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[0025]The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
[0026]Embodiments described in the context of one of the methods or devices are analogously valid for the other methods or devices. Similarly, embodiments described in the context of a method are analogously valid for a device, and vice versa.
[0027]Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.
[0028]In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.
[0029]In the context of various embodiments, the phrase “at least substantially” may include “exactly” and a reasonable variance.
[0030]In the context of various embodiments, the term “about” as applied to a numeric value encompasses the exact value and a reasonable variance.
[0031]As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
[0032]As used herein, the phrase of the form of “at least one of A or B” may include A or B or both A and B. Correspondingly, the phrase of the form of “at least one of A or B or C”, or including further listed items, may include any and all combinations of one or more of the associated listed items.
[0033]Various embodiments may provide lighting or a lighting apparatus for façade applications using a waveguide (e.g., a polymer waveguide) and edge lighting.
[0034]Various embodiments may provide an alternative way of lighting by replacing the LED bars of prior art devices with a flexible light illuminating (optical) waveguide that may use one or more LEDs or one or more laser diodes (LDs) for edge lighting. The illuminating waveguide may have a solid form containing distributed scatterers or fluorophores to achieve uniform side illumination. Alternatively, the (optical) waveguide may have a hollow core in the centre with a reflecting or scattering plane in one or multiple sides of the waveguide. The light may propagate along the hollow core, and be reflected or scattered by the plane(s) for uniform side illumination. The inner wall(s) of the waveguide may be micro-patterned to enhance light scattering.
[0035]High power LEDs or LDs may be used as a light source. Hereinafter as described, LED may represent the light source used in various embodiments, but it should be appreciated that the LED may be replaceable with one or more LDs. In various embodiments, one or more LEDs may be located at or in the end facet(s) of the waveguide for edge lighting. The waveguide may be large enough for efficient coupling from the high power LED(s). The high power LED or LEDs in conjunction with the large size waveguide may ensure high luminance sufficient for façade lighting. If any of the LEDs fail, the LED chip could be individually accessed and replaced without disturbing the whole illuminating structure. Consequently, this may significantly cut down the maintenance cost, and also the electric bill, by reducing the number of LEDs compared to the known LED strip. In addition, the waveguide may be flexible, and may be produced in any arbitrary shape to fulfil any lighting need for façade lighting applications.
[0036]As described above and hereafter, in various embodiments, it may be possible to use a large waveguide with high power LED(s) or LD(s), which may scale up luminance beyond what the current illuminating waveguides can offer.
[0037]For façade lighting application, the known LED strip is the only product available in the current market. The LED strip suffers from the aforementioned issues, and end users are eager to find new technology to get away from the problems. It is possible to replace the LED strip with an illuminating waveguide with, for example, a high power LED (or LD) edge lighting, as described herein for various embodiments. If the edge lighting LED and/or the waveguide needs replacement, the individual component may be accessed for the maintenance. The waveguide may be fabricated by an extrusion technique, and the manufacturing cost is much cheaper than that for the LED strip. The extrusion technique is versatile and allows fabricating various geometries including circle, square, ribbon, polygonal shapes, etc. Also, the number of LEDs may be reduced by an order of magnitude without compromising the luminance compared to the known LED strip. Thus, various embodiments may substantially cut down the ownership cost.
[0038]Compared to the existing illuminating waveguide technologies, in various embodiments, it is possible to scale up the luminous efficacy sufficient for façade lighting application. This allows using a larger illuminating (optical) waveguide with scatterers or fluorophores properly positioned and compositionally optimised to enhance the luminance. The larger waveguide also permits the use of high power LEDs or LDs, for example, for edge lighting. The combination of the high power LEDs (or LDs), and the spatially and/or compositionally optimised scattering points may increase the luminous efficacy in the waveguide. Alternatively, the (optical) waveguide may have a hollow core in the centre to minimise absorption loss by the waveguide material itself. The hollow core waveguide may have a micro-pattern or reflecting layer on a surface of a wall(s) of the waveguide to efficiently scatter the light. Hence, the launched light from LEDs (or LDs) may be substantially or completely scattered and not be wasted by the waveguide material absorption. This may enhance the luminance in a large illuminating waveguide.
