Inducing morphological changes and nanopatterning in a substrate using near-field focusing of ultrafast laser

Abstract

A method may include directing an ultrafast laser beam onto the surface of a substrate coated with dielectric microparticles such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

Description

[0001] ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0002] 1

[0003] INDUCING MORPHOLOGICAL CHANGES AND NANOPATTERNING IN A SUBSTRATE USING NEAR-FIELD FOCUSING OF ULTRAFAST LASER

[0004] STATEMENT OF GOVERNMENT SUPPORT

[0005] This invention was made with government support under Grant no. W911NF- 22-1-0124 awarded by the Army Research Office. The government has certain rights in the invention.

[0006] RELATED APPLICATION

[0007] This application claims priority to United States Provisional Patent Application Serial No. 63 / 651,659, filed May 24, 2024, which is incorporated by reference herein in its entirety.

[0008] FIELD OF DISCLOSURE

[0009] The present disclosure relates in general to systems and methods for inducing morphological changes and direct material removal in a substrate, such as a sapphire substrate, using near-field focusing of an ultrafast laser. The material with the modified morphology may be removed using subsequent etching processes, resulting in surface and sub-surface structures in the substrates.

[0010] 45102500v.1 ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0011] 2

[0012] BACKGROUND

[0013] The creation of nanostructures on a substrate, such as a sapphire substrate, may have uses in many fields, including without limitation optoelectronics, photonics, and sensing. Sapphire exhibits attractive properties including high mechanical hardness, broad optical transparency spectrum, and excellent chemical inertness, making the material useful for photonic, optoelectronic, and transparent ceramic applications. Many of these uses stand to benefit from surface functionalization via nanostructures, which can exhibit anti-glare, self-cleaning, and anti-fogging properties. Surface functionalization has been extensively demonstrated in conventional optics materials such as silica-based glass, using well established nanofabrication processes.

[0014] Unfortunately, the higher hardness and chemical stability of sapphire, for which the material is prized, preclude the effectiveness of many conventional nanomachining processes. Existing approaches have enabled patterning and formation of periodic arrays of nanostructures in sapphire using a multilayer mask in conjunction with dry -etching processes or by inducing morphology7changes using an ultrafast laser direct-writing process with subsequent selective etching. Both techniques have been used to create sapphire surfaces that exhibit useful optical, wetting, and other properties. However, the multitude of complex deposition and etch steps inherent to multilayer masks and the serial nature of ultrafast laser direct-write processes result in low throughput that constrains scalability.

[0015] However, it may be desirable to achieve sapphire nanostructures with smaller features and higher etch depth than those obtainable using traditional approaches, to enable greater density7of nanostructures. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0016] 3

[0017] SUMMARY

[0018] In accordance with the teachings of the present disclosure, the disadvantages and problems associated with existing approaches to forming nanostructures on sapphire or other material substrates may be reduced or eliminated.

[0019] In accordance with embodiments of the present disclosure, a method may include directing an ultrafast laser beam onto the surface of a substrate coated with dielectric microparticles such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

[0020] In accordance with these and other embodiments of the present disclosure, a system may include a first subsystem configured to coat a surface of a substrate with dielectric microparticles, a second subsystem configured to direct an ultrafast laser beam onto the surface of the substrate such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate, and a third subsystem configured to etch the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

[0021] In accordance with these and other embodiments of the present disclosure, a method for preparing a substrate for creation of nanostructures upon a surface of the substrate may include coating the surface of the substrate with dielectric microparticles.

[0022] In accordance with these and other embodiments of the present disclosure, a method may include arranging a dielectric phase mask comprising microstructures and / or nanostructures such that the microstructures and / or nanostructures are proximate to the surface of a substrate, directing an ultrafast laser beam through the dielectric phase mask and to a surface of the substrate such that the microstructures ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0023] 4 and / or nanostructures serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate, and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

[0024] In accordance with these and other embodiments of the present disclosure, an apparatus may include a substrate and nanostructures formed on the surface of the substrate by directing an ultrafast laser beam onto the surface of a substrate coated with dielectric microparticles such that the dielectric microparticles serve as lenses to focus photonic nanoj ets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate which are removed via etching.

