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In this study, we realize the high-power output of a single-mode 894 nm vertical-cavity surface-emitting laser (VCSEL) at high temperature. The effects of the dimensional parameters of oxide aperture and surface relief on the transverse mode and threshold gain of VCSEL were analyzed. Through collaborative optimization of the oxide aperture and relief, the VCSEL with 8 µm oxide aperture diameter and 5 µm surface relief inner diameter can operate at high temperature of 365 K with single-mode output power of 2.02 mW and side-mode suppression of 29.2 dB.

Developing integrable, nanoscale, and low-energy-consumption lasers is a crucial step toward on-chip optical communications and computing technologies. The strong exciton-photon interaction that emerged in monolayer transition metal dichalcogenides (TMDs) holds promise for engineering and integration. Herein, we prepare the MoSe2/microsphere cavities excitonic lasers by placing SiO2 microspheres on top of a monolayer MoSe2 film. By virtue of continuous-wave exciting MoSe2/microsphere whispering gallery mode (WGM) cavities, we realize multiple excitonic WGM lasing in the emission wavelength range of ∼750-875 nm at room temperature with tunable properties of free spectral range (FSR) and full width at half-maximum (fwhm) by varying the microsphere size. Theoretical calculations based on the finite element method (FEM) using COMSOL software were utilized to identify lasing modes and reveal the corresponding electric field distribution. These findings help to deepen fundamental understanding of excitonic WGM lasing and provide a promising research platform for integrable, scalable, and low-cost laser devices.

A series of compressively strained AlGaInAs quantum well (QW) structures with different annealing treatment durations at 170 °C were investigated by temperature-dependent photoluminescence (PL). An abnormal S-shaped behavior in emission energy and a non-monotone evolution in spectral band width were observed at low temperature. A significant negative linear correlation between full width at half maximum (FWHM) and emission energy at different test temperature was exhibited in samples with different heat treatment durations. The highly linear relation demonstrated that the dependencies and relationships between PL peak energy and FWHM vs temperature are consistent. The anomalous blue shift and concomitant narrowing of FWHM in AlGaInAs QW were affected by lattice strain fluctuations due to the difference of thermal expansion coefficients between adjacent layers and strong carriers’ localization at low temperature.

We characterize laser generation in an ultralong air cavity (several meters in length) using an optical-pumped semiconductor gain chip for laser wireless charging applications. The study realizes laser generation in an external air cavity with a length of 200 cm, for the first time, and achieves a maximum output laser power of more than 86.3 mW. Furthermore, the laser oscillation can be maintained even when the output mirror of laser is off-axis within 1.6 cm. Thus, a long external cavity laser would ease the alignment between the laser beam and charging terminal, making it suitable for laser wireless charging applications.

In this paper, the wavelength current tuning characteristics of high-temperature-operation single-mode vertical-cavity surface-emitting lasers (VCSELs) for chip-scale atomic sensing systems are studied. Excellent wavelength current tuning robustness is helpful to improve the stability of atomic sensing systems. By optimizing the size of the oxide aperture combined with surface relief mode control technology, the single-mode VCSEL with an 8 µm oxide aperture can achieve 2.02 mW output power at 355 K, and the wavelength current tuning coefficient is ∼ 0.25 n m / m A . This excellent wavelength current tuning robustness results from the low active current density and device heat generation due to the optimized oxide aperture size.

Transverse optical confinement in oxide-confined vertical-cavity surface-emitting lasers (VCSELs) crucially depends on thickness of oxide layer and its position relative to a standing wave. Modifying the structure reduces the overlap between the oxide layer and the standing wave as well as effective refractive index difference between core and cladding of the VCSEL that subsequently decreases of the number of transverse modes and increases the mode extension beyond oxide aperture. A 795 nm VCSEL is designed and fabricated with this concept. The proposed device achieves high single-mode operation of 4.1 mW at 80 °C, SMSR of 41.68 dB, and OPSR of 27.4 dB. VCSEL is applied in a nuclear magnetic resonance gyroscope (NMRG) system as pump source due to its excellent device performance and satisfactory test results are obtained.

This publisher’s note amends the author listing in Appl. Opt. 59, 8789 (2020)APOPAI0003-693510.1364/AO.402699.

Developing integrable, nanoscale, and low-energy-consumption lasers is a crucial step toward on-chip optical communications and computing technologies. The strong exciton-photon interaction that emerged in monolayer transition metal dichalcogenides (TMDs) holds promise for engineering and integration. Herein, we prepare the MoSe

In this paper, the influence of the epitaxial structure on distributed Bragg reflector (DBR) grating characteristics is studied by simulation analysis. Comparative analysis shows that the symmetrical epitaxial structure can achieve a lower threshold current and, thus, a higher power. Based on the simulated structure, a DBR laser based on a symmetric epitaxial structure was fabricated, and a single longitudinal mode laser output at ∼ 1060 n m was obtained. The maximum power was 104.5 mW, and the side mode suppression ratio (SMSR) is 43 dB.

