SI23523A

SI23523A - Optical system for signal transfer of time reference

Info

Publication number: SI23523A
Application number: SI201000323A
Authority: SI
Inventors: MatjaĹľ VIDMAR; Jurij Tratnik; Leon PAVLOVIÄŚ; BoĹˇtjan Batagelj; PrimoĹľ LEMUT; Sebastjan Zorzut; ÄŚrt VALENTINÄŚIÄŚ
Original assignee: Instrumentation Technologies D.D.
Priority date: 2010-10-14
Filing date: 2010-10-14
Publication date: 2012-04-30

Abstract

The submitted invention is applied on optical system for signal transfer of time reference and radio-frequency synchronization of multiple events on more distant locations with femtosecond accuracy, for example inside of accelerator of elementary participles, where a synchronized scheme with low trembling of phase of signal and long-term stability, containing usual telecommunication single-mode optical fibre is required. The mentioned system contains a transmitter (1), oscillator (2) with low trembling and receiver (3), at which the mentioned transmitter (1) and receiver (3) are connected with transmitting optical line (4) and reverse optical line (5) and a compensation set(23).

Description

Optični sistem za prenos signala časovne referenceOptical time reference signal transmission system

Predloženi izum se nanaša na optični sistem za prenos signala časovne reference in radiofrekvenčno sinhronizacijo večkratnih dogodkov s femtosekundno natančnostjo na več oddaljenih lokacijah, kot na primer znotraj pospeševalnika osnovnih delcev, kjer se zahteva sinhronizacijsko shemo z nizkim drhtenjem faze signala in dolgoročno stabilnostjo, obsegajoč prenos po običajnem telekomunikacijskem enorodovnem optičnem vlaknu.The present invention relates to an optical system for transmitting a time reference signal and radio frequency synchronization of multiple events with femtosecond precision at multiple remote locations, such as within a particle accelerator, which requires a low phase shake synchronization scheme and long term stability comprising conventional telecommunications single-layer optical fiber.

Znane rešitve s tega področja uporabljajo kakovostne mikrovalovne oscilatorje s samo nekaj femtosekundnim drhtenjem faze v integracijskem področju odmika 10 Hz do 10 MHz od frekvence nosilca. Obstajajo pa tudi rešitve za časovno in radiofrekvenčno sinhronizacijo, ki za stabilizacijo optičnih vlakenskih povezav, ki prenaša referenčni časovni signal, uporabljajo interferometrično metodo in/ali rodovno vklenjen impulzni laserski vir.Known solutions in this field use high-quality microwave oscillators with only a few femtosecond phase shakes in the integration range of 10 Hz to 10 MHz away from the carrier frequency. There are also time and radio frequency synchronization solutions that use an interferometric method and / or a generic pulsed laser source to stabilize optical fiber links that transmit a reference time signal.

Uporabljeni laserski vir deluje pri valovni dolžini v področju 1550 nm. Optično vlakno ima pri tej valovni dolžini nizko slabljenje, veliko pasovno širino in odpornost na elektromagnetne motnje. Kljub temu pa je vlakno podvrženo spremembam fazne in skupinske hitrosti v odvisnosti od temperaturnih nihanj in je občutljivo na mehanske in/ali akustične motnje.The laser source used operates at a wavelength of 1550 nm. Optical fiber has low attenuation, high bandwidth and resistance to electromagnetic interference at this wavelength. Nevertheless, the fiber is subject to phase and group velocity changes as a function of temperature fluctuations and is sensitive to mechanical and / or acoustic disturbances.

Prva skupina sorodnih rešitev temelji na uporabi frekvenčnega odmika na tako imenovanem Michelsonovem interferometeru. Optični izvor je visoko koherenten laser v neprekinjenem načinu delovanja. Interferometrična metoda uspešno stabilizira optično fazo, vendar nikakor ne stabilizira skupinske hitrosti. Ker je skupinska hitrost optične povezave pomembna za radiofrekvenčno distribucijo signala, je zakasnitev implicitno obračunana po metodi odštevanja faze. Vendar pa ob zagonu sistema fazna stabilizacija ni zajamčena, saj se podatki o fazi izgubijo ob izklopu sistema. Ob vsakem začetku obratovanja prenosnega sistema je potrebno fazo radiofrekvenčnega signala ponovno nastaviti.The first group of related solutions is based on the use of frequency drift on the so-called Michelson interferometer. The optical source is a highly coherent laser in continuous mode. The interferometric method successfully stabilizes the optical phase but does not in any way stabilize the group velocity. Since the bandwidth of the optical link is important for the radio frequency distribution of the signal, the delay is implicitly calculated by the phase subtraction method. However, phase stabilization is not guaranteed at system startup, as phase data is lost when the system is switched off. Each time the transmission system is commissioned, the radio frequency phase must be reset.

