WO2017011649A1 - Free-space optical networks with mechanically or non-mechanically steered and dynamically expanded laser beams - Google Patents

Free-space optical networks with mechanically or non-mechanically steered and dynamically expanded laser beams Download PDF

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Publication number
WO2017011649A1
WO2017011649A1 PCT/US2016/042265 US2016042265W WO2017011649A1 WO 2017011649 A1 WO2017011649 A1 WO 2017011649A1 US 2016042265 W US2016042265 W US 2016042265W WO 2017011649 A1 WO2017011649 A1 WO 2017011649A1
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Prior art keywords
transceiver
laser beam
method
non
mechanically
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PCT/US2016/042265
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French (fr)
Inventor
Liangping Ma
Ahmed AHMADEIN
Vincent Roy
Tanbir Haque
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Interdigital Patent Holdings, Inc.
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Priority to US201562192401P priority Critical
Priority to US62/192,401 priority
Priority to US201662329855P priority
Priority to US62/329,855 priority
Application filed by Interdigital Patent Holdings, Inc. filed Critical Interdigital Patent Holdings, Inc.
Publication of WO2017011649A1 publication Critical patent/WO2017011649A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/112Line-of-sight transmission over an extended range
    • H04B10/1121One-way transmission
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/112Line-of-sight transmission over an extended range
    • H04B10/1129Arrangements for outdoor wireless networking of information
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114Indoor or close-range type systems
    • H04B10/1141One-way transmission
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114Indoor or close-range type systems
    • H04B10/1149Arrangements for indoor wireless networking of information

Abstract

Systems, methods, and devices for implementing a free-space optical network. A laser beam may be modulated with data or control signals. The laser beam may be steered by passing it through a diverging lens and a polarization grating. The diverging lens may have a non-mechanically adjustable focal length, and the polarization grating may have a non-mechanically adjustable diffraction angle.

Description

FREE-SPACE OPTICAL NETWORKS WITH MECHANICALLY OR NON-MECHANICALLY STEERED AND DYNAMICALLY EXPANDED

LASER BEAMS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. 62/192,401 filed July

14th, 2015 and U.S. 62/329,855 April 29th, 2016 the contents of which are hereby incorporated by reference herein.

BACKGROUND

[0002] Free-space laser communication networks may be used to support extremely-high data rate and secure communication. Free-space laser communication has been used in data center networks. The laser beams in such applications have been mechanically steered towards the intended receivers.

[0003] Data centers have become a vital part of content provider networks and cloud applications. However, the cost and the size of data centers are increasing. Free space optical (FSO) communication is considered to be a good alternative to wired communication in such applications, and may add flexibility to the data center through non-mechanical or hybrid laser communication systems.

SUMMARY

[0004] Systems, methods, and devices for implementing a free-space optical network using a laser beam modulated with data or control signals. The laser beam may be steered by passing it through a diverging lens and a polarization grating. The diverging lens may have a non-mechanically adjustable focal length, and the polarization grating may have a non- mechanically adjustable diffraction angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:

[0006] FIG. 1A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented;

[0007] FIG. IB is a system diagram of an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A;

[0008] FIG. 1C is a system diagram of an example radio access network and an example core network that may be used within the communications system illustrated in FIG. 1A;

[0009] FIG. 2A is a ray diagram illustrating an example architecture for non-mechanical beam steering and expansion;

[0010] FIG. 2B is a ray diagram illustrating another example architecture for non-mechanical beam steering and expansion;

[0011] FIG. 3A is a ray diagram further illustrating the example architecture of FIG. 2A;

[0012] FIG. 3B is another ray diagram further illustrating the example architecture of FIG. 2A;

[0013] FIG. 4A is a block diagram illustrating an example system architecture;

[0014] FIG. 4B is a block diagram illustrating an example system architecture;

[0015] FIG. 5 is a beam diagram illustrating wherein a transmitter searches for a receiver by varying angles to form overlapping coverages;

[0016] FIG. 6 is a block diagram illustrating an example search algorithm.

[0017] FIG. 7 is a flow chart illustrating an example link establishment protocol including search and tracking; [0018] FIG. 8A is a perspective diagram illustrating an example multi- hop protocol;

[0019] FIG. 8B is a perspective view of an example data center system including a FSO solution; and

[0020] FIG. 9 is a perspective view of an example stacked multicore architecture.

DETAILED DESCRIPTION

[0021] The high carrier frequency of laser communications may provide high channel bandwidth. The use of free-space laser in complex and mobile networks has been limited due to limitations in mechanically steering the laser beams to search for, and track the communication nodes. As discussed herein however, the adaptation of free-space laser communication networks to mobility scenarios may be by mechanical, non-mechanical, or a hybrid of mechanical and non-mechanical steering and adaptive beam expansion, providing link establishment and multi-hop relay protocols, procedures to apply such steering, beam expansion, link establishment, and relay protocols to inter-chip communication and/or introducing auxiliary radios to serve as the control plane in assisting the link establishment, search, and tracking of data plane laser beams.

