Spectrally Selective Optical Elements

Abstract

An example includes an optical element. The optical element includes a first optical material structure with a first refractive index across a frequency spectrum. The optical element also includes a second optical material structure configured to exhibit a change in refractive index from the first refractive index to a second refractive index across a portion of the frequency spectrum, and a refractive index anomaly corresponding to the change from the second refractive index to the first refractive index along the frequency spectrum. The optical element further includes a diffractive interface corresponding to a non-planar material contact junction between the first optical material structure and the second optical material structure. The diffractive interface can be configured to steer a light beam having a light path through the diffractive interface and having a frequency in the portion of the frequency spectrum in a predetermined manner.

Description

[Technical field]

[0001] The present disclosure relates generally to optical systems, and more particularly to spectrally selective optical elements. [Background technology]

[0002] Manipulating electromagnetic waves has become increasingly prevalent in a variety of technologies, including healthcare, remote sensing, navigation, and communications. Optical systems may require the functionality to manipulate light waves across a broad frequency spectrum, but often only selected bands within this range are required for instrument purposes. Optical systems can utilize optical phenomena to manipulate electromagnetic waves. For example, the Christiansen effect describes the reduction in scattering observed when different materials have the same refractive index. However, when the refractive index differs between two surfaces of nearly the same material, scattering and interaction of optical wavefronts at the interface between these surfaces is enhanced in a manner proportional to the difference in refractive index between the surfaces. Diffractive light control structures that realize the Christiansen effect typically only perform useful functions over the diffractive optical bandwidth for the useful range of refractive optical systems. Outside of the high efficiency diffraction band, a given diffractive light control structure may actually degrade the optical performance of the entire optical system, such as by acting as a source of scattering that contributes to the background noise of the associated optical instrument. Summary of the Invention

[0003] An example includes an optical element. The optical element includes a first optical material having a first refractive index across a frequency spectrum. The optical element also includes a second optical material structure configured to exhibit a change in refractive index from the first refractive index to a second refractive index across a portion of the frequency spectrum, and a refractive index anomaly corresponding to the change from the second refractive index to the first refractive index along the frequency spectrum. The optical element further includes a diffractive interface corresponding to a non-planar material contact junction between the first optical material structure and the second optical material structure. The interface can be configured to steer a light beam having a light path through the diffractive interface and having a frequency in the portion of the frequency spectrum in a predetermined manner.

[0004] Another example includes a method for manufacturing an optical element. The method includes providing a first optical material structure formed from a substrate material and having a first refractive index across a frequency spectrum; providing a second optical material structure formed from the substrate material. The method also includes introducing a refractive index-affecting impurity into the second optical material structure to facilitate a change in refractive index from the first refractive index to a second refractive index across a portion of the frequency spectrum, and the development of a refractive index anomaly corresponding to the change from the second refractive index to the first refractive index along the frequency spectrum. The method also includes forming an optical diffractive structure on a surface of one of the first and second optical material structures, and forming a complementary structure on a surface of the other of the first and second optical material structures. The method further includes bonding the first and second optical material structures through the surfaces of the first and second optical material structures to form a diffractive interface between the first and second optical material structures. The diffractive interface can be configured to steer a light beam having an optical path through the diffractive interface and having a frequency in a portion of the frequency spectrum in a predetermined manner.

[0005] Another example includes an optical system. The system includes a first optical element in the optical path of the light beam. The first optical element includes a first optical material structure with a first refractive index across the frequency spectrum. The first optical element also includes a second optical material structure configured to exhibit a first refractive index anomaly corresponding to a change in refractive index from the first refractive index to a second refractive index across a first portion of the frequency spectrum and a change from the second refractive index to the first refractive index along the frequency spectrum. The first optical element further includes a first diffractive interface corresponding to a first non-planar material contact junction between the first optical material structure and the second optical material structure. The first diffractive interface can be configured to manipulate a light beam having a frequency in the first portion of the frequency spectrum in a predetermined manner. The system also includes a second optical element in the optical path of the light beam. The second optical element includes a third optical material structure with a first refractive index across the frequency spectrum. The second optical element also includes a fourth optical material structure configured to exhibit a change in refractive index from the first refractive index to a third refractive index across a second portion of the frequency spectrum, and a second refractive index anomaly corresponding to the change from the third refractive index to the first refractive index along the frequency spectrum. The second optical element further includes a second diffractive interface corresponding to a second non-planar material contact junction between the third optical material structure and the fourth optical material structure. The second diffractive interface can be configured to manipulate a light beam having a frequency in the second portion of the frequency spectrum in a predetermined manner. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating an example of an optical element. [Diagram 2] FIG. 2 is a diagram showing another example of the optical element. [Diagram 3] FIG. 3 is a diagram showing an example of a graph of the refractive index and a graph of the diffraction efficiency of an optical element. [Figure 4] FIG. 4 shows a diagram of an example optical system and corresponding graphs of the refractive index and diffraction efficiency of the optical system. [Diagram 5] FIG. 5 is a diagram illustrating an example of a method for manufacturing an optical element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present disclosure relates generally to optical systems, and in particular to spectrally selective optical elements. Spectrally selective optical elements (hereinafter "optical elements") can be fabricated to include a first optical material structure and a second optical material structure, each of which corresponds to the same substrate material. The second optical material structure can include a refractive index-affecting impurity that can facilitate the development of a refractive index anomaly. As described herein, the term "index anomaly" corresponds to a change in refractive index from a nominal index of refraction of a substrate material over a well-defined spectral range. Such an index anomaly can be created in a variety of ways, but typically can be created by incorporating an absorption characteristic at a lower wavelength of light from the desired location of the index anomaly. This difference can be determined, for example, by the Kramers-Kronig relationship.