Druga skupina rešitev uporablja glavni rodovno vklenjeni laser, ki z vklenitvijo na mikrovalovni oscilator z nizkim drhtenjem prenaša časovni signal v obliki impulznega vlaka io na več lokacij preko stabiliziranih vlakenskih povezav. Na vsaki oddaljeni lokaciji se nahajajo pomožni laserji, ki so vklenjeni na glavni laser in z mešanjem optičnih signalov ustvarjajo radiofrekvenčni signal. V tem primeru je kritična časovna stabilnost vlakenskih povezav, saj ni povratne vezave. Dolgoročna stabilnost ni dosežena.The second group of solutions uses the main generic-switched laser, which, by switching to a low-shake microwave oscillator, transmits a time signal in the form of a pulsed train io to several locations via stabilized fiber connections. At each remote location are assisted lasers that are connected to the main laser and generate a radio frequency signal by mixing optical signals. In this case, the stability of the fiber connections is critical, as there is no feedback. Long-term stability is not achieved.

Naloga izuma je ustvariti optični sistem za prenos signala časovne reference in radiofrekvenčno sinhronizacijo večkratnih dogodkov na več oddaljenih lokacijah s femtosekundno natančnostjo, pri katerem so odpravljene pomanjkljivosti znanih rešitev.It is an object of the invention to create an optical system for transmitting a time reference signal and radio frequency synchronization of multiple events at multiple remote locations with femtosecond precision, which eliminates the disadvantages of known solutions.

Zastavljena naloga je po izumu rešena s stabilizacijo vlakenskih povezav, ki prenašajo mikrovalovni takt z nizkim drhtenjem. Pri sistemu za radiofrekvenčno sinhronizacijo s femtosekundno natančnostjo več dogodkov na različno oddaljenih lokacijah, kot na primer pri pospeševalniku osnovnih delcev, s ciljem prenosa mikrovalovnega takta z nizkim drhtenjem se po izumu uporablja stabilizirano vlakensko povezavo. Omenjeno povezavo sestavlja par enorodovnih optičnih vlaken, ki omogoča kompenzacijo faznega premika sinhronizacijskega signala, oddajnik, kjer se spremembe faze demoduliranega povratnega signala v primerjavi s fazo vhodne reference uravnajo z valovno dolžino laserskega vira in sprejemnik, kjer se prvi del signala vrne do oddajnika, drugi del signala pa se očisti s pomočjo vztrajnika, npr. v fazno sklenjeni zanki z uporabo oscilatorja ali pasovno prepustnega frekvenčnega sita. Pri tem je omenjeni laserski vir moduliran z nizko drhtečim mikrovalovnim taktom, valovna dolžina omenjenega laserskega vira pa preko barvne disperzije vlakna vpliva na skupinsko zakasnitev signala.The object of the present invention is solved by stabilizing the fiber connections that transmit low-shake microwave clock. In the case of a radio frequency synchronization system with femtosecond precision, multiple events at different remote locations, such as in a particle accelerator, for the purpose of transmitting low-shake microwave clock, a stabilized fiber link is used according to the invention. Said connection consists of a pair of single-optical fibers that compensates for the phase shift of the synchronization signal, a transmitter where changes in the phase of the demodulated feedback signal are compared with the phase of the input reference by the wavelength of the laser source and the receiver, where the first part of the signal returns to the transmitter, the second and part of the signal is cleared by a flywheel, e.g. in a phase-locked loop using an oscillator or bandwidth. The said laser source is modulated by a low quivering microwave clock, and the wavelength of said laser source, through the color dispersion of the fiber, affects the collective delay of the signal.