[0022] FIG. 1A is a diagram of an example communications system 100 in which one or more disclosed embodiments may be implemented. Various components of communications system 100 may include FSO laser communications transceivers, such as those discussed herein with regard to FIGS. 2-11. For example, WLAN 160 may include, form a part of, or communicate with a data center which includes servers which communicate wirelessly using FSO laser communications transceivers.

[0023] The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

[0024] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, consumer electronics, and the like.

[0025] The communications systems 100 may also include a base station

114a and a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0026] The base station 114a may be part of the RAN 104, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic region, which may be referred to as a cell (not shown). The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In another embodiment, the base station 114a may employ multiple -input multiple-output (MIMO) technology and, therefore, may utihze multiple transceivers for each sector of the cell.

[0027] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0028] More specifically, as noted above, the communications system

100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High- Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

[0029] In another embodiment, the base station 114a and the WTRUs

102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A). [0030] In other embodiments, the base station 114a and the WTRUs

102a, 102b, 102c may implement radio technologies such as IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0031] The base station 114b in FIG. 1A may be a wireless router, Home

Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a locahzed area, such as a place of business, a home, a vehicle, a campus, and the hke. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the core network 106.

[0032] The RAN 104 may be in communication with the core network

106, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 may provide call control, bilhng services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high- level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and/or the core network 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing an E-UTRA radio technology, the core network 106 may also be in communication with another RAN (not shown) employing a GSM radio technology.

[0033] The core network 106 may also serve as a gateway for the

WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0034] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular -based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0035] FIG. IB is a system diagram of an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display /touchp ad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment. [0036] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0037] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0038] In addition, although the transmit/receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116. [0039] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, for example.

[0040] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display /touchp ad 128 (e.g., a liquid crystal display (LCD) display unit or organic hght-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display /touchp ad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The nonremovable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0041] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0042] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0043] The processor 118 may further be coupled to other peripherals

138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0044] FIG. 1C is a system diagram of the RAN 104 and the core network 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the core network 106.

[0045] The RAN 104 may include eNode-Bs 140a, 140b, 140c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 140a, 140b, 140c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140c may implement MIMO technology. Thus, the eNode-B 140a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a. [0046] Each of the eNode-Bs 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and/or downlink, and the like. As shown in FIG. 1C, the eNode-Bs 140a, 140b, 140c may communicate with one another over an X2 interface.

[0047] The core network 106 shown in FIG. 1C may include a mobility management entity gateway (MME) 142, a serving gateway 144, and a packet data network (PDN) gateway 146. While each of the foregoing elements are depicted as part of the core network 106, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0048] The MME 142 may be connected to each of the eNode-Bs 140a,

140b, 140c in the RAN 104 via an Si interface and may serve as a control node. For example, the MME 142 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 142 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0049] The serving gateway 144 may be connected to each of the eNode

Bs 140a, 140b, 140c in the RAN 104 via the Si interface. The serving gateway 144 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144 may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0050] The serving gateway 144 may also be connected to the PDN gateway 146, which may provide the WTRUs 102a, 102b, 102c with access to packet -switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. [0051] The core network 106 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the core network 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the core network 106 and the PSTN 108. In addition, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0052] Other network 112 may further be connected to an IEEE 802.11 based wireless local area network (WLAN) 160. The WLAN 160 may include an access router 165. The access router may contain gateway functionality. The access router 165 may be in communication with a plurality of access points (APs) 170a, 170b. The communication between access router 165 and APs 170a, 170b may be via wired Ethernet (IEEE 802.3 standards), or any type of wireless communication protocol. AP 170a is in wireless communication over an air interface with WTRU 102d.

[0053] An example of a free space optical communication system is shown in FIG. 2 A and 2B. Non-mechanical steering and adaptive beam expansion may be incorporated into a fully optical transceiver design (not shown). For example, two components may be cascaded in the light path of a laser beam: a polarization grating 206 whose diffraction angle may be electrically adjusted, and a diverging lens, such as a concave lens 208 whose focal length may be electrically adjusted. In one embodiment the diverging lens may be a double concave, plano-concave, bioconcave, or any functionally equivalent lens. For example, in FIG. 2A a laser 210 may be modulated from a laser source 202 through a polarization grating 206 and a concave lens 208. FIG. 2B shows an alternative example where the polarization grating 206 may cascaded after the concave lens 208. The polarization grating 206 may be made using a polymer and a diffraction angle of the polarization grating 206 may be electrically adjustable. The polarization grating 206 may be or include a switchable polarization grating and/or a polymer polarization grating. In another example approach, the electrically adjusted polarization grating 206 may be replaced by other types of switches, such as a liquid crystal phase grating based switch, an electro-optical switch, a thermo-optical switch, a semiconductor amplifier-based switch, a mechanical switch (e.g., such as a micro-electro mechanical switch (MEMS)) and/or any other functional equivalent switch. The concave lens 208 may be made using liquid crystal, metamaterial, or one of their equivalents, and the focal length of the concave lens 208 may be electrically adjustable.

