Monolithic, three-dimensional infrared waveguide for high power lasers

• US 4,124,270 A
• Filed: 03/30/1977
• Issued: 11/07/1978
• Est. Priority Date: 03/30/1977
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Cheo, Peter K.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Levy, Stewart
• Application Number:
  US05/782,857
• Time in Patent Office: 587 Days
• Field of Search: 350/96 WG, 350/96 C, 350/96.11, 350/96.12, 350/96.15, 331/94.5 H
• US Class Current: 385/130
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02F 1/035 in an optical waveguide structure
• CPC Class Codes: G02F 1/125 in an optical waveguide structure

Abstract

A plurality of different configuration, monolithic, three-dimensional thin-film infrared waveguide structures having high optical power handling capability, low optical propagating loss, long propagation and interaction length and distortion-free characteristics are disclosed, each having characteristics for use in electrooptic and acousto-optic applications.

Claims

1. A thin-film optical waveguide for providing guided mode propagation of an infrared laser, comprising:

a monolithic, solid material planar structure of determined length and width having two mutually opposed, parallel major surfaces, and including a guided laser propagation path extending along a central portion of the longitudinal axis of the structure between said major surfaces, said monolithic structure having a material thickness in the region of the guided propagation path which is dependent on the wavelength of the infrared laser;

optical couplers, one each disposed at opposite ends of a first one of said major surfaces for optically coupling the laser beam through said guided laser propagation path; and

a metallic base, disposed on a second one of said major surfaces for providing dissipation of the laser signal power within said structure.

2. The waveguide according to claim 1, wherein said monolithic structure material thickness in the region of said guided propagation path is uniform to within one micron per square centimeter.

3. The waveguide according to claim 1, wherein said monolithic material comprises a low loss, laser transmitting medium having an index of refraction greater than unity.

4. The waveguide according to claim 1, wherein the material thickness between said major surfaces is from two to three times the wavelength of the laser propagating through said guided propagation path.

5. The waveguide according to claim 1, wherein said metallic base is bonded to the second one of said major surfaces with a thin film of low viscosity resin.

6. A waveguide according to claim 1, wherein said monolithic material structure further includes parallel channels formed along the length of, and along the outside width of, a central region of said first major surface, said channels providing in combination a ridge portion extending along the longitudinal axis of said monolithic structure in the central region of said first major surface, said ridge portion including said guided propagation path, said ridge portion having a width in dependence on a minimum diameter of a focused infrared laser beam.

7. A thin-film optical waveguide for providing guided mode propagation of an infrared laser, comprising:

a bi-level monolithic structure of a low loss, laser transmitting material having an index of refraction greater than unity, said bi-level structure including a lower platform portion having a determined length and width and having first and second mutually opposed, parallel major surfaces, said structure further including a raised portion projecting from a central region of said first major surface, said raised portion including a guided laser propagation path extending along the longitudinal axis thereof, said raised portion having a principal surface parallel to said first and second major surfaces and spaced from said second major surface at a first dimension defining a uniform material thickness selected dependence on the wavelength of the laser signal, said lower platform portion having a uniform material thickness between said first and second major surfaces which has an absolute value in dependence on a selected one of a plurality of guided laser propagation modes within said guided propagation path and which is less than said first dimension, said raised portion having a smooth taper at each end of its longitudinal axis to provide a piece-wise linear transition in thickness between said raised portion of said platform portion;

optical couplers, disposed at each end of said first major surface of said lower platform portion, for providing optical coupling of the laser through said guided laser propagation path; and

a metallic base, bonded to said second major surfaces for providing dissipation of the laser signal power from said monolithic structure.

8. The waveguide according to claim 7, wherein said raised portion and said platform portion each have a thickness uniformity on the order of one micron per square centimeter.

9. The waveguide according to claim 8, wherein said raised portion is in the form of a raised ridge extending along the longitudinal axis of said first major surface, and having a determined width in dependence on a minimum diameter of a focused infrared laser beam.

10. The waveguide according to claim 8, wherein said first dimension is selected at a value in the range of from two to three times the wavelength of the laser propagating through said guided propagation path.

11. A thin-film optical waveguide for providing guided mode propagation of an infrared laser, comprising:

a monolithic structure of a low-loss, laser transmitting material having an index of refraction greater than unity, said monolithic structure having a determined length and width and having two mutually opposed, parallel major surfaces, said structure having a uniform material thickness between said parallel major surfaces having an absolute value in dependence on the wavelength of the laser, said structure further including parallel channels formed along the length of, and along the outside width of, a central region of a first one of said major surfaces, said channels providing in combination a ridge portion extending along the longitudinal axis of said structure in the central portion of said first major surface occupied by said channels, said ridge portion including said guided propagation path and having a width in dependence on a minumum diameter of a focused laser beam;

optical couplers, disposed at each end of said first major surface, for providing optical coupling of the laser beam through said guided laser propagation path within said ridge portion; and

a metallic base, bonded to the second one of said major surfaces, for providing dissipation of the laser signal power within from the waveguide.

12. The waveguide according to claim 11, wherein said structure material thickness between said two major surfaces is uniform to within one micron per square centimeter.

13. A thin-film optical waveguide for providing guided mode propagation of an infrared laser, comprising:

a monolithic, solid material structure of general rectangular shape having a structure length and width dimension which defines two mutually opposed, parallel major surfaces extending along the longitudinal axis thereof, including a first major surface having a planar contour, and a second major surface having a bi-level contour defined by a principal surface and first and second minor surfaces each at a width dimension equal to that of said structure, said principal surface extending along the central portion of the length of said second major surface and spaced at a first dimension from said first major surface, said first and second minor surfaces extending, one each, along opposite end portions of said second major surface, each spaced from said first major surface at a second dimension less than said first dimension and each connected to said principal surface through a smooth, piece-wise linear taper, the solid material in the region of said structure bounded by said principal surface and the portion of said first major surface parallel therewith defining a guided laser propagation path with a material thickness defined by said first dimension in dependence on the wavelengths of the guided laser, the solid material at each end of said monolithic structure bounded by said first and second minor surfaces and the portion of said first major surface parallel therewith defining optical coupling regions with a material thickness defined by said second dimension;

optical coupling means, disposed, one each, in each of said optical coupling regions for optically coupling the laser through said guided laser propagation path; and

heat sink means, disposed on said first major surface for providing dissipation of the laser signal power from said monolithic structure.

14. The waveguide according to claim 13, wherein said first dimension is established at a value in the range of from two to three times the value of the wavelength of the laser coupled through said guided propagation path.

15. The waveguide according to claim 14, wherein said first dimension spacing of said principal surface from said first major surface is uniform along the entire surface area of said principal surface to within one micron per square centimeter.

16. The waveguide according to claim 14, wherein said solid material comprises a low loss, laser transmitting medium having an index or refraction greater than unity.

17. The waveguide according to claim 14, wherein said solid material is a crystal material selected from the group consisting of Gallium Arsenide (GaAs), Cadmium Teluride (CdTe), and Zinc Selenide (ZnSe).

18. The waveguide according to claim 14, wherein said principal surface has a width dimension less than that of said structure width to provide a raised ridge extending along the central portion of the length of said second major surface, said principal surface width being selected in dependence on the beam diameter of the laser coupled through said guided propagation path, said second major surface being spaced from said first major surface at said second dimension along all points of the surface area thereof except that central portion occupied by said principal surface along said raised ridge.