Sistem po izumu torej obsega oddajnik, oscilator z nizkim drhtenjem, kompenzacijski sklop in sprejemnik, pri čemer sta omenjeni oddajnik in omenjeni sprejemnik povezana z oddajno linijo in povratno linijo. Pri tem sta omenjena oddajna linija in omenjena povratna linija vsakokrat zasnovani kot enorodovno optično vlakno. Omenjeni kompenzacijski sklop sestoji iz kompenzacijskega koluta optičnega vlakna in grelno-hladilnega elementa, s pomočjo katerega toplotno vplivamo na omenjeni kompenzacijski kolut. Nadalje je po izumu predvideno, da omenjeni oddajnik obsega prvo enoto, sestoječo iz prve polprevodniške fotodiode, faznega detektorja in faznega sukalnika, ki je povezana z laserskim elektrooptičnim modulatorjem, in drugo enoto, sestoječo iz druge polprevodniške fotodiode in faznega detektorja z regulatorjem.The system according to the invention therefore comprises a transmitter, a low oscillator oscillator, a compensation circuit and a receiver, said transmitter and said receiver being connected to a transmit line and a return line. In this case, said transmission line and said return line are each designed as a single-optical fiber. Said compensation assembly consists of a fiber optic compensation disk and a heating-cooling element by means of which the said compensation disk is thermally affected. It is further contemplated according to the invention that said transmitter comprises a first unit consisting of a first semiconductor photodiode, a phase detector and a phase switch connected to a laser electro-optical modulator, and a second unit consisting of a second semiconductor photodiode and a phase detector with a controller.

Po izumu je nadalje predvideno, da je omenjenemu regulatorju omenjene druge enote izbiroma prigrajen krmilnik, s pomočjo katerega se ločeno krmili delovno temperaturo omenjenega laserskega vira in omenjenega grelno-hladilnega elementa. Pri tem je omenjeni krmilnik zasnovan bodisi v obliki strojne ali programske opreme.According to the invention it is further provided that said controller of said second unit is optionally fitted with a controller by means of which the operating temperature of said laser source and said heating and cooling element are separately controlled. In doing so, said controller is designed either in the form of hardware or software.

Nadalje je po izumu predvideno, da omenjeni sprejemnik obsega tretjo polprevodniško fotodiodo in vztrajnik. Pri tem je omenjeni vztrajnik zasnovan bodisi kot fazno sklenjena zanka z uporabo oscilatorja ali kot pasovnoprepustno sito z visoko kvaliteto.It is further contemplated according to the invention that said receiver comprises a third semiconductor photodiode and a flywheel. The flywheel is designed either as a phase-locked loop using an oscillator or as a high-quality bandwidth.

Izum je v nadaljevanju podrobneje opisan na osnovi izvedbenega primera in s sklicevanjem na priloženo skico, kjer je shematsko prikazan sistem za optično razdeljevanje signala časovne reference in radiofrekvenčno sinhronizacijo večkratnih dogodkov po izumu.The invention will now be described in more detail based on an embodiment and with reference to the accompanying drawing, which schematically shows a system for the optical distribution of a time reference signal and the radio frequency synchronization of multiple events according to the invention.

Omenjeni optični sistem za prenos signala časovne reference po izumu sestoji iz oddajnika 1, ki se nahaja na lokaciji oscilatorja 2 z nizkim drhtenjem, in sprejemnika 3, ki se nahaja na oddaljeni lokaciji, pri čemer sta omenjeni oddajnik 1 in omenjeni sprejemnik 3 povezana z oddajno linijo 4 in povratno linijo 5, ki sta vsakokrat zasnovani iz vsaj enega enorodovnega optičnega vlakna. Uporaba dveh iz optičnega vlakna zasnovanih linij 4, 5 namesto ene same omogoča kompenzacijo premika faze sinhronizacij skega signala. Tako za oddajno linijo 4 kot tudi povratno linijo 5 se predvideva, da je polarizacijska rodovna disperzija prednostno enako ali manj kot 0,02 ps/Jkm. Pri tem privzamemo, da sta iz optičnih vlaken zasnovani liniji 4, 5 enakovrstni, izjemoma se lahko razlikujeta v svoji polarizacijski rodovni disperziji. S tem, da se v praksi optična vlakna vsakokraten linije 4, 5 položi neposredno drugega ob drugem, se izenači zunanje vplive, kot na primer sprememba dolžine optične poti zaradi vpliva temperature, na omenjena optična vlakna.Said optical time reference signal transmission system according to the invention consists of a transmitter 1 located at the location of a low-shake oscillator 2 and a receiver 3 located at a remote location, said transmitter 1 and said receiver 3 being connected to a transmitter line 4 and return line 5, each of which is designed from at least one mono-optical fiber. The use of two fiber optic lines 4, 5 instead of a single one allows compensation for the phase shift of the synchronization signal. For both transmission line 4 and return line 5, the polarization generic dispersion is assumed to be preferably equal to or less than 0.02 ps / Jkm. In doing so, we assume that the fiber-optic lines 4, 5 are of the same type, exceptionally different in their polarization kinetic dispersion. By putting optical fibers in line 4, 5 in each case directly next to each other, external influences, such as changes in the optical path length due to the influence of temperature, on said optical fibers are equalized.

