Applied Physics B最新文献

We propose and fabricate a monolithically integrated dual-mode semiconductor laser (DML) based on optical amplified feedback, where the adjustable optical self-injection feedback could induce dual-wavelength lasing, and the sub-millimeter total cavity length provides access to be microwave source. When keeping the injection current of semiconductor optical amplifier (SOA) be constant, inject different current for the segment of distributed feedback laser (DFB), we have achieved tunable microwave signal with different ranges of 10 GHz and 18 GHz respectively, which significantly simplifies the system configuration and reduces the footprint, power consumption and cost. Besides, through a special current injection scheme for the two-segment semiconductor laser, whole wavelength tuning with fixed wavelength spacing can also be realized. It provides a convenient and low-cost photonic solution for flexible and tunable microwave sources.

Refractive index (RI) is an important index to determine the composition of a substance, however, it is affected by temperature changes. Therefore, it is of great significance to design a sensor in which temperature variation will not affect the measurement of RI. In this paper, a double D-shaped photonic crystal fiber based on surface plasmon resonance (PCF-SPR) sensor is proposed to realize simultaneous and independent sensing of RI and temperature. The results show that the maximum sensitivity of the proposed sensor reaches 32,100 nm/RIU and 5.9 nm/℃ for RI and temperature, respectively. In addition, the changes of the air hole radius and the polishing depth will not cause the drift of the resonant wavelength. This advantage is conducive to fabricate a PCF-SPR sensor with high fault tolerance rate and lower production costs in practical process. The paper provides a reference for developing a high-sensitivity and multi-parameter measurement sensor used in water pollution monitoring and bio-sensing.

The present study demonstrates the suitability of the drop-casting technique for the determination of trace elements in liquids using laser induced breakdown spectroscopy (LIBS). In the present work, high-power laser shots are irradiated on the surface of a copper target to create a crater on it. Sample solutions containing trace metal elements, Na, Mg, Ca, Al, Fe and Zn are drop casted into the laser produced craters to obtain a homogeneous sample distribution. The sample is then ablated to form plasma, emissions from which are analysed to obtain a quantitative estimate of trace elements. The analytical accuracy of around 8% relative standard deviation (RSD) is achieved for the drop-casting of 3 µl of sample solution into the crater. Absolute detection limits of 0.06 mg/L for Na, 0.09 mg/L for Ca, 0.06 mg/L for Mg, 0.05 mg/L for Al, 0.23 mg/L for Fe and 0.11 mg/L for Zn are obtained. The proposed approach has been applied to estimate trace elements in liquid samples, including river water and multi-element standard solution. The present drop-casting LIBS technique has been validated using inductively coupled plasma optical emission spectroscopy (ICP-OES) technique and the results show a good resemblance.

Here, we investigate the structured superluminal and subluminal light propagation in the medium generated through a five-level atomic configuration controlled by a tiny probe and multiple of the control field. The absorption and dispersion are altered with the topological charges of control fields. The maxima and minima of absorption and corresponding normal/anomalous dispersion region are enhanced according to the (2ell) condition in the medium. The group index differs in the domain of (-15000le n_g le 17500) in the position ranges of (-1mu mle x,y le 1 mu m). The corresponding velocity of the envelope wave (v_{g}) is calculated by (c/n_g). The subluminal and superluminal maximum and minimum regions are also enhanced with the (2ell) condition in the medium. The modified work of this manuscript is useful for storage devices, imaging coding, and designing technology.

Alignment error significantly influences the fabrication quality of micro/nano structures in laser scanning heat-mode lithography systems. This paper presents an effective compensation strategy to address this issue. A laser heat-mode lithography system is established with a tightly focused objective lens and a grid scanning strategy, achieving a minimum grid size of 6 nm. The factors affecting alignment accuracy are then analyzed from the perspectives of the positioning error, galvanometer scanning distortion and coordinate system inclination. Following this, a compensation strategy is proposed, which adjusts the coordinate system of the dual-galvanometer to compensate alignment error. Experiments demonstrate the effectiveness, significantly reducing the maximum alignment error from 92.4 nm to 8.4 nm, improving alignment accuracy by approximately 91%. Furthermore, the fabrication of various structures with a minimum linewidth of 150 nm further confirms the excellent alignment performance of the system and demonstrates the advantages of laser heat-mode lithography. This work provides flexible compensation strategies for improving alignment accuracy in the dual-galvanometer laser scanning lithography system, paving the way for advancements in systems based on direct laser writing or other step-stitching lithography techniques.

