查看更多>>摘要：An 8-channel hybrid-integrated chip for 200 Gb/s(8 × 25 Gb/s)signal transmission has been demonstrated.The channels are all within the 0-band,and with a spacing of 800 GHz.The core of this chip is a monolithic integrated multi-wavelength laser array of 8 directly-modulated distributed feedback(DFB)lasers.By using the reconstruction equivalent chirp tech-nique,multi-wavelength integration and asymmetric phase shift structures are achieved in the laser array.The output laser beams of the array are combined by a planar light-wave circuit,which is hybrid-integrated with the laser array by photonic wire bonding.Experiment results of this transmitter chip show good single-mode working of each unit laser,with a side-mode suppression ratio above 50 dB,and the modulation bandwidth is above 20 GHz.Clear eye diagrams are obtained in the lasers for 25 Gb/s non-return-to-zero modulation,which implies a total 200 Gb/s transmission rate for the whole chip.
查看更多>>摘要：The evolution dynamics of mode locking for a solid-state femtosecond Yb∶KGW laser is demonstrated and detected with time-stretch dispersive Fourier transform(DFT)technique for the first time,to the best of our knowledge.The Yb∶KGW laser is constructed first with a classical X-shaped cavity,and SESAM-assisted Kerr lens mode locking is obtained.Then,a DFT device is built to record the buildup and extinction dynamics of the mode-locked laser.The results suggest that the time of extinction is slightly shorter than the buildup time and both of them experience complex transitions.The results indicate that DFT could also be suitable to detect the transient buildup and extinction process in solid-state lasers,which would help investigate both the evolution of mode locking and characteristics determination for solid-state lasers.
查看更多>>摘要：We demonstrated an actively acousto-optic Q-switched pulsed laser based on Pr∶YLF at 604 nm.A 604 nm continuous-wave(CW)laser with a maximum output power of 3.84 W was achieved for the first time,to the best of our knowledge.The Q-switched laser with a maximum average output power of 0.384 W,a narrowest pulse duration of 44.5 ns,a maximum single pulse energy of～64.1 μJ,and a maximum peak power of～1.44 kW was obtained at a repetition rate of 6 kHz.As far as we know,this was the first report of such a narrow pulse duration,high-power,and high-energy Q-switched pulsed laser at 604 nm.The beam quality factors M2 and My2 were measured to be 2.87 and 2.40,respectively.The results show that acousto-optic Q-switching is a promising method for obtaining pulsed lasers.
查看更多>>摘要：Lasers from 1I6 to 3F4 transitions were first demonstrated in a Pr3+∶YLF crystal by inserting a birefringent filter.Output powers up to 2.44 W,2.10 W,2.01 W,and 2.42 W were obtained at 691.7 nm,701.4 nm,705.0 nm,and 708.7 nm,respectively.Their slope efficiencies were 19.8％,16.5％,15.8％,and 19.4％,respectively.The M2 and My2 factors were measured to be 2.29 and 2.03 at 691.7 nm,2.23 and 1.86 at 701.4 nm,2.31 and 2.08 at 705.0 nm,and 2.41 and 2.04 at 708.7 nm,with corresponding power fluctuations of less than 5.3％,5.6％,5.8％,and 2.9％.
查看更多>>摘要：We report on a compact,high-efficiency mid-infrared continuous-wave(CW)Fe∶ZnSe laser pumped by a 2.9 μm fiber laser under liquid nitrogen cooling.A maximum output power of 5.5 W and a slope efficiency of up to 66.3％with respect to the launched pump power were obtained.The overall optical-to-optical(OTO)conversion efficiency,calculated from the output of the 2.9 μm fiber laser to the 4 μm laser,was as high as～54.5％.The OTO efficiency and the slope efficiency are,to the best of our knowledge,the highest ever reported in Fe∶ZnSe lasers.A rate-equation-based numerical model of CW operation was established,and the simulation agreed well with the experiment,identifying the routes used in the experiment for such high efficiency.
