Erbium doped fibers

Abstract

A method of producing green light signals couples pump signals from at least one pump source into at least one erbium doped fiber (EDF) to cause ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, which produces green light signals. The majority of the pump signals have a wavelength at which the probability of occurrence of ESA in the EDF is greater than the probability of occurrence of GSA in the EDF. The majority of the pump signals may have a wavelength in the range approximately 920 nm to approximately 980 nm, or in the region of 960 nm. An erbium doped fiber amplifier (EDFA) for amplifying traffic-carrying signals may be pumped by green light signals produced by this method. A laser which produces green light signals may be constructed, which comprises at least one EDF, coupled to at least one pump source to receive pump signals therefrom, which cause GSA, and ESA in erbium ions of the EDF, which produces green light signals, the majority of the pump signals having a wavelength at which the probability of occurrence of ESA in the EDF is greater than the probability of occurrence of GSA in the EDF.

1 - 47 . (canceled)  
   
   
       48 . A method of producing green light signals, comprising the steps of: 
 a) coupling pump signals from at least one pump source into at least one erbium doped fiber (EDF) to cause ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, for producing the green light signals; and    b) a majority of the pump signals having a wavelength at which a probability of occurrence of ESA in the EDF is greater than a probability of occurrence of GSA in the EDF.    
   
   
       49 . The method according to  claim 48 , in which 60% of the pump signals have a wavelength at which the probability of occurrence of ESA in the EDF is greater than the probability of occurrence of GSA in the EDF.  
   
   
       50 . The method according to  claim 48 , in which the majority of the pump signals have a wavelength in a range between approximately 920 nm and approximately 980 nm.  
   
   
       51 . The method according to  claim 50 , in which the majority of the pump signals have a wavelength in a region of 960 nm.  
   
   
       52 . The method according to  claim 48 , in which the majority of the pump signals have a wavelength less than a crossover wavelength of an EDF GSA and ESA cross section peaks crossover point.  
   
   
       53 . The method according to  claim 48 , in which the at least one pump source is coupled to the EDF such that the pump signals are coupled into the EDF to propagate therealong in a first direction.  
   
   
       54 . The method according to  claim 53 , in which another pump source is coupled to the EDF such that the pump signals are coupled into the EDF to propagate therealong in a second direction, opposite to the first direction.  
   
   
       55 . The method according to  claim 48 , and reflecting at least some of the pump signals escaping from the at least one EDF back therein.  
   
   
       56 . The method according to  claim 55 , in which the reflecting step comprises placing a pump signal reflector at one of a first end and a second end of the at least one EDF.  
   
   
       57 . A device for producing green light signals, comprising: 
 a) at least one erbium doped fiber (EDF) coupled to at least one pump source to receive pump signals therefrom for causing ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, to produce the green light signals; and    b) a majority of the pump signals having a wavelength at which a probability of occurrence of ESA in the EDF is greater than a probability of occurrence of GSA in the EDF.    
   
   
       58 . A method of amplification of traffic-carrying signals in an erbium doped fiber amplifier (EDFA), comprising the steps of: 
 a) coupling pump signals from at least one pump source into at least one erbium doped fiber (EDF) to cause ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, for producing green light signals; and    b) a majority of the pump signals having a wavelength at which a probability of occurrence of ESA in the EDF is greater than a probability of occurrence of GSA in the EDF.    
   
   
       59 . The method according to  claim 58 , in which the green light signals are produced substantially externally to the EDFA, and are coupled into the EDFA.  
   
   
       60 . The method according to  claim 59 , in which the green light signals are produced using at least one device coupled to the EDFA.  
   
   
       61 . The method according to  claim 60 , in which the at least one device is coupled to one of a first end and a second end of the EDFA.  
   
   
       62 . The method according to  claim 60 , in which the EDFA comprises at least one EDF, and at least one device is coupled to the at least one EDF.  
   
   
       63 . The method according to  claim 62 , in which the at least one device is a co-directional device in which the green light signals are coupled into the EDF to propagate therealong in a same direction as the traffic-carrying signals.  
   
   
       64 . The method according to  claim 63 , in which a counter-directional device is coupled to the EDF so that the green light signals are coupled into the EDF to propagate therealong in an opposite direction to that of the traffic-carrying signals.  
   
   
       65 . The method according to  claim 63 , in which the green light signals are produced substantially within the EDFA.  
   
   
       66 . The method according to  claim 65 , in which the green light signals are produced substantially within the EDFA by pumping the EDFA with at least one pump source coupled to the EDFA, the majority of the pump signals having a wavelength at which the probability of occurrence of ESA in the EDFA is greater than the probability of occurrence of GSA in the EDFA.  
   
