Hybrid optical phased array phase modulation

Abstract

To provide hybrid optical phased array phase modulation.SOLUTION: Aspects of the disclosure provide an optical communication terminal which may include an optical phased array (OPA). The OPA may include: a plurality of emitters; and a set of phase shifters which may include a first phase shifter and a second phase shifter. The first and second phase shifters may be arranged such that an incoming signal is modulated by the first phase shifter with a first update rate and a first tuning range and thereafter further modulated by the second phase shifter with a second update rate and a second tuning range. The first update rate may be different from the second update rate, and the first tuning range may be different from the second tuning range. The first phase shifter may be associated with one emitter of the plurality of emitters, and the second phase shifter may be associated with two emitters of the plurality of emitters.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 609,398, filed on December 13, 2023, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] Background

[0002] Wireless optical communication enables high - throughput and long - distance communication due in part to the high gain provided by the narrow angular width of the transmitted beam. However, a narrow beam also requires accurate and active pointing to maintain alignment with the aperture of the communication terminal at the remote end. This pointing can be achieved by a small mirror (e.g., a MEMS or voice - coil - based fast - steering mirror mechanism) that actuates to steer the beam. In other implementations, solid - state steering of the beam without using a moving part is used, which provides cost, lifetime, and performance advantages. An optical phased array (OPA) is an important technical component that adds the advantages of adaptive optics, point - to - multi - point support, and mesh network topology. Each active element in an OPA requires solid - state phase - shifting capabilities.

Summary of the Invention

Means for Solving the Problems

[0003] Brief Summary

[0003] Aspects of the present disclosure provide an optical communication terminal. The optical communication terminal includes an optical phased array (OPA). The OPA includes a plurality of emitters and a set of phase shifters including a first phase shifter and a second phase shifter, wherein the first phase shifter and the second phase shifter are arranged such that an incident signal is modulated by the first phase shifter at a first update rate and within a first tuning range, and then further modulated by the second phase shifter at a second update rate and within a second tuning range, the first update rate being different from the second update rate, and the first tuning range being different from the second tuning range, the set of phase shifters, and the first phase shifter is associated with at least one emitter of the plurality of emitters, and the second phase shifter is associated with at least two emitters of the plurality of emitters.

[0004]

[0004] In one example, the first phase shifter and the second phase shifter are arranged such that an output signal is modulated by the second phase shifter at a second update rate and within a second tuning range, and then further modulated by the first phase shifter at a first update rate and within a first tuning range.

[0005]

[0005] In another example, the second phase shifter is associated with at least four emitters of the plurality of emitters.

[0006]

[0006] In a further example, the set of phase shifters further includes a third phase shifter having a third update rate and a third tuning range. Additionally, the second tuning range may be the same as the third tuning range. Additionally or alternatively, the second update rate is the same as the third update rate. Additionally or alternatively, the first phase shifter, the second phase shifter, and the third phase shifter are arranged such that the emitted signal can be modulated by the third phase shifter at the third update rate and the third tuning range, and then further modulated by the second phase shifter at the second update rate and the second tuning range, and then further modulated by the first phase shifter at the first update rate and the first tuning range. Additionally or alternatively, the first phase shifter, the second phase shifter, and the third phase shifter are arranged such that the incident signal can be modulated by the first phase shifter at the first update rate and the first tuning range, and then further modulated by the second phase shifter at the second update rate and the second tuning range, and then further modulated by the third phase shifter at the third update rate and the third tuning range.

[0007]

[0007] In another example, the set of phase shifters is a plurality of sets of phase shifters each including a first phase shifter associated with each of at least one of the second phase shifters associated with each of at least two of the plurality of emitters. Additionally, the first phase shifter of the plurality of sets of phase shifters may be disposed in the first layer, and the second phase shifter of the plurality of sets of phase shifters may be disposed in the second layer.

[0008]

[0008] In a further example, the first tuning range is greater than 2π and the first update rate is on the order of 1 kHz.

[0009]

[0009] In a further example, the second tuning range is less than π and the second update rate is on the order of 10 kHz to 100 kHz.

[0010]

[0010] In another example, the first phase shifter is a thermo-optic phase shifter.

[0011]

[0011] In a further example, the second phase shifter is a carrier phase shifter.

[0012]

[0012] Another aspect of the present disclosure provides a method of modulating a signal in an optical phased array (OPA) of an optical communication terminal. The method includes modulating the signal at a first update rate and a first tuning range in a first phase shifter of the OPA, and modulating the signal at a second update rate and a second tuning range in a second phase shifter of the OPA, wherein the first update rate is different from the second update rate, and the first tuning range is different from the second tuning range, and the first phase shifter is associated with at least one emitter of a plurality of emitters, and the second phase shifter is associated with at least two emitters of the plurality of emitters.

[0013]

[0013] In one example, when the signal is an incident signal, the modulation in the first phase shifter of the OPA is performed before the modulation in the second phase shifter of the OPA.

[0014]

[0014] In another example, when the signal is an outgoing signal, the modulation in the second phase shifter of the OPA is performed before the modulation in the first phase shifter of the OPA.

[0015]

[0015] In a further example, the method further includes modulating the signal at a third update rate and a third tuning range in a third phase shifter of the OPA. Additionally, when the signal is an incident signal, the modulation in the third phase shifter may be performed following the modulation in the first and second phase shifters of the OPA. Additionally or alternatively, the second update rate may be the same as the third update rate.