[0008] As an example, the diffraction efficiency of an optical element such as a diffractive optical element (DOE) can depend on the central design wavelength λ and the diffraction order m, where m ranges from 1 to ∞ and the wavelength of light, expressed as:

[0009]

number

[0010] For any given substrate material, absorption features can generate attenuation within the material. For example, the Kramers-Kronig relation can ensure that these absorption features also appear as refractive index changes in the material. Many materials have dispersion relations that are well described by the Sellmeier or Cauchy dispersion models. In the field of ellipsometry, these dispersion models are often augmented by distributions related to the dispersion phenomena caused by specific absorption features. In such cases, a Lorentzian distribution is often incorporated into the total dispersion curve to capture the refractive index change of the material immediately following a strong absorption feature. For example, a refractive index anomaly may force an optical element (e.g., a DOE) to operate only near the desired absorption band.

[0011] The product of the Lorentzian distribution (e.g. due to an absorber) and the diffractive optical efficiency provides the efficiency of the resulting optical element. To model possible refractive index anomalies, the Lorentzian amplitude can be scaled by the magnitude of the refractive index change (e.g. Δn(λ)=n2(λ)-n1(λ), ​​where λ denotes the spectral dependence of the refractive indices of media 1 and 2). The magnitude of the refractive index change can indicate the strength of the interaction of the wavefront with the diffractive surface of the optical element. If this difference is negligible, the performance of the optical element can be dominated by its behavior as a refractive element. Examples of such optical elements can be simple, such as a window, or complex, such as an aspheric corrector plate, a beam director, or an imaging lens in a telescope.

[0012] In the described optical element, a first refractive index corresponding to the nominal refractive index of the substrate material changes to a second refractive index over a portion of the frequency spectrum and then back to the first refractive index along the frequency spectrum. Thus, the second optical material structure can exhibit a different refractive index for wavelengths (e.g., in the wavefront of the light beam) of a light beam having a wavelength in that portion of the frequency spectrum. As described herein, the terms "wavelength" and "frequency" are used interchangeably since wavelength and frequency are inversely related. Thus, the wavelength of the light beam is described as existing within a frequency spectrum, and the frequency spectrum is described herein in terms of wavelength.

[0013] The first optical material structure and the second optical material structure can be arranged flush with each other in contact. Therefore, based on the combination of the first optical material structure and the second optical material structure, the light beam passing through the first optical material structure and the second optical material structure can undergo the Christiansen effect. Therefore, the light beam having a wavelength outside that part of the frequency spectrum may not be affected by the optical element. However, the light beam having a wavelength in that part of the frequency spectrum may undergo scattering (e.g., interaction) between the surfaces based on the difference in the refractive index between the first optical material structure and the second optical material structure.

[0014] The optical element includes a diffractive interface corresponding to a non-planar material contact junction between a first optical material structure and a second optical material structure. The diffractive interface can manipulate light beams in parts of the frequency spectrum where the refractive index between the substrate and the doped material differs significantly. As an example, the optical element can have spectral selectivity with respect to providing coherent interaction with the optical element resulting from the Christiansen effect, which is based on the fact that two surfaces with the same refractive index exhibit minimal scattering and exhibit maximum interaction when the refractive index between the substrates is at its maximum. As a result, the dispersion of light exhibited by the substrate and the doped substrate can be nearly the same everywhere except in the spectral vicinity of the refractive index anomaly.

[0015] For example, the diffractive interface may be a diffractive or holographic optical element, which corresponds to a wide variety of equivalent optical elements such as lenses (e.g., concave or convex lenses), gratings, polarizers, occulting masks, or any other diffractive surface configured to provide a predetermined manipulation of the optical wavefront. As an example, the diffractive interface may have a diffraction efficiency higher than a predetermined threshold (e.g., about 95%) in a region corresponding to the refractive index anomaly. The interaction of light with a surface is substantially dominated by the diffractive surface only if the dispersion differs between the surfaces.

[0016] Thus, the optical element can provide predetermined manipulation of light beams having wavelengths in that portion of the frequency spectrum and can be substantially transparent to light beams having wavelengths outside that portion of the frequency spectrum. Further, multiple separate optical elements can be implemented within the optical system, each having a refractive index anomaly associated with a separate portion of the frequency spectrum, such that different portions of the frequency spectrum of the light beam can be affected.

