Multi-channel optical filter

• US 7,184,215 B2
• Filed: 06/22/2004
• Issued: 02/27/2007
• Est. Priority Date: 01/26/2001
• Status: Expired due to Fees

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Pelekhaty, Vladimir
• Primary Examiner(s): Dunn; Drew A.
• Assistant Examiner(s): PRITCHETT, JOSHUA L
• Application Number:
  US10/873,770
• Publication Number:
  US 20050024728A1
• Time in Patent Office: 980 Days
• Field of Search: 359124-131, 359/577, 359/580, 359586-590, 385/37
• US Class Current: 359/588
• CPC Class Codes: G02B 5/288 comprising at least one thin film resonant cavity, e.g. in bandpass filters
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements

Abstract

An exemplary embodiment of the invention is an optical filter including a mirror including a plurality of first dielectric layers having a first index of refraction and a plurality of second dielectric layers having a second index of refraction. A plurality of the first dielectric layers have an integer quarter wave optical thickness and at least one of the first dielectric layers has a non-integer quarter wave optical thickness. A plurality of the second dielectric layers have an integer quarter wave optical thickness and at least one of the second dielectric layers has a non-integer quarter wave optical thickness. In an exemplary embodiment, the non-integer quarter wave optical thickness first layer and the non-integer quarter wave optical thickness second layer are determined so as to enhance transmission at a predetermined wavelength.

Claims

1. An optical filter comprising:

a mirror formed from q number of layers comprising a plurality of first dielectric layers having a first index of refraction, a plurality of second dielectric layers having a second index of refraction, and a composite layer having a third index of refraction that is between the first index of refraction and the second index of refraction, formed at a third layer and a q-2 layer, wherein said composite layer is formed by a high refractive index material being clad with two separate low refractive index materials;

wherein a plurality of said first dielectric layers have an integer quarter wave optical thickness and at least one of said first dielectric layers has a non-integer quarter wave optical thickness,

wherein a plurality of said second dielectric layers have an integer quarter wave optical thickness and at least one of said second dielectric layers has a non-integer quarter wave optical thickness, and

wherein the layers are arranged at least with layer 1 and layer q being first dielectric layers having a high index of refraction, layer 2 and layer q-1 being second dielectric layers having a low index of refraction, layer 3 and layer q-2 being third dielectric layers having an intermediate index of refraction, layer 4 and layer q-3 being second dielectric layers having the low index of refraction, and layer 5 and layer q-4 being first dielectric layers having the high index of refraction.

2. The optical filter of claim 1 wherein said first dielectric layer having a non-integer quarter wave optical thickness has a physical thickness different than a physical thickness of said first dielectric layers having an integer quarter wave optical thickness.

3. The optical filter of claim 1 wherein said second dielectric layer having a non-integer quarter wave optical thickness has a physical thickness different than a physical thickness of said second dielectric layers having an integer quarter wave optical thickness.

4. The optical filter of claim 1 further comprising:

a second mirror including a plurality of first dielectric layers having said first index of refraction and a plurality of second dielectric layers having said second index of refraction; and

a spacer positioned between said mirror and said second mirror.

5. The optical filter of claim 1 wherein said optical thickness of said first dielectric layer having a non-integer quarter wave optical thickness is selected to enhance transmission of a predetermined wavelength.

6. The optical filter of claim 5 wherein said optical thickness of said first dielectric layer having a non-integer quarter wave optical thickness is selected to maintain a predefined reflectivity for said mirror.

7. The optical filter of claim 5 wherein said predetermined wavelength corresponds to a service channel in an optical communications system.

8. The optical filter of claim 1 wherein said optical thickness of said second dielectric layer having a non-integer quarter wave optical thickness is selected to enhance transmission of a predetermined wavelength.

9. The optical filter of claim 8 wherein said optical thickness of said second dielectric layer having a non-integer quarter wave optical thickness is selected to maintain a predefined reflectivity for said mirror.

10. The optical filter of claim 8 wherein said predetermined wavelength corresponds to a service channel in an optical communications system.