Systems and methods for optical beam combining

Abstract

It concerns devices and systems for optical amplification by combining multiple beams emanating from multiple sources, such as multiple optical fibers. A method for combining multiple optical beams includes at least the steps of providing a first set of coherent beam combining (CBC) devices, and combining directed combined output optical beams output by the first set of CBC devices with at least one additional combining device, and further includes at least the steps of outputting a single combined final output optical beam and directing it externally from the at least one additional combining device.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure generally relates to systems and methods for combining multiple optical beams. [Background technology]

[0002] Optical amplifiers are widely used in many systems for an increasing number of industries and applications, especially in systems requiring high power laser output.

[0003] An optical amplifier is a device or system that allows for the amplification of an optical signal by using optical equipment and / or elements without the need to convert the optical signal to be amplified into a non-optical signal, such as an electrical signal, and then convert it back to an optical signal. Some methods for optical amplification include doped fiber amplification (DFA), in which one or more doped optical waveguides, such as double-clad doped optical fiber, are used for power scaling of the optical input. One type of DFA includes a fiber laser, which uses a doped optical fiber as the gain medium. [Brief explanation of the drawings]

[0004] These figures illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in this document.

[0005] For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity of presentation. Additionally, reference numerals may be repeated among the figures to indicate corresponding or similar elements. Reference to previously presented elements is implied without necessarily further reference to the drawing or description in which they appear. The figures are as follows:

[0006] [Figure 1] 1 shows the setup for the background technique of coherent beam synthesis. [Figure 2]1 illustrates a general layout of a coherent beam combining system for combining multiple optical beams emanating from multiple optical fibers, including a monolithic body and an optical element having a phase mask, according to some embodiments. [Figure 3A] FIG. 1 shows a diagram illustrating the general optical effect of a beam splitter to show how the beam splitter can be used as a diffractive optical element, according to some embodiments. [Figure 3B] FIG. 1 shows a diagram illustrating a cross-sectional etching pattern of an exemplary beam splitter phase mask. [Figure 3C] The phase mask given in FIG. 3B shows the higher order side lobes of the beam split by the beam splitter. [Figure 4] 1 illustrates a general layout of a coherent beam combining system for combining multiple optical beams emanating from multiple optical fibers comprising a monolithic body with a phase mask embedded on its output face, according to some embodiments. [Figure 5] 1 illustrates a coherent beam combining system using a monolithic body with a lens-shaped output surface and separated (non-combining) optical elements, according to some embodiments. [Figure 6] 1 illustrates a coherent beam combining system using a monolithic body with an internal reflective surface and a phase mask etched, embossed, or glued onto its output face, according to some embodiments. [Figure 7] 1 illustrates a coherent beam combining system using a monolithic body with a curved input face and a phase mask etched, embossed, or glued onto its output face, according to some embodiments. [Figure 8] 1 illustrates a coherent beam combining device including a monolithic body having a graded refractive index configuration, according to some embodiments. [Figure 9] 1 illustrates a system for coherent beam combining having multiple beam combining devices, according to some embodiments. [Figure 10A] 1 shows a background art optical setup for spectral beam combining using a single grating element. [Figure 10B] 1 shows a background art optical setup for spectral beam combining using two grating elements. [Figure 11] 1 illustrates a spectral beam combining device using a monolithic body with a single diffractive surface and a parallel reflective surface, according to some embodiments. [Figure 12] 1 illustrates a spectral beam combining device using a monolithic body with a single diffractive surface and an angled reflective surface relative thereto, according to some embodiments. [Figure 13] 1 illustrates a spectral beam combining device using a monolithic body with a single diffractive surface and multiple reflective surfaces, according to some embodiments. [Figure 14] 1 illustrates a system for spectral combining of spectrally differentiated optical beams emanating from multiple coherent beam combining devices, according to some embodiments. [Figure 15] 1 illustrates a flowchart of a method for coherent beam combining, according to some embodiments. [Figure 16] 1 illustrates a flowchart of a method for spectral beam combining, according to some embodiments. [Figure 17] 1 illustrates a flowchart of a method for cascaded beam combining, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0007] Aspects of the disclosed embodiments relate to devices and systems for optical amplification by combining multiple beams emanating from multiple light sources, such as multiple optical fibers.

[0008] Fiber lasers used as optical amplifiers for power scaling use one or more optical fibers, such as doped optical fibers (also referred to as "doped fibers"), as the gain medium. The beam quality and / or maximum gain power of a fiber laser's output beam can be subject to several physical effects, such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and / or modal thermal instability. These effects can limit the physical characteristics of the fiber laser output beam, such as limiting the output beam quality and / or maximum output beam power.

[0009] The term "doped optical fiber" refers to any type of optical fiber that is doped with one or more elements, such as, but not limited to, erbium, dysprosium, ytterbium, neodymium, thulium, praseodymium, and / or holmium.

[0010] The terms "optical beam" or "beam" as used herein (interchangeably) may refer to any propagating electromagnetic signal, field, and / or wave in the optical wavelength range.

[0011] The term "beam quality" may refer to any one or more beam characteristics, such as, but not limited to, wavefront (profile) quality, beam waste, beam radius, beam divergence, beam intensity / amplitude, beam brightness level (brilliance), phase deviation (phase coherence), etc., and / or maintenance of these beam characteristics over time and / or distance.

[0012] To overcome some of the limiting physical effects in fiber lasers or other DFA-based devices and systems, such as limitations on output power and / or near-diffraction beam quality, or to improve at least power scaling and / or beam quality, beam combining can be used, which involves combining multiple optical beams, optionally emanating from several optical waveguides (core-doped or any other type of optical fiber), into a single optical beam.

[0013] Two beam combining techniques can be used: spectral beam combining (SBC) and coherent beam combining (CBC).

[0014] SBC can generally be described as the combination of multiple beams emanating from multiple beam sources, where the beams are of different wavelengths (e.g., non-overlapping or partially overlapping wavelength bands). For SBC, the layout of the optical elements used for the combination (i.e., the spectral combiner device or spectral combiner) should be configured to allow all beams to ultimately propagate at its output in the same propagation direction to form a wavelength-sensitive, broadband output beam propagated in a single, unified outward direction. SBS devices can be configured to preserve the wavelengths of all input beams.

[0015] CBC may generally be described as a method for combining coherent optical beams having similar, overlapping, or identical wavelengths or narrow bands of wavelengths to output a coherent narrowband output beam propagating in a single unified outward direction (e.g., power-scaled), e.g., by controlling the phase of the input beams to obtain constructive interference at the output. In CBC, at the input, the coherent optical beams may have (substantially) identical phase.

[0016] FIG. 1 shows an optional layout of a background art CBC optical system 10 for combining multiple beams (which may be coherent, i.e., of similar, identical, or overlapping wavelengths) emanating from multiple optical fibers 11a, 11b, and 11c, with a collimating lens 12 for focusing the beams onto a single focal plane where a diffraction grating element (DOE) 13 is positioned to combine the collimated beams into a single combined output beam 15. The elements of this CBC optical system 10, namely, the lenses 12, the fibers 11a-11c, and the DOE 13, are all spaced apart from one another and therefore require each element to be held in place for their alignment while spaced apart. This configuration is highly sensitive to physical instabilities, as it requires a high level of alignment between all optical elements of the CBC optical system 10 to generate and maintain high output beam quality. Any movement, such as slight wobble of the lens 12, the DOE 13, and / or displacement of the output faces of the optical fibers 10a-10c relative to one another, can affect the overall combining process and quality.

[0017] Aspects of the disclosed embodiments relate to a beam combining device for coherent beam combining of multiple optical beams (herein "incident beams") emanating from multiple optical fibers including at least a monolithic body and a phase mask configured for CBC of the incident beams to form a single combined optical beam (herein "output beam") output therefrom.

[0018] According to some embodiments, the monolithic body may be configured to focus all incident beams to a single focal point, and the phase mask may be positioned on a plane containing the focal point. For example, the monolithic body may be configured such that incident beams directed therethrough converge at the focal point at the same exit separation angle as each other, the separation angle and the focal point defining a focal plane on which the phase mask is positioned.

[0019] The phase mask may be an integral part of the monolithic body or may be embedded in a separate optical element. If a separate optical element is used, the monolithic body may be configured such that the focal point and focal plane are outside it, or if integrated on at least one side of the monolithic body, the optical element with the phase mask embedded therein may be positioned separate from and outside the monolithic body if the focal plane is located on one side of the monolithic body.

[0020] Embodiments of the disclosed CBC devices are designed to provide improved stability of each CBC device component relative to one another to reduce or prevent reduction in output beam quality caused by relative physical movement between at least some of the CBC device components. Other advantages of the disclosed CBC devices may include allowing an increased number of optical fibers to be used, thus increasing gain (output power), while maintaining high output beam quality.

[0021] For example, in some embodiments, relative movement between the monolithic body and the plurality of optical fibers can be reduced or prevented by fixedly connecting the optical fibers to the monolithic body, for example, by welding, fusing, splicing, or any other form of fixed connection of the fibers to the monolithic body.

[0022] Additionally or alternatively, the monolithic body may be designed to incorporate one or more collimating lenses as an integral part of the monolithic body to prevent relative movement therebetween. Additionally or alternatively, the OE(s) of the CBC device may be integrally or non-integrally (and even, for example, fixedly) attached to the output face of the monolithic body to prevent relative movement therebetween.

[0023] CBC devices can also be specifically designed to accommodate the number of incident beams, their separation angle, and one or more properties of each of the incident beams, such as wavelength, wavelength band, phase, amplitude, polarization, beam radius, beam coherence, etc.

[0024] According to some embodiments, each optical fiber may be operatively associated (e.g., connected) at its input end to a light source, thereby outputting guided light from its output end. The beam of light output from the output end of the optical fiber may be referred to as an incident beam, since it is incident on the monolithic body.

[0025] According to some embodiments, the monolithic body may be a three-dimensional (3D) object that is at least partially transparent and has at least an input face and an output face. The input face may be configured to fixedly connect (e.g., by fusing, welding, slicing, gluing, etc.) to a plurality of optical fibers, and the geometry of the monolithic body may be configured to direct a plurality of incident beams of light from the plurality of optical fibers toward its output face.

[0026] According to some embodiments, optical fiber connections to the input face of the monolithic body may define "engagement spots," which may be points or areas on the input face of the monolithic body that engage with the output ends of the optical fibers. The connection or engagement between the output ends of the optical fibers and the input face of the monolithic body creates (substantially) equal spacing between each pair of adjacent engagement spots, allowing incident beams to be incident on the monolithic body at a particular desired angle of incidence (e.g., with respect to the major axis) such that the relative angle between each pair of adjacent beams (defined as the "incident separation angle") is equal for each pair of adjacent beams, i.e., the incident beams enter the monolithic body through the input face at equal "incident separation angles."

[0027] According to some embodiments, the monolithic body may be configured so that the beams directed thereby exit its output surface at the same exit separation angle from each other, and the phase mask may be designed to correspond to the exit separation angle of the exit beams.

[0028] According to some embodiments, an optical fiber fixedly connected to the input face of the monolithic body may be an integral part of the beam combining device.

