Diffraction-based optical switch
First Claim
1. A method for controlling a light beam, the method comprising:
- providing a diffraction grating, attached to or part of a piezoelectric substrate, having an initial substrate length and being connected to a controllable voltage source having an initial first voltage difference in a selected direction across the substrate;
directing a beam of light, having at least a selected wavelength λ
, at the grating at a selected incidence angle and receiving a first diffracted light beam component of a selected diffraction order m containing the wavelength λ
at a first light-receiving site;
changing the first voltage difference at the first voltage source by a selected first voltage change amount Δ
V1 and permitting the substrate length to change by a selected first length change amount Δ
L1 in the selected direction, whereby at least one of the following occurs, after the first voltage change;
(1) the first diffracted light beam component is received at a selected second light-receiving site, different from the first site, (2) a second diffracted light beam component of order m, containing a second wavelength λ
′
but not the wavelength λ
, is received at the first site, (3) a third diffracted light beam component of order m′
, with m′
≠
m, containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site, and (4) a fourth diffracted light beam component, having an incidence angle different from the selected incidence angle and containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site;
providing a second controllable voltage source having an initial second voltage difference across the substrate in a second selected direction that is transverse or perpendicular to the first direction; and
changing the second voltage difference at the second voltage source by a selected voltage change amount Δ
V2 that is chosen so that at leas one of the following occurs;
(i) the substrate length changes by a selected second length change amount Δ
L2 in the second direction, and (2) a selected axis of the grating is rotated by a selected angle change amount Δ
φ
in a selected plane of the substrate.
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Accused Products
Abstract
Method and system for controllably redirecting a light beam, having a central wavelength λ, from a first light-receiving site to a second light-receiving site. A diffraction grating is attached to or part of a piezoelectric substrate, which is connected to one or two controllable voltage difference sources. When a substrate voltage difference is changed and the diffraction grating length in each of one or two directions is thereby changed, at least one of the diffraction angle, the diffraction order and the central wavelength is controllably changed. A diffracted light beam component, having a given wavelength, diffraction angle and diffraction order, that is initially received at a first light receiving site (e.g., a detector or optical fiber) is thereby controllably shifted or altered and can be received at a second light receiving site. A polynomially stepped, chirped grating is used in one embodiment. In another embodiment, an incident light beam, having at least one of first and second wavelengths, λ1 and λ2, is received and diffracted at a first diffraction grating to provide a first diffracted beam. The first diffracted beam is received and diffracted at a second diffraction grating to produce a second diffracted beam. The second diffracted beam is received at a light-sensitive transducer, having at least first and second spaced apart light detector elements that are positioned so that, when the incident light beam has wavelength λ1 or λ2 (λ1≠λ2), the second diffracted beam is received at the first element or at the second element, respectively; change in a selected physical parameter at the second grating can also be sensed or measured. A sequence of spaced apart light detector elements can be positioned along a linear or curvilinear segment with equal or unequal spacing.
