Influence of longitudinal mode components on second harmonic generation in III-V-on-insulator nanowires

Abstract

The large index contrast and the subwalength tranverse dimensions of nanowires induce strong longitudinal electric field components. We show that these components play an important role for second harmonic generation in III-V wire waveguides. To illustrate this behavior, an efficiency map of nonlinear conversion is determined based on full-vectorial calculations. It reveals that many different waveguide dimensions and directions are suitable for efficient conversion of a fundamental quasi-TE pump mode around the 1550 nm telecommunication wavelength to a higher-order second harmonic mode.

Efficient type II second harmonic generation in an indium gallium phosphide on insulator wire waveguide aligned with a crystallographic axis

“…It was previously studied in AlGaAs photonic wires with low vertical confinement [10], where the modes are well approximated by transverse waves. As we recently demonstrated for the case of type I SHG, more complex wave mixing involving the longitudinal components can be expected in III-V-on-insulator wire waveguides [11,12]. We hence apply the same vectorial analysis to the case of type II phase matching to identify efficient nonlinear couplings between a pump around 1550 nm and a higher-order mode around 775 nm.…”

“…We connect the markers corresponding to the same SH higher-order mode with a line. Interestingly, and in contrast to type I SHG [12], the most efficient conversion occurs for relatively thick waveguides (605 nm wide, 295 nm high) aligned with a main crystallographic axis [κ max = i3500 (W 1/2…”

“…• m) −1 [12]. The higher efficiency for type II SHG can be understood by analyzing the expression of the effective nonlinearity for waves propagating along a crystallographic axis of a III-V material.…”

Efficient Type II Second Harmonic Generation in an Indium Gallium Phosphide on insulator wire waveguide aligned with a crystallographic axis

“…It was previously studied in AlGaAs photonic wires with low vertical confinement [10], where the modes are well approximated by transverse waves. As we recently demonstrated for the case of type I SHG, more complex wave mixing involving the longitudinal components can be expected in III-V-on-insulator wire waveguides [11,12]. We hence apply the same vectorial analysis to the case of type II phase matching in order to identify efficient nonlinear couplings between a pump around 1550 nm and a higher order mode around 775 nm.…”

Generalization of Second-Order Quasi-Phase Matching in Whispering Gallery Mode Resonators Using Berry Phase

“…For the sake of simplicity, we will make the approximation that TM modes feature only a non-zero z component of the electric field, so that only the TE modes will show a TSAM character. Going beyond this approximation, the full-vectorial model of NL processes even opens more possibilities to the present theory as suggested by Ciret et al 28 While describing the mode profiles of the WGM, it straightforwardly comes that a frame following the symmetry of the system such as the rotating one (|𝑟⟩, |𝜑⟩, |𝑧⟩) is more convenient than the fixed cartesian one (|𝑥⟩, 𝑦⟩, |𝑧⟩) as shown in Figure 1. Most theoretical works, from basic theory of WGMs to advanced derivation of NL quasi-phase matching have used this rotating frame.…”