Brief Description of the Drawings

[0016] Brief Description of the Drawings

Fig. 1

[0016] Block diagram 100 of a first communication terminal and a second communication terminal according to an aspect of the present disclosure.

Fig. 2

[0017] FIG. 200 is a diagram of an exemplary system architecture for a first communication device of FIG. 1, according to an aspect of the present disclosure.

Fig. 3

[0018] Shows features of an OPA architecture shown as an exemplary OPA chip, according to an aspect of the present disclosure.

Fig. 4

[0019] FIG. is a diagram of a network according to an aspect of the present disclosure.

Fig. 5

[0020] FIG. is a block diagram according to an aspect of the present disclosure.

Fig. 6

[0021] FIG. is a diagram according to an aspect of the present disclosure.

Fig. 7

[0022] FIG. is a diagram according to an aspect of the present disclosure.

Fig. 8A

[0023] FIG. is a block diagram according to an aspect of the present disclosure.

Fig. 8B

[0024] FIG. is a block diagram according to an aspect of the present disclosure.

Fig. 9A

[0025] FIG. is a block diagram according to an aspect of the present disclosure.

Fig. 9B

[0026] FIG. is a block diagram according to an aspect of the present disclosure.

Fig. 10

[0027] FIG. is a flowchart according to an aspect of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION SUMMARY

[0028] The present technology relates to an optical phased array (OPA) of a phase shifter of an optical communication terminal configured to utilize a hybrid phase modulation technique. The optical communication terminal may be configured for bidirectional communication. The OPA may be included in a photonic integrated circuit (PIC). The hybrid phase modulation technique may enable different modulations or tuning ranges and / or update rates of transmission (outgoing) signals and reception (incoming) signals (e.g., optical communication beams) in different phase shifters of the OPA. In some cases, different types of phase shifters may be used for different tuning ranges and / or update rates.

[0018]

[0029] Generally, the phase shifters of an OPA include the same type of phase shifters having the same update rate and tuning range. Such a technique may lack scalability and may require a complex, large, and expensive structure. For example, a phase shifter configured to cover a large tuning range tends to be large in size and tends to require a large set of auxiliary devices. As a result, the space for additional components may be significantly limited.

[0019]

[0030] To address this, as described above, an OPA that utilizes a hybrid phase modulation technique that provides phase shifters with different tuning ranges and / or update rates can be used. In this regard, the OPA can leverage the advantages of such techniques while minimizing the disadvantages of different tuning techniques. For example, thermal tuning has the disadvantages of high power loss and slow update speed, and carrier-based tuning has the disadvantages of tuning-dependent optical loss and low tuning efficiency. In this regard, thermal tuning may be used in combination with carrier-based tuning. Another major advantage of this architecture is the possibility of sharing phase shifters with different tuning techniques among multiple antennas or emitters. Sharing of phase shifters can reduce the complexity of the system and free up free space on the PIC for other components, thereby improving scalability.

[0020] Exemplary System

[0031] FIG. 1 is a block diagram 100 of a first communication terminal configured to form one or more links with a second communication terminal as part of a system such as, for example, a free space optical communication (FSOC) system. FIG. 2 is a drawing 200 of an exemplary communication terminal such as the first communication terminal of FIG. 1. For example, the first communication terminal 102 includes one or more processors 104, a memory 106, a transceiver photonic integrated chip 112, and an optical phased array (OPA) architecture 114. In some implementations, the first communication terminal 102 may include two or more transceiver chips and / or two or more OPA architectures (e.g., two or more OPA chips).

[0021]

[0032] The one or more processors 104 may be any conventional processor such as a commercially available CPU. Alternatively, the one or more processors may be a dedicated device such as an application specific integrated circuit (ASIC), or another hardware-based processor such as a field programmable gate array (FPGA). FIG. 1 illustrates the one or more processors 104 and the memory 106 as being within functionally the same block, such as the digital signal processing modem 202 shown in FIG. 2, but the one or more processors 104 and the memory 106 may actually be stored within the same physical housing, like both the modem 202 and a separate processing unit 203, or may include multiple processors and memories that may or may not be stored therein. Accordingly, references to a processor or computer are to be understood to include references to a group of processors or computers or memories that may or may not operate in parallel.

[0022]

[0033] Memory 106 can store information accessible by one or more processors 104, including data 108 and instructions 110 that can be executed by one or more processors 104. The memory can be any type capable of storing information accessible by a processor, including computer-readable media such as hard drives, memory cards, ROM, RAM, DVDs, or other optical discs, as well as other writable and read-only memories. The system and method may include the above different combinations, whereby different portions of data 108 and instructions 110 are stored on different types of media. The memory of each communication terminal, such as memory 106, may store calibration information such as one or more offsets determined to track signals.

[0023]

[0034] Data 108 may be retrieved, stored, or modified by one or more processors 104 according to instructions 110. For example, although not limited by a particular data structure, data 108 may be stored in computer registers, relational databases as tables with multiple different fields and records, XML documents, or flat files. Data 108 may also be formatted in any computer-readable format, such as, but not limited to, binary or Unicode. As a further example only, image data may include a bitmap, which is a grid of pixels stored according to a format that is compressed or uncompressed, reversible (e.g., BMP) or irreversible (e.g., JPEG), and bitmap or vector-based (e.g., SVG), as well as computer instructions for drawing graphics. Data 108 can include any information sufficient to identify related information, such as numbers, descriptive text, claimable codes, references to data stored in other areas of the same memory or different memories (including other network locations), or information used by functions to calculate related data.

