We demonstrate the coherent frequency conversion of structured light, optical
beams in which the phase varies in each point of the transverse plane, from the
near infrared (803nm) to the visible (527nm). The frequency conversion process
makes use of sum-frequency generation in a periodically poled lithium niobate
(ppLN) crystal with the help of a 1540-nm Gaussian pump beam. We perform
far-field intensity measurements of the frequency-converted field, and verify
the sought-after transformation of the characteristic intensity and phase
profiles for various input modes. The coherence of the frequency-conversion
process is confirmed using a mode-projection technique with a phase mask and a
single-mode fiber. The presented results could be of great relevance to novel
applications in high-resolution microscopy and quantum information processing

Hermosa, Nathaniel

Pruneri, Valerio

Steinlechner, Fabian

Torres, Juan P.

Scientific Reports

English

arXiv

Coherent frequency conversion of structured light, i.e. the ability to manipulate the carrier frequency of a wave front without distorting its spatial phase and intensity profile, provides the opportunity for numerous novel applications in photonic technology and fundamental science. In particular, frequency conversion of spatial modes carrying orbital angular momentum can be exploited in sub-wavelength resolution nano-optics and coherent imaging at a wavelength different from that used to illuminate an object. Moreover, coherent frequency conversion will be crucial for interfacing information stored in the high-dimensional spatial structure of single and entangled photons with various constituents of quantum networks. In this work, we demonstrate frequency conversion of structured light from the near infrared (803¿nm) to the visible (527¿nm). The conversion scheme is based on sum-frequency generation in a periodically poled lithium niobate crystal pumped with a 1540-nm Gaussian beam. We observe frequency-converted fields that exhibit a high degree of similarity with the input field and verify the coherence of the frequency-conversion process via mode projection measurements with a phase mask and a single-mode fiber. Our results demonstrate the suitability of exploiting the technique for applications in quantum information processing and coherent imaging.Peer ReviewedPostprint (published version

Pérez Torres, Juan

UPCommons. Portal del coneixement obert de la UPC

Frequency conversion of structured light

Frequency conversion of structured light

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