SPAD-based time-of-flight for dispersion measurement of integrated waveguides

Area of Science:

• Photonics and optical engineering
• Materials science for integrated optics
• Waveguide dispersion characterization

Background:

• Precise control of light propagation via dispersion engineering is vital for compact photonic systems like chip-integrated sources and amplifiers.
• Current dispersion characterization methods for photonic devices are often complex and lack accessibility, hindering device design.
• Manipulating light pulses and exploiting nonlinear phenomena in waveguides requires accurate dispersion management.

Purpose of the Study:

• To present a versatile and broadly accessible dispersion characterization technique for integrated photonic waveguides.
• To demonstrate a method that is insensitive to chip-coupling efficiency and alignment variations.
• To accurately measure the dispersion parameter in ultra-low-loss silicon nitride waveguides.

Main Methods:

• Utilized single photon avalanche diode (SPAD)-based time-of-flight (ToF) measurements.
• Applied the SPAD-ToF technique to characterize dispersion in integrated waveguides.
• Focused on ultra-low-loss silicon nitride (SiN) spiral waveguides for testing.

Main Results:

• Successfully demonstrated SPAD-ToF dispersion measurements for integrated waveguides.
• The method proved insensitive to variations in chip-coupling efficiency and alignment.
• Accurately measured both the magnitude and sign of the dispersion parameter in SiN waveguides.

Conclusions:

• SPAD-based ToF is a robust and accessible technique for characterizing waveguide dispersion.
• This method facilitates the development of advanced photonic devices requiring precise dispersion control.
• Enables accurate dispersion measurements in ultra-low-loss SiN waveguides, supporting integrated optics advancements.