[0025] Technical advantages of the present disclosure may be readily apparent to one having ordinary skill in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims.

[0026] It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure.

[0027] ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0028] 5

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawing, in which like reference numbers indicate like features, and wherein:

[0031] FIGURE 1 illustrates a cross-sectional elevation view of an example system for patterning nanostructures on a surface of a material substrate, in accordance with embodiments of the present disclosure;

[0032] FIGURE 2 illustrates a flow chart for an example method of inducing morphological changes in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure;

[0033] FIGURE 3 illustrates a cross-sectional elevation view of a processing step for inducing morphological changes in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure;

[0034] FIGURE 4 illustrates a cross-sectional elevation view of another processing step for inducing morphological changes in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure;

[0035] FIGURE 5 illustrates a cross-sectional elevation view of a further processing step for inducing morphological changes in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure;

[0036] FIGURE 6 illustrates a cross-sectional elevation view of an additional processing step for inducing morphological changes in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure;

[0037] FIGURE 7 illustrates a cross-sectional elevation view of yet another additional processing step for removing the region with the modified morphology in a substrate using near-field focusing of an ultrafast laser, in accordance with embodiments of the present disclosure; ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0038] 6

[0039] FIGURE 8 illustrates a large-area approach to ultrafast laser exposure, in accordance with embodiments of the present disclosure;

[0040] FIGURE 9 illustrates a direct-write approach to ultrafast laser exposure, in accordance with embodiments of the present disclosure; FIGURES 10A-10E illustrate a multiple exposure with angled exposures approach to ultrafast laser exposure, in accordance with embodiments of the present disclosure;

[0041] FIGURE 11 illustrates a varying angle, continuous exposure approach to ultrafast laser exposure, in accordance with embodiments of the present disclosure; and

[0042] FIGURES 12A-12D illustrate an approach to ultrafast laser exposure involving a dielectric phase mask with microstructures and / or nanostructures used in lieu of microspheres, in accordance with embodiments of the present disclosure.

[0043] ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0044] 7

[0045] DETAILED DESCRIPTION

[0046] FIGURE 1 illustrates a cross-sectional elevation view of an example system 100 for patterning nanostructures on a surface of a material substrate 110, in accordance with embodiments of the present disclosure. As shown in FIGURE 1. system 100 may include an illumination source 102, a lens 104, a stage 106, and a control system 108.

[0047] Illumination source 102 may comprise any suitable system, device, or apparatus configured to generate electromagnetic energy in the form of visible or invisible light. In some embodiments, illumination source 102 may comprise a laser configured to generate a collimated beam of light at one or more desired wavelengths. In these and other embodiments, illumination source 102 may be configured to direct electromagnetic energy generated by illumination source 102 towards stage 106.

[0048] Lens 104 may comprise an optical transparent piece of material, usually glass or plastic, with curved surfaces that refract light in order to converge or diverge light. For example, lens 104 may converge light from illumination source 102 to focus such light onto substrate 110. In some embodiments, lens 104 may be optional. In some embodiments, light from illumination source 102 onto a substrate may be collimated (normal to surface of substrate 1 10) or focused. In some embodiments, a curved mirror or micro-mirror array may also be used to focus light.

[0049] Stage 106 may comprise any suitable system, device, or apparatus configured to carry or otherwise hold and position substrate 110. In some embodiments, one or both of illumination source 102 and stage 106 may comprise or may be coupled to a motor or other device configured to vertically or horizontally translate illumination source 102 and / or stage 106 relative to one another, in order to enable light generated by illumination source 102 to impinge upon desired locations upon the surface of substrate 110.

