Abstract

GARCIA CASILLAS, D.; STEPANOV, S.  and  PLATA SANCHEZ, M.. Linearizing response of adaptive interferometer based on dynamic grating in erbium-doped fiber with saturable absorption. Rev. mex. fis. [online]. 2007, vol.53, n.2, pp.144-148. ISSN 0035-001X.

Because of the unshifted type of recorded amplitude gratings, adaptive interferometers based on dynamic population gratings in Er-doped fibers with saturable absorption demonstrate an essentially quadratic response and, as a result, are not sensitive enough to detect a small object displacement (<< λ/4), and cannot distinguish the displacement direction. We propose, and experimentally demonstrate, two techniques for their linearization which are based on externally introduced phase off-set between the recording interference pattern and the recorded grating. In the transient technique, the application of a fast /2 phase jump in the detected wave makes the system response linear during the transient time of the grating formation τ ₉ (typically of a millisecond-submillisecond scale in Er-doped fibers). In the continuous technique, the introduction of a permanent frequency off-set ΔΩ₀ into the detected wave linearizes the system response permanently.

Keywords : Adaptive interferometry; population gratings; erbium-doped fiber.

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