[0017] 1 is a diagram illustrating an example of an optical element 10. The optical element 10 may be implemented in any of a variety of optical systems capable of performing optical imaging. As described herein, the term "optical" with respect to optical systems, light beams, and / or optical imaging may refer to the manipulation of electromagnetic radiation across a very broad frequency spectrum (e.g., from below the very long wavelength infrared (VLWIR) to above the ultraviolet (UV)), and thus is not limited to the visible spectrum.

[0018] The optical element 10 includes a first optical material structure 12 and a second optical material structure 14. The first optical material structure 12 is an OPT in the example of FIG. IN As an example, the input light beam OPT has a first refractive index over a frequency spectrum associated with the input light beam, denoted as INcan have one or more wavelengths and can have an optical path through the optical element 10. The second optical material structure 14 includes a refractive index affecting impurity 16 configured to exhibit a refractive index anomaly related to the refractive index of the second optical material structure 14. The refractive index anomaly can correspond to a change in refractive index from a first refractive index to a second refractive index over a portion of the frequency spectrum, and a change from the second refractive index to the first refractive index along the frequency spectrum. Thus, as described in more detail herein, the refractive index anomaly can be used to affect the optical beam OPT based on the Christiansen effect. IN It is possible to provide a diffraction of

[0019] For example, the first optical material structure 12 and the second optical material structure 14 can each include the same substrate material (e.g., any of various types of glasses or glass oxides) so that the first optical material structure 12 and the second optical material structure 14 can exhibit the same nominal refractive index. The refractive index-affecting impurities 16 can correspond to any of a variety of materials that can be introduced into the substrate material of the second optical material structure 14 to introduce a refractive index anomaly in a predetermined portion of the frequency spectrum. For example, the refractive index-affecting impurities 16 can correspond to dopant materials, dyes, embedded nanoparticle absorbers, implanted ions, or any other type of material that is placed into the substrate material of the second optical material structure 14 to introduce a refractive index anomaly. Thus, the first optical material structure 12 and the second optical material structure 14 can exhibit approximately the same refractive index along the frequency spectrum, except for a predetermined portion of the frequency spectrum corresponding to the refractive index anomaly, where the refractive indexes of the first optical material structure 12 and the second optical material structure 14 are different. As another example, one of the optical material structures 12 and 14 may be formed from an electro-optic material to provide electro-optic control of the refractive index of the respective one of the optical material structures.

[0020] The optical element 10 also includes a diffractive interface 18 that corresponds to the contact junction of the first optical material structure 12 and the second optical material structure 14. As described herein, the diffractive interface 18 is not a physical component per se, but rather refers to the flush physical contact interface of the opposing surfaces of the first optical material structure 12 and the second optical material structure 14. For example, the diffractive interface 18 may be a lens (e.g., concave or convex), a grating, a polarizer, a diffractive optical element, a holographic optical element, or a light beam OPT. IN Diffractive interface 18 may correspond to any of a variety of geometrical and physical surfaces for providing optical manipulation of the first and second optical material structures, such as any other diffractive surface configured to provide a predetermined diffraction of . Thus, diffractive interface 18 corresponds to a non-planar material contact junction associated with a surface of second optical material structure 14 and a complementary surface of first optical material structure 12.

[0021] As an example, the diffractive interface 18 can be fabricated based on physical optics to have a diffraction efficiency greater than a predetermined threshold in a portion of the frequency spectrum that approximately corresponds to the portion of the frequency spectrum of the refractive index anomaly. Thus, the diffractive interface 18 can be configured to diffract light beams OPT having wavelengths that lie in the predetermined portion of the frequency spectrum. IN The output light beam OPT is configured to be manipulated in a predetermined manner. As used herein, the term "manipulating a light beam" refers to any of a variety of diffraction-related manipulations, such as focusing (e.g., as a lens), directing, polarizing, filtering, or any other type of optical manipulation. Thus, the output light beam OPT OUT is the output light beam OPT OUT OPT of a light beam at a wavelength in that portion of the frequency spectrum based on a combination of refractive index anomalies and diffractive interfaces 18. IN may be provided at the output of the optical element 10 so as to be able to show the optical operation of

[0022] 2 is a diagram illustrating another example of an optical element 50. The optical element 50 can be implemented in any of a variety of optical systems capable of performing optical imaging. The optical element 50 is shown in the example of FIG. 2 as a diagram of the optical element 10 in the example of FIG. 1. Accordingly, in the following description of the example of FIG. 2, reference is made to the example of FIG. 1.

[0023] The optical element 50 includes a first optical material structure 52 and a second optical material structure 54. The first optical material structure 52 is configured to receive an input light beam OPT. IN The second optical material structure 54 has a first refractive index over a frequency spectrum associated with the first optical material structure 54. The second optical material structure 54 is shown shaded in the example of FIG. 2 to indicate the inclusion of refractive index affecting impurities configured to exhibit a refractive index anomaly associated with the refractive index of the second optical material structure 54.

