A POF detector, using a convex spherical aperture microstructure probe, is designed for low-energy and low-dose rate gamma-ray detection in this letter. The profound impact of the probe micro-aperture's depth on the detector's angular coherence is evident from both simulation and experimental results, which also demonstrate this structure's heightened optical coupling efficiency. Modeling the connection between angular coherence and micro-aperture depth allows for the determination of the optimal micro-aperture depth. find more At 595 keV and a dose rate of 278 Sv/h, the fabricated POF detector achieves a sensitivity of 701 counts per second. The average count rate at differing angles exhibits a maximum percentage error of 516%.
A gas-filled hollow-core fiber is instrumental in the nonlinear pulse compression of a high-power, thulium-doped fiber laser system, which is presented in this report. Emitted at a central wavelength of 187 nanometers, a sub-two cycle source delivers a pulse with an energy of 13 millijoules, a peak power of 80 gigawatts, and an average power of 132 watts. So far, according to our knowledge, the highest average power from a few-cycle laser source within the short-wave infrared spectrum is this one. This laser source, distinguished by its potent combination of high pulse energy and high average power, is a premier driver for nonlinear frequency conversion, encompassing terahertz, mid-infrared, and soft X-ray spectral ranges.
We demonstrate whispering gallery mode (WGM) lasing originating from CsPbI3 quantum dots (QDs) that are deposited onto the surface of TiO2 spherical microcavities. CsPbI3-QDs gain medium's photoluminescence emission is strongly coupled with the resonating optical cavity structure of TiO2 microspheres. A distinct threshold of 7087 W/cm2 marks the point where spontaneous emission in these microcavities transforms into stimulated emission. The power density's increase by an order of magnitude beyond the threshold point, when microcavities are illuminated by a 632-nm laser, causes a three- to four-fold surge in lasing intensity. WGM microlasing, functioning at room temperature, showcases quality factors exceeding Q1195. The quality factor is found to be substantially greater for TiO2 microcavities of 2 meters. Even after 75 minutes of continuous laser irradiation, CsPbI3-QDs/TiO2 microcavities displayed no degradation in photostability. Within the realm of WGM-based tunable microlasers, CsPbI3-QDs/TiO2 microspheres are a promising avenue for exploration.
Simultaneous measurement of rotational speeds in three dimensions is accomplished by a crucial three-axis gyroscope, a component of an inertial measurement unit. A novel fiber-optic gyroscope (RFOG) configuration, employing a three-axis resonant design and a multiplexed broadband light source, is introduced and validated. To enhance power utilization from the source, the output light from the two unused ports of the central gyroscope fuels the two axial gyroscopes. Interference stemming from different axial gyroscopes is avoided by adjusting the lengths of three fiber-optic ring resonators (FRRs) within the multiplexed link, instead of incorporating additional optical elements. Employing optimal component lengths effectively suppresses the input spectrum's influence on the multiplexed RFOG, achieving a theoretical bias error temperature dependence of just 10810-4 per hour per degree Celsius. Finally, a three-axis RFOG, with its precision calibrated for navigation, is demonstrated utilizing a fiber coil of 100 meters per FRR.
Deep learning networks have proven effective in enhancing the reconstruction performance of under-sampled single-pixel imaging (SPI). Deep-learning SPI methods employing convolutional filters encounter difficulties in representing the long-range interconnections within SPI measurements, thereby impacting the quality of the reconstruction. The transformer's noteworthy capability to capture long-range dependencies is, however, counterbalanced by its deficiency in local mechanisms, which detracts from its performance when directly utilized for under-sampled SPI. We advocate for a high-quality, under-sampled SPI method in this letter, utilizing a locally-enhanced transformer, novel in our estimation. The local-enhanced transformer, beyond capturing the global dependencies in SPI measurements, further possesses the ability to model local dependencies. Optimal binary patterns are employed in the proposed method, leading to high sampling efficiency and being advantageous for hardware implementation. find more The performance of our proposed method, evaluated on synthetic and real-world data, demonstrably outperforms the leading SPI approaches.
