Simple Laser Research Articles

Room-Temperature Solid-State Maser Amplifier

Masers once represented the state of the art in low-noise microwave amplification technology but eventually became obsolete due to their need for cryogenic cooling. Masers based on solid-state spin systems perform most effectively as amplifiers, since they provide a large density of spins and can, therefore, operate at relatively high powers. While solid-state maser oscillators have been demonstrated at room temperature, continuous-wave amplification in these systems has only ever been realized at cryogenic temperatures. Here, we report on a continuous-wave solid-state maser amplifier operating at room temperature. We achieve this feat using a practical setup that includes an ensemble of nitrogen-vacancy center spins in a diamond crystal, a strong permanent magnet, and a simple laser diode. We describe important amplifier characteristics including gain, bandwidth, compression power, and noise temperature and discuss the prospects of realizing a room-temperature near-quantum-noise-limited amplifier with this system. Finally, we show that in a different mode of operation the spins can be used to reduce the microwave noise in an external circuit to cryogenic levels, all without the requirement for physical cooling. Published by the American Physical Society 2024

Environmentally robust all-polarization-maintaining random fiber laser of a cylindrical vector beam.

Random lasers with vector modes have garnered widespread attention due to their unique polarization and phase properties and the absence of cavity-defined longitudinal modes. In this work, we propose and demonstrate an all-polarization-maintaining (PM) random fiber laser (RFL) based on a half-open cavity that can simultaneously generate linearly polarized fundamental modes and higher-order modes. Then a cylindrical vector beam (CVB) of azimuthal polarization is generated by the mode superposition method with mode purity exceeding 93.4%. The mode conversion process is realized with a homemade long-period fiber grating and a fiber Bragg grating based on a PM few-mode (FM) fiber. The proposed compact and simple all-PM random laser is capable of generating a CVB without polarization controllers; thus, the environmental stability and self-starting ability will be greatly improved. This laser scheme will be beneficial for the design of vector mode random lasers and is expected to find diverse applications in modal division multiplexing systems, time-domain ghost imaging, and secure communication.

Mamyshev oscillation self-starting mode-locked fiber laser based on a self-feedback amplifying sub-cavity.

The Mamyshev oscillator (MO) boasts unparalleled modulation depth advantages in establishing mode-locking. However, this also significantly inhibits the self-starting of mode-locking. This Letter addresses the issue by constructing a self-feedback mechanism for regenerative oscillation. By amplifying noise cycles during the initial pumping phase to introduce periodic fluctuations in light intensity, we successfully achieve self-starting mode-locking at 1550 nm in an MO with a single gain arm structure at the pump power threshold of 76 mW. This self-starting mode-locking mechanism based on self-feedback sub-cavity amplification demonstrates excellent stability and repeatability in a single-arm MO structure. It provides what we believe to be a new approach for developing simple, reliable, and high repetition rate mode-locked lasers.

Open simple prostatectomy in the last three decades: results of a meta-analysis.

Open simple prostatectomy (OSP) has been a cornerstone in treating large prostate volumes (> 80ml) in benign prostatic hyperplasia (BPH). With evolving minimally invasive procedures like minimally invasive simple prostatectomy (MISP) and laser enucleation, the role of OSP needs contemporary evaluation. This way, we assessed the efficacy and safety of OSP to understand its current standing in the treatment of BPH, especially in comparison with newer surgical modalities. A comprehensive search of MEDLINE, Cochrane and EMBASE was conducted to include randomized controlled trials (RCTs) comparing OSP with other treatments for BPH from 1993 to 2023. A total of 10 RCTs were included in the meta-analysis. Data on various outcomes including IPSS, Qmax, PVR, quality of life, perioperative factors, and postoperative complications were analysed. Our meta-analysis, covering 557 patients, confirms OSP's significant improvement in voiding symptoms and objective voiding metrics. However, it also reveals a higher incidence of postoperative complications, such as bleeding and transfusion requirements. The study found moderate to high heterogeneity in perioperative outcomes, indicating variations in surgical techniques and postoperative care. OSP remains a reliable option with an easily accessible and effective approach for managing large prostates, despite advancements in minimally invasive surgeries. OSP continues to be a relevant surgical option for BPH in large prostates, offering significant symptom relief. However, the associated higher morbidity warrants careful patient selection and highlights the need for continued research into optimizing surgical techniques and improving outcomes.

