Optical wavelength selective router
View Patent ↗A fiber-optical, wavelength selective switch, especially for channel routing with equalization and blocking applications. The input signals are converted to light beams having predefined polarizations ( 41 ). The beams are then laterally expanded ( 43 ), and then undergo spatial dispersion in the beam expansion plane. The different wavelength components are directed through a polarization rotation device, pixilated along the wavelength dispersion direction such that each pixel operates on a separate wavelength. Each beam is passed into a pixilated beam steering array ( 48 ), for directing each wavelength to a desired output port. The beam steering devices can be MEMS-based or Liquid crystal-based, or an LCOS array. When the appropriate voltage is applied to a pixel and its associated beam steering element, the polarization of the light passing through the pixel is rotated and the beam steered to couple to the selected output port.
1. A wavelength selective switch for switching multi-wavelength optical signals, the switch comprising:
a first port for receiving a multi-wavelength optical signal;
a plurality of output ports;
a wavelength dispersive element positioned to receive the optical signal for dispersing wavelength differentiated signal components of said optical signal;
an array of micro electro-mechanical system (MEMS) mirrors disposed such that at least one mirror corresponds to each signal component and is controllable to switch an output port for said signal component from a first output port to a second output port; and
an array of liquid crystal attenuators disposed such that at least one attenuator corresponds to each signal component and receives said signal component for selective rotation of a polarization of said signal component while the output port for said signal component is being switched from the first output port to the second output port so as to prevent cross-channel contamination.
2. The wavelength selective switch of claim 1 , wherein the output ports are linearly aligned and the arrays of MEMS mirrors and liquid crystal attenuators are linear arrays.
3. The wavelength selective switch of claim 1 , wherein said at least one attenuator rotates the polarization of the signal component received thereat when the signal component is directed to any of the output ports other than the second output port.
4. The wavelength selective switch of claim 3 , further comprising a birefringent crystal arranged adjacent to each output port to receive the signal component directed to the output port and configured to selectively displace the signal component passing therethrough in accordance with a polarization of the signal component.
5. The wavelength selective switch of claim 4 , wherein the signal component having a rotated polarization is displaced away from the output port.
6. A wavelength selective switch for switching multi-wavelength optical signals, the switch comprising:
a first port for receiving a multi-wavelength optical signal;
a plurality of output ports;
a wavelength dispersive element positioned to receive the optical signal for dispersing wavelength differentiated signal components of said optical signal;
an array of beam steering elements disposed such that at least one unique beam steering element receives each signal component and is controllable to switch an output port for said signal component from a first output port to a second output port; and
an array of liquid crystal attenuators disposed such that at least one unique attenuator receives each signal component for selective rotation of a polarization of said signal component while the output port for said signal component is being switched from the first output port to the second output port so as to prevent cross-channel contamination.
7. The wavelength selective switch of claim 6 , wherein the output ports are linearly aligned and the arrays of beam steering elements and liquid crystal attenuators are linear arrays, and the beam steering elements comprise micro electro-mechanical system mirrors.
8. The wavelength selective switch of claim 6 , wherein said at least one attenuator rotates the polarization of the signal component received thereat when the signal component is directed to any of the output ports other than the second output port.
9. The wavelength selective switch of claim 8 , further comprising a birefringent crystal arranged adjacent to each output port to receive the signal component directed to the output port and configured to selectively displace the signal component passing therethrough in accordance with a polarization of the signal component.
10. The wavelength selective switch of claim 9 wherein the signal component having a rotated polarization is displaced away from the output port.
11. A wavelength selective switch for switching multi-wavelength optical signals, the switch comprising:
a first port for receiving a multi-wavelength optical signal;
a plurality of output ports;
a wavelength dispersive element positioned to receive the optical signal and for dispersing wavelength differentiated signal components of said optical signal;
an array of micro electro-mechanical system (MEMS) mirrors disposed such that at least one unique mirror receives each signal component and is controllable to switch an output port for said signal component from a first output port to a second output port; and
an array of liquid crystal attenuators disposed such that at least one attenuator receives each signal component and rotates a polarization thereof to cause selective attenuation of said signal component.
12. The wavelength selective switch of claim 11 , wherein the output ports are linearly aligned and the arrays of MEMS mirrors and liquid crystal attenuators are linear arrays.
13. The wavelength selective switch of claim 11 , wherein said at least one attenuator rotates the polarization of the signal component received thereat when the signal component is directed to any of the output ports other than the second output port.
14. The wavelength selective switch of claim 13 , further comprising a birefringent crystal arranged adjacent to each output port to receive the signal component directed to the output port and configured to selectively displace the signal component passing therethrough in accordance with a polarization of the signal component.
15. The wavelength selective switch of claim 14 , wherein the signal component having a rotated polarization is displaced away from the output port.
16. A wavelength selective switch for switching multi-wavelength optical signals, the switch comprising:
a first port for receiving a multi-wavelength optical signal;
a plurality of output ports;
a wavelength dispersive element positioned to receive the optical signal for dispersing wavelength differentiated signal components of said optical signal;
an array of micro electro-mechanical system (MEMS) mirrors disposed such that at least one unique mirror receives each signal component is controllable to switch an output port for said signal component from a first output port to a second output port; and
an array of liquid crystal attenuators disposed such that at least one unique attenuator receives each signal component for selective rotation of a polarization of said signal component while the output port for said signal component is being switched from the first output port to the second output port so as to prevent cross-channel contamination and to cause selective attenuation of said signal component.
17. The wavelength selective switch of claim 16 , wherein the output ports are linearly aligned and the arrays of MEMS mirrors and liquid crystal attenuators are linear arrays.
18. The wavelength selective switch of claim 16 , wherein said at least one attenuator rotates the polarization of the signal component received thereat when the signal component is directed to any of the output ports other than the second output port.
19. The wavelength selective switch of claim 18 , further comprising a birefringent crystal arranged adjacent to each output port to receive the signal component directed to the output port and configured to selectively displace the signal component passing therethrough in accordance with a polarization of the signal component.
20. The wavelength selective switch of claim 19 , wherein the signal component having a rotated polarization is displaced away from the output port.