A novel unselective regrowth buried heterostructure long-wavelength superluminescent diode （SLD） with a graded composition bulk InGaAs active region is developed by metalorganic vapor phase epitaxy （MOVPE）. At a 1...A novel unselective regrowth buried heterostructure long-wavelength superluminescent diode （SLD） with a graded composition bulk InGaAs active region is developed by metalorganic vapor phase epitaxy （MOVPE）. At a 150mA injection current, the full width at half maximum of the emission spectrum of the SLD is about 72nm, ranging from 1602 to 1674nm. The emission spectrum is smooth and flat. The ripple of the spectrum is less than 0.3dB at any wavelength from 1550 to 1700nm. An output power of 4.3mW is obtained at a 200mA injection current under continuous-wave operation at room temperature. This device is suitable for the applications of light sources for gas detectors and L-band optical fiber communications.展开更多
With the aim of achieving high coupling power of RWG SLDs into SMFs,the structure dependences of the output power and the near field pattern are investigated. The thicknesses of the layers between the active region an...With the aim of achieving high coupling power of RWG SLDs into SMFs,the structure dependences of the output power and the near field pattern are investigated. The thicknesses of the layers between the active region and the ridge waveguide are optimized by taking into account the injected carrier distribution and local material gain in the SLD cross section.展开更多
With a chirped InAs/GaAs SML-QD （quantum dot） structure serving as the active region, the superluminescent diodes emitting at wavelength of around 970nm are fabricated. By using an active multimode interferometer co...With a chirped InAs/GaAs SML-QD （quantum dot） structure serving as the active region, the superluminescent diodes emitting at wavelength of around 970nm are fabricated. By using an active multimode interferometer configuration, these devices exhibit high continue-wave output powers from the narrow ridge waveguides. At continue-wave injection current of 800mA, an output power of 18.5mW, and the single Gaussian-like emission spectrum centered at 972nm with a full width at half maximum of 18nm are obtained.展开更多
This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAl- GaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full widt...This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAl- GaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full width at half maximum of 37 nm and an output power of 18 mW. By incorporating an Al composition into the quan- tum dot active region, short-wavelength superluminescent diode devices can be obtained. An intersection was found for the light power-injection current curves measured from the straight-waveguide facet and the bent-waveguide facet, respectively. The result is attributed to the conjunct effects of the gain and the additional loss of the bent waveguide. A numerical simulation is performed to verify the qualitative explanation. It is shown that bent waveguide loss is an important factor that affects the output power of J-shaped superluminescent diode devices.展开更多
We report on the fabrication and characterization of InAs/GaAs chirped multilayer quantum-dot superluminescent diodes(CMQD-SLDs)with and without direct Si doping in QDs.It was found that both the output power and the ...We report on the fabrication and characterization of InAs/GaAs chirped multilayer quantum-dot superluminescent diodes(CMQD-SLDs)with and without direct Si doping in QDs.It was found that both the output power and the spectral width of the CMQD-SLDs were significantly enhanced by direct Si doping in the QDs.The output power and spectral width have been increased by approximately 18.3%and 40%,respectively.Moreover,we shortened the cavity length of the doped CMQD-SLD and obtained a spectral width of 106 nm.In addition,the maximum output power and spectral width of the CMQD-SLD doped directly with Si can be further increased to 16.6 mW and 114 nm,respectively,through anti-reflection coating and device packaging.The device exhibited the smallest spectral dip of 0.2 dB when the spectrum was widest.The improved performances of the doped CMQD-SLD can be attributed to the direct doping of Si in the QDs,optimization of device structure and device packaging.展开更多