Management of dermatosis papulosa nigra: a systematic review.

Dermatosis papulosa nigra (DPN) is a variant of seborrheic keratosis that typically presents as hyperpigmented pedunculated papules on the face, trunk, and/or back in those with skin of color. Although benign, the lesions can cause significant discomfort and distress. Management options are limited and often unaffordable, as treatment is elective in most cases. This study was undertaken to provide an updated summary of safe and efficacious treatments for DPN. Five databases were searched to identify full-text publications reporting on treatments and outcomes in adults with DPN. Seventeen publications met inclusion criteria and were included: six cohort studies, one randomized controlled trial, five case report studies, one case series, and four pilot studies. Treatment options included simple excision, curettage, electrodesiccation, cryotherapy, topicals, and laser therapies. These modalities varied in their documented outcomes and associated potential adverse effect profiles. Postinflammatory hyperpigmentation is a common adverse effect that often leads to patient dissatisfaction. It can be mitigated with topical treatments aimed at reducing local inflammation. Study limitations included small sample size in individual studies, lack of consistent reporting of Fitzpatrick skin type, and lack of comparison to the standard treatment of electrodesiccation or curettage. Ultimately, treatment should consider the patient's Fitzpatrick type, treatment area, associated costs, and potential adverse effects.

A comparative study on the efficacy of different treatment methods for preventing vocal cord adhesion after laser treatment for glottic cancer

Objective:Comparing the primary tumor control, vocal function recovery, postoperative adhesion rate and degree of adhesion in early glottic cancer involving the anterior commissure treated with CO₂ laser staged and lateral surgery, one-stage surgery combined with laryngeal stent placement, and simple CO₂ laser excision. Methods:This study focuses on 83 patients with T1-2N0M0 stage glottic squamous cell carcinoma involving the anterior commissure who underwent CO₂ laser treatment. The study was divided into three groups: Group A with 15 cases, treated with staged resection surgery; Group B with 18 cases, treated with one-stage surgery combined with the placement of a silicone laryngeal stent; and Group C with 50 cases, treated with simple CO₂ laser excision. The Voice Handicap Index-10（VHI-10）, the GRBAS auditory-perceptual assessment, and the maximum phonation time（MPT） were used to evaluate the vocal function of the patients before and six months after surgery. The degree of vocal cord adhesion was assessed using the Cohen classification of vocal cord adhesion. Statistical analysis was performed to determine the differences in each indicator before and after surgery, and the primary tumor control rates among the three groups. Results:Local recurrence occurred in 1 case each in Groups A and B, and in 4 cases in Group C, with no distant metastasis observed. Postoperative vocal cord adhesion of varying degrees occurred in a total of 77 cases, with an adhesion rate of 73.3%（11/15） in Group A, 88.9%（16/18） in Group B, and 100%（50/50） in Group C. The postoperative vocal cord adhesion rate and degree in Group C were significantly higher than in Groups A and B. The postoperative VHI-10 scores in all three groups were significantly increased compared to preoperative scores（P<0.05）, and when compared between groups postoperatively, Group C was significantly worse than Groups A and B （P<0.05）. The postoperative maximum phonation time（MPT） in Group C was significantly reduced compared to preoperative and was markedly shorter than that of Groups A and B postoperatively（P<0.05）. The postoperative grades of G（Grade） and R（roughness） in Group C were significantly higher than preoperatively, indicating a noticeable deterioration in voice quality, and were also significantly worse than those postoperatively in Groups A and B, with all differences（P<0.05）. Conclusion:For early glottic cancer involving the anterior commissure, choosing staged surgery or one-stage surgery combined with the placement of a silicone anterior commissure laryngeal stent were better than simple laser tumor excision in terms of secondary vocal cord adhesion and voice function preservation.

