- Oct. 08, 2024
- Vol. 1, Issue 2 (2024)
- Sep. 25, 2024
- Vol. , Issue (2024)
- Sep. 25, 2024
- Vol. , Issue (2024)
- Sep. 25, 2024
- Vol. , Issue (2024)
- Sep. 20, 2024
- Vol. 12, Issue 8 (2024)
We demonstrate, for the first time and to the best of our knowledge, a continuous-wave and broadly tunable Cr:ZnSe bulk crystal laser pumped by a Tm:YLF b
We demonstrate, for the first time and to the best of our knowledge, a continuous-wave and broadly tunable Cr:ZnSe bulk crystal laser pumped by a Tm:YLF bulk laser with 1845 nm and 1887 nm wavelengths. We compare the output characteristics and wavelength-tuning properties of the continuous-wave operation at the two pump wavelengths. In the continuous-wave operation, the maximum output power is 1.79 W with a slope efficiency of 28.8%, which is achieved at the pump wavelength of 1887 nm. In addition, a tuning range of ∼700 nm (696 nm) from 2040 nm to 2736 nm by using a reflective diffraction grating is realized. To the best of our knowledge, this is the widest tuning range realized so far for Cr:ZnSe bulk crystal tuned by gratings.show less
- Oct.14,2024
- Chinese Optics Letters,Vol. 22, Issue 10
- 101404 (2024)
Prof. Philip Russell (Max Planck Institute for the Science of Light) discusses the development of photonic crystal fibers, in a conversation with Prof. Lo
Prof. Philip Russell (Max Planck Institute for the Science of Light) discusses the development of photonic crystal fibers, in a conversation with Prof. Long Zhang (Chinese Academy of Sciences).show less
- Oct.12,2024
- Advanced Photonics,Vol. 6, Issue 6
- 060501 (2024)
Polarimetric imaging, leveraging measurements of polarimetric parameters that encode distinct physical properties, finds wide applications across diverse
Polarimetric imaging, leveraging measurements of polarimetric parameters that encode distinct physical properties, finds wide applications across diverse domains. However, some critical polarization information is highly sensitive to noise, and denoising polarimetric images while preserving polarization information remains a challenge. The development of denoising techniques for polarized images can be roughly divided into three stages: The first stage involves the direct application of traditional image denoising algorithms, such as spatial/transform domain filtering. The second stage involves specially designed methods for polarized images, using image prior models for noise removal, such as principal component analysis and K-singular value decomposition. In the third stage, benefiting from advances in deep learning, denoising methods tend to integrate polarization characteristics with deep learning models for noise suppression. The residual dense network, U-Net, and other effective models are appropriately modified and supervised/self-supervised trained to handle the denoising problem of regular/extensive polarimetric images. In this paper, we perform a comparative study of polarimetric image denoising methods. These methods are first classified as learning-based and traditional methods. Then, the motivations and principles of different types of denoising methods are analyzed. Finally, some potential challenges and directions for future research are pointed out.show less
- Oct.11,2024
- Advanced Imaging,Vol. 1, Issue 2
- 022001 (2024)
Suppressing mode degradation is the key issue for high-power laser delivery; however, diagnosing mode degradation in its entirety, ranging from the conten
Suppressing mode degradation is the key issue for high-power laser delivery; however, diagnosing mode degradation in its entirety, ranging from the contents and origins to locations, has always been a major obstacle. Here, a versatile approach for tracing the origins of mode coupling is demonstrated through addressing the differential intermodal dispersions of fiber modes. Full recognition for modal contents and the origins of mode degradation are experimentally completed in a two-mode fiber laser delivery system, which assists a significant improvement of beam quality M2 from 1.35 to 1.15 at the highest power of over 300 W. This method yields a quantitative characterization for manipulating the individual mode of dual-mode coupling origins or their combinations. This work points toward a promising strategy for the online tracing of mode coupling in cascade fiber links, thus enabling further pursuit of seeking extreme beam quality in high-power fiber laser systems.show less
- Oct.10,2024
- High Power Laser Science and Engineering,Vol. 12, Issue 5
- 05000e54 (2024)
The microring resonator (MRR) plays important roles in signal processing because high quality band-pass filtering can be obtained at its drop port. To promote signal to noise ratio, a high rejec