查看更多>>摘要：Pulse duration is considered as one of the most important characteristics of high-power femtosecond lasers.However,pulses output from the laser system are susceptible to ambient changes and manifest the instability of pulse durations in an open environment.In this paper,incorporating the algorithmic framework of the improved stochastic hill-climbing search and incremental proportional-integral controller,temperature-induced fluctuations of pulse duration can be effec-tively compensated by an automatic feedback control in an all-fiber chirped-pulse amplification system.In the experiment,sub-hundred femtosecond fluctuation of pulse duration is introduced to verify the performance robustness of the proposed pulse-duration feedback control(PDFC).The stability of pulse duration is obviously higher than the case without the feed-back control,and the peak-to-peak fluctuation of pulse duration is reduced to 6.5％.Furthermore,the robust switching between different pulse durations proves the versatility of the PDFC.We expect that the proposed feedback control method could provide a novel insight into high-power femtosecond lasers widely applied in fundamental researches and industrial fields.
查看更多>>摘要：The existing single-crystal slicing techniques result in significant material wastage and elevate the production cost of premium-quality thin slices of crystals.Here we report(for the first time,to our knowledge)an approach for vertical slicing of large-size single-crystal gain materials by ultrafast laser.By employing aberration correction techniques,the optimi-zation of the optical field distribution within the high-refractive-index crystal enables the achievement of a continuous laser-modified layer with a thickness of less than 10 μm,oriented perpendicular to the direction of the laser direction.The compressed focal spot facilitates crack initiation,enabling propagation under external forces,ultimately achieving the successful slicing of a Φ12 mm crystal.The surface roughness of the sliced Yb:YAG is less than 2.5 μm.The results illustrate the potential of low-loss slicing strategy for single-crystal fabrication and pave the way for the future develop-ment of thin disk lasers.
查看更多>>摘要：A4×112 Gb/s hybrid-integrated optical receiver is demonstrated based on the silicon-photonic vertical p-i-n photodetector and silicon-germanium transimpedance amplifier.We propose a photonic-electronic co-design technique to optimize both the device-level and system-level performance,based on the end-to-end equivalent circuit model of the receiver.Continuous-time linear equalization and shunt peaking are employed to enhance the frequency response.Experimental results reveal that the optical-to-electrical 3-dB bandwidth of the receiver is 48 GHz.Clear open NRZ eye diagrams at 56 Gb/s and PAM-4 eye diagrams at 112 Gb/s are achieved without an equalizer in the oscilloscope.The measured bit error rates for 56 Gb/s in NRZ and 112 Gb/s in PAM-4 reach 1×10-12 and 2.4×10-4(KP4-FEC:forward error correction)thresholds under-4 dBm input power,respectively.Furthermore,the proposed receiver boasts a power consumption of approximately 2.2 pJ/bit,indicating an energy efficient solution for data center traffic growth.
查看更多>>摘要：Recently,the Fano resonance has played an increasingly important role in improving the color performance of structural colors.In this study,we further elucidate the asymmetric spectral shape generated by Fano resonance from a phase per-spective and explore four distinct continuum state structures.By integrating the proposed cavity-like structure with a metal-dielectric-metal discrete state,multilayered thin-film structural colors with minimal background reflection,as low as 8％,were successfully achieved.The reflection peak of this structure exhibits a bandwidth of approximately 50 nm and reaches up to 80％,indicating heightened saturation and color brightness.Moreover,by adjusting the thickness,we effortlessly obtained a broader color gamut compared to Adobe RGB(45.2％),covering 56.7％of the CIE color space.Even adjusting a single layer can achieve a color gamut of 47.1％.In experiments,by deliberately choosing low oxygen-dependent materials,excellent RGB colors with high brightness and in high consistency with simulation results were successfully achieved.Therefore,the scheme's simple process for structural color creation,along with its excellent color performance and the ability to effectively replicate simulation characteristics makes it highly valuable in fields like anti-counterfeiting,decoration,display devices,and solar cell panels.
查看更多>>摘要：The optoelectronic performance of quantum cascade detectors(QCDs)is highly sensitive to the design of the energy level structure,leading to the inability of a single structure to achieve broad wavelength tuning.To address this issue,we propose and demonstrate a modular concept for very long wave infrared(VLWIR)QCDs based on a miniband diagonal transition scheme.The modular design makes the wavelength tuning only need to be adjusted for the absorption quantum well module rather than for the whole active region.Theoretical simulation shows that the wavelength tuning range is 39.6 meV(～14-30 μm).To prove the feasibility of the scheme,three samμles with different absorption well widths were fabricated and characterized.At 10 K,the response wavelengths of the three QCDs are 14,16,and 18 μm,respectively,corresponding to responsivities and detectivities exceeding 2 mA/W and 1 × 1010 Jones.
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