[0024]

[0035] Command 110 may be any set of instructions that are directly (such as machine code) or indirectly (such as a script) executed by one or more processors 104. For example, command 110 may be stored as computer code on a computer-readable medium. In this regard, the terms "instruction" and "program" may be used synonymously herein. Command 110 may be stored in object code form for direct processing by one or more processors 104, or may be stored in any other computer language including scripts or groups of independent source code modules that are interpreted on demand or pre-compiled. The functions, methods, and routines of command 110 will be described in more detail below.

[0025]

[0036] One or more processors 104 may communicate with transceiver chip 112. As shown in FIG. 2, one or more processors within modem 202 may communicate with transceiver chip 112 configured to receive and process incident optical signals and to transmit optical signals. Transceiver chip 112 may include one or more transmitter components and one or more receiver components. Thus, one or more processors 104 may be configured to transmit data within a signal via the transmitter components and may also be configured to receive communications and data within the signal via the receiver components. The received signal may be processed by one or more processors 104 to extract the communications and data.

[0026]

[0037] The transmitter component may minimally include a light source such as the seed laser 116. Other transmitter components may include an amplifier such as the high-power semiconductor optical amplifier 204. In some implementations, the amplifier is on a separate photonics chip. The seed laser 116 may be a distributed feedback laser (DFB), a laser diode, a fiber laser, or a solid-state laser. The optical output or optical signal of the seed laser 116 can be controlled by a current or electrical signal directly applied to the seed laser from, for example, a modulator that modulates the received electrical signal. The light transmitted from the seed laser 116 is received by the OPA architecture 114.

[0027]

[0038] The receiver component may minimally include a sensor 118 such as a photodiode. The sensor can convert the received signal (e.g., light or an optical communication beam) into an electrical signal that can be processed by one or more processors. Other receiver components may include an attenuator such as the variable optical attenuator 206, an amplifier such as the semiconductor optical amplifier 208, or a filter.

[0028]

[0039] One or more processors 104 may communicate with an OPA architecture 114. The OPA architecture may include a microlens array, emitters (e.g., antennas, general couplers, coupling devices, etc.) associated with each microlens in the array, a plurality of phase shifters, and waveguides that connect components within the OPA. The OPA architecture may be disposed on an OPA chip that is a single chip. The waveguides gradually merge between a plurality of emitters and edge couplers that connect to other transmitter components and / or receiver components. In this regard, the waveguides can direct light between a photodetector or fiber, phase shifters, waveguide combiners, emitters, and any additional components within the OPA that are external to the OPA architecture. In particular, the waveguide configuration can couple two waveguides at each stage, which means that the number of waveguides decreases by half at each successive stage closer to the edge coupler. The coupling points may be nodes, and combiners may be present at each node. The combiners may be 2×2 multimode interference (MMI) or directional couplers.

[0029]

[0040] The OPA architecture 114 can receive light from a transmitter component and output the light as a coherent communication beam received by a remote communication terminal such as a second communication terminal 122. The OPA architecture 114 can also receive light from free space such as a communication beam from the second communication terminal 122 and provide such received light to a receiver component. The OPA architecture can provide the photonic processing necessary to couple an incident optical communication beam to a single-mode waveguide that directs the beam to the transceiver chip 112. In some implementations, the OPA architecture can also generate an angle of arrival estimate and provide it to one or more processors 104 (such as those within the processing unit 203).

[0030]

[0041] The first communication terminal 102 may include additional components for supporting the functions of a communication terminal. For example, the first communication terminal may include one or more lenses and / or mirrors that form a telescope. The telescope can receive collimated light and output collimated light. The telescope may include an objective lens portion, an eyepiece lens portion, and a relay portion. As shown in FIG. 2, the first communication terminal may include a telescope including an objective lens 210, an eyepiece lens 212, and an aperture 214 (or opening) through which light can enter and exit the communication terminal. Although the objective lens 210 may be disposed within the aperture, the aperture 214 is depicted separately from the objective lens 210 for ease of display and understanding. The first communication terminal may include a circulator or wavelength splitter, such as a single-mode circulator 218, that routes incident signals (e.g., light) and outgoing signals (e.g., light) while maintaining these signals on at least partially separate paths. The first communication terminal may include one or more sensors 220 for detecting environmental characteristics and / or measurements of system components.

[0031]

[0042] The first communication terminal 102 may include one or more biasing means for controlling one or more phase shifters that may be part of the OPA architecture 114, and / or one or more steering mechanisms, such as an actuation / steering mirror (not shown), such as a fast / fine pointing mirror. In some examples, the actuation mirror may be a MEMS biaxial mirror, a biaxial voice coil mirror, or a piezoelectric biaxial mirror. One or more processors 104 (such as those within the processing unit 203) may be configured to receive and process signals from one or more sensors 220, the transceiver chip 112, and / or the OPA architecture 114, and to control one or more steering mechanisms to adjust the pointing direction and / or the wavefront shape. The first communication terminal also includes an optical fiber or waveguide that connects the optical components, thereby creating a path between the seed laser 116 and the OPA architecture 114 and a path between the OPA architecture 114 and the sensor 118.

[0032]

[0043] Returning to FIG. 1, the second communication terminal 122 can output a Tx signal as an optical communication beam 20b (e.g., light) pointed toward the first communication terminal 102, and the first communication terminal 102 receives the optical communication beam 20b (e.g., light) as a corresponding Rx signal. In this regard, the second communication terminal 122 includes one or more processors 124, a memory 126, a transceiver chip 132, and an OPA architecture 134. The one or more processors 124 may be the same as the one or more processors 104 described above.

