An optical multiplexing device includes an optical element having at least one set of diffractive elements, and an optical reflector. The reflector routes, between first and second optical ports, that portion of an optical signal transmitted by the diffractive element set. The diffractive element set routes, between first and multiplexing optical ports, a portion of the optical signal that is diffracted by the diffractive element set. More complex optical multiplexing functionality(ies) may be achieved using additional sets of diffractive elements, in a common optical element (and possibly overlaid) or in separate optical elements with multiple reflectors. Separate multiplexing devices may be assembled with coupled ports for forming more complex devices. The respective portions of an optical signal transmitted by and reflected/diffracted from the diffractive element set typically differ spectrally. The portion reflected from the diffractive element set may comprise one or more channels of an optical WDM system.
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49. An optical apparatus, comprising:
diffractive means for routing, between a first optical port and a multiplexing optical port and according to a diffractive transfer function, a corresponding diffracted portion of an optical signal propagating within an optical element, the diffractive element means having a resonance frequency band fres; and
achromatic reflective means for routing, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of the optical signal transmitted by the diffractive routing means,
wherein the reflective routing means acts as a focusing means, and the first and second optical ports are positioned at respective first and second conjugate image points of the focusing means,
e####
and wherein:
(a) diffractive elements of the diffractive means are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion thereof, said positional variation determining at least in part the diffractive transfer function;
or
(b) (1) diffractive elements of the diffractive means are each spatially arranged relative to a corresijonding corresponding diffractive element virtual contour and each comprise at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the diffractive transfer function between the multiplexing optical port and either the first or the second optical port,
and
(3) the diffractive transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
50. An optical apparatus, comprising:
diffractive means for routing, between a first optical port and a multiplexing optical port and according to a diffractive transfer function, a corresponding diffracted portion of an optical signal propagating within an optical element, the diffractive element means having a resonance frequency band fres; and
achromatic reflective means for routing, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of the optical signal transmitted by the diffractive routing means,
wherein the diffractive routing means acts as a focusing means, and the first and second optical ports are positioned at respective first and second conjugate image points of the focusing means,
e####
and wherein:
(a) diffractive elements of the diffractive means are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion thereof, said positional variation determining at least in part the diffractive transfer function;
or
(b) (1) diffractive elements of the diffractive means are each spatially arranged relative to a corresijonding corresponding diffractive element virtual contour and each comprise at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the diffractive transfer function between the multiplexing optical port and either the first or the second optical port,
and
(3) the diffractive transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
35. An optical apparatus, comprising:
diffractive means for routing, between a first optical port and a multiplexing optical port and according to a diffractive transfer function, a corresponding diffracted portion of an optical signal propagating within an optical element, the diffractive element means having a resonance frequency band fres; and
achromatic reflective means for routing, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of the optical signal transmitted by the diffractive routing means,
wherein the optical element comprises a planar optical waveguide, the planar optical waveguide substantially confining in one transverse dimension the optical signal propagating in two dimensions therein,
e####
and wherein:
(a) diffractive elements of the diffractive means are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion thereof, said positional variation determining at least in part the diffractive transfer function;
or
(b) (1) diffractive elements of the diffractive means are each spatially arranged relative to a corresponding diffractive element virtual contour and each comprise at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the diffractive transfer function between the multiplexing optical port and either the first or the second optical port,
and
(3) the diffractive transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
0. 65. An optical apparatus, comprising:
an optical element having at least one set of diffractive elements; and
an optical reflector having a reflective surface coating and spatially separated from said at least one set of diffractive elements,
wherein:
the optical reflector is configured to route, between a first optical port and a second optical port, at least a first portion of an optical signal that propagates within the optical element;
each diffractive element set is configured to route, between at least a third optical port and either the first or the second optical ports, a second portion of the optical signal that is respectively diffracted by each diffractive element set according to a corresponding set transfer function;
the optical element includes a planar optical waveguide, the planar optical waveguide being configured to substantially to confine in one transverse dimension the optical signal propagating in two dimensions therein; and
(a) the diffractive elements of the at least one set are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the at least one set, said positional variation determining at least in part the set transfer function;
or
(b) (1) each diffractive element is spatially arranged relative to a corresponding diffractive element virtual contour and includes at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of an incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of the incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the corresponding set transfer function between the at least the third optical port and either the first or the second optical ports, and
(3) the corresponding set transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of one or more diffractive element sets, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
21. An optical apparatus, comprising:
