A packaged whispering gallery resonator device based on an optical nanoantenna coupler

TL;DR

This paper introduces a packaged whispering gallery mode device utilizing an optical nanoantenna coupler and a glass microsphere, achieving high Q-factors and low-threshold lasing for practical applications.

Contribution

The work presents a novel integrated packaged WGM device with nanoantenna coupling, high Q-factor, and low lasing threshold, enabling practical use in lasers, filters, and sensors.

Findings

Achieved a Q-factor of approximately 10^8.

Demonstrated a low lasing threshold of 93 μW at 1531 nm.

Provided environmental isolation and unidirectional coupling in a compact package.

Abstract

In this work, we present the design and fabrication of a packaged whispering gallery mode (WGM) device based on an optical nanoantenna as the coupler and a glass microsphere as the resonator. The microspheres were fabricated from SiO$_2$ fiber or Er$^{3+}$-doped fiber, the latter creating a WGM laser with a threshold of 93 $\mu$W at 1531 nm. The coupler-resonator WGM device is packaged in a glass capillary. The performance of the packaged microlaser is characterized, with lasing emission both excited in and collected from the WGM cavity via the nanoantenna. The packaged system provides isolation from environmental contamination, a small size, and unidirectional coupling while maintaining a high quality (Q-) factor ($\sim$10$^8$). It opens up new possibilities for practical applications of WGM microdevices in a variety of fields such as low threshold lasers, filters, and sensors.