Lali-Dastjerdi, Zohreh

Denne afhandling fokuserer på fiber optiske parametriske forstærkere samt regeneration i højhastigheds optiske kommunikations systemer. Fiber optiske parametriske forstærkere (FOPA) kan benyttes til adskillige applikationer baseret på hvorledes de implementeres i et optisk kommunikations system. Med afsæt i femto sekund forstærkningsresponsen samt deres _eksible spektrale operationsområde, kan FOPAer benyttes samtidigt både som forstærkere samt som optiske signal processorer i højhastigheds Tbaud netværk. I denne afhandling vil vi studere ydelsen af FOPAer i detaljer, både i det lineære samt i det ikke-lineære mættede område hvor de benyttes som rent optiske regeneratorer. Den optiske forstærkning samt amplitude regenererings egenskaberne af FOPAer bliver undersøgt for monokromatiske bølger, korte optiske pulser samt data modulerede signaler op til 640 Gbit/s. I det grundlæggende teoristudie i denne afhandling vil en ny fysisk forklaring af den observerede forskel i det mættede forstærkningsspektrums opførsel for en enkelt-pumpe FOPA blive præsenteret samt sammenlignet med den konventionelle fasetilpasnings beskrivelse. Den foreslåede teori kan forklare årsagen til asymmetrien i forstærkningsprofilen for enkelt-pumpe FOPAer som et sammenspil mellem tredje ordens dispersion samt udstråling af dispersive bølger i det mættede område. Desuden kan teorien benyttes til at forudsige styrken af asymmetrien i forstærkningen i den mættede enkelt-pumpe FOPA.Overførslen af intensitetsstøj fra pumpe til signal er blevet identificeret som en af de vigtigste støj bidragsydere i en FOPA idet det medfører modulation af signal forstærkningen. Overførslen af intensitetsstøj fra pumpe til signal er fastlagt i detaljer som funktion af modulation frekvens samt mætningseffekter for at afdække degraderingen af det forstærkede signal. I særdeles god overensstemmelse med de udførte eksperimenter er det eftervist at støjoverførslen til signalet kan undertrykkes ved at operere i det mættede område.I dette studie bliver forstærkningen af korte pikosekund samt endnu kortere optiske pulser undersøgt ved at benytte chirped-puls forstærkningsprincippet i FOPAer. Dynamikken af princippet samt pulsforvrængningen bliver studeret for forskellige chirped pikosekund pulser i overgangen fra det lineære til det ikkeline ære område. Forstærkningen af korte pulser kompatible med Tbaud systemer er eksperimentelt eftervist for første gang idet 400 fs pulser er blevet forstærket i en enkelt-pumpe FOPA.Endelig vil den første eksperimentelle demonstration af FOPA ydelsen i lang distance transmissions forbindelser så vel som i høj-kapacitets systemer blive præsenteret i den sidste del af denne afhandling. FOPAer er kaskadekoblet som inline forstærkere ved hjælp af en recirkulerende transmissionsløkke og fejlfri transmission ved 40 Gbit/s er succesfuldt demonstreret. Yderligere er fejlfri parametrisk forstærkning for højhastigheds seriel data på en enkelt bølgelængde blevet demonstreret for et optisk tids sammenflettet signal ved 640 Gbit/s uden nogen forøgelse i den nødvendig modtagne optisk effekt. Til sidst er en rent optisk fase bevarende amplitude regenerering baseret på en mættet FOPA ved 640 Gbit/s fase moduleret signal demonstreret.The present thesis is concerned with fiber optical parametric amplification and regeneration for high-speed optical communication systems. Fiber optical parametric amplifiers (FOPAs) have multi-functional applications depending on their implementation in optical systems. Based on a few femtosecond amplification response time and flexible operation spectral range, FOPAs are able to simultaneously operate as amplifiers and all-optical signal processors in high-speed Tbaud networks. In this thesis, we study the performance of FOPAs in detail in the linear and nonlinear (saturated) regimes where they can be utilized as all-optical regenerators. The optical gain and amplitude regeneration properties of FOPAs are investigated for monochromatic waves, short optical pulses and data modulated signals up to 640 Gbit/s.In the fundamental study part of the thesis, an original physical explanation behind an observed asymmetry in gain saturated single-pump FOPAs is presented. The proposed theory is able to explain the origin of gain asymmetries in singlepump FOPAs based on the interplay between third-order dispersion and radiation of dispersive waves in the saturation regime. Furthermore, it predicts the strength of the asymmetric gain in saturated single-pump FOPAs. Pump-to-signal intensity noise transfer has been recognized as one of the major noise sources in FOPAs as it leads to modulation of the signal gain. The conversion of intensity noise from pump to signal is quantified in detail in terms of modulation frequency and saturation effect in order to assess the degradation of the amplified signal. In a very good agreement with the performed experiments, it is shown that the noise transferred to the signal can be effectively suppressed by operating in the saturation regime.The amplification of short few picosecond and subpicosecond optical pulses is explored using the chirped-pulse ampli_cation scheme in FOPAs. The dynamics of the chirped-pulse amplification and pulse distortion are studied for differently chirped few-picosecond pulses in transition between the linear and the nonlinear regime. Amplification of short pulses compatible with Tbaud systems is experimentally carried out for the first time where 400 fs pulses are amplified in a single-pump FOPA.Finally, the first experimental demonstrations of the performance of FOPAs both in long transmission links as well as in high-capacity systems are presented in the last part of this thesis. FOPAs are cascaded as in-line amplifiers using a recirculating loop transmission and error-free transmission of 40 Gbit/s is successfully achieved. On the other hand, error-free parametric amplification for high serial data rates on a single-wavelength channel is demonstrated for an optical time division multiplexed signal at 640 Gbit/s with no power penalty. At last, all-optical phase-preserving amplitude regeneration based on a saturated-FOPA at 640 Gbit/s is demonstrated for phase modulated signals

