Design of AlGaN microring resonators for broadband biphoton excitation

Nowadays, Quantum Photonics finds a number of significant applications, such as Quantum Computing and Quantum Communication. Silicon on Insulator (SOI) technology has proven its potential for the generation of correlated photon pairs through the spontaneous four wave mixing (SFWM) effect, but not in the visible wavelength range. In this invited paper we present the physical investigation and design guidelines of AlGaN microring resonators for generating photon entanglement, as induced by SFWM in the visible. The work theoretically demonstrates the possibility of realizing the on-chip generation of correlated pairs of photons within integrated microring resonators based on the AlGaN/AlN technological platform, due to its wide bandgap, crystalline structure and low losses. Furthermore, general physical features are presented by means of a parametric analysis of the biphoton flux and cross correlation as a function of the device parameters, i.e. ring radius, resonator cross section and sizes, pulley coupling. Moreover, the spectral features of the generated signal and idler photons have been analyzed as a function of the pump resonance mismatch for several Kerr coefficients and input visible “blue” pump powers. Cross correlation values around 2.3 ×10
⁴
at a biphoton flux of about 9×10
⁴
pairs/s and 2×10
³
at about 2.9×10
⁶
pairs/s for ring radius of 200 μm and 30 μm have been achieved, respectively, assuming a input pump power of 25 mW, while the signal is generated at wavelength of 369.5 nm and idler at 535.72 nm, for ring radius of 200 μm, and 369.5 and 457.45 nm for ring radius of 30 μm, respectively. These devices can be important for many applications, going from UV-visible spectroscopy to quantum sensing to image processing to nonlinear optics.