MXPA97010244A - Opt switch selector - Google Patents

Abstract

The present invention relates to a gain-switched optical selector, which is achieved by employing an optical amplifier of adulterated fiber with rare earth as the switching element per se. Each of the optical amplifiers of fibers adulterated with rare earths, acts as an ON / OFF switch. Also, the optically switched gain selector of this invention is a natural complement in optical communication systems amplified optically today. In one embodiment, this is achieved by employing a pump selector circuit, in conjunction with a plurality of pumps and a plurality of fiber optic amplifiers adulterated with rare earths. The particular pump and the corresponding optical amplifier is chosen by use of a verification structure, to determine which signal is to be selected and directed to an output. In another embodiment, a so-called tuned pump structure is employed in conjunction with a plurality of filters and a corresponding plurality of optical amplifiers of fibers adulterated with rare earths. A pump tuning structure is employed to control the tunable pump in order to select the appropriate optical power signals at any of a plurality of determined wavelengths.

Description

OPTICAL SWITCH SELECTOR The patent applications of the U.S.A. Serial No. 08/777894 (MT Fatehi-WH Knox Case 15-20), Serial No. 08/777890 (MT Fatehi-WH Knox Case 12-17) and Serial No. 08/777892 (MT Fatehi-WH Knox Case 18-23), were presented concurrently with this. Ca-apo Technician This invention relates to elements of optical communications and more specifically to optical selector switches. BACKGROUND An electric Nxl selector switch is a Nxl switching device that directs any of the N supply lines to the single output port as illustrated in FIGURE 1. An optical Nxl selector switch is the optical analog of the Nxl electric selector switch, in where input and output ports are optical fibers that carry one or more optical communication signals at different wavelengths. Certain selector switches can allow selection of more than one power port and add (under certain rules) the signals from the selected ports. This is properly called the pickup capacity of the selector switch. REF: 26188 Previous known selectors use mechanical switching elements. These previous structures that employ mechanical selectors were limited to select only one line at a time, their speed was slow and their reliability was less than convenient. Such a structure is illustrated in FIGURE 1, wherein a plurality of input optical lines 100-1 to 100-N are provided to the selector 101 and switching element 103. The switching element 103 under control of an actuator 102, it will then choose one of the optical lines 100 to be supplied to the optical output line 104. A number of electromechanical optical selector switches are currently available. These devices are based on mechanically moving the input and / or output fibers or using various reflective or deflecting optical elements to align light beams outside the feed fibers and direct them to the output fiber. Clearly, these mechanical switches are slow and in most cases do not allow collection capacity, a convenient feature in communications systems. In some cases, the optical loss associated with these elements is significant. Lithium niobate-based solid state waveguide selector switches (see for example US Patent No. 5,181,134) or indium phosphide optical switching devices are also available, which resolve the speed problems. The disadvantage involved with these optical switching devices includes polarization dependence and significant optical losses. The large losses of optical insertion connected to these devices soon become intolerable, when said devices are concatenated. SUMMARY OF THE INVENTION The problems and limitations of the mechanical selectors of the prior art and various solid state optical selectors are overcome in one embodiment of the invention, by employing an optical fiber amplifier adulterated with optical rare earth, such as the switching element. per se of an optical gain switch. Each of the optical amplifiers of fibers adulterated with optical rare earths acts as an ON / OFF switch. Also, the switched-gain optical selector of this invention is a natural complement in optical communication systems currently optically amplified. In one embodiment, this is achieved by employing a pump selector circuit in conjunction with a plurality of pumps and a plurality of fiber optic amplifiers adulterated with corresponding rare earths. The particular pump and the corresponding optical amplifier are chosen by use of a monitor structure to determine which signal is to be selected and directed to an output. In another embodiment, a so-called tuned pump structure is employed, in conjunction with a plurality of filters and a corresponding plurality of optical amplifiers of fibers adulterated with rare earths. A pump tuning structure is employed to control the tuneable pump in order to choose the appropriate one of a plurality of optical power signals at any of a plurality of determined wavelengths.

