Quadratic Array Spatial Solitons: New Phenomena in Nonlinear and Soliton Science

斯蒂格曼空间孤子是一种无衍射光束，可以在克尔、可饱和克尔、光折变和二次非线性介质中自陷(对于参数混频是近相位匹配)。二次孤子是基于二阶非线性X(2)的，在最简单的情况下由一个基场和一个谐波场组成，它们随着y的传播相互自陷。以前的实验已经处理过在均匀介质中引导的孤子，无论是在块状介质中还是在波导中。最近，耶拿弗雷德里希·席勒大学的福尔克·莱德尔的团队预测，在几瓦的功率水平下，准相位匹配(QPM)LiNbO_3中的二次孤子也可以通过密集间隔的平行通道波导阵列来引导。这些阵列孤子通过基频场和谐波场之间以及阵列中相邻通道之间的强耦合来引导。他们的第一次观察、表征和他们之间的相互作用是这里提出的计划的主旨。这项研究有望在阵列结构中首次观测到新的孤子、位置相关的孤子相互作用和新的引导现象。这也应该导致可以推广到非线性离散系统领域的新知识，这是一个到目前为止还不容易通过实验获得的领域。PI是欧洲共同体(EC)计划的一个完整和正式的部分，该计划旨在研究准粉末LiNbO_3的新应用。欧洲的合作者包括福尔克·莱德尔，以及沃尔夫冈·索勒，他的组织(联合国。Paderborn)制作了准相位匹配LiNbO_3光波导，其相位匹配在8厘米以上。在这种用于20微米宽阵列空间孤子的样本中，通常需要1厘米用于孤子控制操作或碰撞。因此，这些波导第一次提供了激发此类孤子和研究多个顺序孤子相互作用的前景。此外，这些样品允许在瓦特峰值功率电平下激发孤子，比以前的情况减少了数量级。PI与耶拿和帕德伯恩小组合作，提议在准PM LiNbO_3平板光波导中产生这种阵列空间孤子，研究它们的性质，包括碰撞和电光和全光转向控制。PI的欧洲合作伙伴已经得到了ROSA的资助，ROSA是一项欧共体计划，不幸的是，它不允许为美国部分提供资金。在这里，PI要求为该计划的组成部分提供资金。尽管该计划将侧重于基础科学，但也将评估其应用的潜力。阵列引入的额外自由度导致了各种新的稳定孤子模，其中许多在齐次二次介质中没有类似的模式，也有一些在任何已知的非线性系统中都不存在。它们的性质还处于早期的理论阶段，将在1550 nm波长下进行实验研究。初步计算已经揭示了丰富的相互作用谱，包括与位置相关的结果，它们将进行实验研究。此外，还将研究与增益相关的孤子现象(已经在帕德伯恩的掺铒QPM LiNbO_3中演示)，包括聚焦、偏转等。此外，还将研究通过改变功率、通道间隔或折射率来扫描阵列中的孤子。

0098647StegemanSpatial solitons are non-diffracting beams which can be self-trapped in Kerr, saturable Kerr, photorefractive and quadratically nonlinear media (near phase-matching for parametric mixing). Quadratic solitons are based on the second order nonlinearity X (2) and in the simplest case consist of a fundamental and a harmonic field which are mutually self-trapped as the y propagate. Previous experiments have dealt with solitons guided in homogeneous media, either in bulk or in waveguides. Recently Falk Lederer's group at Frederich Schiller University in Jena predicted that quadratic solitons can also be guided by arrays of closely spaced, parallel channel waveguides in Quasi-Phase-Matched (QPM) LiNbO3 at power levels of a few watts. These array solitons are guided by virtue of strongcoupling both between fundamental and harmonic fields, and between adjacent channels in the array. Their first observation, characterization and interactions between them are the thrust of the program proposed here. This research is expected to lead to the first bservations of novel solitons, position dependent soliton interactions and new guiding phenomena in array structures. This should also lead to new knowledge that can be generalized to the field of nonlinear discrete systems, an area not readily accessible by experiment to date.The PI is an integral and formal part of a European Community (EC) program to study novel applications of QPM LiNbO3. The European collaborators include Falk Lederer, as well as Wolfgang Sohler whose group (Un. Paderborn) has fabricated QPM LiNbO3 waveguides, phase-matched over 8 cms. In such samples for 20 um wide array spatial solitons, typically 1 cm is required for a soliton control operation or collision. Thus for the first time these waveguides offer the prospect of exciting such solitons and investigating multiple sequential soliton interactions. Furthermore, these samples allow soliton excitation at watt peak power levels, a reduction of orders of magnitude over previous cases.In collaboration with the Jena and Paderborn groups, the PI proposes to generate such array spatial solitons in QPM LiNbO3 slab waveguides, investigate their properties, including collisions and electro-optic and all-optical steering control. The PI's European partners are already funded by ROSA, an EC program which unfortunately does not allow funding of the US part. Here the PI requests funding for the component of the program.Although this program will be focused on basic science, the potential for applications will also be assessed. The extra degrees of freedom introduced by the array lead to a large variety of new stable soliton modes, many without analogs in homogenous quadratic media, and some which do not exist in any currently known nonlinear system. Their properties are in their early theoretical stages and will be investigated experimentally at 1550 nm wavelengths. Preliminary calculations have revealed a rich spectrum of interactions, including position-dependent outcomes, and they will be investigated experimentally. Soliton phenomena associated with gain (already demonstrated in erbium implanted QPM LiNbO3 at Paderborn) will also be investigated including focusing, deflection etc. Furthermore, scanning of the soliton across the array by changing its power, the channel separation, or the refractive index electro-optically will be studied.