High speed free-space optical communications

Abstract

High power, high speed VCSEL arrays are employed in unique configurations of arrays and sub-arrays. Placement of a VCSEL array behind a lens allows spatial separation and directivity. Diffusion may be employed to increase alignment tolerance. Intensity modulation may be performed by operating groups of VCSEL emitters at maximum bias. Optical communications networks with high bandwidth may employ angular, spatial, and/or wavelength multiplexing. A variety of network topologies and bandwidths suitable for the data center may be implemented. Eye safe networks may employ VCSEL emitters may be paired with optical elements to reduce optical power density to eye safe levels.

What is claimed: 
     
         1 . An optical communications device for free-space optical communication, comprising:
 one or more clusters of laser emitters configured to emit one or more laser beams;   an optical diffusing element configured to receive the one or more laser beams and output a diffuse cone for each of the one or more laser beams;   one or more collimating lenses configured to combine the diffuse cone into a bundle of laser beams;   one or more collection lenses configured to receive and focus the bundle of laser beams into a focused bundle of laser beams; and   one or more clusters of laser detectors configured to receive the focused bundle of laser beams from the one or more collection lenses, wherein each cluster of detectors is configured to be optically coupled with a corresponding cluster of emitters by the one or more collimating lenses and the one or more collection lenses.   
     
     
         2 . The optical communications device of  claim 1 , wherein the bundle of laser beams is configured to over-fill or under-fill the one or more collection lenses based on a desired amount of translational tolerance. 
     
     
         3 . The optical communications device of  claim 2 , further comprising a photovoltaic device configured to surround each laser detector among the one or more clusters of laser detectors to collect excess laser energy when the bundle of laser beams is configured to over-fill the one or more collection lenses. 
     
     
         4 . The optical communications device of  claim 1 , wherein bundle of laser beams is a combination of the one or more laser beams, and wherein the one or more laser beams in the combination is not coherent. 
     
     
         5 . The optical communications device of  claim 1 , wherein the one or more collection lenses is configured to focus the bundle of laser beams at a focal point behind a surface of the one or more clusters of detectors so the focused bundle of laser beams forms a blur circle at the surface of the one or more clusters of detectors. 
     
     
         6 . The optical communications device of  claim 5 , wherein the focal point is based on a desired translational tolerance and a desired optical power of the focused bundle of laser beams. 
     
     
         7 . The optical communications device of  claim 1 , further comprising one or more drivers, and wherein each of the one or more clusters of laser emitters include two or more VCSEL elements configured to be electrically connected in parallel and driven by a single driver among the one or more drivers. 
     
     
         8 . The optical communications device of  claim 1 , wherein:
 the one or more clusters of laser emitters are centrally located on a surface and are driven by an independent controlling circuit; and   the one or more clusters of laser detectors are located distally to the one or more clusters of laser emitters.   
     
     
         9 . The optical communications device of  claim 8 , wherein the one or more clusters of laser emitters are arranged in a linear array. 
     
     
         10 . The optical communications device of  claim 8 , wherein the one or more clusters of laser emitters are arranged in a two-dimensional array and the one or more clusters of laser detectors form a perimeter around the plurality of emitters. 
     
     
         11 . The optical communications system of  claim 1 , wherein the one or more collection lenses are configured to blur the focused bundle of laser beams based on a desired alignment tolerance or link budget. 
     
     
         12 . A system for the optical free-space transmission of a string of binary data, the system comprising:
 a first cluster of laser emitters associated with a first output level;   a second cluster of laser emitters associated with a second output level, the second cluster of laser emitters comprising a greater number of laser emitters than the first cluster of laser emitters;   circuitry configured to determine a first activation state for the first cluster of laser emitters during a clock pulse, the first activation state based on a binary value at a first bit position in the string of binary data; and   circuitry configured to determine a second activation state for the second emitter cluster during the clock pulse, the second activation state based on a binary value at a second bit position in the string of binary data.   
     
