Direct UV written integrated planar waveguides using a 213 nm laser

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Integrated optical devices are crucial for modern communication and sensing.
• Direct UV writing is a technique for fabricating optical waveguides.
• Previous methods often require higher laser fluences and longer fabrication times.

Purpose of the Study:

• To demonstrate the first integrated waveguides in planar silica devices using direct UV writing with a 213 nm laser.
• To characterize the fabricated waveguides in terms of numerical aperture (NA) and mode field diameter (MFD).
• To assess the fabrication speed and propagation loss.

Main Methods:

• Fabrication of silica waveguides using direct UV writing with a 213 nm laser at various fluences.
• Measurement of Numerical Aperture (NA) and Mode Field Diameter (MFD) for each waveguide.
• Cutback measurements to determine propagation loss.

Main Results:

• Single-mode waveguides were achieved at significantly lower fluences compared to 244 nm laser systems, enabling rapid fabrication.
• A maximum in-plane refractive index change of 2.4 × 10^-3 was estimated.
• Directly measured propagation loss was 0.42 ± 0.07 dB cm^-1, with calculated losses as low as 0.2 ± 0.03 dB/cm.

Conclusions:

• Direct UV writing with a 213 nm laser is an effective method for fabricating integrated waveguides in planar silica.
• The technique offers advantages in fabrication speed and achievable index change.
• The demonstrated low propagation losses indicate suitability for optical device applications.