[0033]

[0044] The memory 126 can store information accessible by one or more processors 124, including data 128 and instructions 130 that can be executed by the processor 124. The memory 126, the data 128, and the instructions 130 may be configured in the same manner as the memory 106, the data 108, and the instructions 110 described above. Further, the transceiver chip 132 and the OPA architecture 134 of the second communication terminal 122 may be the same as the transceiver chip 112 and the OPA architecture 114. The transceiver chip 132 may include both a transmission component and a reception component. The transmission component may include a light source such as a seed laser 136 configured in the same manner as the seed laser 116. Other transmission components may include an amplifier such as a high-power semiconductor optical amplifier. The reception component may include a sensor 138 configured in the same manner as the sensor 118. Other reception components may include an attenuator such as a variable optical attenuator, an amplifier such as a semiconductor optical amplifier, or a filter. The OPA architecture 134 may include an OPA chip including a microlens array, a plurality of emitters, and a plurality of phase shifters. Additional components for supporting the functions of the second communication terminal 122 similar to the above additional components may be included. The second communication terminal 122 may have a system architecture identical or similar to the system architecture shown in FIG. 2.

[0034]

[0045] Figure 3 shows the features of OPA architecture 114 shown as an exemplary OPA chip 300, including the display of a microlens array 310, a plurality of emitters 320, and a plurality of phase shifters 330. For clarity and ease of understanding, additional waveguides and other features are not depicted. Arrows 340, 342 represent the general directions of the Tx signal (transmitted optical communication beam) and the Rx signal (received optical communication beam) when passing through or moving through the OPA chip 300.

[0035]

[0046] The microlens array 310 may include a plurality of convex microlenses 311 - 315 that focus the Rx signal onto each of a plurality of emitters disposed at the focal points of the microlens array. In this regard, the dashed line 350 represents the focal plane of the microlenses 311 - 315 of the microlens array 310. The microlens array 310 may be arranged in a grid pattern with a consistent pitch or distance between adjacent lenses. In other examples, the microlens array 310 may have different arrangements with different numbers of rows and columns, different shapes, and / or different pitches (consistent or inconsistent) for different lenses.

[0036]

[0047] Each microlens of the microlens array may have a diameter and height in the range of several tens to several hundreds of micrometers. Further, each microlens of the microlens array may be manufactured by directly forming, printing, or etching a lens on the wafer of the OPA chip 300. Alternatively, the microlens array 310 may be formed as a separately fabricated microlens array. In this example, the microlens array 310 may be a rectangular or square plate of glass or silica with a length and width in the range of several millimeters (e.g., 10 mm or more or less) and a thickness of 0.2 mm or more or less. By integrating the microlens array within the OPA chip 300, it may be possible to reduce the size of the grating emitter and increase the space between the emitters. In this way, two-dimensional waveguide routing in the OPA architecture may better conform to a single-layer optical phased array. In other examples, instead of a physical microlens array, an array of diffractive optical elements (DOEs) may be used to reproduce the function of the microlens array.

[0037]

[0048] Each microlens of the microlens array may be associated with each of the plurality of emitters 320. For example, each microlens may have an emitter from which a Tx signal is received and to which an Rx signal is focused. As an example, the microlens 311 is associated with the emitter 321. Similarly, each of the microlenses 312 - 315 also has its respective emitter 322 - 325. In this regard, for a given pitch (i.e., the length of the edge of the microlens), the focal length of the microlens may be optimized for the best transmission and reception coupling to the underlying emitter. Thus, this arrangement may increase the effective fill factor of the Rx signal at each emitter while expanding the Tx signal received at the microlens from each emitter before the Tx signal leaves the OPA chip 300.

[0038]

[0049] The plurality of emitters 320 may be configured to convert radiation from the waveguide to free space and vice versa. The emitter may also generate a specific phase and intensity profile to further increase the effective fill factor of the Rx signal and improve the wavefront of the Tx signal. The phase and intensity profiles may be determined using inverse design or other techniques in a manner that takes into account how the transmitted signal changes as it propagates through and passes through the microlens array. The phase profile may differ from the flat profile of a conventional grating emitter, and the intensity profile may differ from the Gaussian intensity profile of a conventional grating emitter. However, in some implementations, the emitter may be a grating emitter with a Gaussian field profile.

[0039]

[0050] The phase shifter 330 may perform detection and measurement of the Rx signal and modify the Tx signal to optimally improve the signal strength, enabling the input wavefront to be coupled to a single waveguide or fiber. Each emitter may be associated with a phase shifter. As shown in FIG. 3, each emitter may be connected to its respective phase shifter. As an example, emitter 320 is associated with phase shifter 330. The Rx signals received by phase shifters 331 - 335 may be provided to a receiver component including sensor 118, and the Tx signals from phase shifters 331 - 335 may be provided to each of the plurality of emitters 320. The architecture of the plurality of phase shifters 330 may include at least one layer of phase shifters having at least one phase shifter connected to one of the plurality of emitters 320. In some examples, the phase shifter architecture may include multiple layers of phase shifters, and the phase shifters of the first layer may be connected in series with one or more phase shifters of the second layer.

