Coherent light generators – Optical fiber laser
Reexamination Certificate
1998-07-13
2001-08-14
Font, Frank G. (Department: 2877)
Coherent light generators
Optical fiber laser
C372S006000, C372S102000, C372S034000, C372S096000, C372S101000, C372S099000
Reexamination Certificate
active
06275511
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to the field of optical fiber networks, and more particularly, to multiple fiber Bragg gratings which can be used in optical fiber networks.
In fiber optics, semiconductor lasers provide the only practical source of light signals for optical fiber networks. Narrow linewidth semiconductor laser sources are highly desirable in applications such as WDM (Wavelength Division Multiplexing) networks. In a WDM network, the wavelength of optical signals is used to direct the signals from its source to the desired destination. Hence the narrow linewidths provided by the narrow linewidth semiconductor laser sources allow a large number of communication channels to operate over the network. Narrow linewidth light sources are required, for instance, in a Dense WDM network standard with channels having a separation of 100 GHz frequency (or 0.8 nm wavelength) which the International Telecommunications Union (ITU) has proposed.
One type of laser source is found in U.S. Pat. No. 5,699,377, entitled NARROW LINEWIDTH, STABILIZED SEMICONDUCTOR LASER SOURCE to J. J. Pan, which discloses a narrow linewidth semiconductor laser diode source having a laser diode and a fiber Bragg grating. The laser diode has first and second facets from which output light is emitted. A first end of the fiber Bragg grating is located near the second facet to receive output light from the laser diode. The fiber Bragg grating has a very narrow reflection band about a selected wavelength and reflects output light in a selected narrow linewidth back into the laser diode through its second facet. The output light emitted from the first facet has a very narrow linewidth about the selected linewidth. The entire disclosure of this patent is incorporated herein by reference.
Because laser diode sources are expensive, it is desirable to produce a laser diode source with multiwavelength outputs. To provide multiwavelength outputs of different narrow linewidths, a plurality of fiber Bragg gratings which reflect light at the different wavelengths can be provided near the second facet of the laser diode. Cascading multiple, spaced fiber Bragg gratings in series is more practical than constructing the fiber Bragg gratings in parallel because of the problem of interfacing the input and output light in a parallel structure. Parallel fiber Bragg gratings also require multiple laser diodes. A cascading multiple fiber Bragg gratings structure has certain disadvantages. These include long physical length which requires a long package size and insertion loss due to fusion of the fiber Bragg gratings in series. Moreover, it is difficult to make a temperature compensated package.
SUMMARY OF THE INVENTION
The present invention presents arrangements of multiple fiber Bragg gratings which avoid these problems and disadvantages. In a specific embodiment, multiple fiber Bragg gratings are overlapped with each other at the same location of an optical fiber for reflecting light in a plurality of wavelengths with selected narrow linewidths. The overlapping arrangement provides a compact, efficient structure for reflecting light not only in a multiwavelength laser diode source, but in other applications as well. For instance, the overlapping multiple fiber Bragg gratings of the present invention can be used for making more compact and efficient multiwavelength fiber lasers in a fiberoptic network than those disclosed in U.S. Patent Application entitled, “MULTIWAVELENGTH FIBER LASER SOURCES FOR FIBEROPTIC NETWORKS,” which was filed on Aug. 29, 1997 and assigned Ser. No. 08/920,375. This application is assigned to E-Tek Dynamics, Inc., the assignee of the current application, and is hereby incorporated by reference in its entirety. Examples of other applications of the overlapping multiple fiber Bragg gratings of the present invention include multiwavelength reflector or resonator, wavelength multiplexer/demultiplexer, and optical signal processing.
In accordance with an embodiment of the present invention, an optical fiber section comprises a plurality of fiber Bragg gratings. Each fiber Bragg grating reflects light in a selected narrow linewidth at a different wavelength. At least two of the fiber Bragg gratings overlap each other in the optical fiber section.
In accordance with another embodiment of the invention, an optical fiber section comprises a plurality of fiber Bragg gratings. Each fiber Bragg grating has a selected period so as to reflect light in a wavelength with a selected narrow linewidth. At least two of the fiber Bragg gratings overlap each other in the optical fiber section.
Another embodiment of this invention is directed to semiconductor laser source comprising a laser diode having first and second facets from which output light is emitted. An optical fiber section has a plurality of fiber Bragg gratings. Each fiber Bragg grating reflects light in one of a plurality of wavelengths each with a selected narrow linewidth. At least two of the fiber Bragg gratings overlap each other in the optical fiber section. The optical fiber section has an end proximate the second facet to receive emitted light therefrom and to reflect light in the plurality of wavelengths with the selected narrow linewidths back into the second facet so that output light is emitted from the first facet in the plurality of wavelengths with the selected narrow linewidths.
Yet another embodiment of the invention is directed to a semiconductor laser source comprising a package housing. A first thermoelectric unit and a second thermoelectric unit are mounted to the package housing. A laser diode has first and second facets from which output light is emitted. The laser diode is mounted to the first thermoelectric unit to maintain the laser diode at a predetermined diode temperature. An optical fiber section has a plurality of fiber Bragg gratings. Each fiber Bragg grating reflects light in one of a plurality of wavelengths each with a selected narrow linewidth at a different wavelength. At least two of the fiber Bragg gratings overlap each other in the optical fiber section. The optical fiber section has an end proximate the second facet to receive emitted light therefrom and to reflect light in the plurality of wavelengths with the selected narrow linewidths back into the second facet so that output light is emitted from the first facet in the plurality of wavelengths with the selected narrow linewidths. The optical fiber section is mounted to the second thermoelectric unit to maintain the optical fiber section at a predetermined fiber temperature.
REFERENCES:
patent: 5208876 (1993-05-01), Pan
patent: 5317576 (1994-05-01), Leonberger et al.
patent: 5699377 (1997-12-01), Pan
patent: 5812712 (1998-09-01), Pan
patent: 5844927 (1998-12-01), Kringlebotn
patent: 6018534 (2000-01-01), Pan et al.
patent: 6044093 (2000-03-01), Ventrudo et al.
R.W. Fallon, “Multiplexed Identical Braod-Band-Chirped Grating Interrogation system for Large-Strain Sensing Application” Dec. 1997, IEEE Photonics Technology Latter, vol. 9, No. 12, Pag. 1616-18.*
Y. Zhao, “A Novel Bidirectional Add/Drop Module Using Waveguide Grating Routers and Wavelength Channel Matched Fiber Gratings”, Sep. 1999, IEEE Photonics Latters, vol. 11, No. 9, Pag 1180-82.*
U.S. application No. 08/920,375, Pan et al., filed Aug. 29, 1997.
Ball et al., “Nd3+Fibre Laser Utilising Intra-Core Bragg Reflectors,”Electronics Letters(1990) 26:1829-1830.
Kashyap et al., “All-Fibre Narrowband Reflection Gratings at 1500 nm,”Electronics Letters(1990) 26:730-731.
Ball et al., “Standing-Wave Monomode Erbium Fiber Laser,”IEEE Photonics Technology Letters(1991) ??:613-615.
Sejka et al., “Distributed feedback Er3+-doped fibre laser,”Electronics Letters(1995) 31:1445-1446.
Agrawal,Nonlinear Fiber Optics,Second Edition, Chapter 12, pp. 539-540, Academic Press, (1995).
Pan Jing-Jong
Shi Yuan
E-Tek Dynamics
Flores Ruiz Delma R.
Font Frank G.
Townsend and Townsend / and Crew LLP
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