The Raman lasing of 107 kW at 1125 nm achieved by the Yb-RFA, leveraging the RRFL's full-open cavity as the seed, operates beyond the operating wavelengths of all reflection components. The Raman lasing exhibits a spectral purity of 947%, and its 3-dB bandwidth spans 39 nm. By merging the temporal steadiness of RRFL seeds with the power enhancement provided by Yb-RFA, this work unlocks the potential for extending the wavelength of high-power fiber lasers while maintaining high spectral purity.
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. This all-fiber laser source generates 28-meter pulses with a consistent average power of 342 Watts, a pulse width 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. In a cascaded fiber structure composed of silica and passive fluoride, a 2-meter ultra-short pulse experienced a soliton self-frequency shift, producing a 28-meter pulse seed as a result. 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 was observed, accompanied by soliton self-compression and spectral widening.
Birefringence and quasi-phase-matching (QPM), along with meticulously calculated crystal angles or periodic poling arrangements, are phase-matching techniques applied in parametric conversion to fulfill the requirement of momentum conservation. In contrast, the utilization of phase-mismatched interactions in nonlinear media featuring large quadratic nonlinear coefficients is presently neglected. Urinary microbiome Our study, for the first time to our knowledge, focuses on phase-mismatched difference-frequency generation (DFG) within an isotropic cadmium telluride (CdTe) crystal, juxtaposing it with birefringence-PM, quasi-PM, and random-quasi-PM DFG processes. A phase-mismatched difference-frequency generation (DFG) process in the long-wavelength mid-infrared (LWMIR) range, spanning 6 to 17 micrometers, is demonstrated using a CdTe crystal. Due to the exceptionally large quadratic nonlinear coefficient (109 pm/V) and superior figure of merit in the parametric process, the output power reaches 100 W, which is on par with, or surpasses, the DFG output from a polycrystalline ZnSe with equivalent thickness employing random-quasi-PM. Demonstrating the feasibility of gas sensing for CH4 and SF6, a proof-of-concept experiment employed the phase-mismatched DFG as a typical application case. Our findings suggest that phase-mismatched parametric conversion effectively generates useful LWMIR power and ultra-broadband tunability without the constraints of polarization, phase-matching angles, or grating period control, thereby simplifying implementation for spectroscopy and metrology.
Through experimentation, we demonstrate a method of enhancing and flattening multiplexed entanglement in four-wave mixing, achieved by substituting Laguerre-Gaussian modes with perfect vortex modes. Throughout the spectrum of topological charge 'l', from -5 to 5, the entanglement degrees associated with orbital angular momentum (OAM) multiplexed entanglement with polarization vortex (PV) modes exceed those of OAM multiplexed entanglement with Laguerre-Gaussian (LG) modes. Importantly, for OAM-multiplexed entanglement with PV modes, there is virtually no change in the degree of entanglement relative to topology values. To put it another way, our experiment simplifies the entangled states of OAM multiplexing, a process currently unavailable using LG modes and the FWM method. read more Furthermore, we empirically quantify the entanglement using coherent superposition of orbital angular momentum modes. Our scheme, as far as we are aware, offers a new platform for constructing an OAM multiplexed system, which may have applications in the execution 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. Adaptive beam shaping, coupled with a femtosecond laser, creates an elliptical focal voxel within the waveguide material inducing various types of single pulse modifications through nonlinear absorption. These modifications are periodically arranged to produce 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. In contrast, the core wavelength of reflection, approximately 1555 nanometers, can be evaluated through the application of an appropriate smoothing algorithm. Mechanical bending of the sample leads to a noteworthy upshift in the Bragg wavelength of the reflected peak, which can be as high as 160 picometers. This showcases the capacity of additively manufactured waveguides to perform functions beyond signal transmission, including sensing.
