Optical grating configured to emit optical beam having predetermined cross-section and predetermined intensity pattern over such cross-section

Abstract

To provide an optical grating which can be configured to emit an optical beam, from optical grating portions of the optical grating, with a predetermined cross-section and / or a predetermined intensity in a portion of the cross-section including light.SOLUTION: An optical grating 100 in a plane defined by a first (X) axis and a second (Y) axis orthogonal to the first axis, is configured to receive a collimated optical signal that propagates parallel to the first axis in an optical grating input 105 of the optical grating, and further configured to radiate an optical beam from an opening of the optical grating. The optical grating comprises N optical waveguides each including a waveguide input, a waveguide end and an optical grating portion that includes the grating input and the grating end, N being an integer greater than 1, the opening being defined by the optical grating portion, each optical waveguide being in the plane and parallel to each of other optical waveguides of the N optical waveguides.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under Contract No. N00014-22-C-1043 awarded by the Office of Naval Research. The government has certain rights in this invention. [Background technology]

[0002] Conventional optical gratings have a non-optimal cross-section, e.g., rectangular, emanating from the optical grating, producing an optical beam with an optical intensity across that cross-section. The performance of systems utilizing one or more optical beams, such as atomic sensors and atomic clocks, can be improved by adjusting the cross-section of the optical beam and the optical intensity of the light present in that cross-section. Summary of the Invention

[0003] In some aspects, the techniques described herein include a method for providing an optical grating in a plane defined by a first axis and a second axis orthogonal to the first axis, the optical grating being configured to receive a collimated optical signal propagating parallel to the first axis at an optical grating input of the optical grating and further configured to emit an optical beam from an aperture of the optical grating, the optical grating including N optical waveguides each including a waveguide input, a waveguide end, and an optical grating portion including the grating input and the grating end, where N is an integer greater than 1, the apertures are defined by the optical grating portions, each optical waveguide is in the plane and is parallel to each of the other optical waveguides of the N optical waveguides, and (a)(i) the N and (a) each grating input of two or more of the optical waveguides is positioned at a different position along or parallel to the first axis, and (b) the grating amplitude differs between at least two optical grating sections in at least one position along or parallel to the second axis, wherein each optical waveguide whose optical grating section begins after the waveguide input along or parallel to the first axis does not have an optical grating and further includes an input optical waveguide section optically connecting the waveguide input to the grating input.

[0004] In some aspects, techniques described herein include a method for emitting an optical beam from an optical grating, the method including: receiving a collimated optical signal at an optical grating input of the optical grating, the collimated optical signal propagating parallel to a first axis; and emitting the optical beam from an aperture of the optical grating, the optical grating including N optical waveguides that are in a plane defined by the first axis and a second axis orthogonal to the first axis, each optical waveguide including a waveguide input, a waveguide end, and an optical grating section that includes the grating input and the grating end, where N is an integer greater than 1, the apertures are defined by the optical grating sections, each optical waveguide is in a plane and is parallel to each other optical waveguide of the N optical waveguides, and (a)(i and (ii) each grating end of at least two of the N optical waveguides is located at a different location along or parallel to the first axis; and (b) the grating amplitude varies between at least two optical grating sections in at least one location along or parallel to the second axis, wherein each optical waveguide whose optical grating section begins after a waveguide input along or parallel to the first axis does not have an optical grating and further includes an input optical waveguide section optically connecting the waveguide input to the grating input.

[0005] In some aspects, the techniques described herein include a method for fabricating a multi-axis optical grating including: (a) an optical grating in a plane defined by a first axis and a second axis orthogonal to the first axis; (b) a multi-axis optical grating configured to receive a collimated optical signal propagating parallel to the first axis at an optical grating input of the optical grating; and (c) a multi-axis optical grating further configured to emit an optical beam from an optical grating portion of the optical grating; (d) the optical grating including N optical waveguides, each including a waveguide input, a waveguide end, and an optical grating portion including the grating input and the grating end, where N is an integer greater than 1, and each optical waveguide is in the plane and parallel to each other optical waveguide of the N optical waveguides; and (e) a multi-axis optical grating including N optical waveguides, each including a waveguide input, a waveguide end, and an optical grating portion including the grating input and the grating end. and (b) each grating end of at least two of the N optical waveguides is located at a different position along or parallel to the first axis, and the grating amplitude differs between at least two optical grating sections in at least one position along or parallel to the second axis, wherein each optical waveguide whose optical grating section begins after a waveguide input along or parallel to the first axis does not have an optical grating and further includes an input optical waveguide section optically connecting the waveguide input to the grating input. [Brief explanation of the drawings]

