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A broadband amplification that utilizes a serial hybrid fiber amplifier is experimentally demonstrated in this paper. Two fully double-pass configurations, namely, setups A and B, are implemented. The difference between these two configurations is that the position of the two amplifiers (erbium and Raman) is swapped. These two configurations are tested under the same input parameter conditions. Two laser pump power wavelengths with a total pump power of 375 mW (1495 nm with 350 mW for Raman and 1480 nm with 25 mW for the erbium amplifier) were used. Under the optimum condition and under a small signal power of −30 dBm, a wide flatness gain bandwidth of 80 nm (1530–1610 nm) with an average gain level of 28.5 and 24 dB is achieved for setups A and B, respectively. A wide bandwidth is achieved by avoiding the amplification overlap between these two amplifiers through choosing the proper pump wavelength. In addition, A gain dynamic range values of 3 dB and more than 15 dB were recorded for setup A and B respectively. [ABSTRACT FROM AUTHOR]

Extending the sensing range for monitoring the railways, pipelines, borders, long structures, etc., has great importance in distributed fiber optic sensors development. Phase-sensitive optical time-domain reflectometry (φ-OTDR) sensors are the best candidate for this purpose. Optical fiber amplifiers in φ-OTDR sensors have increased the sensing range. A φ-OTDR sensor using combination of Erbium and Raman amplifiers has been demonstrated with a sensing range of 128 km. In this paper, we presented a disturbance monitoring up to 150 km utilizing Erbium and bi-directional Raman amplifications. In the proposed sensor, disturbances at 30, 70 and 120 km distances are applied and Rayleigh backscattered signals are investigated. [ABSTRACT FROM AUTHOR]

This paper presents a performance analysis and comparison of optimized multipump Raman and hybrid erbium-doped fiber amplifier (EDFA) + Raman amplifiers, operating simultaneously at conventional (C) and long (L) bands, using multiobjective optimization based on evolutionary elitist nondominated sorting genetic algorithm. The amplifiers performance was measured in terms of on-off gain, ripple, optical signal-to-noise ratio (OSNR) and noise figure (NF), after propagating over 90 and 180 km of single-mode fiber (SMF). Numerical simulation results of the first analysis show that only three pumps are necessary to generate optimal gains in both amplifiers. Comparing the results of the second performance analysis, we conclude that, after 90 km SMF, the two amplifiers has the same on-off gain, if the total pump power (1807.1 mW) of the Raman amplifier is approximately double (100 + 994.7 mW) of the hybrid amplifier, when the EDFA is operating at 1480 nm with 5 m of doped fiber. Furthermore, the Raman amplifier needs a single laser with at most 741.1 mW, against 343.9 mW of the distributed Raman amplifier (DRA) pump in the hybrid system. Finally, the results of the last analysis, which considers only the EDFA + Raman amplifier, shows that with on-off gain of 26.14 dB, ripple close to 1.54 dB over a bandwidth of 66 nm and using three pumps lasers in the DRA the achieved OSNR was 39.6 dB with an NF lower than 3.3 dB, after 90 km of SMF. [ABSTRACT FROM AUTHOR]

An Er/Yb co-doped fiber/Raman hybrid amplifier (HA) is proposed and studied theoretically and analytically to improve the gain and noise figure of optical amplifiers. The calculations are performed under a uniform dopant and steady-state conditions. The initial energy transfer efficiency for Er/Yb co-doped fiber amplifier (EYDFA) is introduced, while the amplified spontaneous emission (ASE) is neglected. The glass fiber used for both Er/Yb and Raman amplifiers is phosphate. Different pump powers are used for both EYDFA and RA with 1 μW input signal power, 1 m length of Er/Yb amplifier and 25 km length of Raman amplifier (RA). The proposed model is validated for Er/Yb co-doped amplifier and Raman amplifier separately by comparing the calculating results with the experimental data. A high gain and low noise figure at 200 mW Raman pump power and 500 mW Er/Yb pump power are obtained for the proposed HA as compared with the experimental results of EYDFA, Raman amplifier and the EDFA/Raman hybrid amplifier. [ABSTRACT FROM AUTHOR]

This study demonstrates simulation and experimental validation of a wideband serial hybrid Raman/erbium-doped fiber amplifier. Two configurations are adopted; in type A, a Raman amplifier is the first stage, and in type B, an erbium-doped fiber amplifier is the first stage. At low input signal power, the average gain level is 20 dB with a flat gain bandwidth of 40 nm for both configurations. The noise figure in type B is dominated by the erbium-doped fiber amplifier and produces lower values and flatter spectra than in type A. The gain of the proposed hybrid amplifiers is affected more by the second amplification stage. [ABSTRACT FROM PUBLISHER]

Nowadays, optical amplifiers designs are induced by new requirements generated by optical networks. The introduction of WDM reconfigurable networks with increasing rate from 10-40 Gb/s to 100 Gb/s and beyond, demand new optical amplifiers development with improved gain spectral flatness and noise figure for all operational range of input powers and set-point gains. In this paper, it was developed a hybrid distributed Raman/EDFA amplifier with a novel hybrid gain control (HGC) scheme based on joint actuation. The HGC was firstly developed by numerical simulation and after experimentally, in a WDM system with 100 km SSMF fiber span and full C-band load. The Results shows an improved equivalent noise figure with flattened gain spectrum for all amplifier operation range in dynamic optical networks. [ABSTRACT FROM AUTHOR]