[0054] The arrangement shown in FIG. 2A may allow both the direction and width of a laser beam to be adjusted through electrical means, which may be commanded by control logic 204. Control logic 204 in FIG. 2B may be derived similarly to the architecture of FIG. 2A. The following notation is used in the present disclosure, and in relevant part FIG. 2 A, 3 A, and 3B:

d: the distance between the polarization grating 206 and the concave lens

a: the angle produced by the polarization grating 206 β: the laser beam expansion angle

y: the orientation of the expanded laser beam, i.e., the angle between the axis of the expanded laser beam and the optical axis.

[0055] The polarization grating 206 itself may include more than one module. For example, the polarization grating 206 may be a two-module design, which may include a fine steering module and a coarse steering module, further discussed with relation to FIG. 4A and 4B.

[0056] Control of the beam expansion angle is described in the ray diagram of FIG. 3A, which is described with respect to the architecture shown in FIG. 2A. For the ray diagram of FIG. 3A, let the radius of the beam exiting the polarization grating be r, the focal length of the concave lens 302 be /, the distance between the polarization grating and the concave lens 302 be d, and the distance between the image (e.g., beam pattern at the point it exits the laser source) A'B' to the concave lens 302 be x.

[0057] The Gaussian Thin Lens Formula (with the left-to-right direction as the positive direction) may then be expressed as:

-L + —= l

— x —a which gives:

fd

x

I d

[0058] To solve for the height of the image, let h=A'C, where C is the intersection between line A'B' and the optical axis. This yields: r fr

h = x— =

d f + d

[0059] Expansion angle components βΐ and β2, as shown in the ray diagram of FIG. 3B, may now be solved as follows: r + d tan a— h r + (/ + d) tan a

tan β1 =

x / r— d tan a— h r— f + d) tan a

tan β2 =

x f

[0060] Accordingly, the beam expansion angle 6 may be expressed as follows:

β = βι + β2 = tan"1

Figure imgf000015_0001

EQUATION 1 [0061] The equation 1 expresses details for controlling the beam expansion angle β by tuning the focal length / and the angle a.

[0062] The angle between the axis of the expanded beam and the optical axis may be expressed as:

Figure imgf000016_0001

EQUATION 2

[0063] The equation 2 expresses details for controlling the direction of the expanded beam by tuning the focal length / and the angle a.

[0064] Aiming a laser beam in a wireless laser communication network may present several challenges. First, the polarization grating may produce a finite number of angles, which may not be able to cover every direction in three-dimensional space. This may create difficulties in establishing a communication link between a transmitter and the receiver of such network, e.g., because the receiver may not be in any of the discrete directions covered by the transmitter. Expanding the laser beam by building upon the above formulation as explained in the following example, may address this challenge.

[0065] FIGS. 4A and 4B are block diagrams illustrating an example system architecture. The linearly polarized laser beam is modulated from a source (not shown) and passes through a quarter wave plate 408 that changes it to a circularly polarized laser beam after which it enters a beam steering module, such as the fine module 406 or the coarse module 404. The coarse module 404 may include multiple stages and each stage may include a half- wave plate 410, which may be turned off or on, and may include a polymer polarization grating 412 (i.e., a stage may include a series assembly of a half- wave plate 410 and polymer polarization grating 412). If the half-wave plate

