# US 7,613,398 B2 · Wavelength-tunable light source and wavelength-division multiplexed transmission system using the source

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- Number: US 7,613,398 B2
- Document ID: US7613398B2
- Status: Granted
- Kind: B2
- Application number: 12/004,693
- Filed: 2007-12-21
- Published: 2008-09-25
- Granted: 2009-11-03
- Earliest claimed: 2002-05-03
- Assignees: Korea Advanced Institute of Science and Technology
- Inventors: Chang-Hee Lee; Hyun Deok Kim
- Web page: https://patentgrep.com/patent/US7613398B2

## CPC

- H04B 10/503: {Laser transmitters}
- H04B 10/506: {Multiwavelength transmitters}
- H04B 10/572: Wavelength control
- H04J 14/0307: {Multiplexers; Demultiplexers}
- 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 present invention relates to a wavelength-tunable light source whose output wavelength can be externally controlled and a wavelength-division multiplexed transmission system using the source. A wavelength-tunable light source in accordance with the present invention is constituted to be able to vary the output wavelength of a Fabry-Perot laser diode, that is wavelength-locked to an injected light, by controlling the wavelength of the injected light. A wavelength-tunable light source in accordance with the present invention provides comparatively large output power and excellent economic features. The present invention also presents a wavelength-division multiplexed transmission system using, the wavelength-tunable light source.

## Claims

### Claim 1

A wavelength-division multiplexed transmission system, comprising:
an optical circulator to route a broadband wavelength of light inputted through a first port to a second port and to route an optical signal from N number of Fabry-Perot laser diodes inputted through the second port to a third port;
an N×1 multiplexer/demultiplexer having a common port and N number of input/output ports to transfer optical signals having different wavelengths between the common port and the N number of input/output ports respectively, wherein N represents the number of subscribers connected to the multiplexer/demultiplexer, the N number of Fabry-Perot laser diodes connect to the N number of input/output ports of the multiplexer/demultiplexer respectively, and the common port of the multiplexer/demultiplexer connects to the second port of the optical circulator;
an external modulator having an input port and an output port for optical signals, wherein the external modulator to modulate optical signals inputted through the input port according to electrical signals applied thereto and to pass the modulated signals through the output port; and
an external modulator driving device to provide the electrical signals for operating the external modulator, wherein the third port of the optical circulator couples to the input port of the external modulator, and the external modulator driving device connects to the external modulator.