Vir optičnega signala v oddajniku 1 je splošno znan lasersko-modulatorski sklop 10, prednostno je to DFB (angl. distributed feed back) laserski vir, ki se uporablja za zelo hitre telekomunikacijske zveze. Omenjeni sklop 10 je lahko zasnovan kot enovit sklop ali pa je izbiroma zasnovan iz ločenega laserskega vira 21 in elektro-optičnega modulatorja 22.The optical signal source in transmitter 1 is a commonly known laser modulator assembly 10, preferably a distributed feed back (DFB) laser source used for very fast telecommunication links. Said assembly 10 may be designed as a single assembly or optionally designed from a separate laser source 21 and an electro-optical modulator 22.

Oddajnik 1 je sestavljen iz dveh glavnih enot. Prva enota 6, ki sestoji iz prve polprevodniške fotodiode 7, faznega detektorja 8 in faznega sukalnika 9, je povezana z omenjenim laserskomodulatorskim sklopom 10. Naloga omenjene prve enote 6 je kompenzacija odstopanj faze vhodnega (električnega) radiofrekvenčnega signala Sl, ki se ga dovaja iz omenjenega io oscilatorja 2 z nizkim drhtenjem, znotraj omenjenega lasersko-modulatorskega sklopa 10. V primeru izvedbe z ločenim laserskim virom 21 in elektro-optičnim modulatorjem 22 je po izumu predvideno, da je omenjeni modulator 22 LiNbO3 ali InP modulator. Omenjeni sklop oddaja optični signal S2, katerega delni signal S3 se na vlakenskemu delilniku 11 odcepi in vodi v popravljalno zanko, ki jo sestavljajo omenjena polprevodniška fotodioda 7, omenjeni fazni detektor 8 in omenjeni fazni sukalnik 9. Na ta način se meri fazno neusklajenost med vhodnim električnim signalom Sl iz glavnega oscilatorja 2 in optičnim signalom S3 iz delilnika 11 ter se nastavi fazni premik. S tem je faza izhodnega optičnega signala S4, ki izstopa iz omenjenega delilnika 11, vedno usklajena z vhodnim električnim signalom Sl iz oscilatorja 2.Transmitter 1 consists of two main units. The first unit 6, consisting of a first semiconductor photodiode 7, a phase detector 8 and a phase switch 9, is connected to said laser modulator assembly 10. The function of said first unit 6 is to compensate for phase deviations of the input (electrical) radio frequency signal Sl supplied from said io low oscillator 2 oscillator 2 within said laser modulator assembly 10. In the case of a separate laser source 21 and an electro-optical modulator 22, it is contemplated according to the invention that said modulator 22 is a LiNbO3 or InP modulator. Said assembly transmits an optical signal S2 whose partial signal S3 is cleaved at the fiber divider 11 and leads to a repair loop consisting of said semiconductor photodiode 7, said phase detector 8, and said phase switch 9. In this way, a phase mismatch between the input is measured the electrical signal Sl from the main oscillator 2 and the optical signal S3 from the divider 11 and adjust the phase shift. Thereby, the phase of the optical output signal S4 exiting said divider 11 is always aligned with the input electrical signal Sl of oscillator 2.

Druga enota 12 oddajnika 1, ki sestoji iz druge polprevodniške fotodiode 13 in faznega detektorja z regulatorjem 14, sprejema optični signal S5 iz omenjene povratne optične linije 5, ki se od izhodnega optičnega signala S4 iz oddajne optične linije 4 loči v delilniku 15. Fazo omenjenega povratnega optičnega signala S5 se primerja s fazo vhodnega električnega signala Sl. Vsakršna sprememba razlike faz se s pomočjo faznega detektorja z regulatorjem 14 izravna s povratnim signalom S8, ki spremeni valovno dolžino omenjenega laserskega vira 10. Z valovno dolžino omenjenega laserskega vira 10 nastavljamo skupinsko zakasnitev vsakokratnega optičnega signala S2 ter s tem S4 in S5 optičnih vlaken s pomočjo barvne disperzije vsakokratnega optičnega vlakna, ki predstavlja oddajno linijo 4 in povratno linijoThe second unit 12 of transmitter 1, consisting of a second semiconductor photodiode 13 and a phase detector with a controller 14, receives an optical signal S5 from said feedback optical line 5, which is separated from the output optical signal S4 from the transmitting optical line 4 by the phase divider 15. the reverse optical signal S5 is compared with the phase of the electrical input signal FIG. Any change in phase difference is compensated by a phase detector with regulator 14 with a feedback signal S8, which changes the wavelength of said laser source 10. The wavelength of said laser source 10 sets the collective delay of the respective optical signal S2 and thus S4 and S5 of the optical fibers with by means of the color dispersion of each optical fiber representing the transmission line 4 and the return line

5.5.

