Optical blocking filter having an array of micro-mirrors

• US 6,956,687 B2
• Filed: 12/19/2002
• Issued: 10/18/2005
• Est. Priority Date: 04/03/2001
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Cidra Sarl (Nordic Cultural & Educational Foundation)
• Inventors: Dunphy, James R., Kersey, Alan D., Putnam, Martin A., Davis, Michael A., Moon, John A., Pinto, Joseph, Sirkis, James S., Szczepanek, Paul
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): MARTINEZ, JOSEPH P
• Application Number:
  US10/327,695
• Publication Number:
  US 20030184843A1
• Time in Patent Office: 1,034 Days
• Field of Search: 359571-573, 359/900, 359290-292, 359/395, 359/297, 359/298, 359301-302, 359/315, 359/318, 359/320, 359/223, 359/850, 359/872, 359/224, 359/308, 359/618, 359/629, 359/634, 359/639, 398/45, 398/49, 398/51, 398/54, 398/83, 398/85, 398 87- 88, 398/79, 398/81, 385/33, 385/31, 385/39, 385 1- 3, 385 15- 18, 385/11, 385/24
• US Class Current: 359/223.1
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04Q 2011/0009 using wavelength filters
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A reconfigurable optical blocking filter deletes a desired optical channel(s) from an optical WDM input signal, and includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that tilt between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimators, diffraction grating, and Fourier lens, collectively collimate, separate and focus the optical input channels onto the array of micro-mirrors. The optical channel is focused on the micro-mirrors onto a plurality of micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels. To delete an input channel of the optical input signal, micro-mirrors associated with each desired input channel are tilted to reflect the desired input channel away from the return path.

Claims

1. An optical blocking filter for receiving an optical signal having one or more optical bands or channels, characterized in that

the optical blocking filter comprises a spatial light modulator having a micro-mirror device with an array of micro-mirrors for selectively deflecting the one or more optical bands or channels so that each optical band or channel is reflected off a respective plurality of micro-mirrors to eliminate a selected band or channel or a specified selection of bands or channels from the optical signal provided along an optical return path, wherein scattered light from a dropped signal is directed onto the micromirror device to reflect away from the return path.

2. An optical blocking filter according to claim 1, wherein the optical blocking filter comprises an optical arrangement for providing the optical signal along an optical path to the array of micromirrors.

3. An optical blocking filter according to claim 2, wherein the optical arrangement is a free optics arrangement.

4. An optical blocking filter according to claim 3, wherein the free optics arrangement provides the optical signal to the spatial light modulator, and also provide an optical output signal having each remaining band or channel reflected off the spatial light modulator.

5. An optical blocking filter according to claim 4, wherein the free optics arrangement includes either one or more circulators, one or more waveguides, or a combination thereof.

6. An optical blocking filter according to claim 5, wherein the one or more circulators includes a pair of circulators.

7. An optical blocking filter according to claim 6, wherein the one or more circulators includes a three port circulator.

8. An optical blocking filter according to claim 5, wherein the one or more waveguides includes a pair of capillary tubes.

9. An optical blocking filter according to claim 5, wherein the free optics arrangement comprise a further optical portion for receiving a reflected optical signal from the spatial light modulator and providing a re-reflected optical signal back to the spatial light modulator.

10. An optical blocking filter according to claim 9, wherein the re-reflected optical signal is reflected off the spatial light modulator and eliminated.

11. An optical blocking filter according to claim 9, wherein the further optical portion includes a bulk lens, a reflector, or a combination thereof.

12. An optical blocking filter according to claim 9, wherein the further optical portion includes a mirror for re-reflecting the optical signal back to the spatial light modulator.

13. An optical blocking filter according to claim 4, wherein the free optics arrangement includes a collimator, a reflective surface, a dispersion element, a bulk lens, or a combination thereof.

14. An optical blocking filter according to claim 13, wherein the collimator includes either an aspherical lens, an achromatic lens, a doublet, a GRIN lens, a laser diode doublet, or a combination thereof.

15. An optical blocking filter according to claim 13, wherein the reflective surface includes a mirror.

16. An optical blocking filter according to claim 15, wherein the reflective surface is curved.

17. An optical blocking filter according to claim 13, wherein the bulk lens includes a Fourier lens.

18. An optical blocking filter according to claim 13, wherein the dispersion element has a low PDL.

19. An optical blocking filter according to claim 13, wherein the dispersion element includes a diffraction grating, a tilted grating, an echelle grating, an etalon, a prism or a holographic optical device.

20. An optical blocking filter according to claim 3, wherein the free optics arrangement includes one or more optical PDL mitigating devices for minimizing polarization dependence loss (PDL).

21. An optical blocking filter according to claim 20, wherein one optical PDL mitigating device is arranged between a waveguide and a grating in the optical arrangement, and another optical PDL mitigating device is arranged between a grating and the spatial light modulator.

22. An optical blocking filter according to claim 20, wherein the one or more optical PDL mitigating devices include a pair of optical PDL mitigating devices.

23. An optical blocking filter according to claim 20, wherein the one or more optical PDL mitigating devices includes one optical PDL mitigating device having a polarization splitter for splitting each channel into a pair of polarized light beams and a rotator for rotating one of the polarized light beams of each optical channel.

24. An optical blocking filter according to claim 23, wherein the one or more optical PDL mitigating devices includes another optical PDL mitigating device having a rotator for rotating one of the previously rotated and polarized light beams of each optical channel and a polarization splitter for combining the pair of polarized light beams of each channel.

