Abstract
Active silicon photonic devices, which dynamically control the flow of light, have received significant attention for their use in on-chip optical networks. High-speed active silicon photonic modulators and switches rely on the plasma dispersion effect, where a change in carrier concentration causes a variation in the refractive index. The necessary electron and hole concentration change can be introduced either by optical pumping, or by direct electrical injection and depletion. We demonstrate a fast photoinduced absorption effect in low loss hydrogenated amorphous silicon (a-Si:H) waveguides deposited at a temperature as low as 190°C. Significant modulation (M% ~90%) occurs with a 1 mm-long device. We attribute the enhanced modulation to the significantly larger free-carrier absorption effect of a-Si:H. The complementary metal-oxide semiconductor (CMOS) compatible technology of a-Si:H could be considered as a promising candidate to enable an easy back-end integration with standard microelectronics processes.
Highlights
D’AddioActive silicon photonic devices, which dynamically control the flow of light, have received significant attention for their use in on-chip optical networks
Photonics is a rapidly growing sector in the global economy
The device, realised on a p-doped crystalline silicon (c-Si) substrate (ρ=0.001 Ω·cm), consists of a rib waveguide made of a 3-μm-thick amorphous silicon (a-Si):H undoped layer on a 400 nm-thick SiO2 low refractive index cladding ensuring a vertical optical confinement
Summary
Active silicon photonic devices, which dynamically control the flow of light, have received significant attention for their use in on-chip optical networks. High-speed active silicon photonic modulators and switches rely on the plasma dispersion effect, where a change in carrier concentration causes a variation in the refractive index. The necessary electron and hole concentration change can be introduced either by optical pumping, or by direct electrical injection and depletion. Significant modulation (M% ∼90%) occurs with a 1 mm-long device. We attribute the enhanced modulation to the significantly larger free-carrier absorption effect of a-Si:H.
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