[0029] The optical fiber may be a doped optical fiber and / or may be double clad.

[0030] According to some embodiments, the monolithic body has one or more additional surfaces other than the input and output surfaces.

[0031] According to some embodiments, the input or output surface may be curved, concave, or flat (as well as straight).

[0032] As used herein, the term "surface" may refer to a surface of any type or shape, such as a flat surface, a curved surface, etc.

[0033] According to some embodiments, the input face of the monolithic body may be smoothed (polished) to improve the engagement between the input face and the output end of the optical fiber connected to it.

[0034] The monolithic body can be made from any transparent or partially transparent material such as glass, silica fused glass, acrylic glass, and the like.

[0035] According to some embodiments, the monolithic body may be made from a transparent material of a single index of refraction.

[0036] According to other embodiments, the monolithic body may be made of a fully or partially transparent material having one or more refractive indices, for example, by having a gradient indexing or by having an indexing that varies discretely over different areas (volumes) of the monolithic body.

[0037] According to some embodiments, the properties of the monolithic body, such as its geometry, dimensions, refractive indexing, transparency and rate of transparency, shape, and dimensions, can be designed and adapted to direct an incident beam from its input face toward its output face in a specific manner so that the output beam exits the output face at a desired exit angle relative to the major axis (e.g., to accommodate the exit separation angle required by the phase mask design) and / or converge to focus the incident beam to a single focal point. The properties of the monolithic body can be adapted depending on how the optical fiber engages with the inner surface, the properties of the incident beam, e.g., wavelength, beam dispersion, etc., the entrance separation angle, and the properties of the phase mask, e.g., phase mask profile, positioning relative to the output face, size, and dimensions, etc.

[0038] 2, a CBC system 1000 for combining multiple optical beams emitted from multiple optical fibers is shown in accordance with some embodiments. The CBC system 1000 may include a beam combining device 1100, multiple light sources such as light sources 1200a, 1200b, 1200c, and 1200d, and multiple optical fibers such as optical fibers 1300a, 1300b, 1300c, and 1300d, each of which may be fixedly connectable to the beam combining device 1100 and be an integral part thereof.

[0039] According to some embodiments, the beam combining device 1100 may include a monolithic body 1110 and one or more optical elements, such as an optical element (OE) 1120 having a phase mask, for example, by having a phase mask etched, engraved, embossed, or glued onto one side (surface) of the OE 1120.

[0040] The monolithic body 1110 may be a 3D fully transparent or partially transparent element having an input surface 1111A and an output surface 1111B (sides). The monolithic body 1110 may be configured to direct an incident optical beam of light (herein "incident beam") that is output from the output ends of the optical fibers 1300a-1300d and enters the monolithic body 1110 at its input surface 1111A toward the output surface 1111B. The OE 1120 may be combined with the output surface 1111B of the monolithic body 1110 or may be located a short distance from the output surface 1111B of the monolithic body 1110 (i.e., in a non-combining position) and configured to combine an optical beam (herein "output beam" or "output optical beam") that exits the output surface 1111B. The features of the OE 1120, such as the diffractive configuration, the design of the diffractive surface(s), the dimensions and distance from the output face 1111B of the monolithic body 1110, etc., may be designed to achieve optimal beam combining and may correspond to the design of the monolithic body 1110 and the beam characteristics of each of the incoming and / or outgoing beams, i.e., the characteristics of the beam when incident on the input face 1111A, such as wavelength, wavelength band, beam radius, beam dispersion, beam power, amplitude, polarization, etc.

[0041] The beam characteristics of the output beam may be related to (ie, dependent on) the beam characteristics of the input beam (output by the optical fiber), as well as the configuration of the monolithic body and the way the optical fiber is connected to its input face.

[0042] For each CBC system 1000, the characteristics of the incoming and / or outgoing beams can be known in advance so that the design of the monolithic body 1110 and / or OE 1120 and / or their relative positioning can be arranged for each CBC system requirement and feature.

[0043] According to some embodiments, each optical fiber 1300a, 1300b, 1300c, or 1300d may direct light originating from a respective light source 1200a, 1200b, 1200c, or 1200d, for example, by connecting the input end 1301a, 1301b, 1301c, and 1301d of each of optical fibers 1300a, 1300b, 1300c, and 1300d to the output of a respective light source 1200a, 1200b, 1200c, or 1200d. For example, optical fiber 1300a may direct light originating from light source 1200a, etc.

[0044] Each of the light sources 1200a-1200d used may include at least one light-emitting device, such as a laser device and / or a light-emitting diode (LED), configured to emit light of the same, overlapping, or single wavelength or wavelength band. Each optical fiber 1300a, 1300b, 1300c, or 1300d may be configured to direct light according to the specific characteristics of the light output by its respective light source 1200a, 1200b, 1200c, or 1200d, such as a specific narrow wavelength band or wavelength and / or a specific light source output power, as well as according to a specific gain objective. Each of the optical fibers 1300a-1300d may optionally be a doped fiber with a double cladding.

[0045] Each optical fiber 1300a, 1300b, 1300c, or 1300d may be fixedly connected to input face 1111A of monolithic body 1110 at a respective output end 1302a, 1302b, 1302c, or 1302d, thereby defining a respective engagement spot 1101a, 1101b, 1101c, or 1101d, which is defined as a volume, area, or point of (fixed) engagement between the output end of the optical fiber and input face 1111A. Each optical fiber 1300a, 1300b, 1300c, or 1300d may be fixedly connected to input face 111A of monolithic body 1110, for example, by splicing, welding, gluing, fusing, and / or via an optical connector or node.

[0046] The OE 1120 may be designed and positioned to combine the beams (herein referred to as the "exit beam") exiting the output face 1111B of the monolithic body 1110 and output a combined beam 1500, which may be a power-scaled beam that maintains the original narrow / single wavelength band of all the incident beams.

[0047] The OE 1120 may include a phase mask configured to manipulate or shape a beam of light, for example, by inducing a local phase change. The OE 1120 may include a phase mask 1121 with a phase pattern configured for CBC, for example, by causing reverse beam diffraction. One example for an OE 1120 phase mask 1121 design that can be used for CBC is one that functions as a reverse beam splitter.

[0048] A beam splitter is a diffractive OE containing a phase mask configured to split a single incident beam into several beams with equal separation angles, where the number of beams N resulting from the beam splitting is defined as the "order" of the beam splitter. A beam splitter OE 1120 arranged in a counter-orientation can be used for beam combining.

[0049] According to some embodiments, the structure of the beam splitter OE 1120 can be made from an optical substrate (typically glass, e.g., fused silica glass) onto which a periodic phase pattern can be etched. The surface of the phase mask can be reflective or clear, and the combining effect of the OE 1120 can be achieved by having beams pass through or reflect from it. The phase pattern can be periodic, and the number of beams N input to the OE 1120 (splitting order) and / or separation angle can determine the design of the periodic pattern of the phase mask 1121 of the OE 1120.

[0050] 3A shows an example way in which a beam splitter can be inverted to function as a beam combiner. On the left, incoming optical beam 320A is directed toward beam splitter 310A, which is designed to split incoming optical beam 320A into multiple output optical beams 301 a, 302 a, 303 a, 304 a, and 305 a. Output optical beams 301 a, 302 a, 303 a, 304 a, and 305 a are separated from one another by equal separation angles α (alpha). By using beam splitter element 310B having the same phase mask pattern and design as beam splitter 310A and inputting multiple input beams 301b, 302b, 303b, 304b, and 305b spaced apart by the same separation angle α (alpha) and having beam characteristics such as wavelength as output beam α (alpha), beam splitter element 310B combines input beams 301b, 302b, 303b, 304b, and 305b into a single combined output beam 320B, which can maintain the same wavelength(s) of the incoming input beams 301b, 302b, 303b, 304b, and 305b.

[0051] Figure 3B shows an example diagram of the cross-sectional pattern of a beam splitter's phase mask. The relative thickness and depth of the etching created on one side of the OE includes a repeating phase mask that determines how the beam diffracts as it exits the mask. In this case, it splits into five main beams and several higher-order beam side lobes, as seen in Figure 3C. The efficiency of the OE can be determined by dividing the power of the main orders by the total power. The separation angle between the output beams (peaks in the graph) can be determined by the characteristics of the period in the phase mask (e.g., the spacing between peaks). In this example, the period length is 200 μm (micrometers), and the resulting separation angle is 0.005 Rad. Reducing the period length increases the separation angle, and vice versa.

[0052] In coherent beam combining, a beam splitter OE can be inverted by combining N beams separated by equal separation angles into a single combined output beam. This effect can be achieved by reversing the effect of a diffractive OE and replicating the N beams only in the opposite direction, at the precise separation angle corresponding to the particular OE phase mask design, so that they are incident on the OE rather than emerging from it (as shown in Figure 3A).

[0053] 4 shows a general layout of a CBC system 4000 for combining multiple optical beams, according to some embodiments. The CBC system 4000 may include multiple light sources, such as light sources 4200a, 4200b, 4200c, and 4200d, multiple optical fibers, such as optical fibers 4300a, 4300b, 4300c, and 4300d, and a beam combining device 4100 including a monolithic body 4110 having a phase mask 4112 embedded or integrally connected to its output face 4111B.

[0054] According to some embodiments, each optical fiber 4300a, 4300b, 4300c, or 4300d may direct light originating from a respective light source 4200a, 4200b, 4200c, or 4200d, for example, by connecting the input end 4301a, 4301b, 4301c, and 4301d of each of the optical fibers 4300a, 4300b, 4300c, and 4300d to the output of the respective light source 4200a, 4200b, 4200c, or 4200d. For example, optical fiber 4300a may direct light originating from light source 4200a, etc.

[0055] Each of the light sources 4200a-4200d used may include at least one light-emitting device, such as a laser device and / or a light-emitting diode (LED), configured to emit light of the same, overlapping, or single wavelength or wavelength band. Each optical fiber 4300a, 4300b, 4300c, or 4300d may be configured to direct light according to the specific characteristics of the light output by its respective light source 4200a / 4200b / 4200c / 4200d, such as a specific narrow wavelength band or wavelength and / or a specific light source output power, as well as according to a specific gain objective. Each of the optical fibers 4300a-4300d may optionally be a doped fiber with a double cladding.

[0056] Each optical fiber 4300a, 4300b, 4300c, or 4300d may be fixedly connected to the input face 4111A of the monolithic body 4110 at a respective output end 4302a, 4302b, 4302c, or 4302d, thereby defining a respective engagement spot 4101a, 4101b, 4101c, or 4101d, which is defined as a volume, area, or point of (fixed) engagement between the output end of the optical fiber and the input face 4111A. Each optical fiber 4300a, 4300b, 4300c, or 4300d may be fixedly connected to the input face 4111A of the monolithic body 4110, for example, by splicing, welding, gluing, fusing, and / or via an optical connector or node.

[0057] According to some embodiments, the optical fibers 4300a, 4300b, 4300c, and 4300d may be connected to the output face 4111B of the monolithic body 4110, for example, by slicing, melting, welding, bonding, etc., and may be an integral part of the beam combining device 4100.

