Nonlinear frequency conversion and manipulation of vector beams in a Sagnac loop.

Area of Science:

• Nonlinear Optics
• Quantum Optics
• Photonics

Background:

• Vector beams (VBs) possess unique intensity and polarization properties valuable for optical micromanipulation, microfabrication, communication, and imaging.
• Nonlinear frequency conversion (NFC) and manipulation of VBs are challenging due to the polarization sensitivity of conventional nonlinear optical processes.

Purpose of the Study:

• To experimentally demonstrate a novel method for nonlinear frequency conversion and manipulation of vector beams.
• To overcome the polarization dependence limitations in nonlinear processes involving VBs.
• To expand the accessible frequency bands for vector beam applications.

Main Methods:

• Introduction of a Sagnac loop to mitigate polarization dependence in nonlinear crystals during NFC.
• Transformation of linearly polarized VBs into hybrid-polarized VBs in exponential form prior to NFC.
• Experimental validation of the proposed scheme and comparison with theoretical models.

Main Results:

• Successful experimental realization of NFC and manipulation of VBs.
• Demonstrated effectiveness of the Sagnac loop in addressing polarization sensitivity.
• Experimental results show strong agreement with the developed theoretical model.

Conclusions:

• The proposed Sagnac loop-based method effectively enables NFC and manipulation of VBs, expanding their frequency range.
• The technique is versatile, applicable to various wavebands and second-order nonlinear processes.
• Potential for generalization to quantum regimes, including single-photon manipulation.