Optical: systems and elements – Optical amplifier – Optical fiber
Reexamination Certificate
1999-11-04
2003-03-25
Black, Thomas G. (Department: 3663)
Optical: systems and elements
Optical amplifier
Optical fiber
C385S009000
Reexamination Certificate
active
06538804
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a planar waveguide-type optical amplifier switch which is an optically lossless small switch using optical gain materials directly for the optical switch waveguide along with optical pumping. The present invention provides a solution for the problems occuring in the prior art of optical switches in which the loss of light occurs and the volume of the switch gets larger because an additional optical amplifier is required for compensating the loss of light occurring in conventional optical waveguide-type switch elements used in optical systems such as an optical transmission, an optical distribution system, an optical exchange, and an optical signal processing.
2. Description of the Prior Art
A conventional waveguide-type optical switch used in an optical communication system requires an external optical amplifier to compensate the loss of light and thus is not suitable for an integrated system device in a small compact form. It is therefore an object of the present invention to solve the problem of the optical loss related to the prior art of waveguide-type optical switches and to provide a waveguide-type optical amplifier switch that can be formed in a simply integrated device by using an optical material with an optical amplifying characteristic for the waveguides and by inducing optical amplification of the switched optical signals under an optical pumping.
The present invention is applicable for a key device in optical communication systems, optical switching systems, optical amplifiers, and optical signal processing.
In the prior art there are several technologies, such as electrically controllable optical switches using an electro-optic effect, electrically controllable optical switches using a thermo-optic effect, optically controllable optical switches using an optical control beam, waveguide-type optical amplifiers using an optical pumping, and so on.
Detailed descriptions on the above mentioned prior art will be described referring to the drawings of
FIG. 2
to FIG.
5
.
In the drawings of
FIG. 2
to
FIG. 5
, the numeric
1
represents a wavelength division multiplexing (WDM) optical coupler, the numeric
2
represents a fluorescence emitting ion-doped waveguide, the numeric
3
represents an electrically controllable refractive index varying electrodes, and the numeric
5
represents a general optical waveguide respectively. And L″ represents a waveguide coupling length.
FIG. 2
is a schematic diagram of a conventional planar waveguide-type optical amplifier that does not have a function of optical switch. [Y. Yan and A. J. Faber (EP 0867985), G. E. Blondee et al. (U.S. Pat. No. 5,039,190), Y. C. Yan et al. (Applied Physics Lett., Vol. 71, No 20, pp. 2922-2924, 1997)]. This structure has a defect that it can not provide a switching function because of the lack of an optical switch function in itself.
FIG. 3
is a schematic diagram of a conventional 2×2 electrically controllable planar waveguide-type optical switch that does not have a function of optical amplification. [W. T. Bourd, et al. (U.S. Pat. No. 4,759,595), H Okayama and M. Kawahara (J. Lightwave Technol, Vol. 11, No, 2, pp. 379-387, 1993)]. This structure has a defect that it additionally requires an external optical amplifier to compensate for the loss of the light occurring in an optical switch.
FIG. 4
is a schematic diagram of a conventional 2×2 optically controllable planar waveguide-type optical switch that does not have a function of optical amplification. [M. J. F. Digonnet, et al., (U.S. Pat. No. 5,920,666)]. This structure, likewise the structure in
FIG. 3
, has a defect that it additionally requires an external optical amplifier to compensate for the loss of the light occurring in the optical switch.
FIG. 5
is a schematic diagram of a conventional electrically controllable planar waveguide-type optical switch using Mach-Zehnder interferometer, that does not have a function of optical amplification. This structure, likewise the structure in
FIG. 3
, has a defect that it additionally requires an external optical amplifier to compensate the loss of the light occurring in an optical switch.
That is, because the optical switches of the above mentioned second prior art to the fourth prior art have only the switching functions but have no amplifying functions, they require external optical amplifiers to compensate for the loss of the light occurring in the optical switches, and thereby have difficulty being formed into a compact integrated device. To solve this difficulty or problem, the present invention provides a structure of constituting a waveguide of an optical material that has a characteristic of optical gain to provide an optical amplification function to the switch itself.
Since the waveguide-type optical amplifier using an optical pumping described in the first prior art has only an amplifier but has no switching function, the present invention provides a waveguide amplifier structure having an optical switching function together.
In other words, because the optical switches of the above mentioned second prior art to the fourth prior art have only the switching function without amplifiers and the waveguide-type optical amplifier described in the first prior art has no switching function, there is a defect that, when these devices are being used, each of them should be fabricated independently and be combined to be used, thereby they can not be integrated into a simple compact device. The technical aspect of the present invention is to solve above mentioned problem of the loss of light that had existed in the conventional optical switches and thereby to provide an optical switch element that is more practical and is capable of being integrated in a compact lossless device.
A number of other prior arts includes (1) optical coupler type optical switches composed of active ion doped waveguides with pump controlled differential gain adjustment, [K. J. Blow (U.S. Pat. No. 5,583,957), M. Shigematsu, and K. Nakazato (U.S. Pat. No. 5,136,670)], (2) semiconductor based optical waveguide switches utilizing current-injected gain differences in a gain-guided channel or utilizing voltage-controlled refractive index change and control light absorption wavelength [M. Fujiware (U.S. Pat. No. 4,778,235), S. Nakamura (U.S. Pat. No. 5,329,601), N. Susuki (U.S. Pat. No. 5,754,714)], (3) thermo-optic waveguide switches utilizing a large temperature gradient on heating [N. Ooba, e al. (U.S. Pat. No. 6,122,416)], and (4) wavelength selective optical swithes utilizing grating assisted mode coupling [A. S. Kewitsch, et al. (U.S. Pat. No. 5,875,272)]. Among these prior arts the first and second types of switches can provide optical switching along with optical amplification during the switching functions, but they use different mechanisms from our invention. Operating speed of the first type optical switches are limited by the speed of the pump power change which may not be so fast as that of an all-optical switch using a separate high-speed control light injection just like the one proposed by our invention. The second type of optical switches are optical control type optical switches utilizing voltage applied optical absorption spectrum shifts or utilizing electrical current injected optical gains, while our invention uses optical pumped waveguide gain and optical control type optical switching. The latter two types of the prior arts have only switching mechanisms without optical signal amplification, which are different from our invention. Our invention also proposes potential high-speed optical control optical switches combined with an optical signal amplification function.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a planar waveguide-type optical amplifier switch intended to solve the problems that the prior art have.
To achieve the object, the present invention amplifies an optical signal pa
Ahn Joon Tae
Chang Do Il
Choi Yong Gyu
Jeon Min Yong
Kim Ho Young
Black Thomas G.
Cohen & Pontani, Lieberman & Pavane
Electronics and Telecommunications Research Institute
Hughes Deandra M.
LandOfFree
Planar waveguide-type optical amplifier switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Planar waveguide-type optical amplifier switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Planar waveguide-type optical amplifier switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3026825