Semiconductor broadband light emitters have emerged as ideal and vital light sources for a range of biomedical sensing/imaging applications,especially for optical coherence tomography systems.Although near-infrared br...Semiconductor broadband light emitters have emerged as ideal and vital light sources for a range of biomedical sensing/imaging applications,especially for optical coherence tomography systems.Although near-infrared broadband light emitters have found increasingly wide utilization in these imaging applications,the requirement to simultaneously achieve both a high spectral bandwidth and output power is still challenging for such devices.Owing to the relatively weak amplified spontaneous emission,as a consequence of the very short non-radiative carrier lifetime of the inter-subband transitions in quantum cascade structures,it is even more challenging to obtain desirable mid-infrared broadband light emitters.There have been great efforts in the past 20 years to pursue high-efficiency broadband optical gain and very low reflectivity in waveguide structures,which are two key factors determining the performance of broadband light emitters.Here we describe the realization of a high continuous wave light power of 420 mW and broadband width of 4130 nm with near-infrared broadband light emitters and the first mid-infrared broadband light emitters operating under continuous wave mode at room temperature by employing a modulation p-doped InGaAs/GaAs quantum dot active region with a‘J’-shape ridge waveguide structure and a quantum cascade active region with a dual-end analogous monolithic integrated tapered waveguide structure,respectively.This work is of great importance to improve the performance of existing near-infrared optical coherence tomography systems and describes a major advance toward reliable and costeffective mid-infrared imaging and sensing systems,which do not presently exist due to the lack of appropriate low-coherence mid-infrared semiconductor broadband light sources.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
Intense heat waves pose a serious threat to public health and well-being,especially in outdoor spaces.Outdoor high-temperature environments without air conditioners are major challenges for humanity.However,an achieva...Intense heat waves pose a serious threat to public health and well-being,especially in outdoor spaces.Outdoor high-temperature environments without air conditioners are major challenges for humanity.However,an achievable approach that can provide outdoor cooling without consuming any energy is lacking.Hence,this work presents a novel hierarchical fabric emitter(HFET)used for sunshade sheds to provide radiative outdoor cooling for humanity,the HFET is composed of polyethylene/silicon dioxide/silicon nitride film,melt-blown polypropylene film,and polydimethylsiloxane film from top to bottom.In addition to reflecting 94%solar irradiance by its top surface,the HFET shows selective emission(0.82 in the atmospheric window and 0.38 outside the atmospheric window)on its top surface to outer space and broadband absorption(0.80 in the longwave infrared band)on its bottom surface from the inside.This bidirectional asymmetric emission enables the simulated skin to avoid overheating by 2-11°C relative to the reverse HFET and bare cases under direct sunlight.Due to its excellent cooling capability,the HFET will be one of the most considerable solutions for outdoor cooling in hot sum-mer environments.展开更多
We report a complementary metal oxide semiconductor(CMOS)compatible metamaterial-based spectrally selective absorber/emitter(MBSSAE)for infrared(IR)stealth,which has the low absorption/emissivity in the IR atmospheric...We report a complementary metal oxide semiconductor(CMOS)compatible metamaterial-based spectrally selective absorber/emitter(MBSSAE)for infrared(IR)stealth,which has the low absorption/emissivity in the IR atmospheric transmission window(3μm-5μm,8μm-14μm)and ultra-high and broadband absorption/emissivity in the IR non-atmospheric window(5μm-8μm).We propose a novel method for the broadband absorption/emissivity in 5μm-8μm with incorporation of an epsilon-near-zero(ENZ)material between the top patterned aluminum(Al)disks layer and the silicon oxide(SiO_(2))spacer layer.With an appropriate design,the peaks in the IR atmospheric transmission window can be suppressed while the peak intensity in the non-atmospheric window remains high.The optimized MBSSAE has an average absorption/emissivity less than 10%in 8μm-14μm and less than 6%in 3μm-5μm.And the average absorption/emissivity in 5μm-8μm is approximately over 64%.This proposed scheme may introduce the opportunities for the large-area and low-cost infrared stealth coating,as well as for the radiative cooling,spectral selective thermal detector,optical sensor,and thermophotovoltaic applications.展开更多
Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-stat...Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-states of Ar(q】8)were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter.To investigate possible enhancements with broadband microwave radiation,a"white"Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of～200MHz.The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region.However,the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned off the flat-B region.展开更多