[0050] Control system 108 may comprise any suitable system, device, or apparatus configured to control operation of illumination source 102 and stage 106, including without limitation an intensity of electromagnetic energy generated by illumination ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0051] 8 source 102, a pulse duration of electromagnetic energy generated by illumination source 102, a position of illumination source 102, and / or a position of stage 106. For example, in some embodiments, control system 108 may comprise a computing system.

[0052] Substrate 1 10 may comprise any suitable piece of material. In some embodiments, substrate 110 may comprise a crystalline material. In such embodiments, substrate 110 may comprise a single-cry stal material. In particular embodiments, substrate 110 may comprise sapphire (e.g., single-crystal sapphire). In other embodiments, substrate 1 10 may comprise aluminium oxynitride (Al ON), magnesium aluminate spinel (MgAhO4), yttrium aluminum garnet (YAG), or a hard ceramic.

[0053] In operation, system 100 may be used to induce morphological changes in a substrate using near-field focusing of an ultrafast laser, as described in greater detail below.

[0054] FIGURE 2 illustrates a flow chart for an example method 200 of inducing morphological changes in substrate 110 using near-field focusing of an ultrafast laser (e.g., from illumination source 102). According to some embodiments, method 200 may begin at step 202. As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system 100. As such, the preferred initialization point for method 200 and the order of the steps comprising method 200 may depend on the implementation chosen.

[0055] At step 202, dielectric microspheres 302 may be coated on a surface of substrate 110, as shown in FIGURE 3. Dielectric microspheres 304 may be coated on the surface of substrate 110 using any suitable approach, including without limitation drop casting, spin coating, Langmuir-Blodgett assembly, and spraying onto substrate 110. Dieletric microspheres 302 may comprise any suitable material and have any shape suitable for serving as lenses to further form tightly focused laser beams (from illumination generated by illumination source 102) on the surface of substrate 110, to exploit a phenomenon known as the photonic nanojet effect. For example, in some ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0056] 9 embodiments, dielectric microspheres 302 may comprise polystyrene particles approximately 10 pm in diameter. In other embodiments, dielectric microspheres 302 may comprise silica particles ranging in size from approximately 200 nm and 200 pm in diameter (e.g., approximately 9 pm. approximately 4.3 pm, and / or approximately 1.18 pm in diameter).

[0057] At step 204, illumination source 102 may generate an ultrafast (e.g., having a pulse width of approximately 35 fs to approximately 120 fs) laser beam 402 directed onto the surface of substrate 110, for a period of time as shown in FIGURE 4. Exploiting the photonic nanojet effect, photonic nanojets may ablate or alter the crystallinity of substrate 110 to modified regions 502 of amorphous and / or poly crystalline form on the surface of substrate 110, as shown in FIGURE 5. In some embodiments, the ultrafast laser generated by illumination source 102 may have a wavelength of approximately 800 nm.

[0058] At step 206, the coating of dieletric microspheres 302 may be removed from the surface of substrate 110, as shown in FIGURE 6. For example, the coating of dieletric microspheres 302 may be removed from the surface of substrate 110 by rinsing in deionized water in an ultrasonic bath, or other suitable manner.

[0059] At step 208, a chemical or plasma etch may be applied to remove modified regions 502 (in addition to some material of substrate 110 that may be ablated by the illumination exposure itself), forming nanostructures 702 on the surface of substrate 110. as shown in FIGURE 7. Such nanostructures 702 may have a concave profile, as shown in FIGURE 7. For example, in embodiments in which substrate 1 10 comprises sapphire, hydrogen fluoride (also known as hydrofluoric acid) may be used to remove modified regions 502 of amorphous and / or polycrystalline sapphire. After step 208, method 200 may end.

[0060] Although FIGURE 2 discloses a particular number of steps to be taken with respect to method 200, method 200 may be executed with greater or fewer steps than those depicted in FIGURE 2. In addition, although FIGURE 2 discloses a certain order of steps to be taken with respect to method 200, the steps comprising method 200 may ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0061] 10 be completed in any suitable order. Method 200 may be implemented in whole or part using system 100 and / or any other system operable to implement method 200.