[0039]Further, there may be undesired strong light scattering at the LED coupling end of the waveguide. This scattering creates a bad impression of non-uniform illumination in a large scale lighting. To avoid or at least minimise the coupling scattering, it may be possible to include a LED coupling rig (as will be described further below as non-limiting examples with reference to FIG. 4A). The coupling rig may first capture the wide spreading emission of the LED by surrounding the LED with one or more reflective surfaces. The captured light may be directed to a collecting lens, and may be focused or collimated by the lens to the waveguide. The surrounding surfaces after the lens may be changed to or provided with one or more absorbing materials or absorbing regions to stop or minimise stray light from being scattered at the interface between the coupling rig and the waveguide. As a result, LED emission may be coupled to the waveguide with minimal or without the strong scattering effect, and any emission above the capturing angle of the lens may be absorbed by the surrounding surfaces in the coupling rig by the absorbing material(s)/region(s). Current technologies do not consider the scattering effect at the coupling ends.
[0040]The LED coupling rig and the waveguide may be separately installed at the construction sites or installation sites. This consideration is due to the rough handlings at the construction sites. The LED embedded waveguide designs in the prior art are too delicate to be installed during the architecture construction. Furthermore, the LED embedded waveguide requires trained expertise for installation as well as maintenance. Otherwise, the whole structure must be replaced just as for the current known LED bar. In contrast, the technique(s) in various embodiments provide a way or technology to allow individual access to the LED and/or the waveguide for easy installation and maintenance.
[0041]Various embodiments further provide methods of manufacturing the waveguide with an extrusion and a high temperature rolling technique, where details of the manufacturing processes would be described further below.
[0042]FIG. 1A shows schematic side views of a lighting apparatus 100a, 100b, according to various embodiments. The lighting apparatus 100a, 100b includes at least one light source 102a, 102b configured to provide a source light (represented by solid arrows 103a, 103b), an optical waveguide 104a, 104b optically coupled to the at least one light source 102a, 102b, the optical waveguide 104a, 104b having at least one input region 105a, 105b through which the source light 103a, 103b enters the optical waveguide 104a, 104b for propagation within the optical waveguide 104a, 104b, and a plurality of light interacting structures 106a, 106b arranged within the optical waveguide 104a, 104b, the plurality of light interacting structures 106a, 106b adapted to interact with the source light 103a, 103b to provide an illumination light (represented by dashed arrows 108a, 108b) emitted from the optical waveguide 104a, 104b to an ambient environment, wherein a concentration of the plurality of light interacting structures 106a, 106b increases, along a length portion 110a, 110b of the optical waveguide 104a, 104b, in a direction (represented by the arrows 125a, 125b) away from the at least one input region 105a, 105b.
[0043]In other words, a lighting apparatus 100a, 100b may be provided. The lighting apparatus 100a, 100b may include at least one light source 102a, 102b and an optical waveguide 104a, 104b optically coupled to one another so that the source light 103a, 103b generated by the at least one light source 102a, 102b is received by the optical waveguide 104a, 104b, where the source light 103a, 103b may then propagate in the optical waveguide 104a, 104b. The source light 103a, 103b may be transmitted from the at least one light source 102a, 102b into the optical waveguide 104a, 104b via at least one input region 105a, 105b of the optical waveguide 104a, 104b. This may mean that the at least one input region 105a, 105b is the point or region of entry of the source light 103a, 103b into the optical waveguide 104a, 104b. As a non-limiting example, the source light 103a, 103b may be arranged adjacent to the at least one input region 105a, 105b. While the at least one input region 105a, 105b is illustrated in FIG. 1A as an end region of the optical waveguide 104a, 104b, it should be appreciated that the at least one input region 105a, 105b may be at any part or portion of the optical waveguide 104a, 104b, including, for example, at a central portion of the optical waveguide 104a, 104b.
[0044]The optical waveguide 104a, 104b may be made of a transparent material, e.g., an optically transparent material. For example, the (optically) transparent material may be optically transmissive to an electromagnetic radiation of the visible light spectrum.
[0045]A plurality of light interacting structures 106a, 106b may be formed or disposed within the optical waveguide 104a, 104b. The source light 103a, 103b propagating within the optical waveguide 104a, 104b may be incident on the plurality of light interacting structures 106a, 106b. Interaction between the plurality of light interacting structures 106a, 106b and the source light 103a, 103b may occur so as to provide or generate an illumination light 108a, 108b that is emitted from the optical waveguide 104a, 104b to an ambient or surrounding environment to provide lighting. This may mean that the illumination light 108a, 108b is external to the optical waveguide 104a, 104b that illuminates the ambient environment.
