Laser light hair cutting device

Abstract

Described herein includes a hair cutting device configured for safe, efficient optical hair cutting through external waveguide light guiding and temporary tissue integration. The device comprises an optical waveguide configured to guide laser light outside the waveguide material along a cutting surface of a cutting region of the waveguide and / or accept organic tissue (hair) as a temporary integral component of the waveguide system. Applications include personal grooming devices, professional hair cutting implements, and medical cutting instruments with inherent safety and efficiency advantages over mechanical and prior art optical approaches.

Description

SHAVE THE WORLDCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 687,181 , filed August 26, 2024, entitled "Photonic Razor," the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates generally to optical devices and methods for cutting organic tissue, particularly hair cutting devices that utilize laser light for safe and efficient hair removal.

[0003] More specifically, the disclosure relates to optical waveguide systems configured to guide electromagnetic modes outside the waveguide material and to accept organic tissue as temporary integral components of the waveguide system during cutting operations.BACKGROUND

[0004] Shaving with mechanical blades is an ancient practice that continues to be afflicted with skin irritation and tissue damage. For the past 20 years, the shaving industry has attempted unsuccessfully to bring to market and reduce to practice the art of non-irritating or less skinafflicting shaving using light or laser light instead of mechanical blades.

[0005] Despite significant investment and research efforts, there remains an unmet need and public demand for an eye-safe and skin-safe laser shaver that does not cause irritation.SUMMARY

[0006] Generally, a device according to the present disclosure can be configured to cut hair using laser light includes a handle portion and a shaving portion. The handle portion includes a battery and a laser light source. The laser light source is coupled to and configured to receive power from the battery. The laser light source is also configured to generate laser light having a wavelength selected to target a predetermined chromophore to effectively cut a hair shaft. The shaving portion includes a support and an optical waveguide supported by the support. The optical waveguide has a proximal end, a distal end, an outer sidewall wall with a cutting region along the waveguide and a cutting face along the cutting region. The optical waveguide is positioned to receive the laser light from the laser light source at the proximal end, conduct the laser light from the proximalend toward the distal end, and guide the laser light outside and along the cutting face and in hair when the cutting face is brought in optical contact with the hair

[0007] In some embodiments, the hair cutting device can comprise a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting hair, and wherein the optical waveguide configured such that electromagnetic modes of the light propagate guided by the waveguide outside the cutting face.

[0008] In some embodiments, the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided outside the cutting face.

[0009] In some embodiments, the hair cutting device can comprise a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting hair, and wherein the optical waveguide is configured to accept hair as an integral component of the waveguide.

[0010] In some embodiments, the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided in the hair when hair is accepted as an integral component of the waveguide.

[0011] In some embodiments, the hair cutting device can comprise a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting hair, and wherein the optical waveguide is configured such that electromagnetic modes of the light propagate guided by the waveguide outside the cutting face, and wherein the optical waveguide is configured such that electromagnetic modes of the light propagate guided by the waveguide in hair when hair is in contact with the cutting face, and wherein the hair is an integral part of the waveguide.

[0012] In some embodiments, the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided outsidethe waveguide material, and configured to control the percentage of laser light guided in the hair when hair is accepted as an integral component of the waveguide.

[0013] In other embodiments, the waveguide is configured to establish optical contact with hair through at least one of: secondary cladding integration, effective core formation, and modeguiding integration.

[0014] In some embodiments, at least 10% of the laser light is guided outside the cutting face.

[0015] In some embodiments, at least 50% of the laser light is guided outside the cutting face.

[0016] In some embodiments, at least 90% of the laser light is guided outside the cutting face.

[0017] In other embodiments, the optical waveguide comprises a core having a refractive index higher than the refractive index of hair.

[0018] In some embodiments, the optical waveguide comprises a top cladding that comprises a thickness configured to control the percentage of laser light guided outside the cutting face.

[0019] In other embodiments, the waveguide is configured to not emit radiant modes from the cutting face.

[0020] In some embodiments, the optical waveguide is configured to prevent the laser light from guiding or coupling in materials having a refractive index of or below 1.52 outside the cutting surface.

[0021] In other embodiments, the optical waveguide comprises a bottom cladding, or a core, or a top cladding, comprising a dimension selected from the group of a thickness, a width, a cross- sectional diagonal, and a diameter, that is chosen from the group of: less than 4 pm, 5 nm to 900 nm, or 1 m to 10um.

[0022] In some embodiments, the hair cutting device further comprises at least one sensor configured to monitor optical feedback from hair.

[0023] In some embodiments, the hair cutting device further comprises comprising a power and control system configured to deliver laser light in pulses.

[0024] In some embodiments, the optical waveguide is configured to operate without emission from the cutting face.

[0025] In some embodiments, the method of cutting hair on a body of a subject can comprise guiding a light source for generating laser light at hair, wherein the wavelengths are corresponding to wavelengths absorbed by one or more chromophores in hair.

[0026] In some embodiments, the method of cutting hair on a body of a subject can comprise guiding a light source for generating laser light in hair, wherein the wavelengths are corresponding to wavelengths absorbed by one or more chromophores in hair.DETAILED DESCRIPTION OF DRAWINGS

[0027] FIG. 1A shows one embodiment 100a of the disclosure in the form of a laser razor comprising a handle portion 101 and a cutting portion 102 connected to the handle portion. The handle portion comprises a power source 103 in the form of a battery or of a power line intake, and electrical circuitry 104 for operating a laser driver 105. The power source 103 is electrically connected to the electrical circuitry 104. The electrical circuitry 104 is electrically connected to the laser driver 105. The cutting portion comprises support 106, a laser diode 107, a straight optical waveguide 108a with a sidewall cutting surface 110a, and a light quenching mechanism 109. The laser driver 105 is electrically connected to the laser diode 107. The laser diode 107 is optically coupled to the straight waveguide 108a. The straight waveguide 108a is optically coupled to the light quenching mechanism 109.