[0062] In some embodiments, non-spherical dielectric microparticles may be used in lieu of microspheres 302.

[0063] Any suitable approach to ultrafast laser exposure may be used. For example, in some embodiments, large-area exposure may be conducted by placing substrate 110 directly under ultrafast laser beam 402 (e g., without the presence of lens 104), as shown in FIGURE 8. In such approach, the laser may have a power of approximately 6 W and a diameter of approximately 10mm. In other embodiments, a direct-write approach may be used in which substrate 110 may be placed under lens 104, and large- area exposure may be achieved by moving laser beam 402 across the surface of substrate 110. as shown in FIGURE 9. In such approach, the laser power may be limited to approximately 1 W. and the beam diameter may depend on the defocus length of lens 104.

[0064] In yet other embodiments, a multiple exposure with angled exposures approach may be used, in which substrate 110 may be placed under lens 104, and multiple exposures 402 A, 402B, and 402C of laser beam 402 may be made, each at a different angle relative to the surface of substrate 1 1 , as shown in FIGURES 10A-10E. For example, a first exposure at 90 degrees relative to the surface of substrate 110 (as shown in FIGURE 10B) may generate a first set of modified regions 502A (as show n in FIGURE 10C). a second exposure at a non-normal angle relative to the surface of substrate 110 (as shown in FIGURE 10C) may generate a second set of modified regions 502B (as shown in FIGURE 10D), and a third exposure at a different nonnormal angle relative to the surface of substrate 110 (as shown in FIGURE 10D) may generate a third set of modified regions 502C (as shown in FIGURE 10E). Subsequently, microspheres 302 may be removed, and a chemical or plasma etch may be applied to remove modified regions 502A, 502B, and 502C (not explicitly shown), forming nanostructures on the surface of substrate 110. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0065] 11

[0066] Although FIGURES 10A-10E depict multiple exposures at different angles, it is understood that in some embodiments, one or more non-normal angled exposures may be made, resulting in non-normal modified regions, such as non-normal modified regions 502B and 502C, which may be removed to form non-normal angled nanostructures on the surface of substrate 1 10. Exposures at different angles may vary the physical (e.g., optical or mechanical) properties of substrates. Further, the use of multiple exposures and / or non-normal angled exposures may increase density over the single-exposure approach shown in FIGURES 3-7.

[0067] In some embodiments, non-normal angled exposures may be overlapping, (e.g., with overlapping non-normal modified regions 502B and 502C).

[0068] In yet other embodiments, a continuous exposure over varying angles approach may be used, in which substrate 110 may be placed under lens 104, and a single continuous exposure (e.g., starting at an angle similar to that shown in FIGURE 10C and ending at an angle similar to that shown in FIGURE 10D) may generate a series of periodic, annular-shaped modified regions 1102 as shown in FIGURE 11. Subsequently, microspheres 302 may be removed, and a chemical or plasma etch may be applied to remove modified regions 1100 (not explicitly shown), forming annularshaped nanostructures on the surface of substrate 1 10.

[0069] FIGURES 12A-12D illustrate an approach to ultrafast laser exposure involving a dielectric phase mask 1200 placed on or proximimate to the surface of substrate 110, such dielectric phase mask 1200 having microstructures and / or nanostructures 1202 used in lieu of microspheres 302 as in the approaches described above, with such dielectric phase mask 1200 being exposed via an exposure 1204 (as shown in FIGURE 12B) in order to form nanostructures 1206 on the surface of substrate 110, as shown in FIGURE 12D.

[0070] The systems and methods described herein may enable creation of surface structures with finer and denser features, as compared to existing approaches. Further, the systems and methods described herein may enable patterning of features on ultra- hard, single-crystal materials, which is traditionally challenging to do. In addition, the ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0071] 12 systems and methods disclosed herein may enable fabricating nanostructures with concave profiles (e.g., as shown in FIGURE 7), which may give a substrate surface improved mechanical properties such as scratch resistance, hardness, and stiffness, as compared to traditional approaches.

