THIN-FILM OPTICAL DEVICES

• US 3,614,198 A
• Filed: 06/23/1969
• Issued: 10/19/1971
• Est. Priority Date: 06/23/1969
• Status: Expired due to Term

• Current Assignee: Raymond J. Martin, Reinhard Ulrich
• Original Assignee: Raymond J. Martin, Reinhard Ulrich
• Inventors: Martin, Raymond J., Ulrich, Reinhard
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US04/835,484
• Time in Patent Office: 848 Days
• Field of Search: 350/96WG
• US Class Current: 385/129
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02F 1/295 Analog deflection from or in an optical waveguide structure]

Abstract

Thin-film optical devices are disclosed which function within the plane of a thin-film as lenses or prisms. They function in two dimensions, since the thin dimension of the film serves to guide the beam with respect to the third dimension. The devices are formed integrally from the body of the thin-film by variations in its thickness either along the path of the light beam or by such variations both along the path of the beam and transversely thereto, with contours of constant thickness intersecting the light path in an orientation affecting change of the direction of propagation of at least a portion of the light. Lenses of increased thickness are convergent if provided with convex contours or divergent if provided with concave contours; but lenses of decreased thickness with respect to the surrounding film are convergent if provided with concave contours and divergent if provided with convex contours. The prisms change the path of the entire beam. They can also be made to provide total internal reflection within the prism or frustrated internal reflection if disposed sufficiently close to another thin-film optical device. It is advantageous for the efficient operation of these devices if the mentioned changes in the film thickness are not abrupt but rather are tapered smoothly over a distance of several wavelengths of the light. This minimizes reflection losses and conversion to other modes.

Claims

1. An optical device of the type comprising a body of optically transparent material having one dimension comparable to the wavelength of light to be propagated therein, having a transverse dimension of magnitude substantially greater than the width of the beam of said light and having at least one smooth surface defining a limit of said one dimension, said device being characterized in that the bulk index of refraction, n, of said body at the wavelength of said light is constant throughout said body but said one dimension varies in magnitude along the intended path of said light thereby varying the relative phase constant, Beta , of said body throughout the region of variation of said one dimension, said one dimension varying with transverse contours of constant magnitude intersecting at least a portion of siad light obliquely, said device affecting change of direction of propagation of said portion of said light.

2. An optical device of the type claimed in claim 1 in which the one dimension of said body varies in magnitude along the path of propagation of said light with transversely linear contours of constant magnitude intersecting said path obliquely, whereby said path is bent.

3. An optical device of the type claimed in claim 2 in which the one dimension of said body decreases in magnitude along the path of propagation of said light with transversely linear contours of constant magnitude intersecting said path obliquely at an angle greater than the critical angle for reflection of said light.

4. An optical device of the type claimed in claim 1 in which the one dimension of said body varies in magnitude along the direction of propagation of said light with transversely curved contours of constant magnitude intersecting said path, said curved contours affecting change of direction of propagation of the light at the edges of said path with respect to the direction of propagation of the light in the center of said path.

5. An optical devIce of the type claimed in claim 4 in which the one dimension of said body increases in magnitude along the path of propagation of said light with transversely curved contours having centers of curvature located in the forward direction along said ptah to provide convergent focusing of said light.

6. An optical device of the type claimed in claim 4 in which the one dimension of said body decreases in magnitude along the path of propagation of said light with transversely curved contours having centers of curvature located in the backward direction along said path to provide convergent focusing of said light.

7. An optical device of the type claimed in claim 4 in which the one dimension of said body increases in magnitude along the path of propagation of said light with transversely curved contours having centers of curvature located in the backward direction along said path to provide divergent focusing of said light.

8. An optical device of the type claimed in claim 4 in which the one dimension of said body decreases in magnitude along the path of propagation of said light with transversely curved contours having centers of curvature located in the forward direction to provide divergent focusing of said light.

9. An optical device of the type claimed in claim 1 in which the one dimension of said body first increases then decreases in magnitude in a limited area along the path of propagation of said light to provide a limited region of increased relative phase constant, Beta throughout the area of expansion of said one dimension.

10. An optical device of the type claimed in claim 1 in which the one dimension of said body first decreases then increases in magnitude in a limited area along the path of propagation of said light to provide a limited region of decreased relative phase constant, Beta throughout the area of contraction of said one dimension.

11. An optical device of the type claimed in claim 1 in which the one dimension of the body varies not only along the path but also transversely to the path.

12. An optical device of the type claimed in claim 11 in which the one dimension of the body varies monotonically transversely to the path to bend the path.

13. An optical device of the type claimed in claim 11 in which the one dimension of the body varies transversely to the path in a curved symmetrical fashion with respect to the path.

14. An optical device of the type claimed in claim 1 in which the one dimension first decreases along a direction oblique to the path to an extent which would provide reflection of light propagating in said path and then increases along a geometrical extension of said direction to an extent to frustrate said reflection.

15. An optical device of the type claimed in claim 1 in which the one dimension of the body varies smoothly throughout a sufficient plurality of light wavelengths along the path to prevent substantial mode conversion of said light.

16. An optical device of the type claimed in claim 15 in which the one dimension of the body varies throughout a pathlength distance such that the angle formed by the upper surface with respect to the lower surface at no point exceeds about 10* .

17. An optical device of the type claimed in claim 15 in which the one dimension of the body varies throughout a pathlength distance such that the angle formed by the upper surface with respect to the lower surface at no point exceeds about 5*.