Directly modulated 850-nm vertical-cavity surface-emitting lasers(VCSELs)with the advantages of low cost,high modulation speed,good reliability,and low power consumption,are the key sources in the optical interconnect...Directly modulated 850-nm vertical-cavity surface-emitting lasers(VCSELs)with the advantages of low cost,high modulation speed,good reliability,and low power consumption,are the key sources in the optical interconnects with multimode fibers for the supercomputers,data centers,and machine learning applications[1−3].Typically,non-return-tozero(NRZ)modulation format is used.展开更多
Vertical-cavity surface-emitting lasers(VCSELs) are the ideal optical sources for data communication and sensing.In data communication, large data rates combined with excellent energy efficiency and temperature stabil...Vertical-cavity surface-emitting lasers(VCSELs) are the ideal optical sources for data communication and sensing.In data communication, large data rates combined with excellent energy efficiency and temperature stability have been achieved based on advanced device design and modulation formats. VCSELs are also promising sources for photonic integrated circuits due to their small footprint and low power consumption. Also, VCSELs are commonly used for a wide variety of applications in the consumer electronics market. These applications range from laser mice to three-dimensional(3 D) sensing and imaging, including various 3 D movement detections, such as gesture recognition or face recognition. Novel VCSEL types will include metastructures, exhibiting additional unique properties, of largest importance for next-generation data communication, sensing, and photonic integrated circuits.展开更多
Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transforma...Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic compression.The Ti-5553 alloy was heat-treated at 900℃ (almost 50℃ above beta transus temperature)for one hour of soaking time followed by air quenching to achieve a fullyβphase field.After that,Dynamic compression(DC)by Split Hopkinson Pressure Bar(SHPB)and Quasi-static compression(QSC)were performed at a strain rate of~10^3)/s and 10^(-3)/s,respectively.Recovered specimens were thoroughly examined by using different tools,such as an Optical microscope(OM),Scanning electron microscope(SEM),High-resolution transmission electron microscope(HRTEM),and Electron backscatter diffraction(EBSD)to get the reliable data for justification of logical conclusions.It is found that the dominating mode of deformation was dislocation slip along with twinning({332}<113>)to some extent in both of QSC and DC,but sliding&spalling of the grain boundary is observed more in the former.Stress-induced phase transformation,i.e.,βtoα"andβtoω,took place in the grains saturated with dislocation slips,where the former transformation occurred simultaneously with{332}<113>twinning,whileβtoωtransformation was completed when a set of two adjacent(110)_(β)planes covered±1/6th of the total separation distance between two(next to each other)(111)_(β)planes,by equal but opposite shear in(111)_(β)direction,and it caused 3%shrinkage of two closed packed(110)_(β)planes after transformation.展开更多
We experimentally demonstrate for the first time to our knowledge electrically injected vertical-cavity surfaceemitting lasers(VCSELs) with post-supported high-contrast gratings(HCGs) at 940 nm. The HCG-VCSELs have tw...We experimentally demonstrate for the first time to our knowledge electrically injected vertical-cavity surfaceemitting lasers(VCSELs) with post-supported high-contrast gratings(HCGs) at 940 nm. The HCG-VCSELs have two posts to support the air-suspended HCGs, which are realized by simple fabrication without critical point drying. The HCG-VCSEL achieves a threshold current of about 0.65 m A and a side-mode suppression ratio of 43.6 d B under continuous-wave operation at 25℃. Theoretically the HCG-VCSEL with a λ∕2-cavity for the transverse magnetic polarization has a smaller effective mode length of 1.38 ·(λ∕n). Thus, the relaxation resonance frequency can be increased by 16% compared with that of the conventional VCSEL. The modulation speed of 100 Gbit/s for the HCG-VCSEL is expected in the on–off keying modulation format. Our easy design of HCGVCSELs has great potential for applications in optical interconnects, sensing, illumination, and so on.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62075209,62275243,and 61675193)the Beijing Natural Science Foundation(No.Z200006).