[0006] Example embodiments will be described with additional specificity and detail using the accompanying drawings, with the understanding that the drawings depict example embodiments only and therefore should not be considered limiting in scope. [Figure 1A] 1 illustrates a plan view of an exemplary optical grating configured to emit an optical beam having a predetermined cross-sectional shape and / or a predetermined optical intensity across a cross-section in which the light resides. [Figure 1B] 1 illustrates a cross-sectional view of an exemplary optical grating according to an embodiment of the present invention, emitting an optical beam having a predetermined cross-sectional shape and an optical intensity where light resides within the cross-sectional shape. [Figure 1C]1 illustrates an exemplary cross-sectional view of an optical beam emitted by an optical grating. [Figure 2A] 1 illustrates a plan view of an optical waveguide of an optical grating. [Figure 2B] 10 illustrates a cross-sectional view of one embodiment of an optional input optical waveguide portion. [Figure 2C] 1 illustrates a cross-sectional view of one embodiment of an optical grating portion. [Figure 2D] 1 illustrates another cross-sectional view of an embodiment of an optical grating. [Figure 3] 1 illustrates a flow diagram of one embodiment of a method for emitting an optical beam from an optical grating fabricated in accordance with an embodiment of the present invention.

[0007] According to common practice, the various illustrated features are not drawn to scale but rather to emphasize specific features relevant to the exemplary embodiments. Reference characters denote like elements throughout the figures and text. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which specific illustrative embodiments are shown by way of illustration. However, it is to be understood that other embodiments may be utilized and structural, mechanical, and / or electrical changes may be made. Furthermore, the methods presented in the drawings and specification should not be construed as limiting the order in which the individual steps may be performed. The following detailed description is not to be construed in a limiting sense.

[0009] An embodiment of the present invention is an optical grating capable of emitting an optical beam having a predetermined cross-section and / or a predetermined optical intensity across a portion of the cross-section containing light. The optical grating lies in a plane defined by a first (X) axis and a second (Y) axis, the first axis and the second axis being orthogonal. The material medium comprising the waveguide extends in the (Z) direction. The optical beam is created from a collimated optical signal received by the optical grating input of the optical grating. The optical beam is emitted from the surface of the optical grating. The cross-section of the optical beam may include one or more closed regions containing light, such as a circle, an ellipse, two parallel lines of light, a letter, a number, etc.

[0010] To achieve a predetermined cross-section of the emitted optical beam, an embodiment of the present invention includes an optical grating with an aperture having a predetermined periphery shape. The optical grating includes N optical waveguides arranged parallel to one another, where N is an integer greater than 1. The N optical waveguides include a first optical waveguide through an Nth optical waveguide. Each optical waveguide includes an optical grating portion including a subwavelength periodic structure formed on the optical waveguide. The aperture is defined by the optical grating portion of the optical grating.

[0011] In embodiments of the present invention, the predetermined optical intensity over the portion of the cross section containing the light may also be varied, and such variation in optical intensity may be achieved by varying the grating amplitude of the optical grating along or parallel to both the first and second axes.

[0012] Optionally, the grating amplitude differs between at least two optical grating portions at at least one location along or parallel to the second axis. Optionally, as illustrated in FIG. (a) the optical grating input 105 (i.e., each optical waveguide input) of the optical grating 100 is positioned along the X-axis at Xin; (b) the optical grating inputs of each of the three optical waveguides 103-4, 103-5, and 103-6 are positioned along the X-axis at Xi1; (c) the optical grating inputs of each of the two optical waveguides 103-2 and 103-7 are positioned along the X axis at Xi2; (d) the optical grating input of each of the two optical waveguides 103-1, 103-N is positioned at Xi3 along the X-axis; (e) the optical grating outputs of each of the three optical waveguides 103-4, 103-5, and 103-6 are aligned along the X axis; (f) the optical grating outputs of each of the two optical waveguides 103-2, 103-7 are aligned along the X axis at Xe2; (g) the optical grating output of each of the two optical waveguides 103-1, 103-N is arranged along the X axis at Xe3; (h) the optional input optical waveguide portion 111 of each of the two optical waveguides 103-1, 103-N begins at Xin on the X-axis and has a length Lin3; (i) the optional input optical waveguide portion 111 of each of the two optical waveguides 103-2, 103-7 begins at Xin on the X-axis and has a length Lin2; (j) the optional input optical waveguide portion 111 of each of the three optical waveguides 103-3, 103-4, 103-5 begins at Xin on the X-axis and has a length Lin1; (k) the optional input optical waveguide portion 112 of each of the two optical waveguides 103-1, 103-N begins at Xe1 on the X-axis and has a length Lend1; (l) The optional input optical waveguide portion 112 of each of the two optical waveguides 103-2, 103-7 begins at Xe2 on the X-axis and has a length Lend2.

