05625481 is referenced by 11 patents and cites 8 patents.

Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission. The separated spontaneous emission component is modulated by being passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, and then, the modulated spontaneous emission component is wavelength-division multiplexed with the main optical signal.

Title
Auxiliary-signal transmission system
Application Number
8/388357
Publication Number
5625481
Application Date
February 14, 1995
Publication Date
April 29, 1997
Inventor
Kazuo Yamane
Kawasaki
JP
Yumiko Kawasaki
Kawasaki
JP
Michikazu Shima
Kawasaki
JP
Tsukasa Takahashi
Sapporo
JP
Hiroyuki Itou
Sapporo
JP
Yuji Tamura
Sapporo
JP
Assignee
Fujitsu
JP
IPC
H04B 10/08
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