The important phenomenon of optical spin-orbit coupling is instrumental in fruitful applications. Employing optical parametric downconversion, we investigate the entanglement properties of the total spin-orbit angular momentum. Direct experimental generation of four pairs of entangled vector vortex modes was achieved using a dispersion- and astigmatism-compensated single optical parametric oscillator. This allowed, for the first time, to the best of our knowledge, the characterization of spin-orbit quantum states on the quantum higher-order Poincaré sphere, and the demonstration of the relationship between spin-orbit total angular momentum and Stokes entanglement. Multiparameter measurement and high-dimensional quantum communication are potential applications of these states.
An intracavity optical parametric oscillator (OPO), pumped by a dual-wavelength source, is utilized to demonstrate a low-threshold, continuous-wave, dual-wavelength mid-infrared laser. To achieve a synchronized and linearly polarized output for a high-quality dual-wavelength pump wave, a composite NdYVO4/NdGdVO4 gain medium is selected. In the quasi-phase-matching OPO procedure, the dual-wavelength pump wave's equal signal wave oscillation contributes to a lower OPO threshold. For the balanced intensity dual-wavelength watt-level mid-infrared laser, a diode threshold pumped power of only 2 watts is ultimately obtainable.
The experimental demonstration of a Gaussian-modulated coherent-state continuous-variable quantum key distribution system demonstrated a key rate below the Mbps mark over a 100-kilometer transmission distance. Fiber channel co-transmission of quantum signal and pilot tone, based on wideband frequency and polarization multiplexing methods, ensures efficient noise control. Chemical-defined medium Moreover, a highly precise, data-driven time-domain equalization algorithm is meticulously crafted to counteract phase noise and polarization fluctuations in weak signal-to-noise scenarios. Experimental results for the demonstrated CV-QKD system show an asymptotic secure key rate (SKR) of 755 Mbps, 187 Mbps, and 51 Mbps at transmission distances of 50 km, 75 km, and 100 km, respectively. Experimental evidence demonstrates that the CV-QKD system surpasses the state-of-the-art GMCS CV-QKD results, leading to a substantial increase in transmission distance and SKR, and suggesting its suitability for long-distance and high-speed secure quantum key distribution.
Employing a generalized spiral transformation, we achieve precise high-resolution sorting of orbital angular momentum (OAM) in light using two custom-designed diffractive optical elements. The experimental sorting finesse achieved a significant improvement of approximately two times over previously reported results, reaching 53. These optical elements' utility in optical communication, specifically using OAM beams, readily extends to other fields utilizing conformal mapping.
Employing an Er,Ybglass planar waveguide amplifier and a large mode area Er-doped fiber amplifier, we demonstrate a MOPA system emitting high-energy optical pulses at 1540nm with single-frequency characteristics. The planar waveguide amplifier leverages a double under-cladding and a 50-meter-thick core design to increase output energy, maintaining beam quality. Every 1/150th of a second, a pulse of 452 millijoules energy, characterized by a peak power of 27 kilowatts, is generated, with each pulse lasting 17 seconds. The output beam's waveguide structure is crucial in achieving a beam quality factor M2 of 184 at the maximum pulse energy.
The computational imaging domain holds a captivating fascination with imaging techniques applied to scattering media. Versatility is a key characteristic of speckle correlation imaging-based techniques. Still, the avoidance of stray light within a darkroom is essential, given that ambient light easily interferes with speckle contrast, thereby potentially diminishing the quality of the reconstructed object. We introduce a plug-and-play (PnP) method for the recovery of objects hidden by scattering media, applicable in non-darkroom scenarios. The generalized alternating projection (GAP) optimization methodology, coupled with the Fienup phase retrieval (FPR) method and FFDNeT, forms the basis of the PnPGAP-FPR method. Experimental demonstrations of the proposed algorithm highlight its considerable effectiveness and adaptable scalability, showcasing its potential for practical applications.
For the purpose of imaging non-fluorescent objects, photothermal microscopy (PTM) was invented. The advancement of PTM in the past two decades has enabled its use in material science and biology, particularly in terms of its precision in detecting individual particles and molecules. However, the far-field imaging method PTM's resolution is restricted by the principle of diffraction.