an optical element having at least one set of diffractive elements, the at least one set of diffractive elements having a resonance frequency band fres; and
an achromatic optical reflector,
e####
wherein:
the reflector routes, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of an optical signal propagating within the optical element and transmitted by each diffractive element set;
each diffractive element set routes, between a corresponding multiplexing optical port and either the first or the second optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set according to a corresponding set transfer function;
and
the reflector comprises a focusing reflector, and the first and second optical ports are positioned at respective first and second conjugate image points of the focusing reflector,
and wherein:
(a) the diffractive elements of the set are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the set, said positional variation determining at least in part the set transfer function;
or
(b) (1) each diffractive element is spatially arranged relative to a corresponding diffractive element virtual contour and comprises at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the corresponding set transfer function between the corresponding multiplexing optical port and either the first or the second optical port,
and
(3) the corresponding set transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
1. An optical apparatus, comprising:
an optical element having at least one set of diffractive elements, the at least one set of diffractive elements having a resonance frequency band fres; and
an achromatic optical reflector,
e####
wherein:
the reflector routes, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of an optical signal propagating within the optical element and transmitted by each diffractive element set;
each diffractive element set routes, between a corresponding multiplexing optical port and either the first or the second optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set according to a corresponding set transfer function;
and
the optical element comprises a planar optical waveguide, the planar optical waveguide substantially confining in one transverse dimension the optical signal propagating in two dimensions therein,
and wherein:
(a) the diffractive elements of the set are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the set, said positional variation determining at least in part the set transfer function;
or
(b) (1) each diffractive element is spatially arranged relative to a corresponding diffractive element virtual contour and comprises at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the corresponding set transfer function between the corresponding multiplexing optical port and either the first or the second optical port,
and
(3) the corresponding set transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
0. 70. A method of operating an optical apparatus having an optical element, at least one set of diffractive elements, and an optical reflector, the method comprising:
receiving, by the optical element, an optical signal;
routing, by the optical reflector which has a reflective surface coating and which is spatially separated from said at least one set of diffractive elements, between a first optical port and a second optical port, at least a first portion of the optical signal that propagates within the optical element; and
routing, between at least a third optical port and either the first or the second optical ports, a second portion of the optical signal that is respectively diffracted by each diffractive element set according to a corresponding set transfer function,
wherein:
the optical element includes a planar optical waveguide, the planar optical waveguide being configured to substantially to confine in one transverse dimension the optical signal propagating in two dimensions therein; and
(a) the diffractive elements of the at least one set are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the at least one set, said positional variation determining at least in part the set transfer function;
or
(b) (1) each diffractive element is spatially arranged relative to a corresponding diffractive element virtual contour and includes at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of an incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of the incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the corresponding set transfer function between the at least the third optical port and either the first or the second optical ports, and
(3) the corresponding set transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of one or more diffractive element sets, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
23. An optical apparatus, comprising:
an optical element having at least one set of diffractive elements, the at least one set of diffractive elements having a resonance frequency band fres; and
an achromatic optical reflector,
e####
wherein:
the reflector routes, between a first optical port and a second optical port, that portion having frequency bands f1, . . . fres−1, fres+1 . . . fn of an optical signal propagating within the optical element and transmitted by each diffractive element set;
each diffractive element set routes, between a corresponding multiplexing optical port and either the first or the second optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set according to a corresponding set transfer function;
and
the diffractive element set comprises a set of focusing diffractive elements, and the corresponding multiplexing optical port and either the first or the second optical port are positioned at respective first and second conjugate image points of the diffractive elements set,
and wherein:
(a) the diffractive elements of the set are collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the set, said positional variation determining at least in part the set transfer function;
or
(b) (1) each diffractive element is spatially arranged relative to a corresponding diffractive element virtual contour and comprises at least one diffracting region thereof, the diffracting regions having at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom,
(2) each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that each diffractive element set collectively provides the corresponding set transfer function between the corresponding multiplexing optical port and either the first or the second optical port,
and
(3) the corresponding set transfer function or at least one corresponding diffractive element transfer function is determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
2. The apparatus of
the first optical port is an input port;
the second optical port is an output port;
the multiplexing optical port is a dropped-channel port;
the diffractive element set routes the corresponding diffracted portion of the optical signal from the input port to the dropped-channel port; and
the apparatus functions as a channel-dropping multiplexer.