[0024] For example, the first optical material structure 52 and the second optical material structure 54 may each include the same substrate material such that the first optical material structure 52 and the second optical material structure 54 may exhibit the same nominal refractive index. Thus, impurities that affect the refractive index may introduce a refractive index anomaly in a predetermined portion of the frequency spectrum. Thus, the first optical material structure 52 and the second optical material structure 54 may exhibit approximately the same refractive index along the frequency spectrum, except for a predetermined portion of the frequency spectrum corresponding to the refractive index anomaly, where the refractive indexes of the first optical material structure 52 and the second optical material structure 54 are different.

[0025] The optical element 50 also includes a diffractive interface 56 corresponding to the contact junction of the first optical material structure 52 and the second optical material structure 54. In the example of FIG. 2, the diffractive index 58 is shown as a grating etched on a surface of one of the first optical material structure 52 and the second optical material structure 54. As an example, the other of the first optical material structure 52 and the second optical material structure 54 can be applied to the etched surface, such as via a melting or sputtering process, to provide a complementary surface of the other of the first optical material structure 52 and the second optical material structure 54 to provide the diffractive interface 56. However, alternative methods can be provided to provide flush contact between the first optical material structure 52 and the second optical material structure 54 to form the diffractive interface 56 between the first optical material structure 52 and the second optical material structure 54.

[0026] As an example, the diffractive interface 56 can be fabricated to have a diffraction efficiency greater than a predetermined threshold (e.g., about 95%) in a portion of the frequency spectrum that approximately corresponds to a portion of the frequency spectrum of the refractive index anomaly. As an example, fabrication of the diffractive interface 56 can include providing physical characteristics of the diffractive interface 56 (e.g., relating to dimensions of the grating or other physical aspects of the diffractive interface 56) that affect a particular band of the frequency spectrum, the particular band approximately corresponding to the portion of the frequency spectrum of the refractive index anomaly. As an example, the diffractive interface 56 can be fabricated to have a diffraction efficiency greater than a predetermined threshold (e.g., about 95%) in a portion of the frequency spectrum that approximately corresponds to a portion of the frequency spectrum of the refractive index anomaly. I The diffraction grating can be patterned to provide a diffractive bandpass Δλ starting from

[0027]

number

[0028] Here, PT corresponds to a predetermined threshold value of the diffraction efficiency. For example, the diffractive interface 56 may be patterned in a predetermined manner on a surface of one of the first and second optical material structures 52, 54 to provide a diffraction efficiency above a predetermined threshold at a location on the frequency spectrum approximately equal to a predetermined portion of the frequency spectrum of the refractive index anomaly. As another example, a refractive index affecting impurity may be introduced in a predetermined manner into the second optical material structure 54 to exhibit a refractive index anomaly at a location on the frequency spectrum approximately equal to a predetermined portion of the frequency spectrum where the diffraction efficiency of the diffractive interface 56 is greater than a predetermined threshold.

[0029] Thus, the diffractive interface 56 transmits a beam of light OPT having a wavelength that lies in a predetermined portion of the frequency spectrum. IN , which is configured to manipulate the output light beam OPT in a predetermined manner. OUT is the output light beam OPT OUT OPT of a light beam at a wavelength in that portion of the frequency spectrum based on a combination of refractive index anomalies and diffractive interfaces 56. IN may be provided at the output of the optical element 50 so as to be able to show the optical operation of

[0030] As a result, the optical element 50 can be configured to correct any of a variety of optical aberrations in an optical system, such as spherical aberration and / or chromatic aberration, or to correct the light beam OPT IN The optical element 50 can be implemented to provide selective polarization, filtering, or redirection of a portion of the wavelengths in the frequency band. In addition, the optical element 50 has spectral selectivity with respect to a portion of the frequency band, and is transparent to all other wavelengths in the frequency spectrum. Thus, the optical element 50 can be included in an optical system to correct wavelengths in that portion of the frequency band without adversely affecting other portions of the frequency band, as is typical when a typical optical system includes other types of corrective optics. Furthermore, because the optical element 50 is formed from only two substrate material structures, the optical element 50 is significantly smaller and lighter than typical optical correction devices.

[0031] Figure 3 is a diagram 100 illustrating an example of a refractive index graph, generally indicated at 102, and a diffraction efficiency graph, generally indicated at 104, of an optical element. By way of example, the refractive index graph 102 and the diffraction efficiency graph 104 may correspond to the optical element 10 and / or the optical element 50 in the examples of Figures 1 and 2, respectively. Accordingly, the following example of Figure 3 refers to the examples of Figures 1 and 2.

[0032] Diagram 100 shows a frequency spectrum plotted against wavelength λ, along which a refractive index graph 102 and a diffraction efficiency graph 104 are plotted. The frequency spectrum λ starts at a wavelength λ0 corresponding to the longest wavelength on the frequency spectrum λ, and increases in frequency / decreases in wavelength. The refractive index graph 102 shows the refractive index of each of the first optical material structure 52 and the second optical material structure 54, with the refractive index of the first optical material structure 52 shown as a solid line and the refractive index of the second optical material structure 54 shown as a dashed line. Starting at wavelength λ0, the refractive indexes of the respective first optical material structure 52 and second optical material structure 54 are approximately equal and decrease from an initial value to a nominal value "A".

