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On the distribution of 1550-nm photon pairs efficiently generated using a periodically poled lithium niobate waveguide  [PDF]
Shigehiko Mori,Jonas Soderholm,Naoto Namekata,Shuichiro Inoue
Physics , 2005, DOI: 10.1016/j.optcom.2006.02.010
Abstract: We report on the generation of photon pairs in the 1550-nm band suitable for long-distance fiber-optic quantum key distribution. The photon pairs were generated in a periodically poled lithium niobate waveguide with a high conversion-efficiency. Using a pulsed semiconductor laser with a pulse rate of 800 kHz and a maximum average pump power of 50 muW, we obtained a coincidence rate of 600 s^-1. Our measurements are in agreement with a Poissonian photon-pair distribution, as is expected from a comparison of the coherence time of the pump and of the detected photons. An average of 0.9 photon pairs per pulse was obtained.
Nonlinear Cascaded Femtosecond Third Harmonic Generation by Multi-grating Periodically Poled MgO-doped Lithium Niobate  [PDF]
Shuanggen Zhang, Wenchao You, Zhangchao Huang
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B012
Abstract:

Nonlinear cascaded femtosecond third harmonic generation was experimentally investigated pumped by 100 fs pulses at optical communication band 1550 nm using a multi-grating 5 mol. % MgO-doped periodically poled lithium niobate crystal. The optimized efficiency of 10.8% was achieved with the simultaneous phase-matching of the second harmonic and sum frequency process. And the third harmonic spectrum reached as broad as 8.7 nm because of the choosing of a small group velocity mismatching between the fundamental and second harmonic pulses. Nonlinear cascaded method will provide a reference for the efficient frequency conversion in the high intensity range.

Analysis of the generation of photon pairs in periodically poled lithium niobate  [PDF]
Jonas Soderholm,Keiichi Hirano,Shigehiko Mori,Shuichiro Inoue,Sunao Kurimura
Physics , 2005, DOI: 10.1142/9789812773210_0011
Abstract: The process of spontaneous parametric down-conversion (SPDC) in nonlinear crystals makes it fairly easy to generate entangled photon states. It has been known for some time that the conversion efficiency can be improved by employing quasi-phase-matching in periodically poled crystals. Using two single-photon detectors, we have analyzed the photon pairs generated by SPDC in a periodically poled lithium niobate crystal pumped by a femtosecond laser. Several parameters could be varied in our setup, allowing us to obtain data in close agreement with both thermal and Poissonian photon-pair distributions.
Generation of polarization entangled photons using type-II doubly periodically poled lithium niobate waveguides  [PDF]
K. Thyagarajan,K. Sinha,J. Lugani,S. Ghosh,A. Martin,D. B. Ostrowsky,O. Alibart,S. Tanzilli
Physics , 2009, DOI: 10.1103/PhysRevA.80.052321
Abstract: In this paper, we address the issue of the generation of non-degenerate cross-polarization-entangled photon pairs using type-II periodically poled lithium niobate. We show that, by an appropriate engineering of the quasi-phase-matching grating, it is possible to simultaneously satisfy the conditions for two spontaneous parametric down-conversion processes, namely ordinary pump photon down-conversion to either extraordinary signal and ordinary idler paired photons, or to ordinary signal and extraordinary idler paired photons. In contrast to single type-II phase-matching, these two processes, when enabled together, can lead to the direct production of cross-polarization-entangled state for non degenerate signal and idler wavelengths. Such a scheme should be of great interest in applications requiring polarization-entangled non degenerate paired photons with, for instance, one of the entangled photons at an appropriate wavelength being used for local operation or for quantum storage in an atomic ensemble, and the other one at the typical wavelength of 1550 nm for propagation through an optical fiber.
Continuous-wave backward frequency doubling in periodically poled lithium niobate  [PDF]
Salvatore Stivala,Alessandro C. Busacca,Luciano Curcio,Roberto L. Oliveri,Stefano Riva-Sanseverino,Gaetano Assanto
Physics , 2012, DOI: 10.1063/1.3364934
Abstract: We report on backward second-harmonic-generation in bulk periodically poled congruent lithium niobate with a 3.2 microns period. A tunable continuous-wave Ti:sapphire laser allowed us exciting two resonant quasi-phase-matching orders in the backward configuration. The resonances were also resolved by temperature tuning and interpolated with standard theory to extract relevant information on the sample.
Generation of continuous-wave broadband Einstein-Podolsky-Rosen beams using periodically-poled lithium niobate waveguides  [PDF]
Ken-ichiroh Yoshino,Takao Aoki,Akira Furusawa
Physics , 2006, DOI: 10.1063/1.2437057
Abstract: Continuous-wave light beams with broadband Einstein-Podolsky-Rosen correlation (Einstein-Podolsky-Rosen beams) are created with two independent squeezed vacua generated by two periodically-poled lithium niobate waveguides and a half beam splitter.