[0028] FIG. 1 B shows another embodiment 100b of the disclosure in the form of a laser razor comprising a handle portion 101 and a cutting portion 102 connected to the handle portion. The handle portion comprises a power source 103 in the form of a battery or of a power line intake, and electrical circuitry 104 for operating a laser driver 105. The power source 103 is electrically connected to the electrical circuitry 104. The electrical circuitry 104 is electrically connected to the laser driver 105. The cutting portion comprises a support 106, a laser diode 107, an optical waveguide 108b comprising a waveguide bend 108c and a sidewall cutting surface 110b, and a light quenching mechanism 109. The laser driver 105 is electrically connected to the laser diode 107. The laser diode 107 is optically coupled to the waveguide 108b. The waveguide 108b is optically coupled to the light quenching mechanism 109.

[0029] FIG. 2A shows one embodiment 108c of the side view 110c of the waveguide 108a in FIG. 1 A. The components of FIG. 2A is not to scale but shall be viewed as an illustration of the principle construction of one embodiment of the waveguide 108a in FIG 1A. The waveguide in FIG. 2A rests on a substrate 111 and comprises a bottom cladding 112, a core 113, and a top cladding 114a and 114b. The laser diode 107 of FIG. 2A is coupled to a first end 116a of the core 113. The core has a second end 116b that is coupled to the light quenching mechanism 109 if FIG. 1A. The waveguide embodiment of FIG. 2A has top view surface surfaces 115a, 115b and 115c, incongregate depicted as surface 110a in FIG. 1A. The side view 110c of an embodiment of the waveguide 108b in FIG.1 B is the same one as the one of the waveguide 108a in FIG. 1A, but with the addition of the bend 108c in FIG. 2B

[0030] FIG. 2B shows another embodiment 108d of the side view 110c of the waveguide 108a in FIG. 1A. The components of FIG. 2A is not to scale but shall be viewed as an illustration of the principle construction of one embodiment of the waveguide 108a in FIG. 1A. The waveguide in FIG. 2A rests on a substrate 111 and comprises a bottom cladding 112, a core 113, and a top cladding comprising in congregate 114a, 114b, and 114c. The laser diode 107 of FIG. 2A is coupled to a first end 116a of the core 113. The core has a second end 116b that is coupled to the light quenching mechanism 109 if FIG. 1A. The waveguide embodiment of FIG. 2A has top view surface surfaces 115a, 115b and 115c, in congregate depicted as surface 110a in FIG. 1A. The side view 110c of an embodiment of the waveguide 108b in FIG. 1 B is the same one as the one of the waveguide 108a in FIG. 1A, but with the addition of the bend 108c in FIG. 2B.

[0031] FIG. 3A shows in more detail one embodiment 120a of the waveguide from the top view 110a in FIG. 1A, and added the same top view of the quenching mechanism (109 in FIG. 1A) 127. This embodiment comprises a top cladded waveguide section 121 with a top vies surface 121a, a gradually narrowing width transition section 122 of the waveguide comprising a gradually thinning (not shown in this view) top cladding with top view surface 122a towards a narrowed and uncladded section of the waveguide 123 having a top view surface123a, a gradually widening width transition section 124 of the waveguide comprising a gradually thickening (not shown in this view) top cladding having a top view surface 124a towards a top cladded wider waveguide section 125. In some embodiments the waveguide is connected or continued by a light quenching mechanism 127. In some embodiments the waveguide comprises a top mounted photosensor 126 for detecting light guided by the waveguide. Waveguide sections 12, 122, 123, 124, 125, and any light quenching mechanism 127 are connected in sequence. A photo sensor 126 may be mounted or connected at various locations along the length of the waveguide, including along waveguide section 125.

[0032] FIG. 3B shows in more detail one embodiment 120b of the waveguide from the top view 110a in FIG. 1A, and added the same top view of the quenching mechanism (109 in FIG. 1A) 127. This embodiment comprises a top cladded waveguide section 121 with a top vies surface 121a, a gradually narrowing width transition section 122 of the waveguide comprising a gradually thinning (not shown in this view) top cladding with top view surface 122a towards a narrowed and thinner cladded section of the waveguide 128 having a top view surface128a, a graduallywidening width transition section 124 of the waveguide comprising a gradually thickening (not shown in this view) top cladding having a top view surface 124a towards a top cladded wider waveguide section 125. In some embodiments the waveguide is connected or continued by a light quenching mechanism 127. In some embodiments the waveguide comprises a top mounted photosensor 126 for detecting light guided by the waveguide. Waveguide sections 12, 122, 123, 124, 125, and any light quenching mechanism 127 are connected in sequence. A photo sensor 126 may be mounted or connected at various locations along the length of the waveguide, including along waveguide section 125.

[0033] FIG. 4 shows an embodiment 130 of the waveguide 108a respective 108b of FIGs 1A and 1 B, from the side view 116a of FIGs 2A and 2B, and wherefrom the laser diode 107 in FIGs 1A and 1 B connect to the waveguide. The waveguide 130 comprises substrate 131 , a bottom cladding 132, a core 133, and a top cladding 134. The laser diode 107 of FIGs 1A and 1 B couples into surface 133b.

[0034] FIG 5 shows a face from the side with one embodiment according to the disclosure doing a shaving stroke in the direction of the arrow 143. The skin of the face has an area 142 with beard and hair straws, and another area 144 shaven clean by a device comprising the handle portion of FIG. 1A 101 141 and the cutting portion of FIG. 1A 102, 142. FIG. 5 intends to depict the cutting surface of the sidewall of a waveguide of FIG. 1 A 110a adjacent to or in closeness to with skin, moving parallel to and along the skin's surface and perpendicular against the hair, or moving perpendicular to and along the skin's surface, or both.

[0035] FIG. 6 shows a graphical distribution of data from Finite Element Analysis (FEA) of the propagation losses for five exemplary waveguides of different thickness, and increasing widths from left to right.

[0036] FIG. 7 shows percentage of confinement in the analyte (the space outside and on top of a sidewall face of a waveguide) for five exemplary refractive indices (n) of the organic material in the analyte, and at increasing widths from left to right.

[0037] FIG. 8 shows the transmission percentages of light through six different hair colors over incident light of 400nm to 1100nm.

[0038] FIG. 9 shows a cross-sectional view of a waveguide structure showing substrate (C), bottom cladding / insulator (B), waveguide core (A), and optional top cladding (D), with cutting surface (1) and light coupling regions (2,3,4).

[0039] FIG. 10 shows a cross-sectional view similar to FIG. 3, showing an alternative embodiment with different cladding configuration and light guiding surface (1) with coupling region (3).

