Design of a high-Q fiber cavity for omnidirectionally emitting laser with one-dimensional topological photonic crystal heterostructure.

Designing a cavity with a high quality factor for omnidirectionally emitting laser (OEL) can extend its potential applications in optical communication and biomedical detection. We demonstrate a method including five steps to design a high-Q cavity for OEL using a one-dimensional topological photonic crystal heterostructure. A Si/SiO2 fiber cavity for OEL with solid gain medium Er-doped SiO2 is designed following our design steps. The designed fiber can axially transmit the pump energy at low confine loss and act as a cavity for the radial emission of the exited beam, simultaneously. The quality factor of this fiber cavity is on the order of magnitude of 108. Moreover, a method of further improving the Q-factor is proposed. The results in this paper are not restricted to the solid gain medium, and they also can be applied to designing a cavity for optofluidic OEL or quantum dot OEL. Our study may provide not only the reference for OEL manufacture, but also a route for improving the performance of OEL.