Photonic crystal structure for mode conversion

• US 20050152656A1
• Filed: 11/21/2002
• Published: 07/14/2005
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique
• Original Assignee: Centre National De La Recherche Scientifique
• Inventors: Lalanne, Philippe, Talneau, Ann Juilette
• Granted Patent: US 7,242,837 B2
• Time in Patent Office: Days
• US Class Current: 385/129
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/14 Mode converters

Abstract

A photonic crystal guided propagation structure. The structure includes a guide portion Wn, n being a positive real number or zero number, having a first configuration of rows of patterns, and a guide portion Wm, m being a real number, m>n, having a second configuration of rows of patterns, and a transition zone of distance D located between guide portion Wn and guide portion Wm, in which patterns aligned with at least one row of patterns in the first configuration decrease in size over distance D to allow progressive passing from the first configuration of rows of patterns to the second configuration of rows of patterns. The structures can be applied to the area of integrated optics (semiconductor lasers, laser modulators, filters, multiplexors, etc.).

Claims

1-23. -23. (canceled)

24. A photonic crystal guided propagation structure comprising:

a guide portion Wn, n being a positive real number or zero number, having a first configuration of rows of patterns;

a guide portion Wm, m being a real number, m>

n, having a second configuration of rows of patterns; and

a transition zone of a predetermined distance located between guide portion Wn and guide portion Wm, in which patterns aligned with at least one row of patterns in the first configuration of rows of patterns decrease in size over the predetermined distance to allow progressive passing from the first configuration of rows of patterns to the second configuration of rows of patterns.

25. A guided propagation structure according to claim 24, wherein the patterns define a periodic network.

26. A guided propagation structure according to claim 25, wherein the periodic network is a triangular lattice whose mesh size is substantially 450 nm.

27. A guided propagation structure according to claim 24, wherein the patterns are holes.

28. A guided propagation structure according to claim 27, wherein the holes have a diameter of substantially 300 nm in the first and second guide portions.

29. A guided propagation structure according to claim 28, wherein a number of holes of the transition zone, which are aligned with a row of holes in the first guide portion and which decrease in size, is equal to two, said two holes having respective diameters of 200 nm and 100 nm.

30. A guided propagation structure according to claim 28, wherein a length of the predetermined distance is substantially 700 nm.

31. A guided propagation structure according to claim 27, wherein the holes positioned in the transition zone are increasingly less deep to pass from the first guide portion zone to the second guide portion.

32. A guided propagation structure according to claim 24, wherein the patterns are pieces in material with an index, added to holes formed in the photonic crystal.

33. A guided propagation structure according to claim 24, wherein the patterns are pillars.

34. A guided propagation structure according to claim 33, wherein the pillars are of square or rectangular section.

35. A transition between a strip guide and a photonic crystal guide, comprising a guided propagation structure according to claim 24.

36. A transition according to claim 35, wherein the guided propagation structure is a structure in which n=1 and m=3.

37. A guided propagation structure comprising:

a first waveguide;

a second waveguide; and

a mode converter between the first and second waveguides, wherein the mode converter is a guided propagation structure according to claim 24.

38. A structure according to claim 37, wherein the first waveguide is a photonic crystal guided propagation structure.

39. A structure according to claim 37, wherein the first waveguide is a strip guide.

40. A structure according to claim 37, wherein the second waveguide is a photonic crystal guided propagation structure.

41. A structure according to claim 37, wherein the second waveguide is a strip guide.

42. A structure according to claim 37, wherein the first waveguide is a photonic crystal guide and the second waveguide is a photonic crystal guide comprising a set of patterns forming a mirror.

43. A photonic crystal cavity, successively comprising:

a first guide portion having a first configuration of rows of patterns;

a second guide portion forming a mirror and having a second configuration of rows of patterns;

a third guide portion having a third configuration of rows of patterns;

a fourth guide portion forming a mirror and having a fourth configuration of rows of patterns identical to the second configuration;

a fifth guide portion having a fifth configuration of rows of patterns; and

a succession of transition zones, a transition zone being positioned between two successive guide portions so that an assembly formed by a transition zone and the two guide portions surrounding the transition zone form a photonic crystal guided propagation structure according to claim 24.

44. A photonic crystal cavity according to claim 43, in which i=k.

45. A photonic crystal cavity according to claim 44, in which i=1 and j=1.

46. A photonic crystal cavity according to claim 44, wherein i=1 and j=3.