[0040] FIG. 11 shows a top view of a waveguide showing wide section (A), tapered transition section (B), narrow cutting section (C), sensor / termination area (1), and light input coupling area (5).

[0041] FIG. 12 shows cross-sectional views (A,B,C,D) showing various aspect ratios and dimensional configurations (1,2, 3, 4) applicable to different waveguide sections.

[0042] FIG. 13 shows side view showing waveguide sections: light input section (A), tapered transition section (B), and cutting section (C) corresponding to FIG. 9 and 10.

[0043] FIG. 14A shows a top view of complete waveguide system showing proximal wide section (A), first tapered section (B), narrow cutting section (C), second tapered section (D), distal wide section (E), input end (5), and output end (6).

[0044] FIG. 14B shows an end view of cross-sectional area (6) showing top cladding (F), waveguide core (G), substrate (H), and bottom cladding (I).

[0045] FIG. 14C shows a cross-sectional view of cutting region (C) without top cladding, showing waveguide core (J), substrate (K), and bottom cladding (L).

[0046] FIG. 14D shows cross-sectional view of cutting region with top cladding, showing waveguide core (M), substrate (N), and top cladding (O).

[0047] FIG. 15 shows a top view showing tapered input coupling configuration with surfaces (5a, 5b, 5c) for enhanced laser diode mode coupling.

[0048] FIG. 16 shows a schematic diagram of a hair cutting device according to the present disclosure, showing the waveguide positioned relative to skin and hair during operation, and descriptions.DETAILED DESCRIPTION

[0049] The present disclosure represents a fundamental breakthrough in optical organic tissue (hair) cutting technology through the recognition that optical waveguides can be configured to guide electromagnetic modes outside the waveguide material and to accept organic tissue as optionally temporary integral components of the waveguide system.

[0050] This eliminates the safety hazards and efficiency limitations that have prevented practical implementation of prior art laser-based hair cutting devices.

[0051] Existing approaches to laser-based hair cutting have been taught by Gustavsson et al. in U.S. Patent No. 10,959,777 and by Bourquin et al. in U.S. Patent Application Publication No. US2018034404 A1. These prior art devices utilize laser light from a side-emitting waveguide positioned to emit light from an outer sidewall of the waveguide to hair.

[0052] Such prior art devices suffer from several critical limitations that have prevented practical implementation:

[0053] Safety Hazards: Prior art devices inherently comprise optical hazards to eyes and skin, as well as thermal hazards to users. As shown by van Kampen et al. (1997), blonde organic tissue (hair) transmits 50-80% of light between 450 nm and 900 nm, and brown organic tissue (hair) transmits 30-50% of light in this range (see FIG. 1). At least 50% to 80% of light emitted to organic tissue (hair) passes through the organic tissue (hair) and can continue toward eyes or skin, creating significant safety risks.

[0054] Extremely Low Efficiency: Side-emitting systems are highly inefficient in light coupling to organic tissue (hair), with theoretical maximum coupling efficiency of only about 0.01% of guided light for an optical fiber and less than about 1% for a planar or channel waveguide, or other waveguides. This requires impractically high power levels for effective operation.

[0055] Manufacturing Impossibility: An eccentric core optical fiber required for side emission cannot be manufactured with necessary core size and durability. The smallest usable eccentric core diameter known to be manufactured is 10 pm, which still provides inadequate coupling efficiency. Other waveguides for side emission cannot be manufactured to practically usable levels of either coupling efficiency, or propagation losses, or both.

[0056] Thermal Management Challenges: The 99% - 99.99% of unutilized light creates severe thermal management problems requiring unrealistic cooling systems for portable devices. Cooling the laser light source (laser diode) creates an even bigger challenge. Together unsurmountable.

[0057] Power Source Limitations: Low efficiency necessitates large battery systems incompatible with practical handheld devices.

[0058] The prior art teaches waveguides with refractive indices lower than organic tissue (hair) (-1.54) to enable side-emission. However, this approach suffers from fundamental physical limitations. Light transmission through organic tissue (hair) varies from 20-40% for violet / bluewavelengths to 40-80% at 1100 nm wavelengths. Light emitted toward organic tissue (hair) and transmitted through organic tissue (hair) creates eye and skin hazards. Mode coupling efficiency remains below 1 % for some systems and 0.01 % for others even with theoretical optimizations.

[0059] In the prior art of the eccentric fiber core, attempts are made to improve efficiency through thin film coatings with higher refractive indices, but such coatings cannot survive the mode disruption caused by mode-step transitions along the waveguide length. Even if such coatings could survive, the resulting coupling efficiency would remain inadequate for practical organic tissue (hair) cutting applications.

[0060] Despite extensive research and development efforts, no practical laser-based organic tissue (hair) cutting device has been successfully commercialized due to the fundamental limitations of side-emitting approaches. There remains a critical need for a laser organic tissue (hair) cutting system that provides eye and skin safety through elimination of emission-based light delivery, high efficiency light coupling to organic tissue (hair) for practical power requirements, manufacturable waveguide structures using established fabrication processes, manageable thermal characteristics compatible with portable devices, and reliable operation without emission- related safety hazards.

[0061] The present disclosure can address these longstanding problems through a fundamentally different approach that eliminates the limitations of prior art side-emitting systems.

[0062] The present disclosure provides a revolutionary hair cutting device with a cutting element that overcomes the fundamental limitations of prior art through three complementary technical solutions: (1) external light guiding along waveguide surfaces, (2) temporary integration of organic tissue (hair) as a waveguide component, and (3) hybrid operational modes. All approaches maintain waveguide integrity while providing safe, efficient light delivery to hair.

[0063] By moving an optical waveguide providing light from a laser guided outside one sidewall surface, and moving that sidewall surface perpendicular or at a somewhat steep angle to organic material (hair), and optionally parallel to a surface such as skin, the light guided outside the surface of that sidewall of the waveguide can couple from the waveguide into organic tissue (hair having a refractive index n=1.54) - see FIG. 7. The light guided in the hair can convert in part to heat by absorption of light in the hair - see FIG. 8. That heat can sever the hair. Light not absorbed by the organic material (hair) continues guided in the waveguide by controlling waveguide dimensions and cross-sectional aspect ratios and refractive index relationships - see FIG. 7. For example, electromagnetic modes can be "squeezed" outside the waveguide surface thewaveguide and in hair, and back into the waveguide after passing through the hair. The waveguide can be attached to a mechanical support and handle structures similar in ergonomic shave to any shape of a conventional razors and shavers and groomers, shown by example of in FIG. 1A and FIG. 1 B, and with the in this manner positioned hair cutting waveguide positioned substantially at the same location as in conventional devices. The device can have other shapes. The shaving motion over skin can be similar to with conventional shaving devices. Shaving with laser light can have many and significant advantages over shaving with sharp mechanical blades, as will be described later in the following.

