Erbium-doped Optical Amplifiers Research Articles

Raman and erbium-doped fiber amplifiers hybrid bidirectional optical amplifier with low noise figure for fiber-optic radio frequency synchronization

Raman and erbium-doped fiber amplifiers hybrid bidirectional optical amplifier with low noise figure for fiber-optic radio frequency synchronization

Modeling and simulation of erbium-ytterbium co-doped optical waveguide amplifiers with dual-wavelength pumping at 980 nm and 1480 nm

With the rapid development of silicon photonic chips and integrated photonic circuits, erbium-doped optical waveguide amplifiers have received more and more attention in order to compensate for the transmission and coupling losses caused by the integration of optical devices on a chip. Pumping wavelength and pumping efficiency directly affect the gain and noise figure of the amplifier. In this paper, we propose an innovative dual-wavelength pumping method based on an erbium-ytterbium co-doped optical waveguide amplifier with simultaneous pumping at 980 nm and 1480 nm. A relaxation method based on the fourth-order Range-Kutta method is used to solve the rate and propagation equations and simulate the gain characteristics of the dual-wavelength pumping method for different ytterbium-erbium ion concentration ratios, erbium ion concentrations and ratio K between the 980 nm and total pump power. From the simulation results, it can be seen that the gain of the dual-wavelength pumping method is higher than that of the single-wavelength pumping methods when the erbium ion concentration exceeds 3 × 1026 m−3. At higher erbium ion concentrations, the dual-wavelength pumping method can provide higher gain for optical waveguide amplifiers, and may be able to become a new choice of pumping method for optical waveguide amplifiers.

MATHEMATICAL MODELING OF FIBER-OPTIC TRANSMISSION SYSTEM WITH INTENSITY MODULATION

Fibre optic transmission systems are widespread in the transport network. Optical Transport Hierarchy (OTH) transmission systems are the basis of the transport network. The principle of wavelength multiplexing of channels is used to increase the technical and economic performance. Technically a simpler type of intensity modulation is used to transmit OTU1 and OTU2 OTH frames. Erbium-doped fibre-based optical amplifiers also generate amplified spontaneous emission noise, which degrades the performance of the transmission system. The qualitative characteristics of the optical channel of OTH transmission system with intensity modulation are investigated in this paper. In the simulation process, it is possible to neglect the nonlinear signal distortion in the optical fiber at the nominal signal power of the transponder transmitter. Therefore, in the studied transmission system model, an optical oscillation consisting of two components (signal and noise) arrives at the receiver input. In this case, an electrical signal consisting of three summands (signal-signal, signal-noise and noise-noise) will be generated at the output of the photodiode. A simplified formula for calculating the Q-factor of the optical signal, which affects the error probability in the optical channel, is proposed in most of the specialized literature. Numerical Q-factor values were calculated for OTU1 and OTU2 frames. They were compared with the reference results which were obtained by simulation in Optiwave Optisystem software. The analysis of the obtained data has proved that the simplified formula for the calculation of the Q-factor has a relative error of the order of 39-59%. A more accurate result can be obtained by using an expression that takes into account both components of the noise at the photodiode output.

Design of an erbium-doped Al[formula omitted] optical waveguide amplifier with on-chip integrated laser pumping source

Erbium-doped optical waveguide amplifier (EDWA) is an important building block for conventional and integrated optical communication and light signal processing systems. In recent years remarkable advancement has been achieved for EDWA to meet the demand for silicon photonic chips and integrated photonic circuits. However, in the currently demonstrated EDWAs all the laser pumping sources are external or off-chip, which not only limits the application field of EDWA, complicates the amplification scheme, but also does not fulfill the expectation of monolithic integration. In this work we propose a design of EDWA using high-gain Er-doped Al2O3 waveguide, low-loss silicon-on-insulator (SOI) waveguide, and on-chip integrated semiconductor laser pumping source. The 1550 nm signal light and 1480 nm pump light are transmitted and combined in SOI waveguide and coupled into the EDWA waveguide embedded in the adjacent layer. The 1480 nm pump light is coupled into the SOI waveguide from a bonded hybrid III–V semiconductor laser. The pump and signal waveguide building scheme, the coupling method and structure, and the integration process of laser pumping source are shown and simulated. The system performance was evaluated by using the device’s structure parameters and Er3+ rate equation model. More than 1 dB/cm net gain and up to 35 dB maximum net gain can be achieved at about 100 mW pump power. It indicates that such an on-chip integration design is feasible and fully on-chip integrated optical waveguide amplifier could be achieved.

