RP Photonics logo
RP Photonics
Encyclopedia
Technical consulting services on lasers, nonlinear optics, fiber optics etc.
Profit from the knowledge and experience of a top expert!
Powerful simulation and design software.
Make computer models in order to get a comprehensive understanding of your devices!
Success comes from understanding – be it in science or in industrial development.
The famous Encyclopedia of Laser Physics and Technology – available online for free!
The ideal place for finding suppliers for many photonics products.
Advertisers: Make sure to have your products displayed here!
… combined with a great Buyer's Guide!
VLib part of the
Virtual
Library

Gain Equalization

<<<  |  >>>

Definition: a technique for making the gain spectrum of an optical amplifier device flatter over a certain optical frequency range

Category: optical amplifiers

How to cite the article; suggest additional literature

The optical gain e.g. from a fiber amplifier has some dependence on the wavelength, which can be disturbing. For example, in optical fiber communications with wavelength division multiplexing, the wavelength dependence of the gain can unbalance the powers in the transmitted channels. Therefore, it is common to apply methods for gain equalization, also called gain flattening. There are various technological options:

The optimization of a multi-stage amplifier with flattening filters is a complex task, since it is not obvious, e.g., which combination of amplifiers and filters gives the best results in terms of noise figure and power efficiency. A typical solution for a two-stage amplifier based on doped silica fibers would include an optical filter between the two stages.

The gain spectrum of a Raman amplifier can be flattened by using multiple pump beams [7] with well-balanced pump power levels.

Bibliography

[1]K. Inoue et al., “Tunable gain-equalization using a Mach–Zehnder optical filter in multistage amplifiers”, IEEE Photon. Technol. Lett. 3, 718 (1991)
[2]S. F. Su et al., “Gain equalization in multiwavelength lightwave systems using acousto-optic tunable filters”, IEEE Photon. Technol. Lett. 4, 269 (1992)
[3]R. Kashyap et al., “Wavelength flattened saturated erbium amplifier using multiple side-tap Bragg gratings”, Electron. Lett. 29 (11), 1025 (1993)
[4]B. Clesca et al., “1.5 μm fluoride-based fiber amplifiers for wideband multichannel transport networks”, Opt. Fiber Technol. 1, 135 (1995)
[5]A. M. Vengsarkar et al., “Long-period fiber-grating-based gain equalizers”, Opt. Lett. 21 (5), 336 (1996)
[6]N. Park et al., “High-power Er–Yb-doped fiber amplifier with multichannel gain flatness within 0.2 dB over 14 nm”, IEEE Photon. Technol. Lett. 8, 1148 (1996)
[7]Y. Emori et al., “100 nm bandwidth flat-gain Raman amplifiers pumped and gain-equalized by 12-wavelength-channel WDM laser diode unit”, Electron. Lett. 35, 1355 (1999)
[8]M. Harurnoto et al., “Gain-flattening filter using long-period fiber gratings”, J. Lightwave Technol. 20 (6), 1027 (2002)
[9]Ik-Bu Sohn et al., “Gain flattened and improved EDFA using microbending long-period fibre gratings”, Electron. Lett. 38 (22), 1324 (2002)

(Suggest additional literature!)

See also: gain, fiber amplifiers, optical filters, wavelength division multiplexing
and other articles in the category optical amplifiers

If you like this article, share it with your friends and colleagues, e.g. via social media:

arrow