[0064] Unlike prior art devices that emit light with associated safety hazards and low efficiency, the present disclosure guides electromagnetic modes outside the waveguide material while maintaining waveguide integrity. This eliminates emission-based safety risks while achieving electric mode guiding efficiencies up to 99.99% in the analyte, see FIG. 7. The analyte is the space outside the surface of the waveguide material wherein guided squeezed out modes can roam.

[0065] First Solution - External Light Guiding: A cutting element comprising an optical waveguide configured to guide laser light outside the waveguide material along a cutting face comprising the waveguide surface of a cutting region of the waveguide. By controlling waveguide dimensions and cross-sectional aspect ratios including for low propagation losses - see FIG. 6, and refractive index relationships - see FIG. 7, electromagnetic modes can be "squeezed" outside the waveguide surface and into the analyte where they can interact with organic tissue (hair) while remaining guided, hence confined by the waveguide, rather than emitted.

[0066] Second Solution - Temporary Tissue Integration: A cutting face of a sidewall of a cutting region of an optical waveguide is configured to accept predetermined organic tissue (hair) as a temporary integral component of the waveguide system. By controlling waveguide dimensions and cross-sectional aspect ratios including for low propagations - see FIG. 6, and refractive index relationships - see FIG. 7, guided electromagnetic modes can be "squeezed" outside the waveguide material in the analyte by means of natural mode evolution that occurs from the original waveguide and only to predetermined organic tissue (hair with refractive index n=1 ,54) - see FIG. 7, and only when organic tissue (hair) optically contacts the cutting face. This creates a composite waveguide system with up to 99.99% coupling efficiency into the organic tissue (hair) - see FIG. 7.

[0067] Third Solution - Hybrid Operation: The device combines external guiding and temporary integration solutions, providing operational flexibility and optimization for different organic material (hair) characteristics and cutting conditions.

[0068] The disclosure provides superior safety by eliminating emission-based light delivery to organic tissue (hair), preventing eye and skin exposure to light transmitted through the hair, and optionally also creating bulbous hair terminations that cannot penetrate skin. Ultra-high efficiency can be achieved with up to 99.99% mode confinement in organic tissue (hair) - see FIG. 6, versus up to about 1 % for some systems and 0.01% for others in the prior art. Ultra-low waveguide propagation losses along the cutting region demonstrate propagation losses of about 0.2 dB / cm to about 1.0 dB / cm - see FIG. 6, enabling practical device implementation. Manufacturability is ensured through compatibility with standard CMOS and photonic integrated circuit (PIC) fabrication processes with nanometric precision. Practical implementation features manageable power requirements and thermal characteristics for hand confined portable devices as well as intelligent optical feedback control systems. Self-regulating operation provides automatic cutting termination upon (organic tissue) hair severance with real-time detection and power control via photosensors - see FIG.3A 126, and FIG.3B 126. Index selectivity enables selective operation only with materials having refractive indices higher or equal to a threshold, for example the refractive index of organic tissue (hair), eliminating light guiding and interaction with ambient materials such as water, skin, and debris - see FIG. 7.

[0069] The disclosure can be manufactured using, but not limited to, established semiconductor foundry infrastructure including CMOS fabrication processes. This enables high-volume, low-cost production with proven quality control and reliability, addressing the manufacturability challenges that have prevented commercialization of prior art approaches.

[0070] The disclosure encompasses various embodiments including but not limited to planar waveguides, multi-waveguide systems, and devices configured for different organic tissue cutting applications beyond hair removal. The device may function as razors, shavers, groomers, scalpels, scissors, or other cutting implements with inherent selectivity, safety and efficiency advantages over both mechanical and prior art optical approaches.

[0071] The core principle of external light guiding involves controlling waveguide geometry and refractive index relationships to "squeezed" guided electromagnetic modes outside the physical boundaries of the waveguide material, into the analyte. - see FIG. 6 and FIG. 7. The analyte is the space outside the surface of the waveguide material wherein guided squeezed out modescan roam. This creates "squeezed-out electromagnetic modes" that can achieve app to 99.99% mode confinement in the analyte, including in organic tissue (hair) - see FIG. 7.

[0072] Unlike coupling light to organic tissue (hair) by means of permeation, diffraction, refraction, evanescent field coupling or frustrated total internal reflection (FTIR), this approach maintains true guided propagation outside the waveguide while preserving waveguide integrity. This is true also under conditions of non-matching propagation constants between the waveguide and the analyte, for example between the waveguide material and organic tissue (hair), versus the opposite being the case for FTIR.

[0073] Key parameters controlling external light guiding include waveguide thickness, cross- sectional aspect ratio (width / height) -see FIG.6, refractive index of waveguide core relative to surrounding materials, wavelength of guided light - see FIG.7, and presence and thickness or not of cladding layers along the cutting face - see FIG.2A 115a, 2B 114c, 3A 128a, 3B 123b, 9, 10, and 14, in congregate creating squeezed-out mode distribution.

[0074] Organic tissue (hair) absorbs 50-80% of the guided light - see FIG.8; causing thermal severing at temperatures of 64°C or higher in the hair due to melting of the Integral Lipid Layer (ILL), and; optionally creating bulbous organic tissue (hair) terminations by denaturing collagen. Bulbous hair terminations cannot penetrate skin and can hence prevent a medical condition known as pseudofolliculitis barbae (PFB). Per scholarly literature, the lipids of the ILL melts at about 64 degrees C; they are the only continuous structure of the skin, they are what is connecting the collagen particles of the hair with each other and does so by disulfide bridges between the lipids and collagen particles; they also cover the surface of the hair. By melting the lipids in the ILL the hair falls apart as demonstrated by laboratory experiments. The ILL is equally present in all hair colors. By targeting the ILL as a chromophore, all hair colors can be severed including white and grey hair using light wavelengths of the guided electromagnetic modes that are not absorbed by collagen. Per scholarly literature the collagen denatures at about 150 degrees C, causing plastic deformation of the hair termination, whereas carbonization and associated fume creation occurs at approximately 300 degrees C. This enables bulbous terminations of the hair without the inconvenience and nuisance of smoke and the smell of burnt hair.