V sprejemniku 3 sistema po izumu se delni signal S6 vhodnega signala S4, ki potuje iz lasersko-modulatorskega sklopa 10 in se na omenjenem delilniku 15 loči od povratnega optičnega signala S5, posreduje v tretjo polprevodniško fotodiodo 16, medtem ko se povratni optični signal S5 pošlje po povratni liniji 5 nazaj v drugo enoto 12 oddajnika 1. V sprejemniku 3 se sprejeti signal S6 na omenjeni fotodiodi 16 bodisi demodulira in ojača bodisi demodulira in oslabi na nivo, ki omogoča fazno primerjavo.In the receiver 3 of the system according to the invention, the partial signal S6 of the input signal S4 traveling from the laser modulator assembly 10 and separated from the return optical signal S5 at said divider 15 is transmitted to the third semiconductor photodiode 16, while the return optical signal S5 is sent after return line 5 back to the second unit 12 of transmitter 1. In receiver 3, the received signal S6 on said photodiode 16 is either demodulated and amplified or demodulated and attenuated to a level that allows for phase comparison.

V konkretnem izvedbenem primeru je v sprejemniku 3 na oddaljeni lokaciji uporabljena direktna detekcija optičnega signala S6. Omenjeni vztrajnik 17 je po izumu zasnovan bodisi kot fazno sklenjena zanka z uporabo oscilatorja ali pa kot pasovnoprepustno sito z visoko kvaliteto.In the specific embodiment, direct receiver optical detection S6 is used in receiver 3 at a remote location. Said flywheel 17 is designed according to the invention either as a phase-locked loop using an oscillator or as a high-quality bandwidth sieve.

Razmerje signal/šum na izhodu iz omenjene fotodiode 16 znaša okoli 60 dB in je neprimerno za uporabo ali za nadaljnjo distribucijo. V ta namen se iz omenjene fotodiode 16 izstopajoči izhodni signal očisti v vztrajniku 17. Pasovna širina omenjene zanke mora biti ozka, zato da se zmanjša fazni šum.The signal-to-noise ratio at the output of said photodiode 16 is about 60 dB and is unsuitable for use or for further distribution. For this purpose, the output signal from said photodiode 16 is cleared in the flywheel 17. The bandwidth of said loop must be narrow in order to reduce phase noise.

Termični premik v sistemu po izumu uporabljenih polprevodniških fotodiod 7, 13, 16, ki imajo prednostno enake lastnosti, faznega detektorja 8, faznega detektorja z regulatorjem 14 in vztrajnika 17 se izloči s temperaturno nadzorovanim okoljem. Oddajnik in sprejemnik se vzdržuje pri enaki temperaturi. Le-to zagotavlja, da se enake komponente enako odzivajo na različnih lokacijah, tako v oddajniku 1 kot v sprejemniku 3. Temperaturno stabilne komore znižujejo termični premik, kar omogoča dolgoročno stabilnost.The thermal displacement of the semiconductor photodiodes 7, 13, 16 having the same properties, preferably of the same nature, of the phase detector 8, phase detector with regulator 14 and flywheel 17 is eliminated by the temperature controlled environment. The transmitter and receiver are maintained at the same temperature. This ensures that the same components respond equally to different locations, both in transmitter 1 and receiver 3. Temperature-stable chambers reduce thermal displacement, which allows for long-term stability.

