Manufacture of 3-D microfiber coil resonators

Three-dimensional microfiber coil resonators are experimentally demonstrated in air. Two-turn, three-turn, and four-turn microcoil resonators are fabricated by wrapping a microliber on a low refractive index rod. The extinction ratio and free spectrum range are similar to 10 dB and similar to 1 nm, respectively. The spectrum optimization by the tuning of the pigtails is investigated.