Periodically Poled Lithium Niobate Waveguide Research Articles

Simultaneous label swapping and wavelength conversion of multiple independent WDM channels in an all-optical MPLS network using PPLN waveguides as wavelength converters

This paper presents the demonstration of all-optical simultaneous label swapping and wavelength conversion of multiple independent wavelength-division multiplexed (WDM) channels using periodically poled lithium niobate (PPLN) waveguides as wavelength converters. Label swapping is one of the required functions in the physical layer for efficient data flow control in the proposed multiprotocol label switching (MPLS) networks. The technique operates directly on the optical signal without optoelectronic (O/E) conversion; therefore, it is bit-rate, label length, and protocol/format independent. Experimental results are presented for the label swapping of distinct 8-b-long labels in a system with 2 WDM data channels at 10 Gb/s. There is a guard time of 400 ps between the payload and the label. The power penalty introduced by the method is less than 3 dB. This method can potentially accommodate 10 WDM channels simultaneously over the PPLN waveguide's ∼40 nm /spl lambda/-shifting bandwidth.

Squeezing in a LiNbO3 integrated optical waveguide circuit

We report on traveling-wave quadrature squeezing generated in an integrated optical circuit fabricated with periodicallypoled lithium niobate waveguides. The device integrates a secondharmonic-generation stage, waveguide couplers, spatial mode filters, and a degenerate-optical-parametric-amplification stage. The integrationpromises to create a low power, compact, and simple source of wideband squeezed light. -1 dB of squeezing is directly measured using 20 ps pulses with peak powers near 6W.

PPLN waveguide for quantum communication

We report on energy-time and time-bin entangled photon-pair sources based on a periodically poled lithium niobate (PPLN) waveguide. Degenerate twin photons at 1314 nm wavelength are created by spontaneous parametric down-conversion and coupled into standard telecom fibers. Our PPLN waveguide features a very high conversion efficiency of about 10^(-6), roughly 4 orders of magnitude more than that obtained employing bulk crystals. Even if using low power laser diodes, this engenders a significant probability for creating two pairs at a time - an important advantage for some quantum communication protocols. We point out a simple means to characterize the pair creation probability in case of a pulsed pump. To investigate the quality of the entangled states, we perform photon-pair interference experiments, leading to visibilities of 97% for the case of energy-time entanglement and of 84% for the case of time-bin entanglement. Although the last figure must still be improved, these tests demonstrate the high potential of PPLN waveguide based sources to become a key element for future quantum communication schemes