On-chip quadratically nonlinear photodetector

Area of Science:

• Photonics
• Materials Science
• Integrated Optics

Background:

• Deterministic nonlinear photoresponse is crucial for advanced functions in photonic integrated circuits.
• On-chip devices for such functions, like in-sensor computing and optoelectronic mixing, require further investigation.

Purpose of the Study:

• To demonstrate an on-chip quadratically nonlinear photodetector (QNPD) with enhanced functionalities.
• To leverage InSe's properties for efficient second-harmonic generation (SHG) and photocurrent generation.

Main Methods:

• Fabrication of an InSe p-i-n homojunction on a silicon waveguide.
• Utilizing evanescent coupling for frequency up-conversion via SHG in InSe.
• Generating photocurrent through absorption and the built-in electric field.

Main Results:

• The QNPD exhibited a quadratic relationship between photocurrent and optical power.
• Achieved a high normalized responsivity of 37.1 A/W².
• Demonstrated an on-chip autocorrelator for picosecond pulse measurement with high sensitivity (6.1×10^-10 W²).

Conclusions:

• The developed QNPD integrates light-light interactions for electrical monitoring of all-optically mixed signals.
• The device shows significant performance improvements over existing nonlinear photodetectors.
• The QNPD technology enables sophisticated on-chip optical signal processing and measurement applications.