Method and system for microlens array-based alignable optical transmitter / receiver

Abstract

A laser communication terminal comprises a laser, a receiver, and a photonic integrated circuit (PIC) optically coupled to the laser and receiver. The laser communication terminal also includes multiple optical fibers. Each of the multiple optical fibers is optically coupled to the PIC and to a microlens array. Each of the multiple optical fibers is attached to the microlens array. The PIC can include multiple waveguides and multiple phase-matching elements, and each of the multiple waveguides can be optically coupled to a corresponding phase-matching element.

Description

Cross-reference to related applications

[0001] This application claims priority from US Provisional Application No. 63 / 6651,150, filed on June 27, 2025, entitled “Method and System for Microlens-Array-Based Steerable Optical Transceiver”, the disclosure of which is hereby fully incorporated by reference for all purposes. Background of the invention

[0002] Laser communication between satellites has been used to transmit information at high data rates. NASA's Laser Communication Relay Demonstration (LCRD), launched in 2021, aims to demonstrate the long-term reliability of two-way laser relay systems for both low-Earth-space and deep-space missions. Several commercial satellite constellations are attempting to incorporate laser communication for inter-satellite links and to create space-based optical mesh networks.

[0003] Despite the progress made in the field of laser communication between satellites, there is still a need for improved methods and systems regarding optical communication systems. Brief description of the invention

[0004] The present disclosure relates generally to methods and systems relating to optical systems suitable for optical communication. In particular, embodiments of the present invention provide laser communication transmitters / receivers that can be used for transmitting and receiving optical communication signals between satellites. The disclosure is applicable to a multitude of applications in lasers and optics, including other optical communication implementations.

[0005] Numerous advantages over conventional technology are achieved by the present disclosure. For example, embodiments of the present invention enable high-speed communication using systems that are more cost-effective and lightweight compared to conventional approaches. These and other embodiments of the disclosure, along with many of their advantages and features, are described in more detail in the following description and the corresponding drawings. Brief description of the drawings Fig. Figure 1 is a simplified schematic diagram showing a satellite constellation with laser transmitters / receivers according to an embodiment of the present invention. Fig. Figure 2 is a simplified schematic diagram showing bidirectional laser communication between two satellites according to an embodiment of the present invention. Fig. Figure 3 is a simplified schematic diagram showing components of a satellite-based bidirectional laser communication system according to an embodiment of the present invention. Fig. Figure 4A is a simplified schematic diagram of a laser communication terminal device according to an embodiment of the present invention. Fig. Figure 4B is a simplified schematic diagram showing components of a photonic integrated circuit according to an embodiment of the present invention. Fig. Figure 5 is a simplified schematic diagram of a laser communication terminal device with a fill factor correction plate according to an embodiment of the present invention. Fig. Figure 6A is a simplified schematic diagram of a microlens array according to an embodiment of the present invention. Fig. Figure 6B is a simplified schematic diagram of the alignment of an optical fiber with a lenslet in a microlens array according to an embodiment of the present invention. Fig. Figure 7A is a simplified schematic diagram showing the alignment of an optical fiber with a microlens array according to an embodiment of the present invention. Fig. Figure 7B is a simplified schematic diagram showing the alignment of an optical fiber with a microlens array in a variable-angle implementation according to an embodiment of the present invention. Fig. Figure 8 is a simplified schematic diagram of a laser communication terminal device according to an alternative embodiment of the present invention. Fig. Figure 9 is a simplified flowchart showing a method for performing inter-satellite communication according to an embodiment of the present invention. Fig. Figure 10A is a simplified cross-sectional diagram showing a silicon photonics substrate, an optical prism and dual microlens arrays according to an embodiment of the present invention. Fig. Figure 10B is a simplified cross-sectional diagram showing a silicon photonics substrate, an optical prism and dual microlens arrays according to an embodiment of the present invention. Fig. Figure 11 is a simplified cross-sectional diagram showing a silicon photonics substrate, several optical input fibers and a spatially separated, fiber-reinforced microlens array according to an embodiment of the present invention. Fig. Figure 12 is a simplified top-down view showing a silicon photonics substrate, several optical input fibers and a high-density optical coupler according to an embodiment of the present invention. Detailed description of the invention

[0006] The present disclosure relates generally to methods and systems relating to optical systems suitable for optical communication. In particular, embodiments of the present invention provide laser communication transmitters / receivers that can be used for transmitting and receiving optical communication signals between satellites. The disclosure is applicable to a multitude of applications in lasers and optics, including other optical communication implementations.

[0007] Fig. Figure 1 is a simplified schematic diagram showing a satellite constellation with laser transmitters / receivers according to an embodiment of the present invention. As shown in the Fig. In the satellite constellation 100 illustrated in Figure 1, two satellites (i.e., satellite 110 and satellite 120) communicate with each other via one of four optical communication channels. In the embodiment shown, the mode of communication between satellites is laser-based. Although communication with ground stations (not shown) can be carried out using radio frequency (RF) communication systems, communication between satellites, also referred to as in-layer communication or inter-satellite communication, is carried out using optical communication systems, in particular laser communication systems. The inventors have determined that optical satellite-to-satellite communication significantly improves constellation performance compared to RF-based satellite-to-satellite communication because, in many cases, the vast majority of the data is transmitted in the layer, i.e.,The communication occurs between satellites, and not between satellites and ground stations. Therefore, RF-based communication between satellites and ground stations can be used in conjunction with laser-based optical communication between satellites. Embodiments of the present invention provide laser communication terminals suitable for laser-based optical communication between satellites.

