Growth-Induced Birefringence of Bi-Substituted Iron Garnet Films

Investigations into the relation between the growth-induced birefringence (Δn
_f
^G
) and Bi content in Bi garnet films are discussed. BiYMIG (M = Ga, A1) and YIG films were grown by the usual LPE method on {111}GGG substrates. Films with different Bi contents were grown by adjusting the R
₂
(= Fe
₂
O
₃
/M
₂
O
₃
) and Rs (= PbO/Bi
₂
O
₃
) parameters and the growth temperature (T
_G
= 800 to 900°C). The growth- induced birefringence Δn
_f
^G
was obtained by analyzing the dependence of TE-TM conversion efficiency on the light propagation distance. In contrast to θ
_F
, Δ
_n
f
^G
does not depend on the amount of Ga or A1 present. The conclusion was that growth-induced birefringence in this system was due to the inhomogeneous distribution of Bi in the dodecahedral sites.