   
       67 . The method according to  claim 66 , in which 60% of the pump signals have a wavelength at which the probability of occurrence of ESA in the EDFA is greater than the probability of occurrence of GSA in the EDFA.  
   
   
       68 . The method according to  claim 66 , in which the majority of the pump signals have a wavelength in a range between approximately 920 nm and approximately 980 nm.  
   
   
       69 . The method according to  claim 68 , in which the majority of the pump signals have a wavelength in a region of 960 nm.  
   
   
       70 . The method according to  claim 66 , in which the at least one pump source is coupled to one of a first end and a second end of the EDFA.  
   
   
       71 . The method according to  claim 66 , in which the EDFA comprises at least one EDF, and at least one pump source coupled to the at least one EDF.  
   
   
       72 . The method according to  claim 71 , in which a co-directional pump source is coupled to the at least one EDF so that the pump signals are coupled into the at least one EDF to propagate therealong in a same direction as that of the traffic-carrying signals.  
   
   
       73 . The method according to  claim 72 , in which a counter-directional pump source is coupled to the at least one EDF so that the pump signals are coupled into the at least one EDF to propagate therealong in an opposite direction to that of the traffic-carrying signals.  
   
   
       74 . The method according to  claim 58 , and the step of reflecting at least some of the pump signals escaping from the EDFA back into the EDFA.  
   
   
       75 . The method according to  claim 74 , in which the reflecting step comprises placing a pump signal reflector at one of a first end and a second end of the EDFA.  
   
   
       76 . The method according to  claim 74 , in which the EDFA comprises at least one EDF, and the reflecting step comprises placing a pump signal reflector at one of a first end and a second end of the at least one EDF.  
   
   
       77 . The method according to  claim 75 , in which the pump signal reflector reflects the pump signals having a wavelength in a range between approximately 920 nm and approximately 980 nm.  
   
   
       78 . The method according to  claim 58 , and the step of reflecting at least some of the green light signals escaping from the EDFA back into the EDFA.  
   
   
       79 . The method according to  claim 78 , in which the reflecting step comprises placing a green light signal reflector at one of a first end and a second end of the EDFA.  
   
   
       80 . The method according to  claim 78 , in which the EDFA comprises at least one EDF, and the reflecting step comprises placing a green light signal reflector at one of a first end and a second end of the at least one EDF.  
   
   
       81 . The method according to  claim 58 , and the step of substantially preventing the green light signals from being transmitted from the EDFA.  
   
   
       82 . The method according to  claim 81 , in which the preventing step comprises placing a green light signal reflector at one of an input end and an output end of the EDFA.  
   
   
       83 . An erbium doped fiber amplifier (EDFA) for amplifying traffic-carrying signals, comprising: 
 a) at least one erbium doped fiber (EDF) coupled to at least one pump source to receive pump signals therefrom for causing ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, to produce green light signals; and    b) a majority of the pump signals having a wavelength at which a probability of occurrence of ESA in the EDF is greater than a probability of occurrence of GSA in the EDF.    
   
   
       84 . A laser for producing green light signals, comprising: 
 a) at least one erbium doped fiber (EDF) coupled to at least one pump source to receive pump signals therefrom to cause ground state absorption (GSA) and excited state absorption (ESA) in erbium ions of the EDF, for producing the green light signals; and    b) a majority of the pump signals having a wavelength at which a probability of occurrence of ESA in the EDF is greater than a probability of occurrence of GSA in the EDF.    
   
   
       85 . The laser according to  claim 84 , in which 60% of the pump signals have a wavelength at which the probability of occurrence of ESA in the EDF is greater than the probability of occurrence of GSA in the EDF.  
   
   
       86 . The laser according to  claim 84 , in which the majority of the pump signals have a wavelength in a range between approximately 920 nm and approximately 980 nm.  
   
   
       87 . The laser according to  claim 86 , in which the majority of the pump signals have a wavelength in a region of 960 nm.  
   
   
       88 . The laser according to  claim 84 , in which the at least one pump source is coupled to the EDF such that the pump signals are coupled into the EDF to propagate therealong in a first direction.  
   
   
       89 . The laser according to  claim 88 , in which the at least one pump source is coupled to the EDF such that the pump signals are coupled into the EDF to propagate therealong in a second direction, opposite to the first direction.  
   
   
       90 . The laser according to  claim 84 , and means for reflecting at least some of the pump signals escaping from the laser back into the laser.  
   
   
       91 . The laser according to  claim 90 , in which a pump signal reflector is placed at one of a first end and a second end of the laser.  
   
   
       92 . The laser according to  claim 90 , and a pump signal reflector is placed at one of a first end and a second end of the at least one EDF.  
   
   
       93 . The laser according to  claim 84 , in which a size of the laser is 50 mm×50 mm×20 mm.