The initial laser operation on the 4I11/24I13/2 transition of erbium-doped disordered calcium lithium niobium gallium garnet (CLNGG) crystals, emitting broadband mid-infrared light, is documented here, to the best of our knowledge. A continuous-wave laser, a 414at.% ErCLNGG type, emitted 292mW at 280m, demonstrating a slope efficiency of 233% and requiring a laser threshold of 209mW. In the CLNGG system, the spectral bands of Er³⁺ ions exhibit inhomogeneous broadening (SE= 17910–21 cm⁻² at 279 m; emission bandwidth 275 nm). This is accompanied by a high luminescence branching ratio (179%) for the ⁴I₁₁/₂ to ⁴I₁₃/₂ transition, and a favourable ratio of ⁴I₁₁/₂ and ⁴I₁₃/₂ lifetimes (0.34 ms and 1.17 ms respectively), for 414 at.% Er³⁺. The Er3+ levels were as follows, respectively.
A single-frequency erbium-doped fiber laser, operating at 16088 nm, has been realized using a home-built, highly erbium-doped silica fiber as its gain medium. Single-frequency laser operation is achieved by combining a ring cavity with a fiber saturable absorber element within the laser's configuration. In the laser linewidth measurements, a value below 447Hz was recorded, alongside an optical signal-to-noise ratio exceeding 70dB. The laser's performance showcased exceptional stability, with no instances of mode-hopping detected during the one-hour observation. The 45-minute monitoring period indicated a wavelength fluctuation of 0.0002 nm and a power fluctuation of less than 0.009 dB. Currently the highest power, as we know, obtained directly from a single-frequency erbium-doped silica fiber cavity laser, exceeding 16m, delivers over 14mW with a 53% slope efficiency.
Optical metasurfaces are shown to host quasi-bound states in the continuum (q-BICs), which are responsible for specific radiation polarization patterns. In this study, we investigated the correlation between the radiation polarization state of a q-BIC and the polarization state of the emergent wave, and developed a theoretical model for a perfectly linear polarization wave generator managed by the q-BIC. The proposed q-BIC exhibits x-polarization, and the introduction of additional resonance at the q-BIC frequency completely eliminates the y co-polarized output wave. At long last, a transmission wave precisely x-polarized, exhibiting exceptionally low background scattering, has been produced; its polarization state is not contingent upon the incident polarization. This device effectively generates narrowband linearly polarized waves from unpolarized sources, and it further enables polarization-sensitive high-performance spatial filtering capabilities.
Within this investigation, pulse compression, facilitated by a helium-assisted, two-stage solid thin plate apparatus, results in the production of 85J, 55fs pulses encompassing wavelengths between 350nm and 500nm. The main pulse contains 96% of the energy. Based on our current knowledge, these are the highest-energy sub-6fs blue pulses documented. Subsequently, in the process of spectral broadening, we witness a heightened vulnerability of solid thin plates to blue pulses in vacuum environments compared to gas-filled ones at comparable field intensities. Helium, characterized by its extraordinarily high ionization energy and exceedingly low material dispersion, is selected for the fabrication of a gas-filled environment. As a result, damage to solid thin plates is negated, and the production of high-energy, clean pulses is attainable with only two commercially available chirped mirrors contained within a chamber. Subsequently, the power output displays consistent stability, experiencing only 0.39% root mean square (RMS) fluctuations over one hour. We anticipate that the use of few-cycle blue pulses, centered around a hundred joules in energy, will create many new applications within this spectral region, especially those requiring ultrafast and high-intensity fields.
Improving the visualization and identification of functional micro/nano structures for information encryption and intelligent sensing applications is a significant potential benefit offered by structural color (SC). Although this is the case, the dual task of directly writing SCs at micro/nano scales and inducing color changes in response to external stimuli remains a substantial challenge. Direct laser printing of woodpile structures (WSs) was achieved using femtosecond laser two-photon polymerization (fs-TPP), producing structures with noticeable structural characteristics (SCs) evident under an optical microscope. Following the event, we executed the modification of SCs through the movement of WSs across varied mediums. Furthermore, a methodical study was conducted on how laser power, structural parameters, and mediums affect superconductive components (SCs), along with the use of the finite-difference time-domain (FDTD) method for a deeper understanding of the mechanism of SCs. selleck chemical In the end, we successfully unlocked the reversible encryption and decryption of specific data. This finding exhibits broad application possibilities in the areas of smart sensing, anti-counterfeiting identification, and high-performance photonic devices.