[0046]As a non-limiting example, as a result of the interaction between the plurality of light interacting structures 106a, 106b and the source light 103a, 103b, the plurality of light interacting structures 106a, 106b may provide an intermediate light (such as the source light 103a, 103b that has been scattered and/or reflected by the plurality of light interacting structures 106a, 106b), from which the illumination light 108a, 108b may be emitted from the optical waveguide 104a, 104b to the ambient environment. The intermediate light may pass through a peripheral surface or side surface 112a, 112b of the optical waveguide 104a, 104b to form the illumination light 108a, 108b. This may mean that the illumination light 108a, 108b may be based on the intermediate light that is in turn produced in response to the interaction between the source light 103a, 103b and the plurality of light interacting structures 106a, 106b.
[0047]The plurality of light interacting structures 106a, 106b may be arranged such that a concentration (or distribution or density) of the plurality of light interacting structures 106a, 106b increases, along a length portion 110a, 110b of the optical waveguide 104a, 104b, in a (longitudinal) direction 125a, 125b away from the at least one input region 105a, 105b. The term “length portion” may mean a portion of the optical waveguide 104a, 104b over a length of the optical waveguide 104a, 104b. The length portion 110a, 110b may mean the portion of the optical waveguide 104a, 104b over the entire length or over a part of the length of the optical waveguide 104a, 104b.
[0048]In various embodiments, the plurality of light interacting structures 106a, 106b may be arranged with a concentration (or distribution or density) that increases, along the length portion 110a, 110b, in the (longitudinal) direction 125a, 125b away from the at least one input region 105a, 105b such that the illumination light 108a, 108b provides at least substantially uniform illumination over the length portion 110a, 110b. This may mean that the illumination light 108a, 108b that is emitted by the lighting apparatus 100a, 100b provides at least substantially uniform illumination over the length portion 110a, 110b. The uniform illumination may be in terms of uniform intensity or uniform luminance.
[0049]As may be appreciated, the intensity of the source light 103a, 103b generally may decrease in the direction 125a, 125b away from the at least one input region 105a, 105b through which the source light 103a, 103b enters the optical waveguide 104a, 104b. By having an arrangement of the plurality of light interacting structures 106a, 106b where the number, and hence the concentration, of the plurality of light interacting structures 106a, 106b, increases along the length portion 110a, 110b in the direction 125a, 125b, a higher number of the light interacting structures 106a, 106b are available to interact with the source light 103a, 103b at a part of the optical waveguide 104a, 104b where the intensity of the source light 103a, 103b may be lower as compared to another part of the optical waveguide 104a, 104b where the intensity of the source light 103a, 103b may be higher. In this way, the increased concentration of the plurality of light interacting structures 106a, 106b may compensate for the decreased intensity of the source light 103a, 103b by enabling a higher extraction efficiency of the source light 103a, 103b at the part of the optical waveguide 104a, 104b where the intensity of the source light 103a, 103b may be lower. Such an arrangement of the plurality of light interacting structures 106a, 106b may enable uniform illumination to be achieved. This may mean that at least substantially uniform illumination may be achieved as a result of the distribution profile of the plurality of light interacting structures 106a, 106b over the length portion 110a, 110b.
[0050]In various embodiments, the concentration of the plurality of light interacting structures 106a, 106b may increase along an entire length of the optical waveguide 104a, 104b. In various embodiments, such an arrangement may enable at least substantially uniform illumination to be provided over the entire length of the optical waveguide 104a, 104b.
[0051]In various embodiments, the concentration of the plurality of light interacting structures 106a, 106b along the length portion 110a, 110b may be provided based on an inverse relationship with the intensity of the source light 103a, 103b within the optical waveguide 104a, 104b. By having such a relationship, the illumination light 108a, 108b emitted from the optical waveguide 104a, 104b may provide at least substantially uniform illumination over the length portion 110a, 110b.
