Optical passive components and bi-directional amplifier

Abstract

A bi-directional polarization independent optical isolator and monitor/amplifier system simultaneously transmits two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each signal ray in its respective reverse direction. Both of the counter-propagating signal rays are amplified within an optical gain element. The separate signal rays include either two wavelength bands completely separated in wavelength or two sets of wavelengths, each of a plurality of wavelengths, such that wavelengths of the two signal rays are interspersed in alternating fashion. The bi-directional polarization independent optical isolator portion of the system comprises a birefringent polarization separation element, a reciprocal optical rotation element, a lens, a reflective element, a lens, a non-reciprocal optical rotation element, and a birefringent polarization combining element. The reflective element comprises either a mirror/waveplate assembly (which comprises a red reflector, a quarter-wave plate, and a blue reflector) or a non-linear interferometer. An assembly of four parallel optical fibers or ports is also optically coupled to the isolator such that the input and output of each pass through the isolator is coupled to a pair of diagonally disposed fibers or ports. The four fibers or ports may be configured such that either single-stage bi-directional isolation is accomplished for each of two fiber transmission lines or double stage bi-directional isolation is accomplished on a single fiber transmission line. The monitor/amplifier portion of the system is comprised of a separate assembly of four optical ports together with a second lens, two reciprocal optical rotation elements and a non-reciprocal optical rotation element. The monitor/amplifier provides for monitoring of optical power of both signal rays both before its input into and output from the optical gain element and provides for injection of two separate counter-propagating pump laser beams into the optical gain element and optical isolation of each of said pump beams from the output of the other laser.

What is claimed is:  
     
         1 . A bi-directional polarization independent optical amplifier system simultaneously transmitting two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each of the two separate signal rays in its respective reverse direction, said bi-directional polarization independent optical amplifier system comprising: 
 a bi-directional polarization independent optical isolator comprising: 
 a birefringent polarization element separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough,  
 a reciprocal optical rotation element,  
 a non-reciprocal optical rotation element, said reciprocal optical rotation element and said non-reciprocal optical rotation element together selectively rotating the direction of the plane of polarization of both of the components of each of the two separate signal rays depending upon the transmission direction of the each of the two signal rays,  
 a reflective element reflecting the components of each of the two separate signal rays and selectively rotating both of the components of one of the two separate signal rays,  
 a lens collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element, wherein said two separate signal rays are separated from each other based upon their respective wavelengths.  
   
     
     
         2 . A bi-directional polarization independent optical amplifier system simultaneously transmitting two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each of the two separate signal rays in its respective reverse direction, said bi-directional polarization independent optical amplifier system comprising: 
 a bi-directional polarization independent optical isolator comprising: 
 a birefringent polarization element separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough,  
 a reciprocal optical rotation element,  
 a non-reciprocal optical rotation element, said reciprocal optical rotation element and said non-reciprocal optical rotation element together selectively rotating the direction of the plane of polarization of both of the components of each of the two separate signal rays depending upon the transmission direction of the each of the two signal rays,  
 a reflective element reflecting the components of each of the two separate signal rays and selectively rotating both of the components of one of the two separate signal rays and comprising a mirror/waveplate assembly,  
 a lens collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element, wherein said two separate signal rays are separated into two, respective and separate wavelength bands.  
   
     
     
         3 . The bi-directional polarization independent optical amplifier system as recited in  claim 2 , further comprising an assembly of four parallel optical ports optically coupled to the bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the isolator is coupled to a pair of diagonally disposed ports, said four ports being configured such that either single-stage bi-directional isolation is accomplished for each of two optical transmission lines or double stage bi-directional isolation is accomplished on a single optical transmission line.  
     
     
         4 . The bi-directional polarization independent optical amplifier system as recited in  claim 3 , further comprising a monitor/amplifier assembly monitoring a first portion of the components of each of the two separate signal rays traveling in its respective forward direction and amplifying another portion of the components of each of the two separate signal rays traveling in its respective forward direction, said monitor/amplifier assembly comprising: 
 an input monitor monitoring each first portion of the components, 
 a laser pump amplifying each another portion of the components by injecting a laser pump beam into the optical path of the another portion of the components of the two separate signal rays traveling in the forward direction, and  
 a second lens focusing the components onto the monitor and collimating and directing the laser pump beam onto the reflective element.  
   
