Optical device comprising nanorod light emitters on a substrate

Abstract

A light source is provided that emits output light along an output path. The light source includes a substrate and a plurality of light emitters disposed on the substrate in the output path. Each light emitter has a footprint on the substrate and extends laterally from the substrate to the output path. Each light emitter includes quantum wells that emit output light when electrically biased. Further, each light emitter has a refractive index that is higher than the corresponding refractive index of the environment that contacts the light emitter outside the light emitter. Each light emitter may include nanorods, and each pair of adjacent nanorods may be spaced apart from each other along the output path by a distance of about λn / 2, where λ is the wavelength of the output light and n is a natural number.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 393,850, filed on July 30, 2022, the entire content of which is incorporated herein by reference.

[0002] This specification relates to optical devices, and more particularly to optical devices comprising one or more light emitters disposed on a substrate.

Background Art

[0003] Optical devices may use or manipulate light. This light may be generated by a light source. Some light sources may use solid light emitters to generate light.

Summary of the Invention

[0004] According to one aspect of this specification, a light source is provided that emits output light along an output path, the light source comprising a substrate and a plurality of light emitters disposed on the substrate in the output path, the light emitters each having a footprint on the substrate and extending laterally away from the substrate to the output path, the light emitters each comprising a quantum well that emits output light when electrically biased, the light emitters each having a refractive index higher than the corresponding refractive index of the environment abutting the light emitter outside the light emitter, the light emitters each comprising a nanorod, and each pair of adjacent nanorods being spaced apart from each other along the output path by a distance of about λn / 2, where λ is the wavelength of the output light and n is a natural number.

[0005] The light source may emit output light along an output direction along the output path, the most upstream of the nanorods with respect to the output direction may have a sidewall forming an upstream optical interface at its upstream end, the most downstream of the nanorods with respect to the output direction may have a corresponding sidewall forming a downstream optical interface at its downstream end, and the downstream optical interface may be shaped to increase the transmission of output light through the downstream optical interface relative to the corresponding transmission of output light through the upstream optical interface.

[0006] The light source may further comprise a support material disposed on the substrate, the emitter is at least partially embedded in the support material, the support material is substantially transparent to the output light, and the support material has a corresponding refractive index smaller than that of the emitter.

[0007] The support material may be a non-waveguide for the output light.

[0008] The outer boundary of the support material may not completely internally reflect the output light.

[0009] One or more of the outer boundaries may be roughened to reduce the reflectivity of the output light and / or angled to reduce the reflectivity of the output light.

[0010] The emitters may terminate at respective ends on the opposite side of their footprints on the substrate, the ends extend from the support material, and the light source may further comprise electrical contacts disposed on the support material and in electrical contact with the ends of the emitters.

[0011] At least one of the nanorods may be such that it at least partially absorbs the output light when at least one of the nanorods is reverse-biased.

[0012] According to another aspect of the present specification, a light source is provided that emits output light along an output path, the light source comprising a substrate and a light emitter disposed on the substrate in the output path, the light emitter having a footprint on the substrate and extending laterally away from the substrate to the output path, the light emitter comprising quantum wells that emit output light when electrically biased, the light emitter having a refractive index higher than the refractive index of the corresponding environment that abuts the light emitter outside the light emitter, the footprint having a first end and a second end along the output path, the light emitter having an optical dimension that is the distance between the first end and the second end along the output path, the optical dimension being about λn / 2, where λ is the wavelength of the output light and n is a natural number, and the light emitter comprising nanowalls.

[0013] The light source may emit output light along an output direction along the output path, the nanowall may have sidewalls that form an upstream optical interface at its upstream end, the nanowall may have corresponding sidewalls that form a downstream optical interface at its downstream end, and the downstream optical interface may be shaped to increase the transmission of output light through the downstream optical interface relative to the corresponding transmission of output light through the upstream optical interface.

[0014] The light source may further comprise one or more additional light emitters each comprising a nanorod, the nanorods being disposed on the substrate along the output path, each pair of adjacent nanorods being spaced apart from each other along the output path by a corresponding distance of about λp / 2, where λ is the wavelength of the output light and p is a natural number, and the nanowall being spaced apart from its one or more adjacent nanorods along the output path by a corresponding distance of about λm / 2, where λ is the wavelength of the output light and m is a natural number.

[0015] The light source may emit output light along an output direction along the output path, and a first number of one or more nanorods upstream of the nanowall with respect to the output direction may be greater than a second number of one or more nanorods downstream of the nanowall with respect to the output direction.

[0016] The light source may further comprise a support material disposed on the substrate, one or more light emitters are at least partially embedded within the support material, the support material is substantially transparent to the output light, and the support material has a corresponding refractive index that is less than the refractive index of the one or more light emitters.

[0017] The support material may be a non-waveguide for the output light.

[0018] The outer boundary of the support material may not completely internally reflect the output light.

[0019] One or more of the outer boundaries may be roughened to reduce the reflectivity with respect to the output light and / or angled to reduce the reflectivity with respect to the output light.

[0020] The light emitters may terminate at respective ends on opposite sides of their footprints on the substrate, the ends extend from the support material, and the light source may further comprise electrical contacts disposed on the support material and in electrical contact with the ends of the light emitters.

[0021] At least one of the one or more nanorods may be such that it at least partially absorbs the output light when at least one of the nanorods is reverse-biased.

[0022] According to yet another aspect of the present specification, an optical device is provided that amplifies input light propagating along an optical path. The optical device includes a substrate and a plurality of light emitters disposed on the substrate in an output path. Each light emitter has a footprint on the substrate and extends laterally away from the substrate to the optical path. Each light emitter is electrically biased and includes a quantum well that emits emitted light when exposed to the input light. The emitted light forms output light having an amplitude greater than the corresponding amplitude of the input light from the plurality of light emitters. Each light emitter has a refractive index higher than the corresponding refractive index of the environment abutting the light emitter outside the light emitter. Each light emitter includes a nanorod, and each pair of adjacent nanorods is separated from each other along the optical path by a distance of approximately (q + 1 / 4)∧, where ∧ is the wavelength of the input light and q is an integer greater than or equal to zero.

[0023] The optical device may further include a shell around one or more of the light emitters, and the one or more light emitters have a core-shell geometry.

[0024] The shell may be one that reduces the reflectivity of the light emitter of the input light.

[0025] The shell may have a thickness of approximately ∧ / 4 measured along the optical path.

[0026] The optical device may further include a support material disposed on the substrate, and one or more of the light emitters are at least partially embedded in the support material. The support material is substantially transparent to the input light and the output light, and the support material has a corresponding refractive index smaller than the refractive index of the light emitter.

[0027] The support material may be a non-waveguide for the input light and the output light.

[0028] The outer boundary of the support material may be one that does not completely internally reflect the input light and the output light.

[0029] One or more of the outer boundaries may be roughened to reduce the reflectivity with respect to the input light and the output light, and / or may be angled to reduce the reflectivity with respect to the input light and the output light.

[0030] The light emitters may terminate at respective ends on the opposite sides of their footprints on the substrate, the ends extending from the support material, and the optical device may further comprise electrical contacts disposed on the support material and in electrical contact with the ends of the light emitters.

[0031] A subset of the light emitters that are most downstream along the optical path may absorb the output light and emit a corresponding electrical signal when the subset is reverse-biased.

[0032] A subset of the light emitters along the optical path may modulate the output light when the subset of the light emitters is reverse-biased.

[0033] The optical device may further comprise a cavity between two of the light emitters, the cavity being within the optical path and opening to the corresponding environment outside the optical device, and the cavity allows an object to be inspected from the corresponding environment to enter the cavity and interact with one or more of the input light and the output light.

[0034] According to yet another aspect of the present specification, a method of operating an optical device is provided, the method comprising defining an input light as an intensity band moving along the optical path over time, and biasing a subset of the light emitters that fall within the intensity band, the subset changing along the optical path over time and aligning with the intensity band moving along the optical path over time.

[0035] The step of biasing a subset of the light emitters may include biasing the subset of the light emitters with a bias amplitude that increases along the optical path over time.

[0036] The method may further include the step of reverse-biasing a corresponding subset of the light emitters that are the most downstream along the optical path, wherein the corresponding subset of the light emitters absorbs the output light and emits a corresponding electrical signal.

[0037] According to yet another aspect of the present specification, a method of operating an optical device is provided. The method includes biasing a first subset of light emitters, wherein the first subset of light emitters is exposed to input light and emits emitted light to form output light; and reverse-biasing a second subset of light emitters, wherein the second subset of light emitters at least partially absorbs the output light.

[0038] The step of biasing the first subset of light emitters may include biasing the first subset of light emitters that are the most upstream along the optical path, and the step of reverse-biasing the second subset of light emitters may include reverse-biasing the second subset of light emitters that are the most downstream along the optical path, wherein the second subset of light emitters absorbs the output light and emits a corresponding electrical signal.

