Single-pole optical wavelength selector

A wavelength selective optical switch comprising:

• a first birefringent element for receiving input light having a plurality of wavelength components, said element adapted to decompose said input light into two light beams having essentially the same predetermined polarization direction;
• a beam expanding device for expanding said two light beams in a predetermined plane;
• a first dispersive element receiving said expanded two light beams, and dispersing different wavelength components of said expanded light beams in said predetermined plane;
• a first at least one optical element for focusing said dispersed wavelength components of said expanded light beams onto a focal plane;
• a polarization rotation element located essentially at said focal plane, said polarization rotation element being pixelated generally along the direction of said dispersion such that separate pixels are associated with separate wavelength components of said expanded light, at least one pixel of said polarization rotation element being operative to rotate the polarization of light passing through said pixel according to a control signal applied to said pixel;
• a second at least one optical element for collecting said dispersed wavelength components of said expanded light beams after passing through said polarization rotation element, to regenerate two output expanded light beams;
• a second dispersive element receiving said two output expanded light beams and operative to combine them into two multi-wavelength output light beams;
• and
• a reflective element disposed downstream of said second dispersive element operative to reflect said output light beams back through said switch along their input path but in a reverse direction, and wherein only those wavelength components of light reflected back through said at least one pixel having said predetermined polarization direction are recombined by said first birefringent element for transmission back out of said switch.

A wavelength selective optical switch comprising:

• a birefringent element for receiving input light having a plurality of wavelength components, said element adapted to decompose said input light into two light beams having essentially the same predetermined polarization direction;
• a beam expanding device for expanding said two light beams in a predetermined plane;
• a dispersive element receiving said expanded two light beams, and dispersing different wavelength components of said expanded light beams in said predetermined plane;
• a first at least one optical element for focusing said dispersed wavelength components of said expanded light beams onto a focal plane;
• a polarization rotation element located essentially at said focal plane, said polarization rotation element being pixelated generally along the direction of said dispersion such that separate pixels are associated with separate wavelength components of said expanded light beams, at least one pixel of said polarization rotation element being operative to rotate the polarization of light passing through said pixel according to a control signal applied to said pixel;
• a second at least one optical element for collecting said dispersed wavelength components of said expanded light beams after passing through said polarization rotation element, to regenerate two output expanded light beams;
• a third at least one optical element for collimating said regenerated two output expanded light beams;
• and
• a reflective element disposed in said collimated regenerated two output expanded light beams, and operative to reflect said output light beams back through said switch essentially along their input path but in a reverse direction, and wherein only those wavelength components of said light reflected back through said at least one pixel having said predetermined polarization direction are recombined by said birefringent element for transmission back out of said switch.

A wavelength selective optical switch comprising:

• a birefringent element for receiving input light having a plurality of wavelength components, said element adapted to decompose said input light into two light beams having different polarizations;
• a beam expanding device for expanding said two light beams having different polarizations in a predetermined plane;
• a dispersive element receiving said expanded two light beams having different polarizations, and dispersing different wavelength components of said expanded two light beams in said predetermined plane;
• at least one optical element for focusing said dispersed wavelength components of said expanded two light beams of different polarizations onto a focal plane;
• a polarization rotation element located essentially at said focal plane, said polarization rotation element being pixelated generally along the direction of said dispersion such that separate pixels are associated with separate wavelength components of said two light beams, at least one pixel of said polarization rotation element being operative to rotate the polarization of light passing through said pixel according to a control signal applied thereto;
• and
• a reflective surface disposed in proximity to and after said polarization rotation element, such that said wavelength components of said two light beams passing through said at least one pixel of said polarization rotation element are reflected back through said at least one pixel.

A wavelength selective optical switch comprising:

• a birefringent element for receiving input light having a plurality of wavelength components from a first input port, said element adapted to decompose said input light into two light beams having the same predetermined polarization;
• a polarized beam splitting device receiving said two light beams having the same predetermined polarization;
• a beam expanding device for expanding in a predetermined plane, said two light beams after transmission through said polarized beam splitter;
• a dispersive element receiving said expanded two light beams, and dispersing different wavelength components of said expanded two light beams in said predetermined plane;
• at least one optical element for focusing said dispersed wavelength components of said expanded two light beams onto a focal plane;
• a polarization rotation element located essentially at said focal plane, said polarization rotation element being pixelated generally along the direction of said dispersion such that separate pixels are associated with separate wavelength components of said two light beams, at least one pixel of said polarization rotation element being operative to rotate the polarization of light passing through said pixel according to a control signal applied thereto;
• a reflective surface disposed in proximity to and after said polarization rotation element, such that wavelength components of said two light beams passing through said at least one pixel of said polarization rotation element are reflected back through said at least one pixel;
• and
• and a second birefringent element disposed at a reflective output of said polarized beam splitter, for receiving two light beams reflected in said polarized beam splitter and having like but orthogonal polarization to said predetermined polarization, said second birefringent element being adapted to recompose said two light beams into an output light beam, such that those wavelength components of said two light beams reflected back through said polarization rotation element having their polarization direction rotated by said at least one pixel are output from said switch at a first output port.

A method of constructing a reflective wavelength selective optical switch, comprising the steps of:

• providing a wavelength selective optical switch utilizing a pixelated polarization rotation element to select a wavelength component of an optical signal to be switched by rotation of the direction of polarization of said wavelength component impinging on a pixel of said polarization rotation element;
• disposing a birefringent wedge after said polarization rotation element, such that said wavelength component of said optical signal passing through said birefringent wedge is deviated at an angle dependent on the polarization direction of said wavelength component;
• and
• providing a reflective surface after said birefringent wedge, aligned such that only if said wavelength component has a predetermined polarization, does it impinge on said reflective surface at normal incidence, and is reflected back along its incident path.

A method of constructing a reflective wavelength selective optical switch, comprising the steps of:

• providing a wavelength selective optical switch utilizing a pixelated polarization rotation element to select a wavelength component of an optical signal to be switched by rotation of the direction of polarization of said wavelength component impinging on a pixel of said polarization rotation element;
• disposing a linear polarizer element after said polarization rotation element, such that transmission of said wavelength component of said optical signal passing though said linear polarizer element is dependent on the polarization direction of said wavelength component;
• and
• disposing a reflective surface after said linear polarizer element, such that only if said wavelength component has a predetermined polarization is it reflected back along its incident path.

A wavelength selective optical switch, comprising:

• a first birefringent device for receiving input light having a plurality of wavelength components, said device adapted to decompose said input light into two light beams having predefined polarizations;
• a first dispersive element receiving said two light beams having predefined polarizations, and dispersing different wavelength components of said light beams;
• a first at least one optical element for focusing said dispersed wavelength components of said two light beams of predefined polarizations onto a focal plane;
• a polarization rotation element located essentially at said focal plane, said polarization rotation element being pixelated generally along the direction of said dispersion such that separate pixels are associated with separate wavelength components of said light beams, at least one pixel of said polarization rotation element being operative to rotate the polarization of light passing through said pixel according to a control signal applied to said pixel;
• a reflective surface disposed in proximity to and after said polarization rotation element, said reflective surface being aligned such that said light beams are reflected back through said pixel and along output paths spatially distinct from the paths of incidence of said light beams;
• and
• an output section for outputting said light, said output path comprising at least one polarization selective device receiving said light beams after passing through said pixel, and transmitting only light having a predetermined polarization, such that transmission of said light beams is determined by said control signal.