Differential Gain Comparison of Optical Planar Amplifier on Silica Glasses Doped with Bi-Ge and Er, Yb Ions

The paper presents the measurement and calculation of the optical amplifier gain and the optimal length of the active optical amplifier waveguide doped with Bi-Ge radiation complexes compared to an optical amplifier with active doping with ions Er3+, Yb3+. At present are using optical amplifiers for the high-capacity optical communication systems in the narrow spectral region of 1530–1560 nm, determined by the gain bandwidth of erbium-doped fiber amplifiers (EDFA) or erbium-doped optical planar amplifiers (EDPA) realized as active planar waveguides in the optical integrated circuits technique. However, it is possible increase wavelength region up to 1610 nm, where optical losses of telecommunication fibers are less than 0.3 dB per km, if appropriate amplifiers are available. In this regard, the development of novel optical amplifiers operating in this spectral region have of great importance. The paper summarizes the results measurement of the attenuation and emission spectra for net gain spectra calculation of the new ion exchange Ag+ – Na+ optical Er3+ and Yb3+ doped active planar waveguides realized on silica glass substrates and parameters of novel optical amplifiers for extension of the bandwidth from 1530 to 1610 nm doped by bismuth – erbium ions.

Design of a Multi Mode Interferometer using LC:PDMS technology

Multimode interference (MMI) couplers have received more attention in recent years due to their significant role played in telecommunications. Their unique features are compactness, relaxed design constrains, large optical bandwidth. In this paper a theoretical analysis and design of a MMI acting as multi/demultiplexer based on liquid crystals (LC) embedded in polydimethylsiloxane (PDMS) channels named LC:PDMS waveguides is presented. Such a device is capable of operating at two different wavelengths, typically used in erbium-doped fiber optical amplifiers, 980 and 1550 nm with an extinction ratio higher than 11 dB. The LC:PDMS MMI operation is tuned by applying an electric field by using coplanar electrodes whose fabrication process is described.

Performance Analysis of FBG WDM System using Different Optical Amplifiers

Abstract This paper aims to analyze the performance of FBG 60 channel wavelength-division multiplexing system using different optical amplifiers namely RAMAN, erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) separately at 10 Gbps data rate up to a fiber length of 280 km. Based upon the results, the performance of the three amplifiers has been compared on the basis of multiple performance parameters. It is seen that EDFA simulates good results in terms of bit error rate (BER) up to a fiber distance of approximately 80 km and Q factor up to a distance of approximately 90 km among all the three amplifiers. However, power received is least in EDFA. RAMAN amplifier provides a better Q factor after the fiber distance of approximately 90 km and a better BER after the fiber distance of approximately 80 km compared to the other three amplifiers. SOA shows better results in terms of power received up to a fiber distance of approximately 100 km. RAMAN amplifier provides better output power after a distance of 100 km. Eye diagrams and power spectrums of the network with different optical amplifiers has also been analyzed.

Synthesis, Structure and Photoluminescence Performance of a New Er3+-Cluster-Based 2D Coordination Polymer

A new Er3+-cluster-based 2D coordination polymer with the formula {[Er(SSA)·(H2O)2]·(H2O)}n (SSA = 5-sulfosalicylic acid), complex 1, has been successfully synthesized via hydrothermal method and structurally characterized by elemental analysis, FT-IR, UV, single crystal and powder X-ray diffraction. Complex 1 reveals the Erbium atom is coordinated to eight oxygen atoms by four symmetry-related SSA ligands and two coordinated water molecules to form a distorted square-antiprismatic geometry. The photoluminescence spectrum of the complex 1 display intense pink emission with CIE chromaticity coordinates (0.540, 0.250). The complex 1 emit NIR luminescence at 1535 nm, which corresponds to the 4I13/2–4I15/2 transition of Er3+ ion. Moreover, its full width at half maximum values is 113 nm. This complex can potentially be applied to polymeric erbium-doped optical amplifiers, planar waveguides or infrared OLEDs.

Efficient ridge waveguide amplifiers and lasers in Er-doped lithium niobate by optical grade dicing and three-side Er and Ti in-diffusion

Highly efficient erbium-doped titanium in-diffused ridge waveguide optical amplifiers and lasers in x-cut congruent LiNbO3 pumped at 1486 nm have been developed. A total internal gain of 14 dB has been achieved in 4.6 cm-long waveguides for a coupled pump power of 200 mW. We demonstrated a laser operating at 1561 nm with a slope efficiency of 33% exceeding the best literature values for Er:Ti:LiNbO3 waveguide lasers. To improve the amplifier/laser performance, our novel fabrication technique of three-side Er and Ti in-diffusion into pre-defined ridges was used.

