Miniaturized guided-mode resonance laser based on a one-dimensional finite heterostructure cavity.

Lasers based on the resonant nanostructures have attracted much attention due to their low threshold and compact dimensions. Guided-mode resonance (GMR) structures have been studied in lasing configurations because of their optical field enhancement and convenient free space excitation. However, the GMR inherently requires a larger footprint and is not suitable for high-density packaging. Here, we present numerical evidence of a miniaturized laser implemented in a one-dimensional finite heterostructure cavity (FHC). A GMR resonator and distributed Bragg reflectors are integrated to create the FHC, which enables the efficient coupling and localization of the electric field. Numerical findings indicate that the threshold is approximately 22.5 µJ/cm2, while the emission region is confined within a length of 5.4 µm. In addition, by adjusting the coupling strength, it is capable to achieve controllable lasing emission. The proposed structure provides a compact source for high-capacity optical communications, sensing, and quantum information processing.

Guided-mode resonance sensors with ultrahigh bulk sensitivity and figure of merit assisted by a metallic layer and structural symmetry-breaking.

We propose a refractive index sensor with both high bulk sensitivity and figure of merit (FOM) that engages the guided-mode resonance (GMR) effect with the assistance of a metallic layer and structural symmetry-breaking in the grating layer. Owing to the existence of the metallic layer, the electric field at resonance can be reflected to the sensing environment, and enhanced bulk sensitivity is realized. Meanwhile, the full width at half maximum of the GMR mode can be decreased by increasing the asymmetrical degree of the grating, thus obtaining a high FOM which benefits the sensing resolution. A bulk refractive index sensitivity of 1076.7 nm/RIU and an FOM up to 35889 RIU-1 are achieved simultaneously. Other structural parameters such as the refractive index and fill factor of the grating are systematically discussed to optimize the sensing performance. The proposed GMR sensor with both high bulk sensitivity and FOM value has potential uses in applications with more stringent sensing requirements.

Low-threshold lasing behavior based on quasi-bound states in the continuum in a slanted guided-mode resonance nanocavity.

In this study, hybrid resonance modes are obtained when symmetry-breaking is introduced into a guided-mode resonance (GMR) grating, which transforms bound states in the continuum (BICs) into quasi-BICs with a high-quality factor while retaining the intrinsic GMR mode. The structural parameters are modified such that GMR and quasi-BICs resonance occur at the pump and emission wavelengths of the gain medium, respectively. Resonant optical pumping and high-quality nanocavities are utilized simultaneously, and a low-threshold laser is realized. We theoretically demonstrate that the threshold can be reduced to 24.6 µJ/cm2, which is approximately 4 times lower than that of the laser based on GMR alone. The lasing action can be modulated by optimizing the asymmetry parameter and the electric field, and the threshold can be further reduced.