On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Helsenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the syste...On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Helsenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission llne are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission llne, but also dependent on the quantized character of the charge obviously.展开更多
The characteristics of electron transmission through C70 molecule bridge in which two atomic chain leads are connected to long-axis carbon atoms are investigated theoretically by using tight-binding approach based on ...The characteristics of electron transmission through C70 molecule bridge in which two atomic chain leads are connected to long-axis carbon atoms are investigated theoretically by using tight-binding approach based on the Green's function with only one π orbital electron per carbon atom. Electron transmission through C70 molecule from the input to the output terminal is obtained. From the spectrum, the switching feature of the electron transmission through C70 is found, and the oscil-lation property based on the quantized level is explained. The quantum current distributions inside C70 molecule bridge are calculated and simulated by the quan-tum current density theory based on Fisher-Lee formula at the energy point E = -0.2 eV, where the transmission spectrum shows a peak. The maximum and the mini-mum bond quantum currents are presented, and the reason why the currents are distributed nonuniformly is explained by the phase difference of the atomic orbits. The result shows that the currents at each atomic site agree with Kirchhoff quan-tum current conservation law.展开更多
Heat generated by electric current in a quantum dot device contacting a phonon bath is studied using the non- equilibrium Green function technique. Spin-polarized current is generated owing to the Zeeman splitting of ...Heat generated by electric current in a quantum dot device contacting a phonon bath is studied using the non- equilibrium Green function technique. Spin-polarized current is generated owing to the Zeeman splitting of the dot level. The current's strength and the spin polarization are further manipulated by changing the frequency of an applied photon field and the ferromagnetism on the leads. We find that the associated heat by this spin- polarized current emerges even if the bias voltage is smaller than the phonon energy quanta and obvious negative differential of the heat generation develops when the photon frequency exceeds that of the phonon. It is also found that both the strength and the resonant peaks' position of the heat generation can be tuned by changing the value and the arrangement configurations of the magnetic moments of the two leads, and then provides an effective method to generate large spin-polarized current with weak heat. Such a result may be useful in designing low energy consumption spintronic devices.展开更多
Spin-polarized current generated by thermal bias across a system composed of a quantum dot (QD) connected to metallic leads is studied in the presence of magnetic and photon fields. The current of a certain spin ori...Spin-polarized current generated by thermal bias across a system composed of a quantum dot (QD) connected to metallic leads is studied in the presence of magnetic and photon fields. The current of a certain spin orientation vanishes when the dot level is aligned to the lead's chemical potential, resulting in a 100% spin-polarized current. The spin-resolved current also changes its sign at the two sides of the zero points. By tuning the system's parameters, spin-up and spin-down currents with equal strength may flow in opposite directions, which induces a pure spin current without the accompany of charge current. With the help of the thermal bias, both the strength and the direction of the spin-polarized current can be manipulated by tuning either the frequency or the intensity of the photon field, which is beyond the reach of the usual electric bias voltage.展开更多
Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the...Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current js,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current js,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current js,xy is greater than that on the spin current js,yx. The strength of the Rashba spin-orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the. spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.展开更多
我们理论上调查在有联合的弱 Dresselhaus 纺纱轨道的一根量电线中的电流连接了到二正常导体的旋转。量电线和售票员被一个难墙的限制潜力描述。用在量电线和旋转电流的一个新定义中的电子波浪功能,我们计算了线性旋转电流密度 j <...我们理论上调查在有联合的弱 Dresselhaus 纺纱轨道的一根量电线中的电流连接了到二正常导体的旋转。量电线和售票员被一个难墙的限制潜力描述。用在量电线和旋转电流的一个新定义中的电子波浪功能,我们计算了线性旋转电流密度 j <SUB 的元素> s , x i </SUB><SUP > T </SUP>和 j <SUB > s , yi </SUB><SUP > T </SUP>( i = x , y ,z)。我们发现元素 j <SUP > T </SUP><SUB > s , x x </SUB>和 j <SUP > T </SUP><SUB > s , yy </SUB>有反对称的关系和元素 j <SUP > T </SUP><SUB > s , yz </SUB>作为 j <SUB 有一样的数量水平> s , x x </SUB><SUP > T </SUP>和 j <SUB > s , yy </SUB><SUP > T </SUP>。我们也发现一张网线性旋转电流密度,它在量电线的中心有山峰。线性旋转电流能导致的网一个线性电场,它可以暗示旋转电流的一个方法察觉。展开更多
We analyze the transport through asymmetric double quantum dots with an inhomogeneous Zeeman splitting in the presence of crossed dc and ac magnetic fields. A strong spin-polarized current can be obtained by changing ...We analyze the transport through asymmetric double quantum dots with an inhomogeneous Zeeman splitting in the presence of crossed dc and ac magnetic fields. A strong spin-polarized current can be obtained by changing the dc magnetic field. It is mainly due to the resonant tunnelling. But for the ferromagnetic right electrode, the electron spin resonance also plays an important role in transport. We show that the double quantum dots with three-level mixing under crossed dc and ac magnetic fields can act not only as a bipolar spin filter but also as a spin inverter under suitable conditions.展开更多
