Deep space optical communications(深空光通信深空光通信)uSendingandreceivingdatafromspacecraftshasbeenachallengingproblemsince1950suCommunicationoverdeep-spacedistancesisextremelydifficult,muchmoredifficultthansatellitecommunicationsuCommunications beams spread as the square of thedistancebetweenthetransmitterandthereceiver2ThedistancefromEarthtoNeptuneorPlutocanbeontheorder of 4,000,000,000 km.After propagating over such adistance,the communications beam from a spacecraft willspreadtoanarea10billiontimes(