Brief Description of the Drawings

[0039] In the drawings, the same reference numerals identify similar elements or acts. The sizes and relative positions of the elements in the drawings are not necessarily drawn to scale. For example, the shapes and angles of the various elements are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and arranged to improve the visibility of the drawings. Further, the particular shapes of the drawn elements are not necessarily intended to convey any information regarding the actual shapes of the particular elements, but are simply selected to facilitate recognition in the drawings.

[0040]

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DETAILED DESCRIPTION OF THE INVENTION

[0041] In the following description, some specific details are set forth in order to provide a thorough understanding of the various disclosed implementations. However, one of ordinary skill in the art will recognize that the implementations may be practiced without one or more of these specific details, or with other methods, components, materials, etc.

[0042]

[0043] ​For the purposes of this specification, it should be understood that the language “at least one of X, Y, and Z” and “one or more of X, Y, and Z” can be interpreted as only X, only Y, only Z, or any combination of two or more of the items X, Y, and Z (e.g., XYZ, XY, YZ, ZZ, etc.). Similar logic can apply to any occurrence of the language “at least one...” and “one or more...” with respect to two or more items.

[0044] Unless the context dictates otherwise, throughout the following specification and claims, the word “comprise” and variations thereof (such as “comprises” and “comprising”) are to be interpreted in an open, inclusive sense, i.e., “including, but not limited to.”

[0045] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally used in its broadest sense, i.e., “and / or” unless the content clearly dictates otherwise.

[0046] The headings and summaries provided in this specification are for convenience only and do not interpret the scope or meaning of the implementations.

[0047] By using solid state light emitters, it may be possible to manufacture light sources in large quantities and at a relatively low cost per unit. In some examples, semiconductor and microelectronics manufacturing techniques may be used to manufacture such light sources. Additionally, such light sources may be more easily fabricated on-chip or otherwise integrated with electro-optic systems.

[0048] Furthermore, at the size scale where quantum confinement occurs, by controlling the physical dimensions of the light emitter, additional means can be provided to control the parameters of the output light generated by the light source. Examples of such parameters may include wavelength, wavelength distribution, etc. Such size scales may include, for example, the nanometer size scale. In some examples, the nanometer size scale may range from a few nanometers to several hundred nanometers. Furthermore, the nanometer size scale may sometimes also be referred to as the nanometer size scale or the nanoscale. Furthermore, at such size scales, the physical characteristics of the light source may interact with the output light to provide additional functionality. Examples of such interactions may include Bragg reflection, etc.

[0049] FIG. 1 shows a schematic side view of an exemplary light source 100 using a solid-state light emitter. The light source 100 includes a substrate 105 and a plurality of light emitter nanorods 110 disposed on the substrate 105. In some examples, the substrate may include, for example, a silicon wafer. The light source 100 emits output light along an output path 115. The nanorods 110 are disposed on the substrate 105 along the output path 115. Each of the nanorods 110 has a footprint on the substrate 105 and extends laterally away from the substrate 105 to the output path 115. In some examples, the dimensions of the footprint may be on the nanometer size scale. For example, in embodiments where the footprint is circular or substantially circular, the diameter of the footprint may be on the nanometer size scale. In some examples, it is also contemplated that the footprint may have a shape other than circular and that dimensions of the footprint other than the diameter may be on the nanometer size scale. In some examples, it is also contemplated that the dimensions of the footprint may be larger than the nanometer size scale, for example, the dimensions of the footprint may be on the single-digit micron scale, the two-digit micron scale, etc.

[0050] As shown in FIG. 1, the nanorod 110 extends away from the substrate 105 and outside the plane defined by the substrate 105. In FIG. 1, the output path 115 is on a plane substantially parallel to the plane defined by the substrate 105. In some examples, it is contemplated that the output path may deviate from being substantially parallel to the plane of the substrate.

[0051] The nanorod 110 extending laterally from the substrate to the output path 115 generally exhibits "side emission" of the output light by the nanorod 110. FIG. 1 shows the output path 115 that is substantially perpendicular to the height of the nanorod 110, but in some examples, it is contemplated that the output path 115 may deviate from being perpendicular to the height of the nanorod. In some examples, the output path 115 may deviate from perpendicular to the height of the nanorod by up to about ±5°, up to about ±10°, up to about ±15°, up to about ±20°, up to about ±30°, up to about ±40°, etc. The footprint of the nanorod 110 is shown and further described in connection with FIG. 2.

[0052] Each of the nanorods 110 includes a quantum well that emits output light when the emitter nanorod is electrically biased. The nanorod 120 is an example of the nanorod 110. The nanorod 120 includes a quantum well 125. Other of the nanorods 110 also include similar quantum wells. The quantum well 125 may include a region or portion of the nanorod 120 that can emit light when the nanorod 120 and the quantum well 125 are electrically biased. In some examples, the quantum well 125 may include a semiconductor material. By electrically biasing, electrons may be excited across the energy levels (e.g., bandgap) of this semiconductor material. When these excited electrons relax to lower energy levels, photons of the output light may be emitted. In some examples, it is also contemplated that the emitter of the light source may comprise or be formed with a quantum cascade laser geometry instead of or in addition to a quantum well.

[0053] In some examples, the size of the footprint of the nanorod 120 may have a quantum confinement effect on the quantum well 125, whereby the degree of quantum confinement affects the energy levels and the size of the bandgap of the quantum well. By using this quantum confinement effect, the wavelength of the output light emitted by the emitter nanorod may be adjusted by adjusting the size of the footprint of the nanorod. Further, by reducing the size of the footprint of the nanorod 110, the crystal dislocations within the nanorod 110 can be more easily relaxed, thereby obtaining a higher quality luminescent material.

[0054] Further, FIG. 1 shows a quantum well 125 in the shape of a discrete band in a nanorod, but in some examples it is contemplated that the quantum well may have a different shape, size, or distribution in an emitter such as the nanorod 110. For example, each nanorod may comprise a plurality of bands or relatively large quantum well bands, and the quantum wells may form a core-shell structure or be part thereof, etc.

[0055] The emitter nanorod 110 has a refractive index higher than the refractive index of the environment abutting the nanorod 110 outside the nanorod 110. By the operation of Snell's law, such a relatively high refractive index enables the emitted output light to be internally reflected by the emitter nanorod and directed along the output path. Further, in the light source 100, each pair of adjacent nanorods 110 are spaced apart from each other by a Bragg distance along the output path 115. The Bragg equation is as follows: nλ = 2dSinθ

[0056] Since the output light propagating along the output path 115 is substantially perpendicular to the nanorods 110 (i.e., θ is approximately 90°), Sinθ is approximately 1. Therefore, the Bragg distance d can be expressed as nλ / 2, where λ is the wavelength of the output light and n is a natural number. In other words, in the light source 100, each pair of adjacent nanorods 110 is spaced apart from each other along the output path 115 by a distance 130 of approximately nλ / 2, where λ is the wavelength of the output light and n is a natural number.

[0057] Due to this spacing, the light emitted by one of the nanorods can interfere with the light emitted by other nanorods so as to reinforce it and become in phase with the light emitted by other nanorods. As a result, it may be possible for the light emission by one nanorod to stimulate the light emission from other nanorods. In this way, the light source 100 may achieve coherent induced optical emission or laser oscillation. Furthermore, by selecting the Bragg spacing, it may also be possible to select and narrow the wavelength emitted by the light source 100.

[0058] FIG. 1 shows the nanorods 110 as being spaced apart from each other by the same distance. However, in some examples, it is contemplated that the distances between different pairs of adjacent nanorods may be different as long as those distances are integer multiples of λ / 2. In other words, in some examples, the nanorods do not have to be evenly spaced as long as the spacing between pairs of adjacent nanorods is an integer multiple of λ / 2.

[0059] Furthermore, in FIG. 1, the distance 130 is marked between the outer walls of adjacent nanorods, but in some examples, it is contemplated that the distance 130 can be defined or measured between the center points of adjacent nanorods. This center point may be the midpoint of the respective width of the nanorod, and the width may be the dimension of each nanorod along the output path 115. Further, in some examples, the width of each nanorod may also be a natural multiple of λ / 2. In some examples, it is also contemplated that the nanorods may have different attributes such as their widths, the shapes of their footprints, heights, etc.

[0060] Since the light source 100 is symmetric in both directions along the output path 115, the light source 100 emits light in both directions along the output path 115. To guide or direct the output light in one of those directions, the symmetry of the structure of the light source may be reduced. Examples of such less symmetric light sources will be described in connection with FIGS. 3, 4, and 7 - 10.

[0061] The light source 100 also includes a support material 135 on the substrate 105. The emitter nanorods 110 are partially embedded in the support material 135, and the support material 135 is substantially transparent to the output light emitted by the nanorods 110. In some examples, being substantially transparent may include being at least about 70% transparent, at least about 80% transparent, at least about 90% transparent, at least about 95% transparent, etc.