410 is active (e.g., without having a voltage applied), a light with right-handed circular (RCP) polarization incident on the half-wave plate 410 is changed in polarization to left-handed circular polarization (LCP) and vice versa. It is noted that the half- wave plate 410 may introduce a phase difference of π between the ordinary light and the extraordinary light and consequently flip a RCP light to a LCP light and vice versa, as shown in FIG. 4A or 4B. On the other hand, if the half-wave plate 410 is not active (e.g., with a voltage applied), the half-wave plate 410 may not change the polarization of the light passing through. Control logic 204 (as shown in FIG. 2A and/or 2B) may be implemented to change the polarization of the light as it traverses the half- wave plate 410 and polymer polarization grating 412 series assembly. A polymer polarization grating 412 may change the direction of the light leaving the half-wave plate 410 to either the +1 diffracted order or -1 diffracted order based on the polarization of the light. As light traverses a stage of the coarse module 404, the direction may change once, either in the +1 diffracted order or the -1 diffracted order. The coarse module 404 may be configured to steer a laser beam into a finite number of directions with coarse granularity. The fine module 406 may be configured to provide a finer granularity to fill part or all of the gap between adjacent directions from the coarse module, e.g., by steering the laser beam into a finite number of directions using non- mechanical steering methods, such as those discussed herein, with a finer granularity than the coarse granularity; also, in an alternative embodiment either module may use mechanical devices to steer the beam. In one embodiment the fine module 406 may be cascaded after the coarse module as shown in FIG. 4B, or before the coarse module as shown in FIG 4A. In one embodiment the polymer polarization grating 412 may be substituted by a liquid crystal phase grating based switch, and electro optical switch, a thermo- optical switch, a semiconductor amplified switch, and/or a mechanical switch. Also in the examples of FIGS. 4A and 4B, dashed lines with arrows within the coarse module 404 indicate possible directions for the outgoing laser beams, and the solid lines with arrows indicate the actual directions taken by the input laser beam. For purposes of this example, it is assumed that the polarization grating produces angles

[0066] Referring to examples shown in FIG. 4A and 4B, the concave lens

414, as discussed previously herein, is used to assist in sweeping the laser beam across all directions and expanding the beam in order to locate a receiver. For each value of the pair (a, f)=(ai, fi), Equations 1 and 2 above may be used to solve for ¾) and yi, as referred to in FIG. 2A. To ensure continuous coverage, fi may be chosen such that:

Yi -—≤Yi+i — , i = 1, 2, ... , M - 1

[0067] In order to avoid spreading the energy over angles that are too wide, the following objective function may be minimized:

Figure imgf000018_0001

[0068] subject to the constraints:

Figure imgf000018_0002

[0069] FIG. 5 is a beam diagram illustrating the transmitter 502 may search for the receiver 504 by varying the angles yi and β(ί), where i=l, 2, ...M to form overlapping coverages.

[0070] If the transmitter 502 can cover all angles continuously, which may be the result of a narrow beam width of the laser, it may take a long time before the beam sweeps across the receiver 504. In order to speed up the process, it may be desired to expand the beam width. This may be approached similarly to the example above. For example, the problem may be formulated as the following optimization problem:

Figure imgf000019_0001

[0071] subject to the constraints:

Figure imgf000019_0002

Ύι ~ Ύκ > F

[0072] where F is the field of view of the transmitter 502.

[0073] FIG. 6 is a block diagram illustrating an example hybrid architecture incorporating an auxiliary radio 612 and a laser transceiver 610. It may be desirable to design physical layer and upper layer protocols to make high-speed free-space laser communication networks fully automated and enhance the adaptation and robustness of such networks. The laser source 610 may implement the data plane function (e.g., data transmission), and the RF radio 612 may implement the control plane function (i.e., auxiliary assistance in aiming, search and tracking). Links and connectivity may be established using a medium access control (MAC) 608 layer designed such that all servers can reach each other. The MAC 608 is reconfigurable and may automatically adapt to any changes and faults without manual intervention or offline configuration, except possibly during initial system layout. The MAC 608 may control data transmission/receipt and may be connected to a network 606, where in turn the data may go through transport 604, which in turn facilitates the delivery /receipt of data to/from an application 602.

[0074] FIG. 7 is a flow chart illustrating an example link establishment protocol including search and tracking for the hybrid design shown and described with respect to FIG. 6. For a fully optical (i.e. non-hybrid) design, the radio frequency "RF" referenced in the flow chart of FIG. 7 can be replaced with a wide (laser) beam. Similarly, for a fully optical design, the "RF Radio" of FIG. 6 can be replaced with a wide laser beam. Searching and tracking may be required for data centers to handle node changes and to allow for automatic re-configurability by the nodes. In one embodiment, changing or adding a cabinet or a rack may not require a human being to reconfigure the entire network or otherwise to intervene by using a search and tracking algorithm thereby enabling "plug-and-play" functionality for any node on the network.

[0075] Additionally, FIG. 7 shows an example embodiment for a coarse search algorithm. Fine search may be performed in a similar fashion, except that beam steering is performed over N regions or subsectors within one sector rather than over N sectors. In either coarse search or fine search, the entire system shown in FIG 4A or FIG 4B may be used to control both the direction and the width of the laser beam. In the embodiment a new node (e.g. rack or BS) may enter the network and may initiate a search sequence to locate neighboring nodes (e.g. racks and BSs). A transceiver, such as a BS, may have some "intelligence" and storage with which to maintain records of the nodes registered to it, and may share these records with other nodes. By maintaining and sharing registration records in this way, one or more of the BSs may determine how to communicate from one BS to another (or from one endpoint through multiple nodes to another end point).