[0052]In various embodiments, generally, light may be transmitted or provided from within the optical waveguide 104a, 104b through the peripheral surface 112a, 112b of the optical wavelength 104a, 104b over the length portion 110a, 110b so as to provide the illumination light 108a, 108b. The peripheral surface 112a, 112b may be a side surface of the optical waveguide 104a, 104b. As a non-limiting example, the peripheral surface 112a, 112b may be a circumferential surface or part thereof of the optical waveguide 104a, 104b. The peripheral surface 112a, 112b of the optical waveguide 104a, 104b may be at least substantially transverse or orthogonal to at least one end facet 114a, 114b of the optical waveguide 104a, 104b. In this way, side illumination may be achieved.
[0053]In various embodiments, the source light 103a, 103b may enter the optical waveguide 104a, 104b via a single input region 105a, 105b.
[0054]In the context of various embodiments, the source light 103a, 103b may include an electromagnetic radiation including, but not limited to, the visible light spectrum, the ultraviolet region or the infrared region. For example, the source light 103a, 103b may have a wavelength of between about 400 nm and about 700 nm.
[0055]In the context of various embodiments, the illumination light 108a, 108b may include an electromagnetic radiation including or consisting of the visible light spectrum (e.g., a wavelength of between about 400 nm and about 700 nm).
[0056]In various embodiments, a concentration (or distribution or density) of the plurality of light interacting structures 106a, 106b may increase in a transverse direction (or cross-sectional direction) from an outer region of the optical waveguide 104a, 104b to an inner region of the optical waveguide 104a, 104b. The outer region of the optical waveguide 104a, 104b may mean a region proximal to the perimeter or boundary of the optical waveguide 104a, 104b, while the inner region of the optical waveguide 104a, 104b may mean a central region of the waveguide 104a, 104b or a region proximal to the central axis of the optical waveguide 104a, 104b. As an example, the transverse direction may be a radial direction.
[0057]In various embodiments, the concentration of the plurality of light interacting structures 106a, 106b in the transverse direction may follow a Gaussian profile (or distribution) or a parabolic profile (or distribution) or a top-hat profile (or distribution).
[0058]As may be appreciated, the intensity or beam profile of the source light 103a, 103b within the optical waveguide 104a, 104b generally may be higher at the inner region of the optical waveguide 104a, 104b (e.g., the intensity increases from the outer region of the optical waveguide 104a, 104b to the inner region of the optical waveguide 104a, 104b). By having an arrangement of the plurality of light interacting structures 106a, 106b where the number, and hence the concentration, of the plurality of light interacting structures 106a, 106b, increases in the transverse direction from the outer region to the inner region, a higher number of the light interacting structures 106a, 106b are available to interact with the source light 103a, 103b at the inner region of the optical waveguide 104a, 104b where the intensity of the source light 103a, 103b may be higher so as to achieve a higher extraction efficiency of the source light 103a, 103b from the inner region of the optical waveguide 104a, 104b.
[0059]In various embodiments, the at least one light source 102a, 102b and the optical waveguide 104a, 104b may be physically connected to each other.
[0060]In various embodiments, the at least one light source 102a, 102b and the optical waveguide 104a, 104b may be separably connected to each other. This may mean that the at least one light source 102a, 102b and the optical waveguide 104a, 104b may be separate entities or separate units (e.g., separately manufactured) which may then be assembled or connected to each other. In this way, for example, when the at least one light source 102a, 102b or the optical waveguide 104a, 104b becomes faulty, the corresponding faulty item or unit may be separately replaced.
[0061]In various embodiments, the at least one input region 105a, 105b may include at least one end region of the optical waveguide 104a, 104b. In various embodiments, the at least one input region 105a, 105b may include at least one end facet 114a, 114b of the optical waveguide 104a, 104b. This may mean that the source light 103a, 103b may enter the optical waveguide 104a, 104b through the at least one end facet 114a, 114b. In this way, the at least one light source 102a, 102b may provide edge lighting to the optical waveguide 104a, 104b.
[0062]In various embodiments, the at least one light source 102a, 102b may be (separably) connected to the at least one end facet 114a, 114b of the optical waveguide 104a, 104b.