[0075] When a material with a predetermined refractive index, for example hair with a refractive index n=1 .54 - see FIG.7, contacts the cutting face of the waveguide - see FIG.2A 114c, and 2B 115a, and FIG.3A 128a, and 3B 123b, the waveguide system undergoes natural mode evolution by means of "squeezed out" modes. Electromagnetic modes transition from confinement in theoriginal waveguide to confinement within the material with a predetermined refractive index, for example organic tissue (hair).

[0076] This creates a temporary composite waveguide system with the organic tissue (hair) functioning as either a secondary cladding or effective core component. When organic tissue (hair) contacts the waveguide, the waveguide-confined mode evolves to guide up to 99.99% of the light in the organic tissue (hair) - see FIG.7, which becomes a momentaneous integral part of the waveguide system as it becomes severed.

[0077] Key parameters controlling mode guiding to include the organic material (hair) include waveguide core thickness - see FIG.7, top cladding thicknesses, and cross-sectional aspect ratio (width / height) including for controlling propagation losses - see FIG.6, refractive index of waveguide core relative to surrounding materials - see . FIG.7, wavelength of guided light, and presence and thickness of cladding layers, see FIG.2A 113 and FIG.2B 114c, in congregate creating squeezed-out mode distribution into the organic material (hair).

[0078] Organic tissue (hair) absorbs 50-80% of the guided light - see FIG.8, causing thermal severing at temperatures of 64°C or higher, optionally creating bulbous organic tissue (hair) terminations that cannot penetrate skin.

[0079] The temporary integration is characterized by natural fundamental mode solutions with optimized coupling efficiency, eigenmode distribution evolution from waveguide to organic tissue, automatic restoration upon tissue severance, enhanced coupling efficiency through direct waveguide integration, and intelligent feedback control through detection of remaining light that evolves back into the waveguide of the photonic integrated circuit as a detection signal.

[0080] Unlike coupling light to organic tissue (hair) by means of permeation, diffraction, refraction, evanescent field coupling or frustrated total internal reflection (FTIR), this approach maintains true guided propagation outside the waveguide while preserving waveguide integrity and achieving zero coupling below a predetermined refractive index threshold, such as including but not limited to a refractive index ranging from of 1.52 to 1.55 - see FIG.7.

[0081] The hair cutting device comprises a supporting body, an electrical power source (such as a battery or line voltage) connected to electronic circuitry including a microcontroller unit (MCU) and a laser driver for operating a laser light source (such as a laser diode), and an optical waveguide positioned to receive light from the laser source and guide it from a first end toward a second end - see FIG.1A, FIG.1 B, FIG.5, and FIG.15.

[0082] The optical waveguide includes a cutting region along a portion of its sidewall where hair contact occurs. The cutting region is specifically configured for external light guiding and / or temporary tissue integration depending on the operational mode selected.

[0083] A device according to the present disclosure may include surface-mounted photosensors on the PIC for real-time hair analysis and intelligent power control through detection of optical feedback signals transmitted as optical or electrical signals from the photosensor to the MCU, and a light quenching mechanism as or at the second end of the waveguide.

[0084] The waveguide or waveguide core may comprise various dimensional configurations optimized for external light guiding. Dimensional ranges for width, height, thickness, cross- sectional diagonal, or diameter may be chosen from ranges including 0.1 pm to 12 pm, 2 pm to 5.5 pm, 1 pm to 2 pm, 750 nm to 1000 nm, 500 nm to 750 nm, 250 nm to 500 nm, 150 nm to 250 nm, 100 nm to 150 nm, 60 nm to 100 nm, 40 nm to 60 nm, 20 nm to 40 nm, 10 nm to 20 nm, 5 nm to 10 nm, 1 nm to 5 nm, 1 nm to 100 pm, 1 nm to 500 nm, 1 nm to 300 nm, 1 nm to 200 nm, 1 nm to 100 nm, 100 nm to 200 nm, 200 nm to 400 nm, 400 nm to 1 pm, 1 pm to 2 pm, 2 pm to 10 pm, 10 pm to 40 pm, 40 pm to 100 pm, 100 pm to 500 pm, 5 nm to 50 nm, 8 nm to 40 nm, and 20 nm to 35 nm. The cutting region may be between 1 mm and 200 mm long, or a length between 5 mm and 50 mm.

[0085] Cross-sectional aspect ratios (width / height) control mode distribution between waveguide interior and exterior regions. The waveguide may comprise one or more aspect ratios chosen from within ranges including 0.5 to 2, 1 to 4, 3 to 5, 3 to 6, 5 to 8, 6 to 7, 8 to 15, 9 to 12, 10 to 30, 15 to 25, 20 to 40, 30 to 70, 35 to 55, 60 to 100, 70 to 400, and 80 to 1000. The device may comprise two or more aspect ratios or one or more gradually changing aspect ratios along the waveguide length.

[0086] The waveguide may comprise straight, curved, flared, or tapered areas along at least one of its dimensions chosen from: cross-sectional diagonal, length, width, height, diameter. The waveguide along the organic tissue affecting or interacting region may comprise straight, curved, flared, or tapered areas along at least part of one of its dimensions.

[0087] For a given core thickness, a wider waveguide section generally minimizes propagation losses for mode transportation, with the exception depicted by the thinnest waveguide "Thickness 1" in FIG. 7, whereas a narrower waveguide section increases the propagation losses as the width comes to enable external light guiding required in cutting regions, with the exception depicted by the thinnest waveguide "Thickness 1" in FIG. 7.

[0088] The waveguide core comprises a refractive index higher than the refractive index of organic tissue (hair) (typically ~1.54 to 1.55) - see FIG. 7, to enable external mode guiding. This fundamental relationship distinguishes the disclosure from prior art systems requiring lower refractive indices of the core. The waveguide may comprise a core comprising a refractive index chosen from ranges including greater than 1.54, between 1.54 and 4.4, between 1 ,54 and 2.4, between 4.2 and 8.0, and between 2.1 and 4.5. In some embodiments, the refractive index of the waveguide or the cutting region of the waveguide comprise a refractive index equal to or lower than the organic tissue.

