Wavelength selective switch with reduced chromatic dispersion and polarization-dependent loss

Abstract

A reduced polarization-dependent loss optical device utilizing two or more dispersive elements or a single dispersive element and a turning mirror, wherein the optical signal makes two passes through said single dispersive element when reflected from said turning mirror, and wherein the two or more dispersive elements or double pass single dispersive element has lower dispersion compared to a functionally equivalent single dispersive element, resulting in lower polarization dependent loss, reduced chromatic dispersion and increased wavelength dispersion. Moreover, a wavelength selective switch incorporating the optical device utilizing aperture-shared optics and functionally distinct planes of operation that enables high fiber port counts, such as 1×41, and multiplicative expansion, such as to 1×83 or 1×145, by utilizing elements optimized for performance in one of the functionally distinct planes of operation without affecting the other plane.

1 . A reduced polarization-dependent loss optical system comprising two or more dispersive elements and a turning mirror. 
   
   
       2 . The optical system of  claim 1 , wherein said dispersive elements lie in series with the optical signal. 
   
   
       3 . The optical system of  claim 1 , wherein said dispersive elements are transmissive. 
   
   
       4 . The optical system of  claim 1 , wherein said dispersive elements are positioned adjacent to one another, at an angle such that the optical signal from one dispersive element of said two dispersive elements is directed toward the other dispersive element of said two dispersive elements. 
   
   
       5 . The optical system of  claim 1 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, photonic crystals and combinations thereof. 
   
   
       6 . A method of reducing polarization dependent loss and chromatic dispersion in a wavelength selective switch, said method comprising the step of:
 incorporating two or more dispersive elements and a turning mirror into said switch.   
   
   
       7 . The method of  claim 6 , wherein said two or more dispersive elements have lower dispersion than a functionally equivalent single dispersive element. 
   
   
       8 . The method of  claim 6 , wherein said two or more dispersive elements increase an optical signal wavelength dispersion. 
   
   
       9 . A reduced polarization-dependent loss optical system comprising two or more dispersive elements, wherein each of said two or more dispersive elements has lower dispersion than a functionally equivalent single dispersive element. 
   
   
       10 . The optical system of  claim 9 , wherein said dispersive elements lie in series with an optical signal. 
   
   
       11 . The optical system of  claim 9 , wherein said dispersive elements are reflective. 
   
   
       12 . The optical system of  claim 9 , wherein said dispersive elements are transmissive. 
   
   
       13 . The optical system of  claim 9 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, photonic crystals and combinations thereof. 
   
   
       14 . A method of reducing polarization dependent loss and chromatic dispersion in a wavelength selective switch, said method comprising the step of:
 incorporating two or more dispersive elements into said switch.   
   
   
       15 . The method of  claim 14 , wherein said two or more dispersive elements have lower dispersion than a functionally equivalent single dispersive element. 
   
   
       16 . The method of  claim 14 , wherein said two or more dispersive elements increase an optical signal's wavelength dispersion. 
   
   
       17 . The method of  claim 14 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, photonic crystals and combinations thereof. 
   
   
       18 . A reduced polarization-dependent loss optical system comprising a single dispersive element and a turning mirror, wherein an optical signal passes through said single dispersive element, is reflected from said turning mirror, and passes a second time through said single dispersive element. 
   
   
       19 . The optical system of  claim 18 , wherein said passes of said optical signal through said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       20 . The optical system of  claim 18 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       21 . The optical system of  claim 18 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       22 . A method of reducing polarization dependent loss and chromatic dispersion in a wavelength selective switch, said method comprising the step of:
 incorporating a single dispersive element and a turning mirror into said switch, wherein an optical signal passes through said single dispersive element, is reflected from said turning mirror, and passes a second time through said single dispersive element.   
   
   
       23 . The method of  claim 22 , wherein said single dispersive element has lower dispersion than a functionally equivalent single pass dispersive element. 
   