[0063]In various embodiments, the lighting apparatus 100a, 100b may include two light sources (e.g., one of which may be the light source 102a, 102b) respectively arranged at (or connected to) opposite end facets (e.g., one of which may be the end facet 114a, 114b) of the optical waveguide 104a, 104b, the two light sources configured to provide the source light 103a, 103b, and wherein the concentration of the plurality of light interacting structures 106a, 106b may increase, along the length portion 110a, 110b of the optical waveguide 104a, 104b, in a respective (longitudinal) direction away from each of the opposite end facets. By having such an arrangement of the plurality of light interacting structures 106a, 106b, with the concentration of the plurality of light interacting structures 106a, 106b increasing in the respective (longitudinal) direction away from each of the opposite end facets, the illumination light 108a, 108b may provide at least substantially uniform illumination over the length portion 110a, 110b. The concentration of the plurality of light interacting structures 106a, 106b may increase, from each of the opposite end facets, towards a central portion of the optical waveguide 104a, 104b. In this way, the concentration of the plurality of light interacting structures 106a, 106b may reach a maximum at the central portion of the optical waveguide 104a, 104b. In various embodiments, the concentration of the plurality of light interacting structures 106a, 106b along the length portion 110a, 110b may follow a Gaussian profile (or distribution) or a parabolic profile (or distribution) or a top-hat profile (or distribution). In various embodiments, each light source of the two light sources may include a light source unit or a plurality of light source units (e.g., an array of light source units), where each light source unit may be a light emitting diode (LED) or a laser diode (LD).
[0064]In various embodiments, the optical waveguide 104a, 104b, may further include a (light) diffusion layer. The diffusion layer may diffuse light to promote even or uniform illumination. The diffusion layer may be arranged over the length portion 110a, 110b of the optical waveguide 104a, 104b. The diffusion layer may be provided on an outer surface or the peripheral surface 112a, 112b. The diffusion layer may at least substantially surround the optical waveguide 104a, 104b, for example, around the entire perimeter of the optical waveguide 104a, 104b.
[0065]In various embodiments, the lighting apparatus 100a, 100b may further include a coupling assembly (or coupling jig) connected to the optical waveguide 104a, 104b, the at least one light source 102a, 102b being received in the coupling assembly. The coupling assembly may be separably connected to the optical waveguide 104a, 104b. The coupling assembly may be connected at the at least one input region 105a, 105b.
[0066]In various embodiments, the coupling assembly may include a housing to receive the at least one light source 102a, 102b, the housing having at least one reflective inner surface to reflect the source light 103a, 103b towards the optical waveguide 104a, 104b.
[0067]The housing may have an internal hollow or solid structure. The at least one reflective inner surface may include a mirror or a metallic reflector layer.
[0068]The source light 103a, 103b may be emitted by the at least one light source 102a, 102b over a large or wide angle and by providing the housing with the at least one reflective inner surface, most or all of the source light 103a, 103b may be reflected by the at least one reflective inner surface towards the optical waveguide 104a, 104b. In various embodiments, all inner surfaces of the housing may be reflective. This may mean that the at least one light source 102a, 102b may be surrounded (on all sides) by reflective surfaces.
[0069]In various embodiments, the coupling assembly may further include at least one light absorption region arranged proximal to the at least one input region 105a, 105b of the optical waveguide 104a, 104b. The at least one light absorption region may absorb light, for example, any stray light that may be present. For example, the at least one light absorption region may minimise or prevent stray light from being scattered at an intermediate region between the coupling assembly and the optical waveguide 104a, 104b, for example, at an interface between the coupling assembly and the optical waveguide 104a, 104b. The at least one light absorption region may be arranged between the at least one light source 102a, 102b and the at least one input region 105a, 105b of the optical waveguide 104a, 104b. In this way, the at least one light source 102a, 102b may be arranged distal to the at least one input region 105a, 105b.
[0070]In various embodiments, the coupling assembly may further include an optical lens (or collecting lens) to focus or collimate the source light 103a, 103b into the optical waveguide 104a, 104b. The optical lens may be arranged prior to the at least one light absorption region. In this way, the at least one light absorption region may minimise or prevent stray light from being scattered at an intermediate region between the coupling assembly and the optical waveguide 104a, 104b (e.g., at an interface between the coupling assembly and the optical waveguide 104a, 104b). Further, the at least one light absorption region may absorb any emission or light that may be incident on the lens at an angle above the capturing angle of the lens, and which therefore may not be focused by the lens into the optical waveguide 104a, 104b, resulting in stray light.