64 - The comparison of the efficacy and safety between robotic-assisted simple prostatectomy and laser enucleation for large benign prostate hyperplasia (> 80 gm): a systemic review and meta-analysis

64 - The comparison of the efficacy and safety between robotic-assisted simple prostatectomy and laser enucleation for large benign prostate hyperplasia (> 80 gm): a systemic review and meta-analysis

Low-temperature ppm-level H2S flexible gas sensor on the basis of Ag-modified ZnO

The development of flexible hydrogen sulfide (H2S) gas sensors capable of operating at low temperatures is crucial to meet the demand for wearable electronic devices. In this paper, silver-modified zinc oxide (Ag/ZnO) nanomaterials were synthesized using hydrothermal and alcoholic thermal methods. Flexible reduced graphene oxide (rGO) electrodes were fabricated on polyimide film using a simple laser direct writing method. The material was coated onto these rGO electrodes to create flexible gas sensors to measure low concentrations of H2S gas. Experimental results show that Ag nanoparticles modification enhanced the sensor's detection capabilities. All sensors demonstrated a response to 1 ppm H2S at 60 °C. The ZnO sensor with 7 % Ag showed a response for 1 ppm H2S of 1.99 at an optimum operating temperature of 120 °C. This response is 1.9 times higher than that of a pure ZnO sensor at 150 °C. Additionally, this sensor demonstrated excellent stability and selectivity, with a relatively low detection limit of 92 ppb. The Ag/ZnO sensor’s response mechanism to H2S was analyzed. Meanwhile, the charge transfer interactions among ZnO, Ag/ZnO, and H₂S were explained using density functional theory calculations. This study shows that the Ag/ZnO sensor has a simple flexible electrode preparation method, and the sensor's development process is cost-effective. Its sensing performance is also outstanding, especially with low operating temperature and detection limit. Therefore, it has promising applications in ppm-level H2S gas detection.

Superhydrophobic, Anti-Freezing and Multi-Cross-Linked Wearable Hydrogel Strain Sensor for Underwater Gesture Recognition.

Conductive hydrogel is considered to be one of the most potential sensing materials for wearable strain sensors. However, both the hydrophilicity of polymer chains and high water content severely inhibit the potential applications of hydrogel-based sensors in extreme conditions. In this study, a multicross-linked hydrogel was prepared by simultaneously introducing a double-network matrix, multiple conductive fillers, and free-moving ions, which can withstand an ultralow temperature below -80 °C. A superhydrophobic Ecoflex layer with a water contact angle of 159.1° was coated on the hydrogel using simple spraying and laser engraving methods. Additionally, the smart glove integrating five hydrogel strain sensors with a microprocessor was developed to recognize 12 types of diving gestures and synchronously transmit recognition results to smartphones. The superhydrophobic and antifreezing hydrogel strain sensor proposed in this study emerges promising potentials in wearable electronics, human-machine interfaces, and underwater applications.

Au/ZnO nanocomposites based on simple laser ablation method for water treatment

A binary heterostructure of Au/ZnO nanocomposite is prepared in a novel way based on successive pulsed laser ablation of the two targets in an aqueous solution with varied pulse time. The development of the method allows generating a noble metal (Au) and metal oxide (ZnO) one after one to produce a novel heterostructure with a tunable shell applicable as a catalytic degradable material. The nanocomposite samples are tested to study their optical, morphological, and structural properties. The photocatalytic degradation study demonstrates a significant decrease in the absorbance intensity of Rohdamin B (RhB) dye as the irradiation time increases. It indicates a reduction in dye concentration with a remarkable improvement in contact time. Besides, the degradation percentage against pH value is investigated. It reveals an increasing trend as the pH value rises with a maximum percentage at pH 10. The study is also concerned with the influence of the initial concentration of RhB dye on the degradation efficiency of the nanocomposite. Higher initial concentrations of the dye lead to a decrease in the degradation efficiency of the catalysts. Finally, the kinetic analysis of RhB photodegradation reveals that the Langmuir-Hinshelwood first-order kinetic model accurately describes RhB's adsorption onto the nanocomposites.

