An all-silicon laser based on silicon nanocrystals with high optical gains

Silicon(Si)has become the most promising material for monolithic integrated photonic circuits with a wide range of scientific and industrial applications.A variety of Si photonic components,such as optical waveguides,optical modulators and photodetectors,have been successfully demonstrated,however,silicon lasers have not yet been achieved due to the low efficiency of Si emission.In 2000,Pavesi et al.[1]reported the first observation of

Optical manipulation in optofluidic microbubble resonators

An optical manipulation system based on optofiuidic microbubble resonators （MBR） is proposed. As the high-Q whispering gallery modes （WGMs） are excited in an MBR, the buildup of the field intensity inside the resonator is large enough to trap nanoscale particles. The optical gradient forces generated by the WGMs with different radial orders are investigated numeri- cally. The negative effect of the resonance detuning induced by the particles is taken into account to investigate the optical gradient forces exerting on the particles. By the stability analysis, the WGMs with high radial orders show a better trapping stability under Brownian motion since most of the optical fields reside within the water core.

Manipulating electromagnetic waves with metamaterials: Concept and microwave realizations

Our recent efforts in manipulating electromagnetic （EM） waves using metamaterials （MTMs） are reviewed with em- phasis on 1） manipulating wave polarization and transporting properties using homogeneous MTMs, 2） manipulating surface-wave properties using plasmonic MTMs, and 3） bridging propagating and surface waves using inhomogeneous meta-surfaces. For all these topics, we first illustrate the physical concepts and then present several typical practical real- izations and applications in the microwave regime.

Self Ordering of Nematic Liquid Crystal Molecules in HPDLC Bragg Gratings

Using the simple treatments of back refilling and subsequent annealing above the clear point of the liquid crystal,the self ordering of liquid crystal molecules is observed in a holographic polymer dispersed liquid crystal (HPDLC)Bragg grating without orientational layers or mechanical rubbing.Transmittance curve fitted anisotropy of the liquid crystal (△n) is in good agreement with its nominal value.

Improving the performance of crystalline Si solar cell by high-pressure hydrogenation

We report an approach of high-pressure hydrogenation to improve the performance of crystalline Si(c-Si) solar cells.As-received p-type c-Si wafer-based PN junctions were subjected to high-pressure(2.5 MPa) hydrogen atmosphere at 200 ℃,followed by evaporating antireflection layers,passivation layers,and front and rear electrodes.The efficiency of the so prepared c-Si solar cell was found to increase evidently after high-pressure hydrogenation,with a maximal enhancement of 10%.The incorporation of hydrogen by Si solar cells was identified,and hydrogen passivation of dangling bonds in Si was confirmed.Compared to the regular approach of hydrogen plasma passivation,the approach of high-pressure hydrogenation reported here needs no post-hydrogenation treatment,and can be more convenient and efficient to use in improving the performances of the c-Si and other solar cells.

Magnetic anisotropy manipulation and interfacial coupling in Sm_(3)Fe_(5)O_(12)films and CoFe/Sm_(3)Fe_(5)O_(12)heterostructures

The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd_(3)Ga_(5)O_(12)substrates from(111)to(001),the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane.Similar results can also be obtained in the films on Gd_(3)Ga_(5)O_(12)substrates,which identifies the universality of such orientation-induced magnetic anisotropy switching.Additionally,the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique.It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films.These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.

Achieving high-responsivity near-infrared detection at room temperature by nano-Schottky junction arrays via a black silicon/platinum contact approach

A room temperature sub-bandgap near-infrared (λ> 1100 nm) Si photodetector with high responsivity achieved. The Si photodetector features black Si made by wet etching Si (100),Si/PtSi nano-Schottky junctio arrays made from black Si/Pt contacts,and chemical and field-effect passivation of black Si. Responsivities a147.6,292.8,and 478.2 m A/W at reverse voltages of-1.0,-1.5,and-2.0 V for 1550 nm light,respectively,wit corresponding specific detectivities being 9.79×10^(8),1.88×109,and 2.97×10^(9)cm·Hz^(1∕2)∕W. This work dem onstrates a practical room temperature sub-bandgap near-infrared Si photodetector that can be made in a faci and large-scale manner.

Abnormal behaviors of Goos–Hänchenshift in hyperbolic metamaterials madeof aluminum zinc oxide materials

In this paper,the Goos–Hänchen shift(GHS)at the interface between air and the aluminum zinc oxide(AZO)/ZnO hyperbolic metamaterial(AZO-HMM)is theoretically examined.The results herein show that AZO-HMM can enhance the GHS at the interface to a value at 3 orders of the incident wavelength under special conditions,which is much larger than conventional GHS values.Moreover,the GHS can be tuned to be negative or positive by changing the incident wavelength or the volume fraction of AZO.

Regulation of the magnetic behavior by adjusting oxygen stoichiometry in ZrO_x film

The mechanism of ferromagnetic ordering in ZrOx film is investigated by both experimental observation and theoretical calculation.Magnetic measurements reveal that the magnetic properties can be adjusted from diamagnetism to ferromagnetism by varying the oxygen stoichiometry.We find that oxygen-rich defects can be responsible for the observed magnetic properties by taking the measurements of x-ray photoelectron spectroscopy and room temperature photoluminescence spectra.Density functional theory calculations further confirm that the ferromagnetic order is mainly driven by the exchange interaction between the oxygen antisites and the neighboring anion atoms.

Role of oxygen defects in inducing the blue photoluminescence of zinc oxide films deposited by magnetron sputtering

A number of zinc oxide（Zn O） films are deposited on silicon substrates using the magnetron sputtering method.After undergoing thermal treatment under different conditions, those films exhibit hexagonal wurtzite structures and different photoluminescent characteristics. Besides the notable ultraviolet emission, which is related to the free exciton effect, a distinct blue fluorescence around 475 nm is found in some special samples.The blue photoluminescence emission of the Zn O film is believed to be caused by oxygen vacancies.