Sub-1 dB/cm submicrometer-scale amorphous silicon waveguide for backend on-chip optical interconnect.

Area of Science:

• Photonics and Materials Science
• Integrated Optics

Background:

• Hydrogenated amorphous silicon (a-Si:H) is a promising material for optical waveguides.
• Achieving low propagation loss in submicrometer waveguides is critical for advanced photonic integrated circuits.

Purpose of the Study:

• To demonstrate a submicrometer-scale a-Si:H waveguide with significantly reduced propagation loss.
• To optimize waveguide structure and fabrication for low optical absorption and CMOS compatibility.

Main Methods:

• Fabrication of a submicrometer waveguide with a 440 nm thick and 780 nm wide core and a 100 nm thick ridge structure.
• Utilized low-cost i-line stepper photolithography and low-temperature processing (<350°C).
• Characterized optical propagation loss using precise measurements.

Main Results:

• Achieved a record low propagation loss of 0.60 ± 0.02 dB/cm.
• Demonstrated the effectiveness of low-defect a-Si:H film in reducing infrared optical absorption.
• Confirmed compatibility with complementary metal oxide semiconductor (CMOS) backend fabrication processes.

Conclusions:

• The developed a-Si:H waveguide offers superior performance for integrated photonics.
• Low-temperature, low-cost fabrication methods enable mass production and integration with existing semiconductor manufacturing.
• This work paves the way for next-generation silicon photonics devices.