Improved Q-factors of III-nitride-based photonic crystal nanocavities by optical loss engineering

Abstract

III-nitride-based two-dimensional photonic crystal (2D-PhC) cavities with high-quality factors (Q-factors) have a large potential application, however realized Q-factors in the visible wavelength regime have been relatively moderate. In this study, we demonstrate the design and fabrication of 2D-PhC cavities to achieve high Q-factors, especially in the visible range. From the comparison of numerical calculations and the experimental results, we discuss the dominant optical losses that limit the Q-factor of H3-type cavities formed in an Eu,O-codoped GaN film. Based on these results we designed 2D-PhC cavities which can effectively suppress these dominant losses. We fabricated 2D-heterostructures and show a high Q-factor of 10500 at a resonant wavelength of ∼660 nm, which is considerably larger than any existing GaN-based nano/micro-resonators in the visible region. This study provides design guidelines for the realization of high Q-factors in photonic crystal nanocavities based on III-nitride semiconductors.

Perspectives for III-nitride photonic platforms

“…Numerous developments were dedicated to photonic crystal cavities as they can provide small mode volumes and a testbed for cavity quantum electrodynamics [107]. Despite the efforts provided by the community, the quality factors of two-dimensional photonic crystal cavities or one-dimensional nanobeam cavities have remained below their theoretical values [108][109][110][111][112][113][114][115][116][117][118][119][120]. It did not prevent reporting the demonstration of high-performance single devices from vertical-emitting photonic crystal lasers [121,122], watt-class photonic crystal lasers [123] or high-β values nanobeam lasers [124].…”

Mode analysis of GaN two-dimensional photonic crystal nanocavities undercut by photo-electrochemical etching

“…34) Towards improvement of the Q-factors, fabrication methods have been studied for III-N semiconductor photonic crystal cavities. [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] One of the main difficulties arises from the high inertness of III-N semiconductors, which hinders undercut etching to form air-suspended photonic crystal cavity slabs by simple chemical etching. Among various undercut methods studied so far, bandgap selective photo-electrochemical (PEC) etching of InGaN-based sacrificial layers is a well-known method for the fabrication of GaN photonic crystal cavities.…”

Room temperature optical coupling of neodymium ions to photonic crystal L3 cavity in gallium nitride semiconductor

“…The well-developed GaN semiconductor platform allows integration of Ln ions into more complex devices, which holds the promise of unlocking new opportunities for the advancement of quantum technologies. 33) Nevertheless, despite the fact that Ln-doped GaN materials and devices have been studied for more than two decades, 27) only a limited number of studies have been conducted on the optical coupling of Ln ions to GaN nanostructures 34,35) and PhC nanocavities [36][37][38] for the purpose of enhancing the photon emission rate and the photon extraction efficiency.…”