[0062] The support material 135 has a refractive index smaller than that of the emitter nanorods 110. In some examples, the support material 135 may comprise a dielectric solid material such as SiN, SiO2, etc. The support material 135 may provide physical or mechanical support for the nanorods 110. Further, the support material 135 may passivate the surface of the nanorods 110. By such passivation, the nanorods may be protected from damage by external agents. The support material 135 may also provide a support on which the electrical contacts 140 can be deposited or formed. Examples of the formation stages of the nanorods and the support material and examples of passivation will be further discussed in connection with FIGS. 11A - 11E.

[0063] In FIG. 1, the support material 135 is shown by a dashed line, which is to indicate that in some examples, the light source 100 need not comprise a solid support material. In some examples, air or another fluid may surround the nanorods.

[0064] Furthermore, in the light source 100, the support material 135 is a non-waveguide. In other words, the support material 135 may be designed to reduce or even not have the ability to internally reflect the output light, particularly along the output path, to guide the output light. As described above, the emitter nanorods 110 have a higher refractive index than the environment outside the nanorods. In an example of a light source having a solid support material, this environment may include the support material. When the refractive index of the nanorods is relatively high, the nanorods can guide and direct the output light. By designing the support material to be a non-waveguide, redundancy or interference between the waveguiding of the support material and the waveguiding function of the nanorods can be prevented.

[0065] Furthermore, in some examples, the emitters of the light sources described herein may form a resonant cavity for the output light. By designing the support material to be a non-waveguide, it is possible to prevent the support material from acting as a second resonant cavity, and as a result, reduce or eliminate the coupled cavity parasitics that may arise from the support material cavity interacting with the resonant cavity formed by the emitter.

[0066] In some examples, to improve the non-waveguide quality of the support material, the outer boundary of the support material 135 may not completely internally reflect the output light. In some such examples, one or more of the outer boundaries of the support material may be angled to reduce the reflectivity with respect to the output light. In FIG. 1, the boundary 145 of the support material 135 is angled in a zigzag pattern to reduce the reflection of the output light and improve the non-waveguide quality of the support material 135. In some examples, it is also contemplated that shapes or angles other than zigzag may be used to reduce the reflectivity of the boundary of the support material with respect to the output light.

[0067] Furthermore, in some examples, instead of or in addition to being angled, one or more outer boundaries of the support material may be roughened to reduce reflectivity with respect to the output light. Other means of reducing reflectivity or internal reflectivity at or of the outer boundary of the support material, such as beam absorbers, beam dumps, etc., are also contemplated.

[0068] As shown in FIG. 1, the emitter nanorods 110 terminate at each end, such as end 150. These ends are on the opposite side of the footprint of the nanorods on the substrate 105. In the light source 100, these ends extend outside the support material 135. In some examples, etching (e.g., partial etching of the support material) or the like may be used to expose the nanorod ends. The light source 100 also includes electrical contacts 140 disposed on the support material 135 and in electrical contact with the ends of the emitter nanorods 110. The electrical contacts 140 may be used to supply power to the nanorods 110 and electrically bias the nanorods 110 to emit output light.

[0069] In FIG. 1, the electrical contacts 140 are shown in dashed lines, which is to indicate that in some examples, the light source 100 need not include the electrical contacts 140. In some such embodiments, the electrical contacts may be on the substrate 105 or located elsewhere within the light source 100. Further, in some examples, it is contemplated that the ends of the nanorods need not extend outside the support material. In some such examples, the ends of the nanorods may be substantially flush with the support material or may be slightly recessed within the support material.

[0070] Furthermore, in some examples, during operation, one or more of the nanorods 110 may at least partially absorb the output light when the nanorods are reverse-biased. This reverse bias may be used to attenuate or turn off the output light emitted by the light source. In some examples, this reverse bias control may be used to pulse or otherwise control the output light.

[0071] Referring now to FIG. 2, a top view of the light source 100 as seen through the electrical contact 140 is shown. In FIG. 2, the footprint of the emitter nanorods 110 on the substrate 105 is shown. FIG. 2 shows the nanorods 110 as having a circular footprint, although in some examples it is contemplated that the nanorods may have different shaped footprints such as hexagonal, faceted, or other shapes. Further, FIG. 2 shows all of the nanorods 110 as having the same footprint, although in some examples the nanorods may have footprints with different characteristics such as shape, size, etc.

[0072] In FIG. 2, the side surfaces 205 and 210 of the support material 135 are shown as having an irregular shape in order to reduce reflection of the output light. Further, the side surfaces are shown with dashed lines, which in some examples indicates that the side surfaces 205 and 210 may be angled, shaped, roughened, or placed at a distance from the emitter in a different manner in order to reduce reflection of the output light.

[0073] FIG. 3 shows a schematic side view of an exemplary light source 300. The light source 300 is similar to the light source 100, except that in the light source 300, the symmetry along the output path is reduced, allowing the light source 300 to preferentially emit output light along one output direction 315 along the output path. In the light source 300, this reduction in symmetry is achieved by changing the shape of the emitter optical interface that is furthest downstream with respect to the output direction 315.

[0074] The light source 300 includes emitter nanorods 310, a substrate 105, a support material 335, and electrical contacts 340. The nanorods 310 are generally similar to the nanorods 110, except that in the nanorods 310, the nanorod 350 that is furthest downstream with respect to the output direction 315 is different in that it is different from the other nanorods. The support material 335 and the electrical contacts 340 are similar to the support material 135 and the electrical contacts 140, respectively.

[0075] In the light source 300, the further upstream of the nanorod 310 with respect to the output direction 315 (i.e., the nanorod 120) has a side wall 345 forming an upstream optical interface at its upstream end. Further, the most downstream of the nanorod 310 with respect to the output direction 315 (i.e., the nanorod 350) has a side wall 355 forming a downstream optical interface at its downstream end. In the light source 300, the downstream optical interface is shaped differently from the upstream optical interface so as to change the transmission of the output light through the downstream optical interface with respect to the transmission of the output light through the upstream optical interface. This change in shape can be seen in FIGS. 3 and 4. This relative change in the transmittance of the output light enables control over the direction in which the output light is emitted. In some examples, this change may include an increase in the transmission of the output light through the side wall 355.

[0076] As shown in FIG. 3, in the light source 300, the relative change in light transmission at the downstream optical interface (i.e., the side wall 355) is achieved by changing and curving the shape of the side wall 355. Such curvature may also provide a lens effect and further modify the output light. In some examples, it is also contemplated that the downstream optical interface may be changed in different ways, for example, by changing interface attributes such as shape, angle, roughness, etc.

[0077] Further, in some examples, in order to control the direction of emission or propagation of the output light from the light source 300, the reflectivity of the output light at the upstream optical interface may be increased (thereby the transmittance may be decreased). For example, a portion of the support material 335 (e.g., the side wall 345) in contact with the upstream optical interface may be removed to increase the difference or change in refractive index between the upstream side and the downstream side of the upstream optical interface. This increase in the refractive index change may then increase the reflection of the upstream optical interface with respect to the output light.

[0078] Further, in some examples, the width of the most upstream nanorod can be reduced to be much smaller than the wavelength of the output light. The width of the nanorod may be the dimension of the nanorod along the output direction 315. In some examples where the nanorod has a circular footprint, the width may include the diameter of the nanorod.

[0079] Further, in some examples, the upstream optical interface may include a grating reflector. Such a grating may be passive or active. In some examples, the grating may include a curved element such as a curved nanowall. Further, in some examples, the grating may include or be formed from a support material formed in an array of Bragg interval reflectors. Generally, by varying the transmission of the output light at the first optical interface (e.g., sidewall 345) relative to the transmission at the second optical interface (e.g., sidewall 355), it may be possible to control the direction of emission or propagation of the output light from the light source 300.

[0080] FIG. 4 shows a schematic top view of the light source 300 as seen through the electrical contact 340. Similar to FIG. 2, in FIG. 4, the side surfaces 405 and 410 of the support material 335 are shown to be irregularly shaped to reduce reflection of the output light. Further, the side surfaces are shown by dashed lines, which in some examples indicates that the side surfaces 405 and 410 may be angled, shaped, roughened, or placed at a distance from the emitter in other ways to reduce reflection of the output light.

[0081] The light sources described herein can have various sizes and shapes. In some examples, the light source may define a rectangular prism having a length of about 0.5 - 1 mm, a width of about 1 - 2 μm along the output path, and rising above the substrate to a height of about 1 μm. Other shapes and sizes are contemplated. In some examples where the light source includes a non-waveguiding support material, the support material may have a width greater than about 5 μm, a width greater than about 10 μm, etc. Further, in some examples, the side surfaces or outer boundaries of such a support material may be oriented at an angle with respect to the axial direction of the nanorods, and that angle may exceed a threshold value. In some examples, this threshold value may be about 1° or another threshold value greater than 1°.