Er:Ti:LiNbO3 ridge waveguide optical amplifiers by optical grade dicing and three-side Er and Ti in-diffusion

Erbium-doped titanium in-diffused ridge waveguide optical amplifiers in x-cut congruent LiNbO3 substrates pumped by a 1486 nm laser diode are reported for the first time. High internal gain of 2.7 dB/cm has been demonstrated in 2.5 cm long waveguides for the coupled pump power 200 mW exceeding the best literature values reported for Er:Ti:LiNbO3 channel waveguides. For gain improvement, we have developed a novel technique which is comprised of ridge definition using diamond blade dicing followed by three-side erbium (Er) and titanium (Ti) layer deposition and high-temperature diffusion. Thereby both higher Er concentrations with more symmetric diffusion profiles and lower scattering losses due to the high-temperature smoothened waveguide side walls have been obtained.

Link Power Level Improvements in an Amplified 8-Channel CWDM System with Hybrid EDFA-SOA Pre-Amplifier

The link power improvement in a coarse wavelength division multiplexing (CWDM) system which is transmitted using a hybrid erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) scheme as a pre-amplifier, is discussed. The network is designed for amplifying 8 CWDM channels ranging from 1471 nm to 1611 nm. The hybrid amplifiers’ gain measurement is obtained from experimental work with gain peak at 22 dB which is observed at 1531 nm. The amplifiers also caused power increment of 5.06 dB in the transmission link before the signal is split individually at the receiving end. Based on the higher gain peaks and power spectrum at 1531 nm and 1551 nm wavelengths, the proposed amplified link would be useful for the transmission of video applications.

150 x 120 Gb/s unrepeatered transmission over 409.6 km of large effective area fiber with commercial Raman DWDM system.

15 Tb/s unrepeatered transmission is achieved over 409.6 km (68.2 dB) of large effective area fiber using forward and backward distributed Raman amplification and a remotely-pumped erbium-doped optical amplifier. This result provides a record capacity-reach product of 6.14 Pb/s-km over a single fiber type. We also demonstrate channel growth from 10 to 150 waves within 61 nm amplification bandwidth.

X-ray analysis, molecular modeling and NIR-luminescence of erbium(III) 2,4-octanedionate complexes with N,N-donors

X-ray diffraction and semiempirical methods have been used to investigate the structures of novel erbium(III) [Er(od)3(N,N-donor)] complexes, where od=2,4-octanedionate and N,N-donor=2,2′-bipyridine (bipy), bathophenanthroline (bath) or 5-nitro-1,10-phenanthroline (5NO2phen). Structural characteristics for these ternary complexes were also obtained by FTIR spectra. Subsequently, the visible and near-infrared luminescence properties of the compounds have been studied. Upon ligand excitation, the complexes show strong near-infrared luminescence at 1530nm due to antenna effect. These erbium(III) complexes can potentially be applied to polymeric erbium-doped optical amplifiers, planar waveguides or infrared OLEDs.

O-band to C-band wavelength converter by using four-wave mixing effect in 1310 nm SOA

In this paper we provide a detailed account of an ultra-wideband wavelength converter that shifts from 1310 to 1550 nm using a 1310 nm semiconductor optical amplifier as the nonlinear medium. The experimental approach uses an arrayed waveguide grating (AWG) as a method to slice the broadband output ASE of the 1310 nm SOA into multiple outputs at this O-band. A four-wave mixing technique is used to generate the wavelength conversion, whereby two wavelengths at 1310 nm are used and interact with the 1550 nm continuous wave output from a bismuth-based erbium-doped optical amplifier. In this demonstration, the interacting wavelengths are 1316.75, 1317.47 and 1542.21 nm. The downward conversion wavelengths are 1542.93 and 1541.49 nm, with a converted wavelength spacing of 224 nm.

Erbium-doped GaN optical amplifiers operating at 1.54 μm

Strip optical waveguides based on erbium (Er)-doped AlGaN/GaN:Er/AlGaN heterostructures have been fabricated and characterized in the optical communication wavelength window near 1.54 μm. The propagation loss of these waveguide amplifiers have been measured at 1.54 μm and found to be 3.5 cm−1. Moreover, the optical amplification properties of the waveguides were measured using a signal input at 1.54 μm and a broadband GaN light-emitting diode at 365 nm as pump source. A relative signal enhancement of ∼8 cm−1 was observed. The implications of such devices in photonic integrated circuits for optical communications are discussed.

