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We demonstrated a continuous intracavity diamond Raman laser operating by linear-cavity and V-cavity design. The diamond crystal as the Raman medium and Nd: YVO4 as the laser gain medium was utilized to achieve high beam quality Stokes output with narrow line width. By employing linear and V-shaped cavity, we achieved Stokes light outputs of 1.68 and 2.26 W, respectively. Compared to the linear cavity, the V-shaped cavity has a higher conversion efficiency of 11.07% and a narrower linewidth of 0.07 nm. Mechanism for linewidth of different cavity design and methods for further increasing power range and high quality are discussed.

This study reports new types of passive mode-locked Er-doped fiber laser (EDFL) based on a segment of doped fiber saturable absorber (DFSA) with Tm/Ho-doped fiber (THDF), Yb-doped fiber (YDF), and Er-doped fiber (EDF). By employing THDF-SA, a bright pulse sequence with a fundamental repetition rate of 17.86 MHz was obtained. In addition, various mode-locked output states, including dark pulses, dark–bright pulse pairs, bright–dark pulse pairs, and second-harmonic pulses, were obtained through polarization modulation and gain modulation, and the orthogonality of dark–bright pulses in both polarization directions was verified. Furthermore, using EDF-SA and YDF-SA, dark pulses and dark–bright pulses were obtained. A comparison of the three experiments revealed that THDF-SA effectively reduces the mode-locked threshold and improves the average output power. Compared with bright pulses, dark pulses offer several advantages such as resisting noise, increasing propagation speed, and suppressing nonlinear scattering (such as pulse-intrinsic Raman scattering); thus, the EDFL can find broad application in long-distance transmission, precision measurement, and other fields.

Diamond crystals have garnered significant attention for applications in photonics, owing to their characteristics of ultra-high thermal conductivity, extremely broad spectral transmission range, and high Raman gain coefficient. These characteristics are particularly advantageous for the development of high-power, multi-wavelength lasers. In this work, we utilize single crystal diamond as a Raman gain medium, for intracavity wavelength-conversion of emission from a side-pumped, electro-optically Q-switched Nd:YAG module. Cascaded Raman conversion is demonstrated and dual-wavelength, pulsed laser emission at wavelengths of 1.2 μm (first-Stokes wavelength) and 1.5 μm (second-Stokes wavelength) is achieved (with a maximum combined pulse energy of 6.19 mJ). The relative ratio of output energy at the two Stokes orders could be varied by tuning the characteristics of the output coupling mirror and the length of the laser resonator. When operating at maximum pump power, the pulse width of the second-Stokes field was approximately half that of the first-Stokes field (second-Stokes ∼10 ns, first-Stokes ∼18 ns), resulting in maximum peak powers of 174 kW (at 1.2 μm) and 220 kW (at 1.5 μm). To the best of our knowledge, this is the highest reported peak power generated from a dual-wavelength, intracavity diamond Raman laser. This work highlights the diversity and utility of diamond as an effective wavelength-conversion component in high-power lasers, and stands as the current state-of-the-art in high pulse-energy, high peak-power, multi-wavelength intracavity Raman lasers.

We present a numerical investigation of the bound-state pulse formation mechanism and evolutionary dynamics based on the pump strength and spectral filtering bandwidth in the all-fiber Mamyshev oscillator. Through the numerical simulation and analysis, the different mode-locked pulses’ (such as single pulses, bound-state pulses, and chaotic multi-pulses) regime transformation conditions are quantified. The results suggest that with an increase in the pump strength, the sub-pulse energy and output coupler of the Mamyshev oscillator show an inverse proportion trend, which plays an important role in increasing the number of sub-pulses in the bound-state pulses’ state. Furthermore, optimization schemes, such as adjusting the filter bandwidth and slowing down the accumulation of nonlinear effects, are proposed to achieve a high-energy pulse output in the Mamyshev oscillator.

