Amorphous-silicon visible-light detector integrated on silicon nitride waveguides

Area of Science:

• Photonics and Optical Engineering
• Materials Science for Optoelectronics

Background:

• Visible-light integrated photonics is crucial for applications in sensing, quantum information, communications, imaging, and displays.
• High-index-contrast silicon nitride (Si3N4) waveguides are ideal for visible light due to broadband transparency and high integration.
• On-chip optical power monitoring is essential for complex photonic integrated circuits (PICs) to ensure stability and reconfiguration.

Purpose of the Study:

• To present a novel semi-transparent in-line power monitor for Si3N4 waveguides operating in the visible spectrum.
• To demonstrate the device's capability for high-sensitivity monitoring and control of visible-light PICs.

Main Methods:

• Integration of a hydrogenated amorphous-silicon (a-Si:H) photoconductive film evanescently coupled to Si3N4 waveguides.
• Operation at a red-light wavelength of 660 nm.
• Characterization of responsivity, sensitivity, and time response.

Main Results:

• The proposed device achieved a responsivity of 30 mA/W.
• A high sensitivity of -45 dBm was demonstrated.
• A fast sub-microsecond time response was recorded.

Conclusions:

• The developed a-Si:H photoconductor is suitable for in-line power monitoring in visible-light Si3N4 PICs.
• The device's performance enables precise control and stabilization of complex photonic systems.
• This technology advances the practical implementation of visible-light integrated photonic devices.