Sistem po izumu deluje kot sledi. Iz laserskega vira 10 izhajajoči optični signal S2, se na delilniku 11 loči na optični signal S4, ki se ga vodi v sprejemnik 3 na oddaljeni lokaciji, in na optični signal S3, ki se ga vodi v prvo polprevodniško fotodiodo 7, kjer se ga pretvori v električni signal. Iz omenjene fotodiode 7, se omenjeni električni signal vodi v fazni detektor 8, kjer se fazo omenjenega električnega signala primerja s fazo iz oscilatorja 2 izhajajočega električnega signala Sl. Zatem se takšen, iz faznega detektorja 8 izstopajoči korekcijski električni signal vodi v fazni sukalnik 9, kjer se njegovo fazo uskladi s fazo omenjenega električnega signala Sl iz oscilatorja 2. Tako korigiran in fazno usklajen električni signal se vodi dalje v laserski vir 10, kjer ustrezno korigira iz omenjenega vira izstopajoči optični signal S2.The system according to the invention functions as follows. The optical signal S2 emanating from the laser source 10 is separated at the divider 11 into an optical signal S4, which is directed to the receiver 3 at a remote location, and an optical signal S3, which is led to the first semiconductor photodiode 7, where it is converted into an electrical signal. From said photodiode 7, said electrical signal is guided to a phase detector 8, where the phase of said electrical signal is compared with that of the output electric signal FIG. Thereafter, such a correcting electrical signal from phase detector 8 is guided to a phase switch 9, where its phase is aligned with the phase of said electric signal Sl from oscillator 2. The corrected and phase-coordinated electrical signal is then directed to the laser source 10, where appropriate corrects the outgoing optical signal S2 from said source.

Kot omenjeno se korigirani optični signal S2 na omenjenem delilniku 11 razdeli na omenjeni optični signal S3 in optični signal S4, ki se ga vodi v oddaljeni sprejemnik 3. Na delilniku 15 se omenjeni optični signal S4 razdeli na povratni optični signal S5 in optični signal S6. Omenjeni povratni optični signal S5 se vodi nazaj v drugo polprevodniško foto diodo 13 oddajnika 1, kjer se ga pretvori v električni signal, od tam pa v fazni detektor z regulatorjem 14, kjer se ga ustrezno obdela in primerja z vhodnim električnim signalom Sl iz oscilatorja 2. Tako obdelan korekcijski električni signal S8 se vodi v omenjeni laserski vir 10, kjer nastavi valovno dolžino izhodne svetlobe signala S2.As mentioned, the corrected optical signal S2 at said divider 11 is divided into said optical signal S3 and an optical signal S4 that is directed to a remote receiver 3. At divider 15, said optical signal S4 is divided into a return optical signal S5 and an optical signal S6. Said feedback optical signal S5 is fed back to the second semiconductor photo diode 13 of transmitter 1, where it is converted into an electrical signal, and from there to a phase detector with controller 14, where it is properly processed and compared with the electrical input signal Sl of oscillator 2 The correction electrical signal S8 thus treated is guided to said laser source 10 where it adjusts the wavelength of the light output of signal S2.

Omenjeni optični signal S6, ki izstopa iz omenjenega delilnika 15 in se ga vodi dalje v tretjo polprevodniško foto diodo 16 v sprejemniku 3, kjer se pretvori v električni signal, le tega se vodi v omenjeni vztrajnik 17, kjer se ga očisti šumov in podobno. Del iz vztrajnika 17 izstopajočega električnega signala S7 se v obliki povratne zanke vrne v vztrajnik, kjer po potrebi korigira omenjeni izstopajoči električni signal S7.Said optical signal S6 exiting said divider 15 and further fed to a third semiconductor photo diode 16 in receiver 3, where it is converted to an electrical signal, which is then guided to said flywheel 17, where it is cleared of noise and the like. The portion from the flywheel 17 of the output electrical signal S7 is returned in the form of a feedback loop to the flywheel, where necessary, where necessary, it corrects the output electrical signal S7.