[0076] During a first stage 702 of a searching algorithm a transceiver of the new node may transmit a wide laser beam with low bandwidth on a band assigned for search to scan a sector i. The beam width may be controlled by a digitally focal length-adjustable lens as described earlier. Such lens may be made with liquid crystal or metamaterial and may adaptively change its focal length in response to electrical signals. By changing the focal length of a concave lens, for example, it may be possible to change the width of a laser beam along the optical axis.

[0077] There may be two reserved bands; one for control and another for search. The transmitter of the new node may steer the beam using a non- mechanical beam steering mechanism, or a hybrid system, as discussed herein. In the next stage 704, a receiver (Rx) may estimate the signal to noise ratio (SNR). Following this, in stage 706 the receiver sends the best SNR record, of the estimate, to a transmitter (Tx), of the transceiver, using a low power RF module (in a hybrid approach) accompanied with the device ID (MAC address for example), or using a wide laser beam (in a pure optical approach) to convey the best SNR record to the transmitter in the direction opposite to the angle of arrival (AoA) or in multiple directions sequentially. At stage 708, the transmitter may update the corresponding receiver record with a SNR value, device ID, and sector ID; the receiver may also record the sector in which it receives the data from the transmitter by estimating the angle of arrival. This may enable the receiver to have an initial estimate of the transmitter's location, which may reduce the search time in a case where the receiver's and transmitter's roles are flipped and the current receiving device becomes a transmitter's while the current transmitter becomes the targeted receiver. At stage 710, the transmitter may then steer the beam to the next sector and collect SNR values from receivers that have detected the beam, where N refers to the total number of sectors to be scanned. In stage 712, if a recorded SNR from an earlier scan is lower (i.e. less favorable) than the current value, both transmitters and receivers may overwrite the record with the current value. Assessing stage 710 again, if i is not less than N, then no further searching is required and this is the end of the process, stage 714.

[0078] After the coarse search, the transmitter may have a list of all neighboring receivers and sectors that are reachable. The transmitter may then perform a second stage in fine. The fine search may follow the same procedure as the coarse search, except using a narrower beam within the sector with the highest SNR for that corresponding receiver (e.g. as established during the coarse search).

[0079] The computational complexity of the search and tracking algorithm may be analyzed as further discussed herein. Given that each transceiver may cover a certain area A that contains a number n of laser transceivers, the area of the searching beam in the coarse stage may be assumed to be a. Accordingly, the number N of sectors may be approximately N = A/a. The complexity of the coarse searching in 2D may be 0(N). Note that A»a, hence N may be quite large. However, it may be assumed that in some implementations the data center is considered fixed and that a transmitter does not need to execute the search frequently (e.g. once an hour or upon a reset trigger). Similarly, the complexity for fine searching may be 0(ηδα), where δ is an extra number of sectors around the chosen one from the coarse search. That is to say, fine search may be performed not only on the sector chosen from the coarse search but also on δ additional sectors around it in order to correct any misalignment errors from the coarse search stage. It is noted that fine search may be performed only the first time a transmitter selects one of the n transceivers found in the coarse stage and may not be repeated often.

[0080] In view of the foregoing, a FSO scheme for data centers using be non-mechanical beam steering may adapt to changes in the data center and may be automatically reconfigurable. Such schemes may use electrical beam steering and electrical focal length adapting lenses for search and tracking in a process described herein.

[0081] Joint power control and beam steering for maintaining a desired signal to noise ratio (SNR) is further discussed herein. For example, if a receiver is covered (e.g., the light beam from the transmitter reaches the receiver such that the receiver may receive at least a portion of a signal encoded in the light beam) by expanding the laser beam to shine on an area which includes the receiver, the SNR at the receiver will be lower than if the laser beam shone on the receiver without beam width expansion. In order to maintain link performance, power control may be required. Such power control may be implemented in various ways. For example, an iterative mechanism may be used. In an iterative approach, the receiver may first provide feedback channel quality information to the transmitter, and the transmitter may adjust the transmit power accordingly. The receiver may thereafter provide additional feedback regarding the channel quality as a result of the transmitter's power adjustment and the transmitter may adjust its transmit power again. This process may repeat until a desired channel quality is obtained at the receiver.

[0082] In one embodiment transceivers have perfect knowledge of the location of neighboring transceivers and the required angle with which it needs to direct its beams. In another embodiment transceivers do not have perfect knowledge of the location of neighboring transceivers and a process must be employed to determine the locations and angles required for directing its beams.

[0083] Existing search and tracking algorithms, such as for mechanical steering, may be used in conjunction with, or in place of, search and tracking algorithms based on non-mechanical steering capabilities as described herein [0084] FIG. 8A is a diagram illustrating an example multi-hop protocol.

