Fiber optic transmitter

• US 6,122,413 A
• Filed: 10/20/1998
• Issued: 09/19/2000
• Est. Priority Date: 10/20/1998
• Status: Expired due to Fees

• Current Assignee: Optigain, Inc. (Fitel Technologies Inc.)
• Original Assignee: Optigain, Inc. (Fitel Technologies Inc.)
• Inventors: Krishnan, Mala, Jiang, Shijun, Bastien, Steven P.
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/175,885
• Time in Patent Office: 700 Days
• Field of Search: 385/1, 385/4, 385/24, 385/12, 385/37, 359/341, 359/177, 359/179, 359/128, 359/180, 359/333, 372/6, 372/102, 372/31, 372/50
• US Class Current: 385/1
• CPC Class Codes: G02B 6/4208 using non-reciprocal elements or birefringent plates, i.e. quasi-isolators optical isolators per se G02F1/093, G02F1/0955
• CPC Class Codes: H04B 10/291 in which processing or amplification is carried out without conversion of the main signal from optical form

Abstract

A fiber optic transmitter provides integrated creation and amplification of a fiber optic signal from a single pump source. A fiber laser is utilized to produce a signal output and a remnant pump output from a single pump source. The remnant pump output is divided out of the signal path while the signal output is modulated and then recombined with the modulated signal output and passed through an erbium doped fiber which absorbs the pump output to amplify the modulated signal output. The output from the fiber laser is input into a first wavelength division multiplexer (WDM) which divides the pump output from the signal output. The first WDM outputs the signal output on a first output trunk and the pump output on a second output trunk. A modulator is connected to the first output trunk of the first WDM for modulating the signal output. A second WDM having a first input connected to the output of the modulator and a second input connected to the second output trunk (pump output) of the first WDM recombines the signal output and the pump output after modulation of the signal output. The recombined signal and pump outputs are then passed through a rare-earth doped fiber to amplify the modulated signal output.

Claims

1. A fiber optic transmitter comprising:

a single longitudinal mode, single polarization fiber laser constructed and arranged to simultaneously have a signal output and a pump output;

a polarization maintaining wavelength division multiplexer (PM WDM) connected to said fiber laser for separating the pump output from the signal output, said PM WDM outputting the signal output on a first output trunk and the pump output on a second output trunk;

a polarization maintaining optical isolator (PM isolator) connected to the first output trunk of the PM WDM;

a modulator connected to the PM isolator;

a first wavelength division multiplexer (WDM) having a first input connected to an output of the modulator, and a second input connected the second output trunk of the PM WDM, said first WDM recombining the signal output and the pump output after modulation of the signal output; and

a rare-earth doped fiber having an input end connected to an output of the first WDM.

2. The fiber optic transmitter of claim 1 further comprising a second WDM having an input connected to an output of the rare-earth doped fiber for separating the pump output from the signal output, said second WDM outputting an amplified modulated signal on a first output trunk and said pump output on a second output trunk.

3. The fiber optic transmitter of claim 2 further comprising an optical isolator having an input connected to said first output trunk of said second WDM.

4. The fiber optic transmitter of claim 3 further comprising an output connector connected to an output of said optical isolator.

5. The fiber optic transmitter of claim 1 wherein said fiber laser comprises a distributed feedback fiber laser.

6. The fiber optic transmitter of claim 1 wherein said fiber laser comprises a distributed Bragg reflector fiber laser.

7. The fiber optic transmitter of claim 1 wherein said modulator comprises an electrooptic modulator.

8. The fiber optic transmitter of claim 1 wherein said modulator comprises a fiber modulator.

9. A multiple-wavelength fiber optic transmitter comprising:

a single longitudinal mode, single polarization pump laser;

a parallel splitter connected to said pump laser for providing first and second pump output channels;

first and second fiber lasers respectively connected to said first and second output channels, said first fiber laser being constructed and arranged to produce a first signal output, said second fiber laser being constructed and arranged to produce a second signal output;

a modulation sub-assembly connected to each of said first and second fiber lasers, each of said modulation sub-assemblies comprising

a polarization maintaining wavelength division multiplexer (PM WDM) connected to said respective fiber laser output for separating the pump output from the respective signal output, said PM WDM outputting said respective signal output on a first output trunk and a pump output on a second output trunk,

a polarization maintaining isolator connected to the first output trunk of the PM WDM;

a modulator connected to the PM isolator,

a first wavelength division multiplexer (WDM) having a first input connected to the modulator, and a second input connected the second output trunk of the PM WDM, said first WDM recombining the respective signal output and the pump output after modulation of the respective signal output, and

a rare-earth doped fiber connected to an output of said first WDM; and

a second WDM having first and second inputs connected to the respective output ends of the rare-earth doped fibers of said modulation sub-assemblies.