[0040]

[0051] Communication link 22 can be formed between the first communication terminal 102 and the second communication terminal 122 when the transceivers of the first and second communication terminals are aligned. The alignment can be determined using optical communication beams 20a, 20b to determine when a line of sight is established between communication terminals 102 and 122. Using communication link 22, one or more processors 104 can transmit communication signals to the second communication terminal 122 via free space using optical communication beam 20a, and one or more processors 124 can transmit communication signals to the first communication terminal 102 via free space using optical communication beam 20b. The communication link 22 between the first communication terminal 102 and the second communication terminal 122 enables bidirectional transmission of data between the two devices. Specifically, the communication link 22 in these examples may be a free space optical communication (FSOC) link. In other implementations, one or more of the communication links 22 may be a radio frequency communication link or other type of communication link that can move through free space.

[0041]

[0052] As shown in FIG. 4, a plurality of communication terminals such as the first communication terminal 102 and the second communication terminal 122 may be configured to form a plurality of communication links (indicated by arrows) between the plurality of communication terminals, thereby forming a network 400. The network 400 may include client devices 410 and 412, a server device 414, and communication terminals 102, 122, 420, 422, and 424. Each of the client devices 410, 412, the server device 414, and the communication terminals 420, 422, and 424 may include one or more processors, memories, transceiver chips, and OPA architectures (e.g., OPA chips or chips) similar to those described above. Using transmitters and receivers, each communication terminal within the network 400 may form at least one communication link with another communication terminal, as indicated by the arrows. The communication links may be for optical frequencies, radio frequencies, other frequencies, or combinations of different frequency bands. In FIG. 4, a first communication terminal 102 having communication links with the client device 410 and the communication terminals 122, 420, and 422 is shown. A second communication terminal 122 having communication links with the communication terminals 102, 420, 422, and 424 is shown.

[0042]

[0053] Network 400 as shown in FIG. 4 is merely an example, and in some implementations, network 400 may include additional communication terminals or different communication terminals. Network 400 may be a terrestrial network where multiple communication terminals are on multiple terrestrial communication terminals. In other implementations, network 400 may be one or more high-altitude platforms (HAPs) such as balloons, small airships, or other airships, airplanes, unmanned aerial vehicles (UAVs), satellites, or any other type of mobile or stationary communication terminal, or may include other types of mobile or stationary communication terminals. In some implementations, network 400 may function as an access network for client devices such as mobile phones, laptop computers, desktop computers, wearable devices, or tablet computers. Network 400 may also be connected to a larger network such as the Internet and may be configured to provide client devices with access to resources stored on or provided through the larger computer network.

[0043]

[0054] As described above, different phase shifters of the OPA of the optical communication terminals (e.g., the first optical communication terminal 102, the second optical communication terminal 122) may modulate the transmitted (emitted) signal and the received (incident) signal at different update rates and / or different tuning ranges. The OPA may be included in a PIC having a plurality of features such as, for example, a microlens array, emitters associated with each microlens, a set of phase shifters for each microlens, and waveguides connecting components within the OPA architecture. The set of phase shifters may include different types of phase shifters.

[0044]

[0055] Figure 5 shows an example 500 in which each emitter 520 (e.g., an antenna, a general coupler, a coupling device, etc.) is associated with sets 541, 543, 545, 547 of phase shifters. Figure 5 shows sets 541, 543, 545, 547 of phase shifters. Each set 541, 543, 545, 547 of phase shifters includes a first phase shifter 532 (e.g., a high amplitude, low speed phase shifter) and a second phase shifter 534 (e.g., a low amplitude, high speed phase shifter). In such an example, when receiving a signal at emitter 520, the incident signal can be modulated by the first phase shifter 532, and then this signal can be further modulated by the second phase shifter 534. When transmitting a signal, the outgoing signal can be modulated by the second phase shifter 534. Then, this signal can be further modulated by the first phase shifter 532 before being transmitted by emitter 520.

[0045]

[0056] The first phase shifter 532 may be used for a larger scale phase modulation of the signal, and the second phase shifter 534 may be used for a smaller scale phase modulation of the signal. In this regard, the first phase shifter 532 may have a first phase synchronization range, and the second phase shifter 534 may have a second phase synchronization range. The first phase synchronization range may be larger than the second phase synchronization range. For example, the first synchronization range may be larger than 2π, the second synchronization range may be smaller than π, or significantly smaller than π. Further, the first phase shifter 532 may have a first update rate, and the second phase shifter 534 may have a second update rate. The first update rate may be smaller than the second update rate. For example, the first update rate may be on the order of 1 kHz, and the second update rate may be on the order of 10 - 100 kHz. In some cases, the first phase shifter 532 may be used to perform large scale steering correction of the signal, and the second phase shifter 534 may be used for noise or environmental variation correction strategies (e.g., dithering).

[0046]

[0057] In some cases, the first phase shifter 532 and / or the second phase shifter 534 may be a heater type phase shifter such as a thermo-optic phase shifter. The heater type phase shifter may be configured to modulate the frequency of a signal. The heater type phase shifter may include a heating element and a waveguide. The heating element may be configured to heat a portion of the waveguide so that the refractive index is modified. In this regard, the signal passing through the heater type phase shifter may be modulated. FIG. 6 shows some exemplary heater type phase shifters. In one example, as shown in example (a) of FIG. 6, the heater element 652a is disposed above the waveguide 650 or a portion thereof. In another example, as shown in example (b) of FIG. 6, the heater element 652b is located at the same level as the waveguide 650 or a portion thereof. In this regard, the heater element 652b may be adjacent to the waveguide 650 or a portion thereof. In a further example, the heater element 652c is embedded in the waveguide 652 or a portion thereof, as shown in example (c) of FIG. 6. In some cases, the heater element 652 may be made of a material such as metal, silicon. Further, in some cases, the material may be a doped material.