[0082] FIG. 5 shows a schematic side view of another exemplary light source 500. The light source 500 is similar to the light source 100, except that the emitter in the light source 500 includes a nanowall 510, while the emitter in the light source 100 is a nanorod 110. The light source 500 includes a substrate 105, a nanowall 510, a support material 535, and electrical contacts 540. The support material 535 and the electrical contacts 540 may be similar to the support material 135 and the electrical contacts 140, respectively.

[0083] The nanowall 510 may include quantum wells 525 that can emit light when electrically biased. The quantum wells 525 are shown as layers extending along a direction substantially parallel to the output path 115. However, in some examples, it is contemplated that the quantum wells may have a shape, size, or position within the nanowall that is different from that shown in FIG. 5. The nanowall 510 may have a width in the nanometer size range (visible in FIG. 6).

[0084] In some examples, the nanowall may have dimensions on the nanometer size scale. For example, the width or thickness of the nanowall may be on the nanometer size scale. In some examples, it is also contemplated that the nanowall may have larger dimensions. For example, the dimensions may be on the single-digit micron scale, two-digit micron scale, etc.

[0085] The nanowall 510 has a refractive index higher than the refractive index of the environment that abuts the nanowall outside the nanowall. Further, the footprint of the nanowall 510 has a first end 515 and a second end 520 along the output path 115. These ends include two of the sidewalls of the nanowall 510. The distance between the ends 515 and 520 may be described as an optical dimension 530. The optical dimension 530 of the nanowall 510 may be about λn / 2, where λ is the wavelength of the output light and n is a natural number. In the light source 500, the nanowall 510 may act as a waveguide and form a resonant cavity for the output light between the tips 515 and 520. FIG. 5 shows one nanowall, but in some examples, it is contemplated that the light source may include multiple nanowalls within the output path.

[0086] In other words, the light source 500 includes a substrate 105 and a light-emitting nanowall 510 disposed on the substrate 105 within the output path 115. The nanowall 510 has a footprint on the substrate 105 and extends laterally away from the substrate 105 to the output path 115. The nanowall 510 includes quantum wells 525 that emit output light when the nanowall 510 is electrically biased. The nanowall 510 has a refractive index higher than the refractive index of the corresponding environment that abuts the nanowall 510 outside the nanowall 510. The footprint of the nanowall 510 has a first end 515 and a second end 520 along the output path 115. The nanowall 510 has an optical dimension 530 that is the distance between the first end 515 and the second end 520 along the output path 115. The optical dimension 530 is approximately λn / 2, where λ is the wavelength of the output light and n is a natural number.

[0087] In some examples, the light source 500 also includes a support material 535 disposed on the substrate 105. The support material 535 may have a composition, structure, and function similar to those described for the support material 135. For example, the light emitter of the light source 500 may be at least partially embedded in the support material 535, and the support material has a refractive index lower than the refractive index of the light emitter. Further, the support material 535, like the support material 135, is a non-waveguide for the output light.

[0088] The nanowall 510 terminates at an end 550 on the opposite side of its footprint on the substrate 105. The end 550 extends from the support material 535. The light source 500 includes an electrical contact 540 disposed on the support material 535 and in electrical contact with the end 550 of the nanowall 510. Similar to the light source 100, in some examples, it is contemplated that the end 550 may be in the same plane as the support material 535 or recessed therein. Further, similar to the light source 100, in some examples, it is contemplated that the light source 500 need not include the electrical contact 540 or the solid support material 535.

[0089] Referring now to FIG. 6, a top view of the light source 500 as seen through the electrical contact 540 is shown. FIG. 6 shows the footprint of the emitter nanowalls 510 on the substrate 105. Although FIG. 6 shows the nanowalls 510 as having a rectangular footprint, in some examples, it is contemplated that the nanowalls can have footprints of different shapes or sizes.

[0090] In FIG. 6, the side surfaces 605 and 610 of the support material 535 are shown as having an irregular shape in order to reduce reflection of the output light. Further, the side surfaces are shown as dashed lines, which in some examples indicates that the side surfaces 605 and 610 may be angled, shaped, roughened, or placed at a distance from the emitter in a different manner in order to reduce reflection of the output light.

[0091] To control the radiation direction of the output light along the output path, one of the two ends of the nanowall may be modified to modify the transmission of the output light at one end relative to the transmission of the output light at the other end. FIG. 7 shows a schematic side view of an exemplary light source 700, where the radiation direction of the output light along the output path is controlled or adjusted.

[0092] The light source 700 is similar to the light source 500, except that in the light source 700, the optical interface at the end portion 720 is different in shape from the corresponding optical interface at the end portion 520 of the light source 500. This difference is clearly seen in FIG. 8. This change in shape changes the transmission of the output light at the tip 720 compared to the transmission of the output light at the end 715, thereby enabling the light source 700 to emit output light substantially along the output direction 315. In some examples, this change includes an increase in the transmission of the output light through the end 720.

[0093] The light source 700 includes a substrate 105, a nano-wall 710 having ends 715 and 720 along an output direction 315, a support material 735, and an electrical connector 740. The support material 735 and the electrical connector 740 may be similar to the support material 535 and the electrical connector 540, respectively. Further, in some examples, it is contemplated that the light source 700 need not include a solid support material or the electrical connector 740.

[0094] The nano-wall 710 has sidewalls at its upstream end 715 that form an upstream optical interface. The nano-wall 710 also has corresponding sidewalls at its downstream end 720 that form a downstream optical interface. The downstream optical interface is shaped to vary the transmission of output light through the downstream optical interface relative to the corresponding transmission of output light through the upstream optical interface. The shape of the downstream end 720 is clearly seen in FIG. 8.

[0095] As shown in FIG. 7, in the light source 700, the altered light transmission at the downstream optical interface (i.e., sidewall or tip 720) is achieved by changing and curving the shape of the tip 720. Such curvature may also provide a lens effect and further modify the output light. In some examples, it is also contemplated that the downstream optical interface may be varied in different ways, such as by changing attributes of the interface, such as shape, angle, roughness, etc. In some examples, the transmission of output light at the upstream optical interface relative to the transmission at the downstream optical interface may be modified using an approach similar to the approach described in connection with FIG. 3. Generally, it may be possible to control the direction of emission or propagation of the output light from the light source 700 by varying the transmission of the output light at the upstream optical interface (e.g., end 715) relative to the transmission at the downstream optical interface (e.g., end 720).

[0096] Referring now to FIG. 8, a top view of the light source 700 as seen through the electrical contact 740 is shown. In FIG. 8, the side surfaces 805 and 810 of the support material 735 are shown to have an irregular shape in order to reduce reflection of the output light. Further, the side surfaces are shown by dashed lines, which in some examples indicates that the side surfaces 805 and 810 may be angled, shaped, roughened, or placed at a distance from the emitter in other ways to reduce reflection of the output light.

[0097] In addition to changing the shape of the upstream or downstream optical interface, other methods of reducing symmetry may be used to control the direction of emission of the output light from the light source. One such method is to use both nanowalls and nanorods as emitters and asymmetrically distribute the nanorods on the substrate on both sides of the nanowall along the output path. When the nanorods are separated from each other by a natural multiple of the Bragg distance from the nanowall, the nanorods may act as at least partial Bragg mirrors to at least partially reflect the output light propagating along the output path. The higher the number of nanorods, the higher the reflectivity of such a Bragg mirror. If the number of nanorods upstream of the nanowall with respect to the output direction is greater than the number of nanorods downstream of the nanowall with respect to the output direction, the side with the larger number of nanorods may act substantially as a back mirror, and the side with fewer nanorods may act substantially as the light output interface from which the output light is emitted by the light source. FIG. 9 shows an example of such a light source.

[0098] FIG. 9 shows a schematic side view of yet another exemplary light source 900, which includes a substrate 905, a nanowall 510, a support material 935, and an electrical contact 940. The substrate 905, the support material 935, and the electrical contact 940 are each similar to the substrate 105, the support material 535, and the electrical contact 540, respectively. The light source 900 is similar to the light source 500, except that the light source 900 further includes emitter nanorods 120 disposed on the substrate 905 along an output path indicated by the output direction 315, respectively. The light source 900 includes seven nanorods, and those rods are similar or identical to each other in composition, structure, and function.

[0099] Each pair of adjacent nanorods is separated from each other along the output path by a distance 945 of approximately λp / 2, where λ is the wavelength of the output light and p is a natural number. Further, the nano-wall 510 is separated from its adjacent nanorod along the output path by a corresponding distance 950 of approximately λm / 2, where λ is the wavelength of the output light and m is a natural number. In FIG. 9, the distance to the nanorod is measured from the outer surface or side wall of the nanorod, but in some examples, it is contemplated that the distance may be measured from the center point of the nanorod. Further, FIG. 9 shows the distance 945 between pairs of nanorods as being equal and also the distance 950 as being equal, but in some examples, it is contemplated that these distances need not be equal to each other as long as the distances are approximately natural number multiples of λ / 2.