[0008] In the Fig. Figure 1 shows four optical communication channels associated with satellite 110, namely a first optical communication channel 112, a second optical communication channel 114, a third optical communication channel 116, and a fourth optical communication channel 118, and four optical communication channels associated with satellite 120, namely a fifth optical communication channel 122, a sixth optical communication channel 124, a seventh optical communication channel 126, and an eighth optical communication channel 128. However, in other embodiments, three or fewer optical communication channels per satellite may be used, while in alternative embodiments, more than four optical communication channels per satellite may be used. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0009] Fig. Figure 2 is a simplified schematic diagram showing bidirectional laser communication between two satellites according to an embodiment of the present invention. Fig. Satellite 110 transmits data to satellite 120 using laser communication device 210, and satellite 120 receives data from satellite 110 using laser communication device 220. Although in Fig. The fact that unidirectional communication is depicted here is for illustrative purposes only, and bidirectional communication is enabled by the various embodiments discussed herein. In particular, as explained in more detail below, Fig. 4 discussed, the laser communication terminals discussed herein provide bidirectional communication by means of a photonic integrated circuit including beam splitters and phase matching elements and several optical fibers bonded to a microlens array in such a way that the light can be guided through the optical fibers and the microlens array and received by the microlens array and the optical fibers.

[0010] Fig. Figure 3 is a simplified schematic diagram showing components of a satellite-based bidirectional laser communication system according to an embodiment of the present invention. With regard to Fig. Figure 3 shows two satellites, namely satellite 310 and satellite 320. Satellite 310 and satellite 320 can access satellites 110 and 120. Fig. 1 and Fig. 2. Each satellite can be identical or different depending on the specific application. To implement bidirectional communication between satellite 310 and satellite 320, and with reference to satellite 310, each satellite includes a laser communication terminal 305 mounted on a chassis 312. The laser communication terminal 305 includes a laser source 314, for example, a single-mode semiconductor laser, which outputs, for example, 100 mW, 500 mW, 1 W, 2 W, 5 W, or the like. The power may be adjustable in some embodiments. The laser communication terminal 305 also includes a photonic integrated circuit (PIC) 315 and an optical fiber bundle containing several optical fibers 316. The light from the laser source 314 is fed into the PIC 315, which includes several waveguides, beam sections, and phase-matching elements.As an example, a single input port could receive the light from the laser source 314 and use a fanout network to split the single input into a large number of laser signals, for example, 2000 laser signals, each of which passes through a separate waveguide of the PIC. Each of these waveguides can be optically coupled to a phase-matching element, which is capable of adjusting the phase of the laser signal passing through the corresponding waveguide. After phase matching, the phase-matched laser signal can pass through another waveguide, which forms an output port of the PIC. In this example, the light from the laser source, split into 2000 laser signals, would be coupled to 2000 output waveguides, coupled to 2000 output ports, which in turn would be coupled to 2000 optical fibers, comprising the multiple optical fibers 316.

[0011] The multiple optical fibers 316 are bonded, e.g., laser-welded, to a microlens array 317 as described in more detail in conjunction with Fig. 6A and Fig. 6B is discussed. An optional set of optical transmitter / receiver optics 318 is optically coupled to the microlens array 317. Like satellite 310, satellite 320 includes a laser communication terminal 307 mounted on the chassis 322. The laser communication terminal 307 includes a laser source 324, a PIC 325, an optical fiber bundle containing multiple optical fibers 326, a microlens array 327, and an optional set of optical transmitter / receiver optics 328.

[0012] As discussed in more detail herein, optical signals generated at satellite 310 can be transmitted to satellite 320 and optical signals generated at satellite 320 can be transmitted to satellite 310 to implement bidirectional communication. Thus, it will be evident that, although the above discussion focuses on the transmission of signals from satellite 310 and the reception of signals at satellite 320, this discussion is merely exemplary and bidirectional communication is made possible by embodiments of the present invention.

[0013] Fig. Figure 4A is a simplified schematic diagram of a laser communication terminal 400 according to an embodiment of the present invention. As shown in Figure 4A, the laser communication terminal 400 is a laser communication terminal 400 according to an embodiment of the present invention. Fig. As shown in Figure 4A, the laser communication terminal 400 includes a laser source 410 used as a transmitter and a detector 416 used as a receiver. Thus, the laser communication terminal 400 implements an optical transmitter / receiver. Both the laser source 410, used as a transmitter, and the detector 416, used as a receiver, are optically coupled to the photonic integrated circuit (PIC) 420, which uses optical dividers and phase-matching elements to implement phase control in order to split the signal received from the laser transmitter and provide output signals to the multiple optical fibers 430, with control over the relative phases of each of the signals output by the PIC 420 and transmitted through the multiple optical fibers 430 during transmission operation.Input light from laser source 410 is received at input port 414 in transmit mode, and output light generated by the PIC in receive mode is output at output port 418. An optical isolator 412 is placed between laser source 410 and input port 414 of the PIC 420 to prevent optical feedback from the PIC 420 from affecting the performance of laser source 410. Further descriptions regarding waveguides, beam splitters / combiners, and phase-matching elements are provided below. Fig. 4B provided.

[0014] As above with reference to Fig. As discussed in section 3, during transmission operation, the input signal generated by the laser source 410 is split into multiple transmission signals by means of waveguides and beam splitters implemented in the PIC 420. Each transmission signal passing through a waveguide in the PIC is coupled into a corresponding phase-matching element, which operates under the control of the controller 422. The phase-matching elements enable control of the phase of each output provided by the PIC, and consequently, the generation of a coherent array of outputs from the microlens array 432, represented by the output beam 434.

[0015] During receive operation, the PIC 420 uses optical combiners and / or phase control to combine signals received from the multiple optical fibers into a detection signal provided to the detector 416, also referred to as the receiver. As those skilled in the art will expect, the beam splitters used to generate multiple optical signals from a single input signal will conversely operate by combining multiple optical signals into a single output signal that can be fed to the detector 416.

[0016] As discussed above, the optical signals transmitted during receive operation are phase-matched, both to ensure spatial coherence and to provide a specific shape for the outgoing optical beamfront represented by the output beam 434. In addition to phase control corresponding to spatial coherence between the individual signals emitted by the microlenses of the microlens array, the phase-matching elements can be used to align the output beam 434 by introducing a tilt in its phase. Thus, in embodiments of the present invention, beam alignment is implemented in a solid-state structure. The absence of any moving parts in embodiments of the present invention provides significant advantages not available with conventional motion-based telescopes.