[0047]

[0058] In some cases, the first phase shifter 532 and / or the second phase shifter 534 may be a carrier phase shifter. The carrier phase shifter may be configured to modify the frequency and amplitude of a signal. FIG. 7 shows some exemplary carrier phase shifters. In one example, the carrier phase shifter may be a PN carrier depletion phase shifter operating in reverse bias, as shown in example (a) of FIG. 7. In another example, the carrier phase shifter may be a PIN carrier injection phase shifter operating in forward bias, as shown in example (b) of FIG. 7. Other junction geometries and doping profiles (vertical, S, U, lateral NPN, etc.) can also be considered for carrier-based modulation.

[0048]

[0059] In some cases, the phase shifters of a set of phase shifters associated with different emitters may partially overlap. In this regard, a single phase shifter may be associated with multiple emitters. FIG. 8A shows an example 800a of the arrangement of one second phase shifter for two emitters. In such an example, each first phase shifter 832a, 832b is associated with a single respective emitter 820a, 820b, and each second phase shifter 834 is associated with a pair of emitters 820a, 820b.

[0049]

[0060] FIG. 8B shows another example 800b of the arrangement of one second phase shifter for four emitters. In such an example, each first phase shifter 832a, 832b, 832c, 832d is associated with a single respective emitter 820a, 820b, 820c, 820d, and each second phase shifter 834 is associated with the four emitters 820a, 820b, 820c, 820d.

[0050]

[0061] In some cases, each emitter may further be associated with a third phase shifter. The third phase shifter may be the same type of phase shifter as the first or second phase shifter, and / or may have the same functions (e.g., update rate, number of frequencies within the tuning range, steering function, noise correction function, etc.) as the first or second phase shifter. In some examples, each emitter may be associated with a different third phase shifter. Alternatively, each third phase shifter may be associated with multiple emitters. FIG. 9A shows an example 900a in which the third phase shifter is associated with four emitters. In such an example, each first phase shifter 932a, 932b, 932a', 932b' is associated with a single respective emitter 920a, 920b, 920a', 920b', each second phase shifter 934, 934' is associated with each pair of emitters 920a, 920b and 920a', 920b', and the third phase shifter is associated with the four emitters 920a, 920b, 920a', 920b'.

[0051]

[0062] Figure 9B shows a further example 900b where a third phase shifter is associated with eight emitters. In such an example, each of the first phase shifters 932a, 932b, 932c, 932d, 932a’, 932b’, 932c’, 932d’ is associated with a single respective emitter 920a, 920b, 920c, 920d, 920a’, 920b’, 920c’, 920d’, each of the second phase shifters 934, 934’ is associated with four respective emitters 920a, 920b, 920c, 920d and 920a’, 920b’, 920c’, 920d’, and the third emitter is associated with the eight emitters 920a, 920b, 920c, 920d, 920a’, 920b’, 920c’, 920d’.

[0052]

[0063] For simplicity and to facilitate the presentation, only one third phase shifter is depicted in FIGS. 9A - 9B, but the OPA of the optical communication terminal may include one or more third phase shifters each associated with one or more of the plurality of emitters. Also, in some cases, each emitter may be associated with additional phase shifters (e.g., a fourth phase shifter, a fifth phase shifter,... an Nth phase shifter).

[0053]

[0064] In some cases, the phase shifters may be arranged in N layers. N may be the number of phase shifters associated with each emitter. In this regard, the first phase shifter may be arranged in the first layer, the second phase shifter may be arranged in the second layer, and the third phase shifter may be arranged in the third layer. FIGS. 5, 8A, 8B, 9A, and 9B show the first phase shifters 532, 832, 932, 932’ arranged in the first layer and the second phase shifters 534, 834, 934, 934’ arranged in the second layer. Further, FIGS. 9A and 9B show the third phase shifter 936 arranged in the third layer. In some cases, each layer may include a plurality of phase shifters.

[0054]

[0065] In some cases, each layer of the phase shifter may be configured to modulate a signal within a different phase synchronization range. An additional layer may enable a smaller phase synchronization range in each layer. A smaller phase synchronization range in each layer may enable more accurate signal modulation. In a first example, if the entire synchronization range is 2π and there are two layers, the first layer may have a synchronization range of 0 to π, and the second layer may have a synchronization range of π to 2π. In a second example, if the entire synchronization range is 2π and there are three layers, the first layer may have a synchronization range of 0 to π, the second layer may have a synchronization range of π to 1.5π, and the third layer may have a synchronization range of 1.5π to 2π. In this regard, in both examples, the entire synchronization range is 2π, but in the second example with three layers, since the synchronization ranges of the second and third layers are smaller, more accurate signal modulation may be enabled in the second and third layers. In some cases, the synchronization range of each layer may include a single frequency.

[0055]

[0066] One or more processors of the optical communication terminal (e.g., one or more processors 104, one or more processors 124) may be configured to drive the phase shifter of the OPA. In some cases, different phase shifters (e.g., the first phase shifters 532, 832, 932, 932', the second phase shifters 534, 834, 934, 934', the third phase shifter 936) may be driven by different processors among the one or more processors. In some cases, phase shifters having the same synchronization range and / or update rate may be driven by the same processor among the one or more processors. For example, each of the first, second, and third phase shifters may be driven by a different processor. In another example, if the phase shifter is arranged in N layers, each layer of the phase shifter may be driven by a different processor.