[0100] The light source 900 emits output light in a substantially long output direction 315 along the output path. The light source 900 has four nanorods upstream of the nano-wall 510 with respect to the output direction 315 and fewer, i.e., three nanorods, downstream of the nano-wall 510 with respect to the output direction 315. When the number of nanorods on the upstream side of the nano-wall 510 is relatively large, the reflectivity is higher on the upstream side than on the downstream side, and the transmittance of the output light decreases. Due to this relative difference in the transmittance of the output light, the light source 900 can emit light substantially along the output direction 315.

[0101] FIG. 9 shows the light source 900 as having four nanorods upstream of the nano-wall 510 and three nanorods downstream, but in some examples, it is contemplated that different numbers of nanorods may be used on either the upstream or downstream side of the nano-wall. Further, FIG. 9 shows the light source 900 as having one nano-wall and a plurality of nanorods, but in some examples, it is contemplated that the light source may have different numbers, combinations, and distributions of other types, structures, or shapes of nano-walls, nanorods, and solid light emitters.

[0102] In some examples, one or more of the nanorods in the light source 900 may be used to absorb the output light when those nanorods are reverse-biased. This light absorption may be used to control the output light, for example, by pulsing the output light. In some examples, it is also contemplated that the nanowalls may be reverse-biased to absorb the output light.

[0103] Referring now to FIG. 10, a top view of the light source 900 as viewed through the electrical contact 940 is shown. FIG. 10 shows the footprint of the emitter nanowalls 510 and the emitter nanorods on the substrate 905. FIG. 10 shows the nanowalls 510 as having a rectangular footprint and the nanorods as having a circular footprint, but in some examples, it is contemplated that the nanowalls or nanorods may have footprints of different shapes or sizes.

[0104] Further, in FIG. 10, the sides 1005 and 1010 of the support material 935 are shown as having an irregular shape to reduce reflection of the output light. Further, the sides are shown as dashed lines, which in some examples indicates that the sides 1005 and 1010 may be angled, shaped, roughened, or placed at a distance from the emitter in a different manner to reduce reflection of the output light.

[0105] Referring now to FIGS. 11A-11E, schematic side views of exemplary stages of manufacturing another exemplary light source 1100 are shown. The light source 1100 is shown in FIG. 11E. The light source 1100 may function in a similar manner as the light source 100 and may have components similar to those of the light source 100. FIG. 11A shows a side view of the substrate 1105 of the light source 1100. The substrate 1105 may be similar to the substrate 105. A patterned mask 1110 is formed on the substrate 1105. In some examples, the mask 1110 may comprise a refractive metal material or the like. The pattern of the mask 1110 may leave a gap 1115 on the substrate 1105, and nanorods may be formed within that gap.

[0106] Figure 11B shows nanorods 1120 formed on substrate 1105 within the gaps of mask 1110. Each nanorod 1120 includes a corresponding quantum well 1125. The nanorods 1120 and quantum wells 1125 may be similar to the nanorods 120 and quantum wells 125 respectively. The nanorods 1120 may be formed using a suitable deposition or growth technique such as a vacuum-based technique.

[0107] Figure 11C shows a shell 1130 formed on each of the nanorods 1120. Such a shell may also be formed using a suitable deposition or growth technique such as a vacuum-based technique. The shell 1130 may be used to passivate the nanorods 1120. In some examples, the shell 1130 may also be used to control the optical properties at the interface between the nanorods 1120 and the surrounding material. For example, the shell 1130 may be used to control the reflectivity at the surface of the nanorods by controlling the properties of the shell 1130, such as its refractive index and thickness. In some examples, the shell 1130 may be designed to be a reflectivity reduction layer for parasitic wavelengths or otherwise undesirable wavelengths. In some such examples, the shell 1130 may be designed to be a quarter-wavelength layer so as to act as an antireflection layer for any undesirable wavelengths.

[0108] Figure 11D shows a support material 1135 deposited in the space between the core-shell nanorods. The support material 1135 may be similar to the support material 135. In some examples, a vacuum-based technique may be used to deposit the support material 1135. In some examples, after forming the shell 1130, the vacuum may be broken and it is also contemplated that the support material 1135 may be deposited using a non-vacuum-based technique.

[0109] In FIGS. 11C and 11D, mask 1110 is shown to remain on substrate 1105 after forming shell 1130 and depositing support material 1135. However, in some examples, it is contemplated that mask 1110 can be selectively removed either before forming shell 1130 or before forming shell 1130 and depositing support material 1135.

[0110] FIG. 11E shows electrical contact 1140 formed on support material 1135 and in contact with nanorod 1120. Electrical contact 1140 may be similar to electrical contact 140. Electrical contact 1140 can be used to supply power or apply a bias to nanorod 1120. In some examples, the light sources and the formation stages of light source 1100 described in connection with FIGS. 11A-11E may also be applicable to other optical devices described herein, including light sources comprising nanorods, light sources comprising one or more nanowalls, and light sources comprising a combination of one or more nanowalls and one or more nanorods.

[0111] Referring now to FIG. 12, a schematic side view of an exemplary optical device 1200 is shown. Optical device 1200 is similar to light source 1100, except that in optical device 1200, the space 1205 between two adjacent nanorods is not filled with support material. Space 1205 is open to the environment surrounding optical device 1200, potentially allowing materials in the environment to enter space 1205 and interact with the light propagating inside optical device 1200. This interaction can then potentially allow materials from the environment to affect the light output by optical device 1200. By monitoring the effect of such an interaction on the output light, optical device 1200 can potentially act as a sensor. In some examples, leaving one or more open spaces similar to space 1205 is contemplated to be applicable to other light sources described herein, including light sources comprising nanorods, light sources comprising one or more nanowalls, and light sources comprising a combination of one or more nanowalls and one or more nanorods.

[0112] In the optical devices (including light sources and sensors) described herein in connection with FIGS. 1-12, the path of light is shown as a straight line. In some examples, it is also contemplated that the light emitter can be arranged such that the optical path forms a closed shape of a "ring resonator". Examples of such closed shapes may include a circle, an ellipse, etc. Optical devices having a "ring resonator" geometric shape may also be used for sensing, including sensing using cavity ring-down spectroscopy, etc.

[0113] In some examples, such a "ring resonator" geometric shape may also include one or more of a light inlet for injecting light into the ring resonator and a light outlet for outputting light from the ring resonator. Further, in some examples, the "ring resonator" geometric shape may be applied to the light sources described herein, including light sources comprising nanorods, light sources comprising one or more nanowalls, and light sources comprising a combination of one or more nanowalls and one or more nanorods.

[0114] FIG. 13 shows a schematic top view of an exemplary optical device 1300 comprising a ring resonator 1305. In some examples, the ring resonator 1305 may have a diameter on the millimeter to centimeter size scale. Other size ranges and scales are contemplated. The ring resonator 1305 is formed using a plurality of nanorod light emitters 1310 disposed on a substrate. The nanorod light emitters 1310 and their substrates may each be similar to the nanorods 120 and the substrate 105, as well as other nanorods and substrates described herein. The difference between the optical device 1300 and the light source 100 is that in the optical device 1300, the nanorod light emitters are arranged along a circle such that the optical path of the light passing through the nanorod light emitters is substantially circular. In this way, the nanorods 1310 can form the ring resonator 1305.

[0115] The optical device 1300 may also include an optical inlet 1315 for injecting light into the ring resonator 1305 and an optical outlet 1320 for outputting light from the ring resonator 1305. In FIG. 13, the optical inlet 1315 and the outlet 1320 are shown by dashed lines, and in some examples, it is not necessary for the optical device to include one or more of the optical inlet or the optical outlet, or one or more of the optical inlet and the optical outlet may have a shape, size, or position with respect to the ring resonator 1305 that is different from the shape, size, and position shown in FIG. 13.

[0116] In some examples, it is contemplated that the optical device 1300 may have characteristics or functions similar to those of other light sources and optical devices described herein. In some examples, it is also contemplated that the optical device 1300 may include other types of light emitters, such as nanowalls, as an addition or alternative to some or all of the nanorods 1310. In some examples, the optical device 1300 may be used for sensing, including sensing using cavity ring-down spectroscopy or the like.

[0117] In the optical devices described in connection with FIGS. 1-13, the light emitter is electrically biased and then emits light. These optical devices may have different functions, such as functions of a light source, a sensor, etc. In some examples, the light emitter may be electrically biased and then exposed to input light. The input light may then stimulate or cause the biased light emitter to emit light. The emitted light may have the same wavelength and k-vector as the input light. The induced emission light from the light emitter may form output light having an amplitude or intensity greater than that of the input light. In this way, the optical device may be used as an optical amplifier. FIG. 14 shows an example of such an optical amplifier.

