[54] LIGHT SIGNAL RECEPTION APPARATUS HAVING AN IMPROVED LIGHT SURGE ELIMINATING FUNCTION
[75] Inventor: Terumi Chikama, Kawasaki, Japan
[73] Assignee: Fujitsu Limited, Kanagawa, Japan
[21] Appl. No.: 658,944
[22] Filed: May 31,1996
[30] Foreign Application Priority Data
Jim. 5, 1995 [JP] Japan 7-137597
[51] Int CL6 HOIS 3/00
[52] U.S. CI 359/341; 359/161; 359/177
[58] Field of Search 359/161, 177,
359/337, 341
[56] References Cited
U.S. PATENT DOCUMENTS
5,317,660 5/1994 Vieth 385/24
5,436,760 7/1995 Nakabayashi 359/341
■■iiiiiMimii
US005701195A [li] Patent Number: 5,701,195 [45] Date of Patent: Dec. 23, 1997
5,504,608 4/1996 Neeves et al 359/124
5,552,919 9/1996 Majima et al 359/161
Primary Examiner—-Mark Hellner
Attorney, Agent, or Firm—Helfgott & Karas, P.C.
[57] ABSTRACT
In a light signal reception apparatus having a light surge eliminating function and provided in an optical transmission system, the apparatus of the present invention can effectively eliminate a light surge accidentally included in a light signal. The apparatus includes: an optical amplifying unit for receiving a light signal and amplifying it to a predetermined level; an optical filtering unit operatively connected to the optical amplifying unit for eliminating the light surge and passing through the light signal; an opto-electrical converting unit operatively connected to the optical filtering unit for converting the light signal to an electrical signal; and a monitoring unit operatively connected to the optical amplifying unit for monitoring a fluctuation of the light signal, and controlling a transmission wavelength characteristic of the optical filtering unit or a wavelength of the light signal in order to eliminate the light surge.
10 Claims, 11 Drawing Sheets