3. The apparatus of
the first optical port is an input port;
the second optical port is an output port;
the multiplexing optical port is an added-channel port;
the diffractive element set routes the corresponding diffracted portion of the optical signal from the added-channel port to the output port; and
the apparatus functions as a channel-adding multiplexer.
4. The apparatus of
the first optical port is an input port;
the second optical port is an output port;
the multiplexing optical port is a dropped-channel port;
the diffractive element set routes a corresponding diffracted portion of the optical signal from the input port to the dropped-channel port;
the diffractive element set routes a corresponding diffracted portion of the optical signal from an added-channel port to the output port; and
the apparatus functions as an add/drop multiplexer.
5. The apparatus of
a first optical waveguide optically coupled to the input port;
a second optical waveguide optically coupled to the output port;
a third optical waveguide optically coupled to the dropped-channel port; and
a fourth optical waveguide optically coupled to the added-channel port,
wherein each of the first, second, third, and fourth optical waveguides substantially confines in two transverse dimensions optical signals propagating therethrough.
7. The apparatus of
8. The apparatus of
9. The apparatus of
a first optical waveguide optically coupled to the first optical port;
a second optical waveguide optically coupled to the second optical port; and
a third optical waveguide optically coupled to the multiplexing optical port,
wherein each of the first, second, and third optical waveguides substantially confines in two transverse dimensions optical signals propagating therethrough.
10. The apparatus of
11. The apparatus of
12. The apparatus of
13. The apparatus of
14. The apparatus of
15. The apparatus of
17. The apparatus of
18. The apparatus of
19. The apparatus of
20. The apparatus of
22. The apparatus of
24. The apparatus of
25. The apparatus of
26. The apparatus of
27. The apparatus of
each diffractive element set routes, between a corresponding one of multiple multiplexing optical ports and either the first or the second optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set; and
the reflector routes, between the first optical port and the second optical port, that portion of the optical signal transmitted by the multiple diffractive element sets.
28. The apparatus of
29. The apparatus of
30. The apparatus of
31. The apparatus of
32. The apparatus of
33. The apparatus of
34. The apparatus of
multiple optical elements, each having a corresponding set of diffractive elements; and
multiple corresponding optical reflectors,
wherein
each reflector routes, between a corresponding first optical port and a corresponding second optical port, that portion of an optical signal transmitted by the corresponding diffractive element set;
each corresponding diffractive element set routes, between the corresponding first optical port and a corresponding multiplexing optical port, a corresponding portion of the optical signal that is diffracted by the corresponding diffractive element set; and
the multiple optical elements are arranged so that at least one optical port of each of the multiple optical elements is coupled to an optical port of another the multiple optical elements.
36. The apparatus of
37. The apparatus of
38. The apparatus of
39. The apparatus of
a first optical waveguide optically coupled to the first optical port;
a second optical waveguide optically coupled to the second optical port;
a third optical waveguide optically coupled to the first multiplexing optical port;
a fourth optical waveguide optically coupled to the second multiplexing optical port,
wherein each of the first, second, third, and fourth optical waveguides substantially confines in two transverse dimensions optical signals propagating therethrough.
41. The apparatus of
a first optical waveguide optically coupled to the first optical port;
a second optical waveguide optically coupled to the second optical port; and
a third optical waveguide optically coupled to the multiplexing optical port,
wherein each of the first, second, and third optical waveguides substantially confines in two transverse dimensions optical signals propagating therethrough.
42. The apparatus of
43. The apparatus of
44. The apparatus of
45. The apparatus of
46. The apparatus of
47. The apparatus of
48. The apparatus of
51. The apparatus of
52. The apparatus of
53. The apparatus of
the reflective routing means routes, between the first optical port and the second optical port, that portion of the optical signal transmitted by the multiple diffractive element sets.
