Inscription of silicon waveguides using picosecond pulses.

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Physics

Background:

• Waveguide fabrication is crucial for integrated photonics.
• Direct laser writing offers precise control over material modification.
• Crystalline silicon is a key material for optoelectronic devices.

Purpose of the Study:

• To demonstrate direct writing of single-mode waveguides in crystalline silicon using picosecond (ps) laser pulses.
• To analyze the in-situ processing dynamics and waveguide characteristics.
• To showcase the potential for fabricating integrated optical components.

Main Methods:

• Fabrication of embedded waveguides by moving the focal position along the beam axis using a long-distance microscope objective.
• In-situ monitoring of the inscription process to understand dynamics.
• Characterization of waveguide mode field distribution and damping losses.
• Analysis of induced refractive index changes.

Main Results:

• Successful inscription of single-mode waveguides in crystalline silicon.
• Waveguide generation attributed to multi-pulse interaction at ~100 nJ pulse energy.
• Measured damping losses and mode field distributions.
• Calculated induced refractive index change between 10⁻³ and 10⁻².
• Demonstration of a Y-splitter fabricated using this technique.

Conclusions:

• Direct laser writing with ps pulses is a viable method for creating single-mode waveguides in crystalline silicon.
• The process allows for precise control and fabrication of embedded optical structures.
• This technique holds promise for developing advanced silicon photonic integrated circuits.