Za dodatno izboljšanje kvalitete omenjenega optičnega signala S4 oz. za dodatno kompenzacijo spremembe dolžine optične poti na prenosni poti je po izumu nadalje predvideno, da je med omenjenim oddajnikom 1 in omenjenim sprejemnikom 3 razporejen kompenzacijski sklop 23, ki sestoji iz kompenzacijskega koluta 24 iz optičnega vlakna in grelno-hladilnega elementa 25, s pomočjo katerega toplotno vplivamo na omenjeni kompenzacijski kolut 24. Pri tem je po predloženem izumu predvideno, da je omenjeni kompenzacijski sklop 23 bodisi del oddajnika 1 bodisi del sprejemnika 3 bodisi predstavlja samostojno enoto. S pomočjo omenjenega kompenzacijskega sklopa 23 torej bodisi grejemo ali hladimo odsek omenjene oddajne linije 4 in odsek omenjene povratne linije 5, s čimer se kompenzira spremembo dolžine optične prenosne poti. Kompenzacija s pomočjo omenjenega koluta 24 je komplementarna poprej opisani primarni kompenzaciji. Navedena dodatna kompenzacijska metoda ima nalogo kompenzirati dolgotrajne (počasne) vplive okolja na optično pot, kot so na primer temperaturne spremembe dan-noč, medtem ko primarna kompenzacijska metoda zagotavlja kompenzacijo hitrejših vplivov na optično pot, kot so na primer vklop-izklop klimatskih naprav (histereza, mrtvi hod, segrevanje zaradi obsijanosti s sončno svetlobo in podobno).To further improve the quality of said optical signal S4 or. to further compensate for the variation of the optical path length in the transmission path according to the invention, it is further provided that a compensation assembly 23 is provided between said transmitter 1 and said receiver 3, consisting of a fiber optic compensation circuit 24 and a heating-cooling element 25, by means of which it is said that the compensation circuit 23 is either part of transmitter 1 or part of receiver 3 or represents a standalone unit. By means of said compensation circuit 23, therefore, either the section of said transmission line 4 and the section of said return line 5 are heated or cooled, thereby compensating for the change in the length of the optical transmission path. Compensation by means of said reel 24 is complementary to the primary compensation previously described. This additional compensation method is intended to compensate for long-term (slow) environmental influences on the optical path, such as day-night temperature changes, while the primary compensation method compensates for faster effects on the optical path, such as on / off air conditioners ( hysteresis, deadlock, heat from sunlight and the like).

Omenjeno kompenzacijo se po predloženem izumu doseže s tem, da se izkoristi sam moteči pojav v vsakokratnem optičnem vlaknu, pri čemer uporabimo učinek omenjenega pojava ravno v nasprotni smeri. Če se na primer optično vlakno omenjene oddajne linije 4 in/ali omenjene povratne linije 5 na prenosni poti podaljša zaradi povišanja okoliške temperature, se s pomočjo grelno-hladilnega elementa 25 aktivira hlajenje kompenzacijskega koluta 24, s čimer se ohrani enako skupno dolžino optične poti. Na tak način se območje regulacije poveča tudi do 10-krat.Said compensation according to the present invention is achieved by taking advantage of the interfering phenomenon itself in the respective optical fiber, using the effect of said phenomenon in the opposite direction. For example, if the optical fiber of said transmission line 4 and / or said return line 5 extends in the transmission path due to an increase in ambient temperature, cooling of the compensation disc 24 is activated by the heating-cooling element 25, maintaining the same overall length of the optical path. In this way, the regulation area is increased up to 10 times.

Omenjenemu regulatorju 14 omenjene druge enote 12 omenjenega oddajnika 1 je izbiroma prigrajen krmilnik 14’, s pomočjo katerega se ločeno krmili delovno temperaturo omenjenega laserskega vira 21 in omenjenega grelno-hladilnega elementa 25. Omenjeni krmilnik 14' je po izumu lahko zasnovan v obliki strojne ali programske opreme.Said controller 14 of said second unit 12 of said transmitter 1 is optionally fitted with a controller 14 'by means of which the operating temperature of said laser source 21 and said heating and cooling element 25 are separately controlled. Said controller 14' can be designed in the form of a machine or software.

Opisana dodatna kompenzacijska metoda omogoča, da je temperatura laserskega vira 21 vedno v bližnji okolici nastavljene delovne točke (na primer na sredini delovnega temperaturnega območja laserskega vira) s čimer se po eni strani zmanjšajo stranski elektrooptični pojavi v delovanju laserja in modulatorja, kar poveča natančnost kompenzacije naprave, po drugi strani pa se zaradi bistveno zmanjšanega hoda delovne temperature laserja in posledično manjšega utrujanja materialov poveča življenjska doba omenjenega laserja.The additional compensation method described allows the laser source temperature 21 to always be in the vicinity of a set point (for example, in the middle of the laser source operating temperature range), thereby reducing lateral electro-optical phenomena in the operation of the laser and the modulator, which increases the accuracy of the compensation devices, on the other hand, due to the significantly reduced stroke temperature of the laser and consequently less fatigue of the materials, increases the lifetime of said laser.

Opisani izum je mogoče uporabiti v napravi, kjer se uporablja ločeno oddajno linijo 4 in povratno linijo 5, kakor tudi v primeru, ko se tako za oddajni kot tudi za povratni signal uporabi eno samo vlakno. V primeru uporabe dveh vlaken je potrebno zagotoviti čim boljšo skladnost le-teh (dolžina in izenačen vpliv temperature na obe vlakni) znotraj omenjenega kompenzacijskega koluta.The present invention can be used in a device using a separate transmitter line 4 and a return line 5, as well as when a single fiber is used for both the transmitter and the return signal. If two fibers are used, it is necessary to ensure that they are as consistent as possible (length and uniform influence of temperature on both fibers) within the said compensation roll.

