Wavelength-selective switch and equalizer

• US 7,043,110 B1
• Filed: 12/10/2002
• Issued: 05/09/2006
• Est. Priority Date: 12/10/2002
• Status: Active Grant

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Carlisle, Clinton B., Trisnadi, Jahja I.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): EL SHAMMAA, MARY A
• Application Number:
  US10/315,792
• Time in Patent Office: 1,246 Days
• Field of Search: 385/18, 385/24, 385/16, 359/290, 359/291
• US Class Current: 385/16
• CPC Class Codes: G02B 6/272 comprising polarisation means for beam splitting and combining
• CPC Class Codes: G02B 6/2793 Controlling polarisation dependent loss, e.g. polarisation insensitivity, reducing the change in polarisation degree of the output light even if the input polarisation state fluctuates
• CPC Class Codes: G02B 6/29302 based on birefringence or polarisation, e.g. wavelength dependent birefringence, polarisation interferometers
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/29397 Polarisation insensitivity
• CPC Class Codes: G02B 6/3516 the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3592 Means for removing polarization dependence of the switching means, i.e. polarization insensitive switching light guides coupling with polarization selective and adjusting means G02B6/27
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Abstract

One embodiment disclosed relates to a method for wavelength-selective switching and equalization. The method includes dispersing an incoming multiplexed signal into wavelength components, focusing the wavelength components onto different portions of a controllable light diffractor array, and controllably diffracting each wavelength component such that each said component is individually attenuated and arrives at the individually selected output without substantial crosstalk between the outputs. Another embodiment relates to a wavelength-selective switching device with integrated equalizer functionality. Another embodiment relates to an optical apparatus for wavelength-selective switching and equalization. The apparatus includes a means for controllably diffracting each wavelength component of a multiplexed input such that each said component is controllably attenuated and directed to arrive at an individually selected output.

Claims

1. A method for wavelength-selective switching and equalization, the method comprising:

dispersing an incoming multiplexed signal into wavelength components;

focusing the wavelength components onto different portions of a controllable light diffractor; and

controllably diffracting each wavelength component such that each component is individually modulated and arrives at an individually selected output without substantial crosstalk between the outputs,

wherein diffracting each wavelength component is performed using separate groups of reflective members,

wherein each group is divided into a first subgroup and a second subgroup, each subgroup having a same number of at least two reflective members,

wherein the reflective members of the first subgroup are spaced in equally-spaced steps, the reflective members of the second subgroup are spaced in the same equally-spaced steps, and the second subgroup is displaced from the first subgroup by an intersubgroup displacement,

wherein said spacing minimizes crosstalk between the outputs, and

wherein the intersubgroup displacement is controllably varied to modulate a diffraction efficiency for equalization while said crosstalk remains at a minimum for switching functionality.

2. The method of claim 1, wherein said diffraction efficiency is at a minimum value when the intergroup displacement is zero.

3. The method of claim 1, wherein said diffraction efficiency is at a maximum value when the intergroup displacement is λ

divided by 4, where λ

is a wavelength of the wavelength component received by that group of reflective members.

4. A wavelength-selective switching apparatus with integrated equalizer functionality, the apparatus comprising:

an input for receiving an incoming multiplexed signal having a plurality of wavelength components;

a first output for transmitting a first outgoing signal;

a second output for transmitting a second outgoing signal; and

an optical system coupled to receive the incoming multiplexed signal and configured to switch each of the wavelength components to an individually selected output, wherein the optical system is further configured to individually attenuate each of the wavelength components by a controllable amount,

wherein the optical system comprises a grating configured to disperse the incoming multiplexed signal into the plurality of wavelength components and a controllable light diffractor array configured to receive the plurality of wavelength components and controllably diffract each wavelength component such that each of the components arrives at the individually selected output,

wherein the controllable light diffractor array comprises a plurality of light diffraction devices,

wherein each light diffraction device comprises a group of 2N reflective members which is divided into a first subgroup of N reflective members and a second subgroup of N reflective members, where N is an integer of at least two,

wherein the reflective members of the first subgroup are spaced in steps, the reflective members of the second subgroup are spaced in steps, and the second subgroup is displaced from the first subgroup by an intersubgroup displacement, and

wherein the intersubgroup displacement controls modulation of the wavelength component received by that light diffraction device for equalization without inducing crosstalk between the first output and the second output for switching functionality.

5. The apparatus of claim 4, wherein said spacing between the steps minimizes crosstalk between the first output and the second output.

6. The apparatus of claim 4, wherein said spacing between steps is about λ

divided by 4N, where λ

is a wavelength of the wavelength component received by that light diffraction device.

7. The apparatus of claim 4, further comprising a Fourier transform lens adapted to focus the plurality of wavelength components onto different portions of the controllable light diffractor array.

8. The apparatus of claim 4, further comprising a polarization diversity module coupling the optical system to the input and the outputs.

9. The apparatus of claim 8, wherein the polarization diversity module is configured to reduce polarization-dependent loss of the optical system.

10. The apparatus of claim 4, wherein said diffraction efficiency is at a minimum value when the intergroup displacement is zero.

11. The apparatus of claim 4, wherein said diffraction efficiency is at a maximum value when the intergroup displacement is λ

divided by 4, where λ

is a wavelength of the wavelength component received by that light diffraction device.