Sub-wavelength light localization in nanorod chain enhances second-harmonic generation

Area of Science:

• Photonics and Nanotechnology
• Nonlinear Optics
• Materials Science

Background:

• Second-harmonic generation (SHG) is crucial for frequency conversion in optics.
• Enhancing SHG efficiency in compact devices remains a significant challenge.
• Subwavelength light confinement offers potential for boosting nonlinear optical processes.

Purpose of the Study:

• To investigate the use of nonlinear dielectric nanorod chains for enhanced second-harmonic generation.
• To explore the underlying physical mechanisms responsible for efficiency enhancement.
• To demonstrate the feasibility of highly integrated and efficient nonlinear optical devices.

Main Methods:

• Fabrication of nonlinear dielectric nanorod chains.
• Experimental measurement of second-harmonic generation efficiency.
• Numerical simulations to analyze light confinement and mode squeezing.
• Investigation of slow light effects at fundamental and second-harmonic frequencies.

Main Results:

• Achieved a second-harmonic generation conversion efficiency exceeding 10% with a 20-nanorod chain.
• Demonstrated efficiency with low input pump peak power (200 W).
• Observed efficient frequency conversion attributed to lateral squeezing of the fundamental mode.
• Identified the role of slow light at both fundamental (omega) and second-harmonic (2 omega) frequencies.

Conclusions:

• Nonlinear dielectric nanorod chains effectively enhance second-harmonic generation.
• Subwavelength confinement and slow light are key mechanisms for efficient frequency conversion.
• These findings pave the way for designing compact and efficient nonlinear optical devices.