Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers

Kafing Keïta (1, 2) , Philippe Delaye (2) , Robert Frey (2) , Gérald Roosen (2)

1 Thales Research and Technology [Palaiseau]
2 Laboratoire Charles Fabry de l'Institut d'Optique / Manolia

A theoretical analysis of the Raman amplification in optical fibers and the pump-to-signal relative intensity noise (RIN) transfer has been performed in the spectral domain. An efficient Raman amplification of a monochromatic signal beam by a large-bandwidth pump beam has been demonstrated for a pump bandwidth much smaller than the Raman linewidth. Under the same approximation the pump-to-signal RIN transfer has been calculated in both cases of copropagating and counterpropagating beams in the two limiting cases of modulated monochromatic and smooth-profile large-bandwidth pump beams. At low frequencies the excess of noise evidenced in the case of a modulated monochromatic pump beam did not exist in the case of large-bandwidth pseudoincoherent sources. As this noise reduction can be as large as 13 dB for a 40 dB net gain of the amplifier, such incoherent pumping sources must be considered for the purpose of low-noise Raman amplifiers

Domains: Optics [physics.optics]

Kafing Keïta, Philippe Delaye, Robert Frey, Gérald Roosen. Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers. Journal of the Optical Society of America B, 2006, 23 (12), pp.2479-2485. ⟨hal-00671112⟩