1,720,979 research outputs found
Optiskais Kerra efekts telekomunikāciju šķiedru mērījumos un signālu atjaunošanā
No full textLielas ātrdarbības šķiedru optiskās pārraides sistēmu attīstība galvenokārt ir notikusi pateicoties mazu zudumu kvarca stikla šķiedrām, optiskajiem pastiprinātājiem, kā arī viļņgarumdales blīvēšanas sistēmām. Tomēr vienlaicīga daudzkanālu pārraide un optiskā signāla pastiprināšana palielina pārraidāmā optiskā signāla jaudu. Līdz ar to daudz izteiktāk sāk izpausties optisko šķiedru nelineārās īpašības, kas izraisa dažādus nevēlamus signālu kropļojumus un pasliktina pārraides sistēmas darbību. Turklāt šķiedru nelinearitāte ir saistīta ne tikai ar tās traucējošo iedarbību signālu pārraidē, bet arī jaunām iespējam optisko signālu apstrādē. Tādēļ būtiski ir ņemt vērā ne tikai optiskās šķiedras vājinājumu un dispersiju, bet arī tās nelinearitāti raksturojošo parametru – nelineāro koeficientu.
Promocijas darbā veikts pētījums par telekomunikāciju optisko šķiedru efektīvā laukuma un nelineārā koeficienta novērtēšanas metodēm, kā arī sekmīgi realizēta šķiedras nelinearitātes pielietošana signālu atjaunošanā pilnīgi optiskajā apgabalā. Rezultātā promocijas darbā atspoguļoti pabeigtu pētījumu rezultāti, kas ļauj novērtēt no kvarca stikla izgatavotu optisko šķiedru nelinearitāti un tās pielietojuma iespējas optisko reģeneratoru izveidē
Optisko šķiedru nelineārā koeficienta noteikšanas metodes
No full textOptiskajām šķiedrām, kuras tiek izmantotas šķiedru optikas pārraides sistēmās, nepiemīt izteiktas nelineārās īpašības, taču nelineārās parādības var novērot pie lielām gaismas intensitātēm un lieliem pārraides attālumiem
Pump and Filtering Optimization in Mamyshev Regenerator
No full textIn this paper we present results from the study of optical signal regeneration using Mamyshev type regenerator. We have performed the simulations and experimental characterization of regenerator by obtaining it`s transfer function and output optical signal to noise ratio measurements for two different filters - fixed and a tunable optical filter. Investigated regenerator setup consists of a high power erbium doped fiber amplifier, highly nonlinear fiber and a single stage optical filtering. Signal used for regeneration was an on-off keying return to zero code 40 Gbps pulse sequence. To find out optimum filter pass-band shift from signal`s central wavelength the regenerator`s transfer function was measured. Results show that highest output signal to noise ratio improvement for the fixed filter is at 0.6nm shift and amplifier output power set to 63 mW. While the tunable filter shift is 0.7nm at the 100 mW power level
Research of Optical Radiation Intensity in Erbium Doped Optical Fibers
No full textAbstract – Optical amplifier usage in the fiber optics transamission systems significantly improves the transmission distance. But it also influence the signal quality. This article describes a study on optical intensity characteristics and its impact to optical signal propagation in the erbium doped fiber (EDF) used in the doped fiber amplifiers. First of all the far field optical power distribution measurements are performed at the output of Er3+ doped fiber using transverse shift measurement method. Based on the experimental results, the fiber effective area Aeff has been calculated. Following from the effective area results comparative analysis and estimation of the optical intensity results is given for EDF at different wavelengths. It was found that in the wavelength range of 1465-1575nm optical intensity changes from 66.94kW/cm2 at ė=1575nm to 70.18kW/cm2 at ė=1470nm. But the nonlinear refractive index change in the erbium doped amplifier amplification range is found to be 1.04 times
Estimation of Erbium Doped Optical Fiber Nonlinear Coefficient
No full textFor wavelength division multiplexing (WDM) technology the preference is given to the erbium-doped optical fiber amplifiers (EDFAs). EDFA working principle is based on optical signal amplification using stimulated emission in the fibers with a small controlled amount of erbium added to SiO2 in the form of Er3+ ion. Erbium doped fibers (EDF) typically have smaller core size than standard ITU-T G.652 fiber to achieve single mode propagation at both: pump wavelength at 980nm and amplification range from 1525 to 1565 nm. Because of smaller core size optical radiation intensity in such a fiber is higher and can cause nonlinear optical effects (NOE) appearance