56. The apparatus of
57. The apparatus of
58. The apparatus of
59. The apparatus of
60. The apparatus of
multiple diffractive means for routing, between a corresponding first optical port and a corresponding multiplexing optical port, a corresponding diffracted portion of an optical signal propagating within a corresponding one of multiple optical elements; and
multiple corresponding reflective means for routing, between the corresponding first optical port and a corresponding second optical port, that portion of the optical signal transmitted by the corresponding diffractive element set,
wherein the multiple optical elements are arranged so that the corresponding first and second optical ports are coupled to optical ports of others of the first and second optical ports.
61. The apparatus of
62. The apparatus of
63. The apparatus of
64. The apparatus of
0. 66. The optical apparatus of claim 65 wherein said at least the first portion of the optical signal routed by the optical reflector has been respectively transmitted by each diffractive element set.
0. 67. The optical apparatus of claim 65 wherein the optical reflector includes a focusing reflector, and wherein the first and second optical ports are positioned at respective first and second conjugate image points of the focusing reflector.
0. 68. The optical apparatus of claim 65 wherein the set of diffractive elements includes a set of focusing diffractive elements, and wherein said at least the third optical port and either the first or second optical ports are positioned at respective first and second conjugate image points of the set.
0. 69. The optical apparatus of claim 65 wherein:
the first optical port includes an input port;
the second optical port includes an output port; and
the at least the third port includes an added-channel port or a dropped-channel port.
0. 71. The method of claim 70 wherein said routing, between at least the third optical port and either the first or the second optical ports, is part of a channel-dropping operation.
0. 72. The method of claim 70 wherein said routing, between at least the third optical port and either the first or the second optical ports, is part of a channel-adding operation.
0. 73. The method of claim 70 wherein said at least the first portion of the optical signal routed by the optical reflector has been respectively transmitted by each diffractive element set.
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This application claims benefit of prior-filed co-pending provisional App. No. 60/434,183 entitled “Optical Multiplexing device” filed Dec. 17, 2002 in the names of Dmitri Iazikov, Thomas W. Mossberg, and Christoph M. Greiner, said provisional application being hereby incorporated by reference as if fully set forth herein.
The field of the present invention relates to optical devices incorporating distributed optical structures. In particular, optical multiplexing devices are described herein which include distributed optical structures.
A variety of distributed optical structures (also referred to as holographic optical processors or photonic bandgap structures) are disclosed in:
U.S. non-provisional application Ser. No. 09/811,081 entitled “Holographic spectral filter” filed Mar. 16, 2001 (now U.S. Pat. No. 6,879,441), hereby incorporated by reference as if fully set forth herein;
U.S. non-provisional application Ser. No. 09/843,597 entitled “Optical processor” filed Apr. 26, 2001 (Pub. No. US 2003/0117677 A1: now Pat. No. 6,965,464), hereby incorporated by reference as if fully set forth herein;
U.S. non-provisional application Ser. No. 10/229,444 entitled “Amplitude and phase control in distributed optical structures” filed Aug. 27, 2002 (Pub. No. US 2003/0036444 A1;now U.S. Pat. No. 6,678,429), hereby incorporated by reference as if fully set forth herein;
U.S. non-provisional application Ser. No. 10/653,876 entitled “Amplitude and phase control in distributed optical structures” filed Sep. 02, 2003 (Pub. No. US 2004/0076374 A1; now U.S. Pat. No. 6,829,417), hereby incorporated by reference as if fully set forth herein; and
U.S. provisional application Ser. No. 60/525,815 entitled “Methods and devices for combining of holographic Bragg reflectors in planar waveguides” filed Nov. 28, 2003, hereby incorporated by reference as if fully set forth herein.
Application Ser. No. 09/811,081 (U.S. Pat. No. 6,879,441) discloses that diffractive elements of a diffractive element set can be collectively arranged so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the set. The positional variation can determine at least in part a transfer function imparted on an optical signal routed between optical ports by the diffractive element set.