[0071]In various embodiments, the lighting apparatus 100a, 100b may further include a locking mechanism to secure the coupling assembly to the optical waveguide 104a, 104b. The locking mechanism may include complementary structures that cooperate or mate to secure the coupling assembly and the optical waveguide 104a, 104b to one another. The complementary structures may be respectively provided at the coupling assembly and at the optical waveguide 104a, 104b. The locking mechanism may include a thread-type mechanism, a click-type mechanism or a snap fit-type mechanism.
[0072]In the context of various embodiments, the at least one light source 102a, 102b may include at least one light emitting diode (LED) or at least one laser diode (LD).
[0073]In the context of various embodiments, the at least one light source 102a, 102b may have a lumen rating of between about 200 lm (lumen) and about 2000 lm, for example, between about 200 lm and about 1000 lm, between about 200 lm and about 500 lm, between about 500 lm and about 2000 lm, between about 1000 lm and about 2000 lm, or between about 500 lm and about 1500 lm. Therefore, at least one high lumen or high power light source may be used.
[0074]In the context of various embodiments, the optical waveguide 104a, 104b may be at least substantially flexible.
[0075]In the context of various embodiments, the optical waveguide 104a, 104b may be made of a material suitable for extrusion. In this way, the optical waveguide 104a, 104b may be formed via an extrusion process.
[0076]In the context of various embodiments, the optical waveguide 104a, 104b may be made of a polymer, a resin or a thermoplastic. It should be appreciated that each of the polymer, resin or thermoplastic may be (optically) transparent. The use of resins or thermoplastics as the waveguide material may be suitable for forming the optical waveguide via a sol-gel process or a 3D printing process.
[0077]In the context of various embodiments, the optical waveguide 104a, 104b may have a cross sectional dimension of between about 1 mm and about 20 mm, for example, between about 1 mm and about 10 mm, between about 1 mm and about 5 mm, between about 5 mm and about 10 mm, between about 5 mm and about 20 mm, or between about 10 mm and about 20 mm. In this way, a large size optical waveguide may be provided. A large size optical waveguide may allow the lighting apparatus 100a, 100b to provide a high luminance as the amount of the source light 103a, 103b coupled into the optical waveguide 104a, 104b may be proportional to the size or volume of the optical waveguide 104a, 104b, and, consequently, the luminance of the resulting illumination light 108a, 108b may be higher. The term “cross sectional dimension” may mean the longest straight-line distance between two points of the boundary (e.g., circumference, perimeter, etc.) of the cross-section.
[0078]In the context of various embodiments, the length portion 110a, 110b of the optical waveguide 104a, 104b may be at least 0.5 m. (i.e., ≥0.5 m), e.g., at least 1 m, at least 2 m or at least 5 m.
[0079]In the context of various embodiments, the optical waveguide 104a, 104b may include a cylindrical waveguide, a rod waveguide or a planar waveguide (e.g., in the form/shape of a ribbon or a sheet).
[0080]In the context of various embodiments, the optical waveguide 104a, 104b may have a cross-sectional shape of a circle, an ellipse, a rectangle, a square, or a triangle. However, it should be appreciated that the optical waveguide 104a, 104b may have any suitable cross-sectional polygonal shape.
[0081]In the context of various embodiments, the lighting apparatus 100a, 100b may be configured to provide the illumination light 108a, 108b having a luminance of between about 1000 cd (candela) and about 10000 cd, for example, between 1000 cd and about 5000 cd, between 1000 cd and about 3000 cd, between 5000 cd and about 10000 cd, or between 3000 cd and about 5000 cd.
[0082]For ease of understanding, the lighting apparatus 100a will now be used to illustrate various embodiments having an optical waveguide with a solid core region (e.g., a “solid core waveguide”). In various embodiments, the optical waveguide 104a may include a solid core region, and the plurality of light interacting structures 106a may be arranged within the solid core region. The source light 103a may propagate within the solid core region. The optical waveguide 104a may be free of a cladding. In various embodiments, the optical waveguide 104a having the solid core region may provide a 360° illumination.
[0083]The number of the plurality of light interacting structures 106a increases in the (longitudinal) direction 125a away from the at least one input region 105a. Such an arrangement of the plurality of light interacting structures 106a results in the concentration of the plurality of light interacting structures 106a increasing in the direction 125a away from the at least one input region 105a.
[0084]The plurality of light interacting structures 106a may include at least one of scatterers