Fiber optic attenuation systems, methods of fabrication thereof and methods of attenuation using the same

• US 6,370,312 B1
• Filed: 04/11/2000
• Issued: 04/09/2002
• Est. Priority Date: 02/20/1998
• Status: Expired due to Fees

• Current Assignee: Molecular Optoelectronics Corporation
• Original Assignee: Molecular Optoelectronics Corporation
• Inventors: McCallion, Kevin J., Jameson, Gary O., Wagoner, Gregory A.
• Primary Examiner(s): PALMER, PHAN T H
• Application Number:
  US09/529,435
• Time in Patent Office: 728 Days
• Field of Search: 385/27, 385/28, 385/30, 385/37, 385/39, 385/140, 385/141, 372/20, 372/99, 372/102
• US Class Current: 385/140
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/2826 using mechanical machining means for shaping of the couplers, e.g. grinding or polishing grinding, polishing in general B24
• CPC Class Codes: G02F 1/0118 by controlling the evanescent coupling of light from a fibre into an active, e.g. electro-optic, overlay
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence

Abstract

Controllable fiber optic attenuators and attenuation systems (100) are disclosed for controllably extracting optical energy from a fiber optic (30), and therefore attenuating the optical signal being transmitted through the fiber optic (30). In one aspect, material is removed from a portion of the optical fiber (30), thereby exposing a surface through which optical energy can be extracted. A controllable material is formed over the surface for controllably extracting optical energy according to a changeable stimulus applied thereto, which affects the refractive index thereof. In an improved embodiment, a controllable material is formed over the exposed surface for controlling the amount of optical energy extracted from the fiber optic, and a bulk material is formed over the controllable material, into which the extracted optical energy is radiated.

Claims

1. An attenuation system comprising:

a controllable attenuator, arranged with respect to a portion of a fiber optic, the portion of the fiber optic having a side surface thereof through which at least some of the optical energy can be extracted, the attenuator including a controllable material formed over the surface for controllably extracting the optical energy in accordance with a changeable stimulus applied to the controllable material which affects the refractive index thereof;

a level circuit for providing a feedback stimulus having a value related to at least a portion of the optical energy transmitted in the fiber optic; and

a control circuit coupled to the controllable attenuator for controlling an amount of the changeable stimulus applied to the controllable material in accordance with the feedback stimulus.

2. The attenuation system of claim 1, wherein the level circuit includes:

a first sensing circuit for sensing an amount of optical energy transmitted in said fiber optic prior to any extraction thereof by said controllable attenuator;

a second sensing circuit for sensing an amount of optical energy transmitted in said fiber optic following any extraction thereof by said controllable attenuator; and

a circuit for determining a level of optical energy extracted from said fiber optic according to the sensed amounts of optical energy prior to and following the extraction thereof by said controllable attenuator, and providing the feedback stimulus to the control circuit based on said level of optical energy extracted.

3. The attenuation system of claim 2, wherein the control circuit includes a comparing circuit for comparing the feedback stimulus and a desired level stimulus applied thereto, and, based on any difference therebetween, changing the value of the control stimulus provided to the controllable attenuator.

4. The attenuation system of claim 3, wherein the changeable stimulus applied to the controllable material comprises temperature or voltage, and wherein the control circuit provides a control stimulus to said controllable attenuator to change the temperature or voltage applied to said controllable material.

5. The attenuation system of claim 4, wherein:

the controllable attenuator includes a controlling element, having an input for receiving said control stimulus from said control circuit, and arranged with respect to the controllable material to change the temperature, or voltage, and therefore the refractive index thereof in accordance with the control stimulus.

6. The attenuation system of claim 1, wherein the changeable stimulus comprises temperature or voltage, and wherein the control circuit provides a control stimulus to change the temperature or voltage of the controllable material.

7. The attenuation system of claim 6, wherein:

the controllable attenuator includes a controlling element, having an input for receiving the control stimulus from said control circuit, and arranged with respect to the controllable material to change the temperature, or voltage, and therefore the refractive index thereof in accordance with the control stimulus.

8. The attenuation system of claim 1, wherein:

the controllable attenuator includes a bulk material formed over the controllable material into which the extracted optical energy is radiated.

9. The attenuation system of claim 8, wherein:

the controllable material has a controllable index of refraction approximately matching the index of refraction of cladding of the fiber optic; and

the bulk material formed over the controllable material has a fixed index of refraction higher than the effective mode index of refraction of the fiber optic.

10. The attenuation system of claim 1, wherein said control circuit controls the amount of the changeable stimulus applied to the controllable material also in accordance with a desired level stimulus.

11. The attenuation system of claim 1, wherein the level circuit comprises at least one sensor for sensing a level of at least a portion of the optical energy transmitted in the fiber optic, the level circuit providing the feedback stimulus in accordance with said sensed level.