Application Ser. No. 10/229,444 (U.S. Pat. No. 6,678,429) and application Ser. No. 10/653,876 (U.S. Pat. No. 6,829,417) disclose the following. Each diffractive element of a diffractive element set can be spatially arranged relative to a corresponding diffractive element virtual contour and can comprise at least one diffracting region thereof. The diffracting regions have at least one altered optical property so as to enable diffraction of a portion of the incident optical field therefrom. Each diffractive element diffracts a corresponding diffracted component of an incident optical field with a corresponding diffractive element transfer function so that the diffractive element set collectively provides a set transfer function imparted on an optical signal routed between optical ports by the diffractive element set. The set transfer function or at least one corresponding diffractive element transfer function can be determined at least in part by: (A) a less-than-unity fill factor for the corresponding virtual contour, (B) a non-uniform spatial distribution of multiple diffracting regions along the corresponding virtual contour, (C) variation of a spatial profile of the optical property of at least one diffracting region of the corresponding virtual contour, (D) variation of a spatial profile of the optical property among multiple diffracting regions of the corresponding virtual contour, (E) variation of the spatial profile of the optical property of at least one diffracting region among elements of at least one diffractive element set, (F) longitudinal displacement of at least one diffractive element relative to the corresponding virtual contour, or (G) at least one virtual contour lacking a diffractive element corresponding thereto.
An optical multiplexing device comprises: an optical element having at least one set of diffractive elements; and an optical reflector. The reflector routes, between a first optical port and a second optical port, that portion of an optical signal propagating within the optical element and transmitted by the diffractive element set. The diffractive element set routes, between the first optical port and a corresponding multiplexing optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set. If the first optical port is an input port and the second optical port is an output port, then the apparatus functions as a channel-dropping multiplexer, and the multiplexing optical port is a dropped-channel port. If the first optical port is an output port and the second optical port is an input port, then the apparatus functions as a channel-adding multiplexer, and the multiplexing optical port is an added-channel port. If the diffractive element set routes, between the second optical port and a corresponding second multiplexing optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set, the apparatus functions as an add/drop multiplexer.
The optical element may comprise a planar waveguide, and the diffractive elements may be curvilinear elements. The optical element may allow propagation therein in three dimensions, and the diffractive elements may comprise areal elements. The reflector and/or diffractive element set may comprise focusing element(s), and the optical ports may be located at corresponding conjugate image points. The optical ports may be coupled to optical waveguides, including channel waveguides and/or optical fibers. The reflector may be formed on or in the optical element, or may comprise a separate optical element. The reflector may be substantially achromatic over a design spectral window for the multiplexing device.
More complex optical multiplexing functionality(ies) may be achieved using additional sets of diffractive elements, in a common optical element (and possibly overlaid) or in separate optical elements with multiple reflectors. Separate multiplexing devices may be assembled with coupled ports for forming more complex devices.
The respective portions of an optical signal transmitted by and reflected/diffracted from the diffractive element set typically differ spectrally. The portion reflected from the diffractive element set may comprise at least one channel of an optical WDM system.
Objects and advantages pertaining to optical multiplexing devices may become apparent upon referring to the disclosed embodiments as illustrated in the drawings and disclosed in the following written description and/or claims.
The schematics and embodiments shown in the Figures are exemplary, and should not be construed as limiting the scope of the present disclosure and/or appended claims.
An optical multiplexing device, as disclosed and/or claimed herein, comprises an optical element with one or more sets of diffractive elements. Such a diffractive element set may also be equivalently referred to as a holographic optical processor (HOP) or a photonic bandgap structure, and may be implemented in a variety of ways, including but not limited to those described in the references incorporated hereinabove. The optical multiplexing device further comprises an optical reflector. The reflector routes, between a first optical port and a second optical port, that portion of an optical signal propagating within the optical element and transmitted by the diffractive element set. The first and second optical ports may also be referred to as broadband ports. The diffractive element set routes, between the first optical port and a corresponding multiplexing optical port, a corresponding portion of the optical signal that is diffracted by the diffractive element set. The multiplexing optical port may also be referred to as a narrowband port. The ports may or may not occupy the same physical space.
