Optical probe for nondestructive wafer-scale characterization of photonic elements

Area of Science:

• Photonics
• Nanotechnology
• Microfabrication

Background:

• Nanophotonic devices and circuits require precise testing methods.
• Evanescent coupling is crucial for optical signal interaction in nanophotonics.

Purpose of the Study:

• To describe the fabrication and operation of a novel microfabricated photonic waveguide loop probe.
• To enable nondestructive, localized testing of nanophotonic devices and circuits.

Main Methods:

• Fabrication of a silicon (Si) waveguide loop probe (≈ 10 microm diameter) on a silicon on insulator (SOI) chip.
• Integration with a scanning probe microscope (SPM) for positioning and optical coupling control.
• Performing spectroscopy on a silicon microdisk optical cavity.

Main Results:

• Demonstrated successful fabrication and operation of the waveguide loop probe.
• Achieved controlled evanescent coupling for localized testing.
• Spectroscopy of a Si microdisk cavity yielded an optical quality factor of ≈ 10⁶.
• SPM enabled precise control of coupling regimes (under- to over-coupled).

Conclusions:

• The microfabricated photonic waveguide loop probe is effective for nondestructive testing of nanophotonic devices.
• The system allows for chip-scale and wafer-scale testing with high precision.
• This technology advances localized optical characterization of integrated photonic circuits.