Online Research Database In Technology

Optical Amplication for Terabit-per-Second Ultra-High Speed Communication Systems -DTU Orbit (09/11/2017) Optical Amplication for Terabit-per-Second Ultra-High Speed Communication SystemsThe present thesis is concerned with fiber optical parametric amplification and regeneration for high-speed opticalcommunication systems. Fiber optical parametric amplifiers (FOPAs) have multi-functional applications depending on theirimplementation in optical systems. Based on a few femtosecond amplification response time and flexible operationspectral range, FOPAs are able to simultaneously operate as amplifiers and all-optical signal processors in high-speedTbaud networks. In this thesis, we study the performance of FOPAs in detail in the linear and nonlinear (saturated)regimes where they can be utilized as all-optical regenerators. The optical gain and amplitude regeneration properties ofFOPAs are investigated for monochromatic waves, short optical pulses and data modulated signals up to 640 Gbit/s.  In the fundamental study part of the thesis, an original physical explanation behind an observed asymmetry in gainsaturated single-pump FOPAs is presented. The proposed theory is able to explain the origin of gain asymmetries insinglepump FOPAs based on the interplay between third-order dispersion and radiation of dispersive waves in thesaturation regime. Furthermore, it predicts the strength of the asymmetric gain in saturated single-pump FOPAs. Pump-to-signal intensity noise transfer has been recognized as one of the major noise sources in FOPAs as it leads to modulationof the signal gain. The conversion of intensity noise from pump to signal is quantified in detail in terms of modulationfrequency and saturation effect in order to assess the degradation of the amplified signal. In a very good agreement withthe performed experiments, it is shown that the noise transferred to the signal can be effectively suppressed by operatingin the saturation regime.  The amplification of short few picosecond and subpicosecond optical pulses is explored using the chirped-pulseampli_cation scheme in FOPAs. The dynamics of the chirped-pulse amplification and pulse distortion are studied fordifferently chirped few-picosecond pulses in transition between the linear and the nonlinear regime. Amplification of shortpulses compatible with Tbaud systems is experimentally carried out for the first time where 400 fs pulses are amplified in asingle-pump FOPA.  Finally, the first experimental demonstrations of the performance of FOPAs both in long transmission links as well as inhigh-capacity systems are presented in the last part of this thesis. FOPAs are cascaded as in-line amplifiers using arecirculating loop transmission and error-free transmission of 40 Gbit/s is successfully achieved. On the other hand, error-free parametric amplification for high serial data rates on a single-wavelength channel is demonstrated for an optical timedivision multiplexed signal at 640 Gbit/s with no power penalty. At last, all-optical phase-preserving amplitude regenerationbased on a saturated-FOPA at 640 Gbit/s is demonstrated for phase modulated signals. General informationState: PublishedOrganisations: Department of Photonics Engineering, High-Speed Optical Communication, Fiber Optics, Devices andNon-linear EffectsAuthors: Lali-Dastjerdi, Z. (Intern), Peucheret, C. (Intern), Rottwitt, K. (Intern), Galili, M. (Intern)Number of pages: 126Publication date: 2013 Publication informationPlace of publication: Kgs. LyngbyPublisher: Technical University of Denmark (DTU)Original language: EnglishMain Research Area: Technical/natural sciencesElectronic versions: Thesis_Zohreh_LaiDastjerdi.pdf Publication: Research › Ph.D. thesis – Annual report year: 2013 

Optical Amplication for Terabit-per-Second Ultra-High Speed Communication Systems

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Optical Amplication for Terabit-per-Second Ultra-High Speed Communication Systems

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