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Citations
18 Claims
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1. A method for controlling a light beam, the method comprising:
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providing a diffraction grating, attached to or part of a piezoelectric substrate, having an initial substrate length and being connected to a controllable voltage source having an initial first voltage difference in a selected direction across the substrate;
directing a beam of light, having at least a selected wavelength λ
, at the grating at a selected incidence angle and receiving a first diffracted light beam component of a selected diffraction order m containing the wavelength λ
at a first light-receiving site;
changing the first voltage difference at the first voltage source by a selected first voltage change amount Δ
V1 and permitting the substrate length to change by a selected first length change amount Δ
L1 in the selected direction,whereby at least one of the following occurs, after the first voltage change;
(1) the first diffracted light beam component is received at a selected second light-receiving site, different from the first site, (2) a second diffracted light beam component of order m, containing a second wavelength λ
′
but not the wavelength λ
, is received at the first site, (3) a third diffracted light beam component of order m′
, with m′
≠
m, containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site, and (4) a fourth diffracted light beam component, having an incidence angle different from the selected incidence angle and containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site;
providing a second controllable voltage source having an initial second voltage difference across the substrate in a second selected direction that is transverse or perpendicular to the first direction; and
changing the second voltage difference at the second voltage source by a selected voltage change amount Δ
V2 that is chosen so that at leas one of the following occurs;
(i) the substrate length changes by a selected second length change amount Δ
L2 in the second direction, and (2) a selected axis of the grating is rotated by a selected angle change amount Δ
φ
in a selected plane of the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for controlling a light beam, the system comprising:
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a diffraction grating, attached to or part of a piezoelectric substrates having an initial substrate length, where the grating is positioned to receive a beam of light, having at least a selected wavelength λ
, at a light-receiving site of the grating at a selected incidence angle and to provide a first diffracted light beam component of a selected order m containing the wavelength λ
; and
a first controllable voltage source, connected in a selected direction across the substrate and having an initial voltage difference, where the voltage difference is changed by a selected fit voltage change amount Δ
V1 to cause the substrate length to change by a selected first length change amount Δ
L1 in the selected direction,whereby at least one of the following occurs, after the first voltage change;
(1) the first diffracted light beam component is received at a selected second light-receiving site, different from the first site, (2) a second diffracted light beam component of order m, containing a second wavelength λ
′
but not the wavelength λ
, is received at the first site, (3) a third diffracted light beam component of order m′
, with m′
≠
m, containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site, and (4) a fourth diffracted light beam component, having an incidence angle different from the selected incidence angle and containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site;
a second controllable voltage ource having an initial second voltage difference across the substrate in a second selected direction that is transverse or perpendicular to the first direction; and
wherein the second voltage difference at the second voltage source can be changed by a elected voltage change amount Δ
V2 that is chosen so that at least one of the following occurs;
(i) the substrate length changes by a selected second length change amount Δ
L2 in the second direction, and (2) a selected axis of the grating is rotated by a selected angle change amount Δ
φ
in a selected plane of the substrate. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for controlling a light beam, the method comprising:
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providing a diffraction grating, attached to or part of a piezoelectric substrate, having an initial substrate length and being connected to a controllable voltage source having an initial voltage difference in a selected direction across the substrate;
providing the substrate with a selected curved surface, and providing the grating on the curved surface;
directing a beam of light, having at least a selected wavelength λ
, at the grating at a selected incidence angle and receiving a first diffracted light beam component of a selected diffraction order m containing the wavelength λ
at a first light-receiving site; and
changing the voltage difference at the voltage source by a selected voltage change amount Δ
V1 and permitting the substrate length to change by a selected length change amount Δ
L1 in the selected direction,whereby at least one of the following occurs, after the voltage change;
(1) the first diffracted light beam component is received at a selected second light-receiving site, different from the first site, (2) a second diffracted light beam component of order m, containing a second wavelength λ
′
but not the wavelength λ
, is received at the first site, (3) a third diffracted light beam component of order m′
, with m′
≠
m, containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site, and (4) a fourth diffracted light beam component, having an incidence angle different from the selected incidence angle and containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site.
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18. A system for controlling a light beam, the system comprising:
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a diffraction grating, attached to or part of a piezoelectric substrate, having an initial substrate length, where the grating is positioned to receive a beam of light, having at least a selected wavelength λ
, at a light-receiving site of the grating at a selected incidence angle and to provide a first diffracted light beam component of a selected order m containing the wavelength λ
, wherein the substrate is provided with a selected curved surface, and the grating is provided on the curved surface; and
a controllable voltage source, connected in a selected direction across the substrate and having an initial voltage difference, where the voltage difference is changed by a selected voltage change amount Δ
V1 to cause the substrate length to change by a selected length change amount Δ
L1 in the selected direction,whereby at least one of the following occurs, after the voltage change;
(1) the first diffracted light beam component is received at a selected second light-receiving site, different from the first site, (2) a second diffracted light beam component of order m, containing a second wavelength λ
but not the wavelength λ
, is received at the first site, (3) a third diffracted light beam component of order m′
, with m′
≠
m, containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site, and (4) a fourth diffracted light beam component, having an incidence angle different from the selected incidence angle and containing at least one of the first and second wavelengths, is received at at least one of the first site and the second site.
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Specification