查看更多>>摘要：In this study,a miniature laser frequency stabilization module for cold atom sensing applications was designed and realized.The module can lock the laser frequency to the saturated absorption spectrum of the D2 line of rubidium[Rb]atoms using the frequency modulation spectroscopy method.The module core is a tiny Rb cell,co-packaged with the saturation absorp-tion optical setup,temperature control circuit,and detection circuit through a joint optical-mechanical-electrical design for a total volume of only 40 mm × 15 mm × 30 mm.The frequency fluctuation of the 780 nm laser after frequency stabilization by the module was within 1 MHz over 1000 s,which is adequate for magneto-optical trap experiments.The results verify the feasibility of the module as a frequency reference and provide a light source for portable cold atom sensing devices.
查看更多>>摘要：In this Letter,we realized the phonon-assisted Q-switched laser operation in Yb∶YCOB crystal.Differing from previous laser wavelengths below 1.1 μm,we extended the wavelength to 1130 nm by amplifying multiphonon-assisted electronic transi-tions.At a repetition rate of 0.1 kHz,the laser output power was 82 mW with a pulse width of 466.1 ns,corresponding to a high peak power of 1.76 kW and a single pulse energy of 0.82 mJ,respectively.To the best of our knowledge,this represents the highest pulse energy among all Yb3+-doped crystal lasers at the wavelength beyond 1.1 μm.Such a large pulse energy could be explained by the laser rate-equation theory.These results indicated that the electron-phonon coupling effect not only extends the lasing wavelengths but also enables a fast temporal response to support nanosecond,picosecond,even femto-second pulse laser operation.
查看更多>>摘要：By combining the thermally-induced spectral broadening of Er3+/Yb3+co-doped crystal and the high ratio of cavity gain to loss,a high-power broadband continuously tunable 1.5-1.6 μm laser was successfully demonstrated in an Er:Yb∶YAl3[BO3]4 crystal.End-pumped by a continuous-wave 975.6 nm laser diode,three discrete tunable laser bands at 1483-1488,1495-1503,and 1521-1612 nm were realized at an incident pump power of 7.7 W.The maximum continuously tunable bandwidth was 91 nm at 1521-1612 nm,and the maximum output power was 474 mW at 1551 nm.The output power was generally higher than 100 mW in the whole tunable range.
查看更多>>摘要：We explore for the first time the real-time spectra of dissipative soliton[DS]and noise-like pulse[NLP]inter-switching by adjusting the pump power,as well as the dual-pulse collision dynamics for three modes:dual-NLP,NLP-DS,and dual-DS in a single-/dual-wavelength mode-locked fiber laser.Different types of dual-pulses differ in collision duration.During spectral reconstruction,dual-pulses exchange energy twice due to their respective accumulation dynamics.Additionally,collision-induced soliton explosions have chaotic properties,leading to each collision being random.The experimental results advance the study of the dynamics of different pulse types and also contribute to the conduction of in-depth investigations on dual-comb sources.
查看更多>>摘要：We demonstrate,for the first time and to the best of our knowledge,a continuous-wave and broadly tunable Cr∶ZnSe bulk crystal laser pumped by a Tm∶YLF bulk laser with 1845 nm and 1887 nm wavelengths.We compare the output characteristics and wavelength-tuning properties of the continuous-wave operation at the two pump wavelengths.In the continuous-wave operation,the maximum output power is 1.79 W with a slope efficiency of 28.8％,which is achieved at the pump wavelength of 1887 nm.In addition,a tuning range of～700 nm[696 nm]from 2040 nm to 2736 nm by using a reflective diffraction grating is realized.To the best of our knowledge,this is the widest tuning range realized so far for Cr∶ZnSe bulk crystal tuned by gratings.