Abstract Plants have to cope with the surrounding changing environmental stimuli to optimize their physiological and developmental response throughout their entire life cycle. Light and temperature are two critical environmental cues that fluctuate greatly during day-night cycles and seasonal changes. These two external signals coordinately control the plant growth and development. Distinct spectrum of light signals are perceived by a group of wavelength-specific photoreceptors in plants. PIFs and COP1-HY5 are two predominant signaling hubs that control the expression of a large number of light-responsive genes and subsequent light-mediated development in plants. In parallel, plants also transmit low or warm temperature signals to these two regulatory modules that precisely modulate the responsiveness of low or warm temperatures. The core component of circadian clock ELF3 integrates signals from light and warm temperatures to regulate physiological and developmental processes in plants. In this review, we summarize and discuss recent advances and progresses on PIFs-, COP1-HY5- and ELF3-mediated light, low or warm temperature signaling, and highlight emerging insights regarding the interactions between light and low or warm temperature signal transduction pathways in the control of plant growth.

A novel side-opening grapefruit fiber-based SPR sensor is designed to realize simultaneous measurement of refractive index (RI) and temperature. The open section of the grapefruit fiber is coated with a gold layer, which can support two main resonance peaks. The variations of RI and temperature can influence the coupling efficiency between core-guided mode and plasmon mode, thus lead to the two peaks shifts that can be used to determine the variations of RI and temperature. Simulation results demonstrate that the RI coefficients of Peak I and Peak II are 1400 nm/RIU and 226 nm/RIU, respectively. The temperature coefficients of Peak I and Peak II are 34 pm/°C and 527.2 pm/°C, respectively.

We propose a concept of surface plasmon resonance sensor based on double-sided polished microstructured optical fiber coated with graphene-on-silver layers. The silver films on the polishing planes are covered with multilayer graphene which can prevent the oxidation of silver and enhance the adsorption of biomolecules. The sensing performance of the proposed sensors with polishing planes angle of 0°, 60° and 120°, are investigated by using both wavelength and amplitude interrogations. Our numerical results demonstrate that increasing the size of the air hole in the core area can effectively improve the wavelength and maximum amplitude sensitivities. Moreover, growing number layer of graphene can increase wavelength sensitivity, whereas decrease the maximum amplitude sensitivity.

We demonstrate a sensitivity-tunable temperature SPR sensor based on side-opening grapefruit fiber. The opening sections of the fiber are coated with gold layer and then filled with a liquid mixture of ethanol and chloroform as the sensing medium. The variation of the temperature will lead to different coupling efficiencies between the core-guided mode and the plasmonic mode, and then resulting in the change of loss spectra of the fiber that will be detected. Simulation results indicate that the temperature sensitivity of the sensor is 19.9 nm/°C at 10°C when the volume fraction of ethanol in the mixture is 0.1. Moreover, by adjusting the volume fraction, the sensitivity of proposed sensor can achieve the upper limit for a certain temperature range without the excitation of higher order plasmonic modes.

We propose a concept of orthogonal-side polished microstructured optical fiber (MOF)-based surface plasmon resonance (SPR) sensor to implement the simultaneous sensing for two parameters. Two feasible structures, L-shaped MOF based and rectangular MOF based SPR sensors are investigated theoretically, which can support x- and y-polarized resonance peaks that can be used to measure and separate variations of the temperature and refractive index (RI). Our results show that the temperature coefficients (KTx and KTy) are 8 pm/°C and 6 pm/°C, and the RI coefficients (Knx and Kny) are 1470 nm/RIU and 1570 nm/RIU, for the L-shaped MOF-SPR sensor, while the KTx and the KTy are 10 pm/°C and 8 pm/°C, the Knx and Kny are 1460 nm/RIU and 1500 nm/RIU, for the rectangular MOF-based SPR sensor. Moreover, these coefficients can be further improved by choosing the appropriate structure parameters. The proposed SPR sensors with the advantages of simultaneously measuring two parameters and no need to be filled with the sensing media are expected to be more competitive in the MOF-based SPR sensor field.

Repetition rate-tunable single-longitudinal-mode (SLM) lasers are in wide demand for light detection and ranging. This study proposes an SLM acoustic-optical Q-switched Nd:YVO4 laser based on a short-cavity scheme. The laser system consists of a laser diode (LD) pump source, coupling optics, input mirror coupler (IC), Nd:YVO4 crystal, acousto-optic Q-switching system (AOQS), and output mirror coupler (OC). The mode selection is theoretically analyzed and confirmed from the experimental setup. The laser output obtains a 10 ns pulse duration, SLM with a linewidth of 279.43 MHz, and good stability that is maintained in the range of 1 to 4 kHz. The results demonstrate that the proposed method is a simple and robust source-laser scheme for high-power systems.

