Packaged Optical Add-Drop Filter Based on an Optical Microfiber Coupler and a Microsphere

In this letter, a packaged add-drop filter composed of a silica microsphere resonator with a diameter of
$80~\mu \text{m}$
and an optical microfiber coupler with a waist diameter of 1
$\mu \text{m}$
is investigated. A one-step fabrication process using UV curable epoxy is shown to stabilize the coupling between the microsphere and the microfiber coupler, which is used for the add and drop ports. The packaged microsphere-microfiber coupler device has a high
$Q$
-factor of
$1\times 10^{7}$
in the add–drop filter configuration. This device has excellent features, such as improved ease of fabrication, multiple resonant peaks, and high mechanical stability.