Heatmap-based cattle pose estimation methods suffer from high network complexity and low detection speed. Addressing the issue of cattle pose estimation for complex scenarios without heatmaps, an end-to-end, lightweight cattle pose estimation network utilizing a reparameterized network and an attention mechanism is proposed to improve the overall network performance. The EfficientRepBiPAN (Efficient Representation Bi-Directional Progressive Attention Network) module, incorporated into the neck network, adeptly captures target features across various scales while also mitigating model redundancy.
View Article and Find Full Text PDFWe model and demonstrate a self-matching photonic lantern (SMPL) device, which is designed to address the constraint of limited transverse modes generated by fiber lasers. The SMPL incorporates a FMF into the array at the input end of a traditional photonic lantern. The few-mode fiber at the output end is specifically configured to align with the few-mode fiber at the input, therefore named as SMPL.
View Article and Find Full Text PDFMicrofluidics is an increasingly popular method for studying cell deformation, with various applications in fields such as cell biology, biophysics, and medical research. Characterizing cell deformation offers insights into fundamental cell processes, such as migration, division, and signaling. This review summarizes recent advances in microfluidic techniques for measuring cellular deformation, including the different types of microfluidic devices and methods used to induce cell deformation.
View Article and Find Full Text PDFThis paper proposes an ultra-narrow band solid state optical filter with Voigt anomalous dispersion at 1530 nm based on Er: LiYF, sets a theoretical model for its realization of ultra-narrow band optical filtering, and performs simulations based on the model. The results show that the maxi-mum transmission of the filter is close to 80%, while the line-width is only in the order of 100 MHz, while its transmission peak can be tuned flexibly by adjusting the magnetic field. This filter has a natural advantage in space laser communications, which is another promising ultra-narrow band optical filter.
View Article and Find Full Text PDFNanomaterials (Basel)
October 2021
To date, the mechanisms of Er upconversion luminescence via 980 and 1530 nm excitation have been extensively investigated; however, based on discussions, they either suffer from the lack of convincing evidence or require elaborated and time-consuming numerical simulations. In this work, the steady-state and time-resolved upconversion luminescence data of Er-doped NaYF were measured; we therefore investigated the upconversion mechanisms of Er on the basis of the spectroscopic observations and the simplified rate equation modeling. This work provides a relatively simple strategy to reveal the UCL mechanisms of Er upon excitation with various wavelengths, which may also be used in other lanthanide ion-doped systems.
View Article and Find Full Text PDFAn optoelectronic swept-frequency laser (SFL) is an optoelectronic feedback system that includes an auxiliary interferometer that can exert precise control over the optical frequency sweep. The arm-length difference (ALD) of the auxiliary interferometer directly affects the performance of the whole system. We established a theoretical model to choose the optimal ALD of an auxiliary interferometer in an optoelectronic SFL system using a frequency-modulated continuous-wave reflectometry experimental setup.
View Article and Find Full Text PDFIn this design, we introduced a surface plasmon resonance (SPR) fiber-sensing probe into a column chromatography (CC) system to realize on-line dynamic detection in sample separation. The refractive index of the gel around the probe would be adjusted dynamically by the concentration change of the sample during CC separation. To demonstrate the separation and on-line detection process, bovine serum albumin (BSA) and riboflavin-5-phosphate sodium (FMN-Na) are chosen as the analytes in a Sephadex gel filtration chromatography system.
View Article and Find Full Text PDFParticle size significantly affects the brightness of luminescent nanocrystals. Herein we firstly adopt a 1530 nm CW laser as the optical heating source to increase the particle size of Er heavily doped nanocrystals, leading to giant enhancement of the luminescent intensity. The advantages of this method are mainly feature along the facile route, with an ultrafast process, and low threshold of the laser power density.
View Article and Find Full Text PDFRemotely monitoring and regulating temperature in a small area are of vital importance for hyperthermia therapy. Herein, we report ~11 nm NaErF nanocrystal as the ultra-small nanoheater, which is highly safe for biological applications. Under 1530 nm photon excitation, upconversion intensity of NaErF is significantly enhanced as compared to the conventionally used 980 nm pumping source.
View Article and Find Full Text PDFImproving luminescence efficiency is of vital importance for applications of rare-earth-doped upconversion materials. Herein, we present highly efficient upconversion nanocrystal, which is brighter than the state-of-the-art Er/Yb co-doped core-shell material, through Er heavily doping and 1530 nm excitation. Moreover, upconversion characteristics and mechanisms of Er heavily doped core nanocrystals and their core-shell counterparts are investigated carefully.
View Article and Find Full Text PDFTransition probability is of vital importance for luminescence process, whereas the effects of doping concentration have not been explored in the Er:NaGdF. In this work, we investigate the radiative transition probabilities of Er highly doped NaGdF sub 10 nm nanocrystals using J-O theory. It is found that the transition probabilities vary with changing Er concentration, especially altering the ratio of ErH to S level, which is highly useful for optical thermometers as they are thermally coupled.
