SLOW-LIGHT PROPAGATION IN EDFs

Slow-light propagation in highly-doped Erbium fibers

We have developed a new experimental research line focused on studying slow light propagation (SLP) in solid materials at room temperature for applications in communications. Slow (fast) light is the propagation of an optical pulse at a very low (high) group velocity. We are developing experiments to generate slow and fast light in Erbium-doped fibers at 1,5 microns based on coherence population oscillations (CPO). A weak field propagates in a transparency hole created in the absorption spectrum by a strong field with a slight different frequency. The population is forced to oscillate at the beat frequency between both fields. We look for different parameters to control the propagation regime.

Dynamic control of group velocity in erbium doped fibers with coherent population oscillations (CPO) by using active Bragg gratings
Slow and fast light propagation in ultra highly-doped Erbium fibers: control of pulse distorsion

This is a photo of our experimental setup inthe QUANTUM COHERENCE LABORATORY

These are our first experimental results in Erbium-doped fibers at 1,5 microns based on coherence population oscillations (CPO), i.e, a weak signal propagates in an absorption hole created by a stronger signal with a slightly different frequency. We used a diode laser at 1536 nm with 16 mW. In order to simulate both signals we periodically modulate the laser output (10%) with a frequency between 1 Hz and 10 kHz.

We show in this figure a very high delay, around 1 ms, obtained between the signal propagated through the Erbium-doped fiber and a reference one. The laser output was modulated at 100 Hz. This large time delay remains while the modulation frequency (in terms of CPO the detuning between the weak and strong fields ) has a value lower than the width of the absorption hole (given by the lifetime 10 ms of the metastable level ⁴I_13/2 ).

The fractional advancement shows above presents a large value close to 10%. In the right figure the ratio bewteen the modulation part of the signal (playing the role of the weak field) and the dc part of the signal (playing the role of the strong field) is shown versus the modulation frequency. In this figure we observe the absortion hole due to the CPO phenomenon.

Publications

Research lines of the Laser Physics, Quantum Optics and Non-linear Optics UCM group, Optica Pura y Aplicada 44 (2011) 279-288
Fast light enhancement by bidirectional pumping in erbium-doped fibers, J. Nonlinear Opt. Phys. Mat. 19 (2010) 153-165
Phase-controlled slow and fast light in current-modulated semiconductor optical amplifiers, J. Phys. B: At. Mol. Opt. Phys. 42 (2009) 095403 (1-8)
Propagation-induced transition from slow to fast light in highly doped erbium fibers, Phys. Rev. A 78 (2008) 053812 (1-8)
Effect of ion pairs in fast-light bandwidth in high-concentration erbium-doped fibers, J. Opt. Soc. Am. B 25 (2008) C55-C60
Modulation-frequency-controlled change from sub- to superluminal regime in highly doped erbium fibers, Optics Letters 33 (2008) 827-829
Effect of ion concentration on slow light propagation in highly doped erbium fibers, Opt. Commun. 279 (2007) 53-63

Proceedings: International Meetings

Control of the group velocity of light in Erbium doped fibers via the modulation frequency
2008 Optics and Photonics Congress. Slow and Fast Light Topical meeting, July 13-16, Boston, Massachusetts, USA [Abstract PDF (159 kB)][Talk PDF (1788 kB)]
Modulation-frequency-controlled change from sub- to super-luminal regime in highly-doped erbium fibers
2007 2nd Meeting of the Spanish Thematic Network on Quantum and Non-Linear Optics, September 5-7, Salamanca, Spain [Poster JPG (262 kB)]
Slow light propagation experiments in highly-doped erbium fibers
2006 Slow and Fast Light Topical meeting, July 23-26, Washington DC [Abstract PDF (159 kB)] [Talk PDF (344 kB)]

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