Generation of pulsed squeezed light at telecommunication wavelength using a high efficiency PPLN optical waveguide

Quadrature-squeezed light generated via parametric amplification is an essential resource for continuous-variable quantum communication (CVQC) technology, such as quantum teleportation and dense coding [1], and parametric amplification itself is also important for optical communication technology, e.g. wavelength shifting and optical sampling. Therefore, the development of efficient parametric process is one of the key issues for future information technology. In telecommunication band, observation of 6.4 dB squeezed light using cw light and periodically poled KTiOPO₄ bulk type crystal was recently reported by M. Mehmet et al.[2], and 4.1 dB of pulsed squeezing in periodically poled MgOLiNbO₃ waveguide (PPLN-WG) was reported by Y. Eto et al. [3]. In the latter experiment, squeezing level was mainly limited by optical losses including quantum efficiency of photodiodes.