A method to accurately measure the linewidth of short laser pulses at a low repetition rate is demonstrated. Based on the principle of parallel plate equal inclination interference, the linewidth of a short-pulse laser with a low repetition rate is measured by using a Fabry-Pérot (F-P) etalon combined with a CMOS beam profiler. The center of the recorded interference pattern is precisely identified using Hough transformation, and a pixel rotation algorithm is applied to maximise the data collected, transforming two-dimensional image information into one-dimensional spectral information. This algorithm significantly increases the number of data points, improves the spectral resolution, and reduces the error caused by the size of the CMOS pixel size to less than 1 MHz. The influence of the transmission spectrum width (TSW) of the F-P etalon on the measurement results is analyzed, and we demonstrate a reduction in the error introduced by the TSW of the F-P etalon is through deconvolution. This further improves the measurement quality and provides a means by which etalons with a wide TSW can be applied to the measurement of the linewidth of lasers with low pulse energy.

A compact solid-state single-longitudinal-mode (SLM) Q-switched laser based on a compound cavity is demonstrated. SLM operation is achieved through the enhancement of mode competition (via manipulation of the effective reflectivity of the resonator mirrors and intracavity field accumulation time) and does not require the use of a feedback loop. In this work, SLM emission with a linewidth of 254.3 MHz is demonstrated, and a high SLM ratio of up to 99.6% is achieved. The laser operates at a repetition rate of 10 Hz, producing 10 ns pulses with a pulse energy of 14.81 mJ.

A narrow-linewidth laser with excellent temporal coherence is an important light source for microphysics, space detection, and high-precision measurement. An ultranarrow-linewidth output with a linewidth as narrow as subhertz has been generated with a theoretical coherence length over millions of kilometers. Traditional grating spectrum measurement technology has a wide wavelength scanning range and an extended dynamic range, but the spectral resolution can only reach the gigahertz level. The spectral resolution of a high-precision Fabry–Pérot interferometer can only reach the megahertz level. With the continuous improvement of laser coherence, the requirements for laser linewidth measurement technology are increasing, which also promotes the rapid development of narrow-linewidth lasers and their applications. In this article, narrow-linewidth measurement methods and their research progress are reviewed to provide a reference for researchers engaged in the development, measurement, and applications of narrow-linewidth lasers.

We proposed a compact experimental scheme for a low repetition rate, high-energy, nanosecond laser at 604 nm based on Pr: YLF crystal at room temperature. The thermal effect of Pr: YLF crystal was simulated, which demonstrated that high energy 604 nm laser line at room temperature can be generated with appropriate parameters such as crystal and the laser output coupling. Then a stable 604 nm orange laser pumped by a pulsed 444 nm optical parametric oscillator was developed experimentally. A high pulse energy of 63 μJ with 30 ns pulse duration at a repetition rate of 10 Hz was obtained. To the best of our knowledge, this is the first report of such a high-energy 604 nm laser using a gain switched pump source at room temperature.

Diamond has a broad spectral transmission range (>0.2 μm) and the largest Raman frequency shift (1,332 cm−1) among known Raman crystals. Hence, the diamond Raman laser has the potential to achieve lasing in the long-wave infrared (LWIR) range, which is difficult to reach via other crystalline lasers. Here, we report a new approach to achieve LWIR output using diamond Raman conversion and provide the corresponding analysis model and simulation results. The conversion efficiency is analyzed as function of the pump waist size, output-coupler transmission, and crystal length, at constant pump power. The maximum output power at which a diamond of relatively large size can be operated without damage is predicted. This study paves a way for high-power LWIR lasing in diamond.

Delayed self-heterodyne/homodyne measurements based on an unbalanced interferometer are the most used methods for measuring the linewidth of narrow-linewidth lasers. They typically require the service of a delay of six times (or greater) than the laser coherence time to guarantee the Lorentzian characteristics of the beat notes. Otherwise, the beat notes are displayed as a coherent envelope. The linewidth cannot be directly determined from the coherence envelope. However, measuring narrow linewidths using traditional methods introduces significant errors due to the 1/f frequency noise. Here, a short fiber-based linewidth measurement scheme was proposed, and the influence of the noise floor on the measurement of the laser linewidth using this scheme was studied theoretically and experimentally. The results showed that this solution and calibration process is capable of significantly improving the measurement accuracy of narrow linewidth.