[0118] FIG. 14 shows a schematic side view of an exemplary optical amplifier 1400. The amplifier 1400 may be similar to the light source 100, and the amplifier 1400 includes a plurality of nanorod emitters 120-1, 120-2, 120-3, 120-4, 120-5, 120-6, 120-7, and 120-8 disposed on a substrate 105. For clarity, the nanorods in the amplifier 1400 may be the same as the nanorods in the light source 100. In particular, the nanorod 120-1 of the amplifier 1400 is the same as the nanorod 120 of the light source 100, and the difference in the number of components is intended to facilitate the explanation in relation to FIG. 14. The difference between the amplifier 1400 and the light source 100 is that in the amplifier 1400, the distance 1405 between adjacent nanorod emitters is different from the distance 130 in the light source 100. This difference will be explained in more detail below.

[0119] The amplifier 1400 may function to amplify the input light 1410 to form the output light 1415. The arrow indicating the input light 1410 in FIG. 14 shows the optical path along which the input light 1410 may travel or propagate. The amplifier 1400 includes a substrate 105 and a plurality of emitters 120-1 to 120-8 disposed on the substrate 105 within the optical path. Although FIG. 14 shows eight emitters, it is contemplated that the amplifier 1400 may include fewer or more emitters.

[0120] Each emitter has a footprint on the substrate 105 and extends laterally away from the substrate 105 into the optical path. Each emitter includes a corresponding quantum well 125 and emits light when the emitter is electrically biased and exposed to the input light 1410. The light emitted from the plurality of emitters may form an output light 1415 having an amplitude greater than the corresponding amplitude of the input light 1410. In some examples, the light emitted from the emitters may combine to form the output light 1415. Further, in some examples, the output light 1415 may include a superposition of the light emitted from the emitters with respect to amplitude or intensity. In this way, the amplifier 1400 may amplify the input light 1410 to form the output light 1415.

[0121] Each light emitter may have a refractive index higher than the corresponding refractive index of the environment that abuts the light emitter outside the light emitter. Thereby, along the optical path, near the light emitter, it may help to substantially retain the optical energy of the input light 1410, the emitted light, and the output light 1415 propagating within the amplifier 1400. In this way, the position of the light emitter may function to define the optical path.

[0122] Furthermore, to facilitate the input light 1410 propagating through the amplifier 1400 to stimulate the electrically biased light emitter to emit emitted light, the spacing or distance between the light emitters may be set to reduce or minimize the reflection of the input light (or emitted light and output light having the same wavelength as the input light) at the surface of the light emitter along the optical path. In some examples, the distance between the light emitters may be set to a Bragg minimum. In other words, each pair of adjacent nanorods may be spaced apart from each other along the optical path by a distance of approximately (q + 1 / 4)∧, where ∧ is the wavelength of the input light and q is an integer greater than or equal to zero. In yet other words, the distance 1405 may be approximately (q + 1 / 4)∧, where ∧ is the wavelength of the input light and q is an integer greater than or equal to zero. Thus, the distance 1405 may be different from the distance 130 at the light source 100.

[0123] Furthermore, in some examples, the nanorod surface may be tilted at approximately the Brewster angle to help reduce or minimize the reflection of the input light (or emitted light and output light having the same wavelength as the input light) at the surface of the light emitter along the optical path, which can be particularly effective for a polarized input optical signal.

[0124] The spacing between the light emitters may also be adjusted according to the wavelength of the input light 1410. In other words, the spacing may be set to be approximately at the Bragg minimum with respect to the wavelength of the input light. In this way, the input light (as well as the emitted light and the output light having the same wavelength as the input light) may propagate through the amplifier 1400 while reducing or minimizing reflection at the surface of the light emitters within the optical path. Other parasitic wavelengths may be reflected to a relatively large extent at the surface of the light emitters. Therefore, these parasitic wavelengths may be attenuated or at least partially filtered out by selecting the spacing between the light emitters.

[0125] Furthermore, as shown in FIG. 14, the light emitter may comprise a nanorod. In some examples, it is also contemplated that the amplifier may comprise a light emitter having a shape other than a nanorod, in addition to or in place of one or more of the nanorods. Some examples of light emitters having other shapes may include nanowalls and the like. Part or all of the structures or geometries described in connection with FIGS. 2-13 may also be used to implement an optical amplifier, provided that the distance between adjacent light emitters or adjacent optical reflection interfaces is adjusted to reduce or minimize reflection at the wavelength of the input light.

[0126] Furthermore, in some examples, the amplifier may comprise a shell around one or more of the light emitters such that the light emitter may have a core-shell geometry. Examples of such architectures are described in connection with FIGS. 11A-11E. Furthermore, in some examples, such a shell may function to reduce the reflectivity of the light emitter at the wavelength of the input light. In other words, the shell may reduce the reflectivity of the light emitter of the input light. Furthermore, in some examples, the shell may have a thickness of approximately λ / 4 measured along the optical path.

[0127] Furthermore, the amplifier may also comprise a support material disposed on the substrate. FIG. 14 shows a support material 135 disposed on the substrate 105. The characteristics and functions of this support material in the context of the amplifier may be the same as the corresponding support material characteristics and functions described in relation to the optical devices described in FIGS. 1-13.

[0128] In some examples, one or more of the light emitters may be at least partially embedded in the support material, and the support material may be substantially transparent to the input and output light. Further, the support material may have a corresponding refractive index that is less than the refractive index of the light emitter.

[0129] Furthermore, in some examples, the support material may be a non-waveguide for the input and output light. For example, the outer boundary of the support material may not completely internally reflect the input and output light. In some examples, one or more of such outer boundaries may be roughened to reduce the reflectivity with respect to the input and output light. Further, in some examples, one or more of the outer boundaries may be angled to reduce the reflectivity with respect to the input and output light.

[0130] As shown in FIG. 14, the light emitters terminate at their respective ends (e.g., end 150) on the opposite side of their footprints on the substrate 105. The ends extend outside the support material 135. The amplifier 1400 also comprises an electrical contact 140 disposed on the support material and in electrical contact with the ends of the light emitters. The electrical contact 140 may be used to electrically bias one or more of the light emitters. In this specification, "electrical bias" may be abbreviated as "bias".

[0131] As described above, during operation, at least some of the light emitters may be electrically biased. When these biased light emitters are exposed to the input light, the input light may stimulate the light emitters or, alternatively, cause the light emitters to emit emitted light having the same wavelength as the input light. In some examples, a subset of the light emitters may be reverse biased. The magnitude of this reverse bias may be the same as or different from the magnitude of the bias. These reverse biased light emitters may at least partially absorb one or more of the input light and the output light.

[0132] In some examples, one or more reverse biased light emitters may absorb the light propagating within the amplifier (i.e., at least a portion of the input light and the output light) and emit or generate a corresponding electrical signal. This absorption of the output light and the corresponding generation of the electrical signal may be used to sense or detect the input light. In this way, the optical device may function as a combination of an amplifier and a photodetector. Such a combination may be used, in the case of a weak optical signal, by first amplifying the input light and then detecting or sensing it.

[0133] To enable enhanced amplification prior to sensing, in some examples, a subset of the light emitters that are most downstream along the optical path may be reverse biased to absorb the output light and emit a corresponding electrical signal. For example, referring to FIG. 14, during operation, the nanorod light emitters 120-1 to 120-6 may be biased, and the light emitters 120-7 and 120-8 may be reverse biased. In some examples, it is contemplated that more, fewer, or different light emitters may be biased, and more, fewer, or different light emitters may be reverse biased.

[0134] At least a portion of the output light from the reverse-biased emitter may be absorbed, and the output light may also be modulated. For example, the amplitude of the output light may be reduced, or the output light may be turned off. The ability to modulate the output light may also enable the output light to be pulsed. Thus, in some examples, a subset of the emitters along the optical path may modulate the output light when the subset of emitters is reverse-biased.

[0135] Referring now to FIG. 15, a flowchart of an exemplary method 1500 for operating an optical amplifier comprising a plurality of emitters, such as amplifier 1400, is shown. In block 1505, a first subset of the emitters may be biased. This first subset may be exposed to input light, emit emitted light, and form output light. In block 1510, a second subset of the emitters may be reverse-biased. This second subset may at least partially absorb the output light.

[0136] As described above, the absorption of the output light by the reverse-biased emitter may be used for one or more of modulating the amplitude of the output light and sensing the output light. To improve the combined amplification and sensing functionality, in some examples, the reverse-biased subset of the emitters may be the most downstream along the optical path. In such examples, the method of operating the amplifier may include biasing a first subset of the emitters that are the most upstream along the optical path and reverse-biasing a second subset of the emitters that are the most downstream along the optical path. The second subset of the emitters may at least partially absorb the output light and emit a corresponding electrical signal.

