Single and multi-stage high power optical isolators using a single polarizing element

Abstract

An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

1 . An optical isolator for generally collimated laser radiation with one or more isolation stages, said optical isolator comprising:
 a single polarizing element;   at least one Faraday optical element comprising opposing optical faces through which there is a beam propagation axis;   at least one reciprocal polarization altering optical element disposed at said single polarizing element;   at least one reflective optical element for reflecting radiation to provide an even number of passes through said at least one Faraday optical element;   a magnetic structure capable of generating a magnetic field within said at least one Faraday optical element that is generally aligned with the even number of passes along said beam propagation axis; and   wherein said optical isolator is configured to receive generally collimated laser radiation, which passes through said single polarizing element and said at least one reciprocal polarization altering optical element and which makes at least two passes through said at least one Faraday optical element, whereby generally collimated laser radiation is output from said optical isolator.   
     
     
         2 . The optical isolator of  claim 1 , wherein said at least one reflective optical element comprises a reflective coating at a surface of said at least one Faraday optical element. 
     
     
         3 . The optical isolator of  claim 1 , wherein said at least one reflective optical element comprises a reflective coating at a surface of said polarization altering optical elements. 
     
     
         4 . The optical isolator of  claim 1 , wherein said at least one reflective optical element comprises a reflective coating at a surface of said single polarizing element. 
     
     
         5 . The optical isolator of  claim 1 , wherein said at least one reflective optical element comprises a mirror. 
     
     
         6 . The optical isolator of  claim 1 , wherein said at least one reciprocal polarization altering optical element comprises at least one half-wave plate. 
     
     
         7 . The optical isolator of  claim 1 , wherein said at least one reciprocal polarization altering optical element comprises at least one quarter-wave plate. 
     
     
         8 . The optical isolator of  claim 1 , wherein said at least one reciprocal polarization altering optical element comprises at least one optical rotator. 
     
     
         9 . The optical isolator of  claim 1 , wherein said single polarizing element comprises a polarizing beam displacer. 
     
     
         10 . The optical isolator of  claim 9 , wherein said polarizing beam displacer comprises a birefringent crystal. 
     
     
         11 . The optical isolator of  claim 9 , wherein said polarizing beam displacer comprises a beam displacer configured so that all backward propagating radiation is directed in the same direction as it exits the optical isolator. 
     
     
         12 . The optical isolator of  claim 1 , wherein said magnetic structure comprises an adjustable magnetic structure capable of modifying the magnetic field strength within said at least one Faraday optical element. 
     
     
         13 . The optical isolator of  claim 1 , wherein said magnetic structure comprises an adjustable magnetic structure capable of modifying the magnetic field strength within each isolation stage independently. 
     
     
         14 . The optical isolator of  claim 1 , wherein said at least one Faraday optic element comprises a layered structure with a transparent heat conductive layer bonded to one or both optical faces of a diamagnetic, paramagnetic or ferromagnetic Faraday rotating material. 
     
     
         15 . The optical isolator of  claim 1 , wherein reverse propagating radiation passes through said single polarizing element and said at least one reciprocal polarization altering optical element and makes at least two passes through said at least one Faraday optical element, whereby the reverse propagating radiation is not output from said single polarizing element in the direction of the source of the generally collimated laser radiation.