Optical detector configuration and utilization as feedback control in monolithic integrated optic and electronic arrangements

• US 7,327,911 B2
• Filed: 10/19/2005
• Issued: 02/05/2008
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Sioptical Inc. (Cisco Systems, Inc.)
• Inventors: Montgomery, Robert Keith, Patel, Vipulkumar, Gothoskar, Prakash, Shastri, Kalpendu, Piede, David, Nadeau, Mary
• Primary Examiner(s): Epps; Georgia
• Assistant Examiner(s): ELLIS, SUEZU Y
• Application Number:
  US11/253,456
• Publication Number:
  US 20060083144A1
• Time in Patent Office: 839 Days
• Field of Search: 250/227.11, 385 1- 3, 385/14, 385/31, 385/36, 385/37, 385/39, 385/40, 385/43, 385129-132, 398195-198, 398/213, 356/477
• US Class Current: 385/14
• CPC Class Codes: G02B 6/3586 Control or adjustment details, e.g. calibrating testing optical equipment G01M11/00
• CPC Class Codes: G02B 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• 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
• CPC Class Codes: G02F 1/0123 Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence
• CPC Class Codes: G02F 1/3136 of interferometric switch type
• CPC Class Codes: G02F 2201/58 Arrangements comprising a monitoring photodetector
• CPC Class Codes: G02F 2203/21 Thermal instability, i.e. DC drift, of an optical modulator; Arrangements or methods for the reduction thereof

Abstract

An improvement in the reliability and lifetime of SOI-based opto-electronic systems is provided through the use of a monolithic opto-electronic feedback arrangement that monitors one or more optical signals within the opto-electronic system and provides an electrical feedback signal to adjust the operation parameters of selected optical devices. For example, input signal coupling orientation may be controlled. Alternatively, the operation of an optical modulator, switch, filter, or attenuator may be under closed-loop feedback control by virtue of the inventive monolithic feedback arrangement. The feedback arrangement may also include a calibration/look-up table, coupled to the control electronics, to provide the baseline signals used to analyze the system'"'"'s performance.

Claims

1. A monolithic opto-electronic feedback arrangement for controlling the light in at least one optical element formed within a single crystal silicon surface layer (SOI layer) of a silicon-on-insulator (SOI) structure, the monolithic feedback arrangement formed within the same SOI structure and comprising

at least one optical photodetecting device disposed in the SOI layer to receive a portion of an optical signal propagating through the at least one optical element so as to measure the output optical signal power from the at least one optical element;

and

a control electronics module, responsive to the output signal from the at least one optical photodetecting device, for comparing the measured output signal power to predetermined values and applying a feedback control signal to the at least one optical element based upon the comparison.

2. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the arrangement further comprises an optical coupling waveguide disposed in the SOI layer between the at least one optical photodetecting device and the at least one optical element so as to tap off a portion of the propagating optical signal and couple the tapped-off portion into the input of the at least one optical photodetecting device.

3. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the at least one optical photodetecting device comprises an in-line optical photodetecting device disposed within the SOI layer along an output waveguide of the at least one optical element.

4. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the arrangement further comprises an A/D converter disposed between the output of the at least one optical photodetecting device and the input of the control electronics module for converting a measured analog signal value input a digital representation for use by the control electronics module.

5. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the arrangement further comprises a memory module including a look-up table disposed within the SOI structure and coupled to the control electronics module, the look-up table storing expected optical power values for use by the control electronics module.

6. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the arrangement further comprises

external control circuitry disposed beyond the SOI structure;

and

a communication interface for transmitting/receiving signals between the control electronics module and the external control circuitry.

7. The monolithic opto-electronic feedback arrangement as defined in claim 6 wherein the communication interface provides an input communication path for storing initialization values within the control electronics module.

8. The monolithic opto-electronic feedback arrangement as defined in claim 6 wherein the communication interface provides an output communication path for interrogating the control electronics module to determine its performance.

9. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the at least one optical photodetecting device comprises a pair of optical photodetecting devices.

10. The monolithic opto-electronic feedback arrangement as defined in claim 9 wherein a first optical photodetecting device of the pair of optical photodetecting devices is disposed along an input optical waveguide section with the SOI layer of the SOI structure and a second, remaining optical photodetecting device is disposed along an output optical waveguide section within the SOI layer of the SOI structure.

11. The monolithic opto-electronic feedback arrangement as defined in claim 10 wherein the optical element comprises at least an optical filter is disposed between the first and second optical photodetecting devices, the feedback arrangement utilized to perform wavelength filtering feedback control.

12. The monolithic opto-electronic feedback arrangement as defined in claim 10 wherein the optical element comprises at least an optical wavelength blocking device disposed between the first and second optical photodetecting devices, the feedback arrangement utilized to adjust the selected wavelength to be blocked.

13. The monolithic opto-electronic feedback arrangement as defined in claim 10 wherein the optical element comprises at least one variable optical attenuator disposed between the first and second optical photodetecting devices, the feedback arrangement utilized to perform attenuation adjustment feedback control.

14. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the optical element comprises an optical modulator, with the control electronics module output coupled to phase shifting sections of the optical modulator within the SOI layer of the SOI structure.

15. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the at least one optical element comprises a plurality of optical elements.

16. The monolithic opto-electronic feedback arrangement as defined in claim 15 wherein the arrangement further comprises an electronic selector for controlling the interface between the plurality of optical elements and the control electronics module.

17. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the arrangement further comprises at least one optical coupler, with the feedback arrangement used to adjust the coupling efficiency between the optical coupler and the at least one optical element.

18. The monolithic opto-electronic feedback arrangement as defined in claim 17 wherein the at least one optical coupler comprises an optical prism coupler, with the control electronics module output utilized to control the orientation and/or position of an optical signal with respect to an optical prism facet of the optical prism coupler.

19. The monolithic opto-electronic feedback arrangement as defined in claim 17 wherein the at least one optical coupler comprises an inverse tapered waveguide coupler.

20. The monolithic opto-electronic feedback arrangement as defined in claim 17 wherein the at least one optical coupler comprises an optical grating structure, with the feedback arrangement utilized to modify the period of the grating and adjust the associated optical coupling efficiency.

21. The monolithic opto-electronic feedback arrangement as defined in claim 17 wherein the at least one optical coupler comprises an input optical coupler.

22. The monolithic opto-electronic feedback arrangement as defined in claim 17 wherein the at least one optical coupler comprises an output optical coupler.

23. The monolithic opto-electronic feedback arrangement as defined in claim 1 wherein the at least one optical element is an optical switch.