[0013] Optionally, the grating amplitude of each optical grating portion increases along or parallel to the first axis.

[0014] FIG. 1A illustrates a plan view of an exemplary optical grating (or optical grating) 100 configured to emit an optical beam having a predetermined cross-sectional shape and / or predetermined optical intensity across a cross-section through which the light exits. The optical grating 100 includes N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N, where N is an integer greater than 2. Each optical waveguide includes a periodic optical grating portion 104 in at least a portion of the optical waveguide, an optional input optical waveguide portion 111, and optional end optical waveguide portions 112. For instructional purposes, each optical waveguide illustrated in FIG. 1A is illustrated as including the optional input optical waveguide portion 111. Each of the optional input and optional end optical waveguide portions 111, 112 does not include an optical grating. Optionally, the optical grating 100 is on, eg, formed on, a substrate 115 .

[0015] The optical grating 100 receives a collimated optical signal 101 incident on an optical grating input 105 of the optical grating 100. 1 and converting the collimated optical signal 101 into an optical beam emitted from the optical grating 100. The third axis is orthogonal to each of the first (X) axis and the second (Y) axis. 1 A collimated optical signal is illustrated in FIG. 1A as propagating along the X-axis.

[0016] FIG. 1B illustrates a cross-sectional view of an exemplary optical grating 100 in accordance with an embodiment of the present invention, emitting an optical beam 110 having a predetermined cross-sectional shape 110-1 and an optical intensity present within cross-sectional shape 110-1. Optical beam 110 has a component in a third (Z) axis and, optionally, a component in a first (X) axis. Optical grating 100 lies in a plane 114 defined by the first (X) axis and a second (Y) axis. While FIG. 1B illustrates a single optical beam 110, embodiments of the present invention can emit two or more optical beams in different directions from an optical grating, e.g., an optical grating portion.

[0017] FIG. 1C illustrates a diagram of an exemplary cross-sectional shape 110-1 of an optical beam emitted by optical grating 100. For teaching purposes, the illustrated cross-sectional shape 110-1 is an ellipse with a constant optical intensity where light resides within cross-sectional shape 110-1. The cross-sectional shape of the emitted optical beam does not necessarily have to be the same as the cross-section of the grating section. However, the cross-sectional shape can be any shape, such as a circle, a letter, a number, etc. The illustrated cross-sectional shape 110-1 lies in a plane defined by a fourth axis (X') and a fifth axis (Y'), where the fourth and fifth axes are orthogonal.

[0018] 1A , the lengths of each of the two or more optical grating sections 104 may be different, and thus (a) the locations of each grating input of the two or more optical grating sections may be different, and / or (b) the locations of each grating end of each of the two or more optical grating sections may be different. The length of the optical grating is the length L of the optical waveguide minus the sum of (a) the length Lin_n of the input optical waveguide section (if used) and (b) the length Lend_n of the end optical waveguide section (if used). The input optical waveguide section and / or the end optical waveguide section are optionally part of each optical waveguide. The optical grating sections define apertures 117.

[0019] The period P of the optical grating sections 104 of each of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N may or may not be the same. The period P is a function of the wavelength of the collimated optical signal incident on the optical grating 100 and the desired output direction of one or more optical beams emitted from the grating section, where each of the two or more optical beams may be emitted in a different direction from the grating section.

