Diffractive light modulator-based dynamic equalizer with integrated spectral monitor

• US 7,054,515 B1
• Filed: 05/30/2002
• Issued: 05/30/2006
• Est. Priority Date: 05/30/2002
• 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., Cejna, Vlastimil
• Primary Examiner(s): BOVERNICK, RODNEY B
• Assistant Examiner(s): Pak, Sung
• Application Number:
  US10/159,330
• Time in Patent Office: 1,461 Days
• Field of Search: 385/14, 385/25, 385/48, 385/140
• US Class Current: 385/14
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• 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 6/29391 Power equalisation of different channels, e.g. power flattening
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: H04B 10/25073 using spectral equalisation, e.g. spectral filtering

Abstract

An integrated device of the present invention comprises free-space optics, a bi-directional multiplexor/de-multiplexor, a diffractive light modulator, a beam splitter, an optical performance monitor, and a controller. The free-space optics collimate, transform and image optical signals including a range of component wavelength signals. The bi-directional multiplexor/de-multiplexor de-multiplexes a wavelength division multiplexed signal into the component wavelength signals and multiplexes equalized component wavelength signals into an equalized wavelength division multiplexed signal. The diffractive light modulator selectively equalizes each component wavelength signal. The beam splitter is optically coupled in free-space to the diffractive light modulator for receiving the equalized component wavelength signals and re-directing a representative portion of each of the equalized component wavelength signals. The optical performance monitor receives and detects relative power levels of each representative portion of the equalized component wavelength signals. The controller receives the detected power levels, provides feedback signals and dynamically modulates the diffractive light modulator in response thereto to maintain a desired level of each of the equalized component wavelength signals.

Claims

1. An integrated apparatus for selectively adjusting power levels of component signals of a wavelength division multiplexed signal, the apparatus comprising:

a. a diffractive light modulator configured to receive de-multiplexed component signals and to selectively direct each of the received component signals into a first mode and a second mode, thereby forming equalized component signals; and

b. an optical array detector optically coupled to the diffractive light modulator for collecting a representative portion of each of the equalized component signals and for detecting relative power levels associated with each collected representative portion, wherein the power levels are detected for dynamically configuring the diffractive light modulator to maintain a desired level of power in the first mode for each equalized component signal relative to each other,

whereby the diffractive light modulator and the optical array detector are integrally coupled to form the integrated apparatus.

2. The apparatus according to claim 1 wherein the diffractive light modulator and the optical array detector are integrally coupled using free-space optics.

3. The apparatus according to claim 1 further comprising a controller electrically coupled to the optical array detector and the diffractive light modulator for receiving the detected power levels and sending control signals for dynamically configuring the diffractive light modulator.

4. The apparatus according to claim 1 further comprising a demultiplexer configured to de-multiplex the wavelength division multiplexed signal into the component signals, including the first wavelength signal and the second wavelength signal, and a multiplexer configured to multiplex the equalized component signals into an output signal.

5. The apparatus according to claim 1 further comprising a beam splitter optically coupled in free-space to the diffractive light modulator for receiving the first and second equalized wavelength signals and for re-directing a representative portion of each of the equalized component signals.

6. An integrated apparatus for selectively adjusting power levels of component signals of a wavelength division multiplexed signal including a first wavelength signal and a second wavelength signal, the apparatus comprising:

a. a diffractive light modulator with a first pixel configured to receive the first wavelength signal and a second pixel configured to receive the second wavelength signal, wherein each pixel is controllable to selectively direct a received signal in a first mode and a second mode, thereby forming a first equalized wavelength signal and a second equalized wavelength signal;

b. an optical array detector optically coupled to each pixel using free-space optics for collecting a representative portion of the first equalized wavelength signal and a representative portion of the second equalized wavelength signal and for detecting relative power levels associated with each collected representative portion; and

c. a controller electrically coupled to the optical array detector and the diffractive light modulator for receiving the detected power levels from the optical performance monitor and for dynamically modulating the first and the second pixels of the diffractive light modulator to maintain a desired level of power in the first mode for each pixel relative to each other,

whereby the diffractive light modulator, the optical performance monitor and the controller are integrally coupled to form the integrated apparatus.

7. The apparatus according to claim 6 wherein the optical array detector comprises an imaging lens and a photo diode array including a first photo diode and a second photo diode wherein the imaging lens directs the representative portion of the first equalized wavelength signal onto the first photo diode and directs the representative portion of the second equalized wavelength signal onto the second photo diode such that the first and second photo diodes detect the power levels proportional to the first and second equalized wavelength signals, respectively.

8. The apparatus according to claim 7 wherein the optical array detector is optically coupled to each pixel by a pick-up beam splitter such that the pick-up beam splitter intersects each equalized wavelength signal in free-space and directs the representative portion of the first equalized wavelength signal and the representative portion of the second wavelength signal to the imaging lens of the optical performance monitor.

9. The apparatus according to claim 6 wherein the first wavelength signal, the second wavelength signal, the first equalized wavelength signal and the second equalized wavelength signal are directed using free space optics.

10. The apparatus according to claim 6 wherein the first mode comprises a reflection mode and further wherein the second mode comprises a diffraction mode.

11. The apparatus according to claim 6 further comprising a demultiplexer configured to de-multiplex the wavelength division multiplexed signal into the component signals, including the first wavelength signal and the second wavelength signal, and a multiplexer configured to multiplex the first and second equalized wavelength signals into an output signal.

12. The apparatus of claim 11 wherein the multiplexer and the demultiplexer comprise separate components.

13. The apparatus of claim 11 wherein the multiplexer and the demultiplexer comprise a bi-directional multiplexer/demultiplexer.

14. The apparatus of claim 11 wherein the demultiplexer comprises a dispersion device.

15. The apparatus of claim 14 wherein the dispersion device comprises a prism.

16. The apparatus of claim 14 wherein the dispersion device comprises a grating.

17. The apparatus of claim 7 wherein the imaging lens of the optical array detector comprises a lens array.

18. An integrated apparatus for selectively adjusting power levels of component signals of a wavelength division multiplexed signal including a first wavelength signal and a second wavelength signal, the apparatus comprising:

a. means for equalizing the component signals comprising a first pixel configured to receive the first wavelength signal and a second pixel configured to receive the second wavelength signal, wherein each pixel is controllable to selectively direct a received signal into a first mode and a second mode, thereby forming a first equalized wavelength signal and a second equalized wavelength signal;

b. means for collecting a representative portion of the first equalized wavelength signal and a representative portion of the second equalized wavelength signal, wherein the means for collecting is coupled to the means for equalizing using free-space optics;

c. means for detecting relative power levels associated with each collected representative portion; and

d. means for controlling the first and the second pixels in response to the detected power levels to maintain a desired level of power in the first mode for each pixel relative to each other,

whereby the means for equalizing, the means for collecting, the means for detecting and the means for controlling are integrally coupled to form the integrated apparatus.