[0058] According to some embodiments, the monolithic body 4110 may be configured to direct an incident beam entering through the input face 4111A towards the output face 4111B so that the output beam reaches the phase mask 4112 at an equally specific output separation angle corresponding to the design of the phase mask, and optionally at a specific output angle relative to the major axis.

[0059] According to some embodiments, the phase mask 4112 may be engraved, etched or embossed into the output face 4111B of the monolithic body 4110 and may be designed for CBC.

[0060] For example, the phase mask 4112 may be designed as a phase mask, e.g., a diffraction grating mask, to combine the output beams passing through the phase mask 4112 into a single coherent output combined beam 4500 with scaled-up power and high output beam quality.

[0061] 5, a beam combining device 5000 is shown having a monolithic body 5200 with a collimator design and a separate external OE 5300 with an embedded phase mask, according to some embodiments. The beam combining device 5000 may also include multiple optical fibers, such as optical fibers 5100a, 5100b, 5100c, 5100d, and 5100e, fixedly connected at their output ends to a planarized input face 5210A of the monolithic body 5200.

[0062] Each of the optical fibers 5100a, 5100b, 5100c, and 5100d may be configured to guide light generated from one or more light sources and output the guided light from its output end that connects to the input face 5210A of the monolithic body 5200. The beams output from the output ends of the optical fibers 5100a, 5100b, 5100c, and 5100d may be configured to enter the monolithic body 5200 at equal spacing from its flattened or straight input face 5210A and at equal separation angles (hence referred to as "incident beams") that, in this configuration, are parallel to each other and therefore at an angle of zero with respect to the major axis 5210A.

[0063] The monolithic body 5200 may be completely transparent and may have an output surface 5210B located on the major axis x5 and curved to form a lens-like collimator design for collimating an incident beam incident at zero angle of incidence with respect to the major axis x5 to a focal point FP in a focal plane that is substantially perpendicular to the major axis x5 and a distance D away, where D is defined as the focal length. The OE 5300 may be located on that focal plane a focal distance D from a collimation peak P of the output surface 5210B of the monolithic body 5200, where D may be defined as the focal length. As seen in FIG. 5 , the flattened input surface 5210A may also be perpendicular to the major axis x5 to allow the incident beams to be incident parallel to each other and to the major axis x5.

[0064] The OE 5300 may include a phase mask 5301, for example etched, embossed, or adhered thereto, configured to combine the output beams exiting the output face 5210B of the monolithic body 5200 to output a combined output beam 5500, optionally directed along a major axis x5.

[0065] The OE 5300 may be a diffraction grating such as a beam splitter with an etched, embossed, or bonded phase mask corresponding to the incident and / or exiting beam characteristics such as wavelength, phase, intensity, etc., as well as the design, dimensions, and / or properties of the collimator monolithic body such as focusing characteristics, focal length, etc. The design of the phase mask may also depend on the separation angle θ (theta) of the optical beams exiting and / or entering the monolithic body 5200 from the output and / or input faces 5210B / 5210A.

[0066] Referring now to Figure 6, there is shown a beam combining device 6000 according to another embodiment having a number of optical fibers 6100a, 6100b, 6100c and 6100d (connectable to one or more light sources for outputting coherent incident beams) and a monolithic body 6200 with three surfaces.

[0067] The monolithic body 6200 may have three surfaces: a planarized input face 6210A that can be fixedly connected to optical fibers 6100a, 6100b, 6100c, and 6100d, a planarized output face 6210B in which a phase mask 6301 is embedded or connected via an OE 6300, and an additional third face 6210C positioned between the input face 6210A and the output face 6210B.

[0068] The third surface 6210C may be curved and reflective, for example by coating or attaching a reflective layer 6211 to its inside or outside, to direct incident beams entering the monolithic body 6200 parallel to the input surface 6210A towards the output surface 6210B by reflecting the incident beam so that the separation angle between each adjacent output beam matches the design and positioning of the phase mask 6301 of the OE 6300.

[0069] According to some embodiments, the phase mask 6301 of the OE 6300 may include a diffraction grating phase mask or any other mask profile design that allows the output beams to be combined into a coherent power-scaled combined output optical beam 6500.

[0070] The geometric shape of the monolithic body 6200 and the relative positioning of its input surface 6210A, third surface 6210C and output surface 6210B, as well as the curved shape of the third surface 6210C, may be such that an incident beam, such as beam 6101a or 6101d emitted from optical fibers 6100a and 6100d, respectively, entering from the input surface 6210A is converged / focused to a focal point located at the output surface 6210B, where the phase mask 6301 is also located.

[0071] According to some embodiments, the input surface 6210A may be flattened and define an axis x6 to which the flattened output surface 6210B may be perpendicular (i.e., the input surface 6210A may be perpendicular to the output surface 6210 and engage with it via an engagement axis perpendicular to the axis x6), where the curvature of the (reflective) third surface 6210C and the design and positioning of the phase mask 6301 may be such that the combined output optical beam 6500 is output parallel to the x6 axis direction.

[0072] Now, referring to Figure 7, there is shown a beam combining device 7000 having a number of optical fibers 7100a, 7100b, 7100c, and 7100d (which can be connected to one or more light sources to output coherent input beams) and a hemispherical or lens-shaped monolithic body 7200 having a curved input face 7210A and a flattened output face 7210B.

[0073] Output face 7210B of monolithic body 7200 may be integrally connected to OE 7300 or may have phase mask 7301 embedded thereon so that the output beams arrive at output face 7210B at a specific, equal output separation angle θ1 (theta 1) that should match the design of phase mask 7301. A specific value of equal output separation angle for all output beams can be achieved by connecting optical fibers 7100a, 7100b, 7100c, and 7100d to curved input face 7210A at equal intervals from one another, and optionally configuring curved input face 7210A to be spherically or hemispherically symmetric about major axis x7, so that the input separation angle θ1 (theta 1) between the input beams is the same for all input beams and / or all input beams are focused to a single focal point located on major axis x7. In this configuration, light output by optical fibers 7100a, 7100b, 7100c, and 7100d is directed at an angle toward planarized output face 7210B, focusing the incident beam to a single focal point located on output face 7210B that lies on major axis x7, which may be defined as the axis perpendicular to output face 7210B.

[0074] According to some embodiments, the phase mask 7301 may be designed and positioned to combine all of the output beams into a single combined output beam 7500 that may propagate along the major axis x7.

[0075] Another way in which an incident beam can be collimated or focused can be achieved by using a monolithic body with a varying refractive index, for example, using a monolithic body with graded indexing (GRIN), where the refractive index varies gradually, which can create the effect of focusing or steering the incident beam.

[0076] FIG. 8 shows a beam combining device 8000 including multiple optical fibers 8100 a , 8100 b , 8100 c , and 8100 d , a monolithic body 8200 having a graded refractive index configuration, and a separate phase mask 8300 .

[0077] According to some embodiments, the monolithic body 8200 may include a gradual refractive index change in the monolithic body 8200 that can create a lens-like focusing effect to focus an incident beam to a single focal point. For example, the monolithic body 8200 may have a cylindrical shape such that the refractive index gradually changes (i.e., gradually increases or decreases) toward a central plane that includes the central cylindrical axis x8 or axis x8, which may be the major axis, and the outer cylindrical region of the monolithic body 8200 may be designed to have a lower refractive index (shown in dark gray) than the inner region (shown in light gray to white).

[0078] The monolithic body 8200 may have a planarized input face 8210A that allows light from the optical fibers 8100a, 8100b, 8100c, and 8100d to enter parallel to each other and to the major axis x8, and an output face 8210B that is planarized and may be parallel to the input face 8210A, i.e., also perpendicular to the major axis x8, thereby allowing easier bonding of the optical fibers 8100a, 8100b, 8100c, and 8100d to the input face 8210A and attachment, etching, or embossing of a phase mask 8300 onto the output face 8210B of the monolithic body 8200.

[0079] According to some embodiments, as shown in FIG. 8, the phase mask 8300 may be implemented as a diffraction grating mask etched or embossed onto the output face 8210B when the focal point is located on the output face 8210B.

[0080] Alternatively, the phase mask 8300 may be implemented as a separate diffractive optical element (DOE) attached to the output face 8210B if the focal point of the incident beam is on the output face 8210B, or located externally therefrom if the focal point is located outside the monolithic body 8200.

[0081] The phase mask 8300 can be positioned parallel to the input and output faces 8210A and 8210B and (thus) perpendicular to the major axis x8, ultimately allowing the output beams to be focused onto the plane on which the phase mask 8300 is positioned at an equal, specific separation angle θ8 (theta 8) corresponding to the mask profile design, and the output beams to be combined into a single coherent combined output beam 8500, optionally propagating along the major axis x8.

[0082] The monolithic body gradually indexed configuration depicted in Figure 8 illustrates an embodiment in which beams passing through the monolithic body are focused to a focal point or region due to the index change, located on a phase mask of the OE that is external to the monolithic body. Other configurations may be such that the curvature of beams passing through the monolithic body causes them to be focused to a focal point or region located on a phase mask that may be synthesized or positioned at the output face of the monolithic body.

[0083] Embodiments or components of embodiments of the systems and methods described herein, e.g., monolithic body 1110, 4110, 5200, 6200, 7200, 8200, and / or OE 1120, 5300, 7300, and / or phase mask 1121, 4112, 5301, 6301, 7301, 8300, may be shown in the drawings in a two-dimensional (2D) configuration for illustrative purposes only, with reference to components that may be 3D.

[0084] The embodiments provided herein may also include systems that use multiple coherent beam combining devices (also referred to herein as CBC devices) in a network configuration that provides enhanced power scaling through the use of additional optical signal amplification, for example, by using one or more additional CBC devices and / or spectral beam combining (SBC) devices.

[0085] For example, such a system may include a first set of CBC devices, each using multiple optical waveguides, such as optical fibers, fixedly connected to its respective input face, each outputting an amplified coherent combined output optical beam. The combined output optical beam of each CBC device may then be guided / directed as an incident optical beam through its respective input face toward another beam-combining device, such as a CBC or SBC device, where the additional beam-combining device may be configured to cause further amplification of all the coherent combined beams from several other beam-combining devices. The steering or direction of the coherent combined output optical beam may be accomplished using optical waveguides connecting to the output face of each CBC device, or by positioning the additional beam-combining device so that the optical beam reaches its input face through air (unguided).

[0086] The configuration may be repeated by using the output beam of multiple CBC devices as the input beam of one or more other CBC devices with the same or different configurations, such as to form any kind of CBC device network (herein a "netted CBC system"), depending on the material property limitations of the CBC device (e.g., maintaining rigidity at high temperatures caused by the high power beams directed thereby) and any losses that may arise.

[0087] 9 shows a CBC system 9000 based on a mesh of multiple beam combining devices, according to some embodiments. The CBC system 9000 includes multiple input CBC devices, such as input CBC devices 9100A, 9100B, and 9100C, and an additional CBC device 9400. According to some embodiments, each of the input CBC devices 9100A, 9100B, and 9100C has multiple input optical fiber sets, such as fiber sets 9110a, 9110b, and 9110c, respectively, and / or is fixedly connected to output a coherent combined output beam that can be guided via respective optical waveguides 9120a, 9120b, and 9120c toward the input face of the additional CBC device 9400.

