1、2023-2-9光宇宙通信重力波検出卫星用光宇宙通信重力波検出光宇宙通信重力波検出卫星用卫星用光宇宙通信重力波検出卫星用光波通信（）広周波数帯域確保。従大容量伝送可能。（）通信装置小型化可能性。重力波検出衛星回路素子、S/N考方、回線設計法、光宇宙通信類似性強。光宇宙通信重力波検出卫星用Fig.1 Configuration of a light wireless system.INFOINFOMOD/AMPMOD/AMPLIGHT LIGHT SOURCESOURCEPHOTOPHOTODETECTODETECTOR ROPTICAL RECEIVEROPTICAL RECEIVEROPTI
2、CAL TRANSMITTEROPTICAL TRANSMITTERTRANSMITTINGTRANSMITTINGANTENNAANTENNAINFOINFORECEIVINGRECEIVINGANTENNAANTENNAOptical signalOptical signalElectric signalElectric signalPROPAGATIONPROPAGATIONMEDIAMEDIA光宇宙通信重力波検出卫星用図光伝送系光構成光宇宙通信重力波検出卫星用2.2 Transmission of signal power by light The received light pow
3、er Pr:Pr=PtGtLfLaGr(1)where Pt is the output of an optical transmitter,G is the gain of a light wave antenna,subscripts t and r express transmission and reception,respectively,Lf is the free space loss between transmission and reception,and La is the additional loss according to absorption,scatterin
4、g,etc.Antenna gain in the direction of the front:G=(D/)2(2)where is wavelength,is the efficiency decided by the field distribution on the aperture,etc.,D is the aperture diameter of an antenna.Accordingly.Lf=(/4R)2(3)where R is the distance between transmission and reception.As a typical example,a l
5、ink between a GEO satellite and a LEO satellite:-67.1dBm versus-40 dBms of an optical fiber repeater.光宇宙通信重力波検出卫星用表1光回線解析（=0.85m）項目数値備考光出力20dBm100mW送信利得104.4dBD=0.1m,=0.2自由空間損失-295.9dBR=4.2x10m受信利得104.4dBD=0.1m,=0.2受信光電力-67.1dBm光宇宙通信重力波検出卫星用光信号電気信号直：（）直接検波、（）（）検波 光宇宙通信重力波検出卫星用図光検波回路図中間周波（IF）信号光宇宙通信重
6、力波検出卫星用検波光信号波e(t)a(t)cos(t+)（）光局部発振波e(t)acos(t)（）電力Ke（）検波器出力電流SD電力（）SD：検波器感度、SD=q/hf、光周波数混合器（光）出力電流i(t)、cos(-)t+cos(+)t+電気信号i(t)更高周波数光 （）光宇宙通信重力波検出卫星用信号電力 （）光信号波電力P、局発電力P（）、（）光宇宙通信重力波検出卫星用光満条件（）戻光Pr最小検出Pmin上回PrPmin（）Pmin、干渉処理必要S/N受信系雑音特性決。（）次右衛星折返再放射光、一部反射、発振至送受分離器DIP分離不完全、LdipPt受信器Rx入。従、DIP入口経送信光、元
7、小条件PtLdipGarGaifGatPt（）同、右放射光空間折返戻、PtLGarGaifGatPt（）空間折返光減衰Lsr、伝搬路上散乱反射現象決。（）左衛星放射後戻来光、右衛星折返 来光対、充分小必要、PtGtLfGrPtLdip（）PtGtLfGrPtL（）光宇宙通信重力波検出卫星用2.3 Noises generated in a receiver The shot noise ins2:=2q(iso+id)BM 2+x(6)where id:diode dark current,x:excess noise factor,and B:the frequency band width
8、 in baseband.Thermal noise by a load resistance RL,:=4kTB/RL.(7)Thermal noise by an amplifier:=(F-1)4kTo B/RL(8)where F:amplifier noise figure and To:standard temperature(290 deg.C).The total noise is expressed by the sum of Eqs.(6),(7),and(8).Shot noise restriction,and thermal noise restriction.光宇宙
9、通信重力波検出卫星用*amplifier:RL=50k,T=290K,F=2 Modulation schemeIntensity modulation(IM)Detection schemeDirect detection(DD)Detector diode PD(M=1,=1)APD(M=103,x=0.5,=1)Signal:Eq.(5)133pA133nAShot noise:Eq.(6)Thermal noise:Eqs.(7)+(8)*Table 2 Electric signal and noise at the mark reception光宇宙通信重力波検出卫星用検波雑音雑音