Stimulated Raman scattering, as a third-order nonlinear effect, is an effective approach to expand the laser spectral region. To obtain a high power output of a Raman laser with a specific wavelength, novel Raman gain media and laser structures have been continuously studied, and in recent years, diamonds have received an increased interest from researchers owing to their extremely high Raman gain coefficient, high thermal conductivity, and wide transmission spectrum. Diamond Raman lasers (DRLs) have enabled the achievement of a laser input in the visible to the mid-infrared band. In particular, lasers with outputs in the 1.5 μm band have the characteristics of an atmospheric window and being eye-safe, which are critical for applications in the medical, distance measurement, radar, and other such domains. Consequently, researchers are constantly improving the methods to output a higher power laser at 1.5 μm, and the DRLs offer the potential to realize a high power and high beam quality in this band. This paper provides a review of the research status of eye-safe DRLs and suggests opportunities for future development and applications.

All-solid-state passively Q-switched lasers have advantages that include simple structure, high peak power, and short sub-nanosecond pulse width. Potentially, these lasers can be applied in multiple settings, such as in miniature light sources, laser medical treatment, remote sensing, and precision processing. Cr4+:YAG crystal is an ideal Q-switch material for all-solid-state passively Q-switched lasers owing to its high thermal conductivity, low saturation light intensity, and high damage threshold. This study summarizes the research progress on all-solid-state passively Q-switched lasers that use Cr4+:YAG crystal as a saturable absorber and discusses further prospects for the development and application of such lasers.

High-power lasers with high beam quality are widely used across applications such as advanced manufacturing, space exploration, high-energy physics, and defense. Lasers using crystalline gain media have advanced through large-sized crystals, which enable high power outputs by providing large gain volumes and flexible thermal management. However, population-inversion-based lasers remain constrained by energy storage, and the thermal properties of the gain material. Therefore, increasing the size of the gain medium does not fully address severe thermal effects or heat accumulation. As a result, continuous high-power lasing from such lasers with high-beam quality operation is challenging. Nonlinear optical conversion methods have gained attention as a solution, enabling high-power laser emission at wavelengths not directly accessible from gain media. Unlike inversion lasers, lasers based on nonlinear optical conversion avoids energy storage in the medium thus avoiding significant heating. Diamond, with its exceptional optical and thermal properties, including ultra-high Raman and Brillouin gains, large Raman frequency shift, and the highest thermal conductivity among crystalline materials, is a promising nonlinear gain medium. Millimeter-scale diamond crystals have been employed as nonlinear gain media to achieve laser output with peak power reaching megawatt level and continuous-wave power reaching kilowatt level, all while maintaining near-diffraction-limited beam quality. As diamond growth technologies mature, large high-quality diamonds for lasing are increasingly available. This perspective summarizes recent research progress on high-power diamond lasers and analyzes factors such as diamond size and quality that have limited their power scaling. It is anticipated that diamond-based lasers will open new frontiers in high-power laser technologies. In the near future, peak power at gigawatt level and continuous-wave power in the hundreds of kilowatts range are achievable utilizing only centimeter-scale diamond crystals.

Abstract Damage to renal tubular epithelial cells (RTECs) signaled the onset and progression of sepsis-associated acute kidney injury (SA-AKI). Recent research on mitochondria has revealed that mitophagy plays a crucial physiological role in alleviating injury to RTECs and it is suppressed progressively by the inflammation response in SA-AKI. However, the mechanism by which inflammation influences mitophagy remains poorly understood. We examined how macrophage migration inhibitory factor (MIF), a pro-inflammatory protein, influences the PINK1-Parkin pathway of mitophagy by studying protein–protein interactions when MIF was inhibited or overexpressed. Surprisingly, elevated levels of MIF were found to directly bind to PINK1, disrupting its interaction with Parkin. This interference hindered the recruitment of Parkin to mitochondria and impeded the initiation of mitophagy. Furthermore, this outcome led to significant apoptosis of RTECs, which could, however, be reversed by an MIF inhibitor ISO-1 and/or a new mitophagy activator T0467. These findings highlight the detrimental impact of MIF on renal damage through its disruption of the interaction between PINK1 and Parkin, and the therapeutic potential of ISO-1 and T0467 in mitigating SA-AKI. This study offers a fresh perspective on treating SA-AKI by targeting MIF and mitophagy.