     
     
         5 . The bi-directional polarization independent optical amplifier system as recited in  claim 4 , wherein the monitor/amplifier assembly further comprises: 
 a monitor/amplifier birefringent polarization element separating a pump laser beam traveling therethrough into components thereof and selectively re-combining the first portion of the components of the each of the two separate signal rays into two respective monitor signal rays upon a traverse therethrough;    a first monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough;    a second monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough; and    a monitor/amplifier non-reciprocal rotating optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough, wherein the monitor/amplifier birefringent polarization element, the first monitor/amplifier reciprocal optical rotation element, the second monitor/amplifier reciprocal optical rotation element, and the monitor/amplifier non-reciprocal optical rotation element are configured such that the components of each of the two separate signal rays traveling in its respective forward direction are monitored and amplified.    
     
     
         6 . The bi-directional polarization independent optical amplifier system as recited in  claim 5 , wherein the monitor/amplifier assembly further comprises an assembly of four parallel optical ports optically coupled to the monitor/amplifier birefringent polarization element and receiving the portion of the components and transmitting the laser pump beam.  
     
     
         7 . The bi-directional polarization independent optical amplifier system as recited in  claim 3 , wherein a first of the four parallel optical ports is optically coupled to a second of the four parallel optical ports such that an output of a first pass of the two separate signal rays traveling in a forward direction through the bi-directional polarization independent optical isolator is returned to the bi-directional polarization independent optical isolator and an output of a second pass through the bi-directional polarization independent optical isolator is output from the bi-directional polarization independent optical amplifier system.  
     
     
         8 . The bi-directional polarization independent optical amplifier system as recited in  claim 7 , further comprising an optical gain element optically coupled to a third of the four parallel optical ports, wherein the output of a first pass from the bi-directional polarization independent optical amplifier system is amplified by the optical gain element wherein the pump laser beam propagates together with said output within the optical gain element.  
     
     
         9 . The bi-directional polarization independent optical amplifier system as recited in  claim 7 , further comprising an optical gain element optically coupled to a third of the four parallel optical ports, wherein the output of a second pass from the bi-directional polarization independent optical amplifier system is amplified by the optical gain element wherein the pump laser beam propagates together with said output within the optical gain element.  
     
     
         10 . A bi-directional polarization independent optical amplifier system simultaneously transmitting two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each of the two separate signal rays in its respective reverse direction, said bi-directional polarization independent optical amplifier system comprising: 
 a bi-directional polarization independent optical isolator comprising: 
 a birefringent polarization element separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough,  
 a reciprocal optical rotation element,  
 a non-reciprocal optical rotation element, said reciprocal optical rotation element and said non-reciprocal optical rotation element together selectively rotating the direction of the plane of polarization of both of the components of each of the two separate signal rays depending upon the transmission direction of the each of the two signal rays,  
 a reflective element reflecting the components of each of the two separate signal rays and selectively rotating both of the components of one of the two separate signal rays and comprising a non-linear interferometer,  
 a lens collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element, wherein said two separate signal rays include two sets of wavelengths, each of the two sets of wavelengths including a plurality of wavelengths, such that wavelengths of the two signal rays are alternatingly interspersed with each other.  
   
     
     
         11 . The bi-directional polarization independent optical amplifier system as recited in  claim 10 , further comprising an assembly of four parallel optical ports optically coupled to the bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the isolator is coupled to a pair of diagonally disposed ports, said four ports being configured such that either single-stage bi-directional isolation is accomplished for each of two optical transmission lines or double stage bi-directional isolation is accomplished on a single optical transmission line.  
     
     
         12 . The bi-directional polarization independent optical amplifier system as recited in  claim 11 , further comprising a monitor/amplifier assembly monitoring a first portion of the components of each of the two separate signal rays traveling in its respective forward direction and amplifying another portion of the components of each of the two separate signal rays traveling in the forward direction, said monitor/amplifier assembly comprising: 
 an input monitor monitoring each first portion of the components,    a laser pump amplifying each another portion of the components by injecting a laser pump beam into the optical path of the another portion of the components of the two separate signal rays traveling in the forward direction, and    a second lens focusing the components onto the monitor and collimating and directing the laser pump beam onto the reflective element.    
     
