Extended depth-of-focus femtosecond laser pulses for flexible micromachining

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Traditional optical systems have limited depth-of-focus, restricting applications requiring precise laser manipulation over extended ranges.
• Femtosecond (fs) laser pulses offer high precision but are constrained by shallow focal depths.

Purpose of the Study:

• To introduce a novel method for extending the depth-of-focus (EDOF) of intense fs pulses.
• To demonstrate the practical utility of this EDOF method in laser-based material processing.

Main Methods:

• Design and fabrication of a flat, thin multilevel diffractive lens (MDL).
• Characterization of fs-pulse focusing and propagation through the MDL.
• Evaluation of laser filamentation and material processing with extended depth-of-focus.

Main Results:

• The MDL successfully extended the depth-of-focus for fs pulses significantly beyond conventional lenses.
• Consistent spatial resolution was achieved during laser marking and machining in glass over the extended depth-of-focus.
• Demonstrated laser filamentation with long plasma channels.

Conclusions:

• The developed MDL offers a simple and efficient solution for extending the depth-of-focus of fs pulses.
• This technology facilitates high-throughput, compact in-line fs-micromachining.
• Potential applications include micro-optics fabrication, microfluidics, and nanosurgery.