10. The multiple wavelength fiber optic transmitter of claim 9 wherein at least one of said fiber lasers comprises a distributed feedback fiber laser.

11. The multiple wavelength fiber optic transmitter of claim 9 wherein at least one of said fiber lasers comprises a distributed Bragg reflector fiber laser.

12. The multiple wavelength fiber optic transmitter of claim 9 wherein at least one of said modulators comprises an electrooptic modulator.

13. The multiple wavelength fiber optic transmitter of claim 9 wherein at least one of said modulators comprises a fiber modulator.

14. The multiple wavelength fiber optic transmitter of claim 9 further comprising a third WDM having an input connected to an output of the second WDM for separating the remnant pump output from the respective signal outputs, said third WDM outputting amplified modulated first and second output signals on a first output trunk and said pump output on a second output trunk.

15. A multiple-wavelength fiber optic transmitter comprising:

a single longitudinal mode, single polarization pump laser;

first and second fiber lasers respectively connected in series to an output of said pump laser, said first fiber laser being constructed and arranged to produce a first signal output, said second fiber laser being constructed and arranged to produce a second signal output;

a first polarization maintaining wavelength division multiplexer (PM WDM) connected to an output of said second fiber laser for separating the pump output from the respective signal outputs, said first PM WDM outputting said respective signal outputs on a first output trunk and a pump output on a second output trunk;

a polarization maintaining isolator connected to the first output trunk of the first PM WDM;

a second PM WDM having an input connected to the PM isolator, said second PM WDM outputting said first signal output on a first output trunk and said second output signal on a second output trunk;

first and second modulators connected respectively to the first and second output trunks of said second PM WDM;

a first WDM having a first input connected to the first modulator, and a second input connected the second modulator, said first WDM recombining said first and second signal outputs;

a second WDM having a first input connected to the output of said first WDM, and a second input connected to the second output trunk of said first PM WDM, said second WDM recombining the first and second modulated signal outputs with the pump output; and

a rare-earth doped fiber connected to an output of said second WDM.

16. The multiple wavelength fiber optic transmitter of claim 15 wherein at least one of said fiber lasers comprises a distributed feedback fiber laser.

17. The multiple wavelength fiber optic transmitter of claim 15 wherein at least one of said fiber lasers comprises a distributed Bragg reflector fiber laser.

18. The multiple wavelength fiber optic transmitter of claim 15 wherein at least one of said modulators comprises an electrooptic modulator.

19. The multiple wavelength fiber optic transmitter of claim 15 wherein at least one of said modulators comprises a fiber modulator.

20. The multiple wavelength fiber optic transmitter of claim 15 further comprising a third WDM having an input connected to the output end of the rare-earth doped fibers for separating the remnant pump output from the first and second signal outputs, said third WDM outputting amplified modulated first and second output signals on a first output trunk and said pump output on a second output trunk.

21. A multiple-wavelength fiber optic transmitter comprising:

a single longitudinal mode, single polarization pump laser;

first and second fiber lasers respectively connected in series to an output of said pump laser, said first fiber laser being constructed and arranged to produce a first signal output, said second fiber laser being constructed and arranged to produce a second signal output;

a polarization maintaining wavelength division multiplexer (PM WDM) connected to an output of said second fiber laser for separating the pump output from the respective signal outputs, said PM WDM outputting said respective signal outputs on a first output trunk and a pump output on a second output trunk;

a polarization maintaining isolator connected to the first output trunk of the PM WDM;

first and second modulators respectively connected in series to the PM isolator;

a first wavelength division multiplexer (WDM) having a first input connected to an output of the second modulator, and a second input connected the second output trunk of said PM WDM; and

a rare-earth doped fiber connected to an output of said first WDM.

22. The multiple wavelength fiber optic transmitter of claim 21 wherein at least one of said fiber lasers comprises a distributed feedback fiber laser.

23. The multiple wavelength fiber optic transmitter of claim 21 wherein at least one of said fiber lasers comprises a distributed Bragg reflector fiber laser.

24. The multiple wavelength fiber optic transmitter of claim 21 wherein at least one of said modulators comprises an electrooptic modulator.

25. The multiple wavelength fiber optic transmitter of claim 21 wherein at least one of said modulators comprises a fiber modulator.

26. The multiple wavelength fiber optic transmitter of claim 21 further comprising a second WDM having an input connected to the output end of the rare-earth doped fibers for separating the remnant pump output from the first and second signal outputs, said second WDM outputting amplified modulated first and second output signals on a first output trunk and said pump output on a second output trunk.