Generation of noise-like pulses in a linear-cavity Tm fiber mode-locked laser based on FMF saturable absorber

As a real saturable absorber (SA) based on the nonlinear multimode interference (NL-MMI) effect, the devices based on the few-mode fiber possess numerous exciting characteristics due to their all-fiber structure, straightforward manufacturing process. In this paper, by employing a SA with the SMF-FMF-SMF structure in a linear cavity, we demonstrate a stable mode-locked Tm-doped fiber laser. At the pump power of 1 W, a single noise-like pulse (NLP) with a pedestal pulse duration of 28 ps and coherent peak width of 0.77 ps is generated at a central wavelength of 1940 nm with a 3 dB bandwidth of 10.51 nm. The stable noise-like pulse can be sustained from the lasing pump threshold up to the maximum pump power of 2.2 W without experiencing pulse splitting. The experiment results in a peak average output power of 116 mW, along with a corresponding maximum pulse energy of 24.73 nJ at a repetition frequency of 4.69 MHz. The high stability of our fiber laser is confirmed by the signal-to-Noise Ratio (SNR) of 63 dB, and its enduring stability is additionally validated over an 8-hour period. The experimental findings suggest that the SMF-FMF-SMF structure has significant potential in the simple and robust all-fiber mode-locked lasers operating in the noise-like pulse regime.

Assembly of low-voltage driven co-production of hydrogen and sulfur via Ru nanoclusters on metal-sulfur coordination: Insights from DFT calculations

Herein, we propose a simple and rapid approach for synthesizing a CuS/Ru composite that serves as a bifunctional electrocatalyst to promote hydrogen production and concurrently convert sulfion into a value-added sulfur product. This composite comprises Ru nanoclusters supported on the CuS nanostructure, achieved through simple pulsed laser irradiation in liquid approach. The optimized CuS/Ru-30 electrocatalyst demonstrates remarkable bifunctional electrocatalytic activity, exhibiting a negligible working potential of 0.28 V (vs. RHE) for the anodic sulfion oxidation reaction (SOR) and a minimal overpotential of 182 mV for cathodic hydrogen evolution reaction (HER) to achieve 10 mA cm−2 of current density. Moreover, the CuS/Ru-30 electrocatalyst shows exceptional selectivity for converting sulfion into valuable sulfur during anodic oxidation reactions. Remarkably, in a two-electrode electrolyzer system utilizing CuS/Ru-30 as both the anode and cathode, the SOR + HER coupled water electrolysis system demands only 0.52 V to reach 10 mA cm−2, which is considerably lesser compared to the OER + HER coupled water electrolysis (1.85 V). The experimental results and density function theory (DFT) calculations reveal that the strong electron interaction between CuS and Ru nanoclusters generates a built-in electric field, greatly enhancing electron transfer efficiency. This significantly boosts the HER performance and facilitates the adsorption and production of sulfur intermediates. This study presents a rapid and simple strategy for synthesizing a dual-functional catalyst suitable for low-voltage hydrogen generation while facilitating the recovery of valuable sulfur sources.

Multibioinspired Hybrid Superwetting Surface for Efficient Fog Collection and Power Generation.

Obtaining water and renewable energy from the atmosphere provides a potential solution to the growing energy shortage. Leveraging the synergistic inspiration from desert beetles, cactus spines, and rice leaves, here, a multibioinspired hybrid wetting rod (HWR) is prepared through simple solution immersion and laser etching, which endows an efficient water collection from the atmosphere. Importantly, benefiting from the bionic asymmetric pattern design and the three-dimensional structure, the HWR possesses an omnidirectional fog collection with a rate of up to 23 g cm-2 h-1. We further show that the HWR could be combined with a droplet-based electricity generator to convert kinetic energy from falling droplets into electrical energy with a maximum output voltage of 200 V and a current of 2.47 μA to light up 28 LEDs. Collectively, this research provides a strategy for synchronous fog collection and power generation, which is promising for environmentally friendly energy production.

Generation of high-energy self-mode-locked pulses in a Tm-doped fiber laser

The incorporation of a material-based or artificial saturable absorber into a fiber laser cavity imposes a limitation on energy enhancement owing to its low damage threshold and high environmental sensitivity. To address this issue, one promising alternative approach is the utilization of the self-mode-locking technique. Here, we present a robust self-mode-locked Tm-doped fiber laser with high pulse energy emission. A simple and compact fiber laser structure is realized by utilizing a section of a Tm-doped fiber, serving both as a gain medium and a saturable absorber. Thus, the operational stability is enhanced, especially under high-energy conditions. Furthermore, the realization of high-energy pulses is accomplished through the integration of dispersion management technique. Experimental results reveal that the maximum single-pulse energy increases from 34.8 pJ to 120.2 nJ as the round-trip group delay dispersion decreases from −0.43 to −12.40 ps2. The proposed self-mode-locked Tm-doped fiber laser under high-energy operation exhibits remarkable performance. Our results provide a simple approach to obtaining a mid-infrared laser source with high pulse energy and hold significant potential for advancing high-energy laser systems.