The microring resonator (MRR) plays important roles in signal processing because high quality band-pass filtering can be obtained at its drop port. To promote signal to noise ratio, a high rejection ratio is significantly demanded. However, it is still challenging to promote the rejection ratio of the MRR-based band-pass filter. To solve this problem, we propose to use an all-pass filter (APF) to enhance the rejection ratio of the MRR-based band-pass filter. Experimental results show that the improved rejection ratio is as high as 47.7 dB, which is improved by 23.6 dB compared with that of the MRR. Meanwhile, the bandwidth of the MRR-based band-pass filter is reduced from 2.61 to 1.14 GHz thanks to the constructive interference in the passband. Additionally, the center frequency of this ultra-high rejection MRR can be continuously tuned from 6.26 to 46.25 GHz. The quality(Q) of the MRR is improved from 7.4×104 to 1.7×105.During the adjustment, the rejection ratio of the band-pass filter remains exceeding 40 dB. The proposed approach can be used to achieve optical bandpass filters with high performance.show less
- Oct.15,2024
- Advanced Photonics Nexus,Vol. 3, Issue 6
Spectroscopy, especially for plasma spectroscopy, provided a powerful platform for biological and material analysis with their elemental and molecular fingerprinting capability. AI has the treme
Spectroscopy, especially for plasma spectroscopy, provided a powerful platform for biological and material analysis with their elemental and molecular fingerprinting capability. AI has the tremendous potential to build a universal quantitative framework covering all branches of plasma spectroscopy based on its unmatched representation and generalization ability. Herein, we introduce an AI-based unified method called self-supervised image-spectrum twin information fusion detection (SISTIFD) to collect twin co-occurrence signals of the plasma and to intelligently predict the physical parameters for improving the performances of all plasma spectroscopic techniques. It can fuse the spectra and plasma images in synchronization, derive the plasma parameters and provide accurate results. The experiments demonstrates its excellent utility and capacity with 98% reduction in evaluation indexes and 143 Hz of analysis frequency. Besides, as a completely end-to-end and self-supervised framework, the SISTIFD enables automatic detection without manual preprocessing or intervention. With these advantages, it remarkably enhanced various plasma spectroscopic techniques with state-of-the-art performance and unsealed their possibility in industry, especially in the regions that require both capability and efficiency. This scheme brings new inspiration to the whole field of plasma spectroscopy, and enables in-situ analysis with a real-world scenario of high throughput, cross-interference, various analyte complexity, and diverse applications.show less
- Oct.15,2024
- Advanced Photonics Nexus,Vol. 3, Issue 6
Proton acceleration in a near-critical-density gas driven by a light spring (LS) pulse with a helical structure in its intensity profile is investigated using three-dimensional particle-in-cell
Proton acceleration in a near-critical-density gas driven by a light spring (LS) pulse with a helical structure in its intensity profile is investigated using three-dimensional particle-in-cell simulations. Compared with other pulse modes with the same laser power, such as the Gaussian pulse or the donut Laguerre–Gaussian (LG) pulse, the LS structure significantly enhances the peak intensity and drives a stronger longitudinal acceleration field and transverse focusing field. Therefore, it is very promising to obtain ultrahigh-energy protons using LS pulses with a relatively lower power. For example, by using LS pulses with the same power of 4.81 PW, the proton in the gas can be accelerated up to 8.7 GeV, and the witness proton can be accelerated to 10.6 GeV from 0.11 GeV, which shows the overwhelming advantage over the Gaussian and LG pulse casesshow less
- Oct.14,2024
- High Power Laser Science and Engineering
This article introduces a novel fiber-based picosecond burst-mode laser system capable of operating at high power and high repetition rates. A pulse-circulating fiber ring was developed as a bur
This article introduces a novel fiber-based picosecond burst-mode laser system capable of operating at high power and high repetition rates. A pulse-circulating fiber ring was developed as a burst generator, achieving an intra-burst repetition rate of 469 MHz without the need for a high-repetition-rate seed source. This design also allows for flexible adjustment of the number of sub-pulses, burst repetition rate, and burst shape. Additionally, a master oscillator power amplifier (MOPA) was employed to analyze the amplification characteristics of bursts. The system demonstrated a maximum average power of 606 W, with a measured sub-pulse duration of 62 ps and the highest sub-pulse peak power of 980 kW. To the best of our knowledge, this marks the highest average power obtained in burst-mode ultrafast lasers. Such a laser system holds potential for applications in precision manufacturing, high-speed imaging, high-precision ranging, and other diverse domains.show less
- Oct.14,2024
- High Power Laser Science and Engineering