Visible-light communication(VLC)stands as a promising component of the future communication network by providing high-capacity,low-latency,and high-security wireless communication.Superluminescent diode(SLD)is propose...Visible-light communication(VLC)stands as a promising component of the future communication network by providing high-capacity,low-latency,and high-security wireless communication.Superluminescent diode(SLD)is proposed as a new light emitter in the VLC system due to its properties of droop-free emission,high optical power density,and low speckle-noise.In this paper,we analyze a VLC system based on SLD,demonstrating effective implementation of carrierless amplitude and phase modulation(CAP).We create a low-complexity memory-polynomial-aided neural network(MPANN)to replace the traditional finite impulse response(FIR)post-equalization filters of CAP,leading to significant mitigation of the linear and nonlinear distortion of the VLC channel.The MPANN shows a gain in Q factor of up to 2.7 dB higher than other equalizers,and more than four times lower complexity than a standard deep neural network(DNN),hence,the proposed MPANN opens a pathway for the next generation of robust and efficient neural network equalizers in VLC.We experimentally demonstrate a proof-of-concept 2.95-Gbit/s transmission using MPANN-aided CAP with 16-quadrature amplitude modulation(16-QAM)through a 30-cm channel based on the 442-nm blue SLD emitter.展开更多
According to the InAs/GaAs submonolayer quantum dot active region, we demonstrate a bent-waveguide superluminescent diode emitting at a wavelength of around 970 nm. At a pulsed injection current of 0.5 A, the device e...According to the InAs/GaAs submonolayer quantum dot active region, we demonstrate a bent-waveguide superluminescent diode emitting at a wavelength of around 970 nm. At a pulsed injection current of 0.5 A, the device exhibits an output power of 24 mW and an emission spectrum centred at 971 nm with a full width at half maximum of 16 nm.展开更多
The design,fabrication and performance of 1.3μm superluminescent diodes are reported.A InP window structure and a passive absorber waveguide in different plane are applied to suppress lasing oscillation.A buried cres...The design,fabrication and performance of 1.3μm superluminescent diodes are reported.A InP window structure and a passive absorber waveguide in different plane are applied to suppress lasing oscillation.A buried crescent structure similar to a laser diode is introduced to achieve high output power.The output power of about 70O μW is coupled into a single-mode fiber at 150 mA and 25℃.Spectrum width is more than 30 nm.The devices operate in superluminescent state in the range from 0℃ to 60℃.展开更多
We present a stochastic procedure to investigate the correlation spectra of quantum dot superluminescent diodes. The classical electric field of a diode is formed by a polychromatic superposition of many independent s...We present a stochastic procedure to investigate the correlation spectra of quantum dot superluminescent diodes. The classical electric field of a diode is formed by a polychromatic superposition of many independent stochastic oscillators. Assuming fields with individual carrier frequencies, Lorentzian linewidths and amplitudes we can form any relevant experimental spectrum using a least square fit. This is illustrated for Gaussian and Lorentzian spectra, Voigt profiles and box shapes. Eventually, the procedure is applied to an experimental spectrum of a quantum dot superluminescent diode which determines the first- and second-order temporal correlation functions of the emission. We find good agreement with the experimental data and a quantized treatment. Thus, a superposition of independent stochastic oscillators represents the first- and second-order correlation properties of broadband light emitted by quantum dot superluminescent diodes.展开更多
We report a new quantum dot superluminescent diode with a new device structure. In this device, a multi- mode-interferometer configuration and a J-bend structure were monolithically integrated. Owing to the multi-mode...We report a new quantum dot superluminescent diode with a new device structure. In this device, a multi- mode-interferometer configuration and a J-bend structure were monolithically integrated. Owing to the multi-mode- interferometer structure, the superluminescent diode exhibits 60% increase in output power and 43% reduction in the differential resistance compared with the uniform waveguide width superluminescent diode fabricated from the same wafer. Our device produces an emission spectrum as wide as 103.7 nm with an output power of 2.5 mW at 600 mA continue-wave injection current. This broadband emission spectrum makes the axial resolution of the optical coherence tomography system employing the superluminescent diode to 6 μm in theory, which is high enough for most tissue imaging.展开更多
The optical loss in the bent region is one of the key features for bent-waveguide superluminescent diodes that affects the device performance greatly under some conditions. For the purpose of device fabrication and op...The optical loss in the bent region is one of the key features for bent-waveguide superluminescent diodes that affects the device performance greatly under some conditions. For the purpose of device fabrication and optimization, it will be helpful if this bend loss can be estimated. In this letter, we have derived an analytical formula which can be used to get the bend-loss coefficient by fitting the P-I curves of the devices. It is proved that the formula is successful in estimating the loss coefficients from the P-I curves simulated from a complicated quantum-dot device model. We expect this method could also be valid in estimating bend losses of actual devices.展开更多
