A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture.With the advent of high-resolution ima...A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture.With the advent of high-resolution image sensors and color filter technologies,multispectral imagers in the visible wavelengths have become popular with increasing commercial viability in the last decade.However,multispectral imaging in longwave infrared(LWIR,8-14μm)is still an emerging area due to the limited availability of optical materials,filter technologies,and high-resolution sensors.Images from LWIR multispectral cameras can capture emission spectra of objects to extract additional information that a human eye fails to capture and thus have important applications in precision agriculture,forestry,medicine,and object identification.In this work,we experimentally demonstrate an LWIR multispectral image sensor with three wavelength bands using optical elements made of an aluminum(Al)-based plasmonic filter array sandwiched in germanium(Ge).To realize the multispectral sensor,the filter arrays are then integrated into a three-dimensional(3D)printed wheel stacked on a low-resolution monochrome thermal sensor.Our prototype device is calibrated using a blackbody and its thermal output has been enhanced with computer vision methods.By applying a state-of-theart deep learning method,we have also reconstructed multispectral images to a better spatial resolution.Scientifically,our work demonstrates a versatile spectral thermography technique for detecting target signatures in the LWIR range and other advanced spectral analyses.展开更多
Near-infrared germanium(Ge) photodetectors monolithically integrated on top of silicon-on-insulator substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from ...Near-infrared germanium(Ge) photodetectors monolithically integrated on top of silicon-on-insulator substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from sensing and health monitoring to object recognition and optical communications. In this work, we report on the highdata-rate performance pin waveguide photodetectors made of a lateral hetero-structured silicon-Ge-silicon(Si-Ge-Si) junction operating under low reverse bias at 1.55 μm. The pin photodetector integration scheme considerably eases device manufacturing and is fully compatible with complementary metal-oxide-semiconductor technology. In particular, the hetero-structured Si-Ge-Si photodetectors show efficiency-bandwidth products of^9 GHz at-1 V and ~30 GHz at-3 V, with a leakage dark current as low as ~150 nA, allowing superior signal detection of high-speed data traffic. A bit-error rate of 10-9 is achieved for conventional 10 Gbps, 20 Gbps, and25 Gbps data rates, yielding optical power sensitivities of-13.85 dBm,-12.70 dBm, and-11.25 dBm, respectively. This demonstration opens up new horizons towards cost-effective Ge pin waveguide photodetectors that combine fast device operation at low voltages with standard semiconductor fabrication processes, as desired for reliable on-chip architectures in next-generation nanophotonics integrated circuits.展开更多
Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer...Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.展开更多
基金This work was performed in part at the Melbourne Centre for Nanofabrication(MCN)in the Victorian Node of the Australian National Fabrication Facility(ANFF)This project received funding from the Linkage Grant from Australian Research Council(No.LP160101475)。
文摘A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture.With the advent of high-resolution image sensors and color filter technologies,multispectral imagers in the visible wavelengths have become popular with increasing commercial viability in the last decade.However,multispectral imaging in longwave infrared(LWIR,8-14μm)is still an emerging area due to the limited availability of optical materials,filter technologies,and high-resolution sensors.Images from LWIR multispectral cameras can capture emission spectra of objects to extract additional information that a human eye fails to capture and thus have important applications in precision agriculture,forestry,medicine,and object identification.In this work,we experimentally demonstrate an LWIR multispectral image sensor with three wavelength bands using optical elements made of an aluminum(Al)-based plasmonic filter array sandwiched in germanium(Ge).To realize the multispectral sensor,the filter arrays are then integrated into a three-dimensional(3D)printed wheel stacked on a low-resolution monochrome thermal sensor.Our prototype device is calibrated using a blackbody and its thermal output has been enhanced with computer vision methods.By applying a state-of-theart deep learning method,we have also reconstructed multispectral images to a better spatial resolution.Scientifically,our work demonstrates a versatile spectral thermography technique for detecting target signatures in the LWIR range and other advanced spectral analyses.
基金H2020 European Research Council(ERC)(ERC POPSTAR No.647342)
文摘Near-infrared germanium(Ge) photodetectors monolithically integrated on top of silicon-on-insulator substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from sensing and health monitoring to object recognition and optical communications. In this work, we report on the highdata-rate performance pin waveguide photodetectors made of a lateral hetero-structured silicon-Ge-silicon(Si-Ge-Si) junction operating under low reverse bias at 1.55 μm. The pin photodetector integration scheme considerably eases device manufacturing and is fully compatible with complementary metal-oxide-semiconductor technology. In particular, the hetero-structured Si-Ge-Si photodetectors show efficiency-bandwidth products of^9 GHz at-1 V and ~30 GHz at-3 V, with a leakage dark current as low as ~150 nA, allowing superior signal detection of high-speed data traffic. A bit-error rate of 10-9 is achieved for conventional 10 Gbps, 20 Gbps, and25 Gbps data rates, yielding optical power sensitivities of-13.85 dBm,-12.70 dBm, and-11.25 dBm, respectively. This demonstration opens up new horizons towards cost-effective Ge pin waveguide photodetectors that combine fast device operation at low voltages with standard semiconductor fabrication processes, as desired for reliable on-chip architectures in next-generation nanophotonics integrated circuits.
文摘Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.