[0088] Each of the CBC devices 9100A, 9100B, and 9100C may include a monolithic body and a phase mask according to one of the configurations described above. The monolithic body of each of the CBC devices 9100A, 9100B, and 9100C may be configured to focus an incident beam emitted from the optical fiber of the respective CBC device to a focal point located on a focal plane where the phase mask is located. The phase mask may be located on the output surface of the respective monolithic body (e.g., in this case, the phase mask may be etched, embossed, or attached / synthesized to the output surface and flattened), or may be located outside the monolithic body (in this case, the phase mask may be implemented on a separate OE, such as a DOE).

[0089] The CBC devices 9100A, 9100B, and 9100C may be similar, identical, or different in configuration to one another, for example, in the type, chemical composition, wavelength and / or number, size, geometry, number and / or configuration of the optical fibers connected to them, depending on the system requirements.

[0090] Each of the optical waveguides 9120a, 9120b, and 9120c may be designed and positioned relative to the output face of the monolithic body of its respective CBC device such that it can direct the combined output beam in a coherent, collimated manner to maintain high output power and avoid power and / or coherency losses. An additional CBC device 9400 may be configured to focus and combine the incident beams emanating from the waveguides 9120a, 9120b, and 9120c by configuring the monolithic body to focus the incident beams to a focal point located on a focal plane and outputting a coherent final output beam 9500 that can be significantly additively amplified using a phase mask (not shown) located on the focal plane to cause CBC of the incident beams.

[0091] Embodiments of the meshed CBC system can be designed in any branching / network configuration, for example, using multiple additional CBC devices whose output beams serve as input beams to still additional CBC devices.

[0092] The phase mask in one or more of the above embodiments may be configured as a diffraction grating mask, such as a beam splitter, used in the reverse manner for beam combining. The diffraction grating mask may be implemented as an etching or embossing on a surface (e.g., the output face of a monolithic body of a beam combining device or the surface of a separate element). According to some embodiments, the diffraction grating phase mask may be implemented as an immersion diffraction grating mask (e.g., by immersing the grating in a material with a higher refractive index) to flatten the outside of the phase mask and / or improve the quality of the output beam. A flat, planar output face of the phase mask may be required, for example, to enable its waveguide to be fixedly attached to the flat output face of the phase mask of the CBC device, for use in a CBC device of a reticulated CBC system.

[0093] According to some embodiments, the phase mask may be made from a transparent or at least partially transparent material.

[0094] Spectral beam combining (SBC) can be used to power scale fiber lasers to very high output powers (e.g., output powers of 2000 watts or more) by combining laser beams of different wavelengths, requiring moderate bandwidth and wavelength control of the individual sources.

[0095] The general principle of SBC is to combine several incident beams of non-overlapping optical spectrum using some kind of wavelength-sensitive beam combiner, such as a prism or optical grating element, which can deflect the incident beams according to their wavelength.

[0096] Combining multiple beams with non-overlapping spectra is done by directing all the beams onto a phase mask, such as an optical grating, with each beam directed at a slightly different angle to the phase mask so that all beams exit the mask at the same angle.

[0097] Assuming each beam is monochromatic, its ideal relative angle with respect to the optical grating plane (ideal beam combining) can be related to its respective wavelength according to the following mathematical relationship: θ i ∝gλ i (1)

[0098] G represents the density of the lattice, and λ i represents the wavelength of each incident beam.

[0099] 10A (Background Art) is a schematic diagram of an SBC optical setup 80 based on a single diffraction scheme. The SBC optical setup 80 includes a linear array of lasers outputting collimated optical beams 81, a focusing lens 82, and a diffraction grating optical element 83.

[0100] 10A, parallel incident optical beams 81 are directed to a focusing lens 82, which focuses the beams and directs them to a diffraction grating optical element 83, which diffracts the beams to a common output angle and multiplexes the beams into a single combined output optical beam 85. In this configuration, each beam is at a different wavelength, and the focusing of incident optical beams 81 causes each optical beam to impinge on diffraction grating optical element 83 at a different angle, allowing diffraction grating optical element 83 to deflect each beam in the same output direction (along axis y). Because all elements of optical setup 80 are spaced apart from one another, maintaining alignment and stability can be difficult, especially over long periods of time.

[0101] In practice, the ability to combine many optical beams covering a wide wavelength band and maintain high beam quality is also limited when using an optical setup 80 such as that shown in Figure 10A. The need to impinge the grating optical elements 83 at different angles, i.e., at a different angle for each laser wavelength, allows the use of a common focusing lens 82 only for a particular equidistant wavelength spacing between adjacent optical beams. This means that if the wavelength spacing Δλ between channels is small, then a small angular spacing Δθ is required, and for finite fiber pitches, the focal length of the lens may be prohibitive for certain applications.

[0102] In addition, a finite spectral bandwidth δλ is required to avoid nonlinear phenomena in high-power fiber lasers, so the use of the grating optical element 83 can degrade the quality of the output optical beam according to the following relationship: δθ∝gδλ (2)

[0103] where δθ is the angular spread of the diffracted beam, g is the grating density of the lines, and δλ is the wavelength spread of the respective laser optical beam.

[0104] According to equation (2), the divergence of a beam with a finite spectral width δλ is degraded (divergence angle spread) by a factor proportional to its spectral width δλ, where this factor is determined by the optical properties of each diffraction grating optical element 83.

[0105] The use of a narrowband laser beam (typically less than 10 GHz) with a single diffraction grating, when used in fiber laser amplification, primarily limits the maximum power of the laser beam due to stimulated Brillouin scattering (SBS), which is characterized by strong reflections back into the laser. The power threshold of the SBS setup 80 is proportional to the fiber length (L) and bandwidth (ΔV) and inversely proportional to the core diameter (A).

number

[0106] Increasing the core diameter reduces the beam quality (higher optical modes are more easily excited in fibers with larger core diameters), and increasing the bandwidth impairs the divergence of the combined beam; these two parameters limit the total power and quality of the output optical beam.

[0107] High-power fiber lasers that require many channels are 2 It should be noted that the magnitude of θ can limit the quality of the beam.

[0108] Also, to achieve efficient SBC, the alignment of the beam positions and the angles at which each of the optical gratings impinges must be very precise and must remain so throughout the entire procedure.

[0109] FIG. 10B (Background Art) is a schematic diagram of an SBC optical setup 90, which has two identical diffraction grating elements (DGEs): a first DGE 93A and a second DGE 93B, multiple light sources 91a, 91b, 91c, and 91d that output multiple parallel incident optical beams each having slightly different wavelengths, and multiple focusing lenses (one for each light source), such as lenses 92a and 92b.

[0110] As shown in FIG. 10B, lenses 92a and 92b are positioned so that the output points of their respective light sources are at the focal points of the respective lenses, directing their respective optical beams of substantially equal diameter (with low beam divergence) toward a first DGE 93A. Due to their different wavelengths, the beams impinge on the first DGE 93A on trajectories parallel to each other and to axis y2 and are deflected from the first DGE 93A on trajectories non-parallel to each other and to axis y2. The optical beams deflected from the first DGE 93A are directed toward and impinged upon a second DGE 93B, which combines them by deflecting them in the same direction parallel to each other and to axis y2, to output a combined multispectral output optical beam 95. In this configuration, the two DGEs 93A and 93B must be positioned angularly parallel to each other with respect to the trajectories and y2 of the incident beams.

[0111] Aspects of the disclosed embodiments relate to beam combining devices each having a monolithic body configured for SBC of multiple spectrally differentiated optical beams emanating from multiple light sources, such as from the output ends of multiple optical fibers, either fixedly connected or connectable, the beam combining devices being configured for SBC of the optical beams. The monolithic bodies may include at least an input surface, a diffractive surface, and an output surface.

[0112] According to some embodiments, the monolithic body may be configured to direct incident optical beams incident through the input surface of the monolithic body through multiple diffractive optical paths within the monolithic body, for example, by directing the incident optical beams to impinge on a diffractive surface at least twice to combine the incident optical beams into a single combined multi-spectral combined output optical beam and exit the monolithic body through the output surface. The multiple diffractive paths along which the incident optical beam is directed may be enabled using a single diffractive surface, by causing the incident optical beam to be internally reflected by the monolithic body, for example, by using one or more reflective surfaces of the monolithic body, or by configuring at least a portion of the monolithic body for total internal reflection (TIR) ​​or partial internal reflection (PIR).

[0113] According to some embodiments, the configuration of the monolithic body, e.g., its geometric shape, dimensions, elements, and / or material(s), can be designed according to the respective characteristics and / or positioning of the incident optical beams, such as where each optical fiber is connected on the input face (defining the point of incidence and its trajectory for that particular incident beam), the wavelength or wavelength band of the particular incident optical beam, etc. The input face, output face, and / or diffractive face of the monolithic body can be planar (flat) to allow for easy connection of the fiber ends to the input face (e.g., by bonding, welding, etc.) and to allow for multiple diffractive optical paths of the incident optical beam within the monolithic body. Other embodiments can include a curved configuration of one or more of these surfaces.

[0114] According to some embodiments, the diffractive surface may include one or more phase masks configured to diffract each impinging beam, for example, by deflecting it according to its respective wavelength. Non-limiting examples of such phase masks may include grating masks, prisms, etc. The phase mask(s) may be etched, embossed, or attached to the diffractive surface. The phase mask(s) may be embedded in a separate optical element attached to one side of a monolithic body, thereby forming that monolithic surface.

[0115] According to some embodiments, each incident optical beam can enter the monolithic body through its input surface at the same incident angle, i.e., parallel to each other, and can be directed inside the monolithic body toward the phase mask to be deflected through a first deflection. The deflected optical beams, because they are incident parallel to each other and have different wavelengths, have different trajectories. The monolithic body can be configured to redirect the optical beams initially deflected from the diffractive phase mask toward the same phase mask (e.g., by deflecting them again using reflective and / or refractive means embedded within the monolithic body), where the reflected optical beams return and impinge on the phase mask (again) in trajectory directions different from each other, so that the returning optical beams (now with different trajectory directions) are combined into a single output optical beam. The phase mask can deflect each optical beam at an angle different from the angle at which they impinged. After the beams are diffracted a second time, all optical beams exit the monolithic body (e.g., via the output surface) at the same trajectory angle (i.e., the same propagation direction) to form a combined output optical beam.

[0116] According to some embodiments, the monolithic body may be made at least in large part from a transparent material such as glass, fiberglass, or the like, and may have a uniform single index of refraction or a varying index of refraction.

[0117] According to some embodiments, a beam combining device may be defined as including a monolithic body and an optical fiber fixedly connected thereto.

[0118] 11 is a schematic diagram of an SBC device 400 according to some embodiments. The SBC device 400 may include multiple optical fibers 410a, 410b, 410c, 410d, 410e, and 410f and a monolithic body 420. The monolithic body 420 may be a single monolithic 3D element or object including a planar input face 421 fixedly connected to the output ends of the multiple optical fibers 410a-410f, a planar diffractive surface 422 having a phase mask 422a, such as a diffraction grating mask, etched or embossed thereon or attached / combined thereto, a reflective surface 423 that is at least partially reflective, and an output face 424 from which a combined output optical beam 450 emerges.

