多晶一体化大功率LED照明光源关键技术研究与产品开发

大功率LED技术是目前替代光源的重要形式，本文针对传统LED中存在的技术散热差、易老化、光源不均匀等弱点进行了改进和创新，从而形成了一种新型的大功率LED照明用光源，获得了较好的效果。

A new barium-containing alkali metal silicate fluoride NaBa3Si2O7F with deep-UV optical property

A new silicate fluoride,NaBa3 Si207 F,has been successfully synthesized by a high-temperature solution method.It crystallizes in the orthorhombic space group Cmcm(No.63).NaBa3 Si2 O7 F is the first barium-containing alkali metal silicate fluoride with the[NaO6]polyhedra,the[BaO8 F]polyhedra and isolated[Si2 O7]units.The optical characterizations indicate that NaBa3 Si2 O7 F possesses wide transparent window and available luminescence properties.To confirm the coordination surroundings of anionic groups and its thermostability,infrared spectroscopy and thermal behaviors were also analyzed,which proved the existence of tetrahedronly coordinated silicium atoms and the good stability of NaBa3 Si2 O7 F at high temperature.First-principles calculation was also implemented for better understanding the relationship between the structure of NaBa3 Si207 F and its property.Additionally,to further explore the structural novelty of NaBa3 Si2 O7 F,the comparison of the anionic structures was carried out in mixed alkali and alkaline-earth metal silicate fluorides.Interestingly,the result indicates the isolated[Si2 O7]dimer is rare among the above systems,which enriches the structural chemistry of silicate fluorides.

Multi-band design for one-dimensional phononic crystals

Periodic composites with band gaps that prevent the propagation of elastic waves in certain frequency ranges can be used to control waves for a variety of engineering applications. Although studies on the characteristics of these materials, which are called phononic crystals (PCs), have yielded a large number of positive results in recent years, there is still a lack of effective design methods. In this work, a multi-objective optimization approach based on the band gap mechanism and an intelligent algorithm is used to design a one-dimensional (1D) slab construction of PCs. The design aims to fit pre-determined bands by arranging the available materials properly. Obtained by analyzing the wave transmission in periodic layers, the objective functions are linked to the optimization program to obtain a proper solution set. The results of the numerical simulations demonstrate that without constructing complicated structures, the design method is able to produce PCs that overcome the limitations of two-component PCs and hence can feasibly and effectively achieve the design targets. The design approach presented in this paper can be extended to two-or three-dimensional systems and has great potential for the development of sound/ultrasound isolation structures, multiple band frequency filters, and other applications.

A compact dual-band bandpass filter based on porous silicon dual-microcavity of one-dimensional photonic crystal

We propose a compact dual-band bandpass filter(BPF)based on one-dimensional porous silicon(PS)photonic crystal by electrochemical etching.By inserting three periods of high and low reflective index layers in the center of porous silicon microcavity(PSM),two sharp resonant peaks appear in the high reflectivity stop band on both sides of the resonance wavelength.Through simulation and experiment,the physical mechanisms of the two resonance peaks and the resonance wavelength are also studied.It is found that the resonance wavelength can be tuned only by adjusting the effective optical thickness(EOT)of each PS layer,in which different resonance wavelengths have different widths between the two sharp resonance peaks.Besides,the analysis indicates that oxidization makes the blue shift become larger for high wavelength than that for low wavelength.Such a fabricated BPF based on PS dual-microcavity is easy to be fabricated and low cost,which benefits the application of integrated optical devices.