Optical systems with thin film polarization rotators and method for fabricating such rotators

• US 4,886,332 A
• Filed: 10/19/1987
• Issued: 12/12/1989
• Est. Priority Date: 10/19/1987
• Status: Expired due to Term

• Current Assignee: AT&T IPM Corp. (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Wolfe, Raymond
• Primary Examiner(s): Lee, John D.
• Application Number:
  US07/109,989
• Time in Patent Office: 785 Days
• Field of Search: 350/96.12, 350/96.13, 350/96.14, 350/96.15, 350/96.16, 350/96.29, 350/96.34, 350/400, 350/403, 350/405
• US Class Current: 385/11
• CPC Class Codes: G02B 6/126 using polarisation effects G02B6/1226 takes precedence
• CPC Class Codes: G02F 1/0955 used as non-reciprocal devices, e.g. optical isolators, circulators
• CPC Class Codes: G11B 7/135 Means for guiding the beam from the source to the record carrier or from the record carrier to the detector

Abstract

A method for fabricating a polarization rotator which includes a thin film waveguide exhibiting essentially zero linear birefringence in the absence of an externally applied stress, as well as an optical system incorporating said rotator, is disclosed.

Claims

1. An optical system, comprising:

a source of electromagnetic radiation;

a component of said system, capable of optical communication with said source, serving to transmit or reflect at least a portion of the electromagnetic radiation emitted by said source; and

a polarization rotator including a thin film optical waveguide, capable of optical communication with said source and said component, characterized in that

said thin film waveguide exhibits essentially zero linear birefringence in the absence of an extremely applied stress in relation to at least one wavelength of incident, linearly polarized light of any polarization orientation.

2. The optical system of claim 1 wherein said optical system includes an optical isolator, said isolator including said polarization rotator.

3. The optical system of claim 1 wherein said optical system includes an optical circulator, said circulator including said polarization rotator.

4. The optical system of claim 1 wherein said optical system includes an optical switch, said switch including said polarization rotator.

5. The optical system of claim 1 wherein said thin film optica;

waveguide includes material having a composition which includes iron and oxygen.

6. The optical system of claim 5 wherein said composition further includes yttrium.

7. The optical system of claim 5 wherein said composition further includes a rear earth element.

8. The optical system of claim 5 wherein said composition further includes bismuth.

9. An optical system, comprising:

a source of electromagnetic radiation; and

a thin film waveguide capable of optical communication with said source, characterized in that

said thin film waveguide exhibits essentially zero linear birefringence in the absence of an externally applied stress in relation to at least one wavelength of incident, linearly polarized light of any polarization orientation.

10. The optical system of claim 9, further comprising a detector of electromagnetic radiation, capable of optical communication with said waveguide.

11. A method for fabricating a device, comprising the steps of:

forming a thin film waveguide on a substrate, said waveguide exhibiting at least first and second components of linear birefringence, said first component being shape linear birefringence and said second component being of opposite sign to said first component, characterized in that

said forming step includes the step of altering said first component until the algebraic sum of said at least first and second components in relation to at least one wavelength of light is essentially zero in the absence of an externally applied stress.

12. The method of claim 11 wherein said second component of linear birefringence includes stress-induced linear birefringence.

13. The method of claim 11 wherein said second component of linear birefringence includes growth-induced linear birefringence.