The optical element may comprise a planar optical waveguide, in which a propagating optical signal is substantially confined in one transverse dimension while propagating in the other two dimensions. Alternatively, the optical element may enable propagation therein in all three spatial dimensions. The optical ports may include or may be coupled to, without limitation, channel waveguides, edge mounted fibers, surface grating couplers, free space propagation, or any other suitable optical means to deliver an optical wave into an optical element and to receive light emerging from the optical element, and may be defined structurally and/or functionally.
An optical element in the form of a planar optical waveguide may comprise at least one core layer between a lower cladding layer and an upper cladding layer, the cladding layers having refractive indices sufficiently different from that of the core layer so as to provide substantial optical confinement in one transverse dimension. The core and cladding layers may be placed on a substrate for mechanical robustness and/or for other technical reasons, but in general a substrate is not required for optical functionality. The scope of the present disclosure and/or appended claims includes variations of this three-layer structure, including without limitation replacement of one or both cladding layers with vacuum, air, or other medium or structure providing substantial optical confinement for optical modes guided by the core layer. The present disclosure and/or appended claims shall also encompass, without limitation, apparatus to change isotropic and/or non-isotropic values of refractive indexes of one or more of the core layer and the cladding layers, using thermo-optical, electro-optical, non-linear optical, stress-optical, or other effects known in the art. Such controlled alteration of refractive index may be applied uniformly or spatially selectively, and may be employed to control wavelength-dependent properties of the diffractive element set, to control polarization-dependent properties of the diffractive element set, to reduce the temperature dependence of the optical properties/performance of the diffractive element set, and/or for other purposes. Control of the wavelength-dependent properties of a diffractive element set (such as shifting its resonance frequency, for example) may be achieved by applying mechanical stress to the optical element to change the spatial separation between the diffractive elements. The core and cladding layers may comprise any optically transmissive media with suitable optical properties, including without limitation silica glass, doped silica glass, other glasses, silicon, III-V semiconductors, other semiconductors, polymers, liquid crystals, combinations thereof, and/or functional equivalents thereof.
A diffractive element set (i.e., holographic optical processor or photonic bandgap structure) may be formed in the optical element (i.e., light transport structure) in all or part of any one or more of the core and cladding layers, by any suitable spatially-selective material processing technique(s), including but not limited to etching, lithography, stamping, molding, UV-exposure, other optical or electromagnetic exposure, electron beam techniques, inscribing, printing, other suitable means for spatially-selective material processing, combinations thereof, and/or functional equivalents thereof. The diffractive elements formed in a planar optical waveguide may typically comprise curvilinear elements, although other suitable configurations may be employed as well. Such curvilinear elements may be linear, arcuate, elliptical, parabolic, hyperbolic, general aspheric, and/or other shapes suitable for routing light between the optical ports. A focusing diffractive element set may be employed with the corresponding optical ports positioned at/near corresponding conjugate image points defined by the diffractive element set.
An optical element allowing propagation of an optical signal in three dimensions may be formed from any suitable optical material, and the diffractive element set may be formed by any suitable technique(s) for spatially-selective material processing (in three dimensions), including those listed hereinabove. The diffractive elements formed in such an element may typically comprise areal elements, although other suitable configurations may be employed as well.
The optical reflector may be integrally formed in and/or on the optical element with the diffractive element set, by any suitable technique(s) and in any suitable configuration. The optical reflector may comprise an additional set of diffractive elements formed in/on the optical element (equivalently, an additional holographic optical processor or photonic bandgap structure), and may be formed in any suitable manner, including those set forth hereinabove. The optical reflector may instead comprise a surface of the optical element, suitably shaped and (if needed or desired) with a suitable optical coating thereon. Such a reflective surface may be formed by any suitable technique(s), including but not limited to cutting, etching, lithography, dicing, scribing, molding, stamping, polishing, or otherwise shaping part of the surface of the optical element to the desired shape. Any suitable reflective coating may be applied to the shaped surface, suitable coatings including but not limited to gold, other metallic coatings, single-layer or multi-layer dielectric coatings, and other suitable reflective coatings. In some circumstances internal reflection at the surface may be relied on (total or otherwise) without a reflective coating. The optical reflector may instead be provided as an optical component separate from the optical element. It is within the scope of the present disclosure and/or appended claims to form the optical reflector using any suitable elements, components, and/or techniques, including without limitation those set forth hereinabove, combinations thereof, and/or functional equivalents thereof. It may be desirable under typical circumstance for the reflectivity of the optical reflector to be substantially wavelength independent over a designed spectral window for the optical multiplexing device, although the reflectivity may have any desired wavelength dependence while remaining within the scope of the present disclosure and/or appended claims. Shapes that may be employed for forming the reflective surface may include without limitation linear, arcuate, elliptical, parabolic, hyperbolic, general aspheric, and/or other shapes suitable for routing light between the first and second optical ports. A focusing optical reflector may be employed with the corresponding optical ports positioned at/near corresponding conjugate image points defined by the optical reflector.
