The 810-nm InGaAlAs/AlGaAs double quantum well （QW） semiconductor lasers with asymmetric waveguide structures, grown by molecular beam epitaxy, show high quantum efficiency and high-power conver- sion efficiency at ...The 810-nm InGaAlAs/AlGaAs double quantum well （QW） semiconductor lasers with asymmetric waveguide structures, grown by molecular beam epitaxy, show high quantum efficiency and high-power conver- sion efficiency at continuous-wave （CW） power output. The threshold current density and slope efficiency of the device are 180 A/cm^2 and 1.3 W/A, respectively. The internal loss and the internal quantum efficiency are 1.7 cm^-1 and 93%, respectively. The 70% maximum power conversion efficiency is achieved with narrow far-field patterns.展开更多
The laser-field induced magnon amplification in a magnetic semiconductorquantum well under an external magnetic field was discussed, it is shown that when the laserfrequency is near to the electron cyclotron frequency...The laser-field induced magnon amplification in a magnetic semiconductorquantum well under an external magnetic field was discussed, it is shown that when the laserfrequency is near to the electron cyclotron frequency, no matter how weaker the laser field is, themagnon amplification always occurs. In case of fixed laser frequency, the optical absorption ofmagnons obeys the definite selection rule to the laser field strength. The rate of change of magnonoccupation is calculated, and the amplification condition is given.展开更多
Using beam propagation method （BPM）, key optical design parameters of InP/AlGaInAs multiple quantumwell （MQW） ring laser were numerically analyzed. The influences of waveguide dimensions, curvature radiusand gap s...Using beam propagation method （BPM）, key optical design parameters of InP/AlGaInAs multiple quantumwell （MQW） ring laser were numerically analyzed. The influences of waveguide dimensions, curvature radiusand gap size on the coupling efficiency were discussed. An InP/AlGaInAs MQW ring laser with radius of 350 μm wasdesigned and realized. The experimental results show that the designed device, lasing at 1 563.2 nm with side modesuppression ratio higher than 20 dB, exhibited unidirectional bistability between the clockwise and counterclockwisemodes.展开更多
By analyzing the factors which affect the wall-plug efficiency of semiconductor Laser Diodes (LDs), a high efficiency 1060 nm LD was designed, including active region, waveguide layers, and cladding layers. The simula...By analyzing the factors which affect the wall-plug efficiency of semiconductor Laser Diodes (LDs), a high efficiency 1060 nm LD was designed, including active region, waveguide layers, and cladding layers. The simulation result shows that the component of In in InGaAs in the active region cannot be too small, otherwise the thickness of InGaAs active layer will exceed the critical thickness, meanwhile the asymmetric large optical cavity can decrease the cavity loss effectively. The epitaxial structure was grown by MOCVD, experimental results of varying cavity length showed that the internal quantum efficiency reached 98.57%, and the cavity loss was only 0.273 cm?1. Devices with 4 mm-cavity-length and 100 μm-strip-width were fabricated, 47.4% wall-plug efficiency was reached under QCW pulse condition at room temperature, and the peak wavelength was 1059.4 nm.展开更多
An experimental way for the thermal characterization ofsemiconductor lasers based on I-V method under pulse drivingconditions has been developed, with which the thermal characteristicsof strain compensated 1.3 μm InA...An experimental way for the thermal characterization ofsemiconductor lasers based on I-V method under pulse drivingconditions has been developed, with which the thermal characteristicsof strain compensated 1.3 μm InAsP/InGaAsP ridge waveguide MQW laserchips have been investigated. The results show that, by measuring andanalyzing the I- V characteristics under appropriate pulse drivingconditions at different has sink Temperatures, the thermal resistanceof the laser diodes could be easily deduced. The driving Current andjunction voltage waveforms of the laser ships under different pulsedriving Conditions are also discussed.展开更多
Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity ...Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity surface emitting laser （VCSEL） in detail. Results show that the selective oxidation follows a law which differs from any reported in the literature. Below 435℃ selective oxidation of Al0.98Ga0.02As follows a linear growth law for the two mesa structures employed in VCSEL. Above 435℃ approximately increasing parabolic growth is found, which is influenced by the geometry of the mesa structures. Theoretical analysis on the difference between the two structures for the initial oxidation has been performed, which demonstrates that the geometry of the mesa structures does influence on the growth rate of oxide at higher temperatures.展开更多
It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally diff...It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty h, deriving the parameters relat^i~g to the quantum well structure. In this paper, we describe an efl：icient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AllnGaAs-AIGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs.展开更多
The effect of quantum well number on the quantum efficiency and temperature characteristics of In- GaN/GaN laser diodes （LDs） is determined and investigated. The 3-nm-thick In0.13Ca0.87N wells and two 6-am-thick GaN...The effect of quantum well number on the quantum efficiency and temperature characteristics of In- GaN/GaN laser diodes （LDs） is determined and investigated. The 3-nm-thick In0.13Ca0.87N wells and two 6-am-thick GaN barriers are selected as an active region for Fabry-Perot （FP） cavity waveguide edge emitting LD. The internal quantum efficiency and internal optical loss coefficient are extracted through the simulation software for single, double, and triple InGaN/GaN quantum wells. The effects of device temperature on the laser threshold current, external differential quantum efficiency （DQE）, and output wavelength are also investigated. The external quantum efficiency and characteristic temperature are improved significantly when the quantum well number is two. It is indicated that the laser structures with many quantum wells will suffer from the inhomogeneity of the carrier density within the quantum well itself which affects the LD performance.展开更多
We investigate intersubband Rabi flopping in modulation-doped semiconductor quantum wells with and without the propagation effects, respectively. It is shown that propagation effects have a larger impact on Rabi flopp...We investigate intersubband Rabi flopping in modulation-doped semiconductor quantum wells with and without the propagation effects, respectively. It is shown that propagation effects have a larger impact on Rabi flopping than the nonlinearities rooted from electron-electron interactions in multiple quantum wells. By using ultrashort rr pulses, an almost complete population inversion exists if the propagation effects are not considered; while no complete population inversion occurs in the presence of propagation effects. Furthermore, the magnitude of the impact of propagation effects may be controlled by varying the carrier density.展开更多
文摘The 810-nm InGaAlAs/AlGaAs double quantum well （QW） semiconductor lasers with asymmetric waveguide structures, grown by molecular beam epitaxy, show high quantum efficiency and high-power conver- sion efficiency at continuous-wave （CW） power output. The threshold current density and slope efficiency of the device are 180 A/cm^2 and 1.3 W/A, respectively. The internal loss and the internal quantum efficiency are 1.7 cm^-1 and 93%, respectively. The 70% maximum power conversion efficiency is achieved with narrow far-field patterns.