The stationary relay nodes may be attached on the ceiling or the walls of a room, for example. A mobile laser node may send data (e.g. to another mobile laser node or a particular stationary node) in a multi-hop fashion if it cannot directly communicate with the intended end receiver. Data center networks differ in the number of servers and communication links, capacity of each server, and running services. A data center may generate a tremendous amount of data. For example, a data center with hundreds of servers, each supporting a data bandwidth of 10 Gigabits, may generate a data load on the network on the order of terabits per second. Due to interference in and relatively low speed of current wireless networks, current data centers use wired and optical fiber networks to handle the tremendous number of users and data flows in the network. Free space optical (FSO) communication may replace fiber cables in data centers

[0085] FSO data center solutions described herein may be fully or semi- automated and address problems of channel changes (blocking, misalignment, etc.) and device failures. Such solutions may be applied to server-to-server communications as well as inter-rack communications, may be scalable, and may easily be applied to data centers covering large areas. Such solutions may also include a search and tracking mechanism to automatically detect and adapt to any changes in the network or faults.

[0086] The example scenario of FIG. 8A may occur in a data center or other computer network environment. A FSO solution such as described herein may adapt easily to the physical environment and traffic changes of the data center, and may be equipped with searching and tracking algorithms to enable fast reaction to changes. Specifically, FIG. 8A shows a server and or a computer 806 that must communicate with other servers/computer 808. The servers/computers 806 and/or 808 may be associated with a transceiver, i.e. a mobile laser node 804 which transmits a laser beam 814 over a laser connection to a stationary node 802 in the event that a direct line of sight does not exist between the mobile laser nodes 804 associated with the server/computer 806 and servers/computers 808. In this example, the laser beam 814 may be transmitted to any number of stationary relay nodes 802 or mobile laser nodes 804 as necessary to reach the desired destination. Further in this embodiment, the server/computer may move physical location and a searching and tracking algorithm may facilitate automatic beam steering adjustment of both the stationary relay node 802 and/or the mobile laser node 804 to reestablish a direct line of sight or relay through one or more nodes 802 or 804 for sending a laser beam 814. Alternatively, there may be physical obstacles that may block a connection between a mobile laser node 804 and a stationary relay node 802 such that a new path for the laser beam 814 may have to be established automatically.

[0087] FIG. 8B is a perspective view of another example data center system including a FSO solution. In one embodiment racks which contains cabinets which contain servers. Each rack 810, cabinet 810, server 818, and/or other hardware (collectively called data center hardware) may be equipped with one or more transceivers, such as a FSO laser transceiver, and may be responsible for transmitting and receiving laser beams 814 to and from other data center hardware (e.g. neighboring racks). The term racks and cabinets are used interchangeably. The transceivers may be base stations 812 (BSs), relays, switches, receivers, transmitters, and/or hardware that facilitates the transmission of data (collectively called transceivers and interchangeable with one another in any example embodiment provided herein), in the sense that they may facilitate the transfer of data using laser beams transmitted from one area of the data center to another (such as in FIG. 8B). The transceivers may utilize wavelength division multiplexing (WDM), or any other equivalent, to enable communication with nearby data center hardware. The ceiling and walls may also be equipped with multiple transceivers, such as base stations 812, which may further facilitate communication between data center hardware. All of the elements of a FSO laser communications system, including but not limited to the data center hardware and transceivers, may be considered nodes on a network. Each transceiver may cover (i.e. receive and/or transmit over) a portion of the data center. Each data center hardware element may be registered to one of the transceivers to enable end-to-end connectivity, for example, with other data center hardware. As shown in FIG. 8B, connections may be facilitated between any data center hardware, for example between racks 810, between BSs 812 and racks 810, and/or between BSs 812. In one embodiment a BS 812 may cover a certain number of neighboring racks 810. In at least one embodiment, the base stations 812 utilize a search beam 816 to adapt to a change in the data centers of FIG. 8B environment or data center hardware. In one embodiment the base stations 812 may utilize search beams 816 to establish initial location information of all transceivers, such as base stations and transceivers associated with a server 818.

[0088] In one embodiment each data center hardware element may be equipped with a RF transceiver (not shown) , such as a low-power RF transceiver, for feedback and pre-search signaling as discussed herein. It is noted that the data center hardware may also be connected using Ethernet, optical fiber cables, or alternative wired means.