Comparison of Different FWM Realization Methods in Optical Fibre
No full textThis paper is based on simulations that was performed by OptSim 5.0 Simulation Platform. We have considered two different FWM realisation schemes and have compared them by achievable nonlinear interaction for different optical power and wavelength separation
Optical Fiber Effective Area Measurements
No full textOne of limiting factors for data transfer capacity in fiber optics transmission systems is optical fiber nonlinear response to high intensity optical radiation. The main reason for optical signal high intensity is optical fiber core size. For single mode fiber it is typically around 10µm in diameter. In addition optical field in a telecommunications single mode fiber is not evenly distributed or even fully contained within the core. It is larger at the fiber central axis than near the core-cladding interface and extends even into the cladding depending on the actual refractive index profile. The real optical fiber refractive index profile is dependent on the fiber type and the manufacturing process and therefore not always can be accurately determined. The effective area parameter Aeff has been defined for the purposes of calculating nonlinear effects. It is a single value, based on the modal field distribution, and can be used to calculate a value of optical intensity
Interaction between Electromagnetic Field and Optical Signal Transmission in Fiber Optics
No full textThe area of electromagnetic (EM) field influence to FOTS has not been widely studied. Main reason is that for data transmission speeds used in optical fibers nowdays there are no indication of EM influence. But we propose that EM interference with optical radiation could become a limiting factor for much higher data transmission speeds. Therefore the aim of this research is to evaluate external EM field influence to fiber optics WDM transmission system with standard data transmission speed per channel 10.52, 12.5 and 40.0 Gbps and two different modulation formats: amplitude and polarization state modulation
Estimation of Erbium Doped Optical Fibers Effective Area
No full textErbium doped fiber amplifiers (EDFAs) are one of the most extensively used optical amplifiers in the fiber optics transmission systems. EDFA working principle is based on erbium doped fiber (EDF) application to amplify optical signal at wavelength region used in telecommunications.
Optical amplification is related with high optical signal power and therefore high optical radiation intensity in the fiber. Due to optical fiber nonlinear characteristics at high optical intensity nonlinear effects can occur in EDF simultaneously with amplification. To assess nonlinear effects in the fiber very important parameter is an optical intensity that depends on input optical power and fiber effective area Aeff. The aim of this research is to estimate EDF Aeff changes at different input optical radiation wavelength and power levels to study optical intensity changes.
Measurement setup (Fig.1.) consists of tunable laser source, micro-positioner, optical power meter and fiber under test. Measurements were performed at different optical radiation wavelengths that are characteristic to EDFA operation: 980nm and 1480nm as erbium excitation wavelength and couple wavelengths from EDFA amplification range from 1520nm to 1630nm. Each measurement was performed at three different optical power levels 8, 10 and 12 dBm. The measured values of the fiber effective area are in the range from 49.50μm2 at λ=980nm and Pin=8dBm to 76.34μm2 at λ=1630nm and Pin=12dBm. It was found out that for 980nm measured effective area is considerably smaller than for other wavelength.
IEEE Catalog Number: CFP1130R-USB ISBN: 978-1-4577-1876-
Estimation of Variables Affecting Parametric Amplification in Fiber Optics
No full textFour-wave mixing (FWM) is referred
to as a parametric process and one of useful
applications is using it for optical signal
amplification. One of advantages of fiber
optics parametric amplifiers (FOPAs) over
broadly used conventional EDFAs (erbium
doped fiber amplifiers) is the ability to tune
the amplification wavelength region of
FOPA which is not possible with EDFA,
whose gain bandwidth is limited between
1530 and 1565 nm [2]. This feature of
FOPAs makes it possible to utilize them for
light amplification in S (1460 to 1530 nm)
and L (1565 to 1625nm) optical bands
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