   
       24 . The method of  claim 22 , wherein said dispersive element and said turning mirror increase wavelength dispersion. 
   
   
       25 . The method of  claim 22 , further comprising the step of:
 incorporating a quarter waveplate into said switch.   
   
   
       26 . The method of  claim 22 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       27 . A reduced polarization-dependent loss optical device comprising a single dispersive element and a turning mirror, wherein an optical signal reflects from said single dispersive element, is reflected from said turning mirror, and reflects a second time from said single dispersive element. 
   
   
       28 . The optical device of  claim 27 , wherein said reflections of said optical signal over said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       29 . The optical system of  claim 27 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       30 . The optical system of  claim 27 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       31 . The optical device of  claim 27 , wherein said reflections of said optical signal over said single dispersive element occur at different positions on said single dispersive element. 
   
   
       32 . A method of reducing polarization dependent loss and chromatic dispersion in a wavelength selective switch, said method comprising the step of:
 incorporating a single dispersive element and a turning mirror into said switch, wherein an optical signal reflects from said single dispersive element, is reflected from said turning mirror, and reflects a second time from said single dispersive element.   
   
   
       33 . The method of  claim 32 , wherein said single dispersive element has lower dispersion than a functionally equivalent single pass dispersive element. 
   
   
       34 . The method of  claim 32 , wherein said dispersive element and said turning mirror increase wavelength dispersion. 
   
   
       35 . The method of  claim 32 , further comprising the step of:
 incorporating a quarter waveplate into said switch.   
   
   
       36 . The method of  claim 32 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       37 . A reduced polarization-dependent loss optical device comprising:
 a beam splitter; and   two or more dispersive elements, wherein said two or more dispersive elements each receive a portion of a circularly-polarized optical signal from said beam splitter.   
   
   
       38 . The optical device of  claim 37 , wherein said dispersive elements lie in series with said portions of said circularly-polarized optical signal. 
   
   
       39 . The optical system of  claim 37 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, photonic crystals and combinations thereof. 
   
   
       40 . The optical device of  claim 37 , wherein said dispersive elements are reflective. 
   
   
       41 . A method of reducing polarization dependent loss and chromatic dispersion in a wavelength selective optical switch, said method comprising the step of:
 incorporating a beam splitter and two or more dispersive elements into said switch, wherein said two or more dispersive elements each receive a portion of a circularly-polarized optical signal from said beam splitter.   
   
   
       42 . The method of  claim 41 , wherein said two or more dispersive elements have lower dispersion than a functionally equivalent single dispersive element. 
   
   
       43 . The method of  claim 41 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       44 . A wavelength selective switch for switching wavelengths from one or more optical signals, each signal comprising one or more optical wavelengths, each constituting a work piece, the wavelength selective switch comprising:
 a plurality of fiber ports arranged in a fiber port array;   a plurality of optical elements operable with said plurality of fiber ports;   two or more dispersive elements operable with said plurality of fiber ports to separate at least one optical signal into a plurality of wavelength components, wherein said two or more dispersive elements each have lower dispersion than a functionally equivalent single dispersive element; and   a switching element operable with said plurality of wavelength components and controllable to guide a selected one of said plurality of wavelength components to a selected one of said plurality of fiber ports.   
   
   
       45 . The wavelength selective switch of  claim 44 , wherein said dispersive elements lie in series with the optical signal. 
   
   
       46 . The wavelength selective switch of  claim 44 , wherein said dispersive elements are reflective. 
   
   
       47 . The wavelength selective switch of  claim 44 , wherein said dispersive elements are transmissive. 
   
   
       48 . The wavelength selective switch of  claim 44 , further comprising a beam splitter and wherein said two or more dispersive elements each receive a portion of a circularly-polarized optical signal from said beam splitter. 
   
   
       49 . The wavelength selective switch of  claim 48 , wherein said dispersive elements lie in series with said circularly-polarized optical signal. 
   