     
         13 . The bi-directional polarization independent optical amplifier system as recited in  claim 12 , wherein the monitor/amplifier assembly further comprises: 
 a monitor/amplifier birefringent polarization element separating a pump laser beam traveling therethrough into components thereof and selectively re-combining the first portion of the components of the each of the two separate signal rays into two respective monitor signal rays upon a traverse therethrough;    a first monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough;    a second monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough; and    a monitor/amplifier non-reciprocal rotating optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough, wherein the monitor/amplifier birefringent polarization element, the first monitor/amplifier reciprocal optical rotation element, the second monitor/amplifier reciprocal optical rotation element, and the monitor/amplifier non-reciprocal optical rotation element are configured such that the components of each of the two separate signal rays traveling in its respective forward direction are monitored and amplified.    
     
     
         14 . The bi-directional polarization independent optical amplifier system as recited in  claim 13 , wherein the monitor/amplifier assembly further comprises an assembly of four parallel optical ports optically coupled to the monitor/amplifier birefringent polarization element and receiving the portion of the components and transmitting the laser pump beam.  
     
     
         15 . The bi-directional polarization independent optical amplifier system as recited in  claim 11 , wherein a first of the four parallel optical ports is optically coupled to a second of the four parallel optical ports such that an output of a first pass of the two separate signal rays traveling in a forward direction through the bi-directional polarization independent optical isolator is returned to the bi-directional polarization independent optical isolator and an output of a second pass through the bi-directional polarization independent optical isolator is output from the bi-directional polarization independent optical amplifier system.  
     
     
         16 . The bi-directional polarization independent optical amplifier system as recited in  claim 15 , further comprising an optical gain element optically coupled to a third of the four parallel optical ports, wherein the output of a first pass from the bi-directional polarization independent optical amplifier system is amplified by the optical gain element wherein the pump laser beam propagates together with said output within the optical gain element.  
     
     
         17 . The bi-directional polarization independent optical amplifier system as recited in  claim 15 , further comprising an optical gain element optically coupled to a third of the four parallel optical ports, wherein the output of a second pass from the bi-directional polarization independent optical amplifier system is amplified by the optical gain element wherein the pump laser beam propagates together with said output within the optical gain element.  
     
     
         18 . A bi-directional polarization independent optical amplifier system simultaneously transmitting two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each signal ray in its respective reverse direction, said bi-directional polarization independent optical amplifier system comprising: 
 means for separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough;    first means for selectively rotating the direction of the plane of polarization of the components of each of the two separate signal rays;    means for reflecting the components of each of the two separate signal rays and selectively rotating the polarization plane of one of the two separate signal rays; and    means for collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element; wherein said two separate signal rays are separated from each other based upon their respective wavelengths.    
     
     
         19 . The bi-directional polarization independent optical amplifier system as recited in  claim 18 , wherein said two separate signal rays are separated into two, respective and separate wavelength bands.  
     
     
         20 . The bi-directional polarization independent optical amplifier system as recited in  claim 18 , wherein said two separate signal rays include two sets of wavelengths, each of a plurality of wavelengths, such that wavelengths of the two signal rays are alternatingly interspersed with each other.  
     
     
         21 . A method of bi-directional optical amplification of signal rays within an optical communications system, said method comprising: 
 simultaneously inputting into each of a first and a second bi-directional polarization independent optical isolator and monitor/amplifier system one of two separate signal rays from a first span and a second span, respectively, of the optical communications system, each of said first and second bi-directional polarization independent optical isolator and monitor/amplifier systems causing simultaneous transmission of the two separate signal rays in opposite forward directions through an optical gain element while simultaneously suppressing backward transmission of each of the two separate signal rays in its respective reverse direction.    
     
     
         22 . The method as recited in  claim 21 , further comprising: 
 transmitting by the first bi-directional polarization independent optical isolator and monitor/amplifier system a first pump laser beam through the optical gain element and transmitting by the second bi-directional polarization independent optical isolator and monitor/amplifier system a second pump laser beam through the optical gain element together with the two separate signal rays.    
     
     
         23 . The method as recited in  claim 22 , further comprising: 
 simultaneously outputting the two separate signal rays from opposite first and second ends of the optical gain element into the first and second, respectively, bi-directional polarization independent optical isolator and monitor/amplifier system, wherein both signal rays are simultaneously amplified within the optical gain element, and wherein an output end of the first of the two signal rays is an input end of the second of the two signal rays and an output end of the second of the two signal rays is an input end of the first of the two signal rays.    
     