[0119] According to some embodiments, the monolithic body 420 may be made at least in large part from a transparent material such as glass, fiberglass, or the like, and may optionally have a uniform single index of refraction.

[0120] According to some embodiments, each side of the monolithic body 420 may be coated with a reflective material 423 a or attached to a reflective element to form a reflective surface 423 of the monolithic body 420 .

[0121] According to some embodiments, as shown in FIG. 11 , the input surface 421 may be a planar, flat surface to which the optical fibers 410a-410f may be fixedly connected, for example, by welding, bonding, and / or gluing, to their output ends (which output the incident optical beams). The connection of the optical fibers 410a-410f to the input surface 421 may be such that the incident optical beams enter the monolithic body parallel to one another and define a major axis y4 (parallel thereto). Optionally, the engagement points of the connections between the input surface 421 and the output ends of the optical fibers 410a-410f may be symmetrically arranged and / or equally spaced. The input surface 421 may be polished to increase the contact (engagement) area with the output ends of the optical fibers 410a-410f.

[0122] According to some embodiments, the diffractive surface 422 and the reflective surface 423 are both planar and substantially parallel to one another, such that each of the incident optical beams output by the optical fibers 410a-410f double impinges on the diffractive surface 422 by directing the incident beam (incident on a parallel trajectory) from the input surface 421 to the diffractive surface 422, enabling a double diffraction scheme in which the beam impinges and is deflected in different angular directions from the diffractive surface 422 to the reflective surface 423, from the reflective surface 423 to the diffractive surface 422 (again), and from the diffractive surface 422 to the output surface 424. In the final optical path of the optical beam from the diffractive surface 422 to the output surface 424, all of the optical beams are parallel to one another to form a combined output optical beam 450 upon exiting the monolithic body 420.

[0123] To better illustrate the double-diffraction optical path traversed by each beam due to the configuration of the monolithic body and for its particular wavelength, one can follow the marked optical path of the incident optical beam 41 a of the optical fiber 410 f (see FIG. 11 ): the optical beam 41 a enters the monolithic body 420 through its input face 421 at a first angle parallel to the y4 axis, then impinges on the phase mask 422 a of the diffractive face 422, whereby it is deflected in the direction of a different trajectory 41 b at a non-zero angle relative to the axis y4 and directed to impinge on the reflective face 423. The impinging beam on trajectory 41 b is reflected by the reflective face 423 back towards the diffractive face 422 along another trajectory 41 c angled relative to the axis y4, where it is again deflected by the diffractive face 422 and directed along another trajectory 41 d towards the output face 424.

[0124] As shown in FIG. 11, all optical beams emitted from optical fibers 410a-410f enter monolithic body 420 parallel to each other, so their initial trajectories are parallel and directed toward diffracting surface 422. However, due to the different wavelengths of the optical beams, the angles of the second trajectories of the beams directed toward reflective surface 423 are different for each beam (because the diffraction angle depends on the wavelength of the impinging beam). Therefore, the optical beams are also reflected back to diffracting surface 422 at different trajectory angles, and each optical beam reaches phase mask 422a again at different trajectory angles. In this way, phase mask 422a can combine the optical beams by deflecting them all again by the same trajectory angle about axis y4. In the second diffraction, the optical beams are diffracted at the trajectory angle required to combine them into a single output optical beam.

[0125] According to some embodiments, the diffractive surface 422 and the reflective surface 423 are parallel to each other and tilted relative to the input surface 421 .

[0126] As shown in FIG. 11, the monolithic body 420 may have additional surfaces that may be flat or curved such that the input, diffractive, reflective, and output surfaces have a 3D configuration, for example, forming a 3D body in which the diffractive surface 422 is parallel and opposite to the reflective surface 423 and at an angle to the input surface 421.

[0127] According to some embodiments, the incident beams output by the optical fibers 410a-410f originate from multiple light sources (not shown), such as multiple input laser devices or LED light sources, each configured to output light of a different wavelength.

[0128] According to some embodiments, one or more external optical elements may be used to prevent or reduce divergence of the output optical beam 450 emitted from the monolithic body 420, such as a focusing lens 470, positioned near the output face, for example.

[0129] The relationship between beam quality and double diffraction design parameters can be expressed as follows:

number

[0130] where BQ is the beam quality of the output combined optical beam, Δx is the lateral separation between the fiber laser sources, δλ is the spectral bandwidth of a typical source, Δλ is the wavelength separation of the sources, and ω is the beam waist (output beam radius).

[0131] As can be seen in equation (4), the expected beam quality is proportional to the lateral separation distance Δx between the incident points of the incident optical beams and inversely proportional to the beam waist ω 0 .

[0132] Unlike conventional setups where Δx and ω are on the order of a few millimeters, in SBC devices disclosed herein, such as SBC device 400, the spacing between the incidence points of the incident optical beams may be on the order of hundreds of microns, but the beam waist ω may be very large such that the corresponding beam waste ω may be in the range of 0.5 to 2 millimeters (only Δx may be on the order of 2 to 5 millimeters).

[0133] If it becomes possible to significantly reduce the spacing between the incident optical beam points, then BQ (or M 2 )=1(M 2 = 1 is the best beam quality (M 2 ) can be achieved, which can significantly improve the quality of the output optical beam. Therefore, the beam quality increases as the lateral distance Δx decreases.

[0134] According to other embodiments, the incident optical beam can be directed in free space such that it can enter the monolithic body 420 (without via an optical fiber bonded to the input face 421). According to some embodiments, fixedly connecting (e.g., bonding) the optical fibers 410a-410f to the monolithic body 420, for example, via welding directly to the (e.g., glass) input face 421, can eliminate the need for end caps (ECs) to seal the tips of the optical fibers, since light propagation occurs within the glass. In this way, drawbacks associated with end caps, such as back reflection, where light reflects from the tip of the end cap back into the optical fiber, resulting in power loss, are eliminated. Thus, the solution provided herein can dramatically reduce loss and increase output power.

[0135] Attaching (e.g., splicing) the optical fibers directly to the input face eliminates the need to use end caps to seal the ends of the fibers, thereby allowing for reduced spacing between the optical fibers, making the overall SBC device configuration very compact.

[0136] It is highly desirable to space the fibers closely together because beam quality increases as the fiber tip separation decreases. Note that the beam quality of a given grating-based SBC scheme is determined by the fiber tip spacing: the smaller the fiber tip separation, the better the beam quality. This can be understood by examining equation (5), which relates the focal length of the lens used to different wavelengths. FL = Δx / gΔλ(5)

[0137] Δx is the separation between the fiber tips and FL is the focal length.

[0138] Because the relative beam divergence is proportional to FL: δθ / θ ∝ FL × gδλ, the effect of the laser bandwidth δλ becomes less significant as the focal length FL decreases. Therefore, attaching the fiber directly to the bulk glass surface eliminates the need for high-precision bulk-spliced ​​fiber laser arrays (with an expected doubling of sensitivity).

[0139] The monolithic design of the SBC devices provided herein, using a single 3D monolithic body that is integrally or non-integrally connected to a phase mask on a reflective surface and fixedly connected to an optical fiber, can dramatically reduce the sensitivity of alignment to physical and mechanical influences such as shock, vibration, shaking, and thermal changes.

[0140] According to some embodiments, the SBC devices discussed herein may be encased or held by a designated, specially designed casing or holder.

[0141] According to some embodiments, the SBC devices disclosed herein may be further advantageous because they have the following characteristics:

[0142] Multiple (e.g., dual) optical path schemes allow the use of spectral bandwidths in the nanometer range (as opposed to single diffraction schemes that limit spectral bandwidths to the picometer range), which allows the use of a variety of light sources and optical fibers without complex bandwidth control schemes.

[0143] The multiple optical path scheme and fixed connection of optical fibers to a monolithic body results in a robust, compact and accurate SBC for a broadband wavelength spectrum ranging from 1030 to 1080 nm or 1900 to 2100 nm without the need for a bandwidth control scheme.

[0144] Because the optical fibers are fixedly connected to the monolithic body, the possibility of misalignment is greatly reduced (optionally by several orders of magnitude): there are essentially no moving elements that can lose their alignment during vibration and / or environmental changes over time.

[0145] The combined output optical beam exiting the monolithic body may have a relatively large beam diameter (in some configurations), which allows for power scaling up of the original incident optical beam (e.g., for fiber laser requirements). For example, the combined output optical beam exiting the monolithic body may be characterized by a spot size that is approximately 3-4 times larger than the spot size of the incident optical beam.

[0146] Because thermal degradation and optical damage are related to beam intensity, which in turn is inversely proportional to beam area, fiber lasers using the SBC technology described herein can be upgraded to higher laser powers, e.g., 10-15 times the power used to impinge on a grating facet by a single beam.

[0147] Most of the risk of optical damage comes from changes in the medium the beam travels through at high power densities. In the monolithic spectral beam combining scheme described herein, the optical beam is maintained in the bulk of the monolithic body throughout the combining process, leaving the monolithic body at a much larger diameter, thereby reducing the threat of optical damage by orders of magnitude.

[0148] 12 illustrates an SBC device 500 in accordance with some embodiments, in which the reflective and diffractive surfaces are not positioned parallel to one another (i.e., are angled relative to one another). The SBC device 500 includes multiple optical fibers, such as optical fibers 510a, 510b, 510c, and 510d, and a monolithic body 520. The monolithic body 520 includes an input surface 521, a diffractive surface 522 having one or more phase masks, such as one or more diffraction grating masks, a reflective surface 523, and an output surface 524. The monolithic body 520 may include other surfaces to form desired angular positioning and / or other geometric relationships between the input surface, output surface, diffractive surface, and reflective surfaces 521-524 relative to one another.

[0149] According to some embodiments, a focusing lens 525 may be used when the outgoing combined output optical beam 550 exits the monolithic body 520 in a divergent manner to collimate the combined output optical beam 550. The lens 525 may be positioned outside the output face 524.

[0150] According to some embodiments, the incident optical beams enter the monolithic body 520 through the input face 521 parallel to each other and to the axis y5, although other surfaces may be angled relative to the axis y5 to allow multiple optical paths for each incident optical beam within the monolithic body. The fixed connections between the monolithic body 520 and the optical fibers 510a-510d are such as to allow the incident optical beams to enter the monolithic body 520 on parallel incident trajectories.

[0151] As shown in FIG. 12, the reflective surface 523 in these embodiments is angled relative to the diffractive surface 522 and the input and output surfaces 521 and 524 .

[0152] FIG. 13 illustrates an SBC device 600 with a multiple internal reflection scheme according to some embodiments. The SBC device 600 includes multiple optical fibers, such as optical fibers 610a, 610b, 610c, and 610d, and a monolithic body 620. The monolithic body 620 may include an input surface 621, a diffractive surface 622 having one or more phase masks, such as one or more grating phase masks 622a, a reflective surface 623, and a partially reflective output surface 624. The monolithic body 620 may include other surfaces to form desired angular positioning and / or other geometric relationships between the input surface, output surface, diffractive surface, and reflective surfaces 621-624 relative to one another.

