Digital Holography Using Harmonic Generation from Solids for Reconstruction of Subwavelength Nanostructures

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Digital holographic microscopy (DHM) is a key technique for phase assessment in imaging.
• Nonlinear optical processes, like high-harmonic generation, offer enhanced sensitivity for nanoscale characterization.

Purpose of the Study:

• To demonstrate the combined use of DHM and harmonic generation for 3D sample reconstruction.
• To investigate the characterization of subwavelength periodic structures with improved accuracy.

Main Methods:

• Combining digital holographic microscopy (DHM) with nonlinear harmonic generation from solid materials.
• Utilizing near-infrared (NIR) probing laser sources.
• Analyzing high-harmonic generation for structural parameter investigation.

Main Results:

• Reliable 3D reconstructions of samples were achieved.
• Discrimination of silicon gratings with critical dimension changes of tens of nanometers.
• Resolution of structures with pitches as small as 400 nm, below the NIR laser wavelength.

Conclusions:

• The DHM and harmonic generation combination reliably reconstructs 3D samples and characterizes subwavelength structures.
• The technique offers improved accuracy for nanostructure analysis, particularly for periodic gratings.
• This method holds potential for sensing subwavelength structures in industries like semiconductors.