Determining the trap density in the absorbing layer thin film of perovskite solar cells is a important task, as it exerts a direct influence on the efficiency of the devices. Here, we proposed t

Determining the trap density in the absorbing layer thin film of perovskite solar cells is a important task, as it exerts a direct influence on the efficiency of the devices. Here, we proposed the utilization of time-resolved photoluminescence (TRPL) as a non-destruction method to evaluate trap density. A model has been formulated to investigate carrier recombination and transition processes in perovskite materials, subsequently employed for numerical computations and successfully fitted to TRPL signals. Moreover, a genetic algorithm was implemented to optimize the relevant parameters. Finally, statistical methodologies were applied to obtain the parameters associated with the trap states inherent to the material. This comprehensive approach facilitates the successful determination of trap densities across varying samples, enabling clear differentiation.show less

We establish a quantum theory of computational ghost imaging and propose quantum projection imaging where object information can be reconstructed by quantum statistical correlation between a cer

We establish a quantum theory of computational ghost imaging and propose quantum projection imaging where object information can be reconstructed by quantum statistical correlation between a certain photon number of bucket signal and DMD random patterns. The reconstructed image can be negative or positive depending on the chosen photon number. In particular, the vacuum state (zero-number) projection produces a negative image with better visibility and contrast-to-noise ratio. The experimental results of quantum projection imaging agree well with theoretical simulations and show that, under the same measurement condition, vacuum projection imaging is superior to conventional and fast first-photon ghost imaging in low-light illumination.show less

A high-performance silicon arrayed-waveguide grating (AWG) with 0.4-nm channel spacing for dense wavelength-division multiplexing (DWDM) systems is designed and realized successfully. The device

A high-performance silicon arrayed-waveguide grating (AWG) with 0.4-nm channel spacing for dense wavelength-division multiplexing (DWDM) systems is designed and realized successfully. The device design involves broadening the arrayed waveguides far beyond the singlemode regime, which minimizes random phase errors and propagation loss without requiring any additional fabrication steps. To further enhance performance, Euler-bends have been incorporated into the arrayed waveguides to reduce the device’s physical footprint and suppress the excitation of higher-modes. Additionally, shallowly-etched transition regions are introduced at the junctions between the free-propagation regions and the arrayed waveguides to minimize mode mismatch losses. As an example, a 32×32 AWG (de)multiplexer with a compact size of 900×2200 μm2 is designed and demonstrated with a narrow channel spacing of 0.4 nm by utilizing 220-nm-thick silicon photonic waveguides. The measured excess loss for the central channel is approximately 0.65 dB, the channel non-uniformity is around 2.5 dB, while the adjacent-channel crosstalk of the central output port is −21.4 dB. To the best knowledge, this AWG (de)multiplexer is the best one among silicon-based implementations currently available, offering both dense channel spacing and a large number of channels.show less

Neurodegenerative diseases, such as Parkinson's and Alzheimer's disease, affect the elderly worldwide and will become more prevalent as the global population ages. Neuroinflammation is a

Neurodegenerative diseases, such as Parkinson's and Alzheimer's disease, affect the elderly worldwide and will become more prevalent as the global population ages. Neuroinflammation is a common characteristic of neurodegenerative diseases. By regulating the phenotypes of microglia, it is possible to suppress neuroinflammation and, in turn, help prevent neurodegenerative diseases. This work reports a non-invasive photonic approach of regulating microglia from over-excited M1/ M2 to the resting M0 phenotype using a special NIR light emitted by the SrGa12O19:Cr3+ phosphor. The absorbance and internal and external quantum efficiencies of the optimal Sr(Ga0.99Cr0.01)12O19 phosphor synthesized at 1400 oC for 8 h using 1%H3BO3+1%AlF3 as flux were 53.9%, 99.2%, and 53.5%; and the output power and energy-conversion efficiency of the LED device packaged using the optimal SrGa12O19:Cr3+ phosphor driven at 20 mA reach unprecedentedly 19.69 mW and 37.58%, respectively. The broadband emission of the NIR LED device covers the absorption peaks of cytochrome c oxidase well; and the NIR light can efficiently promote the proliferation of microglia, produce ATP (Adenosine-triphosphate triphosphate), reverse overexcitation, alleviate and inhibit inflammation, and improve cells survival rate and activity, showing great promising for photomedicine application.show less