Chirality control by electric field in periodically poled MgO-doped lithium niobate  [PDF]
Lei Shi,Linghao Tian,Xianfeng Chen
Physics , 2012,
Abstract: We study the chirality of periodically poled MgO-doped lithium niobate (MgO:PPLN) by electro-optic (EO) effect. It shows that optical propagation is reciprocal in MgO:PPLN when quasi-phase-matching (QPM) condition is satisfied, which is similar to natural optical active material like quartz. The specific rotation of MgO:PPLN by EO effect is shown to be proportional to the transverse electric field, making large polarization rotation in optical active material with small size possible. We also demonstrate that the chirality of MgO:PPLN can be controlled by external electric field.
Highly efficient photon-pair source using a Periodically Poled Lithium Niobate Waveguide  [PDF]
S. Tanzilli,H. de Riedmatten,W. Tittel,H. Zbinden,P. Baldi,M. de Micheli,D. B. Ostrowsky,N. Gisin
Physics , 2000,
Abstract: We report on a new kind of correlated photon-pair source based on a waveguide integrated on a Periodically Poled Lithium Niobate substrate. Using a pump laser of a few micro-Watts at 657 nm, we generate degenerate photon-pairs at 1314 nm. Detecting about 1500 coincidences per second, we can infer a conversion rate of 10-6 pairs per pump photon, which is four orders of magnitude higher than that obtained with previous bulk sources. These results are very promising for the realization of sources for quantum communication and quantum metrology experiments requiring a high signal-to-noise ratio or working with more than one photon-pair at a time.
3D-PSTD for modelling second harmonic generation in periodically poled lithium niobate ridge-type waveguides  [PDF]
Fabrice Devaux,Mathieu Chauvet
Physics , 2015,
Abstract: We report an application of the tri-dimensional pseudo-spectral time domain algorithm, that solves with accuracy the nonlinear Maxwell's equations, to predict second harmonic generation in lithium niobate ridge-type waveguides with high index contrast. Characteristics of the nonlinear process such as conversion efficiency as well as impact of the multimode character of the waveguide are investigated as a function of the waveguide geometry in uniformly and periodically poled medium.
\vlcurlybSrcurlybolc-Type Wavelength Filters Based on TE TM Mode Conversion Utilizing Periodically Poled Ti-Diffused Lithium Niobate Channel Waveguides  [PDF]
Hongsik Jung
International Journal of Optics , 2010, DOI: 10.1155/2010/626583
Abstract: We have demonstrated the ?olc-type wavelength filters in a 52?mm long periodically poled Ti-diffused lithium niobate channel waveguide which has a domain period of 16.6? m. At room temperature, the center wavelength and the full-width at half maximum of the filter were about 1272.49?nm and 0.23?nm, respectively. The nearest side-lobe is about 7?dB. New structure of optical add/drop multiplexer (OADM) utilizing ?olc-type TE TM mode converters was proposed for the first time. 1. Introduction The development of periodic poled Ti-diffused lithium niobate channel waveguides (Ti:PPLN) utilizing the electric-field poling techniques [1] allows good quality quasiphased-matched (QPM) waveguide devices which can be used in various optical application fields. Among the various periodically poled ferroelectric materials, a periodically poled lithium niobate (PPLN) is particularly attractive for various QPM devices due to its large nonlinear-optic coefficient and easy integration. The main application fields of QPM devices based on periodical poled titanium-diffused optical channel waveguides (Ti:PPLN) are all-optical wavelength conversion [2], optical pulse compression [3], all-optical switching [4], and all-optical logic gate because of their ultrafast nonlinear optical response and high-conversion efficiency. Actually, the electric-field poling of lithium niobate modulates not only the nonlinear optical coefficients but also the electro-optical coefficients due to periodically domain-inversion. These kinds of modulated structures can be used to compensate the phase mismatch between the ordinary and extraordinary wave in birefringent lithium niobate optical channel waveguides. Recently, the electric-field poling technique allows a new type of narrowband ?olc filter based on PPLN, which has thousands of birefringent plates [ ]. Although the ?olc filter was proposed more than 50 years ago, difficulties with the fabrication technology in making a large number of birefringent plate stacks have prevented the appearance of a practical narrowband ?olc-type wavelength filter [5]. Optical wavelength filtering and polarization mode conversion are key functions in an optical signal processing and communication systems. Optical wavelength filters have attracted much attention in applying to WDM systems due to their constant availability and reliability in the spectrum division and narrowing [6]. Among the diverse optical narrowband wavelength filters, birefringent ?olc-type wavelength filters can allow narrow and tunable spectral band. Section 2 of this paper reviews the
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