   
       50 . The wavelength selective switch of  claim 44 , further comprising a turning mirror. 
   
   
       51 . The optical system of  claim 44 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, photonic crystals and combinations thereof. 
   
   
       52 . The wavelength selective switch of  claim 44 , wherein said dispersive elements are positioned adjacent to one another, at an angle such that the optical signal from one dispersive element of said two dispersive elements is directed toward the other dispersive element of said two dispersive elements. 
   
   
       53 . A wavelength selective switch for switching wavelengths from one or more optical signals, the signal comprising one or more optical wavelengths, each constituting a work piece, the wavelength selective switch comprising:
 a plurality of fiber ports arranged in a fiber port array;   a plurality of optical elements operable with said plurality of fiber ports;   a turning mirror;   a single dispersive element operable with said plurality of fiber ports to separate at least one optical signal into a plurality of wavelength components, wherein an optical signal passes through said single dispersive element, is reflected from said turning mirror, and passes a second time through said single dispersive element; and   a switching element operable with the plurality of wavelength components and controllable to guide a selected one of the plurality of wavelength components to a selected one of said plurality of fiber ports.   
   
   
       54 . The wavelength selective switch of  claim 53 , wherein said dispersive element is transmissive. 
   
   
       55 . The wavelength selective switch of  claim 54 , wherein said passes of said optical signal through said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       56 . The optical system of  claim 54 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       57 . The optical system of  claim 54 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       58 . The optical system of  claim 54 , wherein said single dispersive element has lower dispersion than a functionally equivalent single pass dispersive element. 
   
   
       59 . The wavelength selective switch of  claim 53 , wherein said dispersive element is reflective. 
   
   
       60 . The wavelength selective switch of  claim 59 , wherein said optical signal makes two passes over said single dispersive element when reflected from said turning mirror. 
   
   
       61 . The wavelength selective switch of  claim 60 , wherein said two passes of said optical signal over said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       62 . The wavelength selective switch of  claim 60 , wherein said two passes of the optical signal over said single dispersive element occur in different positions on said single dispersive element. 
   
   
       63 . The wavelength selective switch of  claim 59 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       64 . The wavelength selective switch of  claim 59 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       65 . The wavelength selective switch of  claim 59 , wherein said dispersive element has lower dispersion than a functionally equivalent single pass dispersive element. 
   
   
       66 . A wavelength selective switch for switching wavelengths from one or more optical signals, the signal comprising one or more optical wavelengths, each constituting a work piece, the wavelength selective switch comprising:
 a plurality of fiber ports arranged in a fiber port array;   a plurality of optical elements operable with said plurality of fiber ports;   two or more dispersive elements operable with said plurality of fiber ports to separate at least one optical signal into a plurality of wavelength components, wherein each of said two or more dispersive elements has lower dispersion than a functionally equivalent single dispersive element;   a switching element operable with said plurality of wavelength components and controllable to guide a selected one of said plurality of wavelength components to a selected one of said plurality of fiber ports, and   a beam steering element operable to converge a common wavelength from said plurality of fiber ports on to a specific wavelength-associated switching element;   wherein at least one of said plurality of optical elements, said dispersive element, and said switching element affects an optical property of at least one optical signal in a first plane, and wherein said at least one of said plurality of optical elements, said dispersive element, and said switching element does not substantially affect said optical property in a second plane, said first plane being generally orthogonal to said second plane.   
   
   
       67 . The wavelength selective switch of  claim 66 , wherein said dispersive elements are reflective. 
   
   
       68 . The wavelength selective switch of  claim 67 , wherein said dispersive elements lie in series with an optical signal. 
   
   
       69 . The wavelength selective switch of  claim 67 , further comprising a beam splitter and wherein said two or more dispersive elements each receive a portion of a circularly-polarized optical signal from said beam splitter. 
   