Gretje in hlajenje kompenzacijskega koluta 24 po izumu z grelno/hladilnim elementom 25 je v konkretnem izvedbenem primeru zasnovano s pomočjo termoelektričnih členov, lahko pa se uporabi poljuben drug fizikalni princip gretja in hlajenja.The heating and cooling of the compensating disc 24 according to the invention with the heating / cooling element 25 is in the specific embodiment designed by means of thermoelectric members, but any other physical principle of heating and cooling can be used.

Omenjeni kompenzacijski kolut 24 je lahko razporejen bodisi v oddajniku 1 ali sprejemniku 3, pri čemer je v slednjem primeru potrebna še dodatna komunikacija med oddajnikom in sprejemnikom.Said compensation disc 24 may be arranged in either transmitter 1 or receiver 3, in which case additional communication between the transmitter and the receiver is required.

Delovanje omenjenega krmilnika 14' je neposredno odvisno od razmerja dolžine optične poti znotraj kompenzacijskega koluta 24 in optične poti na prenosni poti (liniji 4 in 5). To razmerje določa odprtozančno ojačanje sistema. Da je sistem stabilen morajo biti parametri omenjenega krmilnika 14' določeni glede na odprtozančno ojačanje sistema, pri čemer se da te parametre določiti avtomatsko. Naprava izmeri delovne parametre (predvsem temperaturo laserja) pri fiksni temperaturi kompenzacijskega koluta 24. Po majhni spremembi temperature koluta 24, odzivu le-tega na zahtevo po spremenjeni temperaturi in ponovni meritvi parametrov, naprava sama izračuna potrebne parametre omenjenega krmilnika 14' in jih posreduje laserskemu viru 21 in/ali grelno-hladilnemu elementu 25.The operation of said controller 14 'is directly dependent on the ratio of the optical path length within the compensation reel 24 and the optical path in the transmission path (lines 4 and 5). This ratio determines the open-loop gain of the system. In order for the system to be stable, the parameters of said controller 14 'must be determined with respect to the open-loop amplification of the system, and these parameters can be determined automatically. The device measures the operating parameters (especially the laser temperature) at a fixed temperature of the compensation roll 24. After a small change in the temperature of the roll 24, the response thereof to the request for a changed temperature and the measurement parameters again, the device itself calculates the required parameters of said controller 14 'and transmits them to the laser source 21 and / or heating and cooling element 25.

Claims

1. Optical time reference signal transmission system and radio frequency synchronization of multiple events at multiple remote locations with femtosecond accuracy, at

5 is an example within a particle accelerator, which requires a low-phase-phase synchronization scheme and long-term stability, comprising a conventional telecommunications single-fiber optical fiber, characterized in that it comprises a transmitter (l), a low-shake oscillator (2), and a receiver (3 ), said transmitter (l) and said transceiver (3) being connected to the transmit optical line io (4) and the return optical line (5), and the compensation circuit (23).

System according to claim 1, characterized in that said transmit line (4) and said return line (5) are each formed of at least one single-optical fiber.

System according to claims 1 and 2, characterized in that said transmitter (1) comprises a first unit (6) consisting of a semiconductor photodiode (7), a phase detector (8) and a phase switch (9) connected to a laser electro-optical modulator (10), and a second unit (12) consisting of a semiconductor photodiode (13) and a phase detector with

20 with a regulator (14).

System according to Claims 1 and 2, characterized in that said compensation assembly (23) consists of an optical fiber compensating disc (24) and a heating-cooling element (25)

System according to claims 1 and 2, characterized in that said receiver (3) comprises a semiconductor photodiode (16) and a flywheel (17).

System according to claim 5, characterized in that said flywheel (17) is designed as an angle

30 phase-locked loop using an oscillator.

System according to claim 5, characterized in that said flywheel (17) is designed as a high-quality bandwidth sieve.

• ·

System according to any one of the preceding claims, characterized in that said controller (14) of said second unit (12) of said transmitter (l) is optionally fitted with a controller (14 ') by which the operating temperature of said laser source is separately controlled (21) and the said heating and cooling element (25).

System according to claim 8, characterized in that said controller (14 ') is designed in the form of hardware or software.