[0017] The PIC provides optical distribution functionality via waveguides and phase shifters. The PIC's distribution network is shown as consisting of a single input fiber (i.e., from the laser transmitter) and multiple output fibers (i.e., attached to or interfacing with the microlens array). As an example, in one embodiment, the multiple output fibers are laser-welded to the microlens array to avoid the use of epoxy, which can affect the optical path. In some examples, the number of output fibers is on the order of thousands (e.g., ~4000), but other embodiments use a different number of output fibers. It should be noted that the large aperture associated with the microlens array provides low divergence over the distances between satellites compared to the aperture of a semiconductor laser, and consequently, a small far-field pattern.Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0018] Fig. Figure 4B is a simplified schematic diagram showing components of a photonic integrated circuit according to an embodiment of the present invention. As shown in Fig. As shown in Figure 4B, the PIC 470 receives an optical signal from the laser source 410 at input port 414. The PIC 470 includes beam splitters 472, 474, and 476, which, in this embodiment, split the optical signal into four optical signals. As will be apparent to those skilled in the art, when the PIC 470 receives returning light, the beam splitters will act as optical combiners, combining multiple optical signals into a single signal. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0019] The PIC 470 also includes phase-matching elements 482, 484, 486, and 488, which can be used to adjust the phase of the light passing through the waveguide 481 to match each phase-matching element. As a result, coherent light provided by the laser source 410 can be split into multiple optical signals, which can be called input signals with respect to the phase-matching elements. All of these signals can be spatially coherent when output from the input / output ports 492, 494, 496, and 498, because each of these phase-matching elements can be used to produce phase-matched input signals suitable as output from the PIC 470. As discussed above, although the operation of the PIC 470 in Fig. Figure 4B shows the PIC 470 in transmit mode. It should be noted that the PIC 470 can also be operated in receive mode, where the optical signals are received at output / input ports 492-498, phase-matched using phase-matching elements 482-488, and combined using beam splitters 476, 474, and 472. In receive mode, the optical signals are output at output port 418.

[0020] Intersymbol interference (ISI) can occur due to distortion of the waveform of the incoming beam, distortion of the angular spectrum of the incoming beam received by the array, and / or the Doppler effect, which exhibits a strong angular dependence. In any case, the presence of an input that varies across the receiving array results in different delay times in the received data for each microlens element. When these signals are combined, either in an array of detectors or a single detector after being returned through the photonic silicon chip, the delay time between the arms will lead to a loss of synchronization in the signal from each arm. If the bit slots of the various data streams do not overlap, the effect is that energy spills over from one slot to the adjacent slot, which is commonly known as intersymbol interference.According to embodiments of the present invention, the phase shifters in the PIC can be used to modify the optical path length in each arm, i.e., each waveguide of the PIC, thereby mitigating the effect of intersymbol interference.

[0021] In embodiments of the present invention, in which, as in Fig. As shown in Figure 4A, when a single detector is used to receive the signal, the light from each arm of the fiber array is preferably added coherently and constructively by a series of combiners to avoid loss of the received photon field. A plane wave incident on the array will produce waveforms with the same phase in each optical fiber, allowing all the incident power to be received constructively without loss at the detector. Wavefront distortion present in the incoming beam received by the array will lead to a different phase in each fiber port, resulting in only partially constructive or even completely destructive interference at the combiner, which in turn leads to optical signal loss at the detector.According to embodiments of the present invention, the phase shifters in each channel can be used to align the phases in each arm in order to mitigate a loss at the detector that would otherwise occur due to aberrations of the incoming beam.

[0022] Referring to Fig. 4A enables the bonding of the optical fibers 430 to the output ports of the PIC 420 at one end and to the microlens array 432 at the other end in a monolithic, epoxy-free structure. In some embodiments, the optical fibers are optically bonded, fused, or welded (e.g., laser-welded) to the PIC 420 and the microlens array 432, providing reliability and alignment accuracy not guaranteed in some other approaches. In particular, the entire optical path from the laser to the input ports of the PIC, internally within the PIC to the output ports of the PIC, through the optical fibers, and to the microlens array can be monolithic; the entire system from the laser to the microlens array can consist solely of glass, semiconductor, or other suitable material.

[0023] A wide variety of optical fibers can be used in the system discussed herein, including single-mode fibers such as SMF-28, available from Corning, Inc., in Corning, NY. In embodiments using single-mode fibers, the lasers and input ports of the PIC can be mode-matched to the single-mode fibers, although this is not required, and non-mode-matched implementations are also included within the scope of the present invention. A variety of input coupling elements can be used to input light from the laser to the PIC, including direct bonding, grating couplers (also called diffraction grating couplers), holographic optical elements, 45° etched mirrors, and the like.Lattice couplers are merely one example of input coupling elements that can be used to couple light into optical waveguides present in the PIC, and the discussion of lattice couplers as one example does not exclude the use of other forms of input coupling elements in various embodiments of the present invention.

[0024] Embodiments of the present invention can employ one of several structures to bond the optical fibers 430 to the output ports of the PIC 420. Exemplary structures are described with respect to Fig. 1A - 12 and US patent application No. 19 / 076,838 are discussed, the disclosure of which is hereby included by reference for all purposes.

[0025] Referring to Fig. System 10A comprises a silicon photonic substrate 1010, which includes the input coupling elements 1012a, 1012b, 1012c, 1012d, and 1012e, as well as optical waveguides represented by the optical waveguide 1014. Other elements, including both active and passive devices, may be provided on the photonic silicon substrate 1010, as will be expected by those skilled in the art.