View Article and Find Full Text PDFThis paper proposes a simple, stable, sensitive, and angle-dependent localized surface plasmon resonance (LSPR) sensing structure based on multi-mode optical fiber. We adopted the template transfer method to integrate a nanohole array onto a fiber tip with beveled angle. Experimental results indicated that beveled angle structured probe sensor outperform the flat optical fiber tip structured LSPR sensor in our experiment.
View Article and Find Full Text PDFThe FIR (fluorescence intensity ratio) technique for optical thermometry has attracted considerable attention over recent years due to its high sensitivity and high spatial resolution. However, it is thought that a heating effect induced by incident light may lead to temperature overestimations, which in turn impedes the reliability of this technique for applications which require high levels of accuracy. To further improve the FIR technique, this paper presents a modified calibration expression, which is suitable for surface temperature sensing, based on the temperature distribution (calculated through COMSOL software).
View Article and Find Full Text PDFWe propose and demonstrate a whispering gallery mode (WGM) resonance-based temperature sensor, where the microresonator is made of a DCM (2-[2-[4-(dimethylamino)phenyl] ethenyl]-6-methyl-4H-pyran-4-ylidene)-doped oil droplet (a liquid material) immersed in the water solution. The oil droplet is trapped, controlled, and located by a dual-fiber optical tweezers, which prevents the deformation of the liquid droplet. We excite the fluorescence and lasing in the oil droplet and measure the shifts of the resonance wavelength at different temperatures.
View Article and Find Full Text PDFWe propose and demonstrate an effective method to adjust the dynamic range of a fiber surface plasmon resonance (SPR) sensor by introducing a multimode fiber-sensing probe with a dual-truncated-cone (DTC) structure. When the grind angle of the DTC structure increases, the dynamic range redshifts. Based on this result, we fabricate a quasi-distributed two-channel multimode fiber SPR sensor by cascaded-connecting a DTC-sensing probe of 14° grind angle and a traditional transmitted multimode fiber (TMF)-sensing probe in the same fiber.
View Article and Find Full Text PDFWe report on the first demonstration of a single-fiber optical tweezer that is utilized to stabilize and control the liquid droplet for dye lasing. In order to trap a liquid droplet with a diameter of 15-30 μm, an annular core micro-structured optical fiber is adopted. By using wavelength division multiplexing technology, we couple a trapping light source (980 nm) and a pumping light source (532 nm) into the annular core of the fiber to realize the trapping, controlling, and pumping of the oil droplet.
View Article and Find Full Text PDFWe propose and demonstrate a distributed surface plasmon resonance (SPR) fiber sensor based on a novel, simple, and effective incident angle adjusting method. For normal fiber SPR sensors, it is hard to realize distributed sensing because it is hard to produce two dynamic ranges (resonance wavebands) with a great difference. The dynamic range depends on the incident angle, and therefore, we propose an incident angle adjusting method that is implemented by grinding an eccentric-core fiber to different angles, which helps to produce different SPR wavebands with great difference, thus realizing distributed sensing.
View Article and Find Full Text PDFBy using a twin-core fiber (TCF), we propose and demonstrate a novel distributed SPR sensor, which employs both the time division multiplexing (TDM) technology and the wavelength division multiplexing (WDM) technology together. The proposed sensor has two sensing passages with four sensing channels (and there are two sensing channels in each sensing passage). We employ the TDM technology to realize the two passage distributed sensing, which are parallel-connection; and we employ the WDM technology to realize the distributed sensing of two channels in a sensing passage, which are series-connected.
View Article and Find Full Text PDFWe propose and demonstrate a novel surface plasmon resonance (SPR)-sensing approach by using the fundamental mode beam based on a twin-core fiber (TCF). Although normally in a fiber SPR sensor, a multimode fiber (MMF) has often been used to improve the coupling efficiency; for improving fiber SPR sensor sensitivity, single-mode beam is optimal. We provide a novel method to employ the single (fundamental)-mode beam to SPR sense based on the TCF.
View Article and Find Full Text PDFEfficient and controllable launching function of an optical tweezers is a challenging task. We present and demonstrate a novel single fiber optical tweezers which can trap and launch (clean) a target polystyrene (PS) microsphere (diameter~10μm) with independent control by using two wavelengths beams: 980nm and 1480nm. We employ 980nm laser beam to trap the target PS microsphere by molding the fiber tip into a special tapered-shape; and we employ 1480nm laser beam to launch the trapped PS microsphere with a certain velocity by using the thermophoresis force generated from the thermal effect due to the high absorption of the 1480nm laser beams in water.
View Article and Find Full Text PDFA new kind of optofluidic in-fiber integrated device based on a specially designed hollow optical fiber with an inner core is designed. The inlets and outlets are built by etching the surface of the optical fiber without damaging the inner core. A reaction region between the end of the fiber and a solid point obtained after melting is constructed.
View Article and Find Full Text PDFA fiber optic integrated modulation-depth-tunable modulator based on a type of hollow optical fiber with suspended core is proposed and investigated. We synthesized magnetic fluid containing superparamagnetic Fe(3)O(4) nanoparticles and encapsulated it in the hollow optical fiber as the cladding layer of the suspended core by fusing the hollow optical fiber with the multimode optical fibers. The light with a wavelength of 632.
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