Optical Properties of Co-Substituted LPE Magnetic Garnet Films at 1.54 μm

Co-substituted magnetic garnet (YNd)
₃
(CoGeFe)
₅
O
₁₂
thin films were grown by LPE on GGG {111} substrates with the aim of maximizing the magneto-optical properties at 1.5 μm, where absorption loss of optical fibers is minimal. θ
_F
and γ were found to increase as Co content increases. The variation in refractive index (n) at 1.54 μm was much more rapid than at 1.15 μm. Since the value of θ
_F
at 1.15 μm does not depend on the Co content, it was concluded that reduction in n at 1.15 μm was mainly due to reduction in iron ions. A maximum TE
_o
-TM
_o
mode conversion efficiency (F) of 50 percent was obtained at 1.54 μm. This maximum seems to be due to the θ
_F
maximum at 1.54 μm which occurs with Co-substitution. It is to be expected that optimizing birefringence will improve the value of F.