High-harmonic generation by resonant plasmon field enhancement

Area of Science:

• Optics and Photonics
• Materials Science
• Quantum Electronics

Background:

• High-harmonic generation (HHG) is a key method for producing coherent extreme-ultraviolet (EUV) light.
• Conventional HHG requires high laser intensities (>10^13 W cm^-2), typically achieved through complex chirped-pulse amplification systems with multiple cavities.
• These systems are bulky and limit the practicality of EUV light sources.

Purpose of the Study:

• To demonstrate a novel, compact method for high-harmonic generation that avoids the need for additional amplifier cavities.
• To leverage localized field enhancement in metallic nanostructures for efficient nonlinear optical processes.
• To enable the development of portable EUV light sources for applications like lithography and imaging.

Main Methods:

• Utilized resonant plasmon enhancement in a metallic nanostructure (bow-tie gold elements on sapphire).
• Focused output from a modest femtosecond laser oscillator directly onto the nanostructure.
• Employed an argon gas jet for EUV light generation via high-harmonic generation.

Main Results:

• Achieved significant local field enhancement (>20 dB) at the nanostructure surface.
• Generated EUV light down to 47 nm using a low-intensity laser (10^11 W cm^-2).
• Demonstrated efficient HHG without requiring chirped-pulse amplification or extra cavities.

Conclusions:

• Plasmon-enhanced HHG in metallic nanostructures offers a pathway to compact and efficient EUV light generation.
• This method significantly reduces the complexity and size requirements for EUV sources.
• The technology holds promise for creating laptop-sized EUV light sources for advanced applications.