We present a novel superluminescent diode （SLD） with high optical performances for hardened neutron irradiation. The degradation of the light output from the SLDs is caused by a reduction of the minority carrier lif...We present a novel superluminescent diode （SLD） with high optical performances for hardened neutron irradiation. The degradation of the light output from the SLDs is caused by a reduction of the minority carrier lifetime resulting from displacement damage after high-energy neutron irradiation. The SLDs with a higher pre- irradiation light output will be less sensitive to radiation. We have selected an InGaAsP/InP multi-quantum well （MQW） as the active region structure for its performance, its high optical gain and minute active region. Graded- index separate-confinement-heterostructure （GRIN-SCH） has been applied for the waveguide structure. A specific absorbing region and anti-reflective coatings have been designed and optimized. Moreover, the radiation test results indicate that the SLD with an InGaAsP/InP MQW structure has better neutron hardening ability than the SLD with DH structures after a 6×10^13-1×10^14 n/cm^2 1 MeV neutron irradiation.展开更多
We demonstrate InGaN violet light-emitting superluminescent diodes with large spectral width suitable for applications in optical coherence spectroscopy.This was achieved using the concept of nonlinear indium content ...We demonstrate InGaN violet light-emitting superluminescent diodes with large spectral width suitable for applications in optical coherence spectroscopy.This was achieved using the concept of nonlinear indium content profile along the superluminescent diode waveguide.A specially designed 3D substrate surface shape leads to a step-like indium content profile,with the indium concentration in the InGaN/GaN quantum wells ranging approximately between 6% and 10%.Thanks to this approach,we were able to increase the width of the spectrum in processed devices from 2.6 nm(reference diode)to 15.5 nm.展开更多
Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defe...Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.展开更多
Superluminescence diode(SLD) modules with wide spectrum characteristics are required in fiber gyroscopes. A 1.3 μm butterfly packaged superluminescence diode with the spectrum width over 30 nm is reported and recent ...Superluminescence diode(SLD) modules with wide spectrum characteristics are required in fiber gyroscopes. A 1.3 μm butterfly packaged superluminescence diode with the spectrum width over 30 nm is reported and recent advances in process of SLD is described in the paper. The SLD modules have been applied to fiber gyroscopes.展开更多
Using non-identical quantum wells as the active material, a new distributed-feedback laser is fabricated with period varied Bragg grating. The full width at half maximum of I 15 nm is observed in the amplified spontan...Using non-identical quantum wells as the active material, a new distributed-feedback laser is fabricated with period varied Bragg grating. The full width at half maximum of I 15 nm is observed in the amplified spontaneous emission spectrum of this material, which is flatter and wider than that of the identical quantum wells. Two wavelengths of 1.51 μm and 1.53 μm are realized under different work conditions. The side-mode suppression ratios of both wavelengths reach 40 dB. This device can be used as the light source of coarse wavelength division multiplexer communication systems.展开更多
We report the effect of the GaAs spacer layer thickness on the photoluminescence （PL） spectral bandwidth of InAs/GaAs self-assembled quantum dots （QDs）. A PL spectral bandwidth of 158 nm is achieved with a five-la...We report the effect of the GaAs spacer layer thickness on the photoluminescence （PL） spectral bandwidth of InAs/GaAs self-assembled quantum dots （QDs）. A PL spectral bandwidth of 158 nm is achieved with a five-layer stack of InAs QDs which has a 11-nm thick GaAs spacer layer. We investigate the optical and the structurM properties of the multilayer-stacked InAs/GaAs QDs with different GaAs spacer layer thicknesses. The results show that the spacer thickness is a key parameter affecting the multi-stacked InAs/GaAs QDs for wide-spectrum emission.展开更多
文摘A novel unselective regrowth buried heterostructure long-wavelength superluminescent diode （SLD） with a graded composition bulk InGaAs active region is developed by metalorganic vapor phase epitaxy （MOVPE）. At a 150mA injection current, the full width at half maximum of the emission spectrum of the SLD is about 72nm, ranging from 1602 to 1674nm. The emission spectrum is smooth and flat. The ripple of the spectrum is less than 0.3dB at any wavelength from 1550 to 1700nm. An output power of 4.3mW is obtained at a 200mA injection current under continuous-wave operation at room temperature. This device is suitable for the applications of light sources for gas detectors and L-band optical fiber communications.
