A phase coherent optical link through the turbulent atmosphere Mini-DOLL : Deep Space Optical Laser Link

Transcription

1 A phase coheren opical link hrough he urbulen amosphere Mini-DOLL : Deep Space Opical Laser Link Presened b : Khelifa DJERROUD people involved : Acef Ouali SYRTE Clairon AndréSYRTE Lemonde Pierre SYRTE Man Nar Caherine ARTEMIS/OCA Samain Eienne Géo-Azur/OCA Wolf Peer SYRTE 1

2 Ouline Conex and ineress of coheren laser links Mini-DOLL : projec progress 3 seps 1. Firs sep: Mini-DOLL ground ground link: Turbulence noise Experimenal seup Laes resuls Applicaions of he saellie ground coheren opical links Frequenc comparison of disan clocks Conclusion and Perspecives 2

3 Conex : Aomic clocks : 2 x10-17 < 5 x10 4 s Conex and ineress Disribuion of aomic clock signals : iner comparison of clocks, navigaion of saellies, broadband communicaion, ime disseminaion, Oher applicaions : space geodes, space oceanograph, Earh and solar ssem gravi, Fundamenal phsics : Fuure missions require opical links SAGAS, ODYSSEY, LATOR, BEACON,... Ineres of a coheren laser link vs. pulsed link? Opical phase measuremens poeniall allows an improvemen 4 orders of magniude pulse duraion /opical period, implemened in he fiber links. Advanages: high accurac, low sensiivi o inensi flucuaions, insensiive o parasiical ligh cf. AM FM Radio Disadvanages: sensiive o he amospheric urbulence ransverse and emporal coherence, power requiremens. 3

4 3 essenial seps: Projec progress 1.Mini-DOLL ground ground wih a saionar arge CCR : corner cube reflecor: sud of he urbulence effecs for a horizonal propagaion. 2.Achieving an experimenal seup a SYRTE planned for he ground saellie link high power laser, freq. sabilizaion, Doppler shif ± 10 GHz... 3.Mini-DOLL saellie ground : Insall seup a he OCA on MeO LLR elescope, firs ess on exising saellies equipped wih a CCR JASON 1 and 2, TerraSAR-X,... Objecives: - Demonsrae he feasibili - Sud he urbulence limiaions - Sud he poenial limiaions of laser power - Sud he opimal size of he elescope adapive opics? - Sud he poenial for daa ransmission b phase modulaion

5 Mini-DOLL ground ground link: Turbulence noise Turbulence noise model Laser noise f 0 f 1 Laser noise and urbulence noise for an horizonal pah of 5 km roundrip ime, T = 16,6 µs f 0 = 0.05 Hz e f 1 = 1x10 4 Hz correspond o L 0 = 100 m, l 0 = 3 mm, v = 5 m/s 5

6 Mini-DOLL ground ground link: Experimenal seup 200 MHz Pol. φ = π / PBS 2 M1 M2 PI VCO Amp. monioring Couner Amosphere Laser λ/2 275 mw λ/4 CC 200 MHz AOM MC 10 mw λ/2 2.5 km T=16.6 µs Michelson 1064 nm Heerodne deecion Ampliude monioring Telescope diameer: 1.5 m Beam diameer: 38 cm CCR diameer : 5 cm 3 m 6

7 Mini-DOLL ground ground link: Experimenal seup M 3 M 4 Some characerisics of MeO Telescope: M 1 Øof elescope 1,5 m Grandissemen : 50 Øa he enrance of he elescope: 76 mm Øa he exi of he elescope: 38 cm M 6 M 5 2 m M 7 Some characerisics of MeO Telescope: Telescope diameer : 1.5 m Beam Øa he enrance : 76 mm Beam Øa he exi : 380 mm CCR 3 m 2.5 km MeO LLR Telescope T = 16.6 µs arge 7

8 Mini-DOLL ground ground link: Las resuls 1 CCR on he Calern hill@2.5 km One ccle/ms 1 mm Daa rae : 1 khz 1 ms Toal recorded poins Fracion of deleed poins min 8

9 Mini-DOLL ground ground link: Las resuls 2 Turbulence noise floor Mechanical Vibraions Frac. freq. Allan deviaion, σ τ 1E-12 1E-13 1E-14 1E km uncompensaed fibre link 1E Averaging ime, τ / s dominaed b amospheric urbulence below 10 Hz urbulence noise level ver similar o asronomical measuremens verical propagaion expec same order of magniude noise on saellie link similar noise level o uncompensaed 10 2 km fibres encouraging, bu differen dela imes compensaion schemes less efficien 9