Bit error rate reduction by power shaping in WDM networks with EDFAs

The trend in multi-wavelength optical networks is toward dynamic route and wavelength assignment to support burst-switching or packet switching. Where erbium-doped optical amplifiers (EDFAs) are used for multi-wavelength amplifications, the time interval between traffic blocks can be long enough to induce EDFA optical power transients created by abrupt changes in the average input power to the EDFAs and can adversely affect the performance of the network. To mitigate the effects of EDFA optical power transients on optical networks, a method based on power shaping where heads and tails are joined to the beginning and end of a traffic block is proposed. A head (tail) gradually increases (decreases) the channel power by employing a pseudo-random bit sequence in which the probability of a “1” (“0”) increases from 0 to 0.5. This paper reports experimental results showing that EDFA optical power transients can be significantly reduced with adequate shaping periods. The effects of alternative shaping profiles are examined, and for a linear shaping profile, experiments show that the drop transient deviation is reduced by 0.5 dB while the add transient deviation is reduced by 0.71 dB. We show by lab experiments that the bit error rate induced by wavelength add-drop transients in a chain of EDFAs in an emulated fiber network can be reduced by 25% using power shaping techniques. Power shaping is an economical means of suppressing EDFA optical power transients compared to other physical layer approaches that require the addition of specialized components and can be applied to EDFAs as well as other solid-state and Raman optical amplifiers.

Investigations on burst length in optical burst switched networks

In this paper, we investigate the performance of optical burst switched networks for erbium-doped fiber amplifiers (EDFAs) and semiconductor optical amplifiers (SOAs). We show that EDFAs are more suitable for burst switching as compared to SOAs. We further investigate the burst length for 18, 24.6 and 55 km optical switched network. It is observed that burst length should neither be very small nor very large. If the burst length is small, throughput will be less, and if the burst length is very large, delay will be very large. This is due to higher wait times incurred when packets are formed into larger bursts causing additional overall delay. It is observed that performance decreases up to a small burst length of 1500 μs, which is the minimum burst length required for the creation of the burst. Once this burst is created, there is significant improvement in the quality factor up to 3000 μs. After this burst length, the performance again degrades. Hence the burst length can be optimized for the best quality factor in optical burst switched networks. We further show that by increasing EDFA gain, the quality deteriorates as increasing the EDFA gain results in increased levels of additive phase noise, which can further induce nonlinearities.

Comparative analysis of triple band S-C-L erbium-doped fibre and semiconductor optical amplifier for CWDM applications

The authors present a comparative analysis between a triple-band S-C-L erbium-doped fibre amplifier and a commercial semiconductor optical amplifier in a CWDM application scenario. Both technologies were characterised for gain and noise figures from 1480 to 1610 nm (S, C and L bands) and their systemic performances were evaluated in terms of bit error rate measurements for a wide range of optical power levels.

Decreasing EDFA transients by power shaping

Multi-wavelength optical networks make extensive use of erbium-doped optical amplifiers (EDFAs) to offset the effects of fiber attenuation and signal power splitting. As optical networking moves towards burst and packet switching, the effects of changes of optical power levels on one wavelength, or channel, can have an impact on the behavior of other wavelengths passing through the same amplifier and impair network performance. We have observed in our simulations of EDFA operation that both the amplitude and duration of EDFA transients will decrease when gradual changes are made to the input power of the EDFA. It was also verified in [D.H. Richards, J.L. Jackel, M.A. Ali, A theoretical investigation of dynamic all-optical automatic gain control in multichannel EDFA’s and EDFA cascades, J. Select. Top. Quantum Electron. 3 (4) (1997)] that the switching time of the channel dropping operation can influence the amplitude and duration of EDFA transients. We show that this effect can be exploited to successfully suppress EDFA transients by power shaping. Our approach is to increase/decrease the power of an added/dropped channel gradually, rather than abruptly. Power shaping can be implemented by adapting existing link layer protocols. It is general and can be applied to amplifiers using different technologies, including EDFAs, solid state and Raman amplifiers.

Reproducibility of splicer-based long-period fiber gratings for gain equalization

We fabricated long-period fiber gratings (LPFGs) using electric arc discharges. We observed that the fiber becomes slightly tapered due to longitudinal tension during the arc: this effect depends on the arc current and time length. We experimentally investigated how these characteristics can influence grating’s performances, especially in view of employing the LPFG as gain equalizer for an erbium-doped optical amplifier. As expected, we found that the spectral response of the grating depends on the period Λ, the intensity of the perturbation, the grating length and the type of mode-coupling induced. Since this last parameter cannot be estimated directly from the transmission spectra, we propose a method to determine the mode-coupling occurring in the device and to assess the index modulation induced by the electric arcs. This method combines both experimental and simulated data, and can be used to characterize LPFGs made-up by any method.