查看更多>>摘要：Free-space diffractive neural networks[DNNs]have been an intense research topic in machine learning for image recog-nition and encryption due to their high speed,lower power consumption,and high neuron density.Recent advances in DNNs have highlighted the need for smaller device footprints and the shift toward visible wavelengths.However,DNNs fabricated by electron beam lithography,are not suitable for microscopic imaging applications due to their large sizes,and DNNs fabricated by two-photon nanolithography with cylindrical neurons are not optimal for visible wavelengths,as the high-order diffraction could induce low diffraction efficiency.In this paper,we demonstrate that cubical diffraction neurons are more efficient diffraction elements for DNNs compared with cylindrical neurons.Based on the theoretical analysis of the relationship between the detector area sizes and classification accuracy,we reduced the size of DNNs operating at the wavelength of 532 nm for handwritten digit classification to micrometer scale by two-photon nanolithography.The DNNs with cubical neurons demonstrated an experimental classification accuracy[89.3％]for single-layer DNN,and 83.3％for two-layer DNN with device sizes similar to that of biological cells[about 100 μm × 100 μm].Our results paved the pathway to integrate 3D micrometer-scale DNNs with microscopic imaging systems for biological imaging and cell recognition.
查看更多>>摘要：A simple and robust multiple wavelength frequency stabilization system is demonstrated using a single transfer cavity and a 1062-nm ultra-stable laser for all the lasers used in a mercury optical lattice clock.0ffset sideband locking is employed to tune the laser frequency while dichroic mirrors and differentiated modulation frequencies are utilized for the Pound-Drever-Hall locking of four-color lasers.For the most demanding lasers at 1015 nm and 725 nm,the line width of the beat note is reduced t0 27 kHz and 17 kHz,respectively.The frequency fluctuation for the transfer-locked 1015-nm laser is less than 10 kHz,which is much better than the lasers locked to an atomic spectrum.Using its high stability of 5 × 10-12 over 100 s,the transfer-locked 1015-nm laser is employed for low-noise frequency modulated saturated absorption spectroscopy.This approach could also be used in various situations for the research of optical clocks,Rydberg atoms,laser cooling of molecules,and quantum computation with neutral atoms.
查看更多>>摘要：The X-ray free-electron laser[XFEL],a new X-ray light source,presents numerous opportunities for scientific research.Self-amplified spontaneous emission[SASE]is one generation mode of XFEL in which each pulse is unique.In this paper,we propose a pinhole diffraction method to accurately determine the XFEL photon energy,pulses'photon energy jitter,and sample-to-detector distance for soft X-ray.This method was verified at Shanghai soft X-ray Free-Electron Laser[SXFEL].The measured average photon energy was 406.5 eV,with a photon energy jitter[root-mean-square]of 1.39 eV,and the sample-to-detector distance was calculated to be 16.61 cm.
查看更多>>摘要：The diffractive optical element[DOE]is an important component of three-dimensional[3D]imaging systems based on struc-tured light.In this work,we designed the metasurface-driven D0Es based on generalized Rayleigh-Sommerfeld diffraction theory to project large field of view[FOV]pseudo-random dot array for 3D imaging.We measured an efficiency of 61.04％and root-mean-square error[RMSE]of 0.45 for the 60° FOV sample and an efficiency of 42.96％and RMSE of 0.75 for the 144° FOV sample.Because the pattern is designed based on the generalized Rayleigh-Sommerfeld diffraction theory,the projected pattern is similar to the target pattern and has even intensity.
查看更多>>摘要：The study of strong coupling between photonic cavities and excitons has brought about significant advances,varying from fundamental physics to applied science.However,there are several challenges hindering its further development,including obtaining photonic modes with both low room-temperature loss and high electric field[EF]enhancements,the difficulty of precisely transferring exciton materials into the photonic cavity,and the urgent need for additional manipulation approaches.In order to overcome these challenges simultaneously,we present a theoretical strong coupling system based on the chiral metasurfaces that are built by the excitonic van der Waals material of WSe2 and can support the quasi-bound states in the continuum[q-BIC]mode.The q-BIC mode can sustain EF enhancements over 80 times with loss smaller than 10 meV,and the strong coupling between q-BIC mode and WSe2 excitons can be naturally realized without material trans-ferring.Furthermore,a large chirality beyond 0.98 can be obtained in this strong coupling system,making the circular polarization of excitation light an effective parameter to control the generation of coherent states in this metasurface system.Our results can benefit the further development of strong coupling research,shedding light onto the exploration of new quantum devices.
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