[0033] At wavelength λ1, the refractive index of the second optical material structure 54 increases relative to the refractive index of the first optical material structure 52. The difference in refractive index between the first optical material structure 52 and the second optical material structure 54 can be based on the introduction of a refractive index anomaly, indicated at 106 in the example of FIG. 3, in the second optical material structure 54 due to an impurity that affects the refractive index. Thus, even though the first optical material structure 52 and the second optical material structure 54 are fabricated from the same substrate material, the second optical material structure 54 can have a different refractive index in a portion of the frequency spectrum λ relative to the first optical material structure 52 due to the impurity that affects the refractive index. As a result, the light beam OPT INcan undergo the Christiansen effect in the portion of the frequency spectrum λ corresponding to the refractive index anomaly 106. The refractive index of the second optical material structure 54 is shown to increase to a maximum value "B" and then decrease back to approximately value "A" at wavelength λ4. The refractive index of the first optical material structure 52 remains approximately constant between wavelengths λ1 and λ4. At frequencies greater than wavelength λ4, and therefore wavelengths less than wavelength λ4, the refractive indices of the first optical material structure 52 and the second optical material structure 54 are approximately the same.

[0034] As previously mentioned, the diffractive interface 56 may be patterned to provide a diffraction efficiency for a portion of the frequency spectrum λ that is greater than a predetermined threshold. In the example of FIG. 3, the diffractive interface 56 may be fabricated in a predetermined manner to provide a diffraction efficiency for a portion of the frequency spectrum λ that is greater than a predetermined threshold, shown in the example of FIG. 3 as about 95%. In the example of FIG. 3, the portion of the frequency spectrum λ in which the diffraction efficiency is greater than about 95% is between wavelengths λ2 and λ3, thus defining a diffraction bandpass Δλ of the diffractive interface 56. As an example, the diffractive interface 56 may be fabricated such that the diffraction bandpass Δλ is approximately centered on the refractive index anomaly 106. As a result, the diffractive interface 56 and the refractive index anomaly 106 cooperate to provide a light beam OPT within the diffraction bandpass Δλ. IN Manipulate the wavelength of.

[0035] As mentioned above, the optical element 50 may correspond to one of multiple optical elements in an optical system. As an example, multiple optical elements 50 may be implemented in an optical system to affect multiple different portions of a frequency band, e.g., to correct optical aberrations in different portions of the frequency band. Thus, multiple optical elements 50 may be implemented along a given optical path to affect respective multiple different portions of the frequency spectrum λ.

[0036] 4 illustrates an example diagram 150 of an optical system 152 and a corresponding graph of refractive index, generally indicated at 154, and diffraction efficiency, generally indicated at 156. The optical system 152 may be implemented in any of a variety of optical imaging environments. In the example of FIG. 4, the optical system 152 includes an input light beam OPT IN In the optical path of the optical fiber 100, a first optical element 158 ​​and a second optical element 160 are included. As described herein, the optical elements 158 and 160 can provide selective optical manipulation for distinct respective portions of the frequency spectrum λ.

[0037] The optical element 158 ​​includes a first optical material structure 162 and a second optical material structure 164. The first optical material structure 162 has a first refractive index across the frequency spectrum λ. The second optical material structure 164 is shown shaded in the example of FIG. 4 to indicate the inclusion of refractive index-affecting impurities configured to exhibit a refractive index anomaly, shown at 166 in the graph 154, associated with the refractive index of the second optical material structure 164. The optical element 158 ​​also includes a diffractive interface 168 corresponding to the contact junction of the first optical material structure 162 and the second optical material structure 164. The diffractive interface 168 can have a diffractive bandpass Δλ1 that substantially matches the refractive index anomaly 166. Thus, the optical element 158 ​​is arranged substantially similarly to the optical element 50 in the example of FIG. 2. The first optical element 158 ​​may be configured to OPTIMIZE the input light beam, such as based on optical manipulation of wavelengths within the diffractive bandpass Δλ1 that substantially matches the refractive index anomaly 166. IN Intermediate light beam OPT based on PTH can be provided.

[0038] Similarly, the optical element 160 includes a first optical material structure 168 and a second optical material structure 170. The first optical material structure 168 has a first refractive index across the frequency spectrum λ. The second optical material structure 170 is shown shaded in the example of FIG. 4 to indicate the inclusion of a refractive index-affecting impurity configured to exhibit a refractive index anomaly, shown at 172 in the graph 154, associated with the refractive index of the second optical material structure 170. As an example, the refractive index-affecting impurity in the second optical material structure 170 may be different from the refractive index-affecting impurity in the second optical material structure 164 to provide the refractive index anomaly 172 at a different portion of the frequency spectrum λ. The optical element 160 also includes a diffractive interface 174 corresponding to the contact junction of the first optical material structure 168 and the second optical material structure 170. The diffractive interface 174 may have a diffractive bandpass Δλ2 that substantially matches the refractive index anomaly 172. As an example, the physical characteristics of the diffractive interfaces 168 and 174 can be substantially different such that they result in a diffractive bandpass Δλ1 that is different from the diffractive bandpass Δλ2, and thus the diffractive bandpasses Δλ1 and Δλ2 do not overlap. Thus, the optical element 160 is arranged substantially similarly to the optical element 50 in the example of FIG. 2. The second optical element 160 is arranged to OPTIMIZE the intermediate light beam, such as based on optical manipulation of wavelengths within the diffractive bandpass Δλ2 that substantially matches the refractive index anomaly 172. PTH Output light beam based on OPT OUT can be provided.