[0020] Each period of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N has a modulation amplitude MA1, MA2, MA3. For teaching purposes, each optical grating portion 104 has a width 2is illustrated as being implemented using an optical waveguide in which a length of the end waveguide portion is periodically reduced and expanded. Optionally, each end waveguide portion and each input waveguide portion has the same height along or parallel to the third axis as each input waveguide portion. 2 In FIG. 1A, width is along the Y axis.

[0021] However, the optical grating section 104 may be implemented with periodic recesses at each height of, for example, N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N. Therefore, the modulation amplitude may be implemented differently for different types of optical grating sections. For example, for an optical grating section formed by such recesses, the modulation amplitude is the depth of each recess. For instructional purposes, embodiments of the present invention are illustrated using the grating structure illustrated in FIG. 1A.

[0022] The structure of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, and 103-N illustrated in FIG. 1A will now be further described. FIG. 2A illustrates a plan view of an optical waveguide 203 of the optical grating 100. The optical waveguide 203 includes an optional input optical waveguide portion 211, an optical grating portion 214, and optional end optical waveguide portions 212. The optional input optical waveguide portion 211 has a first length L1. The optical grating portion 204 has a second length L2. The optional end optical waveguide portion 212 has a third length L3. Each of the first and third lengths L1 and L3 is greater than or equal to zero. The first length L1 may or may not be equal to the third length L3. The second length L2 is greater than zero.

[0023] Each optical grating section 214 includes an optical grating input 228 and an optical grating end 229. Each of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N includes an optical waveguide input 227. The optical waveguide input 227 of each of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N is either the input of an optional input optical waveguide section 211 or the optical grating input 228 of the optical grating section 214 if the optical waveguide does not include the optional input optical waveguide section 211. The optical grating input 105 includes an optical waveguide input 227 for each of N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N.

[0024] FIG. 2B illustrates a cross-sectional view of one embodiment of optional input optical waveguide portion 211, for example, at line AA-AA′ in FIG. 2A . For teaching purposes, optional optical waveguide portion and optical grating portion are illustrated herein as being formed of planar optical waveguides. However, such components may be formed of other types of optical waveguides, for example, optical fibers. Optionally, optional input optical waveguide portion 211 includes a core 223 surrounded by a cladding 224. Optionally, optional input optical waveguide portion 211 is on substrate 215. The refractive index of core 223 is greater than the refractive index of cladding 224. Optionally, core 223 is formed of silicon nitride. Optionally, cladding 224 is formed of silicon dioxide. The illustrated cross-section of the core of optional input optical waveguide portion 211 has a first width W1.

[0025] 2C illustrates a cross-sectional view of one embodiment of optical grating portion 204, for example, at line BB-BB' in FIG. 2A. The cross-section of optical grating portion 204 illustrated in FIG. 2C is similar to the cross-section of the optional optical transmission line, except that the second width W2 of the core of the cross-section is smaller than the first width W1.

[0026] Figure 2D illustrates a cross-sectional view of one embodiment of optical grating portion 204, for example, at line CC-CC' in Figure 2A. The cross-section of optical grating portion 204 illustrated in Figure 2D is similar to the cross-sections illustrated in Figures 2B and 2C, except that the third width W3 of the core in the cross-section illustrated in Figure 2D is greater than each of the first width W1 and second width W3.

[0027] Returning to FIG. 1A, the grating strength, which is a function of grating amplitude, of the optical grating of the optical waveguides may vary or may be constant in each of the N optical waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-N.

[0028] 3 illustrates a flow diagram of one embodiment of a method 330 for emitting an optical beam from an optical grating fabricated in accordance with an embodiment of the present invention. The method illustrated herein may be implemented using the optical grating 100 illustrated and described with respect to FIGS. 1A-2D, but may likewise be implemented in other manners, for example, using other types of grating structures.

[0029] The blocks of the flow diagrams are generally organized sequentially for ease of explanation. However, it should be understood that this organization is merely exemplary and that the processing associated with the methods described herein (and the blocks illustrated in the figures) may occur in a different order (e.g., at least some of the processing associated with the blocks may be performed in a parallel and / or event-driven manner).

[0030] In block 331, a collimated optical signal is received at the input of an optical grating embodiment described elsewhere herein. In block 333, an optical beam is emitted from an aperture of the optical grating, as described elsewhere herein.