     
         24 . The method as recited in  claim 21 , further comprising the step of: 
 monitoring, by each of the first and second bi-directional polarization independent optical isolator and monitor/amplifier systems, optical power of one of the two signal rays before its input into the optical gain element and optical power of another of the two signal rays after its output from the optical gain element.    
     
     
         25 . The method as recited in  claim 22 , wherein the first pump laser beam is transmitted by the first bi-directional polarization independent optical isolator and monitor/amplifier system through the optical gain element in a same direction as a first of the two signal rays and another pump laser beam is transmitted by the second bi-directional polarization independent optical isolator and monitor/amplifier system through the optical gain element in a same direction as a second of the two signal rays and wherein each of said pump laser beams is prevented by the bi-directional polarization independent optical isolator and monitor/amplifier systems from being output at the input of the other of the pump laser beams.  
     
     
         26 . The method as recited in  claim 21 , wherein said two separate signal rays are separated into two, respective and separate wavelength bands.  
     
     
         27 . The method as recited in  claim 21 , wherein said two separate signal rays include two sets of wavelengths, each including a plurality of wavelengths, such that wavelengths of the two signal rays are alternatingly interspersed with each other.  
     
     
         28 . A method of asymmetric interleaved bi-directional wavelength multiplexed optical signal propagation in a light wave communications system, comprising: 
 propagating through a bi-directional polarization independent optical isolator a first set of channels included within a first set of bands in a first direction and a second set of channels included within a second set of bands in a second direction opposite to the first direction, wherein the first and second bands are interleaved with one another.    
     
     
         29 . The method as recited in  claim 28 , wherein the width of bands of the first set of bands is not equal to the width of bands of the second set of bands.  
     
     
         30 . The method as recited in  claim 28 , wherein the width of bands of the first set of bands is equal to the width of bands of the second set of bands.  
     
     
         31 . A bi-directional fiber amplifier system for two light signals propagating in opposite directions in a single fiber optic line, comprising: 
 an optical gain element propagating therethrough the two light signals;    bi-directional polarization independent optical isolators coupled to the optical gain element and simultaneously inputting the two separate light signals from opposite ends of the optical gain element, said bi-directional polarization independent optical isolators causing simultaneous transmission of the two separate light signals in opposite forward directions while simultaneously suppressing backward transmission of each of the two separate light signals in its respective reverse direction; and    pump lasers, respectively coupled to each of the bi-directional polarization independent optical isolators, and amplifying the two separate light signals in the optical gain element.    
     
     
         32 . The bi-directional fiber amplifier system as recited in  claim 31 , further comprising photo-detectors measuring a power of the two separate light signals.  
     
     
         33 . The bi-directional fiber amplifier system as recited in  claim 32 , further comprising a comparison and control logic system monitoring the photo-detectors and controlling outputs of the pump lasers accordingly.  
     
     
         34 . A bi-directional polarization independent optical amplifier system simultaneously transmitting two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each of the two separate signal rays in its respective reverse direction, said bi-directional polarization independent optical amplifier system comprising: 
 an optical gain element comprising two ends;    a first bi-directional polarization independent optical isolator optically coupled to a first end of the optical gain element; and    a second bi-directional polarization independent optical isolator optically coupled to a second end of the optical gain element, wherein said two separate signal rays are separated from each other based upon their respective wavelengths.    
     
     
         35 . The bi-directional polarization independent optical amplifier system as recited in  claim 34 , wherein each of the first bi-directional polarization independent optical isolator and the second bi-directional polarization independent optical isolator comprises: 
 a birefringent polarization element separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough,    a reciprocal optical rotation element,    a non-reciprocal optical rotation element, said reciprocal optical rotation element and said non-reciprocal optical rotation element together selectively rotating the direction of the plane of polarization of both of the components of each of the two separate signal rays depending upon the transmission direction of the each of the two signal rays,    a reflective element reflecting the components of each of the two separate signal rays and selectively rotating both of the components of one of the two separate signal rays and comprising a mirror/waveplate assembly,    a lens collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element, wherein said two separate signal rays are separated into two, respective and separate wavelength bands.    
     
     
         36 . The bi-directional polarization independent optical amplifier system as recited in  claim 35 , further comprising: 
 a first assembly of four parallel optical ports optically coupled to the first bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the first isolator is coupled to a pair of diagonally disposed ports, and    a second assembly of four parallel optical ports optically coupled to the second bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the second isolator is coupled to a pair of diagonally disposed ports.    
     