[0026] As in Fig. As shown in Figure 10A, multiple optical fibers 1020 are used to provide multiple optical inputs, represented by optical fibers 1022a, 1022b, 1022c, 1022d, and 1022e. Although in Fig. As shown in Figure 10A with five optical fibers, embodiments of the present invention will generally employ a two-dimensional array of optical fibers arranged both in and into the plane of the drawing. The optical fibers are, for example, optically bonded, fused, or welded (for example, laser-welded) to a microlens array (MLA), and the component formed by the optical fibers and the MLA can be referred to as a fiber-enclosed MLA. As shown in Figure 10A, the optical fibers are arranged in a two-dimensional array of optical fibers arranged in the plane of the drawing. The optical fibers are, for example, optically bonded, fused, or welded (for example, laser-welded) to a microlens array (MLA), and the component formed by the optical fibers and the MLA can be referred to as a fiber-enclosed MLA. Fig. As shown in Figure 10A, the MLA 1025 can contain multiple lenslets 1026. Each lenslet 1026 can be described as a microlens. Each of the lenslets can serve to collimate light emitted from a corresponding optical fiber.

[0027] The one in the Fig. The optical coupler 1040 used in the embodiment shown in Figure 10A is a prism with three planar surfaces: input surface 1042, hypotenuse surface 1044, and output surface 1046. A second MLA 1065 is arranged between the optical coupler 1040 and the photonic silicon substrate 1010 and focuses light emitted by the optical coupler 1040 onto input coupling elements, which are described in more detail herein. The space between the output surface 1046 and the photonic silicon substrate 1010 can be adjusted to a predetermined distance using a suitable spacer. Those skilled in the art will be aware of many variations, modifications, and alternatives.

[0028] Referring to Fig. In 10A, the optical signal emitted by the optical fiber 1022c passes through the microlens 1028 and is collimated, as represented by light rays 1027. After passing through to the hypotenuse surface 1044, the light rays 1027 are reflected by TIR and produce light rays 1029. The light rays 1029 are focused by the microlens 1063 and converge as they pass through to the input coupling element 1012c. Thus, in this embodiment, one-to-one mapping is achieved by focusing the light emitted by the optical fiber 1022c onto the input coupling element 1012c. In this way, the optical mode passing through the optical fiber is matched to the optical mode coupled in by the input coupling element, and this in turn is matched to the optical waveguide.

[0029] In some embodiments, the microlenses in the MLA 1025 may be identical to each other, and the microlenses in the MLA 1035 may also be identical to each other. In other embodiments, each of the microlenses in the MLA 1025 and / or each of the microlenses in the MLA 1035 may have unique optical parameters, including size, focal length, asphericity, and the like. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0030] Fig. Figure 10B is a simplified cross-sectional diagram showing a silicon photonics substrate, an optical prism, and dual microlens arrays according to an embodiment of the present invention. The diagram shown in Figure 10B is a simplified cross-sectional diagram showing a silicon photonics substrate, an optical prism, and dual microlens arrays according to an embodiment of the present invention. Fig. The system shown in 10B is related to the one in Fig. The system elements shown in 10A are common, and those relating to Fig. The description provided in section 10A is appropriately applied to the information in Fig. System shown in 10B is applicable.

[0031] Referring to Fig. System 10B includes several optical fibers 1020, which are used to provide multiple optical inputs. The optical fibers 1050 are attached to the MLA 1055, and the component formed by the optical fibers and the MLA can be referred to as a fiber-optic MLA. As shown in Fig. As shown in Figure 10B, the MLA 1055 can have multiple lenslets 1056, also called microlenses, and the MLA 1055 can be combined with the one shown in Figure 10B. Fig. The MLA 1025 system shown in Figure 10A shares similar characteristics. System 1050 can be used in conjunction with a photonic silicon substrate (not shown), as described in more detail herein.

[0032] The one in the Fig. The optical coupler 1060 used in the embodiment shown in Figure 10B is a prism with three planar surfaces. Collimated light falls on the input surface 1062, is reflected by TIR at the hypotenuse surface 1064, and is emitted through the output surface 1066. To provide a predetermined distance between the MLA 1055 and the input surface 1062, spacers 1057 are arranged around the circumference of the MLA 1055. The spacers 1057 can be butt-jointed to the optical coupler 1060, welded to the optical coupler 1060, or the like. In some embodiments, the spacers 1057 are part of the MLA 1055, whereas in other embodiments, the spacers 1057 are provided as a separate component, for example, as an annular structure with a rectangular shape when viewed from above.Furthermore, to provide a predetermined distance between the MLA 1065 and the output surface 1066, spacers 1059 are arranged around the circumference of the MLA 1065. The spacers 1059 can be butt-jointed to the optical coupler 1060, welded to the optical coupler 1060, or the like. In some embodiments, the spacers 1059 are part of the MLA 1065, whereas in other embodiments, the spacers 1059 are provided as a separate component, for example, as an annular structure with a rectangular shape when viewed from above.

[0033] Fig. Figure 11 is a simplified cross-sectional diagram showing a silicon photonics substrate, several optical input fibers, and a spatially separated, fiber-reinforced microlens array according to an embodiment of the present invention. Referring to Fig. 11 The system 1100 includes a silicon photonic substrate 1110, which includes input coupling elements 1112a, 1112b, 1112c, 1112d and 1112e, as well as optical waveguides represented by the optical waveguide 1114.

[0034] As in Fig. As shown in Figure 11, multiple optical fibers 1120 are used to provide multiple optical inputs, illustrated by optical fibers 1122a, 1122b, 1122c, 1122d, and 1122e. The optical fibers will generally be a two-dimensional array of optical fibers arranged both in and into the plane of the drawing. Each of the optical fibers is, for example, optically bonded, fused, or welded (for example, laser-welded) to MLA 1030, which is separated from the silicon photonic substrate 1110 by a predetermined distance by spacers 1132 arranged around the circumference of MLA 1130. The spacers 1132 can be butt-jointed to MLA 1130, welded to MLA 1130, or the like.In some embodiments, the spacers 1132 are part of the MLA 1130, whereas in other embodiments, the spacers 1132 are provided as a separate component, for example, as an annular structure with a rectangular top view. In some embodiments, the spacers 1132 can be manufactured during the fabrication of the MLA 1130, for example, by omitting a border around the microlenses after etching the microlenses. Although a one-to-one representation in . Fig. As shown in Figure 11, this is not necessary and other image formats can be used.