Developing a simple and rapid method for cell-specific transcriptome analysis through laser microdissection: insights from citrus rind with broader implications

BackgroundWith the rapid development of single-cell sequencing technology, histological studies are no longer limited to conventional homogenized tissues. Laser microdissection enables the accurate isolation of specific tissues or cells, and when combined with next-generation sequencing, it can reveal important biological processes at the cellular level. However, traditional laser microdissection techniques have often been complicated and time-consuming, and the quality of the RNA extracted from the collected samples has been inconsistent, limiting follow-up studies. Therefore, an improved, simple, and efficient laser microdissection method is urgently needed.ResultsWe omitted the sample fixation and cryoprotectant addition steps. Instead, fresh samples were embedded in Optimal Cutting Temperature medium within 1.5 ml centrifuge tube caps, rapidly frozen with liquid nitrogen, and immediately subjected to cryosectioning. A series of section thicknesses of citrus rind were tested for RNA extraction, which showed that 18 μm thickness yielded the highest quality RNA. By shortening the dehydration time to one minute per ethanol gradient and omitting the tissue clearing step, the resulting efficient dehydration and preserved morphology ensured high-quality RNA extraction. We also propose a set of laser microdissection parameters by adjusting the laser power to optimal values, reducing the aperture size, and lowering the pulse frequency. Both the epidermal and subepidermal cells from the citrus rind were collected, and RNA extraction was completed within nine hours. Using this efficient method, the transcriptome sequencing of the isolated tissues generated high-quality data with average Q30 values and mapping rates exceeding 91%. Moreover, the transcriptome analysis revealed significant differences between the cell layers, further confirming the effectiveness of our isolation approach.ConclusionsWe developed a simple and rapid laser microdissection method and demonstrated its effectiveness through a study based on citrus rind, from which we generated high-quality transcriptomic data. This fast and efficient method of cell isolation, combined with transcriptome sequencing not only contributes to precise histological studies at the cellular level in citrus but also provides a promising approach for cell-specific transcriptome analysis in a broader range of other plant tissues.

Laser ablation and chemical vapor deposition to prepare a nanostructured PPy layer on the Ti surface

Abstract The deposition of polypyrrole (PPy) on a Ti surface is commonly employed to enhance the material’s properties for different applications such as supercapacitors, biomedicine, and corrosion resistance. Instead of complex or costly polymerization procedures for the PPy synthesis on the Ti metal surface, we utilized the effect of a simple and inexpensive laser ablation of the Ti surface in the open-air environment to prepare a hydrophilic TiO2 surface. In this condition, a thin PPy layer with remarkable nanostructures such as nanorings (∼80 nm) and nanotubes (∼245 nm) was deposited on a selective and desired pattern of ablated Ti areas through the chemical vapor deposition process using ferric chloride (FeCl3) solution as a pyrrole oxidizer. Raman and X-ray photoelectron spectroscopy (XPS) analyses confirmed the PPy formation on the Ti surface. The creation of these nanostructures was due to the micro/nanomorphology of the ablated Ti substrate. Water contact angle (WCA) measurements indicated the hydrophobic behavior of the PPy/Ti surface by the aging effect after 24 weeks with the change of WCA from 20° to 116°. The change in the surface chemical composition upon adsorption of airborne organic compounds with the long-term storage of PPy/Ti surface in air was studied by the XPS test.

A Novel Cost-Effective Approach To Flow Visualization Using Particle Streak Angles

Comprehending the complexity of pipe flow dynamics is important for a variety of sectors, including environmental, industrial, and engineering research. Conventional techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) have long been the heart of these kinds of investigations, but they are often quite expensive and complex. Our research offers a novel, affordable visualization method that aims to transform the way we examine and interpret flow dynamics in response to these challenges. Our method is developed to utilize a low-cost camera system with a simple laser setup to investigate fluid dynamics inside pipes. By introducing particles into the flow and manipulating the camera shutter speed in real-time under the laser, we created streaks capable of displaying complex flow patterns. We gathered precise information about streak angles using rigorous image processing, providing clarity in our insights into the flow dynamics of the particulate pipe flow. Notably, our strategy eliminates the need for expensive and sophisticated equipment while providing researchers and practitioners with a simple yet reliable alternative. The potential for improving our knowledge of pipe flow dynamics is shown by preliminary studies that demonstrate how well it captures dynamic flow characteristics. Our technique, which is easy to use and effective, promises fresh insights into fluid dynamics and opens up new avenues for pipe flow analysis, making it suitable for a broad spectrum of users.