Multi-focus beams, a novel category of structured light beams, demonstrate self-focusing properties at multiple points during their propagation. This study demonstrates that the proposed beams are capable of generating multiple longitudinal focal spots; moreover, the manipulation of the initial beam parameters allows for precise control of the number, intensity, and position of the resulting focal spots. The self-focusing behavior of these beams persists, even when they pass through the shadow region of an obstruction. By generating these beams experimentally, we have obtained results that concur with the anticipated theoretical outcomes. Our investigations may have applications in scenarios necessitating precise longitudinal spectral density control, including, but not limited to, longitudinal optical trapping and manipulation of multiple particles, and the process of cutting transparent materials.
Up to this point, a considerable number of studies have explored multi-channel absorbers for conventional photonic crystals. Nevertheless, the restricted and unpredictable number of absorption channels cannot support the needs of applications, such as multispectral or quantitative narrowband selective filtering. Theoretically, a tunable and controllable multi-channel time-comb absorber (TCA) is proposed, employing continuous photonic time crystals (PTCs) to tackle these issues. In contrast to conventional PCs with a constant refractive index, this system generates a more intense localized electric field within the TCA by harnessing externally modulated energy, leading to distinct, multiple absorption peaks. To achieve tunability, it is necessary to modify the refractive index (RI), angle, and the time period (T) of the phase transition crystals (PTCs). The TCA's adaptability, stemming from diversified tunable methods, opens doors to a wider range of applications. Concomitantly, varying T can alter the number of multi-faceted channels. Fundamental to controlling the occurrences of time-comb absorption peaks (TCAPs) in multiple channels is the modification of the primary coefficient in n1(t) of PTC1, and a mathematical framework detailing the relationship between coefficients and the number of channels has been established. Applications in the design of quantitative narrowband selective filters, thermal radiation detectors, optical detection instruments, and other technologies are anticipated.
Employing a large depth of field, optical projection tomography (OPT) acquires projection images of a sample from diverse orientations to construct a three-dimensional (3D) fluorescence image. The practice of applying OPT typically centers on millimeter-sized specimens due to the difficulty in rotating microscopic samples and its incompatibility with the constraints of live-cell imaging. Fluorescence optical tomography of a microscopic specimen is demonstrated in this letter, utilizing lateral translation of the tube lens within a wide-field optical microscope. This technique allows for high-resolution OPT without sample rotation. The field of view is diminished to approximately the halfway point in the direction of the tube lens translation, this being the cost. By examining bovine pulmonary artery endothelial cells and 0.1mm beads, we evaluate the 3D imaging performance of the proposed method in comparison with the standard objective-focus scanning method.
Applications like high-energy femtosecond pulse generation, Raman microscopy, and precise timing distribution heavily rely on the synchronization of lasers operating at different wavelengths. Synchronized triple-wavelength fiber lasers, emitting light at 1, 155, and 19 micrometers, respectively, were realized by integrating coupling and injection configurations. Ytterbium-doped fiber, erbium-doped fiber, and thulium-doped fiber, each contributing to the laser system, are present in the three fiber resonators, respectively. find more In these resonators, ultrafast optical pulses are fashioned by the passive mode-locking technique, using a carbon-nanotube saturable absorber. During the synchronization process, the synchronized triple-wavelength fiber lasers, through the meticulous adjustment of variable optical delay lines in their fiber cavities, attain a maximum cavity mismatch of 14mm. Simultaneously, we investigate the synchronization traits of a non-polarization-maintaining fiber laser in an injection configuration. A fresh insight, as far as we know, is provided by our results on multi-color synchronized ultrafast lasers that demonstrate broad spectral coverage, high compactness, and a tunable repetition rate.
In numerous applications, fiber-optic hydrophones (FOHs) are instrumental in the detection of high-intensity focused ultrasound (HIFU) fields. Uncoated single-mode fiber, with a perpendicularly cleaved end, forms the most common type The chief shortcoming of these hydrophones is their low signal-to-noise ratio (SNR). Signal averaging is crucial for increasing SNR, but the resulting increase in acquisition time obstructs ultrasound field scan capabilities. To increase SNR and maintain robustness against HIFU pressures, the bare FOH paradigm in this study is modified to include a partially reflective coating at the fiber's end face. A numerical model, utilizing the general transfer-matrix method, was developed here. The simulation data led to the creation of a single-layer FOH coated with 172nm of TiO2. The hydrophone's capacity to function across the frequency spectrum from 1 to 30 megahertz was verified. In acoustic measurements, the SNR improvement was 21dB when using a coated sensor compared to an uncoated sensor.