[0089] Each transceiver may be equipped with a non-mechanical beam steering device, as discussed with respect to FIGS. 2-8. Each beam steering device may incorporate a polymer polarization grating 206 and may maximize the field of regard (FOR) e.g. with a fine angular resolution. Further, each beam steering device may facilitate l-dimensional (ID) or two-dimensional (2D) beam steering. Various or uniform non-mechanical steering techniques may be used. Non-mechanical beam steering devices may be simple in their design and setup, have a fast response time, have large FOR, and may be compatible with other adaptation techniques for search and tracking. In some implementations, a transceiver is able to steer a beam by 65 degrees of angle in 1.7 milliseconds. Such additional steering capabilities may provide the system with more degrees of freedom in the initial design and layout.

[0090] Each transceiver may be connected to a small processing unit to process and forward packets towards their destinations. Transceivers may be added as desired to guarantee delivery and load balancing. However, installing too many transceivers may add interference as well as cost. The transceivers may be installed in such a way that no three transceivers are on the same line of sight. This allows each transceiver to target another transceiver using beam steering. Similar to the data center hardware, any of the transceivers may be equipped with a power RF transceiver (e.g. a low- power RF transceiver) which may be used to assist in search and tracking as discussed herein.

[0091] The connections between the nodes may be ad-hoc connections, in the sense that when a server needs to transmit data to another nearby server, it may exchange control signals using a band of the laser spectrum assigned only for control purposes. Any standard for control signals may be used, or adopted for use, with the FSO. The laser band may be suitable for such communications due to low interference (and thus lower chance of collision), and the wide bandwidth available within the laser band.

[0092] In one embodiment, a receiver may receive a request to send

(RTS) message from a transmitter, and the receiver may reply to the transmitter with a clear to send (CTS) message accompanied by information regarding empty bands/resources assigned to the transmitter for transmissions; in this embodiment utilizing WDM transceivers may be helpful. Further, in this embodiment scheduling algorithms similar to those found in cellular technology to manage the available bandwidth between different servers may be used. BSs may follow a similar connection methodology between one another to provide connectivity, and may reuse the same bands used by data center hardware, as there may be no (or minimal/negligible) interference.

[0093] It is not necessary for transceiver to be aligned on one line. It may be more reliable for the transceivers to be distributed geographically, which may mitigate certain types of failures (e.g., one broken transceiver blocking the communication path). In FIG. 8B, each BS 812 may connect with multiple other BSs within the same area. A BS 812 that wishes to send traffic can decide which node will be the next hop in the end-to-end transmission. This allows BSs to minimize the delay in reaching a destination. Moreover, it may permit further options in data center design, such as incorporating routing algorithms between different relay points and load balancing techniques.

[0094] In one embodiment, the server may transmit data to a BS 812 and the BS 812 then may distribute the data accordingly without the need for retransmissions from the server 818 which may result in efficient multicast. The BS 812 may also send the data to a targeted rack then to another BS 812 that will take over the job and send it to other targeted racks 810 or other BSs 812 and so on. In one embodiment legacy data center hardware may be reused, which provides for plug-and-play modifications based on FSO system elements described herein; for example, a data center that already has a mechanical beam steering setup may have non-mechanical beam steering transceivers added without modification to the existing setup. Further, the embodiments described herein may reduce calculation and power consumption load on the server side; also, information may be distributed among multiple BSs which may reduce the costs of retransmission from a BS compared with retransmission from a server using a wired connection or mechanically steered transceivers; additionally, a BS equipped with multiple transceivers may enable multiple concurrent transmissions to multiple nodes.

[0095] In larger data centers, a FSO laser system, such as the one described herein, may provide the ability to offload traffic from servers to BSs; also, transceivers can scale up or down by use of auto reconfiguration and adapting to changes in the data center. In smaller data centers, less capable switches may be used which may reduce the cost; a less capable switch may not require a high degree of "intelligence" (i.e. capability) or processing power as it may only receive packets from servers and forward them to the next switch or to targeted receivers in its geographical area based on a destination address and transmission protocols.

[0096] FIG. 9 shows an embodiment of Inter-chip and intra-chip communication, as further discussed herein. As the size of computer chips (and other microprocessors and integrated circuits) decreases, the effects of parasitic capacitance and/or inductance of wires connecting the chips may begin to influence the design. Further, 3D stacked multicore architectures have been proposed, for example, using microwave waveguides as the communication means between the chips or by using wireless laser links. Microwave waveguides may suffer from complex waveguide layout and the crosstalk between crossing waveguides. Implementing wireless laser links may offer a flexible structure. Beam steering techniques discussed herein may be applied to inter- or intra-chip communication.

[0097] FIG. 9 is a perspective view of an example stacked multicore architecture. FIG. 9 illustrates multiple processor cores 902 and one controller 904, although various other possible topologies will be evident to those having skill in the art (e.g., multiple controllers). In this example, the adjacent cores are connected by wires, and can communicate directly via the wires. Non-adjacent cores may use other cores as relays to carry traffic between them, or may use laser beams 906 to communicate.