[0072] As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electrical, mechanical, or electromechanical communication, whether connected indirectly or directly, with or without intervening elements.

[0073] This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to. enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

[0074] Although exemplary' embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0075] 13 of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described above.

[0076] Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale.

[0077] All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art. and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.

[0078] Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the foregoing figures and description.

[0079] To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. § 112(f) unless the words “means for’" or “step for” are explicitly used in the particular claim.

[0080] The clauses below set out features of the present disclosure.

[0081] 1. A method comprising: directing an ultrafast laser beam onto a surface of a substrate coated with dielectric microparticles such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0082] 14

[0083] 2. The method of Clause 1, wherein the substrate comprises sapphire.

[0084] 3. The method of Clause 2. wherein the substrate comprises single-crystal sapphire.

[0085] 4. The method of Clause 3, wherein physically modified regions of material comprise amorphous or poly crystalline sapphire.

[0086] 5. The method of Clause 1, wherein the substrate comprises a singlecrystal crystalline material.

[0087] 6. The method of Clause 5, wherein physically modified regions of material comprise amorphous or poly crystalline material.

[0088] 7. The method of Clause 1, wherein the substrate comprises one of aluminium oxynitride (A1ON), magnesium aluminate spinel (MgAhC ), yttrium aluminum garnet (Y AG), or a hard ceramic.

[0089] 8. The method of Clause 1, wherein the ultrafast laser beam has pulses between approximately 35 fs and approximately 120 fs.

[0090] 9. The method of Clause 1, wherein the ultrafast laser beam has a center wavelength of approximately 800nm.

[0091] 10. The method of Clause 1. wherein the dielectric microparticles comprise polystyrene particles. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0092] 15

[0093] 11. The method of Clause 10, wherein the polystyrene particles are approximately 10 pm in diameter.

[0094] 12. The method of Clause 1. wherein the dielectric microparticles comprise silica particles.

[0095] 13. The method of Clause 12, wherein the silica particles are between approximately 200nm and approximately 20pm in diameter.

[0096] 14. The method of Clause 1, wherein the nanostructures have a concave profile.

[0097] 15. The method of Clause 1. wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing multiple exposures of the ultrafast laser beam through each dielectric microparticle.

[0098] 16. The method of Clause 15, wherein at least one of the multiple exposures is at an angle non-normal to the surface.

[0099] 17. The method of Clause 15, wherein at least two of the multiple exposures are overlapping.

[0100] 18. The method of Clause 1 , wherein directing the ultrafast laser beam onto the surface of the substrate comprises directing the ultrafast laser beam onto the surface at an angle non-normal to the surface.

[0101] 19. The method of Clause 1 , wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing a continuous exposure of the ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0102] 16 ultrafast laser beam through each dielectric microparticles at varying angles of exposure.

[0103] 20. The method of Clause 1. wherein the dielectric microparticles comprise dielectric microspheres.

[0104] 21. A system, comprising: a first subsystem configured to coat a surface of a substrate with dielectric microparticles; a second subsystem configured to direct an ultrafast laser beam onto the surface of the substrate such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and a third subsystem configured to etch the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

[0105] 22. The system of Clause 21, wherein the ultrafast laser beam has pulses between approximately 35 fs and approximately 120 fs.

[0106] 23. The system of Clause 21, wherein the ultrafast laser beam has a center wavelength of approximately 800nm.

[0107] 24. The system of Clause 21, wherein the dielectric microparticles comprise polystyrene particles.

[0108] 25. The system of Clause 24, wherein the polystyrene particles are approximately 10 pm in diameter. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0109] 17

[0110] 26. The system of Clause 21, wherein the dielectric microparticles comprise silica particles.

[0111] 27. The system of Clause 26, wherein the silica particles are between approximately 200nm and approximately 20pm in diameter.

[0112] 28. The system of Clause 21, wherein the nanostructures have a concave profile.

[0113] 29. The system of Clause 21, wherein the second subsystem is further configured to direct the ultrafast laser beam onto the surface of the substrate byperforming multiple exposures of the ultrafast laser beam through each dielectric microparticle.

