Dual modulator wavelength-selective switch and equalizer

• US 6,876,475 B1
• Filed: 01/17/2003
• Issued: 04/05/2005
• Est. Priority Date: 01/17/2003
• Status: Expired due to Term

• 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., Corrigan, Robert W.
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US10/346,757
• Time in Patent Office: 809 Days
• Field of Search: 359/237, 359/223, 359/224, 359/290, 359/291, 359/559, 359/562, 385/16, 385/17, 385/18, 385/19
• US Class Current: 359/237
• CPC Class Codes: G02B 6/2713 cascade of polarisation selective or adjusting operations
• 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 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29313 characterised by means for controlling the position or direction of light incident to or leaving the diffractive element, e.g. for varying the wavelength response switching G02B6/35
• CPC Class Codes: G02B 6/29314 by moving or modifying the diffractive element, e.g. deforming
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• 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

Abstract

One embodiment pertains to an apparatus for wavelength-selective switching and equalization of an incoming multiplexed signal having a plurality of wavelength components. The apparatus includes a first controllable light modulator, a second controllable light modulator, and a lens system. The first controllable light modulator controllably deflects a first set of the wavelength components and controllably reflects a second set of the wavelength components. The wavelength components in the second set are mapped onto separate sections of the second controllable light modulator by the lens system and are controllably reflected by the second controllable light modulator.

Claims

1. A method for wavelength-selective switching and equalization of an incoming multiplexed signal the method comprising:

dispersing a plurality of wavelength components of the incoming multiplexed signal onto separate sections of a first controllable light modulator;

controllably deflecting a first set of the wavelength components and controllably reflecting a second set of the wavelength components using the first controllable light modulator;

mapping the wavelength components in the second set onto separate sections of a second controllable light modulator;

equalizing the wavelength components in the first set by using the first controllable light modulator to control a first order diffraction magnitude for each of the wavelength components in the first set;

suppressing the wavelength components in the first set by using the second controllable light modulator; and

equalizing the wavelength components in the second set by using the second controllable light modulator to control a zero order diffraction magnitude for each of the wavelength components in the second set.

2. The method of claim 1, wherein the wavelength components in the first set correspond to channels to be dropped, wherein the wavelength components in the second set correspond to channels to be expressed, and wherein insertion loss of the channels to be expressed is less than the insertion loss of the channels to be dropped.

3. A The method of claim 1, further comprising:

dispersing the incoming multiplexed signal into the plurality of wavelength components using a first diffraction grating; and

retro-diffracting the wavelength components in the first set using the first diffraction grating to form a re-multiplexed signal.

4. The method of claim 3, further comprising:

receiving the incoming multiplexed signal by way of a circulator; and

sending the re-multiplexed signal to an output line by way of the circulator.

5. The method of claim 3, further comprising:

receiving the incoming multiplexed signal through a polarization diversity module; and

sending the re-multiplexed signal through the polarization diversity module.

6. The method of claim 1, further comprising:

controllably reflecting the wavelength components in the second set using the second controllable light modulator; and

diffracting the wavelength components in the second set using a second diffraction grating to form a re-multiplexed signal.

7. The method of claim 6, further comprising:

sending the re-multiplexed signal through a polarization diversity module.

8. An apparatus for wavelength-selective switching and equalization of an incoming multiplexed signal having a plurality of wavelength components, the apparatus comprising:

a first controllable light modulator for controllably deflecting a first set of the wavelength components and controllably reflecting a second set of the wavelength components;

a second controllable light modulator for controllably reflecting the wavelength components in the second set; and

a lens system for mapping the wavelength components in the second set onto separate sections of the second controllable light modulator,

wherein the first controllable light modulator equalizes the wavelength components in the first set by controlling a first order diffraction magnitude for each of the wavelength components in the first set, and

wherein the second controllable light modulator equalizes the wavelength components in the second set and suppresses the wavelength components in the first set by controlling a zero order diffraction magnitude for each of said wavelength components.

10. The apparatus of claim 8, further comprising:

a first diffraction grating for dispersing the incoming multiplexed signal into the plurality of wavelength components; and

a fourier transform lens for focusing the plurality of wavelength components onto separate sections of the first controllable light modulator.

11. The apparatus of claim 10, wherein the lens system comprises the fourier transform lens and an inverse fourier transform lens, and wherein the lens system maps the wavelength components in the second set with unit magnification.

12. The apparatus of claim 10, wherein the wavelength components in the first set are retro-diffracted using the first diffraction grating to form a re-multiplexed signal.

13. The apparatus of claim 12, further comprising:

a circulator for receiving the incoming multiplexed signal and for sending the re-multiplexed signal to an output line.

14. The apparatus of claim 12, further comprising:

a polarization diversity module through which is transmitted the incoming multiplexed signal and the re-multiplexed signal.

15. The apparatus of claim 10, further comprising:

a second diffraction grating for diffracting the wavelength components in the second set so as to form a re-multiplexed signal.

16. The apparatus of claim 15, further comprising:

a polarization diversity module through which is transmitted the re-multiplexed signal.

9. The apparatus of 8, wherein the wavelength components in the first set correspond to channels to be dropped, wherein the wavelength components in the second set correspond to channels to be expressed, and wherein insertion loss of the channels to be expressed is less than the insertion loss of the channels to be dropped.

17. An apparatus for wavelength-selective switching and equalization of an incoming multiplexed signal, the apparatus comprising:

a first controllable means for controllably deflecting a first set of the wavelength components and controllably reflecting a second set of the wavelength components;

a second controllable means for controllably reflecting the wavelength components in the second set; and

means for mapping the wavelength components in the second set onto separate sections of the second controllable means,

wherein the first controllable means equalizes the wavelength components in the first set by controlling a first order diffraction magnitude for each of the wavelength components in the first set, and

wherein the second controllable means equalizes the wavelength components in the second set by controlling a zero order diffraction magnitude for each of the wavelength components in the second set and further suppresses the wavelength components in the first set by minimizing the zero order diffraction magnitude for each of the wavelength components in the first set.