High-sensitivity transparent photoconductors in voltage-controlled silicon waveguides

Area of Science:

• Photonics
• Integrated Optics
• Semiconductor Devices

Background:

• On-chip optical power monitors are critical for calibrating, stabilizing, and reconfiguring photonic integrated circuits (PICs).
• In-line waveguide detectors face a trade-off between high sensitivity and transparency to guided light.

Purpose of the Study:

• To demonstrate a novel transparent photoconductor for in-line optical power monitoring on silicon-on-insulator (SOI) waveguides.
• To achieve high photoconductive gain and in-line sensitivity simultaneously.

Main Methods:

• Integration of a transparent photoconductor onto standard low-doped SOI waveguides.
• Application of bias voltage to the chip substrate or a local gate electrode to compensate for electric charges.
• Tuning the waveguide core conductivity to an optimal level on demand.

Main Results:

• Demonstration of a transparent photoconductor with a photoconductive gain exceeding 10^6.
• Achieved high in-line sensitivity of -60 dBm.
• Successful compensation of cladding oxide charge effects via applied bias voltage.

Conclusions:

• The developed transparent photoconductor offers a significant advancement for in-line optical power monitoring in PICs.
• The method allows for on-demand tuning of waveguide conductivity, overcoming traditional sensitivity-transparency trade-offs.
• This technology is essential for precise control and operation of complex photonic systems.