[0039] As before, diagram 150 shows a graph 162 of refractive index and a graph 164 of diffraction efficiency plotted against a frequency spectrum λ. The frequency spectrum λ starts at a wavelength λ0 corresponding to the longest wavelength on the frequency spectrum λ and increases in frequency / decreases in wavelength. The graph of refractive index 162 shows the refractive index of each of optical material structures 162 and 164 and optical material structures 168 and 170, with the refractive index of optical material structures 162 and 168 corresponding to the nominal refractive index of the substrate material of optical material structures 162, 164, 168, and 170 shown as a solid line, the refractive index of optical material structure 164 shown as a dashed line, and the refractive index of optical material structure 170 shown as a dotted line. Starting at wavelength λ0, the refractive index of each of optical material structures 162, 164, 168, and 170 is approximately equal and decreases from an initial value to a nominal value "A".

[0040] At wavelength λ1, the refractive index of the optical material structure 164 increases relative to the refractive index of the optical material structures 162, 168, and 170. The difference in refractive index between the optical material structure 164 and the optical material structures 162, 168, and 170 can be based on the introduction of a refractive index anomaly 166. The refractive index of the optical material structure 164 is shown to increase to a maximum value "B" and then decrease back to approximately value "A" at wavelength λ4. The refractive index of the optical material structures 162, 168, and 170 remains approximately constant between wavelengths λ1 and λ4. At wavelength λ5, the refractive index of the optical material structure 170 increases relative to the refractive index of the optical material structures 162, 164, and 168. The difference in refractive index between the optical material structure 170 and the optical material structures 162, 164, and 168 can be based on the introduction of a refractive index anomaly 172. The refractive index of optical material structure 170 is shown to increase to a maximum value "B" and then decrease back to approximately value "A" at wavelength λ8. The refractive index of optical material structures 162, 164, and 168 remains approximately constant between wavelengths λ5 and λ8. It should be understood that the increase in refractive index is not limited to being equal (e.g., a maximum value "B") for each of refractive index anomalies 166 and 172, but can be different values ​​based on different impurities that affect the refractive index.

[0041] As previously mentioned, diffractive interfaces 168 and 174 may each be patterned to provide a respective diffraction efficiency for a respective portion of frequency spectrum λ that is greater than a predetermined threshold. In the example of Figure 4, diffractive interfaces 168 and 174 may each be fabricated in a respective predetermined manner to provide, for a distinct respective portion of frequency spectrum λ, a diffraction efficiency that is greater than a predetermined threshold, shown in the example of Figure 4 as about 95%.

[0042] In the example of FIG. 4 , the portion of the frequency spectrum λ where the diffraction efficiency of the diffractive interface 168 is greater than about 95% is between wavelengths λ2 and λ3, thus defining a diffraction bandpass Δλ1 of the diffractive interface 168. Similarly, the portion of the frequency spectrum λ where the diffraction efficiency of the diffractive interface 174 is greater than about 95% is between wavelengths λ6 and λ7, thus defining a diffraction bandpass Δλ2 of the diffractive interface 174. As an example, the diffractive interface 168 may be fabricated such that the diffraction bandpass Δλ1 is approximately centered on the refractive index anomaly 166, and the diffractive interface 174 may be fabricated such that the diffraction bandpass Δλ2 is approximately centered on the refractive index anomaly 174. As a result, the diffractive interface 168 and the refractive index anomaly 166 cooperate to diffract the light beam OPT within the diffraction bandpass Δλ1. IN The diffractive interface 174 and the refractive index anomaly 172 cooperate to OPT the optical beam within the diffractive bandpass Δλ PTH Manipulate the wavelength of.

[0043] The optical system 152 is not limited to only the two optical elements 154 and 156, but may include one or more additional optical elements, each associated with a separate portion of the frequency spectrum λ, and associated with one or more separate optical paths of the optical system. Thus, multiple spectral aberrations may be selectively corrected and / or introduced in each associated optical system. Thus, the optical elements described herein may be flexibly implemented to provide desired optical results across the frequency spectrum λ.

[0044] In view of the structural and functional features discussed above, methods according to various aspects of exemplary embodiments will be better understood with reference to Figure 5. For purposes of simplicity of explanation, the method of Figure 5 is shown and described as being performed sequentially, however, it should be understood and appreciated that exemplary embodiments are not limited by the order shown, as some aspects may occur in a different order and / or simultaneously with other aspects in accordance with exemplary embodiments than as shown and described herein. Moreover, not all illustrated features are required to implement a method according to an aspect of an exemplary embodiment.

