Birefringence Engineering and High Nonlinearity in Eccentric-Core As$_{2}$ Se$_{3}$ -PMMA Microtapers

A hybrid fiber with an eccentric As
₂
Se
₃
core and a PMMA cladding is tapered to a submicron diameter to achieve ultra high birefringence and a high nonlinearity. The high birefringence is induced by having the As
₂
Se
₃
core eccentric with respect to the circular PMMA cladding symmetry and the high nonlinearity is induced from a tightly confining As
₂
Se
₃
core. Microwires with high group birefringence up to
b
_g
=0.018 and a high waveguide nonlinearity γ = 180 W
^-1
m
^-1
are demonstrated.