基金the financial support from the Natural Science Foundation of China(61575215)the National Research Projects of China(2013CB632800)the Thousand Youth Talents Plan and the Key Research and Development Plan of Ministry of Science and Technology(2016YFB0402303)。
文摘Semiconductor broadband light emitters have emerged as ideal and vital light sources for a range of biomedical sensing/imaging applications,especially for optical coherence tomography systems.Although near-infrared broadband light emitters have found increasingly wide utilization in these imaging applications,the requirement to simultaneously achieve both a high spectral bandwidth and output power is still challenging for such devices.Owing to the relatively weak amplified spontaneous emission,as a consequence of the very short non-radiative carrier lifetime of the inter-subband transitions in quantum cascade structures,it is even more challenging to obtain desirable mid-infrared broadband light emitters.There have been great efforts in the past 20 years to pursue high-efficiency broadband optical gain and very low reflectivity in waveguide structures,which are two key factors determining the performance of broadband light emitters.Here we describe the realization of a high continuous wave light power of 420 mW and broadband width of 4130 nm with near-infrared broadband light emitters and the first mid-infrared broadband light emitters operating under continuous wave mode at room temperature by employing a modulation p-doped InGaAs/GaAs quantum dot active region with a‘J’-shape ridge waveguide structure and a quantum cascade active region with a dual-end analogous monolithic integrated tapered waveguide structure,respectively.This work is of great importance to improve the performance of existing near-infrared optical coherence tomography systems and describes a major advance toward reliable and costeffective mid-infrared imaging and sensing systems,which do not presently exist due to the lack of appropriate low-coherence mid-infrared semiconductor broadband light sources.
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Priority Academic Program Development of Jiangsu Higher Education Institution(PAPD)National Natural Science Foundation of China(52204222)National Students’Platform for Innovation and Entrepreneurship Training Program(202210291001Z).
文摘Intense heat waves pose a serious threat to public health and well-being,especially in outdoor spaces.Outdoor high-temperature environments without air conditioners are major challenges for humanity.However,an achievable approach that can provide outdoor cooling without consuming any energy is lacking.Hence,this work presents a novel hierarchical fabric emitter(HFET)used for sunshade sheds to provide radiative outdoor cooling for humanity,the HFET is composed of polyethylene/silicon dioxide/silicon nitride film,melt-blown polypropylene film,and polydimethylsiloxane film from top to bottom.In addition to reflecting 94%solar irradiance by its top surface,the HFET shows selective emission(0.82 in the atmospheric window and 0.38 outside the atmospheric window)on its top surface to outer space and broadband absorption(0.80 in the longwave infrared band)on its bottom surface from the inside.This bidirectional asymmetric emission enables the simulated skin to avoid overheating by 2-11°C relative to the reverse HFET and bare cases under direct sunlight.Due to its excellent cooling capability,the HFET will be one of the most considerable solutions for outdoor cooling in hot sum-mer environments.
基金supported by the National Natural Science Foundation of China(Grant Nos.61734002,61435010,61177035,and 61421002).
文摘We report a complementary metal oxide semiconductor(CMOS)compatible metamaterial-based spectrally selective absorber/emitter(MBSSAE)for infrared(IR)stealth,which has the low absorption/emissivity in the IR atmospheric transmission window(3μm-5μm,8μm-14μm)and ultra-high and broadband absorption/emissivity in the IR non-atmospheric window(5μm-8μm).We propose a novel method for the broadband absorption/emissivity in 5μm-8μm with incorporation of an epsilon-near-zero(ENZ)material between the top patterned aluminum(Al)disks layer and the silicon oxide(SiO_(2))spacer layer.With an appropriate design,the peaks in the IR atmospheric transmission window can be suppressed while the peak intensity in the non-atmospheric window remains high.The optimized MBSSAE has an average absorption/emissivity less than 10%in 8μm-14μm and less than 6%in 3μm-5μm.And the average absorption/emissivity in 5μm-8μm is approximately over 64%.This proposed scheme may introduce the opportunities for the large-area and low-cost infrared stealth coating,as well as for the radiative cooling,spectral selective thermal detector,optical sensor,and thermophotovoltaic applications.
基金Supported by the U.S.Department of Energy under contract DE-AC05-00OR22725 with UT-Battelle,LLC
文摘Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-states of Ar(q】8)were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter.To investigate possible enhancements with broadband microwave radiation,a"white"Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of～200MHz.The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region.However,the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned off the flat-B region.