文摘With the aim of achieving high coupling power of RWG SLDs into SMFs,the structure dependences of the output power and the near field pattern are investigated. The thicknesses of the layers between the active region and the ridge waveguide are optimized by taking into account the injected carrier distribution and local material gain in the SLD cross section.
基金Project supported by the National Basic Research Program of China (Grant No. 2006CB604904)the National Natural Science Foundation of China (Grant Nos. 60976057, 61274072, and 60876086)
文摘With a chirped InAs/GaAs SML-QD （quantum dot） structure serving as the active region, the superluminescent diodes emitting at wavelength of around 970nm are fabricated. By using an active multimode interferometer configuration, these devices exhibit high continue-wave output powers from the narrow ridge waveguides. At continue-wave injection current of 800mA, an output power of 18.5mW, and the single Gaussian-like emission spectrum centered at 972nm with a full width at half maximum of 18nm are obtained.
基金supported by the National Basic Research Program of China (Grant No. 2006CB604904)the National Natural Science Foundation of China (Grant Nos. 60876086, 60976057, and 60776037)
文摘This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAl- GaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full width at half maximum of 37 nm and an output power of 18 mW. By incorporating an Al composition into the quan- tum dot active region, short-wavelength superluminescent diode devices can be obtained. An intersection was found for the light power-injection current curves measured from the straight-waveguide facet and the bent-waveguide facet, respectively. The result is attributed to the conjunct effects of the gain and the additional loss of the bent waveguide. A numerical simulation is performed to verify the qualitative explanation. It is shown that bent waveguide loss is an important factor that affects the output power of J-shaped superluminescent diode devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62035012,62074143,and 62004191)Zhejiang Lab (Grant No.2020LC0AD02)
文摘We report on the fabrication and characterization of InAs/GaAs chirped multilayer quantum-dot superluminescent diodes(CMQD-SLDs)with and without direct Si doping in QDs.It was found that both the output power and the spectral width of the CMQD-SLDs were significantly enhanced by direct Si doping in the QDs.The output power and spectral width have been increased by approximately 18.3%and 40%,respectively.Moreover,we shortened the cavity length of the doped CMQD-SLD and obtained a spectral width of 106 nm.In addition,the maximum output power and spectral width of the CMQD-SLD doped directly with Si can be further increased to 16.6 mW and 114 nm,respectively,through anti-reflection coating and device packaging.The device exhibited the smallest spectral dip of 0.2 dB when the spectrum was widest.The improved performances of the doped CMQD-SLD can be attributed to the direct doping of Si in the QDs,optimization of device structure and device packaging.
基金the National Key Research,Development Program of China(2017YFB0403603)the NSFC project(No.61925104).JAHL,YM,TKN and BSO gratefully acknowledge the financial support from King Abdullah University of Science and Technology(KAUST)through BAS/1/1614-01-01,REP/1/2878-01-01,GEN/1/6607-01-01,and KCR/1/2081-01-01the King Abdullah University of Science and Technology(KAUST)Office of Sponsored Research(OSR)under Award No.OSR-CRG2017-3417.JAHL further acknowledge access to the KAUST Nanofabrication Core Lab for the fabrication of devices.
