Splicing loss and Fresnel reflection between a conventional fiber and a photonic crystal fiber can be minimized by reducing the air-hole diameter at the splicing point and taper slope.
Accurate prediction of the lifetime of a plasma ash melting furnace is essential for planning the timely repairs of it, as well as improving its design and operation. In this study, we took account of the slag temperature, the basicity of the ash and the ash feeding ratio to estimate the wear rate of the refractory material based on the mechanism of diffusion of SiO32- in the slag. The experiment using an electric furnace indicated clear relationship among the refractory wear, the slag temperature and the basicity of ash. The relationship between the refractory wear and the ash feeding ratio was found based on the data obtained from the furnace under commercial operation. The validity of this estimation method is demonstrated because the estimated amount of the refractory wear agreed well with the amount of the refractory wear measured in the plasma ash melting furnace after three month operation.
A non-destructive testing technique for a crack existing randomly on a ferrite surface has been developed. Wher the sample is immersed into the volatile solvent, the solvent penetrates into the crack. The surface of sampl? becomes dry quickly, however the solvent remains in the crack and evaporates slowly. The crack is detected independently its position by detecting the evaporating gas from the crack. A FID (flame ionization detector) iE used to detect the extremely thin solvent gas. The optimum treatments from immersion treatment to sealing treatment are studied using several samples with the crack width from 0.003 mm to 0.06 mm. A lot of cracks ar? tested using the experimental apparatus. Experimental results show that a linear relationship is established between crack width and S/N ratio, and the detectable crack length varies inversely with the crack width, fot example in case the surface area is 250 mm2, the minimum detectable length with crack width 0.05 mm is 0.3 mm and that with 0.003 mm is 1.4 mm.
It is desirable to control the mode states of a laser to stabilize it under the influence of environmental factors as well as to tailor the laser beam. Here, we demonstrate mixed-mode-state control in a photonic crystal surface-emitting laser at the chip level by leveraging the mechanism of mutual injection locking via dynamic control of the current injection distribution. We also demonstrate smart control, in which deep learning is applied to accurately predict the current injection distribution required to achieve a targeted beam pattern owing to manipulation of the mixed-mode state, and vice versa. These results could enable smart laser sources essential for advanced laser processing and additive manufacturing applications.
Recently, high-speed searching for the most similar reference data out of the database is needed for data compression, image recognition, network control, and others. However, it takes much time to search for data with software, or hardware using conventional memory. Associative memory has been developed as a high-speed searching device. In this paper, we propose a minimum Hamming distance search associative memory using neuron CMOS inverters. The proposed associative memory is less affected by initial charge and a change of threshold voltage of neuron MOS transistors than conventional neuron CMOS circuits. The proposed circuit also makes searching speed higher by using fully parallel processing. We confirmed that the proposed circuit can be realized expected results by simulation, and experiment using test chip.
Abstract We introduce multijunction active layers, featuring a stack of alternating active layers and tunnel junctions, to PCSELs to increase their slope efficiency, which is vital for various applications including laser processing and LiDAR. First, we design a multijunction PCSEL that avoids optical absorption in the heavily-doped tunnel junctions while allowing sufficient optical gain and resonance effects in the active and photonic crystal layers. Next, we fabricate a 3-mm-diameter two-junction PCSEL, achieving a slope efficiency of 1.58 W/A, which is over twice as high as that of conventional single-junction PCSELs, and a record-high peak output power of 1.8 kW for PCSELs.
Photonic-crystal surface-emitting lasers (PCSELs) are capable of single-mode, high-power lasing over a large resonator area owing to two-dimensional resonance at a singularity point of the photonic band structure. Since the number of photons in the lasing mode in PCSELs are much larger than those in conventional semiconductor lasers, PCSELs are in principle suitable for coherent operation with a narrow spectral linewidth. In this paper, we numerically and experimentally investigate intrinsic spectral linewidths of 1-mm-diameter PCSELs under continuous-wave (CW) operation, and we demonstrate CW operation with 1-kHz-class intrinsic linewidths and 5-W-class output power.