     
         13 . The system of  claim 12 , wherein the first cluster of laser emitters and the second cluster of laser emitters are configured to operate so as to reduce distortion. 
     
     
         14 . The system of  claim 12 , wherein the second cluster of laser emitters has twice the number of laser emitters as the first cluster of laser emitters. 
     
     
         15 . The system in  claim 10 , further comprising one or more additional clusters of laser emitters, wherein each additional cluster of laser emitters among the one or more additional clusters of laser emitters has twice the number of laser emitters as a most significant binary group of laser emitters from a prior cluster of laser emitters. 
     
     
         16 . The system of  claim 10 , further comprising a holographic optical element and lens configured to receive the output of the first cluster of laser emitters and the second cluster of laser emitters and form a uniform intensity beam. 
     
     
         17 . A system for the optical free-space transmission of a string of binary data, the system comprising:
 a first cluster of laser emitters associated with a first output wavelength;   a second cluster of laser emitters associated with a second output wavelength;   circuitry configured to determine a first activation state for the first cluster of laser emitters during a clock pulse, the first activation state based on a binary value at a first bit position in the string of binary data; and   circuitry for configured to determine a second activation state for the second cluster of laser emitters during the clock pulse, the second activation state based on a binary value at the second bit position in the string of binary data;   
     
     
         18 . The system of  claim 14 , further comprising a holographic optical element and lens configured to receive output from the first cluster of laser emitters and the second cluster of laser emitters and form a combined beam. 
     
     
         19 . The system of  claim 14 , wherein the first output wavelength and the second output wavelength are adjusted to an eye safe wavelength. 
     
     
         20 . The system in  claim 17 , further comprising one or more additional clusters of laser emitters, wherein each additional cluster of laser emitters among the one or more additional clusters of laser emitters is associated with an additional output wavelength and each additional cluster of laser emitters has twice the number of laser emitters as a most significant binary group of laser emitters from a prior cluster of laser emitters. 
     
     
         21 . An optical communications device for free-space optical communications capable of non-mechanical beam directivity, the device comprising:
 a lens;   a plurality of laser emitters positioned behind a lens, each of the plurality of laser emitters configured to emit a laser beam travelling a distinct optical path through the lens; and   circuitry configured to activate one of the plurality of laser emitters based on a desired optical path for the laser beam.   
     
     
         22 . The device of  claim 21 , wherein the plurality of laser emitters are configured in a linear array. 
     
     
         23 . The device of  claim 21 , wherein the plurality of laser emitters are configured in a two-dimensional array. 
     
     
         24 . The device of  claim 21 , wherein the plurality of laser emitters are configured in a three-dimensional arrangement of outward-facing arrays. 
     
     
         25 . A free space optical communications network comprising:
 a first surface;   a cluster of laser detectors connected to the first surface;   a second surface; and   an optical switch connected to the second surface, the optical switch comprising:
 a cluster of laser emitters configured to emit a laser beam; 
 one or more optical elements configured to receive the laser beam and output a beam striking the cluster of laser detectors; and 
 circuitry configured to transmit information to the cluster of laser detectors by driving the cluster of laser emitters. 
   
     
     
         26 . The optical communications network of  claim 25 , wherein the first and second surfaces are interior to an equipment rack. 
     
     
         27 . The optical communications network of  claim 25 , wherein the first surface is located on a first equipment rack and the second surface is located on a second equipment rack. 
     
     
         28 . The optical communications network of  claim 25 , wherein the first surface is located above an equipment rack. 
     
     
         29 . A free space optical communications network comprising:
 a first surface;   a first cluster of laser detectors connected to the first surface;   a second surface; and   a transceiver connected to the second surface, the transceiver comprising:
 a cluster of laser emitters configured to emit a laser beam; 
 a second cluster of laser detectors; 
 one or more optical elements configured to receive the laser beam and output a beam striking the first cluster of laser detectors; and 
 circuitry configured to transmit information to the first cluster of laser detectors by driving the cluster of laser emitters. 
   
     
     
         30 . The optical communications network of  claim 29 , wherein the second surface is located above an equipment rack. 
     