[0031] While the present teachings have been illustrated with respect to one or more embodiments, variations and / or modifications to the illustrated embodiments may be made without departing from the scope of the appended claims. In addition, while certain features of the present disclosure may be described with respect to only one of several embodiments, such features may be combined with one or more features of other embodiments as may be desirable and advantageous for any given or particular function. Furthermore, to the extent that terms such as "including," "includes," "having," "has," "with," or variations thereof are used in either the Detailed Description and / or the Claims, such terms are intended to be as inclusive as the term "comprising." The term "at least one of" is used to mean that one or more of the listed items may be selected. As used herein, the term "one or more of," with respect to a list of items, such as A and B, or A and / or B, means A only, B only, or A and B. The term "at least one of" is used to mean that one or more of the listed items may be selected.

[0032] Relative position terms used in this application are defined based on a plane parallel to a conventional plane or working surface of a material (e.g., a layer or substrate), regardless of orientation. Terms such as "on," "higher," "lower," "over," "top," and "under" are defined with respect to a conventional plane or working surface that is the top surface of a layer or substrate, regardless of orientation. The terms "about" or "substantially" indicate that a specified value or parameter may be slightly modified as long as such modification does not result in non-compliance of the process or structure with the illustrated embodiment. Finally, "exemplary" indicates that the description does not imply ideality but is used as an example. While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that any configuration expected to achieve the same purpose may be substituted for the specific embodiment shown. Therefore, it is manifestly intended that this invention be limited only by the claims and equivalents thereof.

[0033] Illustrative Embodiments Example 1 is an optical grating in a plane defined by a first axis and a second axis orthogonal to the first axis, configured to receive a collimated optical signal propagating parallel to the first axis at an optical grating input of the optical grating and further configured to emit an optical beam from an aperture of the optical grating, the optical grating comprising N optical waveguides, each comprising a waveguide input, a waveguide end, and an optical grating section comprising the grating input and the grating end, N being an integer greater than 1, the apertures being defined by the optical grating sections, each optical waveguide in the plane and parallel to each other optical waveguide of the N optical waveguides, and at least two of the N optical waveguides and (b) each grating input of at least two of the N optical waveguides is located at a different position along or parallel to the first axis, and each grating end of at least two of the N optical waveguides is located at a different position along or parallel to the first axis, and (b) the grating amplitude varies between at least two optical grating portions in at least one position along or parallel to the second axis, wherein each optical waveguide whose optical grating portion begins after a waveguide input along or parallel to the first axis does not have an optical grating and further comprises an input optical waveguide portion optically connecting the waveguide input to the grating input.

[0034] Example 2 includes the optical grating of example 1, wherein the grating amplitude varies along or parallel to the first axis in at least one optical grating portion.

[0035] Example 3 includes the optical grating of example 2, wherein the grating amplitude of each optical grating portion increases along or parallel to the first axis.

[0036] Example 4 includes the optical grating of any of Examples 1 to 3, wherein each end waveguide portion and each input waveguide portion has the same height as each input waveguide portion along or parallel to a third axis, and the third axis is orthogonal to each of the first and second axes.

[0037] Example 5 includes the optical grating of any of Examples 1 to 4, wherein each of the N optical waveguides comprises a planar optical waveguide.

[0038] Example 6 includes the optical grating of any of Examples 1 to 5, wherein each of the optical grating portions comprises periodically expanding and contracting a width of the optical waveguide, the width being along or parallel to the second axis.

[0039] Example 7 includes the optical grating of any of Examples 1-6, wherein each of the N optical waveguides includes a core surrounded by a cladding, and the refractive index of the core is greater than the refractive index of the cladding.

[0040] Example 8 includes the optical grating of any of Examples 1-7, further comprising a substrate, wherein each of the N optical waveguides is on the substrate.

[0041] Example 9 includes the optical grating of any of Examples 1-8, wherein the optical grating input includes an optical waveguide input for each of the N optical waveguides.

