Distributed optical structures designed by computed interference between simulated optical signals
An optical apparatus comprises a planar optical waveguide and at least one set of diffractive elements formed in or on the waveguide. The waveguide is arranged to confine propagating optical signals in at least one transverse dimension. The diffractive element set collectively exhibits a positional variation in diffractive amplitude, optical separation, or spatial phase over some portion of the set. The diffractive element set is collectively arranged to route, as an output optical signal, between corresponding input and output optical ports, a corresponding diffracted portion of an input optical signal. The diffractive element set is collectively arranged so that the input optical signal or the output optical signal is successively incident on the diffractive elements. The diffractive elements are arranged according to an interference pattern derived from computed interference between a simulated design input optical signal and a simulated design output optical signal, the interference pattern exhibiting said positional variation.
1. An optical apparatus comprising:
a planar optical waveguide arranged so as to substantially confine in at least one transverse spatial dimension optical signals propagating therein; and
at least one set of diffractive elements formed in or on the planar optical waveguide and collectively arranged in or on the planar optical waveguide so as to exhibit a positional variation in diffractive amplitude, optical separation, or spatial phase over some portion of the set,
wherein:
the diffractive element set is collectively arranged in or on the planar optical waveguide so as to route, as an output optical signal, between corresponding input and output optical ports, a corresponding diffracted portion of an input optical signal that is diffracted by the diffractive element set;
the diffractive element set is collectively arranged in or on the planar optical waveguide so that the input optical signal or the output optical signal is successively incident on the diffractive elements of the set; and
the diffractive elements of the set are arranged in or on the planar optical waveguide according to an interference pattern derived from computed interference between a simulated design input optical signal and a simulated design output optical signal, the interference pattern exhibiting said positional variation.
2. The apparatus of claim 1 wherein the diffractive elements are curvilinear diffractive elements.
3. The apparatus of claim 1 wherein the diffractive element set is collectively arranged in or on the planar optical waveguide (i) so that a spatial wavefront of the input optical signal differs in shape from a spatial wavefront of the output optical signal and (ii) an output optical spectrum comprises an input optical spectrum multiplied by a transfer function collectively applied to the input optical signal by the diffractive element set to produce the output optical signal.
4. The apparatus of claim 1 wherein the planar optical waveguide comprises a slab waveguide, and the diffractive element set is collectively arranged in or on the planar optical waveguide so that the input and output optical ports are spatially separated.
5. The apparatus of claim 4 wherein the input and output optical ports are positioned relative to the diffractive element set so that respective propagation directions of the input and output optical signals are separated by a beam crossing angle greater than about 30°.
6. The apparatus of claim 4 wherein the input and output optical ports are positioned relative to the diffractive element set so that respective propagation directions of the input and output optical signals are separated by a beam crossing angle greater than about 60°.
7. The apparatus of claim 4 wherein the input and output optical ports are positioned relative to the diffractive element set so that respective propagation directions of the input and output optical signals are separated by a beam crossing angle greater than about 150°.
8. The apparatus of claim 7 wherein the diffractive element set is collectively arranged in the planar optical waveguide so as to split the input optical signal into multiple output optical signals.
9. The apparatus of claim 7 wherein the diffractive element set comprises means for splitting the input optical signal into multiple output optical signals.
10. The apparatus of claim 7 further comprising a second set of diffractive elements, wherein the diffractive element sets are collectively arranged in the planar optical waveguide so as to split an input optical signal into multiple output optical signals.
11. The apparatus of claim 7 further comprising a second set of diffractive elements, wherein the diffractive element sets comprise means for splitting an input optical signal into multiple output optical signals.
12. The apparatus of claim 1 wherein diffractive elements are collectively arranged in or on the planar optical waveguide so that a second diffracted portion of the input optical signal is routed between the input optical port and a second output optical port, or so that a diffracted portion of a second input optical signal is routed between a second input optical port and the output optical port.
13. The apparatus of claim 12 further comprising a second diffractive element set collectively arranged in or on the planar optical waveguide so as to route the second diffracted portion of the input optical signal or the diffracted portion of the second input optical signal, wherein:
the diffractive elements of the second diffractive element set are arranged in or on the planar optical waveguide according to an interference pattern derived from computed interference between a simulated design input optical signal and a simulated design output optical signal; and
the diffractive element sets are overlaid in or on the planar optical waveguide.