10 10 d 4 u c v c v c v c v am s g s g d am g s g s u + + = + + = 2 /, d u Define iming observable: Imposing 2 3 : Dominan noise sources + + = 2 1, c v c v am am g g g s The noise on can hen be calculaed from he known noise on v g and am. measured on he uncompensaed ground link: T n n n g g + = T cos f S ft f S g π = Ground Saellie frequenc ransfer wih noise compensaion Clock frequenc difference

11 Ground Saellie frequenc ransfer wih noise compensaion: paricular example Geosaionar saellie T ms Calculae -+T 14 /2 from our ground ground link and look a is saisics: Frac. freq. Allan deviaion, σ τ Compensaed esimaion Uncompensaed measured Bes opical clocks Averaging ime, τ / s Challenges: Ccle slips scinillaion don compensae need o be idenified and removed Require sies wih low urbulence asronomical observaion sies Invesigae adapive opics schemes o miigae ccle slips 11

12 Conclusion and perspecives Operaion of a coheren opical links hrough he urbulen amosphere Mini-DOLL sep 1 The measured phase noise is dominaed b amospheric urbulence, bu ver promising for T/F applicaions In a compensaed wo-wa ground geosaionar saellie link, expec o reach performance of bes opical clocks in s inegraion ime Inerconinenal links a he same performance via geosaionar saellie are feasible, wih relaivel small and echnologicall unchallenging on board package Inerplanear links are more challenging power, AO bu feasible Mini-DOLL projec seps 2. and 3. should provide more reliable esimaes over he nex ears, in paricularl adverse condiions Doppler, power, Oher applicaions laser Doppler ranging, opical communicaions should also benefi from hese developmens 12

13 Thanks Albanesse Dominique OCA Bize Sébasien SYRTE Lours Michel SYRTE Sanarelli Giorgio SYRTE Torre Jean Marrie OCA CNES and PPF-GRAVITE Universié Paris VI for financing 13

14 Inerconinenal frequenc ransfer via geosaionar saellie wih noise compensaion common view Requiremens o reach performances a he same level as esimaes for he compensaed ground saellie link previous slide: free running, 1W, YAG laser on board heerodne deecion on board Two 10 cm elescopes on board, 40 cm elescopes on ground approx. 10 nw o µw a recepion poining a 2 14

15 Mini-DOLL ground-ground: Experimenal seup Couner /4 VCO φ lock BW = 0.1 o 100 khz Ampli. -30 dbm, 200 MHz Nd-YAG à1064 nm P 700 mw Laser Insolaor λ/2 Polariser λ/4 λ/4 Ι To Telescope 2x100 MHz AOM 2 W Ampli. DDS VCO: POS MHz, noise khz Sf = 4x10-31 /Hz@ opical frequenc, 10 4 Couper: no dead-ime 4 65 MHz, noise 1 1s Ampli.: ZX E+, 20 MHz 6 GHz, gain 15 db less hen amospheric noise 15

16 Inerconinenal frequenc ransfer via geosaionar saellie wih noise compensaion common view Requiremens o reach performances a he same level as esimaes for he compensaed ground saellie link previous slide: free running, 1W, YAG laser on board heerodne deecion on board Two 10 cm elescopes on board, 40 cm elescopes on ground approx. 10 nw o µw a recepion poining a 2 16

17 Applicaions 3: SAGAS Search for anomalous Graviaion using Aomic Sensors SAGAS specs. on one wa noise Acceleromeer Turbulence Turbulence conribuion should be OK! 17

18 Inerconinenal frequenc ransfer via geosaionar saellie wih noise compensaion common view Requiremens o reach performances a he same level as esimaes for he compensaed ground saellie link previous slide: free running, 1W, YAG laser on board heerodne deecion on board ime snchronizaion o < 1 µs can be srongl relaxed if laser is sabilized orbi deerminaion a he 300 m level can be srongl relaxed if laser is sabilized Two 10 cm elescopes on board, 40 cm elescopes on ground approx. 10 nw o µw a recepion poining a 2 18

19 The urbulence is defined as a flucuaion of a refracive indexdifference beween wo poins spaced b a disance R.

20 Applicaions 1: Saellie Laser Ranging SLR and Frequenc clocks comparison d 4 Doppler Amosphere u 2 20

21 Applicaions 2: Saellie Laser Ranging SLR and Frequenc Clocks Comparison =0 for 1 = 4 and 2 = 3?? measured?? Saellie Laser Ranging SLR =0 for 2 = 3 measured Frequenc clocks comparison Ex: GPS saellie for 1 = 4 and 2 = 3 Ex: geosaionar saelliet 23 = 2-3 =0 round-rip ime = 175 ms round-rip ime T 14 = 250 ms 21