Optical channel monitor having an array of micro-mirrors

• US 20030090756A1
• Filed: 09/25/2002
• Published: 05/15/2003
• Est. Priority Date: 09/25/2001
• Status: Abandoned Application

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.), Cidra Sarl (Nordic Cultural & Educational Foundation)
• Original Assignee: Cidra Sarl (Nordic Cultural & Educational Foundation)
• Inventors: Kersey, Alan D., Moon, John A., Dawson, Jay W., Dunphy, James R., Pinto, Joseph, Szczepanek, Paul, OʼKeefe, Christian
• Application Number:
  US10/255,133
• Publication Number:
  US 20030090756A1
• Time in Patent Office: Days
• US Class Current: 398/9
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/147 using averaging effects by spatially variable reflectivity on a microscopic level, e.g. polka dots, chequered or discontinuous patterns, or rapidly moving surfaces G02B27/1086 takes precedence
• 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 6/272 comprising polarisation means for beam splitting and combining
• CPC Class Codes: G02B 6/2773 Polarisation splitting or combining
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/29385 Channel monitoring, e.g. by tapping channel monitoring in optical transmission systems H04B10/07
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount

Abstract

A reconfigurable optical channel monitor selects and determines a parameter of desired optical channel(s) from and/or to an optical WDM input signal. The OCM 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 response to a control signal from a controller in accordance with a switching algorithm and an input command. A collimator, diffraction grating, and Fourier lens collectively converge the optical input channels onto the micro-mirrors array. The optical channel is focused onto a plurality of micro-mirrors. To select each input channel, a group of micro-mirrors associated with each desired input channel is tilted to reflect the desired input channel back along the return path to a photodetector and processing unit to determine a parameter of the selected input signal.

Claims

1. An optical channel monitor, comprising:

an optical arrangement having

a light dispersion element for separating an optical input signal into optical bands or channels and for directing one or more reflected optical bands or channels to provide an optical output signal, and

a spatial light modulator having a micro-mirror device with an array of micro-mirrors, a respective group of micro-mirrors selectively reflecting one or more optical bands or channels; and

a light detector for detecting the one or more reflected optical bands or channels in the optical output signal.

2. An optical channel monitor according to claim 1, wherein the one or more light dispersion elements include either a diffraction grating, an optical splitter, a holographic device, a prism, or a combination thereof.

3. An optical channel monitor according to claim 2, wherein the diffraction grating is a blank of polished fused silica or glass with a reflective coating having a plurality of grooves either etched, ruled or suitably formed thereon.

4. An optical channel monitor according to claim 2, wherein the diffraction grating is tilted and rotated approximately 90°

in relation to the spatial axis of the dispersed optical output signal.

5. An optical channel monitor according the claim 1, wherein the spatial light modulator is programmable for reconfiguring the optical channel monitor to drop and/or add a desired channel by changing a switching algorithm that drives the array of micro-mirrors.

6. An optical channel monitor according the 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.

7. An optical channel monitor according the claim 1, wherein the one or more optical signals include a wavelength division multiplexed (WDM) optical signal having a plurality of wavelengths and a corresponding plurality of optical bands or channels, each optical channel reflecting off a respective group of micro-mirrors of the micro-mirror device.

8. An optical channel monitor according the claim 1, wherein the spatial light modulator is 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 optical input signal.

9. An optical channel monitor according the claim 1, wherein the switching algorithm is based on the wavelength of the optical signal and the one or more optical bands or channels being detected.

10. An optical channel monitor according the claim 7, wherein the respective group of micro-mirrors are collectively tilted to reflect channels in the optical input signal.

11. An optical channel monitor according the 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 input signal, substantially parallel to the spatial axis of the optical input signal, or at an angle of 45 degrees in relation to the spatial axis.

12. An optical channel monitor according the claim 1, wherein the optical arrangement includes one or more optical portions that provide the one or more optical signals to the spatial light modulator.

13. An optical channel monitor according the claim 12, wherein the one or more optical portions include either one or more circulators, one or more waveguides, or a combination thereof.

14. An optical channel monitor according the claim 13, wherein the one or more optical portions provide the one or more optical signals to the spatial light modulator.

15. An optical channel monitor according the claim 13, wherein the one or more circulators includes a pair of circulators.

16. An optical channel monitor according the claim 13, wherein the one or more waveguides includes a pair of capillary tubes.

17. An optical channel monitor according the claim 13, wherein the one or more circulators includes a three port circulator.

18. An optical channel monitor according the claim 12, wherein the one or more optical portions include a pair of optical portions, including one optical portion for providing one or more optical signals to the spatial light modulator, and another optical portion for providing an optical signal to be detected to the detector.

19. An optical channel monitor according the claim 12, wherein the one or more optical portions include a collimator, a reflective surface, a dispersion device, a bulk lens, or a combination thereof.

20. An optical channel monitor according the claim 19, wherein the collimator includes either an aspherical lens, an achromatic lens, a doublet, a GRIN lens, a laser diode doublet, or a combination thereof.

21. An optical channel monitor according the claim 19, wherein the reflective surface includes a mirror.

22. An optical channel monitor according the claim 19, wherein the reflective surface is curved.

23. An optical channel monitor according the claim 19, wherein the bulk lens includes a Fourier lens.

24. An optical channel monitor according the claim 12, wherein the one or more optical portions provide the one or more optical as different channels having different wavelengths on the spatial light modulator.

25. An optical channel monitor according the claim 24, wherein the different channels have a desired cross-sectional geometry, including elliptical, rectangular, square or polygonal.

26. An optical channel monitor according the claim 24, wherein the spatial light modulator is configured so one group of channels is spaced at 100 GHz and another group of channels is spaced at 50 GHz.

27. An optical channel monitor according the claim 12, wherein the one or more optical portions further comprise a further optical portion for receiving the one or more optical signals from the spatial light modulator and providing these same optical signals back to the spatial light modulator.

28. An optical channel monitor according the claim 27, wherein the further optical portion includes a single reflective surface and lens arrangement.

29. An optical channel monitor according the claim 28, wherein a single lens is arranged between a reflective surface and the spatial light modulator.

30. An optical channel monitor according to claim 12, wherein the one or more optical portions include one or more optical PDL mitigating devices for minimizing polarization dependence loss (PDL).

31. An optical channel monitor according to claim 30, 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.

32. An optical channel monitor according to claim 31, wherein the one or more optical PDL mitigating devices include a pair of optical PDL mitigating devices.

33. An optical channel monitor according to claim 31, 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.

34. An optical channel monitor according to claim 33, 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.

35. An optical channel monitor according to claim 33, wherein the one or more optical PDL mitigating devices includes a λ

/4 plate.

36. An optical channel monitor according to claim 2, wherein the diffraction grating has a low PDL.

37. An optical channel monitor according to claim 12, wherein the optical arrangement includes a chisel prism having multiple faces for modifying the direction of the optical input signal.

38. An optical channel monitor according to claim 37, wherein the multiple faces include at least one front face, a rear face, a top face and a bottom face.

39. An optical channel monitor according to claim 37, wherein optical light from first or second optical portions 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 first or second optical portions.

40. An optical channel monitor according to claim 1, wherein the free optic configuration includes a lens and a grating arranged such that the lens is placed at a distance “

d”

from the grating that is shorter than focal length “

f”

of the lens.

41. An optical channel monitor according to claim 1, wherein the free optic configuration includes a lens and a grating arranged such that the lens is placed a distance “

d”

from the grating that is longer than focal length “

f”

of the lens.