[0153] According to these embodiments, the output face 624 includes a transparent region 624a through which the combined output optical beam 650 can exit the monolithic body 620, and a reflective region 624b surrounding the transparent region 624a, such that an optical beam within the monolithic body 620 that strikes the opaque surrounding reflective region 624b is directed internally back towards the diffractive surface 622 until it reaches the correct trajectory angle and exits the output face 624 through that transparent region 624a.

[0154] In these configurations, an optical beam entering from input surface 621 may be reflected several times by reflective surface 623 and / or the reflective surfaces of reflective region 624b depending on its incident trajectory angle, its respective wavelength, and the angular positioning of surfaces 521-524 relative to one another.

[0155] The reflective surface 623 and / or the reflective region 624b of the output surface 624 can be achieved either by coating these surfaces / regions with a reflective coating material or by attaching a reflective element(s) to the transparent surface of the monolithic body 620 beyond its respective side.

[0156] The phase mask(s) 622a of the monolithic body 620 may be etched, embossed, or attached to the side of the monolithic body that forms its diffractive surface 622, and may be configured, for example, as a diffraction grating mask.

[0157] According to some embodiments, the incident optical beams enter the monolithic body 620 through the input face 621 parallel to each other and to the axis y6, although other surfaces may be angled relative to the axis y6 to allow multiple optical paths for each incident optical beam within the monolithic body. The fixed connections between the monolithic body 620 and the optical fibers 610a-610d are such as to allow the incident optical beams to enter the monolithic body 620 on parallel incident trajectories.

[0158] According to some embodiments, the SBC device 600 may include one or more focusing lenses, such as focusing lens 670, for collimating the combined output optical beam 650.

[0159] According to other embodiments, the SBC device may include additional reflective surfaces in addition to or instead of the reflective surface and / or output surface to enable total internal reflection (TIR) ​​of the beam until it is at the correct trajectory angle to exit the monolithic body.

[0160] Aspects of the disclosed embodiments relate to systems that integrate coherent and spectral beam combining devices and techniques. For example, the system may include multiple CBC devices, each combining multiple coherent and monospectral optical beams into a combined coherent monospectral output optical beam, where each CBC device is designed to output combined optical beams at different wavelengths or narrow wavelength bands relative to one another, and one or more SBC devices, each configured to perform spectral beam combining of the optical beams output by the multiple CBC devices. Referring to FIG. 14, a system 700 for SBC of multiple spectrally differentiated optical beams emanating from multiple CBC devices is shown, according to some embodiments.

[0161] System 700 includes an SBC device 720 configured for spectrally combining spectrally differentiated incident optical beams, and multiple CBC devices, such as CBC devices 710A, 710B, and 710C, each configured to perform CBC on multiple coherent incident optical beams and output combined coherent optical beams, such as combined coherent optical beams 715a, 715b, and 715c, of different wavelengths relative to each other. SBC device 720 is positioned and configured to spectrally combine all output optical beams from multiple CBC devices 710A-710C, for example, to enable optical power scaling of incident optical beams that have already undergone prior coherent power scaling, and to output a final spectrally combined output optical beam 750.

[0162] For example, as shown in FIG. 14, the CBC device 710A may be configured to combine and output a coherent combined optical beam of a first wavelength λ1, the CBC device 710A may be configured to combine and output a coherent combined optical beam of a second wavelength λ2, and the CBC device 710A may be configured to combine and output a coherent combined optical beam of a third wavelength λ3, where λ1 ≠ λ2 ≠ λ3.

[0163] According to some embodiments, for each CBC device 710A / 710B / 710C, the coherent incident optical beam incident thereon may originate from multiple sets of optical fibers, such as fiber sets 711a, 711b, and 711c, each fiber set outputting an optical beam of a different wavelength and fixedly connected to the respective CBC device 710a, 710b, and 710c.

[0164] According to some embodiments, CBC devices 710a, 710b, and 710c may be configured according to one or more of the CBC devices discussed above, each having a phase mask and geometry corresponding to the respective wavelength or wavelength band of the incident optical beam.

[0165] According to some embodiments, the SBC device 720 may be configured according to any one of the SBC device configurations discussed above, using a configuration that allows for a dual optical path to impinge on its diffractive surface at least twice, and according to the particular wavelengths of the optical beams output by the CBC devices 710a, 710b, and 710c.

[0166] According to some embodiments, the composite coherent optical beams 715a-715c output by the CBC devices 710A-710C, respectively, may be directed towards the SBC device 720 via optical waveguides, such as optical fibers, each configured to direct an optical beam of the respective wavelength and / or intensity of the respective CBC device.

[0167] An aspect of the disclosed embodiment relates to a method for coherent beam combining by using any type of CBC device, such as any of the beam combining devices described above, having a monolithic body and a phase mask, where the monolithic body is configured to focus incident optical beams to a focal point on which the phase mask is located, and the phase mask is located on a focal plane that includes the focal point and is configured to combine the impinging optical beams.

[0168] 15 shows a flowchart illustrating a CBC process for coherent beam combining using a CBC device having such a monolithic body and a phase mask. In some embodiments, the CBC process may include the following steps:

[0169] Providing a CBC device having a monolithic body and a phase mask (block 801), the monolithic body may include at least an input face and an output face, the phase mask may be positioned and configured to coherently combine optical beams directed through the monolithic body; In some embodiments, the method may further include directing multiple coherent optical beams onto the monolithic body at specific angles of incidence relative to the major axis (e.g., by using multiple light sources and optical fibers fixedly connected to the input face of the monolithic body, as described above with respect to the beam combining device embodiments) (block 802); In some embodiments, the method may additionally include directing an incident optical beam within the monolithic body such that the incident optical beam converges to a focal point defining a focal plane, and the phase mask may be positioned on that focal plane (Block 803); In some embodiments, the method further includes combining the optical beams that impinge on a phase mask of the CBC device (Block 804); and In some embodiments, the method may also include outputting a single coherent combined output optical beam and directing it outwardly from the CBC device (block 805).

[0170] Aspects of the disclosed embodiments relate to methods for spectral beam combining of multiple spectrally differentiated optical beams, for example, by using any one of the SBC device configurations described above.

[0171] FIG. 16 shows a flowchart illustrating an SBC process, according to some embodiments, which may include the following steps:

[0172] providing an SBC device having a monolithic body, the monolithic body having at least an input surface, an output surface, a diffractive surface, and optionally a reflective surface, the SBC device being configured for SBC via multiple diffractive optical paths, for example, by directing a spectrally differentiated incident optical beam incident through the input surface so as to impinge on the diffractive surface at least twice (block 811); In some embodiments, the method may further include directing the multiple spectrally differentiated optical beams to the monolithic body, e.g., via an input face of the monolithic body (block 812); In some embodiments, the method further includes combining incident optical beams by directing them through multiple diffractive optical paths into the monolithic body (Block 813); and In some embodiments, the method may also include outputting the single multispectral combined output optical beam and directing it externally from the SBC device (block 814).

[0173] Aspects of the disclosed embodiments relate to a cascaded beam combining method for beam combining of multiple optical beams emanating from a set of CBC devices by using at least one additional beam combining CBC or SBC device depending on the spectral output of the set of CBC devices.

[0174] Examples of such cascaded implementations are shown (but not limited to) in Figures 9 and 14 above.

[0175] Additionally, with reference to FIG. 17 , a cascaded beam combining method, according to some embodiments, includes providing a first set of CBC devices, each configured to combine multiple incident coherent optical beams and output a coherent combined output optical beam of a particular wavelength or wavelength band, where the combined output optical beams of the CBC devices may be spectrally differentiated, spectrally overlapping, or of the same wavelength or wavelength band (block 821).

[0176] In some embodiments, the method further includes providing at least one additional combining device each configured to combine output optical beams emitted from the set of CBC devices; in embodiments where the CBC devices are configured to output combined output optical beams of overlapping or identical wavelengths, the at least one additional combining device may be a CBC device configured to combine coherent optical beams of respective wavelengths or wavelength bands; and in embodiments where the CBC devices are configured to output spectrally differentiated combined output beams, the at least one additional combining device may be an SBC device configured to combine spectrally differentiated optical beams (block 822).

[0177] In some embodiments, the method includes directing output optical beams emitted from the first set of CBC devices toward an input face of at least one additional combining device (block 823); In some embodiments, the method further comprises combining the optical beams incident on at least one additional combining device (Block 824); and In some embodiments, the method outputs a single combined final optical beam and directs it outwardly from at least one additional combining device (Block 825).

[0178] The cascaded beam combining method can use any kind of network configuration, where multiple optical beams emanating from multiple beam combining devices can be combined several times in a cascaded manner via multiple additional combining devices.

[0179] A first set of CBC devices can be fixedly connected to multiple optical fibers to direct multiple coherent optical beams therein for CBC.

[0180] According to some embodiments, directing the optical beams output by the first set of CBC devices to the at least one additional combining device may be performed by air or via an optical waveguide.

[0181] Additional examples: Example 1 provides a beam combining device for coherently combining multiple spectrally coherent optical beams emitted from multiple optical fibers, the beam combining device comprising: a monolithic body that is at least partially transparent and has at least an input surface and an output surface, the input surface configured to be fixedly connected to the multiple optical fibers and to direct the multiple coherent input beams incident from the multiple optical fibers through the monolithic body; and a phase mask configured to combine output beams output from the output surface of the monolithic body to form a single combined output beam output therefrom.

[0182] In Example 2, the subject matter of Example 1 may include that the monolithic body is configured to focus all incident beams to a single focal point, and the phase mask is positioned on a focal plane that includes the focal point.

[0183] In Example 3, the subject matter of Example 2 may include the monolithic body being configured such that incident beams directed therethrough converge to a focal point at the same exit separation angle as each other, such that the separation angle and the focal point define a focal plane on which the phase mask is positioned.

[0184] In Example 4, the subject matter of Examples 1-3 may include that the input surface of the monolithic body is configured such that the multiple optical fibers fixedly connected thereto are arranged at equal intervals and equal incident separation angles from one another.

[0185] In Example 5, the subject matter of Examples 1-4 may include that a phase mask is etched or embossed into the output face of the monolithic body.

[0186] In Example 6, the subject matter of Examples 1-4 may include a phase mask attached to an output face of the monolithic body.

[0187] In Example 7, the subject matter of Examples 1-4 may include that the phase mask is embedded in a separate optical element (OE).

[0188] In Example 8, the subject matter of Example 7 may include the OE being located separately from the output face of the monolithic body.

[0189] In Example 9, the subject matter of Example 7 may include the OE being integrated into the output face of the monolithic body.

[0190] In Example 10, the subject matter of Examples 1-9 may include the phase mask being further designed according to at least one of the following characteristics of each of the incident and / or exiting optical beams: beam wavelength, beam wavelength band, beam phase, beam wavefront, beam waste, and beam radius.

[0191] In Example 11, the subject matter of Examples 1-10 can include, wherein the phase mask comprises a diffraction grating mask.

