# Optical nanofiber interferometer and resonator

## TL;DR

This paper presents the fabrication and analysis of optical nanofiber-based interferometers and resonators, introducing a predictive model and identifying a new birefringence source caused by nanofiber ovalization under bending.

## Contribution

It introduces a general linear coupling theory for nanofiber devices and reports a novel birefringence effect due to nanofiber ovalization under bending.

## Key findings

- Successful fabrication of nanofiber interferometer and resonator
- Development of a predictive model for device properties
- Identification of birefringence from nanofiber ovalization

## Abstract

We report the fabrication and characterization of photonic structures using tapered optical nanofibers. Thanks to the extension of the evanescent electromagnetic field outside of the nanofiber two types of devices can be built: a ring interferometer and a knot resonator. We propose a general approach to predict the properties of these structures using the linear coupling theory. In addition, we describe a new source of birefringence due to the ovalization of a nanofiber under strong bending, known in mechanical engineering as the Brazier effect.