We, to the best of our knowledge, present the first demonstration of sampling fiber spatial modes using two-dimensional linear optics. Coherent sampling of the images of fiber cross-sections, stimulated by LP01 or LP11 modes, occurs on a two-dimensional photodetector array through local pulses with a uniform spatial distribution. Accordingly, the fiber mode's spatiotemporal complex amplitude is observed with a time resolution of only a few picoseconds utilizing electronic equipment with a bandwidth confined to a few MHz. Ultrafast and direct observation of vector spatial modes enables a precise and wideband characterization of the space-division multiplexing fiber's characteristics, resolving temporal features in detail.
Using a 266nm pulsed laser and the phase mask method, we demonstrate the fabrication of fiber Bragg gratings in PMMA-based polymer optical fibers (POFs) possessing a diphenyl disulfide (DPDS)-doped core. The process of inscription on the gratings utilized pulse energies varying between 22 mJ and 27 mJ. Upon exposure to 18 pulses of light, the grating exhibited a reflectivity of 91%. The as-fabricated gratings, despite their decay, experienced a resurgence in reflectivity, reaching as high as 98% following a post-annealing treatment at 80°C for 24 hours. This method of producing highly reflective gratings is applicable to the manufacture of high-quality, tilted fiber Bragg gratings (TFBGs) in polymer optical fibers (POFs) for biochemical analysis.
While many advanced strategies can flexibly control the group velocity of space-time wave packets (STWPs) and light bullets in free space, this control is limited to the longitudinal component of the group velocity. Within this work, a computational model, structured according to the principles of catastrophe theory, is formulated to enable the creation of STWPs capable of coping with both arbitrary transverse and longitudinal accelerations. We focus on the Pearcey-Gauss spatial transformation wave packet, which, being attenuation-free, contributes novel non-diffracting spatial transformation wave packets to the existing family. selleck chemical This project holds promise for driving the evolution of space-time structured light fields.
Excessive heat accumulation obstructs semiconductor lasers from operating at their full potential. This problem can be tackled by incorporating a III-V laser stack onto non-native substrate materials that have high thermal conductivity. III-V quantum dot lasers, heterogeneously integrated onto silicon carbide (SiC) substrates, exhibit high-temperature stability in our demonstration. A relatively temperature-insensitive operation of a large T0, at 221K, happens near room temperature. Lasing is maintained up to a temperature of 105°C. A unique and ideal platform for the monolithic integration of optoelectronics, quantum technologies, and nonlinear photonics is the SiC structure.
The non-invasive visualization of nanoscale subcellular structures is achieved using structured illumination microscopy (SIM). Consequently, improving the speed of imaging is hampered by the difficulties in image acquisition and reconstruction. A method is proposed to accelerate SIM imaging, utilizing spatial remodulation coupled with Fourier domain filtering based on measured illumination patterns. selleck chemical Using a standard nine-frame SIM modality, this method allows for high-speed, high-quality imaging of dense subcellular structures without the computational burden of pattern phase estimation. Seven-frame SIM reconstruction and supplementary hardware acceleration augment the imaging speed offered by our methodology. Our method's applicability further encompasses various spatially uncorrelated illumination schemes, such as distorted sinusoidal, multifocal, and speckle patterns.
During the diffusion of dihydrogen (H2) gas into a Panda-type polarization-maintaining optical fiber, the transmission spectrum of the fiber loop mirror interferometer is continuously assessed. Variations in birefringence are gauged by the wavelength shift detected in the interferometer spectrum during the insertion of a PM fiber into a gas chamber containing hydrogen, with concentrations between 15 and 35 volume percent, at 75 bar and 70 degrees Celsius. The birefringence variation, as measured, correlated with simulations of H2 diffusion into the fiber, showing a decrease of -42510-8 per molm-3 of H2 concentration inside the fiber. A minimum variation of -9910-8 was observed for 0031 molm-1 of H2 dissolved in the single-mode silica fiber (15 vol.%). H2 migration within the PM fiber modifies its strain state, leading to altered birefringence, a factor that could compromise the operation of fiber-based devices or enhance their sensitivity to hydrogen gas.
Cutting-edge image-free sensing techniques have achieved impressive performance in a range of vision-related tasks. However, image-independent methodologies are not yet equipped to acquire all the necessary data – the category, location, and size of all objects – in a singular operation. This letter details a novel, image-free, single-pixel object detection (SPOD) method.