[0192] In Example 12, the subject matter of Example 11 can include the phase mask comprising a beam splitter.

[0193] In Example 13, the subject matter of Examples 1-12 can include the input face of the monolithic body being curved such that the relative angle of incidence between each pair of adjacent optical fibers is greater than zero to direct the beam toward a focal point or focal region at the output face of the monolithic body.

[0194] In Example 14, the subject matter of Examples 1-4 can include an input face of the monolithic body being planarized such that incident optical beams emanating from the optical fibers enter the monolithic body parallel to one another.

[0195] In Example 15, the subject matter of Examples 1-13 can include, wherein the monolithic body includes at least one additional surface having a reflective interior that directs the beam from the input surface toward the output surface of the monolithic body by reflecting the beam toward the output surface.

[0196] In Example 16, the subject matter of Example 15 can include wherein the reflective interior is formed by coating the interior of at least one additional surface with a reflective material.

[0197] In Example 17, the subject matter of Example 15 can include wherein the reflective interior is formed by attaching a reflective element to the interior of the at least one additional surface.

[0198] In Example 18, the subject matter of Examples 15-17 can include additional surfaces that are curved.

[0199] In Example 19, the subject matter of Examples 1-18 can include all of the optical fibers being designed to output optical beams at the same wavelength and / or wavelength band, such that all incident beams entering the monolithic body have the same wavelength and / or wavelength band.

[0200] In Example 20, the subject matter of Examples 1-19 can include, wherein each of the optical fibers is a double-clad optical fiber.

[0201] In Example 21, the subject matter of Examples 1-20 can include, wherein each of the optical fibers is a doped optical fiber.

[0202] In Example 22, the subject matter of Examples 2-3 can include the monolithic body being configured with a varying refractive index configuration to direct the output beam toward the phase mask at equal separation angles to create an output focus or focal region at the phase mask.

[0203] In Example 23, the subject matter of Example 22 can include a varying refractive index configuration in which the refractive index of the monolithic body is gradually changed toward a central axis or central plane to create a focusing effect.

[0204] Example 24 relates to a beam combining device for coherently combining multiple spectrally coherent optical beams, the beam combining device comprising: a plurality of optical fibers configured to output the coherent optical beams; a monolithic body that is at least partially transparent and has an input face and an output face, the monolithic body configured to be fixedly connected to the plurality of optical fibers and to direct the plurality of incident optical beams from the plurality of optical fibers from the input face through the monolithic body; and a phase mask configured to combine the output beams output from the output face of the monolithic body to form a single combined output beam output therefrom.

[0205] In Example 25, the subject matter of Example 24 may include that the monolithic body is configured so that beams directed therethrough exit from its output surface at the same exit separation angle as each other, and the phase mask is designed corresponding to the exit separation angle of the exit beams.

[0206] In Example 26, the subject matter of Examples 24-25 may include that the input surface of the monolithic body is configured such that the multiple optical fibers fixedly connected thereto are arranged at equal intervals and equal incident separation angles with respect to each other.

[0207] In Example 27, the subject matter of Examples 24-26 can include a phase mask etched or embossed into the output face of the monolithic body.

[0208] In Example 28, the subject matter of Examples 24-26 can include the phase mask having a mask layer adhered to the output surface of the monolithic body.

[0209] In Example 29, the subject matter of Examples 24-26 can include the phase mask being embedded in an optical element (OE).

[0210] In Example 30, the subject matter of Example 29 can include the OE being located separately from the output face of the monolithic body.

[0211] In Example 31, the subject matter of Example 29 can include the OE being integrated into the output face of the monolithic body.

[0212] In Example 32, the subject matter of Examples 24-31 may include the phase mask being further designed according to at least one of the following characteristics of each of the incident and / or exit beams: beam wavelength, beam wavelength band, beam phase, beam wavefront, beam waste, and beam radius.

[0213] In Example 33, the subject matter of Examples 24-32 can include wherein the phase mask comprises a phase mask.

[0214] In Example 34, the subject matter of Example 31 can include the phase mask comprising a diffraction grating.

[0215] In Example 35, the subject matter of Examples 24-34 can include the input face of the monolithic body being curved such that the relative angle of incidence between each pair of adjacent optical fibers is greater than zero to direct the beam toward a focal point or focal region at the output face of the monolithic body.

[0216] In Example 36, the subject matter of Examples 24-35 can include, wherein the input face of the monolithic body is flattened so that the beam from the optical fiber is incident on the monolithic body in a parallel manner.

[0217] In Example 37, the subject matter of Examples 24-36 can include, wherein the monolithic body includes at least one additional surface having a reflective interior that directs the beam from the input surface toward the output surface of the monolithic body by reflecting the beam toward the output surface.

[0218] In Example 38, the subject matter of Example 37 can include, wherein the reflective interior is formed by coating the interior of at least one additional surface with a reflective material.

[0219] In Example 39, the subject matter of Example 37 can include wherein the reflective interior is formed by attaching a reflective element to the interior of the at least one additional surface.

[0220] In Example 40, the subject matter of Examples 24-39 can include all of the optical fibers being designed to output optical beams at the same wavelength and / or wavelength band, such that all incident beams entering the monolithic body have the same wavelength and / or wavelength band.

[0221] In Example 41, the subject matter of Examples 24 to 40 can include, wherein each of the optical fibers is a double-clad optical fiber.

[0222] In Example 42, the subject matter of Examples 24 to 41 can include, wherein each of the optical fibers is a doped optical fiber.

[0223] Example 43 relates to a beam combining device for coherently combining multiple spectrally coherent optical beams emitted from multiple optical fibers, the beam combining device comprising a monolithic body that is at least partially transparent and has an input surface and an output surface, the input surface being configured to be fixedly connected to the multiple optical fibers and to direct multiple coherent incident optical beams incident from the multiple optical fibers toward its output surface, and the output surface having a phase mask configured to combine the beams directed from the input surfaces of the monolithic body to form a single combined output beam output therefrom.

[0224] In Example 44, the subject matter of Example 43 may include the monolithic body being configured with a varying refractive index configuration to direct the output beam toward the phase mask at equal separation angles to create an output focus or focal region on the phase mask.

[0225] In Example 45, the subject matter of Example 44 can include a varying refractive index configuration in which the refractive index in the monolithic body gradually changes toward a central axis or central plane to create a focusing effect.

[0226] Example 46 relates to a system for coherently beam combining multiple spectrally coherent optical beams, the system comprising: a plurality of light sources; a plurality of optical fibers, each configured to guide light generated from one of the plurality of light sources; and a coherent combining device, the coherent combining device comprising a monolithic body that is at least partially transparent and has an input surface and an output surface, the monolithic body configured to be fixedly connected to the plurality of optical fibers and to direct the plurality of coherent incident optical beams from the plurality of optical fibers from the input surface toward the output surface; and the coherent combining device including a phase mask configured to combine the output beams output from the output surface of the monolithic body to form a single combined output beam output therefrom, wherein the monolithic body is configured so that the beams directed therethrough exit from its output surface at the same exit separation angle as each other, and the phase mask is designed to correspond to the exit separation angle of the output beams.

[0227] Example 47 relates to a beam combining device for coherent beam combining of multiple spectrally coherent optical beams, comprising: a monolithic body that is at least partially transparent and has at least an input surface and an output surface, the input surface being configured and positioned to direct multiple coherent incident optical beams through optical paths within the monolithic body toward the output surface; and a phase mask configured to combine output beams exiting the output surface of the monolithic body to form a single combined output beam output therefrom.

[0228] Example 48 is a system for coherent beam combining of multiple spectrally coherent optical beams, comprising a plurality of coherent beam combining (CBC) devices, each of which is an at least partially transparent monolithic body having an input surface and an output surface, the monolithic body configured to fixedly connect to a plurality of optical waveguides and direct a plurality of incident optical beams from the plurality of optical waveguides from the input surface toward the output surface by focusing the incident optical beams at focal points located on a focal plane, and a CBC device located on the focal plane and configured to combine the output beams exiting from the output surface of the monolithic body to form a single coherent beam combining device output therefrom. and at least one output optical waveguide connectable to an output side of the phase mask of at least some of the CBC devices, the output optical waveguide being located at a focus of the output optical beam so as to direct the combined output optical beam therethrough, wherein at least one of the multiple CBC devices is connected via a respective input face to the output optical waveguides of at least some of the other CBC devices to form a network of CBC devices for additional power scaling of at least some of the incident optical beams.

[0229] Example 49 relates to a system for combining optical beams, the system comprising: a plurality of coherent beam combining (CBC) devices, each configured to combine multiple coherent optical beams and output a combined output optical beam, the CBC devices each configured to combine optical beams of different wavelengths or wavelength ranges from one another and output a combined output optical beam; and at least one spectral beam combining (SBC) device configured and positioned relative to the plurality of CBC devices to combine spectrally differentiated incident optical beams emitted from the plurality of CBC devices into a single combined multispectral optical beam.

[0230] Example 50 relates to a spectral beam combining (SBC) device for combining multiple spectrally differentiated incident optical beams emitted from multiple optical fibers, the SBC device comprising a monolithic body that is at least partially transparent and has an input surface, a diffraction surface, and an output surface that are fixedly connected or connectable to multiple optical fibers, the monolithic body being configured to direct an incident optical beam entering the interior through the input surface through multiple diffraction optical paths inside the monolithic body by directing the incident optical beam to impinge on the diffraction surface at least two times to combine the incident optical beams into a single multi-spectral combined output optical beam and exit the monolithic body through the output surface.

[0231] In Example 51, the subject matter of Example 50 may include that the monolithic body is configured to combine incident optical beams by directing them through multiple diffraction optical paths so that all optical beams exit the monolithic body through the output surface on mutually parallel exit trajectories to form a combined output incident optical beam.

[0232] In Example 52, the subject matter of Examples 50-51 may include that the monolithic body further has at least one reflective surface positioned to reflect the optical beam at least once to direct it toward the diffractive surface.

[0233] In Example 53, the subject matter of Example 52 can include one of the at least one reflective surfaces being positioned parallel to and at an angle relative to the diffractive surface.

[0234] In Example 54, the subject matter of Example 52 can include one of the at least one reflective surface being positioned at an angle relative to the diffractive surface.

[0235] In Example 55, the SBC devices of Examples 50-51 may further include multiple reflective surfaces configured for total internal reflection (TIR) ​​or partial internal reflection (PIR).

[0236] In Example 56, the subject matter of Example 55 may include that the output surface includes a reflective region and a transparent region, and is positioned to reflect an optical beam that impinges on the reflective region back into the monolithic body so that it can be redirected towards the diffractive surface, and to allow an optical beam directed towards the transparent region to exit the monolithic body therefrom.

[0237] In Example 57, the subject matter of Examples 50-56 can include all incident optical beams entering the monolithic body through its input face on trajectories that are parallel to one another.

[0238] In Example 58, the subject matter of Example 57 can include the trajectory of the incident optical beam when incident on the monolithic body being at an angle with respect to the diffractive surface.

[0239] In Example 59, the subject matter of Examples 50-58 can include the monolithic body having additional surfaces to form a three-dimensional (3D) object.

