Optical waveguides – With optical coupler – Input/output coupler
Reexamination Certificate
1999-09-17
2001-11-13
Healy, Brian (Department: 2874)
Optical waveguides
With optical coupler
Input/output coupler
C385S031000, C385S024000, C385S123000, C359S199200, C359S199200
Reexamination Certificate
active
06317539
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to optical waveguide grating devices and, more particularly, to such devices with interleaved sampled and chirped gratings which might be especially useful in WDM networks.
In optical waveguide grating devices, the medium of the waveguide through which light signals are transmitted is periodically or nearly periodically modulated to reflect the light signals at particular wavelengths. Though optical waveguides appear in different forms, such as waveguide-bearing substrates, the fiber Bragg grating has been the recent focus of much development. Hence while the present invention is described in terms of fiber Bragg gratings, it should be understood that much, if not all, of the aspects of the present invention are adaptable to other types of optical waveguide grating devices as well.
Fiber Bragg gratings, and other optical waveguide gratings, are key components in many fiberoptic and telecommunications systems. In fiberoptic telecommunications, gratings can be used for many functions, such as filtering, multiplexing/demultiplexing, and gain equalization in broadband WDM (Wavelength Division Multiplexed) systems where the wavelength of an optical signal is used to direct the signal through a network system to its intended destination. The optical signals of a particular wavelength define a communication channel over the network. In advanced WDM network systems, such as DWDM (Dense WDM) systems, the wavelength spacing for communication channels is much tighter, i.e., narrower, so that more channels can used for a given amount of bandwidth in the network, than in standard WDM networks. DWDM wavelength spacing between channels is set at 0.8 nm (100 GHz) and more recent efforts are directed at channel spacings of 0.4 nm (50 GHz). For the purposes of this application, the terms, “WDM” and “WDM networks,” are used broadly to include DWDM and DWDM networks unless stated otherwise.
Gratings are furthermore useful in dispersion compensation, especially for long-distance transmissions. The role of such gratings is expected to expand even more as improvements are made in their design and manufacture.
The present invention provides for such improvements in filtering, multiplexing/demultiplexing, and equalization functions for gratings, and even in compensation for second-order signal dispersion.
SUMMARY OF THE INVENTION
The present invention provides for an optical waveguide device comprising a plurality of sampled fiber Bragg gratings which are interleaved together. Each of the sampled fiber Bragg gratings has a grating period which differs from the others so to produce a predetermined reflection spectrum for the optical waveguide device. By making the sample periods for the fiber Bragg grating different from each other, the resulting reflection spectrum has missing reflection peaks. A bandpass filter can be effectively created.
The present invention further provides for an optical waveguide device comprising a sampled fiber Bragg grating with a grating period which varies discretely at intervals along the optical fiber so as to produce a more uniform reflection spectrum for the optical waveguide device.
Finally, the present invention provides for an optical waveguide grating device comprising a sampled and chirped fiber Bragg grating in an optical fiber. The fiber Bragg grating is sampled by a chirped sampling function. With the optical waveguide device coupled to a transmission optical fiber, the sampling function and the chirp of the sampling function can be selected so that a resulting dispersion slope of the optical waveguide device matches a dispersion slope of the transmission optical fiber so as to compensate for signal dispersion caused by the dispersion slope of the transmission optical fiber.
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Loh Wei-Hung
Pan Jing-Jong
Zhou Feng-Qing
Greene Kevin E.
Healy Brian
JDS Uniphase Corporation
Lacasse Randy W.
Lacasse & Associates
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