This study demonstrates a broadband gain-clamped and gainflattened dispersion-compensated Raman/erbium-doped fiber hybrid amplifier that recycles residual Raman pump power using a single fiber Bragg grating for wavelength-division multiplexing systems. The optimum gain-clamped wavelength was 1564 nm. A gain variation of less than 0.21 dB can be achieved from 1525 to 1625 nm, and the dynamic input power exceeds 18 dB, ranging from -20 to -2 dBm. Further, a gain ripple of ±1.75 dB can be achieved from 1530 to 1595 nm. [ABSTRACT FROM AUTHOR]

An experimental comparison of the stability performance of two multiwavelength lasers, based on either an erbium- doped fiber or Raman amplification, is reported. Both systems employ fiber Bragg gratings to select the operating wavelengths within the resonant ring cavity. The aim of this study is to compare the output power stability of the lasers and also their optical SNR ratios. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a flexibly tunable multiwavelength fiber ring laser with a continuous wavelength spacing tunability, incorporating a superimposed chirped fiber Bragg grating (CFBG) at room temperature. We exploit versatile gain media such as erbium-doped fiber (EDF) and Raman amplifiers in generating the multiwavelength fiber ring laser. The wavelength spacing of a superimposed CFBG can be continuously controlled by modifying the chirp ratio of the grating with the specially designed apparatus. After configuring a fiber ring cavity with the proposed multichannel filter, we realize stable multiwavelength fiber ring lasers at room temperature, which are based on an EDF amplifier incorporating a highly nonlinear dispersion-shifted fiber or a Raman amplifier using a dispersion-compensated fiber. Power fluctuation is less than ~0.6 dB. No lasing wavelength change is severally observed for the whole tuning range. For the multiwavelength EDF laser, stable 11-wavelength simultaneous operation spaced at 0.51 nm, with a signal-to-noise ratio (SNR) of more than ~45 dB at room temperature, is achieved. A high-quality multiwavelength Raman laser output with stable 30 lasing wavelengths spaced at 0.51 nm with a high SNR of more than ~45 dB is also realized. By applying the proposed tuning technique to both the multiwavelength EDF and Raman lasers, a wide and continuous tunability of lasing wavelength spacing is successfully achieved, which is measured to be ~ plusmn0.033 nm/mm. By controlling the pump power in the multiwavelength Raman fiber ring laser, we can control the number of lasing channels at a wavelength spacing of 0.51 nm. [ABSTRACT FROM PUBLISHER]

We report a novel hybrid optical amplifier covering S+C+L bands with 105-nm total bandwidth using a silica fiber. The principle of amplification is based on the stimulated radiative transition of Er-ions for C-band and on the stimulated Raman scattering for S- and L-band, respectively. In this letter, we analyze the amplification characteristics for two types of active fiber mediums through numerical simulation. One is a silica fiber configured with Er-doped cladding and Ge-doped core and the other is a medium consisting of Er-doped fiber and dispersion-compensating fiber. By optimizing parameters such as fiber length and pump power, we newly achieve wide-band amplification with 105-nm bandwidth showing a flat gain characteristic over the entire S+C+L bands. [ABSTRACT FROM PUBLISHER]

Enhanced performance of a distributed temperature sensor based on spatially resolving the temperature-dependent intensity of the spontaneous Brillouin scattered signal was accomplished by combining distributed Raman amplification and a remotely pumped erbium-doped fiber amplifier. A temperature resolution of 5.7°C combined with a spatial resolution of 20 m was achieved at a range of 88 km. [ABSTRACT FROM PUBLISHER]

A novel hybrid optical amplifier covering entire S- and C-bands has been proposed. A silica fiber configured with an erbium (Er)-doped cladding and a germanium-doped core was used. Amplification was achieved by stimulated Raman scattering along with the Er ions' radiative transition in a fiber. A numerical simulation has been performed to analyze the amplification characteristics. Fiber parameters such as optical loss, Er concentration, fiber length, and pump power were taken into consideration to calculate the optimum pump power and fiber length for a flat gain characteristic over the entire S- and C-bands. [ABSTRACT FROM PUBLISHER]

We experimentally demonstrate a novel concept of the dispersion-compensating Raman/erbium-doped fiber amplifier hybrid amplifier recycling residual Raman pump for increase of overall power conversion efficiency. The proposed dispersion-compensating hybrid amplifier system has only one pump source for Raman amplification in the dispersion-compensating fiber (DCF) and the residual pump power after the DCF is recycled for secondary signal amplification in an erbium-doped fiber cascaded to the DCF. Using the proposed scheme, we achieve the significant enhancement of both signal gain and effective gain-bandwidth by 15 dB (small signal gain) and 20 nm, respectively, compared to the performance of the Raman-only amplifier. [ABSTRACT FROM PUBLISHER]