[0042] Example 10 includes a method for emitting an optical beam from an optical grating, the method including receiving a collimated optical signal propagating parallel to a first axis at an optical grating input of the optical grating, and emitting the optical beam from an aperture of the optical grating, the optical grating being in a plane defined by the first axis and a second axis orthogonal to the first axis, and including N optical waveguides, each comprising an optical grating section having a waveguide input, a waveguide end, and a grating input and a grating end, N being an integer greater than 1, the aperture being defined by the optical grating section, each optical waveguide being in the plane and parallel to each other optical waveguide of the N optical waveguides, at least one of (a) each grating input of two or more of the optical waveguides is positioned at a different position along or parallel to the first axis, and (b) each grating end of at least two of the N optical waveguides is positioned at a different position along or parallel to the first axis, and (b) the grating amplitude varies between at least two optical grating sections in at least one position along or parallel to the second axis, and each optical waveguide whose optical grating section begins after the waveguide input along or parallel to the first axis further comprises an input optical waveguide section that does not have an optical grating and optically connects the waveguide input to the grating input.

[0043] Example 11 includes the method of example 10, wherein the grating amplitude varies along or parallel to the first axis in at least one optical grating portion.

[0044] Example 12 is an optical grating in a plane defined by a first axis and a second axis orthogonal to the first axis, configured to receive a collimated optical signal propagating parallel to the first axis at an optical grating input of the optical grating and further configured to emit an optical beam from an optical grating portion of the optical grating, the optical grating including N optical waveguides each including a waveguide input, a waveguide end, and an optical grating portion including the grating input and the grating end, N being an integer greater than 1, each optical waveguide being in the plane and parallel to each other optical waveguide of the N optical waveguides, and each grating input of two or more of the N optical waveguides and at least one of: the grating amplitude varies between at least two optical grating portions at at least one location along a second axis or parallel to the second axis; and each optical waveguide whose optical grating portion begins after a waveguide input along or parallel to the first axis does not have an optical grating and further comprises an input optical waveguide portion optically connecting the waveguide input to the grating input.

[0045] Example 13 includes the optical grating of example 12, wherein the grating amplitude varies along or parallel to the first axis in at least one optical grating portion.

[0046] Example 14 includes the optical grating of example 13, wherein the grating amplitude of each optical grating portion increases along or parallel to the first axis.

[0047] Example 15 includes the optical grating of any of Examples 12 to 14, wherein each end waveguide portion and each input waveguide portion has the same height as each input waveguide portion along or parallel to a third axis, and the third axis is orthogonal to each of the first and second axes.

[0048] Example 16 includes the optical grating of any of Examples 12 to 15, wherein each of the N optical waveguides comprises a planar optical waveguide.

[0049] Example 17 includes the optical grating of any of Examples 12 to 16, wherein each of the optical grating portions includes periodically expanding and contracting a width of the optical waveguide, the width being along or parallel to the second axis.

[0050] Example 18 includes the optical grating of any of Examples 12-17, wherein each of the N optical waveguides includes a core surrounded by a cladding, and the refractive index of the core is greater than the refractive index of the cladding.

[0051] Example 19 includes the optical grating of any of Examples 12-18, further comprising a substrate, wherein each of the N optical waveguides is on the substrate.

[0052] Example 20 includes the optical grating of any of Examples 12-19, wherein the optical grating input includes an optical waveguide input for each of the N optical waveguides.

[0053] Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that any configuration which is expected to achieve the same purpose may be substituted for the specific embodiment shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

1. an optical grating in a plane defined by a first axis and a second axis orthogonal to the first axis, the optical grating being configured to receive a collimated optical signal propagating parallel to the first axis at an optical grating input of the optical grating, the collimated optical signal being further configured to emit an optical beam from an aperture of the optical grating; N optical waveguides, each comprising a waveguide input, a waveguide end, and an optical grating section comprising a grating input and a grating end, wherein N is an integer greater than 1, and the apertures are defined by the optical grating sections; each optical waveguide lies in the plane and is parallel to each of the other optical waveguides of the N optical waveguides; (a) (i) each grating input of two or more of the N optical waveguides is located at a different position along or parallel to the first axis; and (ii) at least one of: each grating end of at least two of the N optical waveguides is positioned at a different position along or parallel to the first axis; and (b) the grating amplitude differs between at least two optical grating portions at at least one location along or parallel to the second axis; an optical grating, wherein each optical waveguide whose optical grating portion begins after the waveguide input along or parallel to the first axis further comprises an input optical waveguide portion that does not have an optical grating and optically connects the waveguide input to the grating input.

2. The optical grating of claim 1 , wherein the grating amplitude varies along or parallel to the first axis in at least one optical grating portion.

3. The optical grating of claim 2 , wherein the grating amplitude of each optical grating portion increases along or parallel to the first axis.

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