Crossed femtosecond filaments create plasma grating in air

Nov. 9, 2011
A group at East China Normal University has shown self-channeling filaments created by femtosecond-laser pulses can interact in air to form a 2D plasma grating that diffracts light.

A group at East China Normal University (Shanghai, China) has shown self-channeling filaments created by femtosecond-laser pulses can interact in air to form a 2D plasma grating that diffracts light. The team split 50 fs pulses at a 1 kHz repetition rate from a Ti:sapphire laser into three equal-energy pulses, each of which is focused into an air region so the filaments (and the synchronized pulses) cross each other at angles from 3º to 6º. The resulting interference-induced gratings were enhanced by nonlinear Kerr and plasma effects and formed channels a few millimeters long. The input pulses were guided into the plasma channels; noncollinear pulses at arbitrary incidence angles could be coupled into the channels.

The plasma structures were characterized using time-resolved holographic imaging, with the weak test probe propagating perpendicularly through the plasma grating. From the measured phase profile, the change in refractive index for a single filament, a 1D grating, and a 2D grating were 1.47 × 10-5, 2.21 × 10-4, and 3.53 × 10-4, respectively. Third-harmonic pulses generated in air by the filaments were diffracted by the gratings as per the Bragg condition, confirming the measurements. Potential uses include plasma photonics for pulse compression and shaping. Contact Heping Zang at[email protected].

Sponsored Recommendations

How to Tune Servo Systems: Force Control

Oct. 23, 2024
Tuning the servo system to meet or exceed the performance specification can be a troubling task, join our webinar to learn to optimize performance.

Laser Machining: Dynamic Error Reduction via Galvo Compensation

Oct. 23, 2024
A common misconception is that high throughput implies higher speeds, but the real factor that impacts throughput is higher accelerations. Read more here!

Boost Productivity and Process Quality in High-Performance Laser Processing

Oct. 23, 2024
Read a discussion about developments in high-dynamic laser processing that improve process throughput and part quality.

Precision Automation Technologies that Minimize Laser Cut Hypotube Manufacturing Risk

Oct. 23, 2024
In this webinar, you will discover the precision automation technologies essential for manufacturing high-quality laser-cut hypotubes. Learn key processes, techniques, and best...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!