Subjects: Optics >> Detectors submitted time 2025-07-15
Abstract： Temperature detection is essential for evaluating the working condition of various physical, biological, and chemical systems. Optical temperature sensing tools, particularly resonator-based thermometers, have garnered significant attention due to their exceptional performance in selectivity, sensitivity and anti-electromagnetic interference. Recently developed thermometers based on optical whispering-gallery mode barcodes of the microbubble resonator achieve a large temperature range measurement and direct temperature readout. However, the large temperature variation may potentially result in inaccurate results due to similarities in spectra and inadequate precision caused by nonlinear collective shift. In this work, we have developed a novel and directly readable on-chip silicon-based Fano-enhanced thermometer utilizing a Mach-Zehnder interferometer configuration. The device comprises a fishbone waveguide and a curved strip waveguide coupled with an ultra-high Q racetrack microring resonator. The spectrum patterns of the thermometer are uniquely determined by the temperature and exhibit ultra-high slope ratio Fano resonances of over 2.0 ×104 dB/nm. Simultaneously, we have proposed a spectral analysis method to accurately derive actual temperatures, which enables an ultra-high detection resolution of 6.1×10–4 ℃ and a large measurement range of 65 ℃ by leveraging a temperature database. These advancements support precise and extensive temperature sensing applications.
Peer Review Status:
Awaiting Review
Subjects: Optics >> X-ray optics submitted time 2025-03-02
Abstract： Ghost imaging (GI), as a novel imaging technique, facilitates image acquisition under low light conditions through single pixel measurements, thus holding great potential in various application areas ranging from biomedical imaging, remote sensing imaging, biometrics, astronomy to 3D imaging. However, to reconstruct high resolution images, GI typically requires a large number of single pixel samplings, which is extremely time consuming and poses practical limitations to its applications. Parallel ghost imaging treats each pixel of the position sensitive detector as a bucket detector and simultaneously performs tens of thousands of ghost imaging in parallel. In previous work, we gradually achieved parallel ghost imaging with high pixel resolution, low dose, and ultra large field of view. Parallel ghost imaging has demonstrated excellent performance and great potential. All this is so exciting. But since all our experiments were carried out at synchrotron radiation facilities, with a series of almost luxurious conditions such as nearly infinite and continuous light supply time, monochromatic, pure, and energy adjustable X rays, expensive and precise experimental equipment, and complete supporting facilities, many peers lacking experimental conditions cannot replicate parallel ghost imaging. Meanwhile, the high cost also hinders its cross field integration. Furthermore, we got rid of the synchrotron radiation source and completed the pipeline style acquisition of parallel ghost imaging in a way that uses rough and inexpensive equipment and is most imitable by others. We achieved high quality ghost imaging with an effective pixel size of 8.03 \textmu m and an image size of 2880×2280 at a laboratory X ray source. The total cost of transforming an X ray computed tomography device into a parallel ghost imaging experimental platform is only \$40. Parallel ghost imaging has been generalized from synchrotron radiation sources to X ray tubes.
However, a key problem remains unsolved. The object arm signal on our laboratory light source was obtained through artificial fitting, and the true magnification relationship between the reference arm and the object arm has not been established. In synchrotron radiation, we achieved true magnification using different magnifying optical lens groups. On the one hand, such a set of lenses is very expensive, making the generalization of parallel ghost imaging difficult again. On the other hand, the flux of the X ray tube is very small, which leads to extremely low efficiency. In this work, we find that compared with the parallel beam of synchrotron radiation, the cone beam of the X ray tube naturally has the characteristic of true magnification by gradually moving the detector away from the light outlet. We only use one detector. When collecting the object arm signal, the detector is moved to a position 30 cm away from the light outlet, and when collecting the reference arm signal, the detector is moved to a position 150 cm away from the light outlet. These two positions form a true magnification relationship of 5 times, achieving super resolution of parallel ghost imaging on the X ray tube. A series of high quality ghost imaging results with an effective pixel size of 7.095 \textmu m and an image size of 2880×2280 in pipeline style acquisition were obtained. The realization of true magnification based on the X ray tube is a prerequisite for achieving ultra large field of view and low dose imaging. Completing this work at zero cost implies great application value and commercial potential.