25. An optical blocking filter according to claim 20, wherein the one or more optical PDL mitigating devices includes a ·

/4 plate.

26. An optical blocking filter according to claim 2, wherein the optical arrangement includes a chisel prism having multiple faces for modifying the direction of the optical signal.

27. An optical blocking filter according to claim 26, wherein the multiple faces include at least a front face, a rear face, a top face and a bottom face.

28. An optical blocking filter according to claim 26, wherein the optical light from the free optics arrangement passes through one or more faces of the chisel prism, reflects off one or more internal surfaces of the chisel prism, reflects off the spatial light modulator, again reflects off the one or more internal surfaces of the chisel prism, and passes back to the free optics arrangement.

29. An optical blocking filter according to claim 2, wherein the optical arrangement includes a field correction lens for respectively compensating for the one or more channels reflecting of the spatial light modulator.

30. An optical blocking filter according to claim 1, wherein the spatial light modulator is programmable for reconfiguring the optical blocking filter to eliminate each band or channel by changing a switching algorithm that drives the array of micro-mirrors.

31. An optical blocking filter according to claim 30, wherein the spatial light modulator is selectively reconfigurable by statically or dynamically modifying the switching algorithm to accommodate different channel spacing, the shape of the light beam, or the center wavelength of the light beam of the optical signal.

32. An optical blocking filter according to claim 30, wherein the switching algorithm is based on the wavelength of the optical signal and the one or more optical bands or channels being eliminated.

33. An optical blocking filter according to claim 30, wherein the spatial light modulator is configured so one group of optical channels is spaced at 100 Hz and another group of optical channels is spaced at 50 Hz.

34. An optical blocking filter according to claim 1, wherein the array of micro-mirrors includes a multiplicity of micro-mirrors that are separately controllable for tilting on an axis depending on a control signal in accordance with a switching algorithm.

35. An optical blocking filter according to claim 1, wherein the optical signal is a wavelength division multiplexed (WDM) optical signal having a plurality of wavelengths and a corresponding plurality of optical bands or channels.

36. An optical blocking filter according to claim 1, wherein each micro-mirror is tiltable in either a first position or a second position along an axis either substantially parallel to the spectral axis of the optical signal, parallel to the spatial axis of the optical signal, or at an angle of 45 degrees in relation to the spatial axis.

37. An optical blocking filter according to claim 1, wherein the one or more optical bands or channels have a desired cross-sectional geometry, including an elliptical, a rectangular, a square or a polygonal shape.

38. An optical blocking filter according to claim 1, wherein the optical arrangement includes a first free optics arrangement that provides the optical signal to the spatial light modulator, and a second free optics arrangement that provides an eliminated optical signal from the spatial light modulator.

39. An optical blocking filter according to claim 38, wherein the common free optics arrangement includes

a first optical circulator for providing a first optical signal to the first optical blocking filter and for providing a first optical output signal with first remaining optical bands or channels;

and

a second optical circulator for providing a second optical signal to the second optical blocking filter and for providing a second optical output signal with second remaining optical bands or channels.

40. An optical blocking filter according to claim 1, wherein the optical blocking filter includes a first optical blocking filter and a second optical blocking filter, each sharing a common free optics arrangement.

41. An optical blocking filter according to claim 1, wherein the optical arrangement comprises:

one or more polarization separators for separating the optical signal into a P state optical signal and an S state optical signal, and for combining a P state optical return signal and an S state optical return signal into an optical output signal; and

a ½

·

wave plate for rotating the P state optical signal into a rotated S state optical signal, and for rotating an S state optical return signal into the P state optical return signal.

42. An optical blocking filter according to claim 41, wherein the one or more polarization separators include a Wollistan prism, a polarization beam splitter, a fiber coupler or some combination thereof.

43. An optical blocking filter according to claim 1, wherein the optical arrangement is arranged in relation to an optical axis and the micromirror surfaces when the array of micromirrors is the neutral position are non-orthogonal in relation to the optical axis.

44. An optical blocking filter according to claim 1, wherein the optical arrangement is arranged on an optical axis and the micromirror surfaces when the array of micromirrors is in the neutral position are orthogonal to the optical axis so during a failure of the spatial light modulator the optical signal is reflected back along the optical return path and propagated through the optical blocking filter.

45. An optical blocking filter according to claim 1, wherein the optical signal includes a plurality of channels, each having at least one respective spectral band or section.

46. An optical blocking filter according to claim 1, wherein the optical signal includes at least one channel having respective spectral bands or sections arranged in non-uniform spectral arrays on the array of micro-mirror.

47. An optical blocking filter according to claim 46, wherein the non-uniform spectral arrays include arrays having a different length, width, number or combination thereof on the array of micro-mirrors.

48. An optical blocking filter according to claim 1, wherein the optical signal includes a plurality of channels that are non-linearly disposed on the array of micro-mirrors.

49. An optical blocking filter for receiving an optical signal having one or more optical bands or channels, characterized in that

the optical blocking filter comprises a spatial light modulator having a micro-mirror device with an array of micro-mirrors for selectively deflecting the one or more optical bands or channels to a reflecting device, which re-reflects the one or more optical bands or channels back to the spatial light modulator for re-deflecting the one or more optical bands or channels, in order to eliminate a selected band or channel or a specified selection of bands or channels from the optical signal provided along an optical return path, wherein scattered light from a dropped signal is directed onto the micromirror device to reflect away from the return path.

50. An optical blocking filter according to claim 49, wherein the reflecting device is a mirror.

51. An optical blocking filter according to claim 49, wherein each optical band or channel is reflected off a respective plurality of micro-mirrors.