[0089] The waveguide may be configured to prevent laser light from being guided outside or on top of the surface of the cutting region of the waveguide when the region is not adjacent to, in contact with, or in optical contact with the organic tissue. The waveguide may be configured to prevent radiant modes from being emitted from the surface of the cutting region of the waveguide, including when it is adjacent to, in contact with, or in optical contact with materials having various refractive index relationships to hair and skin.

[0090] A device according to the present disclosure may comprise a bottom cladding of at least part of the waveguide or waveguide core, and / or the organic tissue affecting or interacting region. The bottom cladding may optionally function as an optical insulator and may comprise low-index materials such as SiC>2, doped SiC>2, and fluorinated doped SiC>2 (SiC>2:FI) , or Germanium doped SiO2 (SiC>2:Ge). The bottom cladding prevents mode leakage and maintains waveguide performance. The bottom cladding may comprise other materials.

[0091] The bottom cladding may comprise a thickness group of ranges of 100 nm to 10 pm, 1 pm to 10 pm, 1 pm to 7 pm, 2 pm to 6 pm, and 2 urn to 4 pm. The top cladding may comprise a thickness that is substantially equal or similar to the top cladding.

[0092] A device according to the present disclosure may comprise top cladding on top of at least part of the waveguide or waveguide core. Top cladding configurations can include variable thickness along waveguide length. The top cladding can comprise at least two different thicknesses, one thickness after another along the waveguide length - see FIG. 2B. The top cladding may comprise a thickness equivalent or similar to the thickness of the bottom cladding - see FIG. 4 112 and 114a, including for enhanced facet coupling of the light source. The waveguide may comprise a section with no or thinner top cladding (for example in the cutting region) - seeFIG. 2A and 2B. The top cladding may be configured as mechanically protective layers, or chemically protective layers, or thinner protective layers in cutting regions compared to other waveguide sections - see FIG. 2B and FIG. 3B.

[0093] Preferred top cladding thicknesses include ranges of 5-5,000 nm, 5-500 nm, 1-20 nm, 20- 100 nm, 100-250 nm, 150-250 nm, 200-500 nm, 400-800 nm, 700-1 ,200 nm, 1 nm to 500 nm, 2 nm and 400 nm, 1 nm and 300 nm, 4 nm and 200 nm, 50 nm and 150 nm, 5 nm and 100 nm, 8 nm-40 nm, 15 nm-35 nm, 10 nm-25 nm, and 500 nm to 7 pm.

[0094] The waveguide or cladding may comprise materials chosen from groups including films or thin films, SiC>2, silicon nitride (Si3N4or "SiN"), aluminum nitride (AIN), boron nitride (BN), germanium, titanium dioxide (TiCh), zinc oxide (ZnO), aluminum oxide (AI2O3), depositions via PECVD (plasma enhanced chemical vapor deposition), depositions via LPCVD (low pressure chemical vapor deposition), glass materials, dielectric materials, oxide materials, metal materials, metal oxide materials, nitride materials, silicon, crystal materials, semiconductor materials, fluorine (Fl), materials compatible with CMOS fabrication processes, and materials compatible with BiCMOS fabrication processes.

[0095] Additional materials that may be comprised in the core and / or the cladding include SrTiOs, LaAIOs, MgO, GGG (Gadolinium Gallium Garnet), MgAhO4, MgF2, NaCI, LSAT, NdGaOs, YSZ (Yttria-Stabilized Zirconia), polymers, PMMA (Polymethyl methacrylate), printed polymers, 3D printed polymers, ion infusion materials, ion in glass infusion materials, laser-printed or laser- altered materials, laser or multiphoton laser printed materials in polymer matrix, and laser two- photon or multiphoton laser 3D printed materials in polymer matrix.

[0096] A device according to the present disclosure may comprise substrates including silicon or other substrate materials compatible with semiconductor processing infrastructure, for example Sapphire or Silicon-carbide.

[0097] The waveguide may be chosen from structural configurations including planar waveguides, slab waveguides, surface waveguides, ridge waveguides, channel waveguides, buried channel waveguides, strip-loaded waveguides, wire waveguides, rib waveguides, diffused waveguides, slot waveguides, refractive index waveguides, step index waveguides, gradient index waveguides, printed waveguides, 3D printed waveguides, two photon printed waveguides, laser printed waveguides, deposition-based waveguides, glass waveguides, film-based waveguides, thin film waveguides, optical fibers, suspended waveguides, multimode waveguides, and single mode waveguides.

[0098] For enhanced performance and thermal management, the device may comprise multiple waveguides with separate laser diodes. For example, two consecutive waveguides can guide in the same direction, or towards each other, or away from each other. Benefits include improvedoptical efficiency through reduced propagation losses in shorter individual waveguides versus a single waveguide having the length of the congregate length of the shorter waveguides, reduced total optical power requirements, reduced electrical power consumption, and significant reduction in cooling requirements per laser diode.

[0099] More than one waveguide can operate parallel to each other. This may enhance closeness of cutting (shave), and limit nonlinear events and or lifetime of the waveguide.

[0100] For a predetermined waveguide of 1 dB / cm along the cutting region comprising a single waveguide length of 40-50 mm, splitting it into two shorter waveguides of half the length can improve propagation efficiency from 36% to 55% per waveguide. This reduces total optical power requirements from exemplary 3Wto approximately 2W, and total electrical power requirement by an electrooptically 35-40% efficient laser diode (now two) from 7.5W to approximately 4.9W, with subsequent cooling requirements per laser diode reduced from 4.5W to approximately 1.3W.

[0101] A device according to the present disclosure can comprise sophisticated power control systems to ensure safe operation. Laser power may be limited to control organic tissue (hair) temperature to a temperature chosen from the group of less than one of: 250°C, 200°C, 170°C, 150°C, 130°C, 120°C, 110°C, 100°C, 90°C, 80°C, 70°C, 65°C, 60°C, 55°C, or 50°C. Preferred temperature ranges include 60°C to 110°C, 60°C to 100°C, 60°C to 90°C, 60°C to 80°C, 60°C to 70°C, and 50°C to 80°C.