[0035] Fig. Figure 12 is a simplified top-down diagram showing a silicon photonics substrate, several optical input fibers, and a high-density optical coupler according to an embodiment of the present invention. As shown in Fig. As shown in Figure 12, the system 1200 comprises two sets of optical input fibers, namely a first set of fibers 1210 and a second set of fibers 1215, both of which are optically coupled to the high-density optical coupler 1220. In some embodiments, each of the fibers in the first set of fibers 1210 and in the second set of fibers 1215 is laser-welded to a specific location on the high-density optical coupler 1220.

[0036] The high-density optical coupler 1220 can be a glass optical element or a silicon optical element, depending on the application. Several mode-field adapters (MFAs) are integrated into the high-density optical coupler 1220. As a result, light transmitted and input via an optical fiber, for example, optical fiber 1211, is fed into the mode-field adapter (MFA) 1221 and passes through the waveguide 1223. Similarly, light from other optical input fibers is fed into other MFAs before passing through other waveguides. As shown in Fig. As shown in Figure 12, the waveguides present in the high-density optical coupler 1220 can be designed such that an array of waveguides is provided at the output surface 1225 of the high-density optical coupler 1220. The array of waveguides at the output surface 1225 of the high-density optical coupler 1220 is optically coupled to a corresponding array of waveguides 1232 present at the silicon photonic device 1230.

[0037] Thus, in the Fig. In the illustrated embodiment 12, edge coupling is used in the silicon photonics device 1230, instead of surface coupling as discussed in the other embodiments. Because the optical fiber mode is converted to a waveguide mode away from the silicon photonics device, the usable area of ​​the silicon photonics device can be used more efficiently, as is appropriate for the small size of the silicon photonics device waveguide. It should be noted that the scaling of the system 1200 generally depends only on the silicon photonics device waveguide density, not on the diameter of the optical input fibers. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0038] Fig. Figure 5 is a simplified schematic diagram of a laser communication terminal with a fill factor correction plate according to an embodiment of the present invention. The diagram shown in Figure 5 is a simplified schematic diagram of a laser communication terminal with a fill factor correction plate according to an embodiment of the present invention. Fig. The 500 laser communication terminal shown has the following features: Fig. The laser communication terminal shown in 4A has 400 elements in common, and those relating to Fig. The description provided in section 4A is to be appropriately displayed. Fig. 5 applicable. In Fig. 5 The laser communication terminal 500 has a fill factor correction plate 510 which is optically located below the microlens array, i.e., in Fig. The fill factor correction plate 510 is located to the right of the microlens array. It improves the beam quality in the far field of the output beam 550 emitted by the laser communication terminal by converting multiple beamlets into a single beam during transmission. When the laser communication terminal 500 is operating in receive mode, it increases the coupling of the received beam into the microlens array by converting a single received beam into multiple beamlets, each directed towards one of the microlens elements.

[0039] Fig. Figure 6A is a simplified schematic diagram of a microlens array 600 according to an embodiment of the present invention. As shown, the microlens array 600 can comprise multiple lenslets 602, also referred to as a microlens or microlens element. A microlens element can be a small lens, generally with a diameter of less than one millimeter and down to 10 µm. Each of the lenslets 602 can be a single microlens with a planar surface and a convex (e.g., spherical) surface for refraction. In some cases, the lenslets 602 can be or include multiple layers of optical material to achieve desired optical properties. In some embodiments, the microlens array 600 can be formed as a one-dimensional or two-dimensional array of lenslets 602 on a supporting substrate.The Lenslets 602 can be used to focus and concentrate light from one or more optical fibers.

[0040] How more precisely in relation to Fig. 7A and Fig. As discussed in Figure 7B, multiple optical fibers can be bonded to the microlens array 600 at a microlens interface 605, e.g., by laser welding. A variety of bonding techniques can be used to align the optical fibers with the lenslets of the microlens array.

[0041] Fig. Figure 6B is a simplified schematic diagram of the alignment of an optical fiber with a lenslet in a microlens array according to an embodiment of the present invention. As shown in Fig. Figure 6B shows an opening plate 630 with multiple openings 632 adjacent to the one in Fig. Figure 6A illustrates the arrangement of microlens arrays. In some embodiments, the microlens array can be part of the aperture plate 630. In other embodiments, the aperture plate 630 can be aligned with the microlens array such that each of the apertures 632 is aligned with a lenslet of the microlens array. The distance between the apertures 632 of the aperture plate 630 can be equal to the distance between the lenslets 602 of the microlens array 600. In one example, the apertures 632 are produced using lithographic techniques.

[0042] To align the optical fiber 640 with a lenslet, the optical fiber 640 can be inserted into one of the openings 632. Because the opening is aligned with a lenslet, inserting the optical fiber 640 into one of the openings 632 is used to align the optical fiber 640 with the lenslet. Laser welding can then be performed to connect the optical fiber 640 to the corresponding lenslet.

[0043] Although some embodiments that are in Fig. The opening plate illustrated in 6B can be used, but this is not required by the present invention, and other bonding techniques can be used depending on their suitability for the particular application.

[0044] Fig. Figure 7A is a simplified schematic diagram showing the alignment and laser welding of optical fibers with a microlens array according to an embodiment of the present invention. Referring to Fig. 7A multiple optical fibers 710a - 710e with lenslets 712a - 712e are aligned and laser-welded to the microlens array 705. Although only five optical fibers and five lenslets are used in Fig. As shown in Figure 7A, it will be acknowledged that this number is merely exemplary and that other numbers of optical fibers and lenslets may be used in embodiments of the present invention.