[0240] In Example 60, the subject matter of Examples 50 to 59 can include that at least the diffractive surface of the monolithic body is flat.

[0241] In Example 61, the subject matter of Example 60 can include the input surface and the output surface being flat.

[0242] In Example 62, the subject matter of Examples 52-54 can include the monolithic body configuration and the optical fiber connection thereto being designed to direct incident optical beams that are parallel to one another through a dual optical path, such that the incident beam is directed from the input surface towards the diffractive surface, from the diffractive surface to at least one reflecting surface, from the at least one reflecting surface back to the diffractive surface, and from the diffractive surface to the output surface.

[0243] In Example 63, the subject matter of Examples 50-62 may include the incident optical beams having different wavelengths or wavelength bands that are spectrally differentiated from one another, and the phase mask is configured with respect to the difference between the wavelengths of the incident optical beams.

[0244] In Example 64, the subject matter of Example 63 can include the incident optical beams being of wavelengths with equal spectral separation.

[0245] In Example 65, the subject matter of Examples 63-64 may include that the phase mask of the diffractive surface includes at least one of a diffraction grating mask and a prism.

[0246] In Example 66, the subject matter of Example 65 can include the at least one diffraction grating mask being configured to correspond to the geometric shape and dimensions of the monolithic body and the wavelength of the incident optical beam.

[0247] In Example 67, the subject matter of Examples 50-66 can include a phase mask etched, embossed, or attached to one side of the monolithic body to form a diffractive surface.

[0248] Example 68 relates to a spectral beam combining (SBC) device for combining multiple spectrally differentiated incident optical beams, comprising: a plurality of optical fibers that output the multiple spectrally differentiated optical beams from an output end; and a monolithic body that is at least partially transparent and has an input surface, a diffractive surface, and an output surface that are fixedly connected to the multiple optical fibers, wherein the monolithic body is configured to direct the incident optical beam incident through the input surface through multiple diffractive optical paths within the monolithic body by directing the incident optical beam so that it impinges on the diffractive surface at least twice, thereby combining the incident optical beams into a single multispectral combined output optical beam and outputting it from the monolithic body through the output surface.

[0249] In Example 69, the subject matter of Example 69 can include wherein the optical fiber comprises a doped optical fiber and / or a double-clad optical fiber.

[0250] In Example 70, the subject matter of Examples 68-69 can include the optical fiber being bonded, welded, or glued to the input face of the monolithic body.

[0251] In Example 71, the subject matter of Example 70 may include that the input surface of the monolithic body is flat and that the optical fiber is fixedly connected thereto so that the incident beams enter therethrough on mutually parallel incident trajectories.

[0252] In Example 72, the subject matter of Examples 68 to 71 may include connecting the optical fibers to the input surface at equal intervals.

[0253] In Example 73, the subject matter of Examples 68 to 72 may include, wherein the phase mask of the diffractive surface includes at least one of a diffraction grating mask and a prism.

[0254] In Example 74, the subject matter of Examples 68-73 may include the monolithic body further comprising at least one reflective surface positioned to reflect the optical beam at least once to direct the optical beam toward the diffractive surface.

[0255] In Example 75, the subject matter of Examples 68-74 may include the monolithic body being configured to combine incident optical beams to form a combined output optical beam by directing the optical beams through multiple diffractive optical paths such that all of the optical beams exit the monolithic body through the output surface on mutually parallel exit trajectories.

[0256] Example 76 relates to a method for coherent beam combining (CBC), comprising: providing a CBC device having a monolithic body and a phase mask, wherein the phase mask is configured to combine coherent optical beams; directing multiple coherent optical beams toward the monolithic body of the CBC device; directing the multiple coherent optical beams inside the monolithic body of the CBC device so as to converge at a focus defining a focal plane, wherein the phase mask of the CBC device is located on the focal plane; combining the multiple coherent optical beams impinging on the phase mask; and outputting a single coherent combined output optical beam.

[0257] Example 77 relates to a method for spectral beam combining (SBC) of spectrally differentiated optical beams, the method including: providing an SBC device including a monolithic body having at least an input surface, an output surface, and a diffraction surface; directing multiple spectrally differentiated optical beams into the monolithic body of the SBC device through the input surface; combining the multiple spectrally differentiated optical beams inside the monolithic body of the SBC device by directing them through multiple diffraction optical paths, made possible by directing the multiple spectrally differentiated optical beams to impinge on the diffraction surface at least twice; and outputting a single multispectral combined output optical beam.

[0258] Example 78 is a method for combining multiple optical beams, the method comprising: providing a first set of coherent beam combining (CBC) devices, each configured to combine coherent optical beams directed thereto and to output a coherent combined output optical beam; providing at least one additional combining device configured to combine the optical beams; directing the combined output optical beams output by the first set of CBC devices toward an input face of the at least one additional combining device; combining the directed combined output optical beams output by the first set of CBC devices by the at least one additional combining device; and outputting a single combined final output optical beam and directing it outward from the at least one additional combining device.

[0259] In Example 79, the subject matter of Example 78 may include, wherein a first set of CBC devices is configured to combine and output optical beams of overlapping, similar, or identical wavelengths or wavelength bands, and at least one additional combining device is a CBC device.

[0260] In Example 80, the subject matter of Example 78 may include, wherein the first set of CBC devices is configured to output a spectrally differentiated output optical beam, and the at least one additional combining device is a spectral beam combining (SBC) device.

[0261] While the present invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplification of some embodiments.

[0262] In the discussion, unless otherwise specified, adjectives such as "substantially" and "about" that modify the state or relationship characteristic of a feature or features of an embodiment of the invention should be understood to mean that the state or characteristic is defined within acceptable tolerances allowed for operation of the embodiment for its intended use.

[0263] Unless otherwise specified, the terms "substantially," "about," and / or "near" with respect to a magnitude or value may imply an inclusive range of -10% to +10% of the respective magnitude or value.

[0264] When a claim or the specification refers to "a" or "an" element, component, object, attribute, property, and / or characteristic, it is to be understood that such a reference is not to be construed as referring to only one of the elements. Thus, for example, a reference to "an element" or "at least one element" can also encompass "one or more elements" or "at least one element," etc.

[0265] Terms used in the singular shall include the plural unless expressly stated otherwise or the context otherwise requires.

[0266] In the description and claims of this application, the verbs "comprise," "include," and "have," as well as their conjugations, are used to indicate that the object(s) of the verb are not necessarily an exhaustive list of components, elements, or parts of the subject(s) of the verb.

[0267] Unless otherwise specified, the use of the term "and / or" between the last two members of a list of selection options indicates that selecting one or more of the listed options is appropriate and may be implemented. Furthermore, the use of the term "and / or" may be used interchangeably with the terms "at least one of," "any one of," or "one or more of," followed by a list of various options.

[0268] It will be understood that certain features of the invention that are, for clarity, described in the context of separate embodiments or examples, may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the invention that are described in the context of a single embodiment, example, and / or option may also be provided separately or in any suitable sub-combination, or as suitable with any other described embodiment, example, or option of the invention. Certain features described in the context of various embodiments, examples, and / or optional implementations should not be considered essential features of those embodiments, examples, and / or optional implementations, unless the embodiments, examples, and / or optional implementations would not operate without those elements.

[0269] It should be noted that the terms "in some embodiments," "according to some embodiments," "according to some embodiments of the invention," "for example," "eg," "for instance," and "optionally" can be used interchangeably herein.

[0270] The number of elements shown in the figures should not be construed as limiting in any way but is for illustrative purposes only.

[0271] Throughout this application, various embodiments may be presented and / or related in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the embodiments. Accordingly, the description of a range should be considered to have specifically disclosed all possible subranges as well as individual numerical values ​​within that range. For example, description of a range such as 1 to 6 should be considered to have specifically disclosed subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numerical values ​​within that range, e.g., 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Claims

1. 1. A method for combining multiple light beams, comprising: providing a first set of coherent beam combining (CBC) devices, each CBC device configured to combine directed coherent optical beams and output a coherent combined output optical beam; providing at least one additional combining device configured to combine a plurality of light beams; directing a combined output optical beam output by each CBC device of the first set of CBC devices toward an input face of the at least one additional combining device; The at least one additional composite device comprises an at least partially transparent monolithic body, the monolithic body comprising: An input surface; a diffractive surface; an output surface; the monolithic body is configured to direct incident optical beams incident through the input surface to impinge on the diffractive surface, thereby directing the incident optical beams through a diffractive optical path within the monolithic body, combining the incident optical beams into a single combined output optical beam that exits the monolithic body through the output surface; combining, by the at least one additional combining device, the directed combined output optical beams output by the first set of CBC devices; outputting a single combined final output optical beam and directing it externally from the at least one additional combining device. A method characterized by:

2. at least one CBC device of the first set of CBC devices comprises a monolithic body that is at least partially transparent and has at least an input face and an output face; the input face is configured to fixedly couple to a plurality of optical fibers and direct a plurality of coherent incident beams from the plurality of optical fibers through the monolithic body; the at least one CBC device of the first set of CBC devices further comprising a phase mask configured to combine output beams exiting the output faces of the monolithic body to form a single combined output beam output therefrom.

2. The method of claim 1 .

3. at least one CBC device of the first set of CBC devices is connectable to a plurality of optical fibers from an input face of the respective CBC device; 2. The method of claim 1 .

4. the combined output optical beam output by each CBC device of the first set of CBC devices is directed to the at least one additional combining device via a plurality of waveguides; 2. The method of claim 1 .

5. 1. A system for combining multiple light beams, comprising: a first set of coherent beam combining (CBC) devices, each CBC device configured to combine directed coherent optical beams and output a coherent combined output optical beam; at least one additional combining device configured to combine a plurality of light beams; the system is configured to direct a combined output optical beam output by each CBC device of the first set of CBC devices toward an input face of the at least one additional combining device, and combine the directed combined output optical beams output by the CBC devices of the first set by the at least one additional combining device to output a single combined final output optical beam; The at least one additional composite device comprises an at least partially transparent monolithic body, the monolithic body comprising: An input surface; a diffractive surface; an output surface; the monolithic body is configured to direct incident optical beams incident through the input surface to impinge on the diffractive surface, thereby directing the incident optical beams through a diffractive optical path within the monolithic body, combining the incident optical beams into a single combined output optical beam that exits the monolithic body through the output surface; A system characterized by:

6. at least one CBC device of the first set of CBC devices comprises a monolithic body that is at least partially transparent and has at least an input face and an output face; the input face is configured to fixedly couple to a plurality of optical fibers and direct a plurality of coherent incident beams from the plurality of optical fibers through the monolithic body; the at least one CBC device of the first set of CBC devices further comprising a phase mask configured to combine output beams exiting the output faces of the monolithic body to form a single combined output beam output therefrom.

6. The system of claim 5.

7. at least one CBC device of the first set of CBC devices is connectable to a plurality of optical fibers from an input face of the respective CBC device; 6. The system of claim 5.

8. the combined output optical beam output by each CBC device of the first set of CBC devices is directed to the at least one additional combining device via a plurality of waveguides; 6. The system of claim 5.

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