Single Periodically Poled Lithium Niobate Waveguide Research Articles

Two-Photon Interference Using Background-Free Quantum Frequency Conversion of Single Photons Emitted by an InAs Quantum Dot

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs/GaAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wave packet interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits nonclassical two-photon interference.

Photonic 640-Gb/s Reconfigurable OTDM Add–Drop Multiplexer Based on Pump Depletion in a Single PPLN Waveguide

All-optical time-domain channel extraction and clearing operations based on nonlinear effects in a periodically poled lithium niobate (PPLN) waveguide is investigated at 640 Gb/s. The suitability of this device for 640-Gb/s signal processing has been confirmed exploiting only pump depletion. Moreover, a 640-Gb/s reconfigurable optical time-division multiplexing (OTDM) add-drop multiplexer is demonstrated, using a single PPLN waveguide based on a counterpropagating configuration. Error-free operation confirms the effectiveness of a single device for simultaneous add-drop functions. Reconfigurable operations have been verified through bit error rate measurements, including the case of simultaneous add-drop of multiple channels in the OTDM frame.

Generation of time-bin entangled photon pairs by cascaded second-order nonlinearity in a single periodically poled LiNbO_3 waveguide

Entangled photon pairs are one of the most important resources for the development of quantum communication technologies. In order to produce pulsed photon pairs in the telecommunication band from 1.5 mum pump light, most of the previous experiments used two successive periodically poled lithium niobate (PPLN) waveguides. We report what we believe to be a new method using cascaded second-order nonlinearity in a single PPLN waveguide to produce high-purity time-bin entangled photon pairs. We confirmed the generation of entanglement through a two-photon interference experiment showing a coincidence fringe with a visibility of up to 97%.

Mode tailoring in a ridge-type periodically poled lithium niobate waveguide

We present a simple and powerful method for mode generation and transformation in a ridge-type periodically poled lithium niobate (PPLN) waveguide by the use of second-order nonlinear effect and local-temperature-control technique. We show that a Hermite-Gaussian (HG) mode wave (among HG(00) to HG(22)) can be selectively generated via the quasi-phase-matching (QPM) nonlinear process in a PPLN waveguide by tuning the wavelength of fundamental wave or the temperature of the waveguide. As well, it is demonstrated that HG mode can be transformed into Laguerre-Gaussian (LG) one via combination of HG modes which are simultaneously generated in a single PPLN waveguide with local-temperature-control technique.

160 Gb/s Time-Domain Channel Extraction/Insertion and All-Optical Logic Operations Exploiting a Single PPLN Waveguide

160 Gb/s all-optical signal processing is demonstrated exploiting pump depletion in addition to sum and difference frequency generation (SFG/DFG) in a single periodically poled lithium-niobate (PPLN) waveguide. 160 Gb/s time-domain extraction and insertion operations of channels are obtained in an optical time division multiplexing (OTDM) system. Moreover, 160 Gb/s digital operations including half-adder, half-subtracter and AND/OR/XOR functions are carried out. The use of pump depletion effect allows to process ultrafast signals due to its high efficiency and ultrafast dynamics. 160 Gb/s bit error rate (BER) measurements confirm the effectiveness of all presented functionalities.