Modification of visible spontaneous emission with silicon nitride photonic crystal nanocavities

Abstract

Photonic crystal (PC) nanocavities based on silicon nitride membranes are studied as tools for the manipulation of spontaneous emission in the wavelength range between 550 nm and 800 nm. We observe a strong modification of the fluorescence spectrum of dye molecules spin-cast on top of the PC, indicating an efficient coupling of the dye emission to the cavity modes. The cavity design is optimized with respect to the quality factor and values of nearly 1500 are achieved experimentally. Taking into account the small mode volume, which leads to a strong Purcell enhancement, these nanocavities enable the realization of efficient single photon sources in the visible region of the spectrum. Furthermore, their fabrication is fully compatible with existing CMOS technology, making an integration into more complex optoelectronic devices feasible.

Gallium phosphide photonic crystal nanocavities in the visible

“…However, these Q's can still enable a significant Purcell effect, up to 185, as mode volume is only 0.7͑ / n͒ 3 . While these quality factors are similar to those measured at visible wavelengths in optimized structures with lower index contrast, 13 improving fabrication and using modified designs with simulated Q values more than a order of magnitude higher 24 should yield structures with much higher Q. Additionally, a wider photonic band gap allows more flexibility in cavity design, is more robust to fabrication variations, and is more suitable for any experiments in which the undercut structures are back filled with a low index material. 25 The shortest resonant cavity wavelength observed at room temperature was 645 nm with a quality factor of 610.…”

“…12 Low refractive index is also the main drawback of the silicon nitride system. 13,14 Chen et al 15 and Zhang et al 16 have fabricated AlGaInP-based photonic crystals in the red with InGaP quantum wells. This system, however, requires precise control over the fraction of each material in the quaternary system to obtain the proper band gap and lattice constant, and is lattice matched to a GaAs substrate, which is absorbing in the visible.…”

Photonic Crystal and Plasmonic Silicon-Based Light Sources

“…1(c)]. Barth et al [26] show that nonvertical etch profile is especially detrimental to cavity Q factors.…”

High-Quality Confinement of Visible Light in Disordered Photonic Crystal Waveguides in the Anderson-Localized Regime

“…The development of efficient optical cavities operating at visible wavelengths is particularly important for the study of cavity quantum electrodynamics effects with defect centers in diamond and twodimensional (2D) materials, and to control and boost the emission dynamics of organic molecules and colloidal quantum dots. Engineered 2D photonic crystal cavities in silicon nitride, however, have shown quality factors limited to values of the order of 1000 [2,3]. Such low confinement efficiencies, compared to longer wavelength devices, can mostly be attributed to losses due to fabrication imperfections that are difficult to avoid when dealing with the small features required to trap visible light on a nanophotonic chip.…”