Hybrid optical amplifier uses PPLN to eliminate Kerr nonlinearity

Researchers at the University of Southampton (England) and the University of Maryland (College Park, MD) have constructed a hybrid Ononlinearity-freeO optical amplifier using

Hybrid optical amplifier uses PPLN to eliminate Kerr nonlinearity

Researchers at the University of Southampton (England) and the University of Maryland (College Park, MD) have constructed a hybrid Ononlinearity-freeO optical amplifier using

periodically poled lithium niobate (PPLN) and an erbium-doped fiber amplifier (EDFA). The device compensates for Kerr-induced nonlinearity by taking advantage of cascaded nonlinearity in the PPLN. The researchers will describe their experimental device this month in a presentation at the Optical Fiber Communication conference (San Diego, CA).

The first stage of the two-step experiment consisted of amplifying 1.2-ps, bandwidth-limited pulses from a passively modelocked fiber laser in a 2-m-long EDFA and resulted in significant spectral broadening of the input signal. In the second stage of the experiment, the pulse train was passed through a 4-mm-long bulk PPLN crystal with a pitch of 18.3 ?m prior to amplification. The tuning curve for the crystal indicated a negative effective nonlinear refractive index at temperatures in excess of the phase-matching point at 165!C, and the crystal was maintained at about 10!C above phase-matching during the experiment. When the signal was passed through the PPLN prior to amplification, input and output spectra appeared almost identical. Contact Anatoly Grudinin at abg@orc.soton.ac.uk.

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