     
         37 . The bi-directional polarization independent optical amplifier system as recited in  claim 36 , further comprising: 
 a first monitor/amplifier assembly optically coupled to the first bi-directional polarization independent optical isolator, and    a second monitor/amplifier assembly optically coupled to the second bi-directional polarization independent optical isolator, wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly monitors a first portion of the components of each of the two separate signal rays traveling in its respective forward direction and amplifies another portion of the components of each of the two separate signal rays traveling in its respective forward direction.    
     
     
         38 . The bi-directional polarization independent optical amplifier system as recited in  claim 37 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly comprises: 
 an input monitor monitoring each first portion of the components,    a laser pump amplifying each another portion of the components by injecting a laser pump beam into the optical path of the another portion of the components of the two separate signal rays traveling in the forward direction, and    a monitor/amplifier lens focusing the components onto the monitor and collimating and directing the laser pump beam onto the reflective element.    
     
     
         39 . The bi-directional polarization independent optical amplifier system as recited in  claim 38 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly further comprises: 
 a monitor/amplifier birefringent polarization element separating a pump laser beam traveling therethrough into components thereof and selectively re-combining the first portion of the components of the each of the two separate signal rays into two respective monitor signal rays upon a traverse therethrough;    a first monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough;    a second monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough; and    a monitor/amplifier non-reciprocal rotating optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough, wherein the birefringent polarization element, the reciprocal optical rotation element, the non-reciprocal optical rotation element, the lens, the monitor/amplifier lens, the monitor/amplifier birefringent polarization element, the first monitor/amplifier reciprocal optical rotation element, the second monitor/amplifier reciprocal optical rotation element, and the monitor/amplifier non-reciprocal optical rotation element are configured such that the components of each of the two separate signal rays traveling in its respective forward direction are monitored and amplified.    
     
     
         40 . The bi-directional polarization independent optical amplifier system as recited in  claim 39 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly further comprises an assembly of four parallel optical ports optically coupled to the monitor/amplifier birefringent polarization element and receiving the portion of the components and transmitting the laser pump beam.  
     
     
         41 . The bi-directional polarization independent optical amplifier system as recited in  claim 36 , wherein the first end of the optical gain element is optically coupled to a first port of the first assembly of four parallel optical ports and the second end of the optical gain element is optically coupled to a first port of the second assembly of four parallel optical ports and a second port and a third port of the first assembly of four parallel optical ports are optically coupled to one another and a second port and a third port of the second assembly of four parallel optical ports are optically coupled to one another such that an output of a second pass of a first signal ray of the two signal rays through the first bi-directional polarization independent optical isolator is output from the first bi-directional polarization independent optical isolator to said optical gain element and an output of a second pass of a second signal ray of the two signal rays through the second bi-directional polarization independent optical isolator is output from the second bi-directional polarization independent optical isolator to said optical gain element.  
     
     
         42 . The bi-directional polarization independent optical amplifier system as recited in  claim 41 , wherein the output of a second pass of the first signal ray from the first bi-directional polarization independent optical isolator is amplified by the optical gain element wherein a first pump laser beam propagates together with said first signal ray output along its forward direction within the optical gain element and the output of a second pass of the second signal ray from the second bi-directional polarization independent optical isolator is amplified by the optical gain element wherein a second pump laser beam propagates together with said second signal ray output along its forward direction within the optical gain element.  
     
     
         43 . The bi-directional polarization independent optical amplifier as recited in  claim 34 , wherein each of the first bi-directional polarization independent optical isolator and the second bi-directional polarization independent optical isolator comprises: 
 a birefringent polarization element separating each of the two separate signal rays into components thereof upon a first traverse therethrough and selectively re-combining the components of the two separate signal rays into two respective output signal rays upon a second traverse therethrough,    a reciprocal optical rotation element,    a non-reciprocal optical rotation element, said reciprocal optical rotation element and said non-reciprocal optical rotation element together selectively rotating the direction of the plane of polarization of both of the components of each of the two separate signal rays depending upon the transmission direction of the each of the two signal rays,    a reflective element reflecting the components of each of the two separate signal rays and selectively rotating both of the components of one of the two separate signal rays and comprising a non-linear interferometer,    a lens collimating and directing the components of the two separate signal rays traveling in a forward direction onto the reflective element, and focusing the reflected components onto the birefringent polarization element, wherein said two separate signal rays include two sets of wavelengths, each of the two sets of wavelengths including a plurality of wavelengths, such that wavelengths of the two signal rays are alternatingly interspersed with each other.    
     