文摘Directly modulated 850-nm vertical-cavity surface-emitting lasers(VCSELs)with the advantages of low cost,high modulation speed,good reliability,and low power consumption,are the key sources in the optical interconnects with multimode fibers for the supercomputers,data centers,and machine learning applications[1−3].Typically,non-return-tozero(NRZ)modulation format is used.
基金National Natural Science Foundation of China(NSFC)(61675193)Pioneer Hundred Talents Program,Chinese Academy of Sciences(CAS)+1 种基金Collaborative Research Center(Sonderforschungsbereich-SFB)787,Deutsche Forschungsgemeinschaft(DFG)Distinguished Fellowship of the President of the Chinese Academy of Sciences
文摘Vertical-cavity surface-emitting lasers(VCSELs) are the ideal optical sources for data communication and sensing.In data communication, large data rates combined with excellent energy efficiency and temperature stability have been achieved based on advanced device design and modulation formats. VCSELs are also promising sources for photonic integrated circuits due to their small footprint and low power consumption. Also, VCSELs are commonly used for a wide variety of applications in the consumer electronics market. These applications range from laser mice to three-dimensional(3 D) sensing and imaging, including various 3 D movement detections, such as gesture recognition or face recognition. Novel VCSEL types will include metastructures, exhibiting additional unique properties, of largest importance for next-generation data communication, sensing, and photonic integrated circuits.
基金the financial assistance of the State Key Laboratory of explosion science and technology China (Grant No.YBKT17-06)
文摘Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic compression.The Ti-5553 alloy was heat-treated at 900℃ (almost 50℃ above beta transus temperature)for one hour of soaking time followed by air quenching to achieve a fullyβphase field.After that,Dynamic compression(DC)by Split Hopkinson Pressure Bar(SHPB)and Quasi-static compression(QSC)were performed at a strain rate of~10^3)/s and 10^(-3)/s,respectively.Recovered specimens were thoroughly examined by using different tools,such as an Optical microscope(OM),Scanning electron microscope(SEM),High-resolution transmission electron microscope(HRTEM),and Electron backscatter diffraction(EBSD)to get the reliable data for justification of logical conclusions.It is found that the dominating mode of deformation was dislocation slip along with twinning({332}<113>)to some extent in both of QSC and DC,but sliding&spalling of the grain boundary is observed more in the former.Stress-induced phase transformation,i.e.,βtoα"andβtoω,took place in the grains saturated with dislocation slips,where the former transformation occurred simultaneously with{332}<113>twinning,whileβtoωtransformation was completed when a set of two adjacent(110)_(β)planes covered±1/6th of the total separation distance between two(next to each other)(111)_(β)planes,by equal but opposite shear in(111)_(β)direction,and it caused 3%shrinkage of two closed packed(110)_(β)planes after transformation.
基金National Natural Science Foundation of China(62075209,61675193)Beijing Natural Science Foundation(Z200006).
文摘We experimentally demonstrate for the first time to our knowledge electrically injected vertical-cavity surfaceemitting lasers(VCSELs) with post-supported high-contrast gratings(HCGs) at 940 nm. The HCG-VCSELs have two posts to support the air-suspended HCGs, which are realized by simple fabrication without critical point drying. The HCG-VCSEL achieves a threshold current of about 0.65 m A and a side-mode suppression ratio of 43.6 d B under continuous-wave operation at 25℃. Theoretically the HCG-VCSEL with a λ∕2-cavity for the transverse magnetic polarization has a smaller effective mode length of 1.38 ·(λ∕n). Thus, the relaxation resonance frequency can be increased by 16% compared with that of the conventional VCSEL. The modulation speed of 100 Gbit/s for the HCG-VCSEL is expected in the on–off keying modulation format. Our easy design of HCGVCSELs has great potential for applications in optical interconnects, sensing, illumination, and so on.