Compact high-power 320-nm continuous-wave single-frequency laser based on power scaling of a diode-pumped Pr:LiYF4 ring laser at red.

Single-frequency (SF) lasers in the visible spectral region are usually obtained through an indirect method, i.e., frequency doubling of near-infrared SF lasers. In this work, we report on the direct generation of a high-power continuous-wave (CW) SF laser in red based on a diode-pumped Pr:LiYF4 (YLF) ring cavity technology. A maximum output power is scaled to 3.98 W at 640 nm with a linewidth of about 17.2 MHz and a power stability of 0.6%. Moreover, by inserting a LBO crystal into the ring cavity for intracavity frequency doubling of the 640 nm SF laser, we have also successfully demonstrated an ultraviolet (UV) SF laser at 320 nm, for the first time to the best of our knowledge, with a maximum power of 670 mW. This work provides a promising route for the development of simple, compact, and high-power SF lasers operating in visible and UV spectral regions.

High Performance Aqueous Zinc-Ion Batteries Developed by PANI Intercalation Strategy and Separator Engineering.

Aqueous zinc-ion batteries (ZIBs) have attracted burgeoning attention and emerged as prospective alternatives for scalable energy storage applications due to their unique merits such as high volumetric capacity, low cost, environmentally friendly, and reliable safety. Nevertheless, current ZIBs still suffer from some thorny issues, including low intrinsic electron conductivity, poor reversibility, zinc anode dendrites, and side reactions. Herein, conductive polyaniline (PANI) is intercalated as a pillar into the hydrated V2O5 (PAVO) to stabilize the structure of the cathode material. Meanwhile, graphene oxide (GO) was modified onto the glass fiber (GF) membrane through simple electrospinning and laser reduction methods to inhibit dendrite growth. As a result, the prepared cells present excellent electrochemical performance with enhanced specific capacity (362 mAh g-1 at 0.1 A g-1), significant rate capability (280 mAh g-1 at 10 A g-1), and admirable cycling stability (74% capacity retention after 4800 cycles at 5 A g-1). These findings provide key insights into the development of high-performance zinc-ion batteries.

Chitosan Oligosaccharide Laser Lithograph: A Facile Route to Porous Graphene Electrodes for Flexible On-Chip Microsupercapacitors.

In this study, a convenient chitosan oligosaccharide laser lithograph (COSLL) technology was developed to fabricate laser-induced graphene (LIG) electrodes and flexible on-chip microsupercapacitors (MSCs). With a simple one-step CO2 laser, the pyrolysis of a chitosan oligosaccharide (COS) and in situ welding of the generated LIGs to engineering plastic substrates are achieved simultaneously. The resulting LIG products display a hierarchical porous architecture, excellent electrical conductivity (6.3 Ω sq-1), and superhydrophilic properties, making them ideal electrode materials for MSCs. The pyrolysis-welding coupled mechanism is deeply discussed through cross-sectional analyses and finite element simulations. The MSCs prepared by COSLL exhibit considerable areal capacitance of over 4 mF cm-2, which is comparable to that of the polyimide-LIG-based counterpart. COSLL is also compatible with complementary metal-oxide-semiconductor (CMOS) and micro-electro-mechanical system (MEMS) processes, enabling the fabrication of LIG/Au MSCs with comparable areal capacitance and lower internal resistance. Furthermore, the as-prepared MSCs demonstrate excellent mechanical robustness, long-cycle capability, and ease of series-parallel integration, benefiting their practical application in various scenarios. With the use of eco-friendly biomass carbon source and convenient process flowchart, the COSLL emerges as an attractive method for the fabrication of flexible LIG on-chip MSCs and various other advanced LIG devices.