[0137] When an emitter is electrically biased, in addition to the light emission stimulated by the input light, it may also receive spontaneous emission (SE) and emit light spontaneously. Such SE may be independent of the input light. Further, in some examples, the SE light may have a wavelength different from that of the input light. Thus, the SE light may represent parasitic light emission or noise during the operation of an optical amplifier such as amplifier 1400.

[0138] One way to reduce SE noise and improve the signal-to-noise ratio during the operation of the amplifier may be to electrically bias a subset of the light emitters that coincide with the optical intensity band representing the input optical signal. The remaining light emitters may not be biased or may be reverse biased. As the intensity band moves through the amplifier over time along the optical path, the subset of biased light emitters may also change over time in alignment with the moving intensity band. This mode of operation is further described in connection with FIGS. 16-18C. By reducing the number of light emitters that are electrically biased at any given time, this mode of operation may reduce SE noise during the operation of the amplifier.

[0139] Referring now to FIG. 16, a flowchart of an exemplary method 1600 for operating an optical amplifier having a plurality of light emitters, such as amplifier 1400, is shown. In block 1605, the input light may be defined as an intensity band that moves along the optical path over time. In block 1610, a subset of the light emitters that fall within the intensity band may be electrically biased. The subset may change over time along the optical path in alignment with the intensity band that moves along the optical path over time. An exemplary implementation of method 1600 is further described in connection with FIGS. 17A-18C.

[0140] Figures 17A - 17C show an exemplary scheme for biasing a subset of emitters that fall within the intensity band of the input light. Figure 17A shows amplifier 1400 at time t1, where the input light intensity band is aligned with a subset of emitters comprising nanorod emitters 120 - 1 and 120 - 2. These same two nanorods are biased, while the remaining nanorod emitters are not. Figure 17B shows amplifier 1400 at a later time t2, where the input light intensity band has moved along the optical path and is aligned with another subset of emitters comprising nanorod emitters 120 - 3 and 120 - 4. Nanorod emitters 120 - 3 and 120 - 4 are the two biased nanorods, while the remaining nanorod emitters are not.

[0141] Further, Figure 17C shows amplifier 1400 at a later time t3, where the input light intensity band has moved further along the optical path and is aligned with yet another subset of emitters comprising nanorod emitters 120 - 5 and 120 - 6. Nanorod emitters 120 - 5 and 120 - 6 are the two biased nanorods, while the remaining nanorod emitters are not. As shown in Figures 17A - 17C, only the subset of nanorod emitters aligned with the intensity band of the input light is biased.

[0142] In some examples, it is contemplated that at any given time, the intensity band may be aligned with fewer or more than two emitters. Figures 17A - 17C show only snapshots of the system at times t1, t2, and t3, but it is contemplated that other subsets of nanorod emitters may be biased, not biased, or reverse - biased at times t1, t2, t3, and at other times. For example, another subset of emitters may be reverse - biased to modulate or sense the output light. In some examples, in an operating mode that combines an amplifier and a photodetector, the reverse - biased subset may be the most downstream along the optical path, absorb the output light, and emit a corresponding electrical signal.

[0143] The input signal propagates along the optical path through the amplifier, and the signal is amplified by the stimulated emission light from the biased emitter, and the intensity of the input light increases over time. This is shown in FIGS. 18A to 18C. In FIGS. 17A to 17C, for ease of explanation, the intensity of the input light is shown as constant. To increase the amplification level of the amplifier 1400, the nanorod emitter may be biased at a larger size. As a side effect of this relatively high amplitude bias, SE noise may increase. As the amplitude or intensity of the input optical signal becomes stronger over time, a subset of the emitters may be correspondingly biased at a larger size to increase the amplification level while maintaining the signal-to-SE noise ratio within an acceptable level. In other words, a subset of the emitters may be biased at a bias magnitude that increases along the optical path over time. In this way, as the signal is amplified and becomes stronger over time, more SE noise may be tolerated to allow for a larger level of amplification while maintaining the signal-to-SE noise ratio within an acceptable level. Such an increase in the level of emitter subset bias is shown in FIGS. 18A to 18C.

[0144] FIGS. 18A to 18C show another exemplary scheme for biasing a subset of the emitters that fall within the intensity band of the input light. FIG. 18A shows the amplifier 1400 at time t1, and the input light intensity band is aligned with a subset of the emitters comprising the nanorod emitters 120-1 and 120-2. These are two nanorods biased at size v1, while the remaining nanorod emitters are not biased. FIG. 18B shows the amplifier 1400 at a later time t2, and the input light intensity band moves along the optical path and is aligned with another subset of the emitters comprising the nanorod emitters 120-3 and 120-4. The nanorod emitters 120-3 and 120-4 are two nanorods biased at a larger size v2, while the remaining nanorod emitters are not biased.

[0145] Furthermore, FIG. 18C shows the amplifier 1400 at a later time t3, where the input optical intensity band has moved further along the optical path and is aligned with yet another subset of the emitters comprising the nanorod emitters 120-5 and 120-6. The nanorod emitters 120-5 and 120-6 are two nanorods biased at a larger size v3, while the remaining nanorod emitters are unbiased. As shown in FIGS. 18A-18C, only the subset of nanorod emitters aligned with the intensity band of the input light is biased.

[0146] In some examples, it is contemplated that at any given time, the intensity band may be aligned with fewer or more than two emitters. FIGS. 18A-18C show only snapshots of the system at times t1, t2, and t3, but it is contemplated that other subsets of the nanorod emitters may be biased, unbiased, or reverse-biased at times t1, t2, t3, and at other times. For example, another subset of the emitters may be reverse-biased to modulate or sense the output light. In some examples, in an operating mode that combines an amplifier and a photodetector, the reverse-biased subset may be the most downstream along the optical path, absorb the output light, and emit a corresponding electrical signal.

[0147] An input optical signal may be amplified and detected using the amplifiers described herein. If the input light, emitted light, or output light can interact with an inspection target from the environment outside the amplifier, the amplifier may be used to also detect the inspection target. For example, the optical device 1200 shown in FIG. 12 has the spacing between the light emitters set in a manner similar to that described in relation to FIG. 14, and if the optical device 1200 is enabled to act as an amplifier, it may function as such an amplifier detector. Such an amplifier may include a cavity between two of the light emitters. This cavity is in the optical path and may be open to the corresponding environment outside the optical device. The cavity may allow an inspection target from the environment to enter the cavity and interact with one or more of the input light, emitted light, and output light.

[0148] Similarly, the geometric shape of the ring resonator described in relation to FIG. 13 may also be used as an amplifier if the spacing between the light emitters is set in a manner similar to the method described in relation to FIG. 14, and the optical device 1300 may also function as an amplifier.

[0149] In some examples, the geometric shapes of other optical devices described herein, for example, the geometric shapes described in relation to FIGS. 3 to 11E, may also be used as amplifiers if the spacing between the light emitters or the related optical interfaces is adjusted in a manner similar to that described in relation to FIG. 14, and it is contemplated that those devices may also function as amplifiers. For example, referring to FIGS. 5 and 6, in some examples, the optical dimension 530 may be set to be (q + 1 / 4)∧, where ∧ is the wavelength of the input light and q is an integer equal to or greater than zero. In this way, the optical devices of FIGS. 5 and 6 with the nano-walls 510 may be used as amplifiers. In order to further reduce the reflection of the input light and the output light at the first end 515 and the second end 520, in some examples, one or more of these ends may be set at the Brewster angle.

[0150] Furthermore, in some examples, it is contemplated that different emitters or different subsets of emitters may be biased simultaneously at different levels or magnitudes to achieve different electro-optic effects. Additionally, in some examples, a subset of nanorods may be biased to be transparent (to the input and output light). These nanorods may produce different optical effects and may function, for example, as a reflective Bragg back mirror for light having wavelengths other than the wavelengths of the input and output light. Other spatial arrangements of the emitters and other electrical bias patterns are also contemplated.