文摘Visible-light communication(VLC)stands as a promising component of the future communication network by providing high-capacity,low-latency,and high-security wireless communication.Superluminescent diode(SLD)is proposed as a new light emitter in the VLC system due to its properties of droop-free emission,high optical power density,and low speckle-noise.In this paper,we analyze a VLC system based on SLD,demonstrating effective implementation of carrierless amplitude and phase modulation(CAP).We create a low-complexity memory-polynomial-aided neural network(MPANN)to replace the traditional finite impulse response(FIR)post-equalization filters of CAP,leading to significant mitigation of the linear and nonlinear distortion of the VLC channel.The MPANN shows a gain in Q factor of up to 2.7 dB higher than other equalizers,and more than four times lower complexity than a standard deep neural network(DNN),hence,the proposed MPANN opens a pathway for the next generation of robust and efficient neural network equalizers in VLC.We experimentally demonstrate a proof-of-concept 2.95-Gbit/s transmission using MPANN-aided CAP with 16-quadrature amplitude modulation(16-QAM)through a 30-cm channel based on the 442-nm blue SLD emitter.
基金supported by the National Basic Research Program of China (Grant No.2006CB604904)the National Natural Science Foundation of China (Grant Nos.60876086,60976057,and 60776037)
文摘According to the InAs/GaAs submonolayer quantum dot active region, we demonstrate a bent-waveguide superluminescent diode emitting at a wavelength of around 970 nm. At a pulsed injection current of 0.5 A, the device exhibits an output power of 24 mW and an emission spectrum centred at 971 nm with a full width at half maximum of 16 nm.
文摘The design,fabrication and performance of 1.3μm superluminescent diodes are reported.A InP window structure and a passive absorber waveguide in different plane are applied to suppress lasing oscillation.A buried crescent structure similar to a laser diode is introduced to achieve high output power.The output power of about 70O μW is coupled into a single-mode fiber at 150 mA and 25℃.Spectrum width is more than 30 nm.The devices operate in superluminescent state in the range from 0℃ to 60℃.
文摘We present a stochastic procedure to investigate the correlation spectra of quantum dot superluminescent diodes. The classical electric field of a diode is formed by a polychromatic superposition of many independent stochastic oscillators. Assuming fields with individual carrier frequencies, Lorentzian linewidths and amplitudes we can form any relevant experimental spectrum using a least square fit. This is illustrated for Gaussian and Lorentzian spectra, Voigt profiles and box shapes. Eventually, the procedure is applied to an experimental spectrum of a quantum dot superluminescent diode which determines the first- and second-order temporal correlation functions of the emission. We find good agreement with the experimental data and a quantized treatment. Thus, a superposition of independent stochastic oscillators represents the first- and second-order correlation properties of broadband light emitted by quantum dot superluminescent diodes.
基金supported by the National Natural Science Foundation of China(No.61274072)the National High Technology Research and Development Program of China(No.2013AA014201)
文摘We report a new quantum dot superluminescent diode with a new device structure. In this device, a multi- mode-interferometer configuration and a J-bend structure were monolithically integrated. Owing to the multi-mode- interferometer structure, the superluminescent diode exhibits 60% increase in output power and 43% reduction in the differential resistance compared with the uniform waveguide width superluminescent diode fabricated from the same wafer. Our device produces an emission spectrum as wide as 103.7 nm with an output power of 2.5 mW at 600 mA continue-wave injection current. This broadband emission spectrum makes the axial resolution of the optical coherence tomography system employing the superluminescent diode to 6 μm in theory, which is high enough for most tissue imaging.
