# US 6,295,147 B1 · Wavelength multiplexing transmission apparatus and wavelength demultiplexing reception apparatus

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- Number: US 6,295,147 B1
- Document ID: US6295147B1
- Status: Granted
- Kind: B1
- Application number: 09/115,914
- Filed: 1998-07-15
- Granted: 2001-09-25
- Earliest claimed: 1997-10-17
- Assignees: Fujitsu Limited
- Inventors: Kazuo Yamane; Takashi Tsuda; Yumiko Kawasaki; Satoru Okano
- Web page: https://patentgrep.com/patent/US6295147B1

## CPC

- H04B 10/506: {Multiwavelength transmitters}
- H04B 10/564: Power control
- H04B 10/572: Wavelength control
- H04J 14/03: {WDM arrangements (ADM arrangements H04J14/0202; WDM network architectures H04J14/0278)}
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

The invention provides a wavelength multiplexing transmission apparatus includes a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other, and a wavelength multiplexing section for wavelength multiplexing the optical signals outputted from the optical signal outputting sections and sending out a resulting optical signal. Each of the optical signal outputting sections includes a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength, and a wavelength filter capable of passing therethrough and sending out only an optical signal of the predetermined wavelength to be outputted from the transmission light source to prevent a wavelength drift of the optical signal outputted from the transmission light source. A variation of the wavelength of the transmission light source is detected, and the transmission light source is shut down in order to prevent otherwise possible crosstalk with another channel and prevent a further influence of the same.

## Claims

### Claim 1

A wavelength multiplexing transmission apparatus comprising:
a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other; and
a wavelength multiplexing section, connected to said plurality of optical signal outputting sections, for multiplexing the optical signals outputted from said plurality of optical signal outputting sections and transmitting the multiplexed optical signal;
wherein each of said optical signal outputting sections includes:
a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength,
a wavelength filter, connected to said transmission light source, for receiving the optical signal and allowing an optical signal with the predetermined wavelength to pass through and outputting the optical signal with the wavelength to prevent a crosstalk caused by a wavelength drift of the optical signal outputted from said transmission light source,
a first abnormal condition detecting section, connected to said wavelength filter, for detecting an abnormal condition of an output level of the optical signal passed through said wavelength filter by monitoring whether a level of the optical signal passed through said wavelength filter is lower than a first threshold level set in advance, and
a second abnormal condition detecting section, connected to said transmission light source, for detecting an abnormal condition of an output level of the optical signal outputted from said transmission light source, and
a third abnormal condition detecting section, connected both to said first abnormal condition detection section and said second abnormal condition detection section, for detecting an abnormal condition of a wavelength of the optical signal outputted from said transmission light source when an abnormal condition is detected by said first abnormal condition detecting section and a normal condition is detected by said second abnormal condition detecting section.