| 摘要 |
PURPOSE:To reduce crosstalk caused depending on the reflected amount between ports and a signal output level difference by applying 1/n distribution or 1/n branching of a signal light after being amplified in advance so as to suppress distribution deviation. CONSTITUTION:A excited light Le from a excitation light source 13 is given to an optical branching device 11 and a signal light Lso is inputted to a signal mode fiber 10 of a low specific refractive index difference DELTA. After the signal light Lso is amplified into a large power by an Er added multi-core fiber 15, the signal is distributed into 1/8 equally by a high DELTA guide path 1X8 star coupler 16. The signal lights LS1 to LS8 to be amplified are outputted respectively from an output terminal of low DELTA single mode fibers 19-1 to 19-8 via high DELTAEr added multi-core fibers 17-1 to 17-8 and output mode field matching regions 18-1 to 18-8. Since matching regions 14, 18-1 are formed between the low DELTAfiber 10 and the high DELTA fiber and between the high DELTA fibers 17-1 to 17-8 and the low DELTA fibers 19-1 to 19-8 respectively, the amplified signal light LS0 is propagated through the optical device without causing the reflection loss. |