Hereinafter follow a description of general schematics of the optical multiplexing device and then descriptions of specific embodiments of optical multiplexing devices. Designations of frequency bands used hereinafter are for illustration only and shall not be construed as limiting the scope of the disclosure and/or appended claims.
A schematic functional diagram of the basic multiplexing device when the light is injected into the input broadband port is presented in
In the descriptions of
It is to be understood that
The cross-section view in
HOP (6) in the exemplary embodiment of
The reflecting surface (7) in the exemplary embodiment is a circular arc with radius R and a center of curvature (8) substantially coinciding with the midpoint between the coupling apertures of the input (1) and output (2) waveguides. If insertion loss optimization is desired, the reflecting surface (7) may have such width and location to intersect all or most of the light radiated from the coupling aperture of waveguide (1), and waveguide (2) may be positioned at such an angle to maximize the coupling between the waveguides and the light reflected from the reflective surface (which may be evaluated by operating port (2) as an input port).
Input ports may be configured so that light enters the optical element at various angles. Output ports may be configured to optimally couple to light exiting the optical element at various angles. Insertion loss may be minimized by orienting ports so that the output beam wavefront most optimally matches an optical mode supported by the corresponding output means (e.g., output waveguide). Dissimilarly sized input and output coupling apertures may be accommodated by appropriate adjustment of imaging conjugate ratio and hence imaging magnification.
One possible set of beam paths for a dropped optical channel is shown in
In the exemplary embodiments HOP's are used as spectral filters and focusing and/or routing elements, while surface reflectors (mirrors) or broadband HOP's may be used as substantially achromatic focusing and/or routing elements. Combination of one or more frequency-selective HOP's and one or more achromatic reflectors (HOP's and/or mirrors), using one or more optical elements, may produce an OADM device of arbitrary complexity and with an arbitrary number of waveguides and/or add/drop frequency bands. Waveguide apertures (i.e., optical ports) may be placed at arbitrary locations of the optical element(s). While so-called relay-imaging may be employed for routing an optical signal among multiple reflectors and/or diffractive element sets, it need not always be the case that each reflector or diffractive element set bring the optical signal to an image or focus within the optical element. Given the occasional appearance of point defects within an optical element, in some instances it may be desirable to avoid such imaging or focusing of the optical signal. In embodiments resembling the schematic exemplary embodiment of
In the exemplary embodiment of
The functionality of HOP (26) is substantially similar to that of HOP (6) in
In some cases, it may be convenient to use one narrow or multi-band HOP for the add signal and another narrow or multi-band HOP for the drop signal. Modification of the embodiment of
As already stated, the two narrow or multi-band HOP's of
Tunability of the HOP's employed in the multiplexer devices described herein may add useful functionality to the device. Another modification of the embodiment of
Tunability may also be achieved by other means such as application of mechanical stress and controlled changes in HOP temperature. These and other means known in the art to produce controlled changes in optical path length within the HOP structure may be employed to create tunable OADM devices within the scope of the present disclosure and/or appended claims.
It is intended that equivalents of the disclosed exemplary embodiments and methods shall fall within the scope of the present disclosure and/or appended claims. It is intended that the disclosed exemplary embodiments and methods, and equivalents thereof, may be modified while remaining within the scope of the present disclosure and/or appended claims.
Mossberg, Thomas W., Greiner, Christoph M., Iazikov, Dmitri
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