In this paper,the frequency-locking and threshold current-lowering effects of a quantum cascade laser are studied and achieved.Combined with cavity-enhanced absorption spectroscopy,the noninvasive detection of H_2 wit...In this paper,the frequency-locking and threshold current-lowering effects of a quantum cascade laser are studied and achieved.Combined with cavity-enhanced absorption spectroscopy,the noninvasive detection of H_2 with a prepared concentration of 500 ppm in multiple dissolved gases is performed and evaluated.The high frequency selectivity of 0.0051 cm^-1 at an acquisition time of 1 s allows the sensitive detection of the(1-0) S(l) band of H_2 with a high accuracy of(96.53±0.29)%and shows that the detection limit to an absorption line of 4712.9046 cm^-1 is approximately(17.26±0.63) ppm at an atmospheric pressure and a temperature of 20 ℃.展开更多
The spin current in a parabolically confined semiconductor hcterojunction quantum wire with Drcsselhaus spinorbit coupling is theoretically studied by using the perturbation method. The formulae of the elements for li...The spin current in a parabolically confined semiconductor hcterojunction quantum wire with Drcsselhaus spinorbit coupling is theoretically studied by using the perturbation method. The formulae of the elements for linear and angular spin current densities are derived by using the recent definition for spin current based on spin continuity equation. It is found that the spin current in this Dresselhaus spin-orbit coupling quantum wire is antisymmetrical, which is different from that in Rashba model due to the difference in symmetry between these two models. Some numerical examples for the result are also demonstrated and discussed.展开更多
We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the thre...We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.展开更多
The ground-state entanglement associated with a three-spin transverse Ising model is studied. By introducing an energy current into the system, a quantum phase transition to energy-current phase may be presented with ...The ground-state entanglement associated with a three-spin transverse Ising model is studied. By introducing an energy current into the system, a quantum phase transition to energy-current phase may be presented with the variation of external magnetic field; and the ground-state entanglement varies suddenly at the critical point of quantum phase transition. In our model, the introduction of energy current makes the entanglement between any two qubits become maximally robust.展开更多
Single and multiple n-channel junctionless nanowire transistors (JNTs) are fabricated and experimentally investigated at variable temperatures. Clear current oscillations caused by the quantum-confinement effect are...Single and multiple n-channel junctionless nanowire transistors (JNTs) are fabricated and experimentally investigated at variable temperatures. Clear current oscillations caused by the quantum-confinement effect are observed in the curve of drain current versus gate voltage acquired at low temperatures (10 K-100 K) and variable drain bias voltages (10 mV- 90 mV). Transfer characteristics exhibit current oscillation peaks below flat-band voltage (VFB) at temperatures up to 75 K, which is possibly due to Coulomb-blocking from quantum dots, which are randomly formed by ionized dopants in the just opened n-type one-dimensional (1D) channel of silicon nanowires. However, at higher voltages than VFB, regular current steps are observed in single-channel JNTs, which corresponds to the fully populated subbands in the 1D channel. The subband energy spacing extracted from transconductance peaks accords well with theoretical predication. However, in multiple-channel JNT, only tiny oscillation peaks of the drain current are observed due to the combination of the drain current from multiple channels with quantum-confinement effects.展开更多
A new tutmeling junction can be formed by an insulator layer inserting into a quantum well, and in the quantum well, a quasi-plane tunneling current can be formed by applying a tunneling voltage. If a P-N junction is ...A new tutmeling junction can be formed by an insulator layer inserting into a quantum well, and in the quantum well, a quasi-plane tunneling current can be formed by applying a tunneling voltage. If a P-N junction is grown on the quantum well, the tunneling current can be modulated by a P-N junction-bias voltage. The modulated quasi-plane tunneling current is not only related to the bias voltage, but also to the depth of the quantum well. It is analyzed that the P-N junction-bias voltage how to affect the tunneling current and a method of measuring the depth of the quantum well is presented.展开更多
We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on thesl...We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on theslave-boson mean-field theory,we find that in this system the persistent current(PC)sensitively depends on the parityand size of the AB ring and can be tuned by the spin-flip scattering(R).In the small AB ring,the PC is suppresseddue to the enhancing R weakening the Kondo resonance.On the contrary,in the large AB ring,with R increasing,thepeak of PC firstly moves up to max-peak and then down.Especially,the PC phase shift of π appears suddenly withthe proper value of R,implying the existence of the anomalous Kondo effect in this system.Thus this system may be acandidate for quantum switch.展开更多
A relation of the Josephson current density equation is successfully derived;this is done through a new derivation of the equation of quantum by neglecting kinetic Newtonian term in the energy expression.
