Ultra-low loss visible light waveguides for integrated atomic, molecular, and quantum photonics

Area of Science:

• Atomic, Molecular, and Optical (AMO) Physics
• Integrated Photonics
• Materials Science

Background:

• Atomic, molecular, and optical (AMO) systems are crucial for precision applications like atomic clocks and metrology.
• Scaling AMO systems demands integrated photonic solutions to overcome limitations of traditional lasers and optics.
• Existing visible light integrated photonics face challenges with waveguide losses and laser stability.

Purpose of the Study:

• To report the lowest waveguide losses and highest resonator Qs in the visible light spectrum.
• To demonstrate a wafer-scale, CMOS-compatible photonic platform for AMO applications.
• To enable advancements in integrated visible light systems for quantum technologies and precision measurements.

Main Methods:

• Fabrication of silicon nitride (Si3N4) waveguides with a 20 nm core and TEOS-PECVD upper cladding.
• Characterization of waveguide losses across the 461 nm to 802 nm wavelength range.
• Measurement of intrinsic and absorption-limited resonator quality (Q) factors.

Main Results:

• Achieved waveguide losses as low as 0.01 dB/cm and resonator Qs up to 60 million in the visible range.
• Demonstrated a 6x to 2x reduction in loss and a 10x to 1.5x increase in Q compared to previous visible light waveguides.
• Measured absorption-limited loss of 0.17 dB/m and Q of 340 million at 674 nm.
• Showcased the ability to fabricate waveguides for multiple wavelengths on a single wafer using mask-only changes.

Conclusions:

• The developed Si3N4 platform offers unprecedented performance for visible light integrated photonics.
• These advancements are critical for realizing miniaturized, high-performance AMO devices.
• The platform opens possibilities for integrated sensors, navigation systems, and advanced metrology and clocks.