[0045] In the embodiment shown, each of the lenslets 712a - 712e of the microlens array 705 is aligned with one of the multiple optical fibers 710a - 710e. For example, lenslet 712a can be aligned with optical fiber 710a, lenslet 712b can be aligned with optical fiber 710b, lenslet 712c can be aligned with optical fiber 710c, lenslet 712d can be aligned with optical fiber 710d, and lenslet 712e can be aligned with optical fiber 710e.

[0046] In some embodiments, a gold fiber can be used to align each of the Lenslets 712a–712e. For example, the gold optical fiber can be used to align each of the Lenslets 712a–712e by means of a microlens array alignment system. Once each of the Lenslets 712a–712e is in an alignment position, based on the alignment threshold, the gold optical fiber can then be removed from the system and replaced by one of the multiple optical fibers 710a–710e for each of the corresponding Lenslets 712a–712e. The optical fiber can then be secured to the microlens array, for example, by laser welding. Once an optical fiber has been secured to the microlens array, the microlens array can be repositioned, and the gold optical fiber can be used to align the next microlens.Thus, the process can be continued for each of the multiple optical fibers 710a - 710e. It should be understood that, using the systems and techniques employed herein, any number of multiple optical fibers 710a - 710e and any number of lenslets 712a - 712e can be aligned and / or secured.

[0047] As in Fig. As illustrated in Figure 7A, each of the optical fibers is aligned with a corresponding lenslet such that the output beams 720, including collimated outputs from each of the lenslets, are parallel to each other. In other, in Fig. In the embodiments illustrated in Figure 7B, the collimated outputs are characterized by finite angular differences between them, which allows for an increase in the acceptance angle of the received beam at the expense of optical efficiency for light received on the optical axis. As in relation to Fig. As described in Figure 7B, the microlens array comprises a central region and a peripheral (circumferential) region surrounding the central region. In the peripheral region, the optical fibers are connected to corresponding microlens elements at locations further away from the center of the microlens array than corresponding locations of the corresponding microlenses in the central region.

[0048] Fig. Figure 7B is a simplified schematic diagram showing the alignment of an optical fiber with a microlens array in a variable-angle implementation according to an embodiment of the present invention. As shown in Fig. Figure 7B illustrates that multiple optical fibers 720a–720e are aligned with the lenslets 722a–722e and laser-welded to the microlens array 715. In contrast to the illustration in Fig. In the illustrated embodiment 7A, only lenslet 722c is aligned with optical fiber 720c. The other four lenslets of the microlens array are intentionally misaligned with respect to their respective optical fibers.

[0049] In the Fig. In the illustrated embodiment 7B, the optical fibers are arranged near the perimeter of the microlens array, closer to the center of the microlens array than the corresponding microlens element that forms the interface to the optical fiber. As shown in Fig. As illustrated in Figure 7B, the optical fibers (namely optical fibers 720a and 720b) ​​near the top of the microlens array 715 are connected to the corresponding microlens elements (namely lenslets 722a and 722b) at interfaces located above the height of the microlens element. Consequently, light 724a emitted from the uppermost lenslet 722a travels at an upward angle, and light 724e emitted from the lowermost lenslet 722e travels at a downward angle. Similarly, light 724b emitted from the second lenslet 722b travels at an upward angle, and light 724d emitted from the fourth lenslet 722d travels at a downward angle. Light 724c emitted from the middle lenslet 722c travels without any angular deviation.

[0050] Thus, the receiving angle of a received beam is increased at the cost of optical efficiency for light received on the optical axis. Therefore, embodiments of the present invention provide systems in which the receiving angle of the microlens system can be predetermined and adjusted based on the offset between the centers of the optical fibers and that of the corresponding microlens element to which the optical fiber is attached.

[0051] Although in Fig. 7A and Fig. Figure 7B illustrates five optical fibers, and it will be apparent that embodiments of the present invention will generally employ a two-dimensional array of optical fibers arranged both in and into the plane of the drawing. The optical fibers are, for example, optically bonded, fused, or welded (e.g., laser-welded) to a microlens array, and the component formed by the optical fibers and the microlens array can be referred to as a fiber-clad microlens array. In these two-dimensional implementations, the microlens array can be described as having a central region and a peripheral region surrounding the central region.The optical fibers can be connected to corresponding microlens elements in the peripheral region of the microlens array at locations further from the center of the array than corresponding locations of the microlens elements in the central region. Someone with a basic understanding of the subject will recognize many variations, modifications, and alternatives.

[0052] In some embodiments, the microlenses in the microlens array can be identical. In other embodiments, each microlens can have unique optical parameters, including size, focal length, asphericity, and the like. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0053] Fig. Figure 8 is a simplified schematic diagram of a laser communication terminal according to an alternative embodiment of the present invention. The Fig. 8 illustrated laser communication terminal 800 features the in Fig. 4A illustrated laser communication terminal 400 common elements, and those relating to Fig. The description provided in section 4A is to be appropriately displayed. Fig. 8 applicable. In Fig. Figure 8 incorporates the laser communication terminal 800, a PIC 820, and a controller 822, which includes an integrated array of detectors. Thus, in the Fig. In the illustrated embodiment 8, the transmitted light (i.e., output beam 850) is emitted from the laser communication terminal 800, and the returning light (i.e., the returning beam 855) coming from the microlens array 432 to the PIC 820 is received by an array of detectors (not shown) on the PIC 820, instead of being routed back through the fanout array to an on-chip or off-chip single detector, e.g., the one shown in Fig. 4A illustrated detector 416 to be transferred.