A strain-compensated InP-based quantum cascade laser(QCL) structure emitting at 4.6 μm is demonstrated,based on a two-phonon resonant design and grown by solid-source molecular beam epitaxy(MBE).By optimizing the...A strain-compensated InP-based quantum cascade laser(QCL) structure emitting at 4.6 μm is demonstrated,based on a two-phonon resonant design and grown by solid-source molecular beam epitaxy(MBE).By optimizing the growth parameters,a very high quality heterostructure with the lowest threshold current densities ever reported for QCLs was fabricated.Threshold current densities as low as 0.47 kA/cm^2 in pulsed operation and 0.56 kA/cm^2 in continuous-wave(cw) operation at 293 K were achieved for this state-of-the-art QCL.A minimum power consumption of 3.65 W was measured for the QCL,uncooled,with a high-reflectivity(HR) coating on its rear facet.展开更多
基金Project supported by the Science Foundation of Jiangsu Provincial Education 0ffice, China (Grant No 05KJD140035).
文摘On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Helsenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission llne are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission llne, but also dependent on the quantized character of the charge obviously.
基金the National Key Basic Research Development Project (Grant No. 2003CB716204)the International Corporation Project of the Education Department of China (Grant No. 20050360563)+1 种基金the Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu (Grant No. BM2003202) the State Key Laboratory of Solid State Microstructures of Nanjing University
文摘The characteristics of electron transmission through C70 molecule bridge in which two atomic chain leads are connected to long-axis carbon atoms are investigated theoretically by using tight-binding approach based on the Green's function with only one π orbital electron per carbon atom. Electron transmission through C70 molecule from the input to the output terminal is obtained. From the spectrum, the switching feature of the electron transmission through C70 is found, and the oscil-lation property based on the quantized level is explained. The quantum current distributions inside C70 molecule bridge are calculated and simulated by the quan-tum current density theory based on Fisher-Lee formula at the energy point E = -0.2 eV, where the transmission spectrum shows a peak. The maximum and the mini-mum bond quantum currents are presented, and the reason why the currents are distributed nonuniformly is explained by the phase difference of the atomic orbits. The result shows that the currents at each atomic site agree with Kirchhoff quan-tum current conservation law.
