far-field imaging procedure, exhibits resolution that is restricted by the limits imposed by diffraction.