Self-traceable nano-grating frequency doubling based on polarization gradient light field

Abstract

Self-traceable gratings with small scale are much desired in nano-metrology. Atom lithography is the fundamental technique to fabricate self-traceable gratings but the resolution of grating pitch is usually limited by the laser wavelength. To lower down the grating scale, an approach introducing the polarization gradient light field was demonstrated here to achieve the gratings frequency doubling. The influences of polarization gradient standing wave field and cooling light field on the internal atomic structure were first analyzed to illustrate the principle of frequency doubling. And it has been proven that the grating pitch can still perfectly keep traceable to the laser wavelength. Then a quarter-wavelength (λ/4) pitch of 106.4nm self-traceable grating was fabricated experimentally by atom lithography using 425.55nm laser. This approach is hopeful to realize the λ/8 pitch as well, which provides an effective way to fabricate the smaller-scale self-traceable gratings.