[0045] FIG. 5 illustrates an example of a method 200 for manufacturing an optical element (e.g., optical element 10). At 202, a first optical material structure (e.g., first optical material structure 12) formed from a substrate material and having a first refractive index across a frequency spectrum (e.g., frequency spectrum λ) is provided. At 204, a second optical material structure (e.g., second optical material structure 14) formed from the substrate material is provided. At 206, a refractive index-affecting impurity (e.g., refractive index-affecting impurity 16) is introduced into the second optical material structure to facilitate the development of a refractive index change from the first refractive index to the second refractive index across a portion of the frequency spectrum and a refractive index anomaly (e.g., refractive index anomaly 106) corresponding to the change from the second refractive index to the first refractive index along the frequency spectrum. At 208, an optical diffraction structure is formed on one surface of the first and second optical material structures. At 210, a complementary structure is formed on the other surface of the first and second optical material structures. At 212, the first and second optical material structures are bonded via surfaces of the first and second optical material structures to form a diffractive interface (e.g., diffractive interface 18) between the first and second optical material structures.

[0046] The above is an example of the present disclosure. Of course, it is not possible to describe every conceivable combination of components or methods for purposes of describing the present disclosure, but one skilled in the art will recognize that many further combinations and permutations of the present disclosure are possible. Therefore, the present disclosure is intended to encompass all such changes, modifications, and variations that fall within the scope of this application, including the appended claims. Furthermore, when a disclosure or claim describes "a, an," "a first," "another" element, or the equivalent thereof, it should be construed as including one or more such elements, and does not require or exclude two or more such elements. As used herein, the term "includes, including" means including without limitation. The term "based on" means based at least in part on.

Claims

1. An optical element, a first optical material structure having a first refractive index across a frequency spectrum; a second optical material structure configured to exhibit a refractive index anomaly corresponding to a change in refractive index from the first refractive index to a second refractive index across a portion of the frequency spectrum and a change from the second refractive index to the first refractive index along the frequency spectrum; a diffractive interface corresponding to a non-planar material contact junction between the first optical material structure and the second optical material structure; and the diffractive interface being configured to steer in a predetermined manner a beam of light having an optical path through the diffractive interface and having a frequency in the portion of the frequency spectrum.

2. 2. The element of claim 1, wherein the first optical material structure and the second optical material structure each comprise the same substrate material, and the second optical material structure comprises a refractive index-affecting impurity configured to facilitate the manifestation of the refractive index anomaly for the second optical material structure.

3. The device of claim 2 , wherein the refractive index affecting impurity is a dopant material introduced into the substrate material of the second optical material structure.

4. The element of claim 2 , wherein the refractive index affecting impurity is a dye introduced into the substrate material of the second optical material structure.

5. The device of claim 2 , wherein the refractive index affecting impurity is an ion implant introduced into the substrate material of the second optical material structure.

6. 2. The element of claim 1, wherein the diffractive interface corresponds to a light control structure patterned on a surface of one of the first optical material structure and the second optical material structure and a complementary light control structure patterned on an opposing surface of the other of the first optical material structure and the second optical material structure.

7. The element of claim 1 , wherein the diffractive interface corresponds to one of a diffractive optical element, a holographic optical element, a polarizer, or a lens.

8. The element of claim 1 , wherein the diffraction index is designed to provide a diffraction efficiency greater than a predetermined threshold over a diffraction bandpass that is approximately the same as the portion of the frequency spectrum.

9. The element of claim 8 , wherein the predetermined threshold value of diffraction efficiency is greater than or equal to about 95%.

10. 10. An optical system comprising the optical element of claim 1, wherein the optical element is a first optical element, the optical system further comprising a second optical element in the optical path of the light beam.

11. The second optical element is a third optical material structure having the first refractive index across the frequency spectrum; and a fourth optical material structure configured to exhibit a change in refractive index from the first refractive index to a third refractive index over a second portion of the frequency spectrum, and a second refractive index anomaly corresponding to the change from the third refractive index to the first refractive index along the frequency spectrum; and a second diffractive interface corresponding to a second non-planar material contact junction between the third optical material structure and the fourth optical material structure; and 11. The optical system of claim 10, comprising: the second diffractive interface configured to steer in a predetermined manner the light beam having the light path through the second diffractive interface and having a frequency in the second portion of the frequency spectrum.

12. The element of claim 1 , wherein the diffractive interface is a blocking mask.

13. The element of claim 1 , wherein the diffractive interface comprises a structured anti-reflective coating.

14. The device of claim 1 , wherein a substrate material of the second optical material structure is formed from an electro-optic material to provide electro-optic control of the second refractive index.

15. The element of claim 1 , wherein the diffractive interface is defined by a physical optical system for manipulating the light beam in the predetermined manner.

