Generation of squeezed vacuum pulses using cascaded second-order optical nonlinearityof periodically poled lithium niobate in a Sagnac interferometer

摘要

Squeezed vacuum pulses up to —1.7 dB at telecom-band (1550 nm) is generated with femtosecond laserpulses using cascaded X~((2))optical nonlinearity in a periodically poled lithium niobate crystal placed in aSagnac interferometer. In spite of group velocity mismatch at short laser pulse pumping, sufficient cascadednonlinear wave mixing is obtainable at the wavelength shifted from the phase matching wavelength for secondharmonic generation. The theoretical model prediction agrees well with the experimental results.