Elimination of acoustic sensitivity in nonlinear optical loop mirrors

Acoustic disturbance is known to give rise to bit error rate (BER) floor when using the nonlinear optical loop mirror as a switch. Here, the acoustically induced penalty is investigated and >30 dB improvement in the acceptable acoustic sound pressure (50 Hz-5 kHz) is achieved by rewinding the loop fiber symmetrically. Only 1.5 dB sensitivity penalty was observed at a sound pressure of 110 dBA when using a nonlinear optical loop mirror (NOLM) containing 3.9 km of dispersion shifted fiber.