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Low loss Si(3)N(4)-SiO(2) optical waveguides on Si
Applied Optics
|May 22, 2010
Summary
We developed silicon nitride (Si3N4) optical waveguides using silicon processing, achieving low losses (<0.3 dB/cm). Annealing effectively reduced hydrogen-related absorption peaks in the infrared spectrum.
Area of Science:
- Integrated Optics
- Materials Science
- Semiconductor Processing
Background:
- Optical integrated circuits require low-loss waveguides compatible with silicon fabrication.
- Silicon nitride (Si3N4) on silicon dioxide (SiO2) offers a high refractive index contrast for mode confinement.
Purpose of the Study:
- To develop and characterize Si3N4 optical waveguide technology using standard silicon processing.
- To assess waveguide performance, including loss and infrared absorption.
- To investigate methods for mitigating absorption losses.
Main Methods:
- Fabrication of Si3N4/SiO2 waveguides using conventional Si processing.
- Measurement of waveguide propagation losses in the 1.3-1.6 micrometer range.
- Infrared transmission spectroscopy to identify and quantify absorption peaks.
- Annealing experiments to reduce absorption.
Main Results:
- Achieved waveguide losses below 0.3 dB/cm in the 1.3-1.6 micrometer range.
- Identified two hydrogen-related absorption peaks at 1.40 microm (Si3N4) and 1.52 microm (SiO2).
- Peak absorptions were 2.2 dB/cm and 1.2 dB/cm, respectively.
- Annealing at 1100-1200 degrees C significantly reduced these absorption peaks.
Conclusions:
- Demonstrated a viable Si3N4 waveguide technology for optical integrated circuits using Si processing.
- Identified and quantified hydrogen-induced absorption, a key limitation for certain applications.
- Showcased annealing as an effective post-processing step to enhance waveguide performance for infrared applications.