12. A method for forming an attenuation system for attenuating optical energy transmitted through a fiber optic, comprising:

providing a portion of the fiber optic having a side surface thereof through which at least some of the optical energy transmitted therein can be extracted;

forming a controllable material over the surface for controlling an amount of optical energy extracted from the fiber optic in accordance with a changeable stimulus applied thereto which affects the refractive index thereof;

providing a level circuit for providing a feedback stimulus having a value related to at least a portion of the optical energy transmitted in the fiber optic; and

providing a control circuit for controlling an amount of the changeable stimulus applied to the controllable material in accordance with the feedback stimulus.

13. The method of claim 12, wherein the changeable stimulus applied to the controllable material comprises temperature or voltage, and wherein the control circuit is formed to provide a control stimulus to change the temperature or voltage of the controllable material.

14. The method of claim 13, further comprising:

providing a controlling element, having an input for receiving the control stimulus from the control circuit, and arranged with respect to the controllable material to change the temperature, or voltage, and therefore the refractive index thereof in accordance with said control stimulus.

15. The method of claim 12, further comprising:

forming a bulk material over the controllable material into which the extracted optical energy is radiated.

16. The method of claim 15, wherein:

the controllable material is formed to have a controllable index of refraction approximately matching the index of refraction of cladding of the fiber optic; and

the bulk material formed over the controllable material is formed to have a fixed index of refraction higher than the effective mode index of refraction of the fiber optic.

17. The method of claim 12, wherein the level circuit includes:

a first sensing circuit for sensing an amount of optical energy transmitted in said fiber optic prior to any extraction thereof by said controllable attenuator;

a second sensing circuit for sensing an amount of optical energy transmitted in said fiber optic following any extraction thereof by said controllable attenuator; and

a circuit for determining a level of optical energy extracted from said fiber optic according to the sensed amounts of optical energy prior to and following the extraction thereof by said controllable attenuator, and providing the feedback stimulus to the control circuit based on said level of optical energy extracted.

18. The method of claim 17, wherein said providing the control circuit further comprises providing a comparing circuit for comparing the feedback stimulus and a desired level stimulus applied thereto, and, based on any difference therebetween, changing the value of the changeable stimulus.

19. The method of claim 12, wherein said control circuit further controls the amount of the changeable stimulus applied to the controllable material also in accordance with a desired level stimulus.

20. The method of claim 12, wherein the level circuit comprises at least one sensor for sensing a level of at least a portion of the optical energy transmitted in the fiber optic, the level circuit providing the feedback stimulus in accordance with said sensed level.

21. A method for controllably attenuating optical energy transmitted through a fiber optic, a portion of the fiber optic having a side surface through which at least some of the optical energy can be extracted, comprising:

using an attenuator having a controllable material formed over the surface to controllably extract the optical energy in accordance with a changeable stimulus applied to the controllable material which affects the index of refraction thereof;

providing a feedback stimulus having a value related to at least a portion of the optical energy transmitted in the fiber optic; and

controlling an amount of the changeable stimulus applied to the controllable material according to the feedback stimulus.

22. The method of claim 21, wherein the changeable stimulus comprises temperature or voltage.

23. The method of claim 22, wherein said controlling includes:

using a controlling element, arranged with respect to the controllable material to change the temperature, or voltage, and therefore the refractive index thereof.

24. The method of claim 21, wherein said using an attenuator includes:

using a bulk material over the controllable material into which the extracted optical energy is radiated.

25. The method of claim 24, wherein a portion of cladding encasing a core is removed from the portion of the fiber optic, and wherein:

the controllable material has a controllable index of refraction approximately matching the index of refraction of the cladding; and

the bulk material formed over the controllable material has a fixed index of refraction higher than the effective mode index of refraction of the fiber optic.

26. The method of claim 21, wherein said providing a feedback stimulus includes:

sensing an amount of optical energy transmitted in the fiber optic prior to any extraction thereof through the surface;

sensing an amount of optic energy transmitted in said fiber optic following any extraction thereof through the surface; and

determining a level of optical energy extracted from the fiber optic according to the sensed amounts of optic energy prior to and following the extraction thereof through the surface, and providing the feedback stimulus based on said level of optical energy extracted.

27. The method of claim 26, wherein said controlling includes comparing the feedback stimulus and a desired level stimulus, and, based on any difference therebetween, changing the value of the changeable stimulus provided to the attenuator.

28. The method of claim 21, wherein said controlling comprises controlling the amount of the changeable stimulus applied to the controllable material also in accordance with a desired level stimulus.

29. The method of claim 21, wherein said providing a feedback stimulus comprises:

sensing a level of at least a portion of the optical energy transmitted in the fiber optic, and providing the feedback stimulus in accordance with said sensed level.