Peer Review Status:Awaiting Review
Subjects: Chemistry >> Analytical Chemistry Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Preservation and Processing of Agricultural Products Subjects: Optics >> Spectroscopy Subjects: Food Science and Technology >> Package and Preservation of Food submitted time 2024-12-24
Abstract： Due to the oxidation of unsaturated fatty acids during storage, the taste and quality of Torreya grandis seeds declines. Unscrupulous merchants, seeking huge profits, blend Torreya stale seeds with fresh ones for sale, infringing upon consumers’ interests. A fast and non-destructive identification method is needed . Methods: In this research, near-infrared spectroscopy was used to conduct rapid and non-destructive discrimination on stale Torreya grandis seeds. Spectra of shelled Torreya grandis seeds samples were collected in the wavelength ranges of 200-1160 nm and 900-1700 nm using two near-infrared spectrometers. Nine methods were employed to preprocess the spectral data. Then, four wavelength selection methods, namely interval optimization selection algorithm (ICO), competitive adaptive reweighted sampling (CARS), successive projections algorithm (SPA), and variable combination population analysis (VCPA), were utilized to screen the spectral characteristic variables of stale Torreya grandis seeds. Linear discriminant analysis (LDA), support vector machine (SVM), and backpropagation neural network (BP) methods were applied to establish discrimination models for stale Torreya grandis seeds. Results: The results indicate that for spectrometer 1, the CARS method is the optimal wavelength selection method, and the CARS-SVM model exhibits the best performance, with sensitivity, specificity, and accuracy all reaching 100% in the prediction set. For spectrometer 2, standardization and SNV are superior preprocessing methods. The VCPA variable selection method outperforms the other three methods, and the established optimal model is VCPA-BP, with the sensitivity, specificity, and accuracy of the model’s prediction set being 98.18%, 93.02%, and 95.04%, respectively. Conclusions: Thus, it can be concluded that the discrimination models established based on the data from both spectrometers can effectively discriminate stale Torreya grandis seeds, and the overall performance of spectrometer 1 is superior to that of spectrometer 2. This study can provide a detection method for the rapid and non-destructive discrimination of stale Torreya grandis seeds, effectively guaranteeing the quality of Torreya grandis seeds.
Peer Review Status:Awaiting Review
Subjects: Optics >> Other areas of optics submitted time 2024-08-26
Abstract： Based on the Global Positioning System (GPS) range measurement equation whose correctness has been fully proven by GPS practices, we found that in an inertial system which is moving relative to the Earth Centered Inertial (ECI) frame, the propagation speed of light is neither constant nor isotropic, but , where v is the velocity of the system relative to the ECI frame and is the unit vector of the direction of light propagation. Utilizing an interferometer of two independent ultrastable lasers, a crucial experiment examining this important scientific problem with a low translational speed of the interferometer is proposed; and its comparison with an existing experiment of the generalized Sagnac effect is also presented. Besides, such an interferometer can be utilized to examine another important scientific problem: whether the speed of light is isotropic or not on rotating Earth’s surface. Because the vast majority of optical laboratories on the surface of the Earth have high linear velocities of the Earth’s rotation, only a small change of the orientation of the interferometer is sufficient.
Peer Review Status:Awaiting Review
Subjects: Optics >> Fiber optics and optical communications Subjects: Electronics and Communication Technology >> Optoelectronics and Laser submitted time 2024-08-17
Abstract： Optical neural networks have long cast researchers’ attention nowadays. Like other optical structured neural networks, fiber neural networks which utilize the mechanism of light transmission to compute can take great advantages in both computing efficiency and power cost. Though the potential ability of optical fiber was demonstrated via the establishing of fiber neural networks, it will be of great significance of combining both fiber’s transmission and computing functions so as to cater the needs of future beyond 5G intelligent communication signal processing. Thus, in this letter, the fiber neural networks and their related optical signal processing methods will be both developed. In this way, information derived from the transmitted signals can be directly processed in the optical domain rather than being converted to the electronic domain. As a result, both prominent gains in processing efficiency and power cost can be further obtained. The fidelity of the whole structure and related methods is demonstrated by the task of modulation format recognition which plays important role in today’s fiber optical communications without losing the generality.
Peer Review Status:Awaiting Review
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