This application claims the benefit of Provisional Application No. Claims What is claimed is: An optical element operable to compensate for dispersion associated with a transmission link, the optical element comprising: The optical element of claim 1, wherein the Raman gain fiber has a cut-off wavelength shorter than the pump wavelength so that the gain fiber is single spatial mode for both the pump wavelength and the signal wavelength.
Le Roch, and P. Jaffre Abstract-The interest of the flattened dynamic gain of an In this letter, to widen the wavelength range with no erbium-doped fluorozirconate fiber amplifier is demonstrated in CSO degradation through the optical amplifier, we pro- a lightwave CATV system including a channel subcamer multiplex.
Using two analog DFB laser diodes, one with a pose the use of an erbium-doped fluoride fiber amplifier relatively high chirp, the other with a very low chirp, a compari- EDFFA which is known to exhibit a flat spectrum gain. To date, this is the first report constant.
This comparison was achieved by using two analog DFB signal lasers with two different wavelengths and nm and having different One key parameter for system applications remains to be chirp characteristics.
We observe that with the commer- studied: To compensate the distor- amplifiers. If the signal wavelength is located in laser diode. The erbium-doped silica and erbium-doped the wavelength window where the gain is flat, the alumi- fluoride fiber characteristics are: However, the gain spectrum obtained with alu- The silica matrix composition is SO,-Ge0,-P,O,-Al,O, minosilicate host glass is not flat over a wide wavelength and the fluoride fiber is characterized by a ZrF,-BaF,- range and the peak around nm remains.
This work was supported by the GAIN project no. The gain spectra measurements were performed by scan- PIN ning the E-C-L from to nm with an optical power kept constant at dBm at the fibre amplifier input.
The 0 dBm input power is sufficient to saturate the Fig. Analog system experiment setup. A polarization independent optical spectrum analyser was used for the gain measurements. The nm analog DFB laser is commercially available, while the All the subcarriers simu- lating video sources are spaced by 8 MHz intervals.
For the nm laser, the improve- I: Dynamic gain spectra measured with a small input power of dBm when a high input signal power of 0 dBm saturates the Saturated spectral dynamic gains measured by combin- amplifier at the nm wavelength.
Thus, for the operation measured the intrinsic laser CSO values which are repre- of the analog transmission system, the link budgets are 14 sented by a thick line in Fig. The input coupling losses were about the frequency ranging.
For the measurement of all CSO 2. The basic difference between degradation is the combination between the chirp and the two kinds of amplifiers lies in the gain tilt at the EDFA nonlinearity -. With the laser chirp values studied signal wavelength as shown in Fig.
The experi- used in this experiment, no degradation of the CSO was mental results of Fig. Around nm signal, the gain tilts were 0. The relatively low dynamic ments.
On the other hand, we experimen- retically demonstrated that CSO distorsions can be due to tally demonstrated with a very low chirp laser of 60 the high numerical aperture of the fibre amplifier .
The correlation between saturated dynamic gain spec-  S. Baran, tra shown in Figs. Silberberg Abstract-We observe little or no accumulation of optical- ous optical-filtering schemes to selectively attenuate power variations among wavelength-multiplexed signals as they high-gain channels , .
However, in such schemes, traverse successive stages of a cooled, inhomogeneously broad- ened, erbium-doped fiber-amplifiercascade. The cascade instead inter-channel power variations still accumulate from stage exhibits separate automatic power-regulation of each channel, to stage unless a separate active servo-loop is used for decoupled from other channels, without the use of servo-loops.
When wavelength- amplifiers are placed in cascade, without optical-feedback loops, their gain is effectively clamped on a channel-by- channel basis by the propagating signals themselves. The multiplexed signals traverse a single fiber amplifier, the system thus behaves as a parallel overlay of independent channels experience various gains, determined by the amplifiers for the various channels.
Such a cascade is spectroscopy of the gain medium and the signal and pump expected to be scalable to large numbers of amplifiers, power traversing it. In a single amplifier, these spectral and to be usable in large multiaccess lightwave networks gain variations are generally modest. The serious prob- , where signals traverse dynamically varying paths and lem, however, is that they accumulate from stage to stage, amplifier saturation levels consequently fluctuate.
In moderate-sized point-to-point systems, sists of a cascade of six erbium-doped aluminosilicate boosting the transmitter power for channels with low gain fiber amplifiers. Each is codirectionally pumped with 10 N [ l ] is quite effective. However, this will not generally dBm of light at nm.
The m-long doped fibers were suffice in multipoint-to-multipoint lightwave networks wound into coils of 6-cm diameter, so they could be e. Each fiber ampli- N ultralong-haul point-to-point links.An Erbium doped ring core fibre compatible with the passive RCF used for transmission has been designed and fabricated.
A RCF optical amplifier that provides a gain of 10dB with a mode dependent gain variation of less than 1dB has been realised, however, further work is required to reduce the intrinsic loss of this fibre to increase the gain. Abstract: A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported.
In the wavelength range from nm, small inter-channel gain variations can be achieved. The power of optical channels in WDM systems is not equalized, because of the wavelength dependence of the gain or loss of erbium-doped fiber amplifiers (EDFAs), transmission fiber, dispersion.
A dual-wavelength erbium fiber laser with single-longitudinal-mode characteristic is proposed and demonstrated. The system uses a 7-m-long highly doped erbium-doped fiber as the primary gain medium while two fiber Bragg gratings (FBGs) act as a wavelength selection mechanism.
Erbium-Doped Fiber Amplifiers - Download as Word Doc .doc /.docx), PDF File .pdf), Text File .txt) or read online. Gain equalization of EDFA using leaky structures: and V.
Rastogi, “Inherently gain flattened S-band erbium doped fiber amplifier based on dual core resonantly leaky fiber,” Optics Communications, vol.
, P. Singh and A. Kumar, “Design of dual-core resonant leaky optical fibre based gain flattening filters.