     
         31 . An eye safe free space optical communications system comprising:
 a laser emitter cluster emitting a laser beam carrying data; and   an optical element shaped as a clear planar surface having a first side and a second side, the optical element configured to receive the laser beam at the first side and spread an output of the laser beam over an area of the second side sufficient to reduce a power density of the laser beam to an eye safe level.   
     
     
         32 . The optical communications system of  claim 31 , wherein the optical element is located on or in a table top. 
     
     
         33 . The optical communications system of  claim 31 , wherein the output from the optical element delivers a wide beam of data to one or more receivers. 
     
     
         34 . The optical communications system of  claim 31 , wherein the optical element is mounted on or in a wall or ceiling. 
     
     
         35 . The optical communications system of  claim 31 , further comprising an optical filter coupled to a receiver. 
     
     
         36 . The optical communication system of  claim 35 , wherein the emitter is polarized and the optical filter is polarized. 
     
     
         37 . The optical communication system of  claim 31 , further comprising a window filter blocking transmission of wavelengths associated with the emitter. 
     
     
         38 . The optical communication system of  claim 30 , further comprising:
 a first detector associated with a first channel of information and a first signal strength;   a second detector associated with a second channel of information and a second signal strength; and   circuitry configured to select the first channel of information or the second channel of information based on the first signal strength and the second signal strength.   
     
     
         39 . An eye safe free space optical communications system comprising:
 a laser emitter cluster emitting a laser beam carrying data;   a transmitter for receiving the laser beam and creating a spread laser beam that is spread over an area sufficient to reduce a power density of the laser beam to an eye safe level; and   a protective cover for placement over the transmitter.   
     
     
         40 . The optical communications system of  claim 39 , wherein the protective element is located on or in a table top. 
     
     
         41 . The optical communications system of  claim 39 , further comprising one or more receivers for receiving the spread laser beam, wherein the spread laser beam delivers a wide beam of data to the one or more receivers. 
     
     
         42 . The optical communications system of  claim 39 , wherein the protective element is mounted on or in a wall or ceiling. 
     
     
         43 . The optical communications system of  claim 39 , further comprising an optical filter coupled to a receiver; 
     
     
         44 . The optical communication system of  claim 43 , wherein the emitter is polarized and the optical filter is polarized. 
     
     
         45 . The optical communication system of  claim 39 , further comprising a window filter blocking transmission of wavelengths associated with the emitter. 
     
     
         46 . A free space optical communications receiver system for a mobile device, comprising a receiver for receiving a spread laser beam carrying data from a transmitter that received a laser beam from an emitter cluster and created the spread laser beam that was spread over an area sufficient to reduce a power density of the laser beam to an eye safe level. 
     
     
         47 . The receiver system of  claim 46 , wherein the spread laser beam delivers a wide beam of data to the receiver. 
     
     
         48 . The receiver system of  claim 46 , further comprising an optical filter coupled to the receiver. 
     
     
         49 . The receiver system of  claim 48 , wherein the emitter cluster is polarized and the optical filter is polarized. 
     
     
         50 . An optical switching device comprising:
 a first cluster of laser emitters emitting a first laser beam;   a second cluster of laser emitters emitting a second laser beam;   a first optical element coupled to a first channel;   a second optical element coupled to a second channel;   a lens configured to receive the first laser beam and output a beam directed to the first optical element;   a lens configured to receive the second laser beam and output a beam directed to the second optical element; and   circuitry configured to drive the first cluster of laser emitters based on data to be transmitted to the first channel, and to drive the second cluster of laser emitters based on data to be transmitted to the second channel.   
     
     
         51 . The optical switching device of  claim 50 , wherein a single lens includes the lens configured to receive the first laser beam and the lens configured to receive the second laser beam. 
     
     
         52 . The optical switching device of  claim 50 , further comprising one or more additional optical elements. 
     
     
         53 . The optical switching device of  claim 50 , wherein the one or more additional optical elements include at least one of a diffuser, a mirror, and a MEMS device.