基金Supported by the National Natural Science Foundation of China under Grant No 61274101
文摘Heat generated by electric current in a quantum dot device contacting a phonon bath is studied using the non- equilibrium Green function technique. Spin-polarized current is generated owing to the Zeeman splitting of the dot level. The current's strength and the spin polarization are further manipulated by changing the frequency of an applied photon field and the ferromagnetism on the leads. We find that the associated heat by this spin- polarized current emerges even if the bias voltage is smaller than the phonon energy quanta and obvious negative differential of the heat generation develops when the photon frequency exceeds that of the phonon. It is also found that both the strength and the resonant peaks' position of the heat generation can be tuned by changing the value and the arrangement configurations of the magnetic moments of the two leads, and then provides an effective method to generate large spin-polarized current with weak heat. Such a result may be useful in designing low energy consumption spintronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61274101 and 51362031)the Initial Project for High-Level Talents of UESTC,Zhongshan Insitute,China(Grant No.415YKQ02)China Postdoctoral Science Foundation(Grant No.2014M562301)
文摘Spin-polarized current generated by thermal bias across a system composed of a quantum dot (QD) connected to metallic leads is studied in the presence of magnetic and photon fields. The current of a certain spin orientation vanishes when the dot level is aligned to the lead's chemical potential, resulting in a 100% spin-polarized current. The spin-resolved current also changes its sign at the two sides of the zero points. By tuning the system's parameters, spin-up and spin-down currents with equal strength may flow in opposite directions, which induces a pure spin current without the accompany of charge current. With the help of the thermal bias, both the strength and the direction of the spin-polarized current can be manipulated by tuning either the frequency or the intensity of the photon field, which is beyond the reach of the usual electric bias voltage.
文摘Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current js,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current js,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current js,xy is greater than that on the spin current js,yx. The strength of the Rashba spin-orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the. spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20060542002the Hunan Provincial Natural Science Foundation of China under Grant No.06JJ2097the Hunan College of Science and Technology Research Foundation of China under Grant No.07XKYTB001
文摘我们理论上调查在有联合的弱 Dresselhaus 纺纱轨道的一根量电线中的电流连接了到二正常导体的旋转。量电线和售票员被一个难墙的限制潜力描述。用在量电线和旋转电流的一个新定义中的电子波浪功能,我们计算了线性旋转电流密度 j <SUB 的元素> s , x i </SUB><SUP > T </SUP>和 j <SUB > s , yi </SUB><SUP > T </SUP>( i = x , y ,z)。我们发现元素 j <SUP > T </SUP><SUB > s , x x </SUB>和 j <SUP > T </SUP><SUB > s , yy </SUB>有反对称的关系和元素 j <SUP > T </SUP><SUB > s , yz </SUB>作为 j <SUB 有一样的数量水平> s , x x </SUB><SUP > T </SUP>和 j <SUB > s , yy </SUB><SUP > T </SUP>。我们也发现一张网线性旋转电流密度,它在量电线的中心有山峰。线性旋转电流能导致的网一个线性电场,它可以暗示旋转电流的一个方法察觉。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874020 and 11174042)the National Basic Research Program of China (Grants No. 2011CB922204)+1 种基金the CAEP,China (Grant No. 2011B0102024)the SRF for ROCS,SEM,China
文摘We analyze the transport through asymmetric double quantum dots with an inhomogeneous Zeeman splitting in the presence of crossed dc and ac magnetic fields. A strong spin-polarized current can be obtained by changing the dc magnetic field. It is mainly due to the resonant tunnelling. But for the ferromagnetic right electrode, the electron spin resonance also plays an important role in transport. We show that the double quantum dots with three-level mixing under crossed dc and ac magnetic fields can act not only as a bipolar spin filter but also as a spin inverter under suitable conditions.
基金supported by the Special Funds for the Development of National Major Scientific Instruments and Equipment,China(Grant No.2012YQ160007)the National Natural Science Foundation of China(Grant No.51277185)
文摘In this paper,the frequency-locking and threshold current-lowering effects of a quantum cascade laser are studied and achieved.Combined with cavity-enhanced absorption spectroscopy,the noninvasive detection of H_2 with a prepared concentration of 500 ppm in multiple dissolved gases is performed and evaluated.The high frequency selectivity of 0.0051 cm^-1 at an acquisition time of 1 s allows the sensitive detection of the(1-0) S(l) band of H_2 with a high accuracy of(96.53±0.29)%and shows that the detection limit to an absorption line of 4712.9046 cm^-1 is approximately(17.26±0.63) ppm at an atmospheric pressure and a temperature of 20 ℃.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574042) and the Scientific Research Fund of Hunan Provincial Education Department (Grant No 04A031).
文摘The spin current in a parabolically confined semiconductor hcterojunction quantum wire with Drcsselhaus spinorbit coupling is theoretically studied by using the perturbation method. The formulae of the elements for linear and angular spin current densities are derived by using the recent definition for spin current based on spin continuity equation. It is found that the spin current in this Dresselhaus spin-orbit coupling quantum wire is antisymmetrical, which is different from that in Rashba model due to the difference in symmetry between these two models. Some numerical examples for the result are also demonstrated and discussed.
