By using poled-polymer/silicon slot waveguides in the active region and the Pockels effect of the poled-polymer,we propose a kind of Mach-Zehnder interferometer(MZI) electro-optic(EO) switch operated at 1 550 nm.Struc...By using poled-polymer/silicon slot waveguides in the active region and the Pockels effect of the poled-polymer,we propose a kind of Mach-Zehnder interferometer(MZI) electro-optic(EO) switch operated at 1 550 nm.Structural parameters are optimized for realizing normal switching function.Dependencies of switching characteristics on the slot waveguide parameters are investigated.For the silicon strip with dimension of 170 nm×300 nm,as the slot width varies from 50 nm to 100 nm,the switching voltage can be as low as 1.0 V with active region length of only 0.17–0.35 mm,and the length of the whole device is only about 770–950 μm.The voltage-length product of this switching structure is only 0.17–0.35 V·mm,and it is at least 19–40 times smaller than that of the traditional polymer MZI EO switch,which is 6.69 V·mm.Compared with our previously reported MZI EO switches,this switch exhibits some superior characteristics,including low switching voltage,compact device size and small wavelength dependency.展开更多
To achieve ultrasonic casting of 35 CrMo steel,the waveguide unit for introducing ultrasound into liquid steel was studied numerically and experimentally.The structure and length of the ultrasonic waveguide were optim...To achieve ultrasonic casting of 35 CrMo steel,the waveguide unit for introducing ultrasound into liquid steel was studied numerically and experimentally.The structure and length of the ultrasonic waveguide were optimized by modal analysis.The simulation results showed that a T-shaped waveguide unit matched the vibrational system better than an L-shaped unit.The performance of T-shaped waveguide unit was optimized when the length of the ultrasound radiator was 135 mm.The performance of the T-shaped waveguide unit was investigated in ultrasonic casting experiments,and the effect of ultrasound on the microstructure of 35 CrMo steel was examined.The experimental results showed that the T-shaped waveguide was able to successfully introduce ultrasound into the 35 CrMo melt.In addition,the use of a silicon nitride ceramic radiator avoided high-temperature corrosion in the molten metal.The microstructure of the treated area was significantly refined and equiaxed grains were obtained.The results represented a novel method for ultrasonic casting of steel.展开更多
In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivi...In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the Ph C leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact Ph C 1.31/1.55 μm wavelength division multiplexer（WDM）/demultiplexer with simple structure is proposed,where the output power ratios are more than 24 d B. This WDM can multiplex/demultiplex other light waves efficiently.展开更多
An In P-based monolithically integrated few-mode transmitter aiming at the combination of wavelength division multiplexing（WDM） and mode division multiplexing（MDM） technologies is proposed. The core elements of th...An In P-based monolithically integrated few-mode transmitter aiming at the combination of wavelength division multiplexing（WDM） and mode division multiplexing（MDM） technologies is proposed. The core elements of the proposed transmitter are mode converters and a wavelength-mode division multiplexer that are all based on multimode interference（MMI） couplers. Simulations show that the wavelength-mode division multiplexer has a large fabrication tolerance of 30 and 0.5 μm for the length and the width of the device, respectively.A low loss below 0.26 dB for the passive parts of the transmitter is obtained in the whole C-band wavelength range.展开更多
The high power and low internal loss 1.06 μm InGaAs/GaAsP quantum well lasers with asymmetric waveguide structure were designed and fabricated. For a 4000 μm cavity length and 100 μm stripe width device,the maximum...The high power and low internal loss 1.06 μm InGaAs/GaAsP quantum well lasers with asymmetric waveguide structure were designed and fabricated. For a 4000 μm cavity length and 100 μm stripe width device,the maximum output power and conversion efficiency of the device are 7.13 W and 56.4%, respectively. The cavity length dependence of the threshold current density and conversion efficiency have been investigated theoretically and experimentally; the laser diode with 4000 μm cavity length shows better characteristics than that with 3000 and 4500 μm cavity length： the threshold current density is 132.5 A/cm^2, the slope efficiency of 1.00 W/A and the junction temperature of 15.62 K were achieved.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61107021,61177027 and 61077074)the Ministry of Education of China(Nos.20110061120052 and 20120061130008)the Science and Technology Department of Jilin Province of China(No.20130522161JH)