FIGURE 1 is an electromechanical selector structure of the prior art; FIGURE 2 illustrates one embodiment of the invention employing so-called switched pumps, with optical fiber amplifiers adulterated with rare earths; FIGURE 3 illustrates a tuned pump structure that includes optical amplifiers of optical fibers adulterated with rare earths; and FIGURE 4 illustrates a switch pump structure including a plurality of bombs and amplifiers of adulterated fibers with corresponding rare earths. Detailed Description FIGURE 2 shows in simplified form, one embodiment of the invention that includes fiber optic lines 201 and 202 that supply optical signals at pre-determined wavelengths or wavelength arrays to optical amplifier of rare-earth-adulterated fibers (hereinafter "amplifier") 203 and amplifier 204, respectively. The optical fiber adulterated with rare earth, for example, may be a section of erbium-adulterated fiber coupled to a wavelength selective coupler, for example a wavelength-splitting hardened coupler through which a pump is coupled. It should also be noted that the loss is compensated by the stretch of fiber adulterated with rare earth, and the gain is compensated by the energy of the pump. As illustrated, the pump 205 is coupled to the amplifier 203 and the pump 206 is coupled to the amplifier 204. As is known in the art, each of the pumps 205 and 206 respectively energizes the amplifiers 203 and 204. Additionally, it is known that pumping can be co-directional or directional counter. Without doubt, pumping can also be bi-directional. The outputs of the amplifiers 203 and 204 are combined by an optical star coupler (hereinafter "coupler") 207 in a well-known manner. The coupler 207 for a structure of two optical lines is known as a coupler of 3dB. The primary output of the coupler 207 that supplies the output optical fiber 211, which can be connected to a receiver or a long distance transport fiber. The secondary output of the coupler 207 is supplied to an optical to electrical (O / E) converter 208, which verifies the energy level of the selected line and determines the parameters and ID (identification) labels associated with selected lines (see for example US patent application co-pending Serial No. 08/579529, filed on December 27, 1995). The O / E information 208 is supplied to the pump selector 209, which then selects either the pump 205 or the pump 206 according to the desired parameters. It should be noted, however, that other optical coupling structures known in the art can likewise be used instead of coupler 207. This will be apparent to those skilled in the art. It will be noted that the secondary output from the coupler 207 that is supplied to the O / E 208 is optional and this embodiment of the invention can be used without it. The output of the O / E 208 is supplied to the pump selector circuit 209, where it is used to further refine the pump selection process. Specifically, in this example the O / E 208 verifies the energy level of the selected signal and determines the parameters and ID tags associated with the selected line (s) supplied to the coupler 207. Also supplied to the pump selection circuit 209 is information of commands and control from the command and control unit 210, which is used with information from other network elements in an optical system, in order to choose which of the pumps 205 and 206 will be selected and in accordance when the amplifiers 203 and 204 are selected. will supply in an optical signal coupler 207 to the output optical fiber 211 as an output. It should be noted, however, that although we have shown the use of O / E 208 in this example, other structures may be used to verify different parameters in order to choose which of the pumps 205 and 206 and in accordance with which of the amplifiers 203 and 204 will be supplied at the exit. FIGURE 3 shows in simplified form another embodiment of the invention for a plurality of optical fiber lines 301-1 to 301-N and a corresponding plurality of rare amplifiers 302-1 to 302-N. In this embodiment of the invention, only one tunable pump 308 is used, which is coupled to each of the filters 303-1 to 303-N through the optical star coupler (hereinafter "coupler") 309 which gives us the technical advantage of cost savings . The plurality of filters 304-1 to 304-N are associated in a one-to-one basis with amplifiers 303-1 to 303-N, respectively. Again, the outputs of the amplifiers 302-1 to 302-N are supplied to the optical star coupler (hereinafter "coupler") 304. The primary output of the coupler 304 provides the output of the system and is supplied to the optical fiber of output 310, which can be connected to a receiver or a long-distance transport fiber. The secondary output of the coupler 304 is supplied to an energy verification unit 305, which checks the energy level of the selected line and determines the parameters and ID (identification) labels associated with selected lines (see for example the patent application of the US co-pending Serial No. 08/579529 previously noted). The O / E 305 information is supplied to the pump tuning circuit 306, which then chooses one of the pumps 303-1 through 303-N according to the desired parameters. It should be noted, however, that the other optical coupling structures known in the art can equally be used instead of the coupler 304. It should be noted, however, that although we have shown the use of O / E 305 in this example, other structures can used to check different parameters in order to adjust the pump tuning circuit 306 and hence the tunable pump 308 and in accordance which of the amplifiers 302-1 to 302-N will be supplying the output. This will be apparent to those with skill in the specialty. It will be noted that this secondary output of the coupler 304, which is supplied to O / E 308 is optional and this embodiment of the invention can be employed without it. The output of the O / E 305 is supplied to the pump tuning circuit 306 where it is used to further refine the pump selection process. Specifically, in this example O / E 305 checks the energy level of the selected signal and determines the parameters and ID tags associated with the selected line (s) that are supplied to the coupler 304. Pump tuning circuit 306 is also supplied. of control and commands from the command and control unit 307, which is used with information from other network elements in an optical system, in order to choose which wavelength is to be selected and according to which one of the amplifiers 302- 1 to 302-N will supply an optical signal through the coupler 304 to the output optical fiber 310 as an output. The output of the tunable pump 308 is supplied by the coupler 309 to the filters 303-1 to 303-N which, in turn, choose the appropriate one of the amplifiers 302-1 to 302-N to supply an output to the coupler 304. FIGURE 4 shows in simplified block diagram form, another embodiment of the invention employing a plurality of optical fiber lines 401-1 to 401-N and a corresponding plurality of rare-earth optical fiber amplifiers (below) amplifiers ") 402-1 to 402-N. In this embodiment of the invention, a corresponding plurality of pumps 403-1 to 403-N are associated with amplifiers 402-1 to 402-N respectively. The optical outputs from the amplifiers 402-1 to 402-N in this example are supplied to an optical star coupler (hereinafter "coupler"). It should be noted, however, that other optical coupling structures known in the art can likewise be used instead of the coupler 404. This will be apparent to those skilled in the art. A primary output of the star coupler 404 is supplied to an output of the optical fiber 308, while a secondary output from the coupler 404 in this example is supplied to the optical to electrical converter (O / E) 405. It will be noted that this secondary output from the coupler 404 is optional and this embodiment of the invention of the invention can be employed without it. The output of the O / E 405 is supplied to the pump selection circuit 406 where it is used to further refine the pump selection process. Specifically, in this example O / E 405 checks the energy level of the selected signal and determines the parameters and ID tags associated with the selected line (s) that are supplied to the coupler 404. It is also supplied to the pump selection circuit 406, control and command information from the command and control unit 407 that is used with the information of other network elements in an optical system, in order to choose which of the 403 pumps are to be selected and accordingly which of the amplifiers 402 supplies an optical signal by the coupler 404 to the output optical fiber 408 as an output. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, the content of the following is claimed as property:

