Quasi-Phase-Matching Enabled by van der Waals Stacking

TL;DR

This paper demonstrates nanoscale quasi-phase matching using van der Waals stacking of 3R-MoS2, enhancing nonlinear optical processes like second harmonic generation and spontaneous parametric down-conversion for quantum applications.

Contribution

It introduces a novel method of achieving QPM through van der Waals stacking of 3R-MoS2, enabling tunable phase-matching and improved nonlinear optical efficiency.

Findings

Enhanced second harmonic generation beyond non-QPM limits

Improved spontaneous parametric down-conversion efficiency

Tunable phase-matching via stacking orientation

Abstract

Quasi-phase matching (QPM) is a technique extensively utilized in nonlinear optics for enhancing the efficiency and stability of frequency conversion processes. However, the conventional QPM relies on periodically poled ferroelectric crystals, which are limited in availability. The 3R phase of molybdenum disulfide (3R-MoS2), a transition metal dichalcogenide (TMDc) with the broken inversion symmetry, stands out as a promising candidate for QPM, enabling efficient nonlinear process. Here, we experimentally demonstrate the QPM at nanoscale, utilizing van der Waals stacking of 3R-MoS2 layers with specific orientation to realize second harmonic generation (SHG) enhancement beyond the non QPM limit. We have also demonstrated enhanced spontaneous parametric down-conversion (SPDC) via QPM of 3R-MoS2 homo-structure, enabling more efficient generation of entangled photon pairs. The tunable capacity of 3R-MoS2 van der Waals stacking provides a platform for tuning phase-matching condition. This technique opens interesting possibilities for potential applications in nonlinear process and quantum technology.