The polarization of traditional photonic crystal（PC） vertical cavity surface emitting laser（VCSEL） is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently.We analyze the far field divergence angle,and birefringence of elliptical hole PC VCSEL.When the ratio of minor axis to major axis b/a = 0.7,the PC VCSEL can obtain single mode and polarization.According to the simulation results,we fabricate the device successfully.The output power is 1.7 mW,the far field divergence angle is less than 10°,and the side mode suppression ratio is over 30 dB.The output power in the Y direction is 20 times that in the X direction.
A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.
The effect of shape, height, and interparticle spacing of Au nanoparticles （NPs） on the sensing performance of Au NP array is systematically investigated. Lengthening the major axis of elliptical NPs with the minor axis kept constant will cause the redshift of the local surface plasmon （LSP） resonance mode, enhance the sensitivity, and widen the resonance peaks. Larger height corresponds to smaller LSP resonance wavelength and narrower resonance peak. With each NP size unchanged, larger interparticle spacing corresponds to larger resonance wavelength and smaller full-width at half-maximum （FWHM）. Moreover, duty cycle is important for sensitivity, which is largest when the duty cycle is 0.4.
A novel silicon-on-insulator microring biosensor based on Young＇s twoslit interference has been demonstrated. The transducer signal from electric field intensity distribution on the interference screen is given by using the transfer matrix method（TMM） and two-slit interference principle.The result shows that the structure we propose is advantageous for sensing as the interference pattern is very sensitive to the ambient refractive index around the microring.A small perturbation in refractive index around the microring△n_c will result in a notable shift of destructive interference points（DIPs） on the interference screen.By detecting the shift of the DIPs,the ambient refractive index change can be obtained.
