Dual-core optical fibers for efficient mid-infrared generation via third-order frequency mixing and coupling-length phase matching

Abstract

Appropriately designed dual-core fibers using coupling-length phase matching (CLPM) allow for phase-matched frequency downconversion over wide frequency intervals using the third-order optical nonlinearity of glass. By tuning the distance between the two cores, CLPM allows continuously tunable phase matching for widely different wavelengths for the process in which a pump wave at a frequency ω 2 generates or amplifies two waves with frequencies ω 3 > ω 2 and ω 1 = 2 ω 2 − ω 3 . The intensity-dependent correction that accounts for nonlinear phase modulation is derived in general. In addition, a specific CLPM configuration is found to be insensitive to phase modulation, and can achieve 100% theoretical quantum yield for pump wave injection in one core. Fiber-based frequency converters can thus be designed for large differences between pump wavelengths and generated wavelengths, with the phase-matched interaction enabling the use of meter-long fibers to compensate for low third-order susceptibilities. Examples of fiber designs for pump wavelengths at 1.3 and 1.55 µ m , to generate radiation with wavelengths longer than 2 µ m , are discussed for silica and fluoride fibers.

Parametric amplification in coupled nonlinear waveguides: The role of coupling dispersion

“…Compared to a recent numerical study of parametric amplification in coupled waveguides, also considering wavelength dependency of the coupling strength (Su and Biaggio, 2022), our work provides elegant, practical and easyto-use analytical expressions for the design of an effective dualwaveguide parametric amplifier, accounting for coupling dispersion of an arbitrary order. Considering terms of order greater than 2, both in the single waveguide and in the coupling dispersion, is particularly relevant when the net combined contribution of both single waveguide group velocity and second-order coupling dispersion is close to zero, and there is a need to describe parametric amplifiers operating over a larger bandwidth.…”

Microwave assisted efficient non-degenerate four-wave mixing in pulsed regime

“…Four wave mixing is a well-known nonlinear phenomena which has been studied in diverse systems such as photonic crystals [1,2], optical fiber [3][4][5], atomic medium [6][7][8][9], quantum dot [10,11], superconducting material [12], opto-magnomechanical system [13], bulk media [14] etc. FWM in atomic medium attracts particular interest due to its numerous advantages over other systems.…”