[0056] Method Example

[0067] As described above, the OPA of the optical communication terminal can be used in a hybrid phase modulation technique. In this regard, the optical communication terminal can be used in a method of modulating a signal transmitted or received in the OPA.

[0057]

[0068] FIG. 10 shows an exemplary method 1000 for modulating a signal transmitted or received in an OPA. At block 1010, the method includes modulating a signal at a first update rate and within a first tuning range in a first phase shifter of the OPA. At block 1020, the method further includes modulating the signal at a second update rate and within a second tuning range in a second phase shifter. The first update rate is different from the second update rate, and the first tuning range is different from the second tuning range. The first phase shifter is associated with one of a plurality of emitters, and the second phase shifter is associated with two of the plurality of emitters. In this regard, the incident (received) signal and the outgoing (transmitted) signal can be modulated by the first phase shifters 532, 832, 932, 932' and the second phase shifters 534, 834, 934, 934'. As described above, the first phase shifters 532, 832, 932, 932' may have a first phase tuning range, and the second phase shifters 534, 834, 934, 934' may have a second phase tuning range. The first phase tuning range may be larger than the second phase tuning range.

[0058]

[0069] Further, as described above, the first update rate may be smaller than the second update rate. For example, the first update rate may be on the order of 1 kHz, and the second update rate may be on the order of 10 - 100 kHz. In some cases, the first phase shifters 532, 832, 932, 932' may be used to perform large-scale steering corrections of the signal, and the second phase shifters 534, 834, 934, 934' may be used for noise correction and / or environmental variation correction (e.g., dithering).

[0059]

[0070] Also, as described above, the first phase shifters 532, 832, 932, 932' may be associated with each respective single emitter 520, 820, 920, 920', and the second phase shifters 534, 834, 934, 934' may be associated with a plurality of emitters 520, 820, 920, 920' among a plurality of emitters (e.g., two, four).

[0060]

[0071] In some cases, when the signal is an incident signal, the modulation at the first phase shifter may be performed before the modulation at the second phase shifter. In this regard, when receiving the signal at the emitters 520, 820, 920, 920' of the optical communication terminals 102, 122, the signal may be modulated by the first phase shifters 532, 832, 932, 932'. Thereafter, the signal may be further modulated by the second phase shifters 534, 834, 934, 934'.

[0061]

[0072] Alternatively, when the signal is an outgoing signal, the modulation at the second phase shifter may be performed before the modulation at the first phase shifter. In this regard, when transmitting the signal from the optical communication terminal, the signal may be modulated by the second phase shifters 534, 834, 934, 934'. Thereafter, the signal may be further modulated by the first phase shifters 532, 832, 932, 932' before being transmitted by the emitters 520, 820, 920, 920'.

[0062]

[0073] In some cases, the method may further include modulating the signal at a third update rate and within a third tuning range in the third phase shifter of the OPA. In this regard, the third update rate of the third phase shifter (e.g., the third phase shifter 936) may be the same as or different from the first update rate, and the third update rate may also be the same as or different from the second update rate. Additionally, the third tuning range of the third phase shifter 936 may be the same as or different from the first and / or second tuning ranges. In some cases, the third tuning range may include the same number of frequencies within the first and / or second tuning ranges. In some cases, the third phase shifter 936 may be used for larger-scale phase modulation. For example, the third phase shifter 936 may be used to perform large-scale steering corrections of the signal. Alternatively, the third phase shifter may be used for smaller-scale phase modulation. For example, the third phase shifter 936 may be used for noise or environmental variation correction (e.g., dithering).

[0063]

[0074] In some cases, if the signal is an incident signal, the modulation at the third phase shifter may be performed subsequent to the modulation at the first and second phase shifters. In this regard, when receiving the signal at the emitters 520, 820, 920, 920' of the optical communication terminals 102, 122, the signal may be modulated by the first phase shifters 532, 832, 932, 932'. Thereafter, the signal may be further modulated by the second phase shifters 534, 834, 934, 934', and then the signal may be further modulated by the third phase shifter 936. As described above, for simplicity and ease of illustration, only one third phase shifter is depicted in FIGS. 9A - 9B, but the OPA of the optical communication terminal may include one or more third phase shifters each associated with one or more of the plurality of emitters.

[0064]

[0075] Alternatively, when the signal is the emitted signal, the modulation in the third phase shifter may be performed before the modulations in the first and second phase shifters. In this regard, when transmitting a signal from the optical communication terminal, the signal may be modulated by the third phase shifter 936, and then, the signal may be further modulated by the second phase shifters 534, 834, 934, 934'. Thereafter, the signal may be further modulated by the first phase shifters 532, 832, 932, 932' before being transmitted by the emitters 520, 820, 920, 920'.

[0065]

[0076] The features and methods described herein can provide an optical communication terminal with an OPA using phase shifters having different tuning ranges and / or update rates. In this regard, the OPA can utilize the advantages of different tuning techniques while minimizing the drawbacks. Another major advantage of this architecture is the possibility of sharing phase shifters with different tuning techniques among multiple antennas or emitters. By sharing the phase shifters, the complexity of the system can be reduced and free space on the PIC can be freed up for other components, thereby improving scalability. Also, by cascading the phase shifters, the driver requirements for individual phase shifters can be reduced, for example, it becomes possible to imprint complex modulation patterns using simpler switches at each level.