[0054] Furthermore, in other embodiments, the laser source 410 can be integrated within the PIC, enabling the PIC to implement both light generation for transmitting optical signals and / or light detection for receiving optical signals. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0055] Fig. Figure 9 is a simplified flowchart showing a method for performing inter-satellite communication according to an embodiment of the present invention. The method 900 includes generating a laser signal at a first satellite (910) and transmitting the laser signal to a photonic integrated circuit (PIC) (912). In some embodiments, the laser signal is generated by a laser transmitter, which is a single-mode laser, and is transmitted to the PIC by means of a single-mode fiber.

[0056] The method also includes generating multiple spatially coherent laser beams (914), coupling each of the multiple spatially coherent laser beams into one of several first optical fibers (916), forming multiple coherent laser beams (918), and forming a single spatially coherent laser beam (920). Thus, the multiple coherent laser beams output by the PIC are fed into the optical fibers that constitute the multiple first optical fibers. Each of the optical fibers from the multiple first optical fibers is bonded to a microlens in a microlens array. In some embodiments, the optical fibers are bonded to the microlens by laser welding.Because each of the microlenses in the microlens array collimates one of the several coherent laser beams, each passing through a first optical fiber, a spatially coherent laser beam is produced with an aperture limited by the lateral dimensions of the microlens array, and which is suitable for inter-satellite communication. The method also involves transmitting the spatially coherent laser beam to a second satellite (922).

[0057] Method 900 additionally includes receiving the spatially coherent laser beam at the second satellite (924) and coupling the spatially coherent laser beam into several second optical fibers (926). As illustrated here, the spatially coherent laser beam can be received at a microlens array of a second laser communication terminal on the second satellite, which may be identical to the first laser communication terminal of the first satellite, and can be coupled into the several second optical fibers arranged in an array configuration. The light emitted by each of the several second optical fibers is transmitted to the PIC, which is used to combine the light emitted by the several second optical fibers (928) and to form a received laser signal (930).The received laser signal is transmitted to a detector (932) to complete the intersatellite communication process.

[0058] It should be noted that, although Fig. Section 9 provides a method for transmitting data from a first satellite to a second stellite; the same system for executing the method can also be used to transmit data from the second satellite back to the first stellite in order to implement bidirectional communication. Someone with normal technical knowledge will recognize many variations, modifications, and alternatives.

[0059] It should be acknowledged that the specific, in Fig. The nine illustrated steps provide a particular method for performing intersatellite communication according to one embodiment of the present invention. Other sequences of steps can also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps outlined above in a different order. Furthermore, the individual steps in Fig. The nine illustrated steps contain several sub-steps that can be performed in various orders depending on their suitability for the individual step. Furthermore, additional steps can be added or omitted depending on the specific application. Someone with average technical knowledge will recognize many variations, modifications, and alternatives.

[0060] Several examples of the present revelation are provided below. As used below, a reference to a series of examples is to be understood as a reference to each of these examples as a disjunction (e.g., “Examples 1-4” is to be understood as “Example 1, 2, 3, or 4”).

[0061] Example 1 is a laser communication terminal comprising: a laser; a receiver; a photonic integrated circuit (PIC) optically coupled to the laser and the receiver; multiple optical fibers, each of the multiple optical fibers being optically coupled to the PIC; and a microlens array, each of the multiple optical fibers being attached to the microlens array.

[0062] Example 2 is the laser communication terminal according to Example 1, wherein the laser comprises a single-mode laser.

[0063] Example 3 is the laser communication terminal according to Example 1-2, wherein the microlens array includes several microlens elements and each of the several optical fibers is attached to one of the several microlens elements.

[0064] Example 4 is the laser communication terminal according to Example 1-3, further comprising a fill factor correction plate.

[0065] Example 5 is the laser communication terminal according to Example 1-4, wherein the fill factor correction plate is arranged adjacent to the microlens array.

[0066] Example 6 is the laser communication terminal according to Example 1-5, wherein each of the multiple optical fibers is attached to a microlens interface on the microlens array.

[0067] Example 7 is the laser communication terminal according to Example 1-6, wherein the microlens interface is free of epoxy.

[0068] Example 8 is the laser communication terminal according to Example 1-7, wherein: the PIC comprises multiple waveguides and multiple phase matching elements; and each of the multiple waveguides is optically coupled to a corresponding phase matching element of the multiple phase matching elements.

[0069] Example 9 is the laser communication terminal according to Example 1-8, wherein each of the optical fibers is attached to the microlens array by means of laser welding.

[0070] Example 10 is the laser communication terminal according to Example 1-9, wherein: the microlens array comprises a central region and a circumferential region encompassing the central region; and one or more optical fibers with corresponding microlens elements in the circumferential region are connected at locations further away from the center of the microlens array than corresponding locations of the corresponding microlens elements.

[0071] Example 11 is a method for performing inter-satellite communication, comprising: generating a laser signal at a first satellite; transmitting the laser signal to a photonic integrated circuit (PIC); generating multiple spatially coherent laser beams; coupling each of the multiple spatially coherent laser beams into one optical fiber of multiple first optical fibers; forming multiple coherent laser beams; forming a spatially coherent laser beam using the multiple coherent laser beams; transmitting the spatially coherent laser beam to a second satellite; receiving the spatially coherent laser beam at the second satellite; coupling the spatially coherent laser beam into multiple second optical fibers; forming a received laser signal; and transmitting the received laser signal to a detector.

[0072] Example 12 is the method of Example 11, wherein each of the several coherent laser beams is collimated.

[0073] Example 13 is the method of Example 11-12, wherein the formation of several coherent laser beams comprises: splitting the laser signal into several input signals; applying a phase match to each of the several input signals to produce several phase-matched input signals; and coupling each of the several phase-matched input signals into one of the several first optical fibers of the several first optical fibers.

[0074] Example 14 is the method of Example 11-13, wherein forming a spatially coherent laser beam comprises collimating each of the several spatially coherent laser beams by means of a microlens of a microlens array.

[0075] Example 15 is the method of Example 11-14, wherein the laser signal comprises a single-mode laser beam.

[0076] Example 16 is the method of Example 11-15, wherein each of the multiple first optical fibers comprises a single-mode optical fiber.