This work presents an in-fiber plasmonic polarization filter using silicon hollow-core anti-resonant fiber (HC-ARF) with dual aluminum (Al) wires. The mature finite element tool is employed to conduct optical property analysis for the proposed all-fiber filter. The simulation results show that with reasonable design of structural parameters, the central operating wavelength of this filter can be determined at the common communication window of 1.55 μm. When the Al wires are stimulated, the plasmonic mode and the y-polarized transmission mode satisfy the phase matching conditions, leading to the surface plasmon resonance (SPR) effect, a significant energy difference can be acquired in the x- and y-polarized directions at 1.55 μm. The 14 mm-long optical filter demonstrates a maximum crosstalk (CT) of 123.24 dB, and a wide bandwidth with CT greater than 20 dB of 410 nm, ranging from 1.39 μm to 1.80 μm. Furthermore, the filter shows outstanding anti-bending capacity on the central wavelength and a high quadratic fitting relationship of 0.9938 between the bending radius and the central CT intensity. Additionally, it also has high manufacture feasibility. It is reasonable to believe that this in-fiber photonic filter can exert a crucial role in optical communication, sensing detection, signal modulation, and other domains.

For the first time, we realized 360 nm ultraviolet (UV) pulse laser by intracavity frequency doubling of a diode-pumped Q-switched Pr: YLF laser. An acousto-optic modulator was used as the active Q-switcher, and a BiB₃O₆ (BiBO) crystal served as the frequency doubler. A Q-switched laser was successfully obtained at a repetition frequency of 20 kHz, demonstrating excellent performance. Its maximum average output power reached 1.01 W, the maximum single-pulse energy was 50.5 µJ, the minimum pulse duration was merely 30 ns, and the maximum peak power was as high as 1.68 kW. When the repetition frequency was adjusted to 50 kHz, and the absorbed pump power of the 360 nm laser was 6.6 W, this laser’s maximum average output power climbed to 1.36 W, with a corresponding optical conversion efficiency of 20.6%. This novel UV laser is promising to be applied to many fields, such as environmental detection, THz wave generation, spectral analysis, microscopic imaging, and biotechnology.

Polarization detection is a crucial technology widely employed in infrared detection, image recognition, and space optical communication. Within the realm of infrared detection, it serves to enhance the detection of faint targets against complex backgrounds. Consequently, enhancing the performance of polarization devices has become one of the pivotal directions in quantum well infrared photodetectors (QWIPs) research. This paper proposes a novel circular polarization QWIPs inspired by stomatopods compound eye structure. By emulating the compound eye structure of the mantis shrimp, we integrate a top dielectric metasurface and a bottom one-dimensional metallic grating on QWIPs to achieve circular polarization detection. The dielectric metasurface, fabricated by etching heavily doped GaAs material, primarily functions as a quarter-wave plate, decomposing incident circularly polarized light into two orthogonally polarized linear components. The one-dimensional metallic grating at the bottom of device, acting as a linear polarizer, selectively excites surface plasmon polariton (SPP) modes, thereby distinguishing left-handed circularly polarized (LCP) light from right-handed circularly polarized (RCP) light. Finite-difference time-domain method was employed to calculate the total absorption spectrum of this integrated device. Under the LCP light incidence, the device exhibits a total absorption of 0.9 at the peak response wavelength of 7.8 μm, with a coupling efficiency of 3553%. Conversely, under RCP light incidence, the device demonstrates a total absorption of 0.1 at the same peak response wavelength, achieving a coupling efficiency of 95%. Furthermore, the device’s circular polarization extinction ratio reaches 37.4. This structure, achievable through quantum well focal plane array technology, represents a positive performing design for circular polarization QWIPs, contributing to enhancing target identification capabilities.

The sensitivity of coherent anti-Stokes Raman spectroscopy (CARS) is limited by the shot-noise from the probe fields used for stimulation and the non-resonant background noise. We have investigated the performance of the squeezing-enhanced version of CARS under homodyne detection and sum-intensity detection schemes, compared with the shot-noise limit (SNL) and quantum Cramér-Rao bound (QCRB). Our analysis shows homodyne detection performs better than sum-intensity and known single-intensity detection scheme results. It also provides a broader working range and shows more robustness against internal photon losses and remarkably improved performance in the gain-imbalanced configuration of SU(1,1) interferometer. As a result, we expect that our findings will be useful in quantum sensing and imaging techniques.

The thermal lens effect in a nonplanar ring oscillator laser was calculated using finite element analysis(FEA). The optical path difference (OPD) method shows that the thermal lens is significantly affected by strain and end face bulging, which is important for experimental considerations.