Low-loss, low-background aluminum oxide waveguide platform for broad-spectrum on-chip microscopy.

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Photonic integrated circuits (PICs) are crucial for on-chip optical microscopy and spectroscopy.
• Key requirements for PICs include low loss, low autofluorescence, and high refractive index contrast for compact designs.
• Existing platforms often struggle to meet all these requirements across a wide spectral range.

Purpose of the Study:

• To develop a versatile, wide-spectrum photonic integrated circuit (PIC) platform.
• To address the need for low-loss, low-autofluorescence, and high-refractive index contrast waveguides.
• To demonstrate the suitability of the platform for advanced bioimaging applications.

Main Methods:

• Utilized atomic layer deposition (ALD) to fabricate aluminum oxide (Al2O3) waveguides.
• Characterized Al2O3 strip waveguides at 405 nm for propagation loss and autofluorescence.
• Integrated the Al2O3 platform into multicolor on-chip total internal reflection fluorescence (TIRF) and super-resolution microscopy setups.

Main Results:

• Achieved a low propagation loss of less than 0.5 dB/cm for Al2O3 waveguides.
• Demonstrated an autofluorescence background approximately 200 times lower than silicon nitride (Si3N4) at 405 nm.
• Successfully applied the Al2O3 platform to multicolor on-chip TIRF and super-resolution optical microscopy.

Conclusions:

• The developed Al2O3 waveguide platform offers a promising solution for sensitive on-chip bioimaging.
• The platform's low loss and low autofluorescence are advantageous for UV to IR applications.
• This advancement enables highly sensitive on-chip spectroscopy and microscopy.