16. 1. A method for manufacturing an optical element, comprising the steps of: providing a first optical material structure formed from a substrate material and having a first refractive index across a frequency spectrum; providing a second optical material structure formed from the substrate material; introducing a refractive index affecting impurity into the second optical material structure to facilitate the development of a refractive index anomaly corresponding to a change in refractive index from the first refractive index to a second refractive index across a portion of the frequency spectrum and from the second refractive index to the first refractive index along the frequency spectrum; forming an optical diffractive structure on a surface of one of the first optical material structure and the second optical material structure; forming a complementary structure on a surface of the other of the first optical material structure and the second optical material structure; bonding the first optical material structure and the second optical material structure via the surfaces of the first optical material structure and the second optical material structure to form a diffractive interface between the first optical material structure and the second optical material structure; wherein the diffractive interface is configured to steer in a predetermined manner a beam of light having an optical path through the diffractive interface and having a frequency in the portion of the frequency spectrum.

17. 17. The method of claim 16, wherein introducing the refractive index affecting impurity comprises doping the substrate material of the second optical material structure with the refractive index affecting impurity.

18. 17. The method of claim 16, wherein forming the optical diffractive structure comprises etching one of a diffractive optical element, a holographic optical element, a polarizer, or an optical grating onto the surface of the second optical material structure.

19. 17. The method of claim 16, wherein forming the complementary structure comprises sputtering the other of the first and second optical material structures onto the optical diffraction structure on the surface of the given one of the first and second optical material structures.

20. 17. The method of claim 16, wherein forming the optical diffractive structure includes forming the optical diffractive structure to provide a diffraction efficiency greater than a predetermined threshold over a second portion of the frequency spectrum defining a diffraction bandpass of the diffractive interface, the method further including matching the diffraction bandpass to a first portion of the frequency spectrum.

21. a first optical element in the path of the light beam, a first optical material structure having a first refractive index across a frequency spectrum; a second optical material structure configured to exhibit a change in refractive index from the first refractive index to a second refractive index across a first portion of the frequency spectrum, and a first refractive index anomaly corresponding to the change from the second refractive index to the first refractive index along the frequency spectrum; a first diffractive interface corresponding to a first non-planar material contact junction between the first optical material structure and the second optical material structure, the first diffractive interface being configured to manipulate in a predetermined manner the light beam having a frequency in the first portion of the frequency spectrum; A first optical element comprising: a second optical element in the optical path of the light beam, a third optical material structure having the first refractive index across the frequency spectrum; and a fourth optical material structure configured to exhibit a change in refractive index from the first refractive index to a third refractive index over a second portion of the frequency spectrum, and a second refractive index anomaly corresponding to the change from the third refractive index to the first refractive index along the frequency spectrum; and a second diffractive interface corresponding to a second non-planar material contact junction between the third optical material structure and the fourth optical material structure, the second diffractive interface being configured to manipulate in a predetermined manner the light beam having a frequency in the second portion of the frequency spectrum; A second optical element comprising: An optical system comprising:

22. 22. The system of claim 21, wherein the first optical material structure and the second optical material structure each comprise a first same substrate material, the third optical material structure and the fourth optical material structure each comprise a second same substrate material, the second optical material structure comprises a first refractive index-affecting impurity configured to facilitate the manifestation of the refractive index anomaly for the second optical material structure, and the fourth optical material structure comprises a second refractive index-affecting impurity configured to facilitate the manifestation of the refractive index anomaly for the fourth optical material structure.

23. 22. The element of claim 21, wherein the first diffractive interface corresponds to a first light control structure patterned on a surface of one of the first optical material structure and the second optical material structure and a complementary light control structure patterned on an opposing surface of the other of the first optical material structure and the second optical material structure, and the second diffractive interface corresponds to a second light control structure patterned on a surface of one of the third optical material structure and the fourth optical material structure and a complementary light control structure patterned on the opposing surface of the other of the third optical material structure and the fourth optical material structure.

24. 22. The system of claim 21 , wherein the first diffraction index is designed to provide a diffraction efficiency greater than a first predetermined threshold over a first diffraction bandpass that is approximately the same as the first portion of the frequency spectrum, and the second diffraction index is designed to provide a diffraction efficiency greater than a second predetermined threshold over a second diffraction bandpass that is approximately the same as the second portion of the frequency spectrum.

25. An optical element, a first optical substrate having a predetermined refractive index dispersion curve over a first transmission spectral range; a second optical substrate exhibiting a refractive index anomaly relative to the first substrate over a second transmission spectral range within the first transmission spectral range, the second optical substrate having approximately the same dispersion as the first optical substrate outside the second transmission spectral range; a complementary geometric beam control interface between the first optical substrate and the second optical substrate corresponding to a non-planar material contact junction between the first optical material structure and the second optical material structure; wherein the complementary geometric beam control interfaces are configured to steer in a predetermined manner a beam of light having an optical path through the interfaces.

26. 26. The element of claim 25, wherein the optical element comprises a plurality of optical substrate pairs with a respective plurality of complementary geometric beam control interfaces therebetween, and the second transmission spectral range associated with each of the plurality of optical substrate pairs does not overlap with the second transmission spectral range of each other optical substrate pair of the plurality of optical substrate pairs.

27. The element of claim 2 , wherein the refractive index affecting impurities are spectrally absorbing nanoparticles, the density of which determines the spectral absorptivity of the material.

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