基金Project supported by the National Natural Science Foundation of China(Nos.61274072,60976057)
文摘The optical loss in the bent region is one of the key features for bent-waveguide superluminescent diodes that affects the device performance greatly under some conditions. For the purpose of device fabrication and optimization, it will be helpful if this bend loss can be estimated. In this letter, we have derived an analytical formula which can be used to get the bend-loss coefficient by fitting the P-I curves of the devices. It is proved that the formula is successful in estimating the loss coefficients from the P-I curves simulated from a complicated quantum-dot device model. We expect this method could also be valid in estimating bend losses of actual devices.
文摘We present a novel superluminescent diode （SLD） with high optical performances for hardened neutron irradiation. The degradation of the light output from the SLDs is caused by a reduction of the minority carrier lifetime resulting from displacement damage after high-energy neutron irradiation. The SLDs with a higher pre- irradiation light output will be less sensitive to radiation. We have selected an InGaAsP/InP multi-quantum well （MQW） as the active region structure for its performance, its high optical gain and minute active region. Graded- index separate-confinement-heterostructure （GRIN-SCH） has been applied for the waveguide structure. A specific absorbing region and anti-reflective coatings have been designed and optimized. Moreover, the radiation test results indicate that the SLD with an InGaAsP/InP MQW structure has better neutron hardening ability than the SLD with DH structures after a 6×10^13-1×10^14 n/cm^2 1 MeV neutron irradiation.
基金Narodowe Centrum Nauki(NCN)(2014/15/B/ST3/04252)Narodowe Centrum Badan'i Rozwoju(NCBR)(1/POLBER-1/2014)
文摘We demonstrate InGaN violet light-emitting superluminescent diodes with large spectral width suitable for applications in optical coherence spectroscopy.This was achieved using the concept of nonlinear indium content profile along the superluminescent diode waveguide.A specially designed 3D substrate surface shape leads to a step-like indium content profile,with the indium concentration in the InGaN/GaN quantum wells ranging approximately between 6% and 10%.Thanks to this approach,we were able to increase the width of the spectrum in processed devices from 2.6 nm(reference diode)to 15.5 nm.
基金supported by the Key Research and Development Plan of Ministry of Science and Technology(No.2016YFB0402303)the National Natural Science Foundation of China(No.61575222)+1 种基金the open project of the State Key Laboratory of Luminescence and ApplicationsChina Postdoctoral Science Foundation(No.2017M621858)
文摘Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.
文摘Superluminescence diode(SLD) modules with wide spectrum characteristics are required in fiber gyroscopes. A 1.3 μm butterfly packaged superluminescence diode with the spectrum width over 30 nm is reported and recent advances in process of SLD is described in the paper. The SLD modules have been applied to fiber gyroscopes.
基金Supported by the National Basic Research and Development Programme of China Grant No G20000683-1, the National Natural Science Foundation of China under Grant No 90401025, and the National Hi-Tech Researcn and Development Programme of China under Grant No 2002AA312150.
文摘Using non-identical quantum wells as the active material, a new distributed-feedback laser is fabricated with period varied Bragg grating. The full width at half maximum of I 15 nm is observed in the amplified spontaneous emission spectrum of this material, which is flatter and wider than that of the identical quantum wells. Two wavelengths of 1.51 μm and 1.53 μm are realized under different work conditions. The side-mode suppression ratios of both wavelengths reach 40 dB. This device can be used as the light source of coarse wavelength division multiplexer communication systems.
基金Project supported by the National Basic Research Program of China (Grant No. 2006CB604904)the National Natural Science Foundation of China (Grant Nos. 60976057,61274072,and 60776037)
文摘We report the effect of the GaAs spacer layer thickness on the photoluminescence （PL） spectral bandwidth of InAs/GaAs self-assembled quantum dots （QDs）. A PL spectral bandwidth of 158 nm is achieved with a five-layer stack of InAs QDs which has a 11-nm thick GaAs spacer layer. We investigate the optical and the structurM properties of the multilayer-stacked InAs/GaAs QDs with different GaAs spacer layer thicknesses. The results show that the spacer thickness is a key parameter affecting the multi-stacked InAs/GaAs QDs for wide-spectrum emission.