Claims (9)

1. CLAIMS 1. An optical selector having a plurality of feeds and an output, characterized in that it comprises: a plurality of optical amplifiers that correspond to the plurality of inputs, each used as a switching element; a coupling element for coupling optical output signals from each of the plurality of optical amplifiers; a pump structure that responds to a command signal to control the ON / OFF states of the plurality of optical amplifiers, such that one or more of the optical input signals is supplied to the output.
2. 2. The optical selector according to claim 1, characterized in that each of the optical amplifiers comprises an optical fiber adulterated with rare earth having a predetermined length and a corresponding pump that responds to the command signals to effect the ON / OFF the optical amplifier.
3. 3. The optical selector according to claim 2, characterized in that the fiber is adulterated with erbium.
4. 4. The optical selector according to claim 2, characterized in that the pump structure associated with the fiber adulterated with rare earth, is arranged to provide co-directional pumping of the optical fiber amplifier adulterated with rare earth.
5. 5. The optical selector according to claim 2, characterized in that the pump structure associated with the fiber adulterated with rare earth, is arranged to provide directional pumping of the optical fiber amplifier adulterated with rare earth.
6. 6. The optical selector according to claim 1, characterized in that each of the optical amplifiers comprises an optical fiber adulterated with rare earth having a predetermined length and a corresponding filter, the pump structure includes a tunable pump and a circuit for pump tuning, and a coupler for an output from the tunable pump to each of the filters corresponding to the plurality of optical amplifiers, the pump tuning circuit responds to command and control signals to control the synchronizable pump to supply pumping signals to effect ON / OFF one or more of the plurality of optical amplifiers, the filters separate the pump signal to effect ON / OFF of one or more of the plurality of optical amplifiers.
7. 7. The optical selector according to claim 4, characterized in that the fiber is adulterated with erbium.
8. 8. - The optical selector according to claim 6, characterized in that the pump structure associated with the fiber adulterated with rare earth, is arranged to provide co-directional pumping of the optical fiber amplifier adulterated with rare earth.
9. 9. The optical selector according to claim 6, characterized in that the pump structure associated with the fiber adulterated with rare earth is arranged to provide counter-directional pumping of the optical fiber amplifier adulterated with rare earth.