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Light absorption in hybrid silicon-on-insulator/quantum dot waveguides
Optics Express
|October 10, 2013
Summary
Quantum dots (QDs) enhance silicon-on-insulator waveguide absorption at 1500 nm. Thicker QD layers show stronger absorption due to changes in the effective dielectric constant, moving from extrinsic to intrinsic film properties.
Area of Science:
- Materials Science
- Nanotechnology
- Optoelectronics
Background:
- Silicon-on-insulator (SOI) waveguides are crucial for optical communication.
- Colloidal quantum dots (QDs) offer tunable optical properties.
- Integrating QDs with waveguides can enhance light-matter interaction.
Purpose of the Study:
- To analyze the absorption coefficient of SOI waveguides functionalized with PbS/CdS quantum dots.
- To understand the relationship between QD layer thickness and optical absorbance.
- To develop a model simulating the absorption in QD-coated waveguides.
Main Methods:
- Experimental measurement of waveguide absorbance with mono- and multilayers of QDs.
- Modeling the QD layer as an effective medium with a dielectric function.
- Utilizing dipolar coupling and a host dielectric constant (εh) as an adjustable parameter for simulation.
Main Results:
- Observed significant influence of QDs on waveguide absorbance around 1500 nm.
- Demonstrated stronger absorption in thicker QD layers.
- Achieved excellent agreement between experimental data and simulations by adjusting εh.
Conclusions:
- The increasing absorption cross-section with layer thickness is attributed to an increasing εh.
- This εh evolution indicates a transition from extrinsic (monolayer) to intrinsic (multilayer) film properties.
- The findings provide insights into designing QD-enhanced optical devices.