[0077] Example 17 is the method of Example 11-16, wherein receiving the spatially coherent laser beam includes coupling the spatially coherent laser beam into a microlens array on the second satellite.

[0078] Example 18 is the method of Example 11-17, wherein combining light emitted from the multiple second optical fibers involves the use of combiners in a second PIC on the second satellite.

[0079] Example 19 is the method of Example 11-18, wherein combining light emitted from the multiple second optical fibers involves the use of combiners in a second PIC on the second satellite.

[0080] Example 20 is the procedure of Example 11-19, wherein the formation of the received laser signal includes the removal of optical degradation by means of phase-matching elements on the second satellite.

[0081] Example 21 is the procedure of Example 11-20, further comprising: operating several phase-matching elements in the PIC; and aligning the spatially coherent laser beam.

[0082] Example 22 is the method of Example 11-21, further comprising: operating several phase-matching elements in the PIC; and modifying a shape of the spatially coherent laser beam.

[0083] In summary, the present patent application discloses a laser communication terminal comprising a laser, a receiver, and a photonic integrated circuit (PIC) optically coupled to the laser and the receiver. The laser communication terminal may also include multiple optical fibers. Each of the multiple optical fibers may be optically coupled to the PIC. Each of the multiple optical fibers may be optically coupled to a microlens array. Each of the multiple optical fibers may be attached to the microlens array. The PIC may include multiple waveguides and multiple phase-matching elements. Furthermore, each of the multiple waveguides may be optically coupled to a corresponding phase-matching element of the multiple phase-matching elements.

[0084] The technology described and claimed herein is not limited in scope to the particular preferred embodiments disclosed herein, since these embodiments are intended as illustrations and not as limitations of any aspect of the technology. Any equivalent embodiment is intended to fall within the scope of this technology. Indeed, those skilled in the art will be aware of various modifications to the technology in addition to those shown and described herein, based on the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 6651,150

[0001] US 19 / 076,838

[0024]

Claims

[1] Laser communication terminal, comprising: a laser; a recipient; a photonic integrated circuit (PIC) optically coupled to the laser and the receiver; multiple optical fibers, each of which is optically coupled to the PIC; and a microlens array, wherein each of the multiple optical fibers is attached to the microlens array. [2] Laser communication terminal device according to claim 1, wherein the laser comprises a single-mode laser. [3] Laser communication terminal according to claim 1 or 2, wherein the microlens array includes several microlens elements and each of the several optical fibers is attached to one of the several microlens elements. [4] Laser communication terminal device according to one of claims 1 to 3, further comprising a fill factor correction plate. [5] Laser communication terminal according to claim 4, wherein the fill factor correction plate is arranged adjacent to the microlens array. [6] Laser communication terminal device according to one of claims 1 to 5, wherein each of the multiple optical fibers is attached to a microlens interface on the microlens array. [7] Laser communication terminal according to claim 6, wherein the microlens interface is free of epoxy. [8] Laser communication terminal device according to any one of claims 1 to 7, wherein: The PIC comprises multiple waveguides and multiple phase-matching elements; and Each of the multiple waveguides is optically coupled to a corresponding phase matching element of the multiple phase matching elements. [9] Laser communication terminal device according to any one of claims 1 to 8, wherein each of the optical fibers is attached to the microlens array by laser welding. [10] Laser communication terminal device according to any one of claims 1 to 8, wherein: the microlens array comprises a central region and a circumferential region surrounding the central region; and one or more optical fibers with corresponding microlens elements in the circumferential region are connected at locations further away from the center of the microlens array than corresponding locations of the corresponding microlens elements. [11] Method for carrying out inter-satellite communication, the method comprising: Generating a laser signal at a first satellite; Transmitting the laser signal to a photonic integrated circuit, PIC; Generating multiple spatially coherent laser beams; Coupling each of the several spatially coherent laser beams into one optical fiber of several first optical fibers; Formation of several coherent laser beams; Forming a spatially coherent laser beam using several mutually coherent laser beams; Transferring the spatially coherent laser beam to a second satellite; Receiving the spatially coherent laser beam at the second satellite; Coupling the spatially coherent laser beam into several second optical fibers; Forming a received laser signal; and Transmitting the received laser signal to a detector. [12] Method according to claim 11, wherein each of the several coherent laser beams is collimated. [13] Method according to claim 11 or 12, comprising forming several coherent laser beams: Splitting the laser signal into multiple input signals; Applying a phase adjustment to each of the multiple input signals to produce multiple phase-matched input signals; and Coupling each of the multiple phase-matched input signals into one of the multiple first optical fibers. [14] Method according to any one of claims 11 to 13, wherein forming a spatially coherent laser beam comprises collimating each of the several spatially coherent laser beams by means of a microlens of a microlens array. [15] Method according to any one of claims 11 to 14, wherein the laser signal comprises a single-mode laser beam. [16] Method according to any one of claims 1 to 15, wherein each of the multiple first optical fibers comprises a single-mode optical fiber. [17] Method according to any one of claims 1 to 16, wherein receiving the spatially coherent laser beam comprises coupling the spatially coherent laser beam into a microlens array on the second satellite. [18] Method according to any one of claims 1 to 17, wherein the combining of light emitted from the multiple second optical fibers comprises the use of combiners in a second PIC on the second satellite. [19] Method according to any one of claims 1 to 18, wherein the formation of the received laser signal comprises the removal of intersymbol interference by means of phase matching elements on the second satellite. [20] Method according to any one of claims 1 to 19, wherein the formation of the received laser signal comprises the removal of optical deterioration by means of phase matching elements on the second satellite. [21] Method according to any one of claims 1 to 20, further comprising: Operating multiple phase-matching elements in the PIC; and Aligning the spatially coherent laser beam. [22] The method of claim 21, further comprising: Operating multiple phase-matching elements in the PIC; and Modifying the shape of a spatially coherent laser beam.

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