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB632801 and 2013CB632803the National Natural Science Foundation of China under Grant Nos 61435014,61306058 and 61274094the Beijing Natural Science Foundation under Grant No 4144086
文摘We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.
基金Project supported by the National Natural Science Foundation of China (Grant No 10447116) and the Science Foundation for Post Doctorate of China (Grant No 2005038316).Acknowledgment We would like to thank Professor Z. Pácz for helpful discussion.
文摘The ground-state entanglement associated with a three-spin transverse Ising model is studied. By introducing an energy current into the system, a quantum phase transition to energy-current phase may be presented with the variation of external magnetic field; and the ground-state entanglement varies suddenly at the critical point of quantum phase transition. In our model, the introduction of energy current makes the entanglement between any two qubits become maximally robust.
基金Project supported partly by the National Basic Research Program of China(Grant No.2010CB934104)the National Natural Science Foundation of China(Grant Nos.61376069 and 61327813)
文摘Single and multiple n-channel junctionless nanowire transistors (JNTs) are fabricated and experimentally investigated at variable temperatures. Clear current oscillations caused by the quantum-confinement effect are observed in the curve of drain current versus gate voltage acquired at low temperatures (10 K-100 K) and variable drain bias voltages (10 mV- 90 mV). Transfer characteristics exhibit current oscillation peaks below flat-band voltage (VFB) at temperatures up to 75 K, which is possibly due to Coulomb-blocking from quantum dots, which are randomly formed by ionized dopants in the just opened n-type one-dimensional (1D) channel of silicon nanowires. However, at higher voltages than VFB, regular current steps are observed in single-channel JNTs, which corresponds to the fully populated subbands in the 1D channel. The subband energy spacing extracted from transconductance peaks accords well with theoretical predication. However, in multiple-channel JNT, only tiny oscillation peaks of the drain current are observed due to the combination of the drain current from multiple channels with quantum-confinement effects.
文摘A new tutmeling junction can be formed by an insulator layer inserting into a quantum well, and in the quantum well, a quasi-plane tunneling current can be formed by applying a tunneling voltage. If a P-N junction is grown on the quantum well, the tunneling current can be modulated by a P-N junction-bias voltage. The modulated quasi-plane tunneling current is not only related to the bias voltage, but also to the depth of the quantum well. It is analyzed that the P-N junction-bias voltage how to affect the tunneling current and a method of measuring the depth of the quantum well is presented.
基金Supported by Scientific Research Fund of Hunan Provincial Education Department under Grant No.09B079
文摘We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on theslave-boson mean-field theory,we find that in this system the persistent current(PC)sensitively depends on the parityand size of the AB ring and can be tuned by the spin-flip scattering(R).In the small AB ring,the PC is suppresseddue to the enhancing R weakening the Kondo resonance.On the contrary,in the large AB ring,with R increasing,thepeak of PC firstly moves up to max-peak and then down.Especially,the PC phase shift of π appears suddenly withthe proper value of R,implying the existence of the anomalous Kondo effect in this system.Thus this system may be acandidate for quantum switch.
文摘A relation of the Josephson current density equation is successfully derived;this is done through a new derivation of the equation of quantum by neglecting kinetic Newtonian term in the energy expression.
基金supported by the National Basic Research Program of China(Grant Nos.2013CB632801 and 2013CB632803)the National Natural Science Foundation of China(Grant Nos.61306058,61274094,and 61435014)the Beijing Natural Science Foundation(Grant No.4144086)
文摘A strain-compensated InP-based quantum cascade laser(QCL) structure emitting at 4.6 μm is demonstrated,based on a two-phonon resonant design and grown by solid-source molecular beam epitaxy(MBE).By optimizing the growth parameters,a very high quality heterostructure with the lowest threshold current densities ever reported for QCLs was fabricated.Threshold current densities as low as 0.47 kA/cm^2 in pulsed operation and 0.56 kA/cm^2 in continuous-wave(cw) operation at 293 K were achieved for this state-of-the-art QCL.A minimum power consumption of 3.65 W was measured for the QCL,uncooled,with a high-reflectivity(HR) coating on its rear facet.