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Enhanced harmonic generation by breaking the phase-matching symmetry
G N Gibson1, N Majtenyi, E Sergan
1Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA. gibson@phys.uconn.edu
Optics Letters
|August 4, 2012
Summary
We present two methods to improve third harmonic generation (THG) efficiency by disrupting phase-matching symmetry. These techniques prevent harmonic cancellation after the beam focus, enhancing conversion efficiency and mode quality.
Area of Science:
- Nonlinear optics
- Laser physics
- Quantum optics
Background:
- Third harmonic generation (THG) is a key nonlinear optical process.
- Phase-matching symmetry in THG with focused beams leads to cancellation and reduced efficiency.
- Improving THG conversion efficiency and beam quality is crucial for applications.
Purpose of the Study:
- To introduce novel methods for breaking phase-matching symmetry in THG.
- To significantly enhance THG conversion efficiency and mode quality.
- To overcome the limitations of harmonic cancellation in focused beams.
Main Methods:
- Developing two static methods to inhibit THG after the beam waist.
- Method 1: Utilizing a thin metal septum at the beam waist to create a pinhole, disrupting the focus.
- Method 2: Employing spatially distinct nonlinear media with different nonlinear susceptibilities (χ(3)) before and after the focus.
Main Results:
- Both methods successfully break phase-matching symmetry, preventing harmonic cancellation.
- Dramatic increases in THG conversion efficiency were observed.
- Significant improvements in the mode quality of the generated third harmonic beam were achieved.
Conclusions:
- The proposed static methods offer a robust way to enhance THG performance.
- Breaking phase-matching symmetry is a viable strategy for efficient nonlinear frequency conversion.
- These advancements pave the way for more effective THG-based technologies.
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