Power source for a dispersion compensation fiber optic system
View Patent ↗This invention generally relates to an optical filter for a fiber optic communication system. An optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.
1. A fiber optic communication system, comprising:
an optical signal source adapted to produce a partially frequency modulated signal; and
an optical discriminator adapted to convert the partially frequency modulated signal into a substantially amplitude modulated signal, where the optical discriminator is adapted to compensate for at least a portion of a dispersion in a transmission fiber.
2. The system according to claim 1 , where the optical signal source is a single wavelength semiconductor laser.
3. The system according to claim 2 , where the single wavelength semiconductor laser is a distributed feed back laser.
4. The system according to claim 3 , where the single wavelength semiconductor laser includes a distributed Bragg reflector (DBR) section, a gain section, and a phase section.
5. The system according to claim 4 , further including a combiner that combines outputs from a driver and a dc current source, where the driver provides a modulated signal and the dc current source provides a dc bias current, where the combiner combines the modulated signal and the dc bias signal to provide a summed signal.
6. The system according to claim 5 , where the summed signal is provided to the gain section to produce a partially frequency modulated signal above its threshold level.
7. The system according to claim 5 , where the summed signal is provided to the DBR section to produce a partially frequency modulated signal.
8. The system according to claim 3 , where the summed signal is provided to the phase section.
9. The system according to claim 2 , where the single wavelength semiconductor laser is a vertical cavity surface emitting laser.
10. The system according to claim 1 , where the optical signal source is an externally modulated.
11. The system according to claim 10 , where the optical signal source includes a continuous wave laser and a phase modulator.
12. The system according to claim 10 , where the phase modulator is a semiconductor modulator.
13. The system according to claim 10 , where the phase modulator is a LiNbO 3 modulator.
14. The system according to claim 10 , where the phase modulator is a semiconductor optical amplifier.
15. The system according to claim 1 , where the optical signal source is a tunable semiconductor laser.
16. The system according to claim 15 , where the tunable semiconductor laser is a sampled grating distributed bragg reflector (SGDBR) laser.
17. The system according to claim 16 , where the SGDBR laser includes a sampled grating in a rear section, a gain section, a phase section, and a sampled grating in a front section, where a summed signal includes a bias current signal and modulated signal that is fed to the gain section to produce the partially frequency modulated signal.
18. The system according to claim 15 , where the tunable semiconductor laser is a distributed Bragg reflector laser.
19. The system according to claim 1 , where the optical discriminator is a Bragg grating.
20. The system according to claim 19 , where the Bragg grating is formed in a fiber.
21. The system according to claim 19 , where the Bragg grating is formed in a planar waveguide.
22. The system according to claim 1 , where the optical signal source is a directly modulated laser.
23. The system according to claim 22 , where the directly modulated laser is adapted to produce signals with a 2-7 dB extinction ratio.
24. The system according to claim 1 , where the optical discriminator is a thin film filter.
25. The system according to claim 24 , where the optical discriminator is formed by a transmission edge of the thin film filter.
26. The system according to claim 1 , further including a combiner that combines outputs from a driver and a dc current source, where the driver provides a modulated signal and the dc current source provides a dc bias current, where the combiner combines the modulated signal and the dc bias signal to provide a summed signal to directly modulate the optical signal source above its threshold and modulate its gain.
27. The system according to claim 1 , where the optical discriminator has a positive slope.
28. The system according to claim 1 , where the optical discriminator has a negative slope.
29. The system according to claim 1 , where the optical discriminator is formed by cascading a number of non-interfering multicavity thin film filters.
30. The system according to claim 1 , where the optical discriminator is formed by a coupled multi-cavity filter.
31. The system according to claim 1 , where the optical discriminator operates in reflection.
32. The system according to claim 1 , where the optical discriminator operates in transmission.
33. The system according to claim 1 , where the optical discriminator is a periodic filter.
34. The system according to claim 1 , where the optical discriminator is a multi-cavity etalon that has an associated dispersion D d that has the opposite sign to a dispersion D f of the transmission fiber at a multiplicity of equally spaced wavelengths.
35. The system according to claim 1 , where the optical discriminator is a series of cascaded etalon filters.