[0102] A device according to the present disclosure may comprise sensors for monitoring optical feedback signals, temperature measurements, cutting progress through detection of changes in guided light, retrograde light from organic tissue, fluorescence from organic tissue, attenuation of guided light in the waveguide, signal carried by backscatter from matter, signal carried by reflection from matter, signal carried by fluorescence from matter, and attenuated guided modes carrying signal information.

[0103] Power control may be achieved through MCU-mediated predetermined power settings, one or more pulses of light, one or more amplitudes of light, one or more power levels of light, one or more wavelengths of light, controlled exposure time of light, light quantum delivery, light quantum over predetermined light pulse or exposure time, predetermined properties of current or voltage to the laser light source, and optical sensor feedback derived power settings.

[0104] The laser may operate in continuous mode or pulsed mode with controlled parameters including parameters chosen from the group of: pulse width configured to heat organic tissue (hair) to specified temperature ranges, predetermined repetition rates, multiple predeterminedrepetition rates, tunable or variable repetition rates, repetition rates synchronized with varying shaving speeds, repetition rates adapted for varying organic tissue (hair) densities, repetition rates adapted for varying beard characteristics, pulsing cycles or pulsing modes, any number of sets of pulses, and numbers of pulses in sequences.

[0105] The laser may operate with a low laser power hair detection mode "simmer mode", and higher a power organic tissue (hair) cutting mode initiated by the simmer mode via signaling via a photo sensor such as a photo diode and onwards to the MCU.

[0106] The rate of continues mode or pulsing mode may be controlled by a motion sensor, proximity sensor, induction sensor, or an accelerometer.

[0107] The waveguide can provide selective light guiding based on precise refractive index relationships including zero coupling below a refractive index thresholds (e.g., n=1.52) - see FIG. 7, selective operation only with organic tissue (hair) having a refractive index of for example 1 .54 to 1.55 or higher - see FIG. 7, prevention of light guiding in materials with refractive indices lower than the organic tissue (hair), no light guiding in skin (n<1.41), and; no light guiding in water, oils, fats, lotions, soap, shampoo, dirt, or other contaminants - all of which have a refractive index n < 1.52 - see FIG. 7.

[0108] Materials specifically prevented from light guiding can include water, oil, fat, fatty acids, triglycerides, cholesterol, sebum, hair components, skin components, organic matter, inorganic dust matter, gels, liquids, dirt, dust, paste, soap, detergent, rubber, and silicone.

[0109] The cutting face of a cutting region of a waveguide according to the disclosure may comprise surface treatments including oleophobic coatings, hydrophobic coatings, lipophilic coatings, hydrophilic coatings, grafted surfaces, fluorinated silane treated surfaces, perfluorooctyltriethoxysilane, perfluoroalkyltrichlorosilanes, biphenyl-structured fluorinated silanes, short chain fluorinated silanes, tridecafluorooctyltrimethoxysilane, perfluorohexylethyltrimethoxysilane, fluorine-free coatings of silica nanotubes, structured SiO2 nanoparticle coatings, hexamethyldisilazane, methyl-terminated silanes, micro / nano surface texturing, hybrid organic-inorganic systems, sol-gel fluorinated hybrids, siloxane-based systems, nano-silica modified systems, fluorinated polymers, crosslinked fluorinated networks, perfluoropolyether-based coatings, UV-crosslinked fluoroacrylate systems, micro / nano structured surfaces, self-cleaning surfaces, and antireflective coatings.

[0110] A device according to the present disclosure can comprise protective elements including combs or teeth positioned in front of the waveguide, protection against mechanical impact andcontamination, predetermined, selectable, and / or tunable distance gauging from skin, maintained closeness perpendicular to skin, and distance gauging by protective combs.

[0111] The cutting face of a cutting region of a waveguide according to the disclosure can be configured to guide laser light in one or more predetermined chromophores in organic material including from the group of: hair integral lipid layer (ILL), keratin, water, melanin, pheomelanin, pigments, muscle tissue components, fat tissue components, connective tissue components, collagen, elastin, bone tissue components, cartilage tissue components, nerve tissue components, vascular tissue components, blood tissue components, hemoglobin, chlorophyll, plant tissue components, exogenous coatings, colorings, or pigmentations, and light absorbent materials added to organic material surfaces.

[0112] A device according to the present disclosure may be configured to affect or interact with organic tissues chosen from the group of: hair, skin, fat, muscle, cartilage, nails, bone, connective tissue, nervous tissue, lymphatic tissue, blood components, endothelial tissue, epithelial tissue, mesothelial tissue, nerve tissue, tissue emancipating from embryonic neural list, vascular tissue, leather, and plant tissue.

[0113] A device according to the present disclosure may perform functions chosen from abrasive device functions, denaturizing device functions, vaporizing device functions, scalpel functions, cauterizer functions, knife functions, scissors functions, plier functions, tongs functions, forceps functions, heater functions, warming device functions, cutter functions, shaver functions, grooming functions, and razor functions.

[0114] A device according to the present disclosure may be configured as chosen from the group of: scalpels, cauterizers, knives, swords, scissors, pliers, tongs, forceps, heaters, warmers, groomers, shavers, and razors.

[0115] In advanced embodiments, organic material (e.g., hair) becomes an integral component of the waveguide system when in optical contact with the top cladding of the original waveguide. The modes follow natural waveguide evolution through natural fundamental mode solutions, natural eigenmode characteristics, natural mode evolution, and natural mode distribution.

[0116] The transition occurs from confinement in the original waveguide (e.g., a planar waveguide comprising S1O2 claddings and a SiN core) to confinement in the organic material. The organic material acts as a second cladding or a new effective core until severed by heat due to material losses (absorption) and es (scattering) in the organic material (hair).

[0117] A device according to the present disclosure may be adapted or configured for guiding into organic tissue with guiding efficiency chosen from at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 99%, 0.1 % to 5%, 5% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 99%, and 95% to 100%. The waveguide may be configured to guide at least 1%, 10%, 50%, or more than 90% of the light on top of or outside the waveguide material.

[0118] The waveguide, waveguide core, and / or tissue affecting or interacting region may comprise optical resonator configurations including ring-resonator configurations and other resonator geometries for enhanced optical interaction.

