We worked on a new scheme of quasi-phase matching (QPM) based on the negative first order of the spatial modulation of the sign of the second-order nonlinearity. Applying this scheme in the case of angular-QPM (AQPM) in a biaxial crystal reveals new directions of propagation for efficient parametric frequency conversion as well as "giant" spectral acceptances. The experimental validation is performed in a periodically poled rubidium-doped biaxial crystal. This new approach naturally extends to other periodically poled uniaxial crystals such as periodically poled .
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http://dx.doi.org/10.1364/OL.408839 | DOI Listing |
npj Quantum Inf
December 2024
ETH Zurich, Department of Physics, Institute for Quantum Electronics, Optical Nanomaterial Group, Auguste-Piccard-Hof, 1, 8093 Zurich, Switzerland.
Optical quantum communication technologies are making the prospect of unconditionally secure and efficient information transfer a reality. The possibility of generating and reliably detecting quantum states of light, with the further need of increasing the private data-rate is where most research efforts are focusing. The physical concept of entanglement is a solution guaranteeing the highest degree of security in device-independent schemes, yet its implementation and preservation over long communication links is hard to achieve.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510641, China.
Linear optical diffraction of light is a basic natural phenomenon subject to a long history study and it obeys the well-known reciprocity in transport. In this work we report observation of synergistic nonreciprocal linear and nonlinear diffraction of a Ti:sapphire femtosecond laser beam against a periodic poled lithium niobate (PPLN) thin plate nonlinear grating with a front surface corrugated with a shallow grating of a depth only 67 nm and a smooth back surface. A high peak power pump laser beam shining upon the geometrically asymmetric nonlinear grating from either the front surface and back surface will both cause significant second-order nonlinear (2nd-NL) Raman-Nath diffraction and Cerenkov radiation, in addition to apparent linear optical diffraction and modest third-order nonlinear (3rd-NL) spectral broadening.
View Article and Find Full Text PDFThe indistinguishable photon-pair sources are valuable in many quantum information applications, such as quantum microscopy, quantum synchronization, and quantum metrology. Based on cascaded sum-frequency generation (SFG) and spontaneous parametric downconversion (SPDC) processes, we propose and demonstrate a scheme for the generation of spatially separated broadband indistinguishable photon pairs in the telecom band by using only one piece of a fiber-pigtailed periodically poled lithium niobate waveguide in a modified Sagnac loop. The measured joint spectral intensity of the generated entangled photon pairs is 7.
View Article and Find Full Text PDFNanophotonics
August 2024
Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Photonics offers unique capabilities for quantum information processing (QIP) such as room-temperature operation, the scalability of nanophotonics, and access to ultrabroad bandwidths and consequently ultrafast operation. Ultrashort pulse sources of quantum states in nanophotonics are an important building block for achieving scalable ultrafast QIP; however, their demonstrations so far have been sparse. Here, we demonstrate a femtosecond biphoton source in dispersion-engineered periodically poled lithium niobate nanophotonics.
View Article and Find Full Text PDFNanophotonics
August 2024
National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
Photonic devices based on ferroelectric domain engineering in thin film lithium niobate are key components for both classical and quantum information processing. Periodic poling of ridge waveguide can avoid the selective etching effect of lithium niobate, however, the fabrication of high-quality ferroelectric domain is still a challenge. In this work, we optimized the applied electric field distribution, and rectangular inverted domain structure was obtained in the ridge waveguide which is beneficial for efficient nonlinear frequency conversions.
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