[0098] The controller 904 may determine whether wires 908, laser beams 906 or a combination of wires 908 and laser beams 906 are used for communication between two cores. In the case of laser beam communication, the laser beams 906 may be controlled in various ways.

[0099] For example, the controller may dictate the orientation of a laser beam 906, and the core 902 may configure the parameters of the laser transmitter (as described earlier) to steer the laser beam 906 to that particular orientation following the procedures described earlier in the disclosure. A possible advantage of this approach is that the controller may have a centralized view of all cores and may develop collision free access schedules. A collision occurs, for example, if two beams of the same frequency shine on the same core.

[00100] In another example, the controller 904 may instruct a core 902 which other core it will communicate with, and may leave the decision on the orientation of the laser beam to that core 902. The core 902 may look up the location of the target core (e.g., in a locally stored table), may decide on the orientation of the laser beam 906, and thereafter may configure the laser transmitter to shine on the target core using this information.

[00101] It is noted that the laser beams may use a single frequency or multiple frequencies (e.g., red laser, green laser, etc.) With multiple frequencies available, wavelength division multiplexing (WDM), or any equivalent thereof, may be used such that system capacity may be improved and the chances of collision may be reduced.

[00102] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer- readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD- ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver or a laser transceiver for use with or in a WTRU, UE, terminal, base station, RNC, server, rack, or any host computer.

* *

Claims

CLAIMS What is claimed:
1. A method for implementing a free-space optical network comprising:
modulating, from a first transceiver, a laser beam with data or control signals; and
steering, from the first transceiver, the laser beam to a second transceiver by passing the laser beam through one or more electrically controllable steering modules and a diverging lens with an electrically adjustable focal length.
2. The method of claim 1, wherein:
the one or more steering modules comprises a coarse module and a fine module;
the fine module, the coarse module, or both the fine and the coarse modules comprise a plurality of stages; and
each of the plurality of stages comprises a switchable half-wave plate and a polarization grating with an adjustable diffraction angle.
3. The method of claim 2, wherein the polarization grating is non- mechanical and electrically adjustable.
4. The method of claim 2, wherein the polarization grating comprises a polymer material.
5. The method of claim 2, wherein the polarization grating is replaced with a liquid crystal phase grating based switch, an electro optical switch, a thermo-optical switch, a semiconductor amplified switch, or a mechanical switch.
6. The method of claim 2, wherein the fine module comprises mechanical components and the coarse module comprises non-mechanical components, or the fine module comprises non-mechanical components and the coarse module comprises mechanical components.
7. The method of 1, wherein the first transceiver is one of a base station (BS), a relay, a switch, a receiver, or a transmitter.
8. The method of claim 1, wherein the first transceiver is connected to a rack, a cabinet, or a server.
9. The method of claim 1, wherein the first transceiver is located on a wall, a ceiling, a floor, or any combination thereof.
10. The method of claim 1, wherein the diverging lens is one of a concave lens, a bioconcave lens, a double concave lens, or a plano-concave lens.
11. The method of claim 1, further comprising searching, by the second transceiver, for the laser beam according to an algorithm by scanning one or more sectors of one or more regions based on a signal-to-noise ratio (SNR) value.
12. The method of claim 11, further comprising storing, by the second transceiver, the SNR value received during the searching on a condition that the SNR value is lower than a value previously stored and pertaining to a previously scanned sector.
13. The method of claim 1, further comprising transmitting data using the laser beam and transmitting control signals using a radio frequency transmitter.
14. The method of claim 1, further comprising transmitting data via the laser beam from the first transceiver using wavelength division
multiplexing (WDM).
15. A free-space optical rack comprising:
one or more servers; and
a transceiver communicatively coupled to the one or more servers;
wherein the first transceiver comprises:
a laser modulator;
a polarization grating;
a concave lens;
a processor;
a non-transitory storage medium; and
a receiver.
16. The free-space optical rack of claim 15, wherein the polarization grating and concave lens are non-mechanically controlled by the processor.
17. The free-space optical rack of claim 15, wherein the first transceiver is configured to non-mechanically steer a laser beam to a second transceiver, and the second transceiver is configured to relay the laser beam to a third transceiver by mechanically steering the laser beam.
18. A free space optical inter/intra chip communication network, comprising:
a plurality of processor cores;
at least one controller; and
wherein the controller determines to send data from a first processor core to a second processor core via a laser beam instead of a wired connection.
19. The free space optical inter/intra chip communication network of claim 18, wherein the controller non-mechanically configures an orientation of the laser beam between the first processor core and the second processor core.
20. The free space optical inter/intra chip communication network of claim 18, further comprising a polarization plate non-mechanically controlled by the controller.
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