[0119] A device according to the present disclosure may comprise light management systems including death mechanisms (e.g., death spirals) for quenching light not absorbed to the side of the waveguide, termination structures for light passing through the waveguide to its second end, sensor integration for measuring power and / or wavelength of transmitted / guided light, photo diode interfaces, and mode termination structures.

[0120] A device according to the present disclosure may be configured to provide bulbous terminations of organic material (e.g., organic tissue (hair)) upon severing. Control mechanisms include temperature increase and / or cooling parameters, time of temperature increase and / or cooling, electrical quantum characteristics delivered from electrical power source to light source, and predetermined dimensions of bulbous terminations.

[0121] A device according to the present disclosure may operate in hybrid modes where not all but only a portion of light utilizes diffraction or frustrated total internal reflection (FTIR), a remainder of light utilizes waveguide guiding along the waveguide, outside or on top of the waveguide, and combined external guiding and temporary integration approaches provide operational flexibility.

[0122] A device according to the present disclosure may be manufactured using processes including but not limited to CMOS (complementary metal-oxide-semiconductor) fabrication, BiCMOS (bipolar complementary metal-oxide-semiconductor) fabrication, other fabrication technologies, atomic layer deposition, vapor deposition, ion diffusion, laser printing, two-photon printing, multi-photon printing, 3D-printing, optical fiber pulling, etching, polymerization, and crystal growth.

[0123] A device according to the present disclosure can be implemented as a photonic integrated circuit (PIC) comprising edge coupler facets, nanometric silicon nitride waveguide cores, optimized bend radii (down to approximately 50pm minimum for minimal losses), window transitions by thinning the top cladding and narrowing the waveguide width to the cutting region section, thinned top cladding configurations for example along the cutting region, narrowed aspect ratios, integrated surface-mount photosensors, and mode termination structures.

[0124] The waveguide or its cutting region may be configured to be aimed substantially parallel to 60 degrees to skin or another surface and substantially perpendicular to 60 degrees to organic tissue (e.g., hair), or substantially perpendicular to 60 degrees to skin or another surface and substantially parallel to 60 degrees to organic tissue (e.g., hair). The device may comprise both waveguide configurations in parallel to each other, or other geometric combinations.

[0125] A device according to the present disclosure may comprise index matching materials between the waveguide or waveguide core and organic tissue (hair), with refractive indices between the waveguide / core and organic tissue (hair) or skin. Index matching materials may include liquids, gels, water, organic solvents, oils, esters, soap, detergents, fatty acids, cholesterol, lipids, polymers, dielectrics, and solids.

[0126] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0127] The terms “a,” “an,” “the” and similar referents used in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0128] Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0129] Certain embodiments are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, the present disclsoure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed unless otherwise indicated herein or otherwise clearly contradicted by context.

[0130] Furthermore, numerous references have been made to patents and printed publications throughout this specification. Each of the above-cited references and printed publications are individually incorporated herein by reference in their entirety.

[0131] In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the present invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations may be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.

Claims

What is claimed is:

1. A hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising: a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting hair, and wherein the optical waveguide configured such that electromagnetic modes of the light propagate guided by the waveguide outside the cutting face.

2. The hair cutting device of claim 1 , wherein the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided outside the cutting face.

3. A hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising: a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face for contacting hair, and wherein the optical waveguide is configured to accept hair as an integral component of the waveguide.

4. The hair cutting device of claim 2, wherein the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided in the hair when hair is accepted as an integral component of the waveguide.

5. A hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising: a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element that comprises an optical waveguide that is coupled to the light source to receive laser light, wherein a portion of a side wall of the optical waveguide forms a cutting face forcontacting hair, and wherein the optical waveguide is configured such that electromagnetic modes of the light propagate guided by the waveguide outside the cutting face, and wherein the optical waveguide is configured such that electromagnetic modes of the light propagate guided by the waveguide in hair when hair is in contact with the cutting face, and wherein the hair is an integral part of the waveguide.

6. The hair cutting device of claim 3, wherein the optical waveguide comprises a core comprising a thickness and cross-sectional aspect ratio, configured to control the percentage of laser light guided outside the waveguide material, and configured to control the percentage of laser light guided in the hair when hair is accepted as an integral component of the waveguide.

7. The hair cutting device of claims 1-3, wherein the waveguide is configured to establish optical contact with hair through at least one of: secondary cladding integration, effective core formation, and mode-guiding integration.

8. The hair cutting device of claims 1-3, wherein at least 10% of the laser light is guided outside the cutting face.

9. The hair cutting device of claims 1-3, wherein at least 50% of the laser light is guided outside the cutting face.

10. The hair cutting device of claims 1-3, wherein at least 90% of the laser light is guided outside the cutting face.

11. The hair cutting device of claims 1-3, wherein the optical waveguide comprises a core having a refractive index higher than the refractive index of hair.

12. The hair cutting device of claims 1-3, wherein the optical waveguide comprises a top cladding that comprises a thickness configured to control the percentage of laser light guided outside the cutting face.

13. The hair cutting device of claims 1-3, wherein the waveguide is configured to not emit radiant modes from the cutting face.

14. The hair cutting device of any of claims 1-3 wherein the optical waveguide is configured to prevent the laser light from guiding or coupling in materials having a refractive index of or below 1.52 outside the cutting surface.

15. The hair cutting device of any of claims 1-3, wherein the optical waveguide comprises a bottom cladding, or a core, or a top cladding, comprising a dimension selected from the group of a thickness, a width, a cross-sectional diagonal, and a diameter, that is chosen from the group of: less than 4 pm, 5 nm to 900 nm, or 1 m to 10um.

16. The hair cutting device of any of claims 1-3, further comprising at least one sensor configured to monitor optical feedback from hair.

17. The hair cutting device of any of claims 1-3, further comprising a power and control system configured to deliver laser light in pulses.

18. The hair cutting device of claims 1-3, wherein the optical waveguide is configured to operate without emission from the cutting face.

19. A method of cutting hair on a body of a subject, comprising guiding a light source for generating laser light at hair, wherein the wavelengths are corresponding to wavelengths absorbed by one or more chromophores in hair.

20. A method of cutting hair on a body of a subject, comprising guiding a light source for generating laser light in hair, wherein the wavelengths are corresponding to wavelengths absorbed by one or more chromophores in hair.

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