基金This work was financially supported by National Natural Science Foundation of China (No.10074004)
文摘The laser-field induced magnon amplification in a magnetic semiconductorquantum well under an external magnetic field was discussed, it is shown that when the laserfrequency is near to the electron cyclotron frequency, no matter how weaker the laser field is, themagnon amplification always occurs. In case of fixed laser frequency, the optical absorption ofmagnons obeys the definite selection rule to the laser field strength. The rate of change of magnonoccupation is calculated, and the amplification condition is given.
基金Supported by the National Natural Science Foundation of China(No.61106052)
文摘Using beam propagation method （BPM）, key optical design parameters of InP/AlGaInAs multiple quantumwell （MQW） ring laser were numerically analyzed. The influences of waveguide dimensions, curvature radiusand gap size on the coupling efficiency were discussed. An InP/AlGaInAs MQW ring laser with radius of 350 μm wasdesigned and realized. The experimental results show that the designed device, lasing at 1 563.2 nm with side modesuppression ratio higher than 20 dB, exhibited unidirectional bistability between the clockwise and counterclockwisemodes.
文摘By analyzing the factors which affect the wall-plug efficiency of semiconductor Laser Diodes (LDs), a high efficiency 1060 nm LD was designed, including active region, waveguide layers, and cladding layers. The simulation result shows that the component of In in InGaAs in the active region cannot be too small, otherwise the thickness of InGaAs active layer will exceed the critical thickness, meanwhile the asymmetric large optical cavity can decrease the cavity loss effectively. The epitaxial structure was grown by MOCVD, experimental results of varying cavity length showed that the internal quantum efficiency reached 98.57%, and the cavity loss was only 0.273 cm?1. Devices with 4 mm-cavity-length and 100 μm-strip-width were fabricated, 47.4% wall-plug efficiency was reached under QCW pulse condition at room temperature, and the peak wavelength was 1059.4 nm.
文摘An experimental way for the thermal characterization ofsemiconductor lasers based on I-V method under pulse drivingconditions has been developed, with which the thermal characteristicsof strain compensated 1.3 μm InAsP/InGaAsP ridge waveguide MQW laserchips have been investigated. The results show that, by measuring andanalyzing the I- V characteristics under appropriate pulse drivingconditions at different has sink Temperatures, the thermal resistanceof the laser diodes could be easily deduced. The driving Current andjunction voltage waveforms of the laser ships under different pulsedriving Conditions are also discussed.
文摘Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity surface emitting laser （VCSEL） in detail. Results show that the selective oxidation follows a law which differs from any reported in the literature. Below 435℃ selective oxidation of Al0.98Ga0.02As follows a linear growth law for the two mesa structures employed in VCSEL. Above 435℃ approximately increasing parabolic growth is found, which is influenced by the geometry of the mesa structures. Theoretical analysis on the difference between the two structures for the initial oxidation has been performed, which demonstrates that the geometry of the mesa structures does influence on the growth rate of oxide at higher temperatures.
文摘It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty h, deriving the parameters relat^i~g to the quantum well structure. In this paper, we describe an efl：icient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AllnGaAs-AIGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs.
基金supports from Universiti Sains Malaysia,Ministry of Science Technology and Innovation (MOSTI),Ministry of Higher Education are gratefully acknowl-edged
文摘The effect of quantum well number on the quantum efficiency and temperature characteristics of In- GaN/GaN laser diodes （LDs） is determined and investigated. The 3-nm-thick In0.13Ca0.87N wells and two 6-am-thick GaN barriers are selected as an active region for Fabry-Perot （FP） cavity waveguide edge emitting LD. The internal quantum efficiency and internal optical loss coefficient are extracted through the simulation software for single, double, and triple InGaN/GaN quantum wells. The effects of device temperature on the laser threshold current, external differential quantum efficiency （DQE）, and output wavelength are also investigated. The external quantum efficiency and characteristic temperature are improved significantly when the quantum well number is two. It is indicated that the laser structures with many quantum wells will suffer from the inhomogeneity of the carrier density within the quantum well itself which affects the LD performance.
基金the National Natural Sciences Foundation of China under Grant No.60708008.
文摘We investigate intersubband Rabi flopping in modulation-doped semiconductor quantum wells with and without the propagation effects, respectively. It is shown that propagation effects have a larger impact on Rabi flopping than the nonlinearities rooted from electron-electron interactions in multiple quantum wells. By using ultrashort rr pulses, an almost complete population inversion exists if the propagation effects are not considered; while no complete population inversion occurs in the presence of propagation effects. Furthermore, the magnitude of the impact of propagation effects may be controlled by varying the carrier density.
