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Spatial modulation of second-harmonic generation via nonlinear Raman-Nath diffraction in an aperiodically poled
Yuping Chen1, Weirui Dang, Yuanlin Zheng
1State Key Laboratory on Fiber Optic Local Area Communication Networks and Advanced Optical Communication Systems, Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240, China. ypchen@sjtu.edu.cn
Optics Letters
|July 2, 2013
Summary
We demonstrate colorful nonlinear Raman-Nath second-harmonic generation using engineered nonlinear crystals. This method produces multicolored outputs in a uniform direction, independent of beam position.
Area of Science:
- Nonlinear optics
- Materials science
Background:
- Second-harmonic generation (SHG) is crucial for frequency conversion.
- Controlling nonlinear optical effects like Raman-Nath diffraction is challenging.
- Existing methods often lack directional control or color tunability.
Purpose of the Study:
- To achieve colorful nonlinear Raman-Nath second-harmonic generation.
- To demonstrate directional multicolored SHG outputs.
- To investigate the role of engineered quadratic nonlinearity in controlling diffraction.
Main Methods:
- Engineering the quadratic nonlinearity (χ((2))) in an aperiodically poled lithium tantalite crystal.
- Experimentally demonstrating nonlinear Raman-Nath second-harmonic generation.
- Analyzing the diffraction angles and output characteristics.
Main Results:
- Successfully generated colorful nonlinear Raman-Nath second-harmonic signals.
- Achieved multicolored SHG outputs along a uniform direction.
- Diffraction angles were found to be independent of beam waist and incidence position.
Conclusions:
- Engineered quadratic nonlinearity enables novel nonlinear optical phenomena.
- Nonlinear Raman-Nath diffraction depends on the entire nonlinear crystal, not local structures.
- This technique offers a new pathway for directional, multicolored frequency conversion.
