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Intracavity parametric generation of nanosecond terahertz radiation using quasi-phase-matching
David A Walsh1, Peter G Browne, Malcolm H Dunn
1J. F. Allen Research Laboratories, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, UK. dw32@st-andrews.ac.uk
Optics Express
|July 1, 2010
Summary
Researchers generated terahertz radiation using quasi-phase-matching in periodically-poled lithium niobate. The study explored cascaded difference frequency generation and optimized grating parameters for efficient terahertz output.
Area of Science:
- Photonics and Optics
- Nonlinear Optics
- Terahertz (THz) Science
Background:
- Optical parametric oscillators (OPOs) are crucial for generating tunable coherent light.
- Terahertz (THz) radiation generation is challenging due to material limitations and phase-matching requirements.
- Periodically-poled ferroelectric materials offer versatile nonlinear optical properties for frequency conversion.
Purpose of the Study:
- To investigate the generation of nanosecond THz pulses using quasi-phase-matching in MgO:LiNbO3.
- To analyze the underlying nonlinear processes, including parametric down-conversion and cascaded difference frequency generation.
- To explore the impact of grating geometries on THz generation efficiency and oscillation thresholds.
Main Methods:
- Utilized intracavity optical parametric oscillators.
- Employed quasi-phase-matching techniques with periodically-poled magnesium oxide-doped lithium niobate (MgO:LiNbO3).
- Conducted temporal studies to analyze the generated idler-waves and nonlinear processes.
- Investigated various grating geometries for optimizing THz generation.
Main Results:
- Successfully generated nanosecond duration pulses of THz radiation.
- Observed both parametric down-conversion and subsequent cascaded difference frequency generation.
- Identified dual solutions for the quasi-phase-matching process in periodically-poled MgO:LiNbO3.
- Demonstrated the influence of grating parameters on oscillation threshold and THz extraction efficiency.
Conclusions:
- Quasi-phase-matching in MgO:LiNbO3 is an effective method for nanosecond THz pulse generation.
- Understanding cascaded nonlinear processes is key to optimizing THz output.
- Careful selection of grating parameters is essential for efficient THz generation in OPOs.
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