     
         44 . The bi-directional polarization independent optical amplifier system as recited in  claim 43 , further comprising: 
 a first assembly of four parallel optical ports optically coupled to the first bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the first isolator is coupled to a pair of diagonally disposed ports, and    a second assembly of four parallel optical ports optically coupled to the second bi-directional polarization independent optical isolator such that corresponding input and output of each pass of the two separate signal rays through the second isolator is coupled to a pair of diagonally disposed ports.    
     
     
         45 . The bi-directional polarization independent optical amplifier system as recited in  claim 44 , further comprising: 
 a first monitor/amplifier assembly optically coupled to the first bi-directional polarization independent optical isolator, and    a second monitor/amplifier assembly optically coupled to the second bi-directional polarization independent optical isolator, wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly monitors a first portion of the components of each of the two separate signal rays traveling in its respective forward direction and amplifies another portion of the components of each of the two separate signal rays traveling in its respective forward direction.    
     
     
         46 . The bi-directional polarization independent optical amplifier system as recited in  claim 45 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly comprises: 
 an input monitor monitoring each first portion of the components,    a laser pump amplifying each another portion of the components by injecting a laser pump beam into the optical path of the another portion of the components of the two separate signal rays traveling in the forward direction, and    a monitor/amplifier lens focusing the components onto the monitor and collimating and directing the laser pump beam onto the reflective element.    
     
     
         47 . The bi-directional polarization independent optical amplifier system as recited in  claim 46 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly further comprises: 
 a monitor/amplifier birefringent polarization element separating a pump laser beam traveling therethrough into components thereof and selectively re-combining the first portion of the components of the each of the two separate signal rays into two respective monitor signal rays upon a traverse therethrough;    a first monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough;    a second monitor/amplifier reciprocal optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough; and    a monitor/amplifier non-reciprocal rotating optical rotation element selectively rotating the direction of the plane of polarization of light rays passing therethrough, wherein the birefringent polarization element, the reciprocal optical rotation element, the non-reciprocal optical rotation element, the lens, the monitor/amplifier lens, the monitor/amplifier birefringent polarization element, the first monitor/amplifier reciprocal optical rotation element, the second monitor/amplifier reciprocal optical rotation element, and the monitor/amplifier non-reciprocal optical rotation element are configured such that the components of each of the two separate signal rays traveling in its respective forward direction are monitored and amplified.    
     
     
         48 . The bi-directional polarization independent optical amplifier system as recited in  claim 47 , wherein each of the first monitor/amplifier assembly and the second monitor/amplifier assembly further comprises an assembly of four parallel optical ports optically coupled to the monitor/amplifier birefringent polarization element and receiving the portion of the components and transmitting the laser pump beam.  
     
     
         49 . The bi-directional polarization independent optical amplifier system as recited in  claim 44 , wherein the first end of the optical gain element is optically coupled to a first port of the first assembly of four parallel optical ports and the second end of the optical gain element is optically coupled to a first port of the second assembly of four-parallel optical ports and a second port and a third port of the first assembly of four parallel optical ports are optically coupled to one another and a second port and a third port of the second assembly of four parallel optical ports are optically coupled to one another such that an output of a second pass of a first signal ray of the two signal rays through the first bi-directional polarization independent optical isolator is output from the first bi-directional polarization independent optical isolator to said optical gain element and an output of a second pass of a second signal ray of the two signal rays through the second bi-directional polarization independent optical isolator is output from the second bi-directional polarization independent optical isolator to said optical gain element.  
     
     
         50 . The bi-directional polarization independent optical amplifier system as recited in  claim 49 , wherein the output of a second pass of the first signal ray from the first bi-directional polarization independent optical isolator is amplified by the optical gain element wherein a first pump laser beam propagates together with said first signal ray output along its forward direction within the optical gain element and the output of a second pass of the second signal ray from the second bi-directional polarization independent optical isolator is amplified by the optical gain element wherein a second pump laser beam propagates together with said second signal ray output along its forward direction within the optical gain element.