We experimentally demonstrate an optically‐pumped III‐V/Si vertical‐cavity laser with lateral emission into a silicon waveguide. This on‐chip hybrid laser comprises a distributed Bragg reflector, a III‐V active layer, and a high‐contrast grating reflector, which simultaneously funnels light into the waveguide integrated with the laser. This laser has the advantages of long‐wavelength vertical‐cavity surface‐emitting lasers, such as low threshold and high side‐mode suppression ratio, while allowing integration with silicon photonic circuits, and is fabricated using CMOS compatible processes. It has the potential for ultrahigh‐speed operation beyond 100 Gbit/s and features a novel mechanism for transverse mode control.
The chaotic behaviour exhibited by a typical ferroresonant circuit
in a neutral grounding system is investigated in this paper. In most
earlier ferroresonance studies the core loss of the power transformer
was neglected or represented by a linear resistance. However, this is
not always true. In this paper the core loss of the power transformer is
modelled by a third order series in voltage and the magnetization
characteristics of the transformer are modelled by an 11th order two-term
polynomial. Extensive simulations are carried out to analyse the
effect of nonlinear core loss on transformer ferroresonance. A
detailed analysis of simulation results demonstrates that, with the
nonlinear core loss model used, the onset of chaos appears at a
larger source voltage and the transient duration is shorter. 相似文献
Columnar grains can lead to detrimental surface ridging and an inhomogeneous microstructure, although their {1 0 0}〈0 vw〉 texture is considered desirable due to their good magnetic properties in non-oriented silicon steel. Based on the hereditary tendency of {1 0 0}〈0 vw〉 texture, the effects of lubrication and heating rate on texture and on final magnetic properties were investigated using a cast slab containing 100% columnar grains. Hot rolling with lubrication, normalization at low heating rate, two-stage cold rolling, and final annealing at 1000 °C helped achieve high performance. As a result, a new non-oriented silicon steel with high magnetic induction (B50=1.82 T) and low core loss (P1.5=2.35 W/kg) was prepared. The possibility of further performance optimization was also discussed. 相似文献
Laser cutting of nickel-based superalloy sheets, having wide applications in aircraft and rocket industries, is important from the quality of cut point of view. Keeping this in view, a hybrid approach of Taguchi method (TM) and principal component analysis (PCA) has been applied for multi-objective optimization (MOO) of pulsed Nd:YAG laser beam cutting (LBC) of nickel-based superalloy (SUPERNI 718) sheet to achieve better cut qualities within existing resources. The three-quality characteristics kerf width, kerf deviation (along the length of cut), and kerf taper have been considered for simultaneous optimization. The input parameters considered are assist gas pressure, pulse width, pulse frequency, and cutting speed. Initially, single-objective optimization has been performed using TM and then the signal-to-noise (S/N) ratios obtained from TM have been further used in PCA for multi-objective optimization. The results of MOO include the prediction of optimum input parameter level and their relative significance on multiple quality characteristics (MQC). The responses at predicted optimum parameter level are in good agreement with the results of confirmation experiments conducted for verification tests. 相似文献