A tunable external cavity diode laser (ECDL) with high side-mode suppression ratio (SMSR) is demonstrated. The ECDL is operated at both strong and weak feedback steady states with single longitudinal mode. Compared with the strong feedback mode, the SMSR of the weak feedback mode is significantly enhanced by rotating the grating along the axis of the incident beam, which changes the polarization orientation versus the grating grooves. The highest SMSR of the weak feedback mode is 54 dB at the injection current of 300 mA. The tunable range of the ECDL with weak feedback mode reaches 130.9 nm.

In this paper, a high-order distributed Bragg reflector (DBR) semiconductor laser operating at 1064 nm is demonstrated based on simulation analysis. To get optimal Bragg grating characteristics, four parameters of the Bragg grating were analyzed in detail. Forty-nine-order Bragg gratings were designed with a reflectivity of 6% and a FWHM of 3 nm, which can realize mode selection while lasing. The Bragg gratings were designed to maximize the use of light. Transmission of the rear laser facet is theoretically 0. This simulation result provides a simple and efficient DBR semiconductor laser scheme without cavity surface coating.

A transverse Bragg resonance (TBR) waveguide semiconductor laser with sampled grating is proposed and analyzed. The transverse phase shift in the middle of the grating is realized by shifting half of the sampling period, resulting in a good single transverse mode resonance. The characteristics such as the modal gain, the electric field distribution, the near and far field beam patterns are theoretically studied. Since the sampled grating is designed by combining a uniform basic grating with a micrometer scale sampling pattern, it can be easily fabricated by holographic exposure and conventional photolithography with low cost. Therefore, the proposed method would be beneficial to volume fabrication of wide-stripe high power semiconductor lasers.

In this paper, we demonstrate high power, dual-wavelength (dual-λ) lasing stemming from bimodal-sized InGaAs/GaAs quantum dots (QDs). The device exhibits simultaneous dual-λ lasing at 1015.2 nm and 1023.0 nm with total power of 165.6 mW at 700 mA under room temperature continuous wave (CW) mode. Gaussian fitting analyses of the electroluminescence (EL) spectrum attribute the excellent performance to independent carrier transitions from the first excited states of large dot ensemble (LD ES1) and small dot ensemble (SD ES1), respectively. This formation provides a new possibility to achieve high power dual-λ operation only using Fabry-Perot (FP) cavity, which is significant for compact size and low fabrication cost.

In this paper, a widely tunable external cavity diode laser (ECDL) with an ultra-high side mode suppression ratio (SMSR) was fabricated. Three configurations were constructed to investigate the relationship between the grating features and the SMSR. When a 1200 grooves/mm grating with a first order diffraction efficiency of 91% is utilized in the external-cavity laser system, a maximum SMSR of 65 dB can be achieved. In addition, the tunable range reaches 209.9 nm. The results show that the laser performance can be improved by proper high grating groove number and first-order diffraction efficiency.

In this paper, a tunable external cavity diode laser (ECDL) based on the first excited states of two independent quantum dot (QD) ensemble has been demonstrated. The device exhibits stabilized lasing with high-power of 120 mW. We attribute the excellent output characteristics of the QD ECDL to carrier radiation recombination in high energy states, which has higher degeneracy than low energy states and can accommodate more carriers. The linewidth of ECDL is less than 0.2 nm, which is also much narrower than most of QD ECDLs as reported. Preliminary discussion attributes the spectra feature to the lower QD density and independent carrier transitions. The tunable range is 28.9 nm (970.1–999 nm) and the wavelength shift with the injection current is 0.7 nm A−1.

Centranthera grandiflora, a kind of traditional Chinese medicinal materials in Yunnan Province, has very high medicinal value. However, constant expansion of the plantation has resulted in worsening root diseases, an obstacle of continuous cropping. From 2018 to 2019, the author investigated the parasitic nematodes in the rhizosphere of Centranthera grandiflora in Pingbian County, Yunnan province, and identified them according to their morphological characteristics. The results showed that there were two kinds of parasitic nematodes harmful to Centranthera grandiflora root in Pingbian County, Yunnan: Tylenchorhynchus capitatus Allen, 1955 and Helicotylenchus dihystera (Cobb, 1893) sher, 1961.

In this work, a high-power and broadband superluminescent diode (SLD) is achieved utilizing bimodal-sized quantum dots (QDs) as active materials. The device exhibits a 3 dB bandwidth of 178.8 nm with output power of 1.3 mW under continuous-wave (CW) conditions. Preliminary discussion attributes the spectra behavior of the device to carrier transfer between small dot ensemble and large dot ensemble. Our result provides a new possibility to further broadening the spectral bandwidth and improving the CW output power of QD-SLDs.

Pomegranate (Punica granatum L.) is an important fruit crop in Yunnan Province, China. Black spot disease was observed on pomegranate fruits in Mengzi County. Symptomatic pomegranate fruits were collected during the autumn of 2012-2016, and used for the isolation of suspected fungus. On the basis of morphological characteristics and nucleotide homology, the isolate was identified as Cladosporium cladosporioides. Koch's postulates were performed. This is the first report of Cladosporium cladosporioides causing black spot disease of pomegranate in China.