   
       70 . The wavelength selective switch of  claim 67 , wherein said dispersive elements lie in series with said portions of said circularly-polarized optical signal. 
   
   
       71 . The wavelength selective switch of  claim 67 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       72 . The wavelength selective switch of  claim 67 , further comprising a turning mirror. 
   
   
       73 . The wavelength selective switch of  claim 67 , wherein said two or more dispersive elements have lower dispersion than a functionally equivalent single dispersive element. 
   
   
       74 . The wavelength selective switch of  claim 66 , wherein said dispersive elements are transmissive. 
   
   
       75 . The wavelength selective switch of  claim 74 , wherein said dispersive elements lie in series with an optical signal. 
   
   
       76 . The wavelength selective switch of  claim 74 , wherein said dispersive elements are positioned adjacent to one another, at an angle such that said optical signal from one dispersive element of said two dispersive elements is directed toward the other dispersive element of said two dispersive elements. 
   
   
       77 . The wavelength selective switch of  claim 74 , wherein said two or more dispersive elements are selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       78 . The wavelength selective switch of  claim 74 , further comprising a turning mirror. 
   
   
       79 . The wavelength selective switch of  claim 74 , wherein said two or more dispersive elements have lower dispersion than a functionally equivalent single dispersive element. 
   
   
       80 . A wavelength selective switch for switching wavelengths from one or more optical signals, the signal comprising one or more optical wavelengths, each constituting a work piece, the wavelength selective switch comprising:
 a plurality of fiber ports arranged in a fiber port array;   a plurality of optical elements operable with said plurality of fiber ports;   a turning mirror;   a single dispersive element operable with said plurality of fiber ports to separate at least one optical signal into a plurality of wavelength components, wherein an optical signal passes through said single dispersive element, is reflected from said turning mirror, and passes a second time through said single dispersive element; and   a switching element operable with the plurality of wavelength components and controllable to guide a selected one of the plurality of wavelength components to a selected one of said plurality of fiber ports, and   a beam steering element operable to converge a common wavelength from said plurality of fiber ports on to a specific wavelength-associated switching element;   wherein at least one of said plurality of optical elements, said dispersive element, and said switching element affects an optical property of at least one optical signal in a first plane, and wherein said at least one of said plurality of optical elements, said dispersive element, and said switching element does not substantially affect said optical property in a second plane, said first plane being generally orthogonal to said second plane.   
   
   
       81 . The wavelength selective switch of  claim 80 , wherein said dispersive element is transmissive. 
   
   
       82 . The wavelength selective switch of  claim 81 , wherein said passes of said optical signal through said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       83 . The wavelength selective switch of  claim 81 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       84 . The wavelength selective switch of  claim 81 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       85 . The wavelength selective switch of  claim 81 , wherein said single dispersive element has lower dispersion than a functionally equivalent single pass dispersive element. 
   
   
       86 . The wavelength selective switch of  claim 80 , wherein said single dispersive element is reflective. 
   
   
       87 . The wavelength selective switch of  claim 80 , wherein said optical signal makes two passes over said single dispersive element when reflected from said turning mirror. 
   
   
       88 . The wavelength selective switch of  claim 87 , wherein said two passes of said optical signal over said single dispersive element occur in substantially the same position on said single dispersive element. 
   
   
       89 . The wavelength selective switch of  claim 87 , wherein said passes of said optical signal over said single dispersive element occur in different positions on said single dispersive element. 
   
   
       90 . The wavelength selective switch of  claim 86 , further comprising a quarter waveplate positioned approximate said turning mirror. 
   
   
       91 . The wavelength selective switch of  claim 86 , wherein said single dispersive element is selected from a group consisting of optical prisms, gratings, diffractive elements, holographic elements, liquid crystals, liquid crystals on silicon, and photonic crystals. 
   
   
       92 . The wavelength selective switch of  claim 86 , wherein said dispersive element has lower dispersion than a functionally equivalent single pass dispersive element.