14. The apparatus of claim 12 wherein:
the diffractive element set is collectively arranged in or on the planar optical waveguide so as to route the second diffracted portion of the input optical signal or the diffracted portion of the second input optical signal; and
the diffractive element set is collectively arranged in or on the planar optical waveguide according to an interference pattern derived from computed interference between the simulated design input optical signal, the simulated design output optical signal, and a second simulated design input optical signal or a second simulated design output optical signal.
15. The apparatus of claim 1 wherein the diffractive element set is collectively arranged in or on the planar optical waveguide according to a phase function of an interferogram of the interference pattern.
16. The apparatus of claim 15 wherein the diffractive element set is collectively arranged in or on the planar optical waveguide according to the phase function of the interferogram and a spatially-invariant intensity function thereof.
17. The apparatus of claim 15 wherein each element of the diffractive element set is arranged in or on the planar optical waveguide with respect to a constant-phase-difference contour of the phase function of the interferogram.
18. The apparatus of claim 17 wherein elements of the diffractive element set comprise a binary refractive index modulation.
19. The apparatus of claim 17 wherein elements of the diffractive element set comprise more than two levels of refractive index modulation.
20. The apparatus of claim 17 wherein elements of the diffractive element set comprise a partially reflective boundary.
21. The apparatus of claim 15 wherein the diffractive element set is collectively arranged in or on the planar optical waveguide according to both the phase function of the interferogram and a spatially-varying intensity function thereof.
22. The apparatus of claim 21 wherein the intensity function is proportional to a magnitude of the simulated design input optical signal, to a magnitude of the simulated design output optical signal, or to a product of the magnitudes of the design input and output optical signals.
23. The apparatus of claim 21 wherein the intensity function is chosen to yield a desired spatial transformation upon routing the diffracted portion of the input optical signal between the input optical port and the output optical port.
24. The apparatus of claim 21 wherein the amplitude function is chosen to yield a desired spectral or temporal transformation upon routing the diffracted portion of the input optical signal between the input optical port and the output optical port.
25. The apparatus of claim 1 wherein each of the simulated design input optical signal and the simulated design output optical signal comprises a continuous-wave optical signal.
26. The apparatus of claim 1 wherein the simulated design input optical signal comprises a substantially transform-limited optical pulse, and the simulated design output optical signal comprises a Fourier transform of a desired spectral transfer function.
27. The apparatus of claim 26 wherein the planar optical waveguide comprises a channel waveguide.
28. The apparatus of claim 1 wherein the simulated design input optical signal emanates from a mechanism coupling an out-of-plane optical signal to the interior of a slab waveguide, and the simulated design output signal converges onto a mechanism coupling in-plane optical signals out of the slab waveguide.
29. An optical apparatus comprising:
a planar optical waveguide arranged so as to substantially confine in at least one transverse spatial dimension optical signals propagating therein; and
diffractive means for routing, as an output optical signal, between corresponding input and output optical ports, a corresponding diffracted portion of an input optical signal that is diffracted by the diffractive element set;
wherein:
the diffractive means comprises at least one set of diffractive elements formed in or on the planar optical waveguide and collectively arranged so as to exhibit a positional variation in diffractive amplitude, optical separation, or spatial phase over some portion of the set,
the diffractive element set is collectively arranged in or on the planar optical waveguide so that the input optical signal or the output optical signal is successively incident on the diffractive elements of the set; and
the diffractive elements of the set are arranged in or on the planar optical waveguide according to an interference pattern derived from computed interference between a simulated design input optical signal and a simulated design output optical signal, the interference pattern exhibiting said positional variation.
30. The apparatus of claim 29 wherein the diffractive elements are curvilinear diffractive elements.
31. The apparatus of claim 29 wherein the diffractive element set is collectively arranged in or on the planar optical waveguide (i) so that a spatial wavefront of the input optical signal differs in shape from a spatial wavefront of the output optical signal and (ii) an output optical spectrum comprises an input optical spectrum multiplied by a transfer function collectively applied to the input optical signal by the diffractive element set to produce the output optical signal.