[0114] 30. The system of Clause 29, wherein at least one of the multiple exposures is at an angle non-normal to the surface.

[0115] 31 . The system of Clause 29, wherein at least two of the multiple exposures are overlapping.

[0116] 32. The system of Clause 21, wherein the second subsystem is further configured to direct the ultrafast laser beam onto the surface of the substrate at an angle non-normal to the surface.

[0117] 33. The system of Clause 21, wherein the second subsystem is further configured to direct the ultrafast laser beam onto the surface of the substrate by performing a continuous exposure of the ultrafast laser beam through each dielectric microparticle at varying angles of exposure. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0118] 18

[0119] 34. The system of Clause 21, wherein the dielectric microparticles comprise dielectric microspheres.

[0120] 35. A method for preparing a substrate for creation of nanostructures upon a surface of the substrate, the method comprising: coating the surface of the substrate with dielectric microparticles.

[0121] 36. The method of Clause 35, wherein the substrate comprises sapphire.

[0122] 37. The method of Clause 36, wherein the substrate comprises singlecrystal sapphire.

[0123] 38. The method of Clause 37. wherein physically modified regions of material comprise amorphous or poly crystalline sapphire.

[0124] 39. The method of Clause 35, wherein the substrate comprises a singlecrystal crystalline material.

[0125] 40. The method of Clause 35, wherein the substrate comprises one of aluminium oxynitride (A1ON), magnesium aluminate spinel (MgAhC ), yttrium aluminum garnet (YAG), or a hard ceramic.

[0126] 41. The method of Clause 35, wherein the dielectric microparticles comprise polystyrene particles.

[0127] 42. The method of Clause 41, wherein the polystyrene particles are approximately 10 pm in diameter. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0128] 19

[0129] 43. The method of Clause 35, wherein the dielectric microparticles comprise silica particles.

[0130] 44. The method of Clause 43, wherein the silica particles are between approximately 200nm and approximately 20pm in diameter.

[0131] 45. The method of Clause 35, wherein coating the surface of the substrate with dielectric microparticles comprises using one of drop casting, spin coating, Langmuir-Blodgett assembly, and spraying of the dielectric microparticles.

[0132] 46. The method of Clause 35, wherein the dielectric microparticles comprise dielectric microspheres.

[0133] 47. An apparatus comprising: a substrate; and nanostructures formed on the surface of the substrate by directing an ultrafast laser beam onto the surface of a substrate coated with dielectric microparticles such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate which are removed via etching.

[0134] 48. The apparatus of Clause 47, wherein the substrate comprises sapphire.

[0135] 49. The apparatus of Clause 48, wherein the substrate comprises singlecrystal sapphire.

[0136] 50. The apparatus of Clause 49, wherein physically modified regions of material comprise amorphous or poly crystalline sapphire. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0137] 20

[0138] 51. The apparatus of Clause 47, wherein the substrate comprises a singlecrystal cry stalline material.

[0139] 52. The apparatus of Clause 51, wherein physically modified regions of material comprise amorphous or poly crystalline material.

[0140] 53. The apparatus of Clause 47, wherein the substrate comprises one of aluminium oxynitride (A1ON), magnesium aluminate spinel (MgAhO4), yttrium aluminum garnet (Y AG), or a hard ceramic.

[0141] 54. The apparatus of Clause 47, wherein the ultrafast laser beam has pulses between approximately 35 fs and approximately 120 fs.

[0142] 55. The apparatus of Clause 47, wherein the ultrafast laser beam has a center wavelength of approximately 800nm.

[0143] 56. The apparatus of Clause 47, wherein the dielectric microparticles comprise polystyrene particles.

[0144] 57. The apparatus of Clause 56. wherein the polysty rene particles are approximately 10 pm in diameter.

[0145] 58. The apparatus of Clause 47, wherein the dielectric microparticles comprise silica particles.