An aluminum gallium indium arsenic (AlGaInAs) material system is indispensable as the active layer of diode lasers emitting at 1310 or 1550 nm, which are used in optical fiber communications. However, the course of the high-temperature instability of a quantum well structure, which is closely related to the diffusion of indium atoms, is still not clear due to the system&rsquo, s complexity. The diffusion process of indium atoms was simulated by thermal treatment, and the changes in the optical and structural properties of an AlGaInAs quantum well are investigated in this paper. Compressive strained Al0.07Ga0.22In0.71As quantum wells were treated at 170 &deg, C with different heat durations. A significant decrement of photoluminescence decay time was observed on the quantum well of a sample that was annealed after 4 h. The microscopic cathodoluminescent (CL) spectra of these quantum wells were measured by scanning electron microscope-cathodoluminescence (SEM-CL). The thermal treatment effect on quantum wells was characterized via CL emission peak wavelength and energy density distribution, which were obtained by spatially resolved cathodoluminescence. The defect area was clearly observed in the Al0.07Ga0.22In0.71As quantum wells layer after thermal treatment. CL emissions from the defect core have higher emission energy than those from the defect-free regions. The defect core distribution, which was associated with indium segregation gradient distribution, showed asymmetric character.

To explore the effects of insulin therapy on the expression of pigment epithelium-derived factor (PEDF) in adipocytes of type 2 diabetic mellitus (T2DM) in rats.A total of 22 newly diagnosed type 2 diabetics received a 2-week intensive insulin therapy. The levels of fasting plasma glucose (FPG), serum triglyceride and PEDF were measured before and after therapy. T2DM was induced by a high-fat diet and a low-dose streptozotocin (STZ). The Spraque-Dawley rats were divided randomly into diabetic, insulin treatment and gliclazide treatment groups. Another group with a chow diet was designated as normal controls. Differentiated 3T3-L1 adipocytes were then incubated with tumor necrosis factor-alpha (TNF-α) and (or) insulin for 24 h. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot were used to detect the expression of PEDF in adipose tissue or adipocytes. The PEDF levels in both sera and cell supernatant were measured by enzyme-linked immunosorbent assay (ELISA). Glucose uptake was detected after treatment of PEDF or anti-PEDF antibody simultaneously together with insulin in mature 3T3-L1 adipocytes.Insulin therapy decreased the serum levels of FPG and triglyceride of T2DM patients ((12.9 ± 2.8) vs (5.9 ± 1.4) mmol/L, (3.1 ± 1.8) vs (1.7 ± 0.8) mmol/L, P0.05) while the serum level of PEDF decreased significantly after therapy ((22.85 ± 5.73) vs (18.38 ± 5.28) µg/L, P0.05). Consistently the serum level of PEDF of diabetic rats was remarkably higher than that of normal controls and insulin-treated group ((28.6 ± 0.5) vs (25.4 ± 0.6) and (25.3 ± 0.6) µg/L, P0.05). And the elevated levels of PEDF, TNF-α mRNA and protein in adipose tissue (P0.05) could be reduced by insulin treatment (P0.05). However, no obvious change was detected in gliclazide treatment group. Further evidences suggested that TNF-α could induce more secretion and expression of PEDF in 3T3-L1 adipocyte while this effect became ameliorated by insulin treatment. Furthermore, decreased capacity of glucose uptake by PEDF might be reversed by anti-PEDF antibody in 3T3-L1 adipocytes (P0.05).Insulin can down-regulate the expression of PEDF in adipocytes of T2DM and improve the glucose uptake of adipocytes. It may be one of the mechanisms through which insulin therapy improves peripheral insulin resistance.

Early intensive insulin therapy improves insulin sensitivity in type 2 diabetic patients; while the underlying mechanism remains largely unknown. Pigment epithelium-derived factor (PEDF), an anti-angiogenic factor, is believed to be involved in the pathogenesis of insulin resistance. Here, we hypothesize that PEDF might be down regulated by insulin and then lead to the improved insulin resistance in type 2 diabetic patients during insulin therapy. We addressed this issue by investigating insulin regulation of PEDF expression in diabetic conditions. The results showed that serum PEDF was reduced by 15% in newly diagnosed type 2 diabetic patients after insulin therapy. In adipose tissue of diabetic Sprague-Dawley rats, PEDF expression was associated with TNF-α elevation and it could be decreased both in serum and in adipose tissue by insulin treatment. In adipocytes, PEDF was induced by TNF-α through activation of NF-κB. The response was inhibited by knockdown and enhanced by over expression of NF-κB p65. However, PEDF expression was indirectly, not directly, induced by NF-κB which promoted 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) expression in adipocytes. 11β-HSD1 is likely to stimulate PEDF expression through production of active form of glucocorticoids as dexamethasone induced PEDF expression in adipose tissue. Insulin inhibited PEDF by down-regulating 11β-HSD1 expression. The results suggest that PEDF activity is induced by inflammation and decreased by insulin through targeting 11β-HSD1/glucocorticoid pathway in adipose tissue of diabetic patients.