We demonstrate that the optical absorption is enhanced in small molecule organic solar cells by using a trapezoid grating structure. The enhanced absorption is mainly attributed to both waveguide modes and surface plasmon modes, which is simulated by using finite-difference time-domain method. The simulated results show that the surface plasmon along the semitransparent metallic Ag anode is excited by introducing the periodical trapezoid gratings, which induce the increase of high intensity field in the donor layer. Meanwhile, the waveguide modes result in a high intensity field in acceptor layer. The increase of field improves the absorption of organic solar cells significantly, which is demonstrated by simulating the electrical properties. The simulated results also show that the short-circuit current is increased by 31% in an optimized device, which is supported by the experimental measurement. Experimental result shows that the power conversion efficiency of the grating sample is increased by 7.7%.
Coherent anti-Stokes Raman scattering spectroscopy（CARS） is a well-known detecting tool in biosensing and nonlinear spectroscopy. It can provide a non-invasive alternative without the need for exogenous labels,while the enhancement factor for surface plasmon resonances（SPR） are extensively used to increase the local field close to the oscillators and which can obtain high enhancement. In this work, we investigate the enhancement factor of our structure for surface-enhanced coherent anti-Stokes Raman scattering. The absorption spectrum of the structure has been studied, a wide range of absorption has been realized. The enhancement can be as high as 10^（16） over standard CARS. Our design is very useful for improving the enhancement factor of surface-enhanced coherent anti-Stokes Raman scattering.
An ultra-compact variable optical attenuator based on slow light photonic crystal waveguide with thermo- optic effect is demonstrated. Along with power consumption of as low as 30.7 roW, a variable attenuation range of 10 dB is experimentally achieved by shifting the transmission spectrum at about 4.6 nm. The length of the ProPosed device is only 20 μm.
Surface-plasmon （SP） enhancement of amorphous-silicon-nitride （a-SiNx） light emission with single-layer gold （Au） waveguides is experimentally demonstrated through time-resolved photoluminescence measure- ment. The a-SiN~ active layer with strong steady-state photoluminescence at 560 nm is prepared by plasma-enhanced chemical vapor deposition, and ricated by magnetron sputtering. The maximum the Au waveguide on the top of the a-SiNx layer is lab- Purcell factor value of -3 is achieved with identified SP resonance of the Au waveguide at -530 nm.