[0146] 59. The apparatus of Clause 48, wherein the silica particles are between approximately 200nm and approximately720pm in diameter. ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)

[0147] 21

[0148] 60. The apparatus of Clause 47, wherein the nanostructures have a concave profile.

[0149] 61. The apparatus of Clause 47, wherein the dielectric microparticles comprise dielectric microspheres.

[0150] 62. A method comprising: arranging a dielectric phase mask comprising microstructures and / or nanostructures such that the microstructures and / or nanostructures are proximate to the surface of a substrate; directing an ultrafast laser beam through the dielectric phase mask and to a surface of the substrate such that the microstructures and / or nanostructures serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

Claims

ATTORNEY’ S DOCKET PCT PATENT APPLICATION215595.00259 (8391 CHA PCT)22WHAT IS CLAIMED IS:

1. A method comprising: directing an ultrafast laser beam onto a surface of a substrate coated with dielectric microparticles such that the dielectric microparticles sen e as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

2. The method of Claim 1, wherein the substrate comprises one of sapphire, aluminium oxynitride (A1ON), magnesium aluminate spinel (MgALCh), yttrium aluminum garnet (YAG). or a hard ceramic.

3. The method of Claim 1, wherein the substrate comprises a singlecrystal crystalline material.

4. The method of Claim 1, wherein the dielectric microparticles comprise one of polystyrene particles and silica particles,5. The method of Claim 1, wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing multiple exposures of the ultrafast laser beam through each dielectric microparticle.

6. The method of Claim 5, wherein at least one of the multiple exposures is at an angle non-normal to the surface.

7. The method of Claim 6, wherein at least two of the multiple exposures are overlapping.ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)238. The method of Claim 1, wherein directing the ultrafast laser beam onto the surface of the substrate comprises directing the ultrafast laser beam onto the surface at an angle non-normal to the surface.

9. The method of Claim 1, wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing a continuous exposure of the ultrafast laser beam through each dielectric microparticles at varying angles of exposure.

10. The method of Claim 1, wherein the dielectric microparticles comprise dielectric microspheres.ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)2411. A system, comprising: a first subsystem configured to coat a surface of a substrate with dielectric microparticles; a second subsystem configured to direct an ultrafast laser beam onto the surface of the substrate such that the dielectric microparticles serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and a third subsystem configured to etch the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

12. The system of Claim 11, wherein the substrate comprises one of sapphire, aluminium oxynitride (A1ON), magnesium aluminate spinel (MgAbC ), yttrium aluminum garnet (YAG), or a hard ceramic.

13. The system of Claim 11, wherein the substrate comprises a singlecrystal crystalline material.

14. The system of Claim 11, wherein the dielectric microparticles comprise one of polystyrene particles and silica particles,15. The system of Claim 1 1, wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing multiple exposures of the ultrafast laser beam through each dielectric microparticle.

16. The system of Claim 15. wherein at least one of the multiple exposures is at an angle non-normal to the surface.ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)2517. The system of Claim 16, wherein at least two of the multiple exposures are overlapping.

18. The system of Claim 11. wherein directing the ultrafast laser beam onto the surface of the substrate comprises directing the ultrafast laser beam onto the surface at an angle non-normal to the surface.

19. The system of Claim 11. wherein directing the ultrafast laser beam onto the surface of the substrate comprises performing a continuous exposure of the ultrafast laser beam through each dielectric microparticles at varying angles of exposure.ATTORNEY’S DOCKET PCT PATENT APPLICATION 215595.00259 (8391 CHA PCT)2620. A method comprising: arranging a dielectric phase mask comprising microstructures and / or nanostructures such that the microstructures and / or nanostructures are proximate to the surface of a substrate; directing an ultrafast laser beam through the dielectric phase mask and to a surface of the substrate such that the microstructures and / or nanostructures serve as lenses to focus photonic nanojets of the ultrafast laser beam onto selected portions of the surface to generate physically modified regions of material within the substrate; and etching the substrate to remove the physically modified regions of material within the substrate to form nanostructures on the surface of the substrate.

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