Femtosecond laser-written mid-infrared waveguides in a heavy oxide germanate glass

Alexis Tryoen , Olivier Gazzano , Hussain Wajahat

Optics Letters +

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December 24, 2025

View abstract on PubMed

Summary

Researchers fabricated mid-infrared waveguides in germanate glass using a femtosecond laser multi-scan technique. This method achieved high refractive index contrast and low propagation loss for photonics integration.

Area Of Science

Materials Science
Optics and Photonics
Laser Physics

Background

Germanate glasses are promising materials for mid-infrared (MIR) applications.
Efficient fabrication of low-loss waveguides is crucial for MIR photonic devices.
Femtosecond laser writing offers precise control over material modification.

Purpose Of The Study

To fabricate and characterize mid-infrared waveguides in Corning 9754 germanate glass.
To investigate the potential of a femtosecond laser multi-scan technique for waveguide fabrication.
To assess the optical properties and modal characteristics of the fabricated waveguides.

Main Methods

Utilized a femtosecond laser multi-scan technique for waveguide inscription in germanate glass.
Characterized the waveguides by measuring refractive index profiles and propagation losses.
Employed Finite Difference Time Domain (FDTD) simulations to validate modal characteristics.

Main Results

Achieved smooth, positive transverse refractive index changes with a peak contrast of (1.2±0.07)⋅10<sup>-2</sup> at 600 nm.
Demonstrated low propagation loss of 0.5±0.1 dB/cm at a wavelength of 3.2 µm.
Obtained circular mid-infrared guided modes through fine-tuning of writing parameters.

Conclusions

The femtosecond laser multi-scan technique provides effective control over waveguide properties in germanate glass.
The fabricated waveguides exhibit excellent performance for mid-infrared photonics.
This approach is validated for future mid-infrared photonic integrated circuit development.