[0066]

[0077] Unless otherwise stated, the foregoing alternative examples are not mutually exclusive and can be implemented in various combinations to achieve specific advantages. The above and other modifications and combinations of the features described above can be utilized without departing from the subject matter defined by the claims. Therefore, the foregoing description of the embodiments should be regarded as illustrative rather than limiting of the subject matter defined by the claims. Further, the provision of the examples described herein and phrases expressed as "such as" and "including" should not be construed as limiting the subject matter of the claims to specific examples. More precisely, these examples are intended to illustrate only one of many possible embodiments. Further, the same reference numerals in different drawings can identify the same or similar elements.

Description of Reference Numerals

[0067] 102, 122 Optical communication terminals 114, 134 OPA architectures 320 Multiple emitters 321, 322, 323, 324, 325, 520, 820, 920, 920’, 820a, 820b, 820c, 820d, 920a, 920b, 920c, 920d, 920a’, 920b’, 920c’, 920d’ Emitters 541, 543, 545, 547 Sets of phase shifters 532, 832, 932, 932’, 832a, 832b, 832c, 832d, 932a, 932b, 932c, 932d, 932a’, 932b’, 932c’, 932d’ First phase shifters 534, 834, 934, 934’ Second phase shifters 936 Third phase shifter 1000 Method for modulating a signal

Claims

1. An optical communication terminal, comprising: an optical phased array (OPA), the OPA comprising: A plurality of emitters; a set of phase shifters including a first phase shifter and a second phase shifter, the first phase shifter and the second phase shifter being arranged such that an incident signal is modulated by the first phase shifter at a first update rate and a first tuning range, and then further modulated by the second phase shifter at a second update rate and a second tuning range, the first update rate being different from the second update rate and the first tuning range being different from the second tuning range; Including, An optical communications terminal, wherein the first phase shifter is associated with at least one emitter of the plurality of emitters, and the second phase shifter is associated with at least two emitters of the plurality of emitters.

2. 2. The optical communication terminal of claim 1, wherein the first phase shifter and the second phase shifter are arranged such that an outgoing signal is modulated by the second phase shifter at the second update rate and the second tuning range, and then further modulated by the first phase shifter at the first update rate and the first tuning range.

3. The optical communications terminal of claim 1 , wherein the second phase shifter is associated with at least four of the plurality of emitters.

4. 2. The optical communications terminal of claim 1, wherein the set of phase shifters further comprises a third phase shifter having a third update rate and a third tuning range.

5. The optical communication terminal of claim 4 , wherein the second tuning range is the same as the third tuning range.

6. The optical communication terminal according to claim 4 , wherein the second update rate is the same as the third update rate.

7. 5. The optical communication terminal of claim 4, wherein the first phase shifter, the second phase shifter, and the third phase shifter are arranged such that an outgoing signal is modulated by the third phase shifter at the third update rate and the third tuning range, then further modulated by the second phase shifter at the second update rate and the second tuning range, and then further modulated by the first phase shifter at the first update rate and the first tuning range.

8. 5. The optical communication terminal of claim 4, wherein the first phase shifter, the second phase shifter, and the third phase shifter are arranged such that an incident signal is modulated by the first phase shifter at the first update rate and the first tuning range, then further modulated by the second phase shifter at the second update rate and the second tuning range, and then further modulated by the third phase shifter at the third update rate and the third tuning range.

9. 2. The optical communication terminal of claim 1, wherein the set of phase shifters is a plurality of sets of phase shifters each including a first phase shifter associated with at least one respective emitter of the second phase shifters associated with at least two respective emitters of the plurality of emitters.

10. 10. The optical communication terminal of claim 9, wherein the first phase shifter of the plurality of sets of phase shifters is disposed in a first layer, and the second phase shifter of the plurality of sets of phase shifters is disposed in a second layer.

11. 2. The optical communications terminal of claim 1, wherein the first tuning range is greater than 2.pi. and the first update rate is on the order of 1 kHz.

12. 2. The optical communication terminal of claim 1, wherein the second tuning range is less than π and the second update rate is on the order of 10 kHz to 100 kHz.

13. 2. The optical communication terminal according to claim 1, wherein the first phase shifter is a thermal-optical phase shifter.

14. 2. The optical communication terminal according to claim 1, wherein the second phase shifter is a carrier phase shifter.

15. 1. A method for modulating a signal in an optical phased array (OPA) of an optical communication terminal, the method comprising: modulating a signal at a first phase shifter of the OPA at a first update rate and a first tuning range; modulating the signal at a second update rate and a second tuning range in a second phase shifter of the OPA, the first update rate being different from the second update rate and the first tuning range being different from the second tuning range; Including, 11. The method of claim 10, wherein the first phase shifter is associated with at least one emitter of a plurality of emitters and the second phase shifter is associated with at least two emitters of the plurality of emitters.

16. 16. The method of modulating a signal of claim 15, wherein the modulation at the first phase shifter of the OPA is performed before the modulation at the second phase shifter of the OPA when the signal is an incident signal.

17. 16. The method of modulating a signal of claim 15, wherein the modulation in the second phase shifter of the OPA is performed before the modulation in the first phase shifter of the OPA if the signal is an outgoing signal.

18. 16. The method of modulating a signal of claim 15, further comprising modulating the signal at a third phase shifter of the OPA at a third update rate and a third tuning range.

19. 20. The method of modulating a signal of claim 18, wherein when the signal is an incident signal, the modulation in the first phase shifter and the second phase shifter of the OPA is followed by the modulation in the third phase shifter.

20. 20. The method of modulating a signal of claim 18, wherein the second update rate is the same as the third update rate.

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