Cascadability and functionality of all-optical low-birefringent nonlinear optical loop mirror: experimental demonstration

We verify both experimentally and theoretically the cascadability and the Boolean complete functionality of the low-birefringent nonlinear optical loop mirror (low-bi NOLM) operating with all inputs at the same wavelength. We achieve a low switching energy by using a low-birefringent (Δn∼3.5×10-6), polarization-maintaining fiber to achieve a longer interaction length between two orthogonally polarized pulses. We experimentally demonstrate switching in the cascaded operation of two low-bi NOLM's using picosecond pulses from an erbium-doped fiber laser. This has the potential to have a bit rate of 100 Gb/s. After the two cascaded low-bi NOLM's, the performance is a peak switching contrast of 36:1 and a timing window of 1.7 pulse widths with a switching energy of 9 pJ. In addition, we demonstrate the and and the xor/not operations with the low-bi NOLM showing Boolean completeness. The and operation has a switching contrast of 84.5:1, and the xor/not has a switching contrast of 11.5:1. Finally, we study the gate numerically and find good agreement between experiments and simulations.