10、電力（）B：中間周波数段帯域幅。局発電力充分大NRqSPBIF（）雑音優勢、信号Pr依。時（）特色（直接検波比）（）検波器出力電流i(t)、e(t)比例（位相情報有）。従、AM、FM、PM可能（cf.直接検波IM）（）S/NP比例、信号雑音増加無。（）B狭、S/N良。光宇宙通信重力波検出卫星用極微弱光受信場合、上式量子性基雑音（量子雑音）発生。1波長光対、hf/21.8810Joule 9.4x10-20 W/Hz（）従受信Pr、下記値充分大必要。9.4x10E-20B（W）B（Bm）（）帯域B、系安定性決。例B=1kHz、Prc=-130.3dBm。従量子 雑音、無視。光宇宙通信重力波検出卫
11、星用2.4 Communication quality The S/N of an electric signal under thermal noise restriction:S/N=K1/R4(9a)and(9b)where the circumference temperature T is presupposed to be equal to T0.The noise exists any time regardless of the signal.The S/N under shot noise restriction:S/N=K2/R2(10a)and(10b)The shot
12、noise increases when a level is high:selection of the discrimination level of the mark and space.光宇宙通信重力波検出卫星用重力波検出衛星通信品質（）最終的情報、送出光（基準光）戻光（信号光）干渉 的光変化、PD電気信号変換（）干渉縞判別S/N（電気）必要。（）基準光充分強出来。従戻光極微弱、雑音制限域（検波同）。（）折返衛星、受信光自由発振干渉状態一定制御。観測周波数消、帯域（例Hz以下）雑音充分抑 必要。光宇宙通信重力波検出卫星用図Comparison between a lightwave a
13、ntenna and telescope光宇宙通信重力波検出卫星用The method of designing a diffraction limit light wave antenna with incidence of the Gaussian beam.The length of a light wave antenna:important,especially on a satellite.F/D where F is a focal length:(1)radio wave antenna;F/D=0.3(2)Hubble telescope;F/D=3,(3)SILEX;F/D
14、=2.4.Reflector shaping makes F/D small for single wavelength.However,the high efficiency design will be degraded significantly by the mechanical error.Antennas for an indoor light wireless LAN or an IrDA system can be given by a geometric optical method.光宇宙通信重力波検出卫星用Fig.4 Example of design of a high
15、-efficiency light wave antenna光宇宙通信重力波検出卫星用光波伝搬特性（）宇宙減衰。（）天体他光波源干渉混入。光宇宙通信重力波検出卫星用Fig.9 Applications of light wave communications between satellites.光宇宙通信重力波検出卫星用Fig.10 SILEX system configuration.光宇宙通信重力波検出卫星用波長帯0.8-0.85m光出力60mW速度50Mbps(GEO-LEO)2Mbps(LEO-GEO)望遠鏡口径0.25m指向精度0.3rad(random)0.8rad(static
16、)装置重量160kg表SILEX元光宇宙通信重力波検出卫星用OutlineofOICETSLaunch dateNov.in 2000 or laterLaunch vehicle Three-stage J-I rocketLaunch siteTanegashima space centerMission lifeMore than one yearWeightApprox.550 kgOrbit altitudeApprox.600 kmOrbit inclination35 degreesAttitude control Three-axis stabilizedFrom NASDA光
17、宇宙通信重力波検出卫星用OutlineofLUCETerminal mass:approx.130 kgPower consumption:approx.280 WWavelength:847 nm(transmission)819 nm(receiving)Bit rate:2.048 Mbps(Forward link)49.3724 Mbps(Return link)Optical antenna diameter:0.26 mObscuration ratio:0.2Truncation ratio:2.364Wavefront error:800 nm/10 r.m.sFrom NASDA光宇宙通信重力波検出卫星用PointingErrorBudgetsFrom NASDA光宇宙通信重力波検出卫星用図初期捕捉追尾光宇宙通信重力波検出卫星用図SAGITTARIUS 光学系光宇宙通信重力波検出卫星用重力波検出衛星実現、以下研究課題考。（）周波数安定度出力効率e.g.SagittariusNd:YAG（）出力（）光鏡面修整開口能率（大、重）所望開口面分布：製作誤差、微調機構2023-2-9光宇宙通信重力波検出卫星用