[0151] As described herein, in some examples, the present disclosure may have the following features. (Feature 1) An optical device that amplifies input light propagating along an optical path, a substrate, a plurality of emitters disposed on the substrate in the optical path, each of the emitters having a footprint on the substrate and extending laterally from the substrate to the optical path, each of the emitters being electrically biased and comprising a quantum well that emits emitted light when exposed to the input light, the emitted light forming output light having an amplitude greater than the corresponding amplitude of the input light from the plurality of emitters, each of the emitters having a refractive index higher than the corresponding refractive index of the environment abutting the emitter outside the emitter, a plurality of emitters; comprising, each of the emitters comprising a nanorod, each pair of adjacent nanorods being separated from each other along the optical path by a distance of approximately (q + 1 / 4)∧, where ∧ is the wavelength of the input light and q is an integer greater than or equal to zero, an optical device. (Feature 2) The optical device according to Feature 1, further comprising a shell around one or more of the emitters, the one or more emitters having a core-shell geometry. (Feature 3) The optical device according to Feature 2, wherein the shell reduces the reflectivity of the emitter of the input light. (Feature 4) The shell is the optical device according to Feature 3, having a thickness of approximately λ / 4 measured along the optical path. (Feature 5) The optical device according to any one of Features 1 to 4, further comprising a support material disposed on the substrate, wherein one or more of the light emitters are at least partially embedded in the support material, the support material is substantially transparent to the input light and the output light, and the support material has a corresponding refractive index smaller than the refractive index of the light emitter. (Feature 6) The optical device according to Feature 5, wherein the support material is a non-waveguide for the input light and the output light. (Feature 7) The optical device according to Feature 6, wherein the outer boundary of the support material does not totally internally reflect the input light and the output light. (Feature 8) One or more of the outer boundaries are roughened to reduce the reflectivity with respect to the input light and the output light, and angled to reduce the reflectivity with respect to the input light and the output light, and are one or more of the above, being the optical device according to Feature 7. (Feature 9) The light emitters terminate at respective ends on opposite sides of their footprints on the substrate, the ends extending from the support material, The optical device according to any one of Features 5 to 8, further comprising electrical contacts disposed on the support material and in electrical contact with the ends of the light emitters. (Feature 10) A subset of the light emitters that are most downstream along the optical path absorb the output light and emit a corresponding electrical signal when the subset is reverse-biased, being the optical device according to any one of Features 1 to 9. (Feature 11) The subset of the light emitters along the optical path modulates the output light when the subset of the light emitters is reverse-biased, the optical device according to any one of features 1 to 9. (Feature 12) The optical device according to any one of features 1 to 11, further comprising a cavity between two of the light emitters, the cavity being in the optical path and opening to a corresponding environment outside the optical device, and the cavity allowing an inspection target from the corresponding environment to enter the cavity and interact with one or more of the input light and the output light. (Feature 13) A method of operating the optical device according to feature 1, comprising: defining the input light as an intensity band that moves along the optical path over time; biasing a subset of the light emitters that falls within the intensity band, the subset changing along the optical path over time and aligning with the intensity band that moves along the optical path over time; A method comprising. (Feature 14) The method according to feature 13, wherein the step of biasing the subset of the light emitters comprises biasing the subset of the light emitters with a bias amplitude that increases along the optical path over time. (Feature 15) A step of reverse-biasing a corresponding subset of the light emitters that is most downstream along the optical path, the corresponding subset of the light emitters absorbing the output light and emitting a corresponding electrical signal. The method according to feature 13 or 14, further comprising. (Feature 16) A method of operating the optical device according to feature 1, comprising: biasing a first subset of the light emitters, the first subset being exposed to the input light and emitting the emitted light to form the output light; Biasing a second subset of the phosphor, wherein the second subset of the phosphor at least partially absorbs the output light, A method comprising. (Feature 17) The step of biasing the first subset of the phosphor includes biasing the first subset of the phosphor that is most upstream along the optical path, The step of reverse-biasing the second subset of the phosphor is to reverse-bias the second subset of the phosphor that is most downstream along the optical path, wherein the second subset of the phosphor absorbs the output light and emits a corresponding electrical signal, The method according to feature 16, comprising.

[0152] Throughout this specification and the appended claims, the infinitive form of the verb is often used. Examples include, but are not limited to, "emit", "increase", "decrease", etc. Unless otherwise required in a particular context, such infinitive forms of the verb are used in an open and inclusive sense, i.e., in the sense of "at least emit", "at least increase", "at least decrease", etc.

[0153] The above description of the illustrated exemplary implementation is not intended to be exhaustive or to limit the implementation to the exact form disclosed. Specific implementation forms and examples are described herein for purposes of illustration, but various equivalent modifications can be made without departing from the spirit and scope of the present disclosure, as will be recognized by those skilled in the art. Further, the various exemplary implementation forms described herein may be combined to provide further implementation forms.

[0154] Generally, in the following claims, the terms used should not be construed as limiting the claims to the specific implementations disclosed in this specification and the claims, but rather the claims should be construed to include all possible implementations along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the present disclosure.

Claims

1. A light source that emits output light along an output path, the light source comprising: a substrate; a plurality of light emitters disposed on the substrate in the output path, each light emitter having a footprint on the substrate and extending laterally from the substrate to the output path, each light emitter comprising a quantum well that emits the output light when electrically biased, and each light emitter having a refractive index higher than the refractive index of the corresponding environment that contacts the light emitter outside the light emitter; a plurality of light emitters; comprising; each of the light emitters comprises a nanorod; A light source, wherein each pair of adjacent nanorods is spaced apart from each other along the output path by a distance of about λn / 2, where λ is the wavelength of the output light and n is a natural number.

2. The light source emits the output light along an output direction along the output path, The most upstream of the nanorods with respect to the output direction has a side wall that forms an upstream optical interface at its upstream end, The most downstream of the nanorods with respect to the output direction has a corresponding side wall that forms a downstream optical interface at its downstream end, The light source according to claim 1, wherein the downstream optical interface is shaped to increase the transmission of the output light through the downstream optical interface relative to the corresponding transmission of the output light through the upstream optical interface.

3. The light source according to claim 1 or 2, further comprising a support material disposed on the substrate, the light emitter being at least partially embedded in the support material, the support material being substantially transparent to the output light, and the support material having a corresponding refractive index smaller than the refractive index of the light emitter.

4. The light source according to claim 3, wherein the support material is a non-waveguide for the output light.

5. The light source according to claim 4, wherein the outer boundary of the support material does not totally internally reflect the output light.

6. One or more of the outer boundaries are roughened to reduce the reflectivity of the output light, angled to reduce the reflectivity of the output light The light source according to claim 5, which is one or more of.

7. Each of the light emitters terminates at each end on the opposite side of their footprints on the substrate, the ends extending from the support material, The light source according to any one of claims 3 to 6, further comprising an electrical contact disposed on the support material and in electrical contact with the end of the light emitter.

8. The light source according to any one of claims 1 to 7, wherein at least one of the nanorods at least partially absorbs the output light when the at least one nanorod is reverse biased.

9. A light source that emits output light along an output path, the light source comprising: a substrate; a light emitter disposed on the substrate in the output path, the light emitter having a footprint on the substrate and extending away from the substrate in a direction transverse to the output path, the light emitter comprising a quantum well that emits the output light when the light emitter is electrically biased, the light emitter having a refractive index higher than the refractive index of the corresponding environment in contact with the light emitter outside the light emitter, the footprint having a first end and a second end along the output path, the light emitter having an optical dimension that is the distance between the first end and the second end along the output path, the optical dimension being about λn / 2, where λ is the wavelength of the output light and n is a natural number; a light emitter; A light source comprising: comprising The light emitter comprises a nanowall, the light source.

10. The light source emits the output light along an output direction along the output path, The nanowall has sidewalls that form an upstream optical interface at its upstream end, The nanowall has corresponding sidewalls that form a downstream optical interface at its downstream end, The light source according to claim 9, wherein the downstream optical interface is shaped to increase the transmission of the output light through the downstream optical interface relative to the corresponding transmission of the output light through the upstream optical interface.

11. Further comprising one or more additional light emitters each comprising a nanorod, the nanorod Disposed on the substrate along the output path, Each pair of adjacent nanorods is spaced apart from each other along the output path by a corresponding distance of about λp / 2, where λ is the wavelength of the output light and p is a natural number, The light source according to claim 9, wherein the nanowall is spaced apart from one or more of its adjacent nanorods along the output path by a corresponding distance of about λm / 2, where λ is the wavelength of the output light and m is a natural number.

12. The light source emits the output light along an output direction along the output path, The light source according to claim 11, wherein a first number of the one or more nanorods upstream of the nano-wall with respect to the output direction is greater than a second number of the one or more nanorods downstream of the nano-wall with respect to the output direction.

13. The light source according to any one of claims 9 to 12, further comprising a support material disposed on the substrate, wherein the one or more light emitters are at least partially embedded in the support material, the support material is substantially transparent to the output light, and the support material has a corresponding refractive index smaller than the refractive index of the one or more light emitters.

14. The light source according to claim 13, wherein the support material is a non-waveguide for the output light.

15. The light source according to claim 14, wherein an outer boundary of the support material does not totally internally reflect the output light.

16. One or more of the outer boundaries are roughened to reduce the reflectivity with respect to the output light, and angled to reduce the reflectivity with respect to the output light and one or more of the above, the light source according to claim 15.

17. The light emitter terminates at each end on the opposite side of their footprint on the substrate, and the ends extend from the support material, The light source according to any one of claims 13 to 16, further comprising an electrical contact disposed on the support material and in electrical contact with the ends of the light emitter.

18. The light source according to any one of claims 11 to 17, wherein at least one of the one or more nanorods absorbs at least part of the output light when the at least one nanorod is reverse-biased.

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