Qiankun Zhang's research while affiliated with Beijing Information Science and Technology University and other places

... In contrast, the mean square error loss function has led to a lower classification performance but a higher signal-to-noise ratio of the output signal. Equation (28) and Equation (30) show the difference between the two loss functions, which is the crucial factor leading to this phenomenon: the MSE affects the intensity distribution among all the detectors while the SCE uses an interclass competition mechanism, focusing on the intensity distribution within the detector area while disregarding the intensity distribution outside of it. The fully connected topology is the basis for designing diffractive neural networks [14], which implies that every neuron in a layer can be connected to all neurons in the next layer. ...

... Since graphene was successfully synthesized in 2004 [32], plenty of two-dimensional (2D) materials have been developed, including black phosphorus (BP) [33,34], transition metal dichalcogenides (TMDCs) [35,36], topological insulators (TIs) [37], and so forth [28,[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. These materials have attracted considerable attention in photonics and 2 of 18 optoelectronic fields due to their advantageous properties, such as high room temperature carrier mobility [53,54], tunable bandgap [55,56], fast response speed [57,58], ultrabroadband optical response, and absorption [59,60]. Based on these fascinating properties, some representative progresses about IR technology have been exhibited, which prove that 2D materials hold great potential for high-performance IR photonics and optoelectronic applications [61][62][63][64]. ...

... However, the lack of a bottom-up approach for film fabrication limits its practical applications, and issues of the degradation of BP for applying a designed thickness to form high-quality surfaces have been investigated. Wet chemical and thermal treatment require not only controlling the thickness of BP flake but also maintaining its stability [11,12]. Conductive atomic force microscope anodic oxidation and electron beam sculpting were reported to accomplish nanopatterning and layer-by-layer thinning of BP [13,14]. ...

... Furthermore, The FBAR quality factor is a dimensionless quantity that represents the resonator's underdamped performance and expressed the correlation between the resonator bandwidth and its center frequency [279,280]. On other hand, the quality factor is well known and defined as the ratio of the energy stored in the resonator to the energy dissipated for each electromechanical conversion cycle [281,282], as presented in Eq. (8): where the Energy stored is represented the vibration energy stored in the resonator which is divided by the energy of the vibration that dissipated per each cycle. The device with a high-quality factor usually has less energy dissipation per each cycle. ...

... A promising approach to achieve both carrier doping and layer thickness control is light-assisted posttreatment of layered TMDs. [27][28] In this work, we exploit ultraviolet (UV) light irradiation to selectively realize surface modification and layer thinning of MoS2 in silver ionic (Ag + ) solution (Figure 1a). The experimental results show that under UV light exposure in Ag + solution environment, nanostructured silver ultrathin films (~2.9 nm) are uniformly decorated on 1L MoS2 surfaces, meanwhile the thickness of MoS2 from few-layer to bulk crystals could be thinned down to the atomic monolayer limit. ...

... Patil et al. [157] used fine gold nanoparticles doped with porous carbon as electrode materials to fabricate flexible biosensors with high accuracy and reliable operation for the detection of pH and uric acid levels in body fluids. Zhang et al. [158] developed a freestanding flexible film made of graphene/EC nanocomposite, which was integrated with a PET substrate. This gave rise to a highly sensitive flexible gas sensor with an ultra-low strain response. ...

... Optofluidic refractometers embedding optical microresonators within microfluidic devices are shown to be powerful and universal devices for RI sensing applications [1]. They can be used to monitor the RI of either a homogeneous medium such as gases and liquids [2][3][4][5][6] or non-homogeneous medium, especially colloidal suspensions with various applications to milk [7], waterborne bacteria [8], blood [9] and urine [10] to name a few application areas of high interest. ...