文摘By using poled-polymer/silicon slot waveguides in the active region and the Pockels effect of the poled-polymer,we propose a kind of Mach-Zehnder interferometer(MZI) electro-optic(EO) switch operated at 1 550 nm.Structural parameters are optimized for realizing normal switching function.Dependencies of switching characteristics on the slot waveguide parameters are investigated.For the silicon strip with dimension of 170 nm×300 nm,as the slot width varies from 50 nm to 100 nm,the switching voltage can be as low as 1.0 V with active region length of only 0.17–0.35 mm,and the length of the whole device is only about 770–950 μm.The voltage-length product of this switching structure is only 0.17–0.35 V·mm,and it is at least 19–40 times smaller than that of the traditional polymer MZI EO switch,which is 6.69 V·mm.Compared with our previously reported MZI EO switches,this switch exhibits some superior characteristics,including low switching voltage,compact device size and small wavelength dependency.
基金Item Sponsored by National Basic Research Program of China(2014CB046702)
文摘To achieve ultrasonic casting of 35 CrMo steel,the waveguide unit for introducing ultrasound into liquid steel was studied numerically and experimentally.The structure and length of the ultrasonic waveguide were optimized by modal analysis.The simulation results showed that a T-shaped waveguide unit matched the vibrational system better than an L-shaped unit.The performance of T-shaped waveguide unit was optimized when the length of the ultrasound radiator was 135 mm.The performance of the T-shaped waveguide unit was investigated in ultrasonic casting experiments,and the effect of ultrasound on the microstructure of 35 CrMo steel was examined.The experimental results showed that the T-shaped waveguide was able to successfully introduce ultrasound into the 35 CrMo melt.In addition,the use of a silicon nitride ceramic radiator avoided high-temperature corrosion in the molten metal.The microstructure of the treated area was significantly refined and equiaxed grains were obtained.The results represented a novel method for ultrasonic casting of steel.
基金supported by the National Natural Science Foundation of China(No.61405058)the Hunan Provincial Natural Science Foundation of China(No.2017JJ2048)the Fundamental Research Funds for the Central Universities(No.531107050979)
文摘In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the Ph C leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact Ph C 1.31/1.55 μm wavelength division multiplexer（WDM）/demultiplexer with simple structure is proposed,where the output power ratios are more than 24 d B. This WDM can multiplex/demultiplex other light waves efficiently.
基金supported by the National 973 Program of China(No.2014CB340102)the National Nature Science Foundation of China(Nos.61320106013 and61271066)
文摘An In P-based monolithically integrated few-mode transmitter aiming at the combination of wavelength division multiplexing（WDM） and mode division multiplexing（MDM） technologies is proposed. The core elements of the proposed transmitter are mode converters and a wavelength-mode division multiplexer that are all based on multimode interference（MMI） couplers. Simulations show that the wavelength-mode division multiplexer has a large fabrication tolerance of 30 and 0.5 μm for the length and the width of the device, respectively.A low loss below 0.26 dB for the passive parts of the transmitter is obtained in the whole C-band wavelength range.
文摘The high power and low internal loss 1.06 μm InGaAs/GaAsP quantum well lasers with asymmetric waveguide structure were designed and fabricated. For a 4000 μm cavity length and 100 μm stripe width device,the maximum output power and conversion efficiency of the device are 7.13 W and 56.4%, respectively. The cavity length dependence of the threshold current density and conversion efficiency have been investigated theoretically and experimentally; the laser diode with 4000 μm cavity length shows better characteristics than that with 3000 and 